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Reactions of substituted bibenzyls and [alpha]-hydroxybibenzyls with supercritical water under coal liquifaction conditions

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Reactions of substituted bibenzyls and [alpha]-hydroxybibenzyls with supercritical water under coal liquifaction conditions
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Horiuchi, Akika Kusuoka
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xiii, 101 leaves : illustrations ; 28 cm

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Coal liquefaction ( lcsh )
Water -- Experiments ( lcsh )
Gas chromatography ( lcsh )
Mass spectrometry ( lcsh )
Coal liquefaction ( fast )
Gas chromatography ( fast )
Mass spectrometry ( fast )
Water -- Experiments ( fast )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

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Bibliography:
Includes bibliographical references (leaves 64-67).
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Submitted in partial fulfillment of the requirements for the degree, Master of Science, Department of Chemistry
Statement of Responsibility:
by Akiko Kusuoka Horiuchi.

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|University of Colorado Denver
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REACTIONS OF SUBSTITUTED BIBENZYLS AND
a'-HYDROXYBIBENZYLS WITH SUPERCRITICAL WATER UNDER
COAL LIQUIFACTION CONDITIONS
by
Akiko Kusuoka Horiuchi
B.A., International Christian University, 1969
A thesis submitted to the
Faculty of the Graduate School of the
University of Colorado in partial fulfillment
of the requirements for the degree of
Master of Science
1988


This thesis for the Master of Science degree by
Akiko Kusuoka Horiuchi
has been approved for the
Department of
Chemistry
by
Michael A. Mikita
Date


iii
Horiuchi, Akiko (M.S., Chemistry)
Reactions of Substituted Bibenzyls and a'-
Hydoxybibenzyls with Supercritical Water under
Liquifaction Conditions
Thesis directed by Assistant Professor Michael A. Mikita
Supercritical fluids have attracted special
interest due to their unique physical properties which
do not exist under common laboratory conditions.
Recently, supercritical water has been studied as a coal
liquifaction medium due to the relatively high coal
conversions exhibited in supercritical water and its
economic advantages. The object of this thesis was to
examine the role of water under coal liquifaction condi-
tions using substituted bibenzyls as the coal models.
To accomplish this goal, series of substituted
bibenzyls and a '-hydroxybibenzyls were synthesized via
Wittig reaction with subsequent hydrogenation. The
substituents synthesized were p-NI^, p-t-Bu, p-CH^, H,
m-CFg, and p-CH^OgC.
Both sets of compounds were reacted in a multi-
reactor system containing water under 4290 psi (0.30
kbar) at 4O0C for 3 hours corresponding to a super-
critical water density of 0.095 g/mL. In many instances
deuterium oxide was substituted for water. The


iv
dichloromethane soluble extracts from these reactions
were analyzed via gas chromatography-mass spectrometry.
Thermolysis pathways dominated the observed
products from the substituted bibenzyls. Both the ther-
molysis products and recovered starting materials were
observed to undergo deuterium exchange. The observation
of exchange implies previously unknown reaction pathways
water and bibenzyls under liquifaction conditions. The
mechanisms for these reactions were not rigorously
established, although electon donating substituents
favored substitution suggesting an ionic pathway. In the
case of p-carboxylic acid methyl ester bibenzyl,
demethylation and decarboxylation predominated with a
deuterium substitution pattern suggestive of an ionic
pathway.
Comparison of the product distributions in
and D20 for the a'-hydroxy substituted bibenzyls sug-
gests a primary isotope effect. This is an intriguing
observation considering that the thermolysis pathway
predominated.
The a'-hydroxybibenzyls exhibited more extensive
deuterium exchange than the simple bibenzyls, presumably
due to the enhanced H(D)-atom transfer ability of the
phenolic-H(D). The tautomerization pathway contributed


V
significantly to the product distribution with the a'-
hydroxybibenzyls. They also exhibited a primary isotope
effect suggesting that the tautomerization is rate
limiting.
2-Ethyl-4-substituted biphenyl ethers were also
observed in some cases, presumably through the rear-
rangement of certain substitued a'-hydroxybibenzyls.
Cyclization of p-NH2, p-CH^ and H a'-hydroxy
substituted bibenzyls to dibenzodihydrooxepane was also
observed.


Like all other arts, the Science of
Deduction and Analysis is one which can only
be acquired by long and patient study, nor
is life long enough to allow any mortal to
attain the highest possible perfection in it.
Sherlock Holmes, in "A Study in Scarlet"


To Katsura, Shu, Hokuto, and Tadashi.


ACKNOWLEDGEMENTS
I would like to express my greatful thanks to my
mentor Dr. Michael A. Mikita, for his instructions,
encouragements, and ever lasting zest for chemistry. To
Seifu Tadesse, Joel Boymel, Bonnie O'Connell, Roger
Simon, for teaching around the lab and keeping the
spirits up. To Dr. Robert Meglen and Dr. Larry Anderson
for careful reading of the draft and helpful sugges-
tions. To Tadashi without whom my entire research would
have being impossible.
I also like to express my gratitude to Prof.
Paul Fenessey and Mr. Alan Quick, of Univ. of Colorado
Health Science Center for MS analysis. To Dr. Bradley
Brockrath of US Dept, of Energy, Pittburgh Energy Tech-
nology Center, for encouragement and support, and to Mr.
Henry Davis for running the multireactor system. To Oak
Ridge Associated Universities for their financial assis-
tance in travel to Pittburgh by MAM. Finally, financial
support by US Dept, of Energy (DE-FG22-85PC815M) is
also greatly acknowledged.


CONTENTS
CHAPTER
I. INTRODUCTION................................... 1
1- 1 Object of the Study.................... 10
II. SYNTHESIS OF SUBSTITUTED BIBENZYLS............ 12
2- 1 Selection of Wittig Reagent............ 19
2-2 Protection of Hydroxy Group............ 20
2-2-1 Acetyl ether........................... 21
2-2-2 2-Tetrahydropyranyl ether............ 21
2-2-3 Benzyl ether........................... 22
2-3 Attempts to Synthesize
p-Bromobibenzyl......................... 22
2-4 Attempts to Synthesize
p-Nitrobibenzyl......................... 23
2-4-1 Reduction of p-nitrostilbene via
hydroboration......................... 23
2-4-2 Reduction of p-nitrostilbene via
diamide............................... 23
2-4-3 Hydrogenation of p-nitrostilbene
using rhodium as a catalyst........... 26
2-4-4 Oxidation of p-aminobibenzyl with
peroxytrifluoroacetic acid............ 26
2-4-5 Grignard reaction with copper
iodide catalyst....................... 27


X
III. RESULTS AND DISCUSSION........................ 28
3-1 Substituted Bibenzyls where R = H....... 32
3"2 Substituted Bibenzyls where R = OH...... 42
3~3 Future Plans............................. 49
3- 4 Conclusions............................ 49
IV. EXPERIMENTAL.................................. 52
4- 1 Synthesis.............................. 53
4-1-1 o-Bromo-p-toluic acid methyl ester.... 53
4-1-2 Salicylaldehyde benzyl ether........... 53
4-1-3 Salicylaldehyde acetyl ether........... 54
4-1-4 Salicylaldehyde tetrahydropyranyl
ether................................. 54
4-1-5 Pyridinium-p-toluenesulfonate.......... 55
4-1-6 Diethyl-p-methylbenzylphosphate........ 55
4-1-7 4-Methylstilbene....................... 56
4-1-8 4-Methylbibenzyl....................... 56
4-1-9 p-Bromobibenzyl........................ 57
4-1-10 p-Nitrobibenzyl....................... 57
A) By hydroboration reduction........ 57
B) By diimide reduction.............. 58
C) By hydrogenation with rhodium
catalyst.......................... 58
D) By oxidation with peroxide........ 59
E) By cuperous iodide coupling....... 59


xi
4-2 Reactions............................... 60
REFERENCES........................................... 64
APPENDIX............................................. 68


xii
TABLES
TABLE
1. Product Analysis of Thermolysis of
Bibenzyl by Various Researchers............... 9
2. Compounds used in the Reaction.............. 15
3. Preparation of Phosphonates................ 16
Preparation of Substituted Stilbenes....... 17
5. Preparation of Substituted Bibenzyls....... 18
6. Reaction of p-Nitrostilbene with Borane
Complex................................... 24
7. Reaction of p-Nitrostiblene with p-Toluene-
sulfonhydrazide.............................. 25
8. Hammett Reaction..................................... 31
9. Product Distributions of Major Products.... 34
10. Summaries of the Reactions................... 63


xiii
FIGURES
FIGURE
1. Ionization constant of water in
high-temperature fluids of various
densities................................... 3
2a. Hydrocarbon solubility (w$) in water........ 3
2b. Inorganic solubility (w$) in water.......... 3


CHAPTER I
INTRODUCTION
The ability of supercritical fluids (SCF) to
dissolve inorganic salts was first reported by Hannay
and Hogan at a meeting of the Royal Society of London in
1879.^ It was only during this past decade, however,
that the principles and practice of supercritical fluids
have experienced rapid advances. Supercritical fluids
have been applied to areas such as polymer and monomer
processing, natural product and pharmaceutical process-
ing, treatment of waste streams, and coal liquifaction.
Motivation for the development of supercritical fluid
technology is a result of the high costs for energy-
intensive separation techniques such as distillation.
Increased environmental awareness has also intensified
the search for non-toxic fluids to refrain traditional
industrial solvents, such as chlorinated hydrocarbons.
Increased demand for process techniques which tradi-
2
tional methods cannot meet and increased interest in
reactions under high temperature and/or pressure from a
pure chemistry point of view have together hastened
research with SCF.


2
The possible use of supercritical fluids in coal
liquifaction has recently attracted significant inter-
est. The typical solvent for coal liquifaction is an
organic solvent which can act as hydrogen donor, such as
tetralin. These donor solvents are commonly hydrogena-
tion products of coal liquifaction and thus refered to
as process derived solvents. The disadvantages with the
use of these solvents are high cost of their separation
from other products, and the necessity of subsequent
hydrogenation to make more efficient hydrogen donating
species. Some donor solvents also become fixed.in the
insoluble residue following liquifaction. Among common
solvents, water has attracted special interest because
of its low cost and relatively high coal conversion
3
rate.
Water has a critical temperature of 647.2K and
critical pressure of 217.7 atm. Above this critical
temperature, a liquid phase does not exist regardless of
the pressure. Consequently, supercritical water can be
more liquid-like or more gas-like depending on density.
Thus water above its critical temperature is most com-
monly referred to as a fluid. The ionization constants
of water in high temperature fluids of various densities
i)
is expressed in Fig. 1. For example, when density is
doubled at 400C the ionization constant increases by


c
to
4->
to
c
o
u
c
o
N
C
o
o>
o
3
Fig. 1. Ionization constant of water in high-temperature
fluids of various densities. The solid line is the
experimentally determined curve for liquid water under
its own vapor pressure. The estimated extrapolation of
the curve to the critical point is shown as a dashed
line. The other dashed lines shown calculated values
of the constant for single-phase fluid water under
sufficient pressure to maintain the indicated densities.
Fig. 2a. Hydrocarbon solubility Fig. 2b. Inorganic solubility
(wt %) in water (wt %) in water


about three powers of ten. Temperature and pressure
dependence of dielectric constant allow convenient
if
control of solvent properties over a large range. The
ionization constant of liquid water increases with
temperature, then drops rapidly just prior to the criti-
cal temperature. As the result, the solubility of
hydrocarbons in water increases dramatically as it
lj
reaches supercritical temperature(Fig. 2a, Fig. 2b).
Wender, et al.,(1984) have shown that when coal
is treated with supercritcal water alone, the amount of
THF extractable products depends upon the water density.
5
Barton (1983) has indicated that, in coal liquifac-
tion, water is a good extraction solvent as well as good
transportation medium.^ Stenberg and co-workers (198^)
studied supercritical water in presence of hydrogen
sulfide. Under their conditions, water acted only as
4
slurry liquid and did not participate in reactions.
In addition to the physical roles, water may
participate as a reactant. In combination with carbon
monoxide and hydroxide as catalyst, Ross and co-workers
found that water first reacts with carbon monoxide to
form formate which in turn reacts as a reducing reagent.
7 8
In this case, water is a hydrogen source. In contrast
to the carbon monoxide water system, in the hydrogen
sulfide water system studied by Stenberg, hydrogen


5
sulfide acted as hydrogen donor while water did not
react. In the thermolytic reaction of bibenzyl ether in
water, Paulaitis, et al.,(1983) have shown that bibenzyl
ether decomposed at 400C by both pyrolytic and
hydrolytic pathways, later leading to the formation of
benzyl alcohol, indicating direct participation by
9
water.
Recent experiments in this laboratory did not
exhibit an isotope effect when coal was liquified with
H^O or D^O along with tetralin and hydrogen. These
results suggest that under the experimental conditions,
water was not a rate limiting reactant. Similar experi-
ments in the absence of molecular hydrogen suggest that
molecular hydrogen plays dominant role regardless of
mechanism.^ Our group also has shown that when 4-benzyl
phenol was reacted with D20, recovered 4-benzyl phenol
contained at least two deuteriums. One explanation for
this observation may be electrophilic aromatic substitu-
11
tion of deuterium. The reaction of hydroquinone
monobenzylether in D,,0 resulted in the formation of
triply-deuterated catechol monobenzyl ether. While the
formation mechanism is still uncertain, this is another
indication of possible ionic pathways in the reaction of
supercritical water
12


6
Based upon this overview, it appears that super-
critical water sometimes plays a physical role, and
sometimes acts as an active participant. If the water is
a reactant, how does it react? If it behaves as a sol-
vent, does it assist reactions? These are some of the
many questions that still need to be answered regarding
coal liquifaction in a super critical water system.
The behavior of bibenzyl at high temperature has
been studied intensively by previous researchers. In
1979, Virk proposed a concerted mechanism in which the
intermediate (VI) takes hydrogen from dihydronaph-
thalene, followed by the cleavage of phenyl-phenyl
bond.1^

(VI )
This mechanism was immediately rejected by others. Stein
and Miller (1979) calculated the rate of reaction based
on the proposed mechanism and pointed out that the
-5 -1
observed k=10 sec was too slow for the calculated
value of k=10 sec Vernon (1 979) also indicated
that thermolysis of bibenzyl is not accelerated by the
presence of tetralin, a good hydrogen donor, indicating
15
no proton transfer.
Stein's and Vernon's results


7
supported a radical mechanism where radical cleavage of
ethane bond is proposed to be the rate determining
step.1^ The thermolysis radical cleavage mechanism of
bibenzyl is illustrated in Scheme 1.
Scheme 1
<0>- CH2CH2-@> 2 @-CH2
<0>- ch2 - ch2ch2-<§> > <§>-ch3 -chch2-<0>
<0>-ch ch2- @i-CH2 > - CH2 ch ch2-<>
&
---------> <@>-ch3+ <(o)-ch=ch-^o)
Extensive kinetic studies of pyrolysis of biben-
zyl in liquid phase at 300C-425C was done by Miller
20
and Stein (1981). The results where all in agreement
with a radical mechanism were the production of toluene
is first order in bibenzyl. Livingston, Zeldes and
Conradi (1979) observed 1,2-diphenylethyl radical by ESR


8
when bibenzyl was heated to 460C-560C. In the presence
of excess toluene, benzyl radical was observed at
21
560C. Ross and Blessing (1980) calculated half life-
times of bibenzyl at 400C and 335C, and found t1/2 to
22
be 2.0 hrs and 160 hrs respectively, based on log k
(sec 1) = 14.4-57/2.303RT.2^ They concluded that under
the standard reaction time of 30 min, thermal scission
can not play a significant role at these temperatures.
They also noted that coal conversion rate is not
directly related to the hydrogen donating ability of the
solvent, raising a question on the previously accepted
mechanism of simple thermal cleavage followed by capping
with proton.
Vernon (1980) studied hydrocracking of bibenzyl
at 450C, 30 min, in the presence of tetralin, tetralin
and molecular hydrogen, and molecular hydrogen alone.
Conversion rate increased when molecular hydrogen was
added to the tetralin. Also, conversion rate increased
as hydrogen pressure increased. This indicated direct
24
participation of molecular hydrogen.
The product analysis of the thermolysis of
bibenzyl at various temperatures, pressures and reaction
25
times, has been studied by Poutsma (1980). The
products of reactions, done by various researchers has


Table 1
Product Analysis of Thermolysis of Bibenzyl by Various Researchers
Product distribution (carbon equivalent X)" 2 3
Researchers Temp. Time p Conv. X Conditions 0CH3 0CH=CH0 02CHCH3 (0CH2CH0)2 (0CH2)2CH0 0CH2CH3 Phenanthrene 02CH2 a
Poutma ^ 901*0 13 mm 3d KP 1.7 combustion tuba 26.7 9.7 1.1 33.2 26.7 d d 0.6
401 20 hr 92 43.4 n* Indication of shaking 34.7 32.6 0.6 0.6 1.3 - 5.4 1.7 1.6
401 ISmtn liquid 1.4 30.0 10.6 11.2 44.6 3.3 - d d 0.3
401 20 hr liquid 95.0 59.0 7.3 3.4 2.2 1.0 - 2.4 19.3 1.0
Slalfiar 05 400 2hr liquid 71.2 2-1 mm pyrolysis 39.1 32,4 13.3 9.0 2.9 0.0 1.9 2.6 .
and Millar 400 30 mfn liquid 4.9-6.0 tuba, no shaking 3,0.7 12.4 12.4 33.2 5.4 1.5 2.9 2.0 -
Vamen ^ 490 30 min liquid 69,1 1,3am K 20 em tuba 43.7 41.6 - - 0.3 1.0 5.0 1 2.
load: 0.3-1.01
slov agitation
(molt*) x (carban naJ/14 <1) MlPoulama. Foal 1980,39, 3J3.
(2) LM.Vanwn. Fual WeO, 39,102.
(3) RIJillW, Sl.SUIn, J. Mu*. Own. 1991,93,390.
vO


10
been summarized in Table 1. While toluene and stilbene
were common products, the reactions of bibenzyl at high
temperatures is temperature sensitive as well as reac-
tion time sensitive.
Kakemura, et al., (1981) found that bibenzyl in
a carbon monoxide/water system with cobalt or molybdenum
as a catalyst, forms di- and tri- methylated benzenes
along with other minor products. Benzene and toluene
26
were the major products. In the presence of metal
catalysts the reactions seem to take completely dif-
ferent pathways.
1-1 Object of the Study
At first glance, water would appear to be
neither a good solvent nor a good reactant for the
commonly employed coal liquifaction model reactions. The
object of this thesis was to study the behavior of
supercritical water in the presence of a series of coal
models to examine whether water exhibits solvent
properties or reaction chemistry under liquifaction
conditions. Substituted bibenzyls were chosen as the
coal model compounds for two basic reasons. First,
bibenzyl is the most studied of the coal model compounds
at high temperatures, consequently it provides the most


11
established mechanistic pathways. Secondly, unlike
benzyl ethers which when radically cleaved will exhibit
some ionic character to the transition states, bibenzyls
are not expected to exhibit significant ionic character.
Consequently, ambiguity between radical reactions and
ionic reactions will be minimized.


CHAPTER II
SYNTHESIS OF SUBSTITUTED BIBENZYLS
All the bibenzyls used in the reaction with
supercritical water were synthesized according to the
reactions illustrated in Scheme 2 to Phosphonates (la
- Ig) were synthesized from substituted benzyl halides
and triethylphosphite (Scheme 2). All substituted benzyl
halides were commercially available except a-bromo-p-
toluic acetate which was synthesized from the methyla-
27
tion of oi-bromo-p-toluic acid with diazomethane.
Scheme 2 Synthesis of Phosphonates
R,"CH2H@" X + (EtO)3P
^ Y
R1 = Br or Cl
> - X
0 ^ y
X Y
l N02 H
lb t-Bu H
le CH3 H
Id H H
l H CF3
If CH30C0 H
<9 Br H


13
The phosphonates were coupled with benzaldehyde
or protected aalicylaldehyde, via Wittig reaction to
form the stilbenes (Scheme 3).
Scheme 3 Synthesis of Stilbenes
CEt0)2f-CH2- X -^)-CH-CH -^>
X Y R2 X Y R2
II a N02 H H III N02 H 0CH2O
II b t-Bu H H nib t-Bu H 0CH2O
II c CH3 H H III c CH3 H 0CH2O
II d H H H III d H H 0CH2O
II e H CF3 H III e H CF3 0CH2O
II f CH30C0 H H iii r CH30C0 H 0CH2O
II 9 Br H H III 9 Br H 0CH2O
Salicylaldehyde was protected as the benzyl ether,
according to the reaction illustrated below.
H Mr0CH2
Finally, the stilbenes were hydrogenated to
obtain the bibenzyls (IVa IVf, Va Vf), (Scheme M).


1H
Sheme 4 Synthesis of Bibenzyls
R2 R3
X Y R3 X Y R3
IV a NH2 H H V a NH2 H OH
IV b t-Bu H H Vb t-Bu H OH
IV c CH3 H H V c CH3 H OH
IV d H H H Vd H H OH
IV e H CF3 H Ve H CF3 OH
IV f CH30C0 H H Vf CH30C0 H OH
All substituted groups were unaffected by hydrogenation,
except benzyloxy, bromo and nitro groups. Benzyloxy and
bromo groups were eliminated while the nitro group was
reduced to the amino group. The physical properties of
these substituted bibenzyls are complied in Table 2. The
synthetic results are summarized in Table 3 5. A more
detailed discussion of each of these synthetic steps
will now follow.


Table 2 Compounds Used in the Reaction
R X Y Compound m.pt. exp/lit 0 C m.wt. m/e [relative sensitivityl
H nh2 H IVe 42-44/480) 197 197125, M4], 1061100, M4]
H t-Bu H IVb 37-30/ 238 23BI25, M+], 1471100, M4-PhCH2 1
H CHT H IVc (2) 25-26/24-26 196 196[25, M + ], 1051100, M4-PhCH2 ]
H H H IVd (3) 40.5-49.5/52-52.5 102 182[49, M4], 91M00, M+-PhCH2 J
H H cf3 IVe liquid 250 250125, M4], 159118, M4-PhCH2 ], 91 [100, PhCH2J
H CH30C0 H IVf 28-29/ 240 240125, M4], 149120, M4-PhCH2 1. 91 [100, PhCH2l
OH nh2 H Ve 138-144/ 213 213[14, M4], 1061100, M4-H0PhCH2 ]
OH t-BU H Vb 50-59.5/ 254 254142, M4], 1471100, M4-H0PhCH2 ]
OH CH, H Vc 54-55/ 212 212142, M4], 1071100, M4-CH3PhCH2 ], 105[100,
OH H H Vd 79-80/05w 198 19B[27, M4], 1071100, M4-PhCHzr 2
OH H *3 Ve 43-44.5 / 266 266125, M4], 1091100, M4-CF3PhCH2 ]
OH CH3OCO H Vf 92-100/ 256 256114, M4], 1071100, M4-CH30C0PhCH2 1
(1) J.V.Braun, H.Deutsch, OXoscielskl, Ber. 1913, 46,1511.
(2) Rl-HinMan, KJ-.Mamm, J. Am.Chem.Soc. 1959, 81,3294.
(3) Merck Index
(4) P.Ruggli, A.Staub, Helv.Chim.Acla. 1937,20, 37.


Table 3
Preparation of Phosphonatea
X (EtO)3P
^ V
R X Y gm mmole gm mmole
Br N02 H 10.8 50 8.3 50
Br t-Bu H 6.81 50 8.3 50
Br CH3 H 10.0 58 9.6 56
Br H H 5.90 50 8.3 50
Cl H CF3 8.48 50 8.3 50
Br CH30C0 H 8.00 35 5.8 35
Br Br H 6.25 25 4.2 25
(Et0)2P-CH2- 0 ^ Y
prod, gm/mmole % yield appearance
1 a 190-192/3 10.4/43 86.0 1. yellow
1 b 150-158/3 7.37/26 86.5 colorless
1 c 107-122/3 12.2/50 86.5 colorless
1 d 83-85/3 9.42/.041 82.7 colorless
1 e 121-122/3 6.12/21 80.4 colorless
1 f 170-232/2.5 6.40/22 64.0 1. yellow
i g 160-162/5.5 5.10/16 65.0 1. yellow


Table 4
Preparation of Substituted Stilbenes
(EtO)2P 1 n > X Gt COH 2 X H@HCH =C1I V ^ R2
comp gm mmole R2 gm mmole reocl time prod gm/mmolE yield % yield m.pt.'c exp/lil appearance
la 5.00 20.7 H 2.20 20.7 3 hrs n> 2.54/12.8 61.6 149-150/156 y powder
lb 3.6B 22.5 H 2.39 22.5 3 lib 2.12/6.3 28.4 95.5-97 / w needle
Ic 3.62 1S.0 H 1.60 15.0 48 lie 2.08/10.7 71.5 117-118/110-2 y pUle
Id 3.42 15.0 H 1.60 15.0 48 lid 2.30/12.8 85.2 122-123/124 w pUle
If 3.10 10.4 H mi 10.4 8 He 1.79/7.2 69.4 58-59 / v needle
i r 1.72 6.0 H 0.64 6.0 3 ii r 0.45/1.9 31.0 150-151/ w pUle
1 fl 5.06 16.0 H 1.70 16.0 2 m 3.60/13.9 86.8 136-137/139 w needle
if 1.04 7.7 0CH2O 1.62 7.7 3 in > 1.58/4.78 62.5 102-103/101 y needle
lb 2.84 10.0 0CH2O 2.12 10.0 8 in b 1.51/4.42 44.0 68.5-69/ w pUle
Ic 3.24 13.4 0CH2O 2.84 13.4 8 III c 1.98/5.05 37.7 58-59/ v needle
Id 4.00 17.5 0CII2O 3.71 17.5 8 III d 2.60/9.09 51.9 65-66 / y plate
11 5.00 16.9 0CII2O 3.58 16.9 8 III f 4.39/12.4 73.3 y oil
i r 4.58 16.0 0CH2O 3.39 16.0 3 III r 1.00/2.9 18.1 y oil
1* 3.31 10.7 0CH2O 2.27 10.7 2 III g 1.85/5.07 47.4 66.S-67.0/ v powder


Table 5 Preparation of Substituted Bibenzyls
Reactants Solvent Pd React Product
comp gm mmole type ml gm time comp gm mmole yield
II a 2.70 12.0 EtOH/THF 100/100 0.20 2 hrs IV a 2.35 11.9 99.4 *
lib 1.83 7.61 EtOH 200 0.10 2 IV b 1.80 7.55 99.3
lie 1.87 9.52 EtOH 200 0.10 2 IV c 1.62 8.31 87.3
lid 1.50 8.30 EtOH 200 0.10 2 IV d 1.39 7.64 92.0
lie 2.41 9.71 EtOH 220 0.12 2 IV e 2.40 9.66 99.4
II f 0.45 1.88 EtOH/THF 180/20 0.10 2 IV f 0.44 1.83 97.5
II g 1.45 5.59 EtOH 200 0.10 2 IV d 0.95 5.20 93.0
Ilia 2.46 7.43 EtOH/THF : 200/50 0.30 4 Va 1.50 7.14 94.7
lllb 1.27 3.70 EtOH 200 0.20 2 Vb 0.97 3.82 103
III c 0.95 3.70 EtOH 200 0.20 2 Vc 0.64 3.02 94.9
Did 1.28 4.46 EtOH 200 0.30 2 Vd 0.97 4.91 110
III e 4.39 12.4 EtOH 200 0.50 2 Ve 3.60 13.5 109
III f 1.00 2.90 EtOH/THF 150/50 0.30 3 Vf 0.98 2.82 97.3


19
2-1 Selection of Wittig Reagent
Two types of Wittig reagents were considered.
Triphenylphosphite, which, after reaction with benzyl
halide followed by base, forms the phosphorus ylide that
reacts as the nucleophile. The other was triethylphos-
phite, which reacts with benzyl halide to form diethyl-
phosphonic benzyl ether followed by treatment with base,
generating phosphonate carbanion, another strong
nucleophilic specie.
After isolation of triphenylbenzylphosphonium
bromide and diethylphenylphosphonate, both compounds
28 29
were reacted with benzaldehyde. Both produced
stilbene but reaction with diethylphosphonate exhibited
fewer side products, as identified by TLC. There are
three other advantages to the use of
diethylphenylphosphonate. The first is the
nucleophilicity of the intermediates. Phosphonate car-
banions are known to be more nucleophilic than analogous
30
ylides. The second is the required reaction condi-
tions. In the reaction of phosphonium bromide, n-butyl
lithium, a pyrophoric and a highly moisture sensitive
liquid, is used as a base. Consequently, extreme care
must be taken in its handling, and the reaction must be
done under a dry, inert atmosphere. On the other hand,


20
the reaction with phosphonate requires only sodium
hydride as a base. The latter reaction requires simply
the use of a drying tube rather than the dry, inert
atmosphere. The third advantage is the physical form of
the synthetic intermediates. The phosphonates are
usually liquids, whereas the phosphonium bromides are
solids. Solids are often difficult to obtain from oil.
As a result, phosphonate was selected as Wittig reagent.
2-2 Protection of Hydroxy Group
In the syntheses of a '-hydroxybibenzyls,
salicylaldehyde was used as a synthetic precursor. In
these syntheses, the hydroxy group must be protected
prior to Wittig reaction. The requirements for the
selection of good hydroxyl protecting groups are: 1)
they must react quantitatively with the hydroxyl group,
2) they should not interfere with the main reaction, 3)
they must be eliminated easily to return the original
hydroxyl group


21
2-2-1 Acetyl ether
The acetyl group was first chosen as a protect-
ing group since it is one of the most common protecting
groups, with simple synthetic procedures, and can be
eliminated readily under mild conditions.
Salicylaldehyde acetate was synthesized, follow-
31
ing the standard method. Salicylaldehyde acetate was
reacted with diethylbenzylphosphonate. The IR spectrum
of the dark yellow oil thus obtained revealed hydrogen
bonded OH, indicating the loss of an acetyl group.
Consequently, this method was abandoned.
2-2-2 2-Tetrahydropyranyl (THP) ether
THP ether was selected next since, in our
laboratory, protection of salicylic acid was success-
fully accomplished by THP. Preparation of THP ether was
32
carried out following Miyashita's method, in which 33
33 34
pyridinium-p-toluenesulfonate (PTS) is used as a
catalyst. Most of the starting materials were still
unreacted after 4 hrs, 24 hrs, and 48 hrs. Consequently,
this method was also abandoned.


22
2-2-3 Benzyl ether
In a benzyl ether, the bulky phenyl group is
separated by one methylene group which would be expected
to reduce steric hinderance. Benzyl ether is particulary
desirable since it can be eliminated by hydrogenation,
simultaneous with the reduction of the double bond in
the stilbene.
The benzyl ester of salicylaldehyde was syn-
thesized in relatively good yield (60 %) by Miyano's
35
method. The subsequent Wittig reaction was also suc-
cessful. The benzyl group was quantitatively eliminated
during hydrogenation in the presence of excess palladium
catalyst. Thus all a'-hydroxybibenzyls were synthesized
using salicylaldehyde benzyl ester via a'-
benzoylstilbenes.
2-3 Attempts to Synthesize p-Bromobibenzyl
Since hydrogenation of p-bromostilbene (Ilg)
resulted in elimination of bromide, direct bromination
of bibenzyl with bromine and a catalytic amount of iron,
was attempted following Litz. Four experiments were
done varying reaction time temperature and ratio of the
starting materials. GC/MS analysis indicated seven major


23
products, including p-bromobibenzyl, p-bromostilbene
(Ilg) and dibromo compounds. Since the capillary column
GC retention times were very close to each other,
separation of the products was not attempted.
2-4 Attempts to Synthesize p-Nitrobibenzyl
Hydrogenation of p-nitrostilbene (Ila) resulted
in reduction of the nitro group to the amino group.
Several attempts were made to synthesize and separate p-
nitrobibenzyl using alternative methods.
2-4-1 Reduction of p-nitrostilbene via hydroboration
p-Nitrostilbene (Ila) was treated with borane-
pyridine and borane-THF complexes, varying solvent,
temperature, reaction time and ratio of the
reactants, 3 as shown in Table 6. Run B resulted in
the best p-nitrobibenzyl/(IIa) ratio (0.56). Separation
was not attempted.
2-4-2 Reduction of p-nitrostilbene with diamide
p-Nitrostilbene (Ila) was reacted with p-
toluenesulfonhydrazide, a diamide precursor, following
39
Dervey and Tamalen's method. Reaction conditions are


Table 6
24
Reaction of of p-Nitrostilbene with Borane Complexes
Run lla* B* A* Solvent Reaction Conditions NBB/lla**
H3B:Py 1 i i to make acidic TVf lla + B : reflux 2 hr/over night + A : to make solution aeldic NP
2 1 excess - heat to 60 C NP
3 1 3 Py lla + B : 2 hr at room temp followed by refulxing at 60* C NP
4 1 1/3 1 Mesitylene lla + B : 80 C, 30 min 0.032
+ A : reflux over night
S 1 1 1 Triglyme lla + B : 210 *C 30 min 0.36
+ A : 210*C 90min
6 1 1 excess Triylyme lla + B :210*C 30min 0.37
+ A : 210 *C 90 min
7 1 1 3 Triglyme lla : 130 *C + B :210*C 30 min, + A : detect.
8 1 1 1 Triglyme lla + B : 210 *C 1 hr 0.56
+ A : 210*C 30min
9 1 1/3 1 Triglyme lla + B : 210 *C 30 min NP
+ A : 210*C overnight
H3B:THF 10 1 1 1 TW lla + B : -2*C bring to r.t. NP
+ A : 60*C 1 hr
11 1 1/2 1 Triglyme lla + B : -2*C 1 hr, bring to r.t., + A : 210*C 30min NP
12 1 1 1 TW lla + B :-7*C bring to r.t. sit over night, + A : NR
Hi in mole ratios of lla : B : A
$ H-: ratios of peak areas obtained and identified by GC/MS, equiped with thermal
ionization detector.
B: borane-complexes, A: propionic acid NBB: p-nitrobibenzyl


25
Table 7
Reaction of p-Nitrostilbene with p-Toluenesulfonhydrazide
Run Hi II a tsh' its solvent react. conditions . no. of GC peaks Hi it; PNBB/11 a
i i 2.3 triglyme 170#C, lOmin 24 1.73
2 i 2.3 DME 135 C, 30 min 28 0.72
3 i 2.3 triglyme add KOH/5 min 4 0.21
70 C, 35 min 11 0.11
h< in mol* ratio.
H- ratio of peak areas obtained and identified by GC/MS equipped with thermal
ionization detector.
TSH : p-toluenesulfonhydrazidei PNBB : p-nitrobibenzyl


26
summarized in Table 7. The best p-nitrobibenzyl/(IIa)
ratio (1.72) was obtained in Run 1, however there were
large amounts of sidq products and the quantitative
separation was not attempted.
2-4-3 Hydrogenation of p-nitrostilbene using rhodium as
a catalyst
Since rhodium is known to be a selective
40
hydrogenation catalyst, hydrogenation of (Ila) was
attempted using rhodium on aluminum as a catalyst. The
products included p-nitrobibenzyl, (IVa) and starting
material. The ratio of p-nitrobibenzyl/(IVa) was 0.46.
Separation was not attempted.
2-4-4 Oxidation of p-aminobibenzyl with
peroxytrifluoroacetic acid
Peroxytrifluoroacetic acid is known to be a
suitable oxidation reagent for aromatic amines, p-
Aminobibenzyl (IVa) was oxidized with
peroxytrifluoroacetic acid, following Pagano and Emmons'
41
method. There were four products, including p-
nitrobibenzyl and (IVa). The ratio of p-
nitrobibenzyl/(IVa) was 1.12. Although this method
seemed to be promising, the use of 90 % hydrogenperoxide
to generate peroxytrifluoroacetic acid, discouraged us


27
from running the reaction on a preparative scale.
2-4-5 Grignard reaction with copper iodide catalyst
It is known that copper(I)-catalyzed reaction of
Grignard reagents and organo halides result in the
M2
cross-coupling reaction of different organic groups.
Benzyl magnesium chloride and p-nitrobenzyl bromide were
reacted in the presence of copper iodide, p-
Nitrobibenzyl was obtained along with bibenzyl and two
other side products. The ratio of p-
nitrobibenzyl/bibenzyl was 0.26. Although the yield of
p-nitrobibenzyl/bibenzyl was not appreciable, the
separation using preparatory TLC was attempted. Although
four distinctive Spots were clearly separated on the
small scale silica gel TLC plates with benzene as
developing solvent, preparatory silica gel TLC exhibited
twenty seven visual bands. Each major band was analyzed
by GC/MS with only one fraction containing the desired
product in insufficient yield.


CHAPTER III
RESULTS AND DISCUSSION
H
Based upon the conclusions of Stenberg, water
would be expected as a reactant only if the reaction of
the substituted bibenzyls are ionic. An ionic alterna-
tive exists to the radical thermolysis pathway if
quinone methides are produced from a'-hydroxy sub-
43
stituted bibenzyls. This is illustrated in Scheme 5.
Scheme 5
XH@>- ch2ch2-^o)
HO
radical
x-<§)-ch2 + ch2~^o)
HO
D20
x-<@>- CH2D + D0CH2-^O>
DO
no exchange


29
The quinone methides could subsequently react with water
to form hydroxy cresols, a species which would not be
expected from radical reactions.
The reaction of both sets of models with
deuterium oxide was expected to be most informative. The
incorporation of deuterium into products from the sub-
stituted bibenzyls would strongly suggest ionic reac-
tions. The homolitic bond strength of H-OH in water is
119 kcal/mole, significantly higher than C-H bond (98
kcal/mole) or C-C bond in bibenzyl (61.6
kcal/mole)(Appendix 1). Consequently, in radical reac-
tions water would not be expected to react sig-
nificantly. This was the crux of Stenberg's explanation
of his experimental observations with water and H2S.
If the reactions occur ionically, the effect of
substituents should be significant. With a radical
reaction pathway, the effect should be minimal. The
effect of substituents on a reaction involving ionic
intermediates can be most effectively studied by Hammett
41j
linear free-energy relationship. If the plot of log k
vs. Hammett Hammett p is negative, the rate determining step in-
volves the process in which electron donating sub-
stituents accelerate the reaction, either by stablizing
intermediate or facilitating the leaving group. If p is


30
positive, the rate limiting step is accelerated by
electron withdrawing groups. Deviation from a straight
line plot implies a change in overall reaction pathway
as the nature of substituent is varied, or a shift in
the rate limiting step within the overall reaction
pathway. Corresponding employed in our study are given in Table 8.
All reactions were performed in a multireactor
system at the US Department of Energy, Pittsburgh Energy
Technology Center. Reaction conditions of 400C for 3
hours at 4290 psi H20 were employed in all cases.
Due to the limited amount of reactor time avail-
able to us at the Pittsburgh Energy Technology Center,
only one sample was run in duplicate as a test of
reproduciblilty (A#1, C#5). Inspite of the carefully
controlled reaction conditions, the production of higher
molecular weight compounds were inconsistent. Low
molecular weight compounds were similar but
product/internal standard ratios, as measured by in-
tegrated area under the GC peaks, were inconsistent as
well. Consequently, only qualitative discussions of the
more interesting reaction pathways follows.
The number of deuteriums incorporated into the
products has been calculated by comparing M, M+1 M+2,
45
abundance ratios from the literature, with isotope


31
Table 8
Hammett 0" m CTp 0"ind CTP+ CTp"
nh2 0.16 -0.66 -0.12 -1.30 -0.15
t-Bu 0.10 -0.20 -0.07 -0.26 -0.13
ch3 0.07 -0.17 -0.04 -0.13
H 0 0 0 0 0
CH3OCO 0.37 0.45 0.34 0.46 0.64
EtOCO 0.37 0.45 0.21 0.46 0.64
cf3 0.43 0,54 0.41 0.61 0.65
nh3+ 0.86 0.60 0.61


32
intensities reported as normalized to the intensity of
M. The isotopic abundance ratios of reaction products
are normalized to the highest intensity signal in the
vicinity of the parent peak. When experimental M+1 value
exceeded more than twice the literature value, it was
assumed that some molecules had molecular weights which
were increased by one, that is one deuterium was incor-
porated into it. Experimental M+2 was then normalized to
experimental M+1 abundance ratios, and again compared
with the literature value. When the M+2 value thus
calculated exceeded more than twice the literature
value, it was assumed that some molecules had molecular
weight which were increased by two, and so on. There is
no statistical basis for choosing twice the literature
value as a criterion, but measured natural abundance
ratios of the same compounds produced from different
starting materials all fell within twice the literature
value. The GC/MS results for all reactions are sum-
marized in Appendix 2.
3-1 Substituted Bibenzyls where R = H
For the compounds where R= H, the reactions were
run only in D20.


33
Toluene and substituted toluenes were the major
low molecular weight products in all cases. Both com-
pounds were multiply deuterated (Appendix 2). The maxi-
mum number of deuteriums incorporated into these
products do not correlate with substituent effects
suggesting radical-like reactions. Stenberg (1980)
indicated that water is not reactive as a hydrogen atom
transfer agent under liquifaction conditions. His con-
clusion was based upon experimental evidence and the
i)
high homolitic bond energy of H-OH, as was discussed
earlier. Inspite of this thermodynamic handicap, the
incorporation of deuterium in our reaction products
clearly suggests reaction with water. Such incorporation
can be envisioned either radically or ionically, al-
though the lack of corresponding hydroxyl compounds is
puzzling. Hydroxy-substituted compounds may have been
left in the aqueous layer, or may have polymerized to
form high molecular weight compounds which were not
identified at this stage.
The most abundant components of the
dichloromethane extract were deuterated starting
materials. There was an observed trend to the maximum
possible number of deuterium incorporated into the
starting materials. That is, the more electrondonating


34
Table 9
Product Distributions of Major Products
X products "oh XhO>_CH2CH3
\R OH H OH H
nh2 h2o 0.22(1) 0.16
d2o ND ND ND ND
ch3 h2o 0.12 0.15
d2o ND ND ND ND
H h2o 0.009 0.08
d2o 0.062 5D ND 0.026 4D ND
m-CFj h2o ND 0.017
d2o ND ND ND ND
ch3o2c h2o ND ND
d2o ND ND ND ND
(1)The numbers are the ratios of pentanol/product, measured by the area under
the CC peaks. ND: not detected. number D: the number of possible deuteriums
incorporated.


35
Table 9 continued
X products <£>CH3 R XhQ>"CH3
\r OH H OH H
nh2 h2o 0.56 0.062
d2o ND 0.21 3D ND 0.12 6D
ch3 h2o 0.27 0.36
d2o trace 0.053 3D
H h2o 0.10 0.32
d2o 0.23 6D 0.13(2) 3D 0.15 3D 0.13(2) 3D
m-CFj h2o 0.014 0.10
d2o 0.069 6D 0.16 2D 0.053 3D 0.064 2D
CH3O2C h2o 0.13 0.083 (-C02H)
d2o 0.047 0.0876D 0.18 3D 0.0685D trace 4D 0.14 (-C02H)4D
(2) experimental value x 1 /2


36
Table 9 continued
X products starting materials rearranged compounds
\R OH H OH H
nh2 h2o 0.84 OB
d2o 1.44 5D ND ND
ch3 h2o 0.80 OB
d2o 1.85 6D OB ND
H h2o 1.01 OB
d2o 1.51 7D 2.39 3D OB ND
ITI-CF3 h2o 1.14 OB
d2o 1.34 5D 1.83 2D OB ND
ch3o2c h2o ND
d2o 0.021 (-C02H) 3D 0.13 id 1.35C-C02H1 4D ND ND
OB: observed. ND: not detected, number D: the number of possible deteriums
incorporated


37
Table 9 continued
X products cyclic compounds high m. wt. compounds
\R OH H OH H
nh2 h2o OB OB
d2o OB ND OB ND
ch3 h2o OB OB
d2o OB ND OB
H h2o OB ND
d2o OB OB ND trace
m-CF3 h2o ND OB
d2o ND ND OB OB
ch3o2c h2o ND OB
d2o ND ND OB ND
OB: observed. ND: not detected.


38
the substituents, the more deuterium that was incor-
porated. Table 9 summarizes the major products. This
would suggest that the electron donating group en-
courages and stablizes the intermediates of the exchange
process.
Deuterium exchange may be envisioned by either
radical or ionic pathways as illustrated in Scheme 6.
Scheme 6
XGy-CH2CH2"> X--CT-CB2Hg> + D@ X--CH-CH2H@> + OD
D' OD D
If the reactions are radical, this would contradict
Stenberg's conclusions and appear thermodynamically


39
unfavorable. If ionic reactions are taking place, either
aliphatic or aromatic substitutions are possible. Route
B would be stablized by electron donating groups, but
alcohol products would be expected and these have not
been observed. Route C forms carbanion intermediates,
hence electron withdrawing groups would be expected to
stablize the intermediates. The electrophilic aromatic
substitutions illustrated via route A agrees with the
observed substituent effects, since electron donating
groups would be expected to stablize the intermediate
arenium ions. The deuterated products identified from
these reactions are illustrated in Appendix 2.
The formation of stilbenes from bibenzyl (IVd),
and m-trifluoromethyl bibenzyl (IVe), are consistant
with the radical mechanisms presented in Scheme 1.
Phenanthrene, which was also observed, is also a pos-
sible product from radical reactions (Scheme 7).


40
Scheme 7

i
H
H H
jr
R
The most intriguing reaction in this series was
the reaction of the carboxylic acid methyl ester sub-
stituted bibenzyl.(IVf). The most abundant
dichloromethane soluble specie was the demethylated
carboxylic acid (IVg). The demethylation process is
probably ionic, where water is acting as nucleophile
(Scheme 8).


Scheme 8

H--CH@)-CH2CH2- + CH30 H
0
( IVg )
(IVg) was also observed to decarboxylate to produce
bibenzyl (IVd) as one of the major products. The decar-
boxylation process can be envisioned either ionically,
or radically (Scheme 9 and 10).
Scheme 9
1
d-Q>-ch2ch2-0 co2


Scheme 10
DhQ-CH2CH2hQ
<0-ch2ch20 -
co2
The maximum number of deuterium incorporated into biben-
zyl produced from (IVf) was four, which was one more
than the number of deuterium incorporated into the
unreacted bibenzyl when bibenzyl was the starting com-
pound. This suggests the substitution of a deuterium for
the carboxylic moiety on the aromatic ring.
3-2 Substituted Bibenzyls where R = OH
For the compounds where R = OH, the reactions
were run in both 1^0, and There are two basic
comparisons. One is the comparison between the products
from the reaction in DgO when R = H (bibenzyls) and R =
OH (o-hydroxybibenzyls). Although strict quantitative


discussions are not possible due to the poor
reproducibility, simple comparisons were attempted.
The other comparison is product distribution
between reactions in the presence of H^O and D^O. The
products formed in each were similar. Generally, the
reactions proceeded more in H^O than D^O; unreacted
starting materials were less, and the. amount of reaction
products were greater in H^O. These results suggest the
presence of a primary isotope effect.
Every compound recovered from each reaction with
contained deuterium. The acidic hydrogen of the
phenol was expected to be readily exchanged with
deuterium from D^O. Since phenolic hydrogens are well
46
known hydrogen transfer agents in radical reactions,
the observed distribution of deuterium through out the
products was not surprising.
The major low molecular weight products observed
from o-hydroxy bibenzyls are: hydroxy toluene, sub-
stituted toluenes, phenol and substituted ethyl ben-
zenes. Hydroxy toluene and substituted toluenes are
possible products of the bibenzyl thermolysis reaction.
There was no clear indication of a substituent effect.
Generally, the amount of products produced in H20 were
greater than in D20.


44
On comparing the thermolysis products between R
= H, and R = OH, namely toluene and substituted toluenes
from run A with o-hydroxy toluene and substituted
toluenes from run C, there were no obvious trends in the
number of deuteriums incorporated into the products.
There were also no significant differences in the amount
of products formed. These results demonstrate the
dominance of radical thermolysis pathways even in the
presence of supercritical water.
Phenol and substituted ethyl benzenes are also
possible products resulting from the cleavage of aryl-
aliphatic bond. Neither compound was observed in the
reaction, where R = H. The phenolic group could
facilitate this cleavage, either ionically or radically
as shown in Scheme 11. Alcohols, the expected products
from ionic reactions were not identified. The radical
fragments from the alternative homolitic cleavage may or
may not react with D20 in order to incorporate
deuterium. Unlike R = H, where D20 is the only possible
deuterium source, the phenolic hydrogen will readily
exchange with deuterium oxide resulting in a labile
source of deuterium atoms. Upon comparing the amount of
these compounds formed from the reactions with H20 and
D20, the reactions with H20 produced a larger amount of
compounds. This would be expected if the formation of


45
the keto tautomer was rate limiting. Within the reaction
in the presence of H^O, the abundance of these products
seemed to increase as electrondonating ability of sub-
stituents increased. The reason for this trend is not
obvious (Table 8, and Appendix 2-C).
Scheme 11
Comparison of the amount of unreacted starting
materials was consistant with previous discussions. More
starting materials were observed in U^O than in H20, and
more when R = H, than R = OH. More deuterium incorpora-
tion was observed with increasing electrondonating
ability, but the trend was less clear than for R = H.


46
o-Hydroxyethylbenzene was found only from the
reaction of p-amino-a '-hydroxybibenzyl. Since the
electrondonating ability of the amino group is larger
than that of a hydroxyl group, a reaction such as that
illustrated in Scheme 12 becomes feasible.
Scheme 12
H20H 6h2CH2-£> ^
HO
Rearranged starting reactants were observed in
the p-NHg, p-CH^, H, and m-CF^ substituted cases, where
R = OH. A proposed reaction pathway is illustrated in
Scheme 13.


47
Scheme 13
X


0
if-
Cyclization seems to have occurred in bo.th H^O
and DgO where the substituents were p-NH,,, p-CH^ and H
groups. No cyclization products have been identified
where substituents were elec'tronwithdrawing groups. Two
possible pathways for these products are illustrated in
Scheme 14.
The reaction of p-amino-a'-hydroxybibenzyl in
D20 varied significantly from all other reactions. The
amount of internal standard, pentanol, recovered was
very small and the major product observed had a presumed
parent ion of a mass of 394. The explanation for the
anomaly remains elusive.


Scheme 14
Alternative

H8

t/ 0
H

X
0


i9
3-3 Future Plans
The establishment of quantitative reliability is
our major priority. To this end, we recently purchased a
Parr 22 ml microreactor which in other experiments has
lead to highly reproducible results. Once quantitative
reliability has been established, the suggested trends
from this work can be confirmed. Particular focus will
be on confirming the effect of substituents on deuterium
exchange. Other ambiguous reaction pathways will also be
tested through the use of radical scavengers such as
cresol or tetralin. Alternative Lewis acid catalysts may
also be added in an attempt to enhance ionic reactions.
3-1J Conclusions
The object of this thesis was to study the role
of water under coal liquifaction conditions using sub-
stituted bibenzyls and a'-hydroxybibenzyls as coal
models.
The series of substituted bibenzyls and a '-
hydroxybibenzyls were synthesized via Wittig reaction
followed by hydrogenation. The substituents synthesized
for both bibenzyls and a'hydroxybibenzyls were p-NH2,
p-CH^, H, m-CF^ and p-CH^C^C.


50
The model compounds were reacted with H^O or D^O
under 4290 psi (0.30 kbar), at 400C for 3 hours.
Thermolysis pathways dominated the reaction of
substituted bibenzyls. The thermolysis products and
recovered starting materials were observed to undergo
deuterium exchange. The observation of exchange implies
that previously unknown reactions are taking place
between supercritical water and the substituted biben-
zyls. Mechanisms for these reactions were suggested. In
the case of p-CH^C^C, demethylation, decarboxylation and
deuterium substitution dominated. This suggests an ionic
pathway. Comparison of the product distribututions
between H,,0 and D20 for the substituted a'-
hydroxybibenzyls indicates a primary isotope effect,
although the thermolysis pathway again predominated. The
a'-hydroxybibenzyls exhibited more deuterium exchange
than with the simple bibenzyls. This may be due to the
enhanced hydrogen transfer ability of phenolic hydrogen
under radical reactions. The tautomerization pathways
contributed significantly to the product distributions.
They also exhibited a primary isotope effect which
suggests that tautomerization is rate limiting. 2-Ethyl-
4-substituted diphenyl ethers were observed and are
possibly produced through the rearrangement of certain
substituted a'-hydroxybibenzyls. Cyclization of p-NH^,


51
p-CH^, H, substituted a'-hydroxybibenzyls to
dibenzodihydrooxepane was also observed.


CHAPTER IV
EXPERIMENTAL
When anhydrous solvents were required, the
solvents were dried over 3~A molecular sieves prior to
use. All commercially available reagents were used
without further purification.
Melting points were measured on a Mel-Temp
electrothermal melting point apparatus manufactured by
Laboratory Devices. The thermometer used was un-
calibrated and the reported melting points were not
corrected for high altitude. GC/MS analysis were per-
formed on a Hewlett Packard model 5890A mass selective
detector. A typical temperature program consisted of
elevating the temperature from 80C to 250C at 8C/min,
with 1.6 min solvent delay. IR spectra were recorded on
Perkin-Elmer 71 OB infrared spectrophotometer.


53
4-1 Synthesis
4-1-1 a-Bromo-p-toluic acid methyl ester
In an Erlenmeyer flask, a-bromo-p-toluic acid
(10 g, 0.0465 mol) was dissolved in 20 mL THF. The flask
was placed in a dry ice/acetone bath. Ethereal
diazomethane generated from 13.93 g (0.0651 mol) p-
toluenesulfonylnitrosamide, was distilled into the
flask. After distillation was completed, the flask was
removed from the dry ice/acetone bath and allowed to
come to room temperature while stirring. The completion
of the reaction was detected by the disappearence of
yellow color and vigorous foaming. After rotary evapora-
tion of the solvent, a white solid was obtained (11.96
g, 112 %, mp 30-160C). M/e (relative ionization): 228
[18.6, M+], 197 [19.7, M+- CH^, 149 [100.0, M+-Br], 90
[78.0, 149 COgCHg],
4-1-2 Salicylaldehyde benzyl ether
Benzyl bromide (15 mL, 0.126 mol) and potassium
carbonate (18 g, 0.13 mol) were slowly added to a solu-
tion of benzaldehyde (12.9 mL, 0.12 mol) in 75 mL
acetone at room temperature. After refluxing for 3.5
hrs, the entire mixture was taken up in a large excess


54
of H20 at which point, a yellow oil separated. The oil
was extracted with ether and washed with a sodium car-
bonate solution. The solvent was evaporated and the oil
distilled at 174-185C, 3 torr, yielding a yellow oil,
17.2 g (67.5 %). M/e (relative ionization): 212 [10.5,
M+], 183 [21.0, M+- CHO], 121 [24.5, PhCHO], 91 [100,
PhCH2].
4-1-3 Salicylaldehyde acetyl ether
Acetic anhydride, 150 mL, and potassium car-
bonate, 150 g, was added to the solution of salicylal-
dehyde (100 g, 0.82 mol) in 500 mL ether. The mixture
was stirred at room temperature for 30 min, after which,
solids were filtered off. Following rotary-evaporation
of ether, the oil was taken up into water at which point
a white solid separated. Recrystallization from
petroleum ether gave 56 g (46 %) white needle, mp 36.5-
38C (38C).18
4-1-4 Salicylaldehyde tetrahydropyranyl ether
Dihydropyran (6.3 g, 0.075 mol) and pyridinium-
p-toluenesulfonate (1.26 g, 0.05 mol) were added to a
solution of salicylaldehyde (6.1 g, 0.05 mol) in 150 mL
dichloromethane. The solution was stirred at room tem-


55
perature for 4 hrs, 24 hrs, and 48 hrs. GC/MS of reac-
tion aliquots indicated that only the reactants were
present.
4-1-5 Pyridinium-p-toluenesulfonate (PPTS)
p-Toluenesulfonic acid monohydrate (28.5 g, 0.15
mol) was added to pyridine (69.5 mL, 0.74 mol) with
stirring at room temperature. After stirring for 20 min,
the excess pyridine was rotary-evaporated to produce a
white solid. Recrystallization from acetone gave, white
crystals, 37.7 g (73.7 ?), mp 116-118C (120oC).311
All bibenzyls were synthesized via phosphonates
and stilbenes, as exemplified below by the synthesis of
p-methy1-bibenzyl.
4-1-6 Diethyl-p-methylbenzylphosphate (Ic)
a-Bromo-p-xylene (10.0 g, 0.055 mol) was dripped
into triethylphosphite (9.6 g, 0.058 mol) with stirring
over a period of 25 min at room temperature. The solu-
tion was refluxed over night. Distillation at 107-122C,
3 torr, gave 12.2 g (86.5 %) of a clear colorless liq-
uid. M/e (relative ionization): 242 [12.2, M+], 213
[5.2, M+- Et], 105 [100, N^-tEtO^PO]. This material was


56
used without further purification.
4-1-7 4-Methyl-atilbene (lie)
Diethyl-p-methylbenzylphosphonate (Ic) (3.62 g,
0.015 mol) was dripped into the mixture of sodium
hydride (0.31 g, 0.015 mol) in 50 mL dry
dimethylethoxide with stirring at room temperature,
followed by slow addition of benzaldehyde (1.5 g, 0.015
mol). After refluxing for 2 days, the mixture was taken
up in a large excess of water, at which point, a crys-
taline solid was obtained. Recrystallization twice from
95 % ethanol gave 2.08 g (71.5 %) of light yellow
plates, mp 117118C.
4-1-8 4-Methyl-bibenzyl (IVc)
4-Methyl-stilbene (lie) (0.954 g, 3.18 mmol) was
dissolved in 200 mL absolute ethanol. Palladium on
carbon was added as catalyst. Following hydrogenation in
a Parr hydrogenator at room temperature for 2-4 hrs, at
30 psi, the catalyst was filtered and the solvent
evaporated to yield a tan solid (0.64 g, 3.02 mmol (94.9
%)), which was pure by GC/MS. M/e (relative ionization):
196 [25, M+], 105 [100, M+- PhCHg]. mp 25-26C
(24-26 C).1,7


57
4-1-9 p-Bromobibenzyl
Bromine (4.31 g, 0.024 mol) was added slowly to
the solution of stilbene (5 g, 0.027 mol) in 20 mL
acetic acid, containing 0.05 g iron filing. The mixture
was heated at 63C, for 4 hrs. The insoluble materials
were filtered, and the solution was neutralized with 10
% sodium hydroxide, followed by extraction with ether.
Rotary-evaporation of the ether gave a dark yellow oil
containing 2 different isomers of monobromostilbene,
stilbene and a small amount of dibromo substituted
compounds, as evidenced by GC/MS. The desired product
was not isolated.
4-1-10 p-Nitrobibenzyl
A) By hydroboration reduction. Borane-pyridine
complex (0.12 g, 1.3 mmol) was dripped into the solution
of p-nitrostilbene (0.3 g, 1.3 mmol) in 5 mL dry diglyme
at room temperature. The mixture was refluxed at 210C
for 30 min. After cooling to room temperature, propionic
acid (0.078 g, 1.3 mmol) was added. The mixture was
further refluxed for 30 min. The resulting mixture
contained p-nitrobibenzyl and p-nitrostilbene with a GC
peak area ratio of 0.56. Refluxing for an additional 60
min increased the amount of side products, resulting in


58
a decrease of p-nitrobibenzyl/p-nitrostilbene ratio to
0.36. The products were not isolated.
B) By diimide reduction. A solution of p-
toiuenesulfonyhydrazide (0.57 g, 3 mmol) in 3 mL trig-
lyme was slowly added to a solution of p-nitrostilbene
(0.3 g, 1.3 mmol) in 7 mL triglyme, at room temperature.
As the temperature raised slowly, the solution started
to foam. In 10 min, the temperature reached 170C at
which point, the foaming subsided. GC/MS of the mixture
indicated the presence of 24 compounds including p-
nitrobibenzyl. The GC peak ratio of p-nitrobibenzyl/p-
nitrostilbene was 1.73. Purification was not attempted.
C) By hydrogenation with rhodium catalyst, p-
Nitrostilbene was dissolved in 100 mL/50 mL,
ethanol/THF, to which rhodium on alumina (0.01 g) was
added as catalyst. After shaking at room temperature,
for 2 hrs. under 30 psi in a Parr hydrogenator, the
catalyst was filtered. As analyzed by GC/MS, the solu-
tion contained p-nitroblbenzyl, p-nitrostilbene, and two
other products. The GC peak area ratio of p-
nitrobibenzyl/p-nitrostilbene was 0.46. Purification was
not attempted.


59
D) By oxidation with peroxide. 90 % Hydrogen
peroxide (0.7^^ mL, 0.0279 mol) was added slowly to 12
mL dichloromethane at room temperature, without stir-
ring. The solution was then placed in an ice bath,
followed by slow addition of trifluoroacetic anhydride
(3.9 mL, 0.0279 mol) with stirring. The solution was
stirred for 30 min as it was brought to room temperature
at which point p-aminobibenzyl (1.1 g, 5.58 mmol) in 10
mL dichloromethane was slowly introduced by dropwise
addition. After refluxing for 1 hr, the cooled solution
was taken up in 20 mL water. The organic layer was
washed with water, 10 % sodium carbonate, and again with
water. After treatment with activated charcoal, and
drying with magnesium sulfate, the solvent was
evaporated. The dark brown oil thus obtained (0.3-h g)
contained p-nitrobibenzyl and p-aminobibenzyl with GC
peak area ratio of 1.21. Four other minor products were
also observed. Separation was not attempted.
E) By cuprous iodide coupling. Cuprous iodide
(1.63g, 8.5 mmol) and triethylphosphite (0.28 g, 1.71
mmol) were added to a solution of p-nitrobenzylbromide
(2.0 g, 7.66 mmol) in 20 mL THF. The mixture was cooled
to -29C with an o-xylene/liquid nitrogen bath. A THF
solution of benzyl magnesium bromide (11.5 mmol), syn-


60
thesized from benzyl bromide (1.52 g, 12 mmol) and
magnesium (0.32 g, 13.2 mmol), was added slowly. The
mixture was brought to room temperature while stirring
for 2 hrs, after which 20 mL of ether was added. The
mixture was washed.with sodium chloride solution. The
light yellow solution thus obtained contained four
compounds by GC/MS, including p-nitrobibenzyl, bibenzyl,
p-nitrobenzylbromide and one other minor side product.
The GC peak area ratio of p-nitrobibenzyl/bibenzyl was
0.26. Purification by preparatory silica gel TLC was
attempted. Out of 27 bands which as been separated, only
one band contained the desired product in insignificant
yield.
4-2 Reactions
A multireactor system at the US Department of
Energy, Pittsburgh Energy Technology Center was employed
for the reactions. The system consists of five in-
dividual microautoclaves, each of approximately 45 mL
46
capacity and attached to a single yoke. The entire
assembly was immersed rapidly into a preheated,
fluidized sand bath, allowing it to heat-up to reaction
temperature in 4-6 minutes. Immersion in a second
fluidized sand bath held at room temperature provided


61
rapid quenching. The autoclaves were agitated by a rapid
horizontal-shaking motion, assuring good mixing of
heterogeneous, multiphase mixtures. Individual ther-
mocouples allowed continuous temperature monitoring of
each microautoclave.
The reaction conditions were chosen so that 2.6
mmole of each compound was reacted in presence of 4.3 mL
H^O or D20, containing 2 mL pentanol/93.4 mL H20, or 2
mL/100 g D20, as internal standard. This resulted in the
mole ratio of the reactant to standard of 2 : 1. Pen-
tanol was selected as standard since its solubility in
water (16.6 g/100 mL at 20C) was just large enough to
ensure the desired concentration, yet would favor parti-
tion into dichloromethane upon work up. All reactions
were run at 400 C for 3 hrs.
The pressure at reaction temperature was not
measured directly in these experiments. Using van der
Waal's equation, the partial pressure of water was
estimated as 4290 psi. The density of supercritical
water was 0.095 g/mL.
After the reaction, the interior of the reactor
was washed several times with a total of 5 mL
dichloromethane. The dichloromethane, the aqueous mix-
ture thus obtained was shaken so that equilibrium of the
products between two layers was achieved. Each


62
dichloromethane layer was analyzed by GC/MS using two
different GC columns. Methyl silicone coated 25 m capil-
lary column was used for lower molecular weight com-
pounds under standard conditions, and 12 m, DV I capil-
lary column for higher molecular weight compounds, with
temperature elevation of 8C/min, from 80C to 300C.
Table 10 summarizes the reaction.


63
Table 10
Summaries of the Reactions
Run X R System
A 1 ch3o2c OH Vf D20
2 m-CFj OH Ve d2o
3 H OH Vd d2o
4 ch3 OH Vc d2o
5 nh3 OH Va d2o
B 1 ch3o2c OH Vf h2o
2 m-CF3 OH Ve h2o
3 H OH Vd h2o
4 ch3 OH Vc h2o
5 nh3 OH Va h2o
C 1 nh3 H IVa d2o
2 H H IVb d2o
3 ch3o2c H IVf d2o
4 m-CF3 H IVe d2o
5 CH302C OH Vf d2o


REFERENCES
1. a) J. B. Hannay, J. Hogarth, Proc. R. Soc. London,
29, 324 (187^) b) J. B. Hannay, J. Hogarth, Ibid.,
30, 178 (1880)
2. M. A. McHugh, V. J. Krukonis, "Super Critical Fluid
Extraction", ButterworJths (1986)
3. G. A. Wiltsee Jr., Quarterly Technical Progress Re-
port for the Period July 1983 Sept. 1983, Prepared
for the U. S. Department of Energy, Office of Fossil
Energy, Under Cooperative Agreement DE-FC01-
38FE60181,17
4. V. I. Stenberg, R. D. Hei, P. G. Sweeny, J. Nowock,
Am. Chem. Soc. Div. Fuel Chem. Preprints, 29(5), 63
(1984), and references cited there in.
5. G. V. Deshpande, G. D. Holder, A. A. Bishop, J.
Gopal, I. Wender, Fuel, 63, 956 (1984)
6. P. Barton, Ind. Eng. Chem., Process Des. Dev., 22
589 (1983)
7. D. S. Ross, J. E. Blessing, Q. C. Nguyen, G. P. Hum
Fuel, 63, 1206 (1984)
8. D. S. Ross, Q. C. Nguyen, G. P. Hum, Ibid.,63, 1211
(1984)
9. M. E. Paulaitis, M. T. Klein, A. B. Stilles, DOE
Quarterly Report, DE-FD22-82PC50799, July-Sept.
(1983)
10. B. D. Blaustsin, B. C. Bochrath, H. N. Davis, M.
A. Mikita, Am. Chem. Soc. Div. Fuel Chem. Preprint
30(20), 359 (1985)
11. M. A. Mikita, H. T. Fish, Ibid., 31(4), 56 (1986)
12. H. T. Fish, M. A. Mikita, Abstact Am. Chem. Soc.
193rd National Meeting, April 6, 1987, Denver
Colorado


65
13. P. S. Virk, Fuel, 58, 148 (1979)
14. R. A. Miller, S. E. Stein, Am. Che;m. Soc. Div. Fuel
Chem. Preprint, 24(2), 271 (1979)
15. L. W. Vernon, Ibid., 24(2), 143 (1979)
16. Y. Sato. Fuel, 58, 318 (1979)
17. D. C. Cronauer, W. L. Kehl, Ind. Eng. Chem. Fundam.,
17, 291 (1978)
18. B. M. Benjamin, Fuel, 57, 378 (1978)
19. D. D. Whitehurst, EPRI Report AF-480, 9-44 (1977)
20. R. E. Miller, S. C. Stein, J. Phys. Chem., 85, 580
(1981 )
21. R. Livingston, H. ZeldeS, M. S. Conradi, J. Am.
Chem. Soc., 101, 4312, (1979)
22. D. S. Ross, J. E. Blessing, in "Coal Liquifaotion
Fundamentals, ACS Symposium Series 139", D. D.
Whitehurst ed., 301, (1980)
23. S. W. Benson, H. O'Neal, "Kinetic Data on Gas Phase
Unimolecular Reactions", National Bureau of
Standards, NSRDS-NBS21 (1970)
24. L. M. Vernon, Fuel, 59, 102 (1980)
25.. M. L. Poutsma, Ibid., 59, 335 (1980)
26. Y. Kakemura, H. Itoh, K. Ouchi, Ibid., 80, 379 (1981)
27. Fieser and Fieser, Reagents for Organic Synthesis
vol.1, 191, John Wiley (1967)
28. G. Wittig, Organic Syntheses, vol 40, 66 (1960)
29. G. M. Koslapoff, "Organophosphorus Compounds"
Chapt. 7, John Wiley (1950)
30. F. A. Carey, R. J. Sunberg, "Advanced Organic
Chemistry, second ed., Part A", Plenum Press
(1984)


66
31. T. Makin, N. Nierenstein, J. Am. Chem. Soc. 53
239 (193D
32. N. Miyashita, A. Yoshikoshi, P. A. Grieco, J.
Org. Chem., 42, 3772 (1977)
33. J. H. Van Boom, Synthesis, 169 (1973)
34. C. B. Reese, R. Saffhill, J. E. Sulston, J. Am.
Chem. Soc., 89, 3366 (1967)
35. M. Miyano, et al., Nippon Nogei Kagaku Shi, 34(8)
683 (1960)
36. R. E. Litz, et. at., J. Org. Chem., 12, 617 (1947)
37. H. C. Brown, K. Murray, J. Am. Chem. Soc., 81, 4180
(1959)
38. Fieser and Fieser, Reagents for Organic Synthesis
vol. 8, 50 (1980)
39. G. E. Ham, W. P. Coker, J. Am. Chem. Soc., 29, 194
(1 964)
40. R. E. Dewey, E. E. van Tamalen, J. Am. Chem. Soc.
83, 3729 (1961)
41. G. E. Pagano, W. D. Enmons, Organic Syntheses, vol.
49, 47 (1969)
42. H. Alper, ed., "Transitionmetal Organometallics in
Organic Synthesis", vol. 1, 114, Academic Press
(1976)
43. H. U. Wagner, R. Gompper, in "The Chemistry of the
Quinoid compounds, Part 2", S. Patai, ed., John
Wiley, 1145 (1974)
44. P. Sykes, "A Guide Book to Mechanism in Organic
Chemistry, sixth ed.", 358, Longman (1986)
45. R. M. Silverstein, G. C. Bassler, T. C. Morrill
"Spectrometric Identifaication of Organic
Compounds, fourth ed.", John Wiley (1981)
46. Y. Kamiya, T. Yao, S., Oikawa, in "Coal Liquifaction
Fundamentals, ACS Symposium Series 139", D. D.
Whitehurst ed.,291, Am. Chem. Soc. (1980)


47. R. L. Hin Man, K. L. Mamm, J. Am. Chem. Soc.
81, 3294 (1959)
48. R. R. Anderson, B. C. Bockrath, Fuel, 63, 329
(1984)


68
Appendix 1
HOMOLYTIC BOND STRENGTH
H-OH 119.0 <1) kcal/mole
aromatic C-H 110.6 1 (2) 3 4
_ (2)
prim. C-H 97.9
sec. C-H 94.6 (2)
benzylic C-H 81.9 (2)
bibenzyl C-C 61.8 <2) (57) ^
(1) J.McMurry, "Organic Chemistry, 2nd ed.", Brooks and
Cole (1988)
(2) S.V.Benson, "Thermochemical Kinetics, 2nd ed.
Wiley, (1976)
(3) D.F.McMillan, D.M.Golden, Annu. Rev. Phys. Chem., 33
493(1982)
(4) D.S.Ross, J.E.Blessing, "Coal Liquifaction Fundamentals
ACS Symposium Seires 139", Am. Chem. Soc., 301
(1980)


69
Appendix 2
Analysis of the Dichloromethane Extractable
Compounds by GC/MS 1 2 3 4 5
X m. wt. (1) Compound identified no. of D formula incorporated
Mass spectrum data(2;) m/e [relative intensity]
Mass
Literature values(3)
R sample no. h2o retention time int. stand ^ comp Exp. values 1
sample no. d2o retention ti me int. stand comp Exp. values 2
(1) Suggested strtusture is drawn with [ ].
(2) Mass spectrum data of the raction in the presence of water.
(3) R.M.Silverstein, G.C.Bassler, T.C.Morrill, "Spectrometric Indentification
of Organic Compounds, 4th ed., John Wiley and Sons (1981)
(4) The ratio of integrated GC peak areas.
(5) Mass abundances are normalized to the highest peak at the vicinity of the
parent peak.


70
Appendix 2 A
CH3C- II 0 108 C>CH3 c7h80 oh
108[53,M+], 107[ 100, M+-H], 90[32, M+-H20], 77 [42,0- ]
107 108 109 110 111 112 113 114
100 77.3 0.43
OH B*1 h2o 5.60 100 87.7 10.4
0.128
A1 d2o 5.21 78.5 0.89 100 76.0 40.1 100 52.8 6D
0.047
C*5 d2o 5.02 3.2 25.4 77.5 100 84.1 42.0 12.7 100 30.0 6D
0.087


71
Appendix 2 A (continued)
CH3C- II 0 94 <0>_OH c6h6o

94 95 96 97 98 99
100 6.62 0.38
OH B*1 h2o ND
A*1 d2o ND
C*5 d2o 4.21 0.013 100 91.3 22.1 100 24.0 5D


72
Appendix 2 A (continued)
CH3C- II 0 136 hch£>ch3 CaHjo 0
136159, M+], 119[51, M+ OH], 91 [100, M+ C02H]
135 136 137 138 139 140 141
100 8.85 0.75
OH B1 h2o 6.3 100 10.6
A*1 d2o 84.0 100 87.3 4D
C5 d2o 29.5 71.4 100 81.8 50.2 18.1 100 35.7 5D


73
Appendix 2 A (continued)
CH3C- II 0 198 H -- CH2CH2 C14Hi40 H-0
198[23, M+], 107(100, M+ 0CH2]
198 199 200 201 202 203 204 205
100 15.4 1.30
OH B1 h2o 13.75 100 17.6
0.040
A*1 d2o 13.72 100 77.6 7D
0.054
C5 d2o 13.71 75.1 100 76.6 64.2 100 83.5 7D
0.022


74
Appendix 2 A (continued)
CH3C- II 0 226 H_(nH0>CH2CH2'O c15h14 2 other unidentified peaks

226 227 228 229
100 16.5 1.68
OH B1 h2o ND Y
A1 d2o ND Y
C*5 d2o 16.05 100 100 63.2 3D Y
0.021


75
A
P
P
e
n
d
i
x
2-B
nh2 92 <@>-Ch3 C7Hs 3D
H C*1 d2o 1.94 90 91 92 93 94 9 5 96
100 7.69 0.25
0.205 27.6 100 86.8 23.2 5.4 0.8 100 23.2 13.1
H 92 C7H8 <0>-CH3 3D
H C*2 d2o 1.94 90 91 92 93 94 9 5 96
100 7.69 0.25
0.264 22.7 90.7 100 42.5 10.4 1.4 100 23.0 3.3
CH30C n 0 92 C7H8 -ch3 3D
H C*3 d2o 1.94 90 91 92 93 94 9 5 96
100 7.69 0.25
0.180 5.9 33.7 100 94.2 38.6 10.2 1.8 100 26.0 4.6
ITI-CF3 92 <0>-CH3 C7H8 3D
H C*4 d2o 1.94 90 91 92 93 94 9 5 96
100 7.69 0.25
0.160 5.0 37.5 100 86.0 24.1 3.0 100 28.0 3.4


76
A
P
P
e
n
d
1
x
2-B
cont.
nh2 107 NH2 -<0> CH3 C7H80 5D
H C*1 d2o 5.34 107 108 109 110 111 112 113
100 7.73 0.46
0.121 3.4 15.4 61.8 100 61.8 30.7 7.7 100 49.6 12.0
H
H C*2 d2o


CH30C u 0 136 C0H0O2 H0Ch(o>-CH3 0 4D
H C*3 d2o 8.32 136 137 138 139 140
100 8.85 0.75
0.140 41.5 100 97.8 46.5 14.5 100 31.2
m-CF3 160 C0H7F3 ^0>-CH3 CF3 2D
H C*4 d2o 2.22 159 160 161 162 163
100 8.76 0.34
0.064 14.9 57.2 100 46.5 7.9 100 11.2


77
nh2 197 NH2 ->-CH2CH2 -(o) C14 H15 N 5D
H C*] d2o 14.48 197 198 199 200 201 202 203 204
100 15.8 1.16
1.440 6.3 11.4 64.3 100 91.7 45.8 12.4 2.9 100 27.0 6.3
H 182 Hh(o)-CH2CH2 - c14h14 30
H C*2 d2o 11.18 179 180 181 182 183 184 185 186
100 15.4 1.10
2.387 60.4 100 100 40.7 7.4 100 18.2
CH30C ii 0 240 CH30C -(O)- CH 2 CH 2 - 0 Ci6H1602 1D
H C*3 d2o 11.15 240 241 242 243
100 17.6 1.86
0.245 100 41.0 12.6 5.4 100 30.7 13.2
m-CFj 250 <^0^~ CH 2 CH 2 -(O) Cl5H13F3 CF3 2D
H C*4 d2o 11.06 248 249 250 251 252 253 254
100 16.4 1.26
1.832 100 66.2 44.4 11.1 1.8 100 25.0 4.1


78
A
P
P
e
n
d
1
x
2-B
cont.
nh2
H C*\ d2o


H
H C*2 d2o


CH30C u 0 182 c14h14 H_^0) dH2CH2 -(o) 4D
H C*3 d2o 1 1.15 180 161 182 183 164 185 186 187
100 15.4 1.10
0.245 8.5 5.6 13.2 85.0 100 50.5 19.0 5.5 100 37.6 10.1
m-CFj
H C*4 d2o




79
A
P
P
e
n
d
i
x
2-B
cont.
nh2
H C*1 d2o


H
H C*2 d2o


CH30C ii 0 226 H OC ~^0) CH 2 CH 2 ~^0) 0 C15H14O2 4D
H C*3 d2o 16.18 226 227 228 229 230 231
100 16.5 1.68
1.352 48.3 100 93.2 52.8 23.6 6.5 100 27.5
ITI-CF3
H C*4 d2o




80
A
P
P
e
n
d
i
x
2-B
cont.
nh2
H C*1 d2o


H 180 Ci4H12 ID
H C*2 d2o 13.14 176 177 178 179 180 181 182
100 15.3 1.09
0.086 11.8 7.8 49.7 100 100 49.9 11.8 100 23.6
CH30C ii 0
H C*Z d2o


m 248 / V. ^ H C*4 d2o 13.0 247 248 249 250
100 16.4 1.25
0.025 26.3 100 53.1 12.8 100 24.2


81
A
P
P
e
n
d
i
x
2-B
cont.
nh2
H C*1 d2o


H 178 C14H10 2D
H C*2 d2o 13.93 176 177 178 179 180
100 15.3 1.09
0.031 39.4 19.9 100 51.9 39.4 100 75.9
CH30C ii 0
H C*3 d2o


ITI-CF3
H C*4 d2o




82
A
P
P
e
n
d
i
x
2-B
cont.
NH'
H
C*1
D20
H
H
C*2
D20
CH30C
ii
0
H
C*3
D20
m-CFj
H
C*4
D20
197
/
C14H15N \
NH2 CH CH3 X
4D
14.75
0.033
195 196 197 198 199 200 201
100 15.8 1.16
7.6 23.2 46.8 100 81.8 34.3 14.0
100 41.9


83
A
P
P
e
n
d
1
x
2-B
cont.
NH2
H
C*1
D20
197
/
C14H15N \
CH3 N
^-CH2-<0>
NH2 /
3D
16.56
0.264
195 196 197 190 199 200 201 202
100 15.8 1.16
6.2 21.2 47.9 100 97.8 46.6 12.0 2.3
100 25.7 4.9
H
C*2
D20
CH30C
11
0
H
C*3
D20
ITI-CF3
H
C*4
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84
Appendix 2 C
CF3 160 ^0)ch3 CF3 C8H7F3 3D
160 [32, M+], 141 [10,M+- F] 91 [100,M+-CF3]
158 159 160 161 162 163
100 8.76 0.34
OH B*2 h2o 2.23 0.100 4.5 31.8 100 7.7
A*2 d2o 2.23 0.053 22.0 85.1 100 37.1 7.1 100 18.7
H 92 <@>-CH3 C7H0 3D
92 [51, M+ ], 91 [100, M+-H]
89 90 91 92 93 94 95 96
100 7.64 0.25
OH B*3 h2o 1.95 0.321 100 50.7 6.1 0.006 100 12.1 1.3
A*3 d2o 1.94 0.145 1.6 3.4 17.8 86.9 100 52.5 15.5 2.2 100 29.5 4.2


85
Appendix 2 C (continued)
cf3 174 ^>-ch2ch3 CF 3 CgHgF3
174[25,M+], 159 [100, M+ ~ CH3] 155 [ 11 ,M+- F] 105 [18, M+- CF3 ]
174 175 176
100 9.87 0.43
OH B*2 h2o 3.13 0.017 100
A*2 d2o ND
H 106 -ch2ch3 C0H1O 4D
106 [24, M+ ], 91 [100, M+- CH3 ]
105 106 107 108 109 110
100 8.80 0.34.
OH B*3 h2o 2.76 0.000 21.3 100 19.1
A*3 d2o 2.74 0.026 30.7 100 58.3 26.2 100 44.9


86
Appendix 2 C (continued)




OH B*2 h2o
A*2 d2o
H 94 /\ (g/- oh C6H60 4D
94 [100, M+ ] ,66 [50, Cp- ]
94 95 96 97 98 99
100 6.62 0.38
OH B*3 h2o 4.27 0.009 100 10.9
A*3 d2o 4.13 0.062 91.3 100 16.5


86
Appendix 2 C (continued)
cf3



OH B*2 h2o
A*2 d2o
H 94 /\ <0)-OH C6H60 4D
94 [100, M+ ] ,66 [50, Cp- ]
94 95 96 97 98 99
100 6.62 0.38
OH B*3 h2o 4.27 0.009 100 10.9
A*3 d2o 4.13 0.062 91.3 100 16.5


Full Text

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NEURAL SELFTUNING ADAPTIVE CONTROL OF NON-MINIMUM PHASE SYSTEM DEVELOPED FOR FLEXIBLE ROBOTIC ARM By Long T. Ho B.S.E.E., University of Colorado, 1992 A thesis submitted to the Faculty of the Graduate School ofthe University of Colorado in paritial fulfilment of the requirements for the degree of Master of Science Department of Electrical Engineering 1994

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This thesis for the Master of Science degree by Long Thanh Ho has been approved for the Department of Electrical Engineering by Jan T. Bialasiewicz Miloje Radenkovic Marvin Anderson 2

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Acknowledgments The author wishes to express sincere appreciation to Dr. Jan T. Bialasiewicz for his guidance and joyful support during the course of this thesis. Also, enthusiasms of Dr. Miloje Radenk.ovic and Professor Marvin Anderson as the author's thesis committee are gratefully ackowledged. Special thanks to the author's family their never ending support. 3

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Ho, Long Thanh (M.S., Electrical Engineering) Neural Self-Tuning Adaptive Control Strategies of Non-Minimum Phase System Developed for flexible Robotic Arm Thesis directed by Professor JanT. Bialasiewicz The motivation of this research came about when a neural network direct adaptive control schemes were applied to control the tip position of a flexible robotic arm. Satisfactory control performance was not attainable due to the inherent non-minimum phase characteristics of the flexible robotic arm Most of the existing neural network control algorithms are based on the direct method and exhibit very high sensitivity if not unstable closed-loop behavior: Therefore a neural self-tuning control (NSTC) algorithm has been developed and applied to this problem and showed promising results. Simulation results of the NSTC scheme and the conventional self-tuning (STR) control scheme are used to examine performance factors such as control tracking mean square error, estimation mean square error, transient response, and steady state response. The form and content of this abstract are approved. Signed _ v Jan T. Bialasiewicz 4

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NEURAL SELF TUNING ADAPTIVE CONTROL OF NON-MINIMUM PHASE SYSTEM DEVELOPED FOR FLEXIBLE ROBOTIC ARM Table of Content 1. Introduction................................................................. 9 1.2. Neural Control Survey.............................................. 12 1.2.1. Stochastic Neural Direct Semi-Adaptive Control.. .... 13 Stochastic Neural Direct Adaptive Control.. ........... 15 1.2.3. Inverse Neural Adaptive Control........................ 15 1.2.4. Feedback Error Learning and Control.................. 16 1.2.5. Inverse Dynamic Model Reference Control of a Class of Nonlinear Plants ................................ 17 1.2.6. Neural Linear State Space Control.. .................... 18 1.2.7. Neural Self-Tuning Control.. ........................... 19 2. Stochastic Neural Self-Tuning Adaptive Control Scheme........... 21 2.1. Generalized Minimum Variance Control ..... ............. .. 22 2.2. Neural System Identification.................................. 23 3. Flexible Arm Tip Position Dynamics.................................. 28 4. Empirical Studies......................................................... 35 4.1. Neural Direct Adaptive Control of Ann Hub and Tip...... 35 4.2. Neural SelfTuning Adaptive Control of Arm Tip.......... 39 5. Conclusions .............................................................. 45 5.1 Future Research.................................................. 46 5

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6 Bibliography.................................................................. 47 APPENDIX A Simulation Program....................................... 49

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7 Figures and Tables Figures: 1.1 Flexible Arm System...................................................... 10 1.2 Specialized Learning Control of HupVelocity .......................... 11 1.3 Indirect Neural Adaptive Control Scheme.............................. 11 1.4 Adaptive control general block diagram................................. 13 1.5 Direct semi-adaptive control scheme ..................................... 12 1.6 Neural Network structure................................................ 14 1.7 Direct neural adaptive controller ......................................... 14 1.8 Inverse neural control..................................................... 15 1.9 Feedback error learning and control.................................... 16 1.10 Inverse dynamic model reference neural control...................... 18 1.11 Neural linear state space control......................................... 19 1.12 Stochastic neural linear ARMA control................................ 20 2.1 Neural Network Structure................................................ 25 3.1 Pole-Zero Diagram of Flexible Arm Tip ................................. 29 3.2 Servo Motor System Components ....................................... 30 3.3 Frequency Magnitude Response of Ann Tip with Five Resonant Modes 32 3.4 Frequency Response of Open-Loop Components ..................... 33

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3.5 Frequency Response of the Aggregate filtered Open-Loop ........... 33 4.1 Neural Direct Control Scheme of Hub Velocity....................... 36 4.2 Hub Velocity Response.................................................. 37 4.3 Control Tracking MSE Response .................................. ..... 37 4.4 Unstable Response of Tip Control.. ..................................... 38 4.5 Diverging Tracking MSE of Tip Velocity.............................. 38 4.6 NSTC Scheme Block Diagram........................................... 40 4. 7 Tip Position Response ....... .... ........................................ 42 4.8 Control Performance Index J(K) of the Adaptive STR andthe NSTC ........ ...................................................................... 43 4. 9 Control Signal u(k) of the adapteve STR and the NSTC .............. 43 4.10 Identification cost Index V(k) of the Adaptive STRand the NSTC .. 44 4.11 True and Neural Network Estimated Tip Position.................... 44 Tables: 3.1 Physical Properties of Arm and Motor ............................. : .... 31 3.2 Poles and Zeros ............................................................ 32 8

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CHAPTER 1 INTRODUCTION Most existing neuro control schemes are in the form ofthe direct method,. where the neural network is trained to approximate the inverse of the plant. In the case where the plant is non-minimum phase, the inverse approximation introduces instability in the closed-loop system. Therefore, an indirect neuro control scheme is proposed to deal with non-minimum phase systems. we propose to use a neural network to identifythe plant parameters, then combine this with a minimum variance control law. The plant in this study is a single degree of freedom flexible robotic ann. Self-tuning adaptive control used for controlling unknown ARMA plants has. traditionallr been based on the minimum variance control law and a recursive identification algorithm (Astrom and Wittenmark, 1973; Clark and Gawthrop, 1979). Although the advancement in VLSI has made it more possible to implement real-time recursive algorithms but it is still computationally intensive and expensive due to the recursive nature of algorithm. On the other hand;. neural networks VLSI has been made available commercially with extreme processing capability due to its parallel With this in mind the possibility of formulating neural networks to perform functions of conventional recursive algorithms becomes important. Hence, in this thesis, the neural self tuning control (NSTC) scheme is used where the implicit identification is performed by a multilayer neural network (MNN) and the control is based on the generalized minimum variance (GMV) control.law. Neural networks have undoubtedly demonstrated its effectiveness in controlling nonlinear systems with known/unknown dynamics and uncertainties (Narendra and Parthasrathy, 1990; Levin and Narendra, 1993; Werbos.et al. 1990; Hunt et al., 1992). In addition, neural network adaptive control algorithms have also been developed for spec"ific linear system model such as the state space model (Ho et al., 91a) and the ARMA model (Ho et al., 1991b). It was shown in the simulation results that neural network controllers produced comparable results to conventional adaptive controllers. 9

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In this thesis, the performance of the NSTC is compared to the conventional adaptive STR. The flexible arm to be controlled is shown in Figure 1.1. There are two system outputs that are of interest, one is the hub angle 8h(t) and the other is the tip angle 8t(t) of the arm. The goal is to apply a neural network control scheme to control these outputs to the command signals. The neural controller will generate a control voltage signal u(t) that will feed the power amplifier in which will force current through the motor and cause the arm position to react. The dynamical transfer function of the hub angle is a linear minimum phase system in which will be shown readily controllable by a neural network. In fact, the direct adaptive neural control scheme in Figure 1.2. can be used to control the hub. This control scheme belongs to the type called speCialized learning control (Psaltis et al., 1988; Ho et al., 199lc). However, the tip of the arm, being at a different location than the actuator point, therefore making the system to be of the type non-collocated system. The effect of this dynamically is that there is a zero in the right half of the s-'plane. In other words, the transfer function of the tip angle is of the non-minimum phase type which presents itself to be very difficult to control when direct adaptive control methodologY is applied. This difficulty may be due to the controller trying to emulate the inverse dynamics of the non-minimun phase plant and results in an unstable behavior. According to simulation studies, the specialized leani.ing control algorithm diverges when applied to control the tip angle. _Most otherneural control schemes are also based on the inverse dynamics including the indirect learning method by (Psaltis et al., 1988), the feedback error learning by (Kawato et al., 1988), and the methods presented by (Narend'ra and Parthasarathy, 1990): payload tip angle ...... e h hub angle ....... motor ...... ...... ...... ...... ...... ...... ...... ...... ...... Figure 1.1. Flexible arm system 10

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aeh(k) Sh(k) Neural Network u(k) -Controller Flexible Arm -Sh(k) E Figure 1.2. specialized learning control of hub velocity tip position u(k) St(k) = y(k) ....... Tip of Flexible Robotic Arm 8 ; ...... 3-Layer Neural Network Identification ...... -!" "' 81(k) =y(k) 1\ t '" 8 1..., Generalized Minimum Variance Controller -..... )" St (k) = y*(k) desired output Figure 1.3 Indirect neural adaptive control scheme In this thesis, the neural self tuning control scheme which is based on an indirect control method (Ho et al., 1991c) to control the tip angle. This scheme is 11

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shown in Figure 1.3 where the identification is performed by the MNN and the control is performed by the generalized minimum variance (GMV) controller. The GMV control algorithm has a dynamic weighting function Q(q-1) applied to the plant control signal u(k) in the cost function to limit and condition the control energy. Thus, upon selecting the proper weighting function the controller can be input/output stable and effective in controlling the non-minimum phase plant. In section 2, the neural self tuning control (NSTC) which consists of the minimum variance control algorithm and the neural identification is presented. Section 3 covers the basic dynamics of the flexible arm tip position. Section 4 presents a comparative simulation study of the adaptive STR scheme and the NSTC scheme. Finally, section 5 gives the conclusion of the results found in this study and addresses the advantages and disadvantages of the neural control scheme used for treating linear system. 1.2 Neural Control Survey In the past five years neural network based adaptive control has been a proliferated and challenging field for researchers in the area of adaptive and nonlinear control As technology advances and more and more dynamical systems emerge with high degree of complexity in coupled and nonlinear characteristics, conventional modern and adaptive control techniques are showing to be less and less effective in achieving demanding control performance .. This is partly due to the fact that many of these systems are linearized and decoupled beforehand in order to apply conventional control techniques, which consequently causes inaccuracies in representing system dynamics and therefore looses effectiveness in controlling the system. Neural network based adaptive control (NNBAC) has shown to have some unique and superior capabilities in controlling stochastic nonlinear time varying systems mainly because neural networks can model nonlinear complex processes more accurately. Furthermore, due to the inherent parallel structure of neural networks NNBAC offers the major computational load advantage because of parallel computations. Hence, implementation is more possible in cases dealing with large scales and/or high bandwidth systems where sufficiently fast sampling rate is required. In this section, we briefly present a survey of existing neural control schemes. Consider the general block diagram of an adaptive control scheme shown in Figure 1.4. Now, an adaptive control scheme may assume no a priori knowledge of the plant, but an effective and prudent adaptive control scheme should utilize and exercise all the a priori knowledge that is available. Some of the early neural control 12

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schemes such as the inverse indirect learning and the specialized learning were impressive because these schemes required very little a priori information about the nonlinear plant and treated it like a "black box". Input u(k) Disturbance Plant Identifier Output y(k) Figure 1.4. Adaptive control general block diagram 1.2.1 STOCHASTIC NEURAL. DIRECT SEMI-ADAPTIVE CONTROL Consider the first scheme called the stochastic neural direct semi-adaptive control shown in Figure 1.5 (Ho et al., 1991c). This scheme is the stochastic weighted version of the specialized learning (Psaltis et al., 1988) and is formulated with the well known weighted optimal control cost function J(k) = t E{ [y(k)-y*(k)]'Q[y(k)-y*(k)] + u(k)'Ru(k)} ( 1.1) 13

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()y/()u y*(k) controller desired output Figure 1.5. Direct semi-adaptive control scheme This control scheme is based on the nonlinear stochastic state space model x(k+ 1) = f[x(k)] + B(k)u(k) + w(k) y(k) = C(k)x(k) + v(k) (1.2) The a priori infonnation required for this scheme is.the input/output dynamic matrices B and C. This is so that the plant jacobian ay(k)au(k) can be computed and used in the back propagation algorithm. Figure 1.6 shows the typical structure of a multilayered neural network. INPUT DELAY NETWORK OUTPUT Figure 1.6. Neural Network structure 14

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1.2.2. STOCHASTIC NEURAL DIRECT ADAPTIVE CONTROL This scheme is almost identical to the previous scheme (Ho et al., 199ld) except that it has no a priori information about the plant input/output dynamics. Therefore it incorporates an additio.nal neural network so that the plant jacobian can be estimated. The block diagram of this scheme is shown in Figure 1.7 where the plant was basicaily treated to be a "black box" nonlinear system with the general state space form x(k+l) = f[x(k),u(k)] + w(k) y(k) = g[x(k)] + v(k) y*(k) desired -.....--output /' aytau noise estimation error Figure 1.7. Direct neural adaptive controller 1.2.3. INVERSE NEURAL ADAPTIVE CONTROL (1.3) This is one of the first neural adaptive control schemes known as the indirect learning proposed by (Psaltis et al., 1988) and is shown is Figure 1.8. The plant is assumed to be a "black box" nonlinear system y(k) = f[y(k-1), ... y(k-n); u(k), ... u(k-m)] (1.4) 15

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Plant input estimation errore(k) Figure 1.8. Inverse neural control Here, the two neural networks at the input and ouput of the plant are identical. The network is to emulate the inverse of the plant based on optimization of the cost function J(k) = [u(k)-u(k)]'[u(k)-u(k)] (1.5) which indirectly minimizes the output tracking error [y(k)-y*(k)]. 1.2.4. FEEDBACK ERROR LEARNING AND CONTROL (FELC) This direct adaptive control method proposed by (Kawato et al. 1988) may be one of the most efficient "black box" neural control scheme as shown in Figure 1.9, the scheme utilizes a single neural network as an adaptive direct controller performing both learning and control simultaneously. error Figure 1.9. Feedback error learning and control e (k) c 16

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The neural network directly minimizes the output tracking error cost function J(k) = t[y*(k)-y(k)]'Q[y*(k)-y(k)] (1.6) and does not require any a priori infomation such as the Jacobian. 1.2.5. INVERSE DYNAMIC MODEL REFERENCE CONTROL OF A CLASS OF NONLINEAR PLANTS This approach was presented by (Narendra and Parathasarathy, 1990) addressing the issues of identification utilizing neural networks and control of nonlinear plant using inverse dynamic model reference techniques. The general diagram of this scheme is shown in Figure 1.10. The four input/output plant models addressed are Modell: n-1 y(k+l) = L aiy(k-i) + g[u(k), u(k-1), ... u(k-m+1)] i=O (1.7a) Modelll: m-1 y(k+1) = f[y(k), y(k-1), ... y(k-n+1)] + L i=O ( 1.7b) Model ill: y(k+l) = f[y(k), y(k-1), ... y(k-n+1)] + g[u(k), u(k-1), ... u(k-n+1)] (1.7c) ModelN: 17

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y(k+l) = f[y(k), y(k-1), ... y(k-n+1); u(k), u(k-1), ... u(k-n+1)] ( 1.7d) r(k) model input Inverse dynamics controller /\ A f(.), g(.) Reference model Plant Type J,JJ,IIJ,IV Neural networks identifier Qr tracking error e tk) estimation error e jk) Figure 1.10 Inverse dynamics model reference neural control The a priori information required is which of these specific model fits the plant so that identification can be performed. However, the inverse dynamic control can be accomplished provided the representation of the inverse dynamics exists. In other words, it is recognize that u(k) can be expressed in terms off(.), g(.), f-1(.) and g-1(.). 1.2.6. NEURAL LINEAR STATE SPACE CONTROL This scheme shown in Figure 1.11. (Ho and Ho, 1991 a) is used for controlling time varying linear stochastic state space plant x(k+l) = A(S,k)x(k) + B(S,k)u(k) + w(k) y(k) = C(S,k) + v(k) (1.8) where 8 is the parameter vector. The identification is performed by the neural network and the control can be selected by any modern state space control techniques, in 18

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particular, the tracking per-interval control law. This neural parameter adaptive control approach is different from the conventional adaptive control approach by the identification process. y*(k) desired output State space controller A A e, x Plant Neural network identifier estimation error e I Figure 1.11. Neural linear state space control 1.2.7. NEURAL SELF-TUNING CONTROL This scheme, shown in Figure 1.12. (Ho et al, 1991b) is similar to the state space control scheme only it is based on the ARMAR plant model B(q-1) C(q-1) y(k) q-d u(k) + A(q-1) A(q-1) (1.9) The identification is performed by the neural network arid the control can be selected by any conventional control techniques, in particular, the minimum variance control. This neural self-tuning control scheme is different from the conventional self-tuning control by the identification algorithm. 19

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y*{k) desired output Minimum Plant H(s) Neural network identifier error Figure 1.12. Stochastic neural linear ARMA control 20

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CHAPTER 2 STOCHASTIC NEURAL SELF-TUNING ADAPTIVE CONTROL (NSTC) The NSTC consists of the minimum variance control law and the neural identification algorithm. The model assumed for the plant is of ARMA input/output type having the form (2.1) where u(k), y(k), and d are systein input, output, uncertainty, and delay, respectively. A, B, and Care unknown system dynamics defined as A( -1) 1 -1 -2 -na q = + a1 q + + ... + anaq B( -1) b b -1 b -2 b -nb q = 0 + lq + 2q + ... + nbq C( -1) 1 -1 -2 -nc q = + c 1 q + c2q + ... + cncq (2.2) (2.3) (2.4) where q is the shift operator. For the above unknown plant, in Figure 1.3, the objective is to control its output to track a command signal y*(k) based on the generalized minimum variance control index (Clark and Gawthrop, 1979) J(k+d) = E{ c!>2 (k+d)} = E{ [P(q1 )y(k+d)+Q(q1 )u(k)-R(q1 )y*(k)] 2 } = E{ [(j>y(k+d)+Q(q-1 )u(k)-R(q1 )y*(k)]2} (2.5) where E is the expectation operator, c!>yCk+d) is the auxiliary output, and P,Q, and Rare the weighting dynamics which can be chosen depending on the required response characteristics. 21

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2.1. Generalized minimum variance control In this section, the generalized minimum variance self-tuning control algorithm for the above problem statement is summarized (Clark and Gawthrop, 1979). To obtain the optimal control u(k) which minimizes the performance index (2.5), the predictive auxiliary output c!>y(k+d) in terms of the system dynamics must be determined. Consider the following identity (2.1.1) where the order ofF(q-1) and G(q-1) are nf;:d-1, ng=na-1, respectively. The output prediction can be shown to have the form where and = C(q-1f1 [G(q-1)y(k) + F(q-1)B(q-1)u(k)] = C(q-lf1 [G(q-l)y(k) + E(q-l)u(k)] = 1\ (2.1.2) (2.1.3) (2.1.4) c!>yCk+d) and c!>yCk+d) are the deterministic and uncorrelated random components of c!>yCk+d). Next, substituting (2.1.2) into (2.5), there results (2.1.5) Since the second term in (2.1.5) is unpredictable random noise which is uncompensatable by the control input u(k), and the first term is a linear function of u(k), J(k+d) can be minimized by setting 22

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(2.1.6) Solving for the generalized minimum variance control (GMVC) in (2.1.6) gives R(q1 )y*(k)-$y(k+d) u(k) --------.-..J..--Q(q-1) using (2.1.3), (2.1.7) can also be written as u(k) = C(q -1 )R(q -1 )y*(k)-G(q -1 )y(k) E( q -1 )+C( q -1 )Q( q -1) (2.1. 7) (2.1.8) Remarks: Recall that E(q-1) is equal to F(q-1)B(q-1) where B(q-1) contains the zeros of the plant. Notice that having the weighting function Q(q-1) additive to E(ql) in (2.1.8) gives the designer the ability to alter the poles of the controller. Thus with a non-minimum phase plant B(q-1) shall have unstable roots and proper selection of Q( q-1) in (2.1.8) can assure the control signal u(k) to be bounded. 2.2. Neural system identification In this section, a stochastic neural identification algorithm is developed for the self-tuning control scheme in Figure 1.3. Recall the predicted auxiliary output in (2.1.3) which can also be written as cJ>y(k+d) = C(q-If1 [G(q-l)y(k) + E(q-l)u(k)] + = C(q-If1 [G(q-l)y(k) + E(q-l)u(k)] + v(k) (2.2.1) where the uncorrelated noise sequence is by v(k). Also (2.2.1) can be written as (2.2.2) c!>yCk+d) = \jl'(k)9(k)+ v(k) (2.2.3) where 23

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\jl'(k) = [y(k) ... y(k-ng); u(k) ... u(k-ne); (k+d-nc)] (2.2.7) A AA A AA A AA A 9 '(k) = [go g 1 gng; eo e 1 ene; -c 1 -c2 -cncl <2 2 8 ) The unknown parameter vector in (2.2.8) (Figure 2.1), is taken from the output of the neural network A A A 9(k) = [ til (k) t12(k) ... 9j(k) ... en.3(k)l' = [01 (k) 02(k) ... Oj(k) ... On3(k)]' (2.2.9) Where n3 is the number of neurons at the output layer. Consider the system identification cost function V(k) =!E{E'(k)A-1(k)E(k)} =! E{[tj>y(k)-$y(k)]'A-l(k)[$y(k)-$y(k)]} (2.2.10) where A(k) is a symmetric positive definite weighting matrix, and V(k) is minimized by adjusting the weights of the neural identifier. 24

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NEURAL NE1WORK Figure 2.1. Neural network structure In Figure 2.1, the weights connecting the second layer to the output layer, using the gradient search (Rumelhart and McClelland, ), can be updated as ffiij(k+l) = ffi:ij(k) (2.2.11) where () 1 1 AOlij"(k) ::: -11 { 2 E'(k)A(k)E(k)} dffiij(k) = -11 () { dffiij(k) YJ YJ = 11 A-1(k)[cj> dffiijCk) Y YJ (2.2.12) with 11 being the search step size. Consider the derivative of c!ly(k) with respect to in (2.2.12) (2.2.13) In (2.2.13) we have assumed that 9(k) 9(k-d), that is, 9 is slowly time varying with respect to the delay time d. The other partial derivative in (2.2.12) can be determined as = O(k)e d[f(Netj(k))]' dffiij(k) 1 J dNetj(k) (2.2.14) 25

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where f(.) is the sigmoidal activation function, Oi(k) is the output of the second layer, and with Netj(k) = [nell net2 ... netj ... netn3l' n2 netj(k) = LCOij(k)Oi(k) i=1 (2.2.15) where n2 is the number of neurons of the second hidden layer as shown in Figure 2.1. Also ej in (2.2.14) is defined as ej = [0 ... 0 1 0 ... 0] (2.2.16) with the j-th element in ej being 1, and other elements are 0. Thus, substituting (2.2.14) back into (2.2.12) gives (2.2.17) where 1\ (k) = d[f(Netj(k))]' dcl>y'(k) A-l(k)[q, 0J aNetj(k) ae(k) Y (2.2.18) Next, the weights connecting the first to the second layer, in Figure 2.1, can be updated by the recursive equation ronCk+ 1) = ronCk) + L\OJri(k) (2.2.19) where d 1 1 dffiri(k) = -11 { 2 E'(k)A(k)E(k)} dffiri(k) (2.2.20) Using the similar back propagation approach, (2.2.20) can be shown to result in the following form (2.2.21) where Or is the output of the first layer and 26

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df[neti(k)] Oi(k)=[Olil...Olij ... ffiin3] dneti(k) Oj(k) (2.2.22) Lastly, the weights connecting the input to the first layer, in Figure 2.1, can be updated by the recursive equation Olsr(k+ 1) = Olsr(k) + Arosr(k) (2.2.23) where a 1 1 Arosr(k) = -11 { 2 e'(k)A(k)E(k)} dOlsr(k) (2.2.24) Again, using the back propagation approach, (2.2.24) can be detennined as Arosr(k) = 'JlOr{k)Is(k) (2.2.25) where Is(k) is the input from the delay network and df(netr(k)) d[f(Neti(k))]' aNetj(k)' Or(k) = [Olrl...Wri ... rorn2] anetr(k) aNeti(k) a[f(Neti(k))]' Oj(k) (2.2.26) with Neti(k) being defined similarly as Netj(k) in (2.2.14). By adjusting the weights Olij(k), Olri(k), and Olsr(k) with the above algorithm, the unknown implicit plant's parameters can be identified and obtained at the output of the neural identifier, as shown in Figure 2.1. Once the estimate of 9 is available, PyCk+d) in (2.2.6) can be computed, and then the control signal can be generated using (2.1.7) as R(q1 u(k) ------.--L--Q(q-1) (2.2.27) 27

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CHAPTER 3 FLEXIBLE ARM TIP POSITION DYNAMICS This chapter describes the components and the control model of the flexible arm tip. A detailed discussion of the dynamics of flexible arm tip and hub can be found in (Fraser and Daniel, 1991). In order to control the flexible robotic arm shown in Figure -, .. -.-1.1, it is required that the control action produced by the control program running on a processor board is converted to a voltage by the D/A board and forms the input to the power amplifier of the motor. The otltput of the power amplifier is a motor current directly proportional to the input voltage. The motor then converts this current to a torque to drive the arm. The resulting motion of the arm is detected by the various sensors and fed back to the controller. The adaptive control algorithm design does not require the complete knowledge of the plant dynamics. However, for the purpose of simulation study, the transfer function model of the plant needs to be known. This model must incorporate not only the behavior of the flexible arm itself but also the power amplifier, the motor and the output sensors. In a servo system, the power amplifier and the sensors usually have a much higher bandwidth than that of the motor and load therefore they can be approximated as a constant. The general transfer function of the flexible arm tip is 9t(S) = KAKT fl u(s) s(s+co) i=I where the physical interpretation of the above equation is as follows: First, poles and zeros of the system is depicted in Figure 3.1 (3.1) 28

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X X .... X X resonant modes s-plane motor dynamics flexible ami minimum and non-minimun phase zeros Figure 3.1 Pole-zero diagram of flexible arm tip The above diagram shows the three constituting dynamic components of the plant which are the motor, the resonant modes of the flexible arm, and the arm non-minimum phase characteristics. The dynamics of the servo motor system is represented by the term (3.2) where Ky. is the motor torque constant, K A represents the power amplifier and sensor gain, and C0 represents the back emf and viscous damping effects know as the mechanical time constant. The motor can be seen as a series of subcomponent connected in series as shown in Figure 3.2. 29

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motor motor velocity position voltag:-1 I torq:l ' _I_ I I ._l I KA KT (s+co) s Figure 3.2 Servo motor system components Next, the the flexible arm attached to the motor shaft is describe by the term. (3.3) Here, the of (3.3) represents the set of flexible resonant modes of the aim. Each flexible mode is associated with the corresponding damping at a frequency Olj. Theoretically, there is an infinite number of flexible modes, but in practice only the sufficiently low frequency modes will be noticeable by the control system. This is because a real system is always band-limited. Therefore most of the modes are attenuated by the low-pass frequency behavior. Also, the frequency range of operation can be limited to be below-the inajor do.minant resonant mode so that oscillations will not be. present in. the system response. If higher frequency range of operation is desired, the dominate resonant modes can be notch filtered out provided their damping and frequencies Olj'S are determinable, Consider the physical properties of the flexible arm and the servo system given in Table 3.1. Based. on these parameters the transfer function was derived and measured by experiment (Fraser and l)aniel, 1991) .. Both results agreed as shown in Table 3.2. The five resonant modes occupy the frequency range from 86 rad/sec to 1445 rad/sec. The frequency response of this system was simulated and is shown in Figure 3.3. The peaks represent the resonant energy at the specific freqQencies. Also notice that the energy of the modes lessens are the frequency increases. 30

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31 Table 3.1. Ph I IYSICa r proper 1es o f arm an d motor effective beam lenath Jm) 0.386 beam thickness (mm) 0.956 .... beam width .. 0.03 mass/unit length of arm m (kg/m) 0.222 flexural rigldity of beam(NmA2) 0.426 hub moment of inertia (kg mA2) 0.00009 radius of hub (m) 0.034 Tip mass for loaded arm (ka) 0.065 tip inertia for. load arm (kg mA2) 0.000.005 continous torQue at rated speed (Nm) 0.177 pulse torque(Nm) 2.913 rated voltaae (V) 24 torQue constant (Nm/A) 0.048 total inertia (ka mA2) 0.000041 Ka*Kt 3.6 Co (rad/secl 0.16

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Table 3.2. POLES (rad/sec) ZEROS (rad/sec) Mode Expmt. Theory Expmt. Theory 1 86.1 86.9 48.4 47 2 297.6 285.3 -48.4 -47 3 603.2 60L9 4 1011.6 1065.0 5 1445.1 1658.8 20 r---:--c.----:-. -:-. -:-. -:-.:-:-. -:-. --;-----,,;--;-, -:-. -:-. -;-, -:-;-, -;-, ----:.-.,,.......,..--, .---:.--;-. --,..., ,,....,.. ----..,...--,----,--.,........,....,-,--,-, .... .. . ...... . .. '. . . . . . . . . . . o : ne<: -20 ....... ... :. .. : .. : : : ...... : ... : .. :.-: .. : ...... ... : ... : : :::::::: ::::::::: ::::::::h .. :: : : j : IT][ iii 1 ][iiiiL L[ il:tlll \ I I I ....... _! .... .. 1"[ .. : :t ...... : .... : .. : .. f r i j-:-.... : .... : .. : : i ..... \ t ... : : -100 ....... ... : .. .. : .. : ...... .... ; .. > >: ...... : .... .. : ::-:...... .. \ .... : . : 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -120 ....... ; ... .; .. : .. ; .. ;. ...... :-...; ... ; .. .;.:: .; ....... ; .... .. ; :-: .;. :.;.; ....... ... : .... ; ... ;. 100 lOt 102 Radianls 103 Figure 3.3 Frequency magnitude response of arm tip with five resonant modes 104 32

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For easy controllability it is desirable to filter out these resonance modes. Therefore, a notch filter is designed to notch out the first resonance mode and a low pass filter is used to filter out the rest of the resonance modes. Figure 3.4 shows a block diagram of the filtering process. The resulting frequency ideal response is shown in Figure 3.5. notch filter LP filter flexible arm system voltage .__ _____ __. Figure 3.4. Frequency response of open-loop components Tip position 0 Q ......... ; ..... .... : .... : ... ;.; .. ......... : ... . . o 0 o o o I 0 .g .a : : : : : : : :: : : .. : : : : : :: : : : : : : : :. :: :: : : : : :::: : : : -100 ........ ; .. ".: .... : ... : .. :. .:. : ....... .-:.... : ... : .. :.:. ;, ; .: ;_"" .... : .... ,; ".: .. . 0 0 -150 ......... ; ..... : .... : ... : .. > -:........ -:... ... : .. -:-:-" "." -:... ... 0 0 0 0 0 0 0 . . . . . . . . . . . . . . . ::\ 101 102 103 104 Radian/s Figure 3.5 Frequency response of the aggregate filtered open-loop 33

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Since we are primarily interested in learning the controllability and behavior of the non minimum phase characteristics of the plant, we can simplify the arm tip transfer function to have the form (3.4) Lastly, the non-minimum characteristics of the ann tip is describe in (3.1) and (3.4) by the numerator term. This is due to the fact that the control system sensing and actuation do not take place at the same location and therefore being a non-collocatted system. It should be mentioned that the non-minimum phase characteristics is very difficult for the neural network to control (since most neural network adaptive control schemes are based on the direct method). 34

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CHAPTER 4 EMPIRICAL STUDIES In this chapter we examine some simulation results of the direct and indirect neural control schemes for controlling the flexible arm hub and tip. We will show that the hub having a well behaved linear transfer function produced very satisfactory controlled response; We also attempted to use the direct adaptive control scheme to control the tip velocity and found unstable response even after numerous controller parameter changes. Next, the NSTC scheme in section 2 was applied to control the tip position and produced encouraging results. Lastly; the neural identifier in the NSTC algorithm is compared with the recursive least square identifier and show faster . convergent rate. The simulation program used in this study is given: in the appendix. 4.1. Neural direct adaptive control of arm bub and tip The neural direct adaptive control scheme was frrst introduced by (Psaltis et al., 1988) and was Jater reformulated for nonlinearninear state space system by (Ho et al., 1991c). We will apply this scheme, shown in Figure 4.1. to control the hub velocity of the arm. The dynamic function of the hub is a linear minimum phase system. The numerical transfer function found in (Fraser and Daniel, 1991) is s2 9 ( ) 10.2 ( 1 I ) h s 32.72 U(s) (s+0.57)(s+2000) (4.1) 35

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aeh(k) 8h(k) Neural Network u(k) -Controller Flexible Ann -8h(k) '\ E Figure 4.1. Neural direct control scheme of hub velocity where the resonant modes are assumed to be filtered out. In the simulation process, the model in ( 4.1) was first discretized and then converted to state space form x(k+1) = Ax(k) + Bu(k) (4.2) 8h(k) = Cx(k) When using this scheme (Figure 4.1.) there is a priori information that is needed and aeh(k) that is the jacobian of the plant au(k) This term was computed based on the discretized model and resulted as aeh(k) = cs du(k) (4.3) Information on the neural network algorithm is refered to (Ho et al., 1991c). Remarks: : The hub position was not suitable for this specialized learning control scheme because the jacobian turns out to be near zero. Therefore the velocity is the selected controlled variable and an additional outer control loop may be incorporated to achieve position control. This outer loop will have a velocity profile generator which resembles to a proportional controller with saturation (Franklin and Powell, 1981 ). Simulation: A smoothed square wave command was presented to the control system, after 50 iterations (about .3 seconds, sampling period was 6 ms) the hub had tracked the command signal as shown in Figure 4.2 where the solid line is the desired response and the dashed line is the actual response. 36

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./: . . 0 I ...... ....... ....... ... --. -.. -.. .. --.. -. ... --.... ---:........ '1:' .. '> . . . . . . . . . . . . . . . . 0 50 100 150 200 250 300 350 400 450 500 Iterations "' Figure 4.2. Hub velocity response: St (k) & St(k) This trackability is reflected in the mean square tracking error_ shown in Figure 4.3. Notice that the convergent time in control application is serveral orders of magnitude faster than other applications. In this case it took only 50 iterations for the 2-layer neural network to be maturely trained with initial random weights. This fast convergent time makes it very practical for real-time control irriplementation; 0.2 ;:;;;;-0.1 '-' ..... 0 0 50 100 150 200 250 300 350 400 450 500 Iterations Figure 4.3. Control tracking MSE response Next, the same scheme is applied to control the tip velocity. The numerical tip transfer function (based on the flexible arm and motor properties in Tables 3.1 and 3.2) is given in (Fraser and Daniel, 1991) as 3.6 (11 s2 ) St(S) 48.42 U(s)-s(s+0.16) (4.4). 37

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Here again, we are primarily interested in the non-minimum phase characteristics and . therefore assumed that the resonant modes are filtered out. Simulation: After numerous attempts to vary the neural network parameters, an unstable closed-loop response was prevalent as shown in Figures 4.4 and 4.5._ This is due to the fact that the neural network in Figure 4.1. trying to emulate the inverse dynamics of the plant (4.4.) and in effect produced an unstable pole behavior. Note in Figure 4.4. that the command signal is small compared to the plant diverging output response therefore it looks like a straight line. :,,._ e . . ...... . ;;.... 0 ......... : ......... : ......... ; .,, ..... : ......... .; ___ ........ ...... : ......... : .. :.... . -: 0 0 0 : : I ....._ :_\ r / _______________ : 0 50 100 150 200 250 300 350 400 450 500 Iterations . Figure 4.4. Unstable response of tip control: 8t*(k) and 8t(k) 3ooo L ! rI:I: : :: :. v : : . . . . . . . 0 : : : 0 0 : : 0 50 100 150 200 250 300 350 400 450 SOD Iterations Figure 4.5. Diverging tracking MSE of tip velocity N2 Neural Network: The 5,10,1 neural network used in this scheme consists of one input layer, one hidden layer, i;ind one output layer with the number of neurons as 5, 10, and 1, respectively. Also at the input of the neural was the desired response vector [y*(k) y*(k-1) y*(k-2) y*(k-3) y*(k-4)]T. The parameters of the sigmoidal activation function at the output node were found to be most influential on the tracking error convergentce 38

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rate. Predominantly the slope of the activation function was observed to be proportional to the convergence rate. Also the bipolar sigmoidal saturation levels of the output neuron needed to be set equal to or greater than the maximum allowable plant input. The tuning of the sigmoidal functions was done manually by trial and error, typically for linear system like that of the hub, it takes very few tweaks (around 1 or 2) before the tracking result was achieved. Auto-tuning of the sigmoidal function parameters can also be applied to obtain statiscally better results (Yamada and Yabuta, 1992; Proano, 1989). 4.2 Neural self-tuning adaptive control (NSTC) of tip position In section 4.1. we showed by simulation that the direct neural adaptive control scheme was unable to control the tip position (Figures 4.4 and 4.5). In fact, this was why the NSTC algorithm was Recall that this scheme has two distinct functions, identification and control, which are done by the neural network and the (GMV) control, respectively. The NSTC scheme is shown again in Figure 4.6. 39

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tip position u(k) 6t(k) = y(k) "Tip of Flexible Robotic Arm ,.. e +' f'e(k) ; .. _J, "'3-Layer Neural Network Identification ""' -,. ..,.... 6t(k) =y(k) t l.....r Generalized Minimum Variance Controller "' et (k) = y*(k) desired output Figure 4.6. NSTC scheme block diagram In this section we perform the simulations of two schemes which are: The adaptive STR using recursive least square identification, and the NSTC using the neural identification. This was done to performis a comparative study in order to assess the performance of the developed NSTC. Simulation: The model of the tip position is the discretized model of ( 4.4). Recall the control index defined in section 2 J(k+d) = E{ cp2 (k+d)} = E{ [P(q1 )y(k+d)+Q(q1 )u(k)-R(q1 )y*(k)] 2 } (4.5) where the weighting functions were chosen as 40

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P(q-1 )=1; Q(q-1 )=.1 +.06q-1; R(q-1)=1 (4.6) and the desired hub position 8t (k) was a step command. Beginning with Figure 4.7. shows the desired step tip response, the controlled tip response based on the adaptive STR and the tip response from the NSTC. Obviously both controllers manage to track the command signal. However, the NSTC seems to have a slower settling time. Figure 4.8. shows the converging tracking control index (2.1.5) where both schemes seem very comparable to each other. Figure 4.9. displays the comparable control energy produced by-tliese.controlieri. Note that tlie transient control energy was ...... affected by two factors: one is the initial condition of the estimated parameter vector 8o ...... ...... (which was set as 8o = [1 1 ... 1]' for both control schemes), the further 8o is away from the optimum 8 in the parameter state space, the longer the convergence of the tracking control index (2.1.5). The other factor is the selection of the input weighting function Q( q-1) which has the effect of limiting the control energy with the tradeoff of slower tracking convergence. Lastly, we compare the recursive least square identification with the neural network identification. The two identifiers estimate the parameter vector e in (2.2.5) so that the predictive output term cj}y(k+d) in (2.2.2) can be computed. Figure 4.1 0. shows the estimation cost function V (k) in (2.2.1 0) response of the RLS and the neural network. V(k) of the RLS has a slightly faster convergence than the neural network but not by a significant degree. Again, this indicates that the identification performance of the two algorithms are comparable to each other. For completeness, the time response of the true output 81(k) and the estimated output 8t(k) produced by the neural network is shown in Figure 4.11. Neural Network: The three layer neural network Nts.I5,PO used in this scheme consists of one input layer, two hidden layers, and one output layer with the number of neurons as 2, 5, 15, and PO, respectively. PO is the length of the vector defined in (2.2.8) which is (ng+ 1 )+(ne+ 1 )+nc, and is 11 for the case of the arm tip plant. The input of the neural network was a selected as constant vector Is= [1 1]' because it was desired that the output of the neural network to be correlated to the its input. The parameters of the sigmoidal activation function at the output node was found to be most influential on the tracking error convergent rate. Predominantly the slope of the activation function was observed to be proportional to the estimation convergent rate V(k). Also the bipolar sigmoidal saturation levels of the output neuron needed to be set equal to or greater than the maximum component of the parameter vector 8. The tuning 41

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of the sigmoidal functions was done manually by trial and error. Autotuning of the sigmoidal function parameters can also be applied to obtain statiscally better results (Yamada and Yabuta, 1992; Proano, 1989). However, the optimal dimension of the neural network in terms of number of layers and nodes was not known and therefore an N3 initial pick of 2,5,15,PO was used throughout the simulation. 1 0 I r I II -1111 ,u ,w Adaptive STR --NSTC 0 0.5 1 1.5 2 2.5 3 Time (sec) Figure 4.7. Tip position response: 6t (k)" & 6t(k) of the adaptive STRand the NSTC 42

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8 6 4 2 0.5 1 Adaptive STR --NSTC 1.5 Time (sec) 2 2.5 Figure 4.8. Control performance index J(k) of the adaptive STR and the NSTC 50 40 II ,, l1 30 /I I\ 20 /I I I I 10 I 0 1 -10 0 /: N I \I ,, 0.1 ' 0.2 Adaptive STR --NSTC 0.3 Time (sec) 0.4 0.5 Figure 4.9. Control signal u(k) of the adaptive STRand the NSTC 3 0.6 43

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2.5 I II\ 2 \ I I I I I 1.5 : \ I I I l r n. \ I I I 0.5 7 Adaptive STR --NSTC 0.5 1 1.5 2 2.5 Time (sec) Figure 4.10. Identification cost index V(k) of the adaptive STR and the NSTC -3 I ll -------... ---1 -1 --estimated hub position -2 actual hub position -3 -4 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (sec) Figure 4.11. True and neural network estimated tip position: 9t(k) & 9t(k) 44

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CHAPTER 5 CONCLUSION The neural self-tuning control (NSTC) algorithm was developed and applied to control the tip of a flexible ann system. The dynamics of the flexible arm tip involves an unstable zero and therefore making the system non-minimum phase. Most of the existing neural adaptive control are based on the inverse dynamics and therefore would not be able to control this type of plant. The NSTC was based on an indirect control method where the identification is performed by the neural network and the control was based on the generalized minimum variance (GMV) control law. The performance of the NSTC was investigated and was compared to the adaptive STR by means of simulation. In summary, the NSTC has a very comparable performance to the adaptive STR shown by simulation results in section 4.2. Unlike other applications of neural networks where thousands of iterations were required before the network can be maturely trained, in thisapplication the neural network identification had a convergence rate comparable to that of the RLS. Another advantage of the NSTC is due to the availability of neural network VLSI and the massive parallel architecture of the neural network there will be a computation advantage over conventional recursive algorithms. This will enable .real-time implementation with faster sampling rate for system with wide bandwidth. Also another advantage of the NSTC is that because the identification is done by the neural network, it inherits the decentralize property, meaning if there is a failure in a node or connection the impact on the performance will be minimal. Whereas with the conventional digital filter a failure in one of the coefficient will have a major impact on the output. With all the above encouraging characteristics there is one disadvantage of using the neural network and that is the lack of understanding how the dimension and activation characteristics of a network is related to its accuracy and stability. These issues of the recursive algorithms have been addressed and elaborately analysed in (Kumar, 1990). 45

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. 5.1 Future research The NSTC can be modified and extended to control systems that are not only non-minimum phase but also nonlinear. This is so that the properties of neural networks can be fully exploited. A system that have the above characteristics is a two degree of freedom robotic manipulator with the second link being flexible. Most conventional adaptive control schemes rely heavily on the inverse dynamics and therefore showed great limitations with this type of system (Centinkunt and Yu, 1990). 46

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BIBLIOGRAPHY Astrom, K. and Wittenmark, B., "On self-tuning regulators", Automatica, 9, pp.185-199, 1973. Antsaklis, P., "Neural networks in control systems", IEEE Control Systems Magazine, April 1990. Bavarian, B. "Introduction to neural networks for intlligent control", IEEE Control Systems Magazine, April 1988. Centinkunt, S., and Book, W., "Performance Limitations of Joint Variable Feedback Controllers due to Structural Flexibility", IEEE Transaction on Robotics and Automation, Vol. 6, No. 13, 1990. Clark, D., and Gawthrop, P., "Self-tuning controller", in proceedings lEE, 126, pp.633-640, 1979. Franklin, F.G., and Powell, J.D., Digital Control of Dynamic Systems, Addison Wesley, Reading, Mass. 1981. Fraser, A., and Daniel, R., Perturbation Techniques for Flexible Manipulators, Kluwer Academic Publishers, Norwell, Massachusetts, 1991. Hetch:.Nielsen, R. "Theory of the backpropogation neural network" in proceedings of the International Joint Conference on Neural Networks, Washington D.C., 1989 Ho, T., Ho, H. "Stochastic state space neural adaptive control", in proceedings the Third International Conference on Advances in Communication and Control Systems, Victoria, B.C., Canada, Oct. 16-18, 1991a. Ho, H., Ho, T., Wall, E., and Bialasiewicz, J., "Stochastic neural self-tuning adaptive control", in proceedings of the Third International Conference on Advances in Communication and Control Systems, Victoria, B.C., Canada, Oct. 16-18, 1991b. Ho, T., Ho, H., Wall, E., and Bialasiewicz, J., "Stochastic Neural Direct Adaptive Control", in proceedings of the 1991 IEEE International Symposium on Intelligent Control, Arlington, Virginia, Aug. 13-15, 1991c. Ho, T., Ho, H., and Bialasiewicz, J. "Stochastic neural adaptive control for nonlinear time varying systems", in proceedings of the 1991 International Conference on Artificial Neural Networks in Engineering, St. Louis, Missouri, Nov. 10-12, 1991d. Ho, T., Ho, H., and Bialasiewicz, J. "On stochastic newton adaptive control", in proceedings of the lASTED International Symposium on Adaptive Control and Signal Processing, New York, Oct. 10-12, 1990. 47

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Hunt K., Sbarbaro, D., Zbikkowski, R., and Gawthrop, P., "Neural Networks for Control SystemA survey", Automatica, Vo. 28, No.6, 1992. Kawato, M., Setoyama, T. and Suzuki, R. "Feedback-error-learning of movement by multi-layer neural network", in proceedings of the International Neural Networks Society First Annual Meeting; 1988. Kumar, P., "Convergence of Adaptive Control SchemesUsing Least-Squares Parameter Estimates", IEEE Transactions on Automatic Control, Vol. 35, NO 4, pp. 416-424, April1990. Levin. A., and Narendra, K.; "Control of Nonlinear SystemsUsing Neural Networks: Controllability andStablilization", IEEE Transactions on Neural Networks, Vol4. NO.2, March 1993. Miller, T., Sutton, R., and Werbos, P., Neural Networks for Control, The MIT press, Cambridge, Massachusetts, 1990. Miyamoto, H., Kawato, M., Setoyama, T. and Suzuki, R. "Feedback-error learning neural network for trajectory control of. a robotic manipulator", Neural Networks 1:251.,.265, 1988. Narendra, K., and Parthasarathy, K., "Identifciation and control of dynamical systems using neural networks" IEEE Transactions on Neural Networks, Vol 1. NO. 1, March 1990. Proano, J., Neurodynamic Adaptive Control .Systems, Ph.D Dissertation, University of Colorado, Boulder, 1989. Psaltis, D., Sideris, A., and Yamamura, A., "A multilayered neural network controller" IEEE Control Systems Magazine, April 1988. Rumelhart, D., and McClelland, J., Parallel Distributed Processing: Vol 1, Foundations, The MIT Press, 1987. Spong, N. M., and Ortega, R. (1988), "Adaptive Motion Control of Rigid Robots: A tutorial" in Proceedings of the 27th IEEE conf. on Decision and Control, pp. 1575-1584, Dec. 1988. Yamada, T., and Yabuta, T., "Neural Network Controller Using Autotuning Method for Nonlinear Functions", IEEE Transactions on Neural Networks, Vo 3, No. 4, July 1992. 48

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APPENDIX Simulation Program The simulation was perforemed using the software MATLAB. The program shown below is the NSTC scheme. clc clear. % % BEGIN ---------------------------------------------------------------------------------------------%NUMBER OF iTERATIONS SIMULATION N3=1500; ndisp=30; ALGsr= 1; ALGri = 1; ALGij = 1; ID=1; % 1==> Gradient 2==> Newton .3=>MV % 1==> Gradient 2==> Newton 3==>MV % 1=> Gradient 2==> Newton 3=>MV % 1=> RLS 2==> Neural J.D. O==>Determistic % ----------------------------------------------------------------------------------------------------------------------% % ===== INITIALIZATION ==================================== %PLEASE SELECT THE DIMENSION OF THE STATE VECTOR XO, %INPUT VECTOR UO, OUTPUT VECTOR YO, AND PARAMETER VECTOR %PO BY MODIFYING THE FOLLOWING STATEMENTS: % % P0=4; POO= 1; PSIO= 1; % ----------------------------------------------------------------------------------------------------------------------% %Plant [a1 a2 a3.:.ana bO b1 b2 ... bnb]; % A= [.7 .5 -.3]'; B=[1 .2 -.1 .3]'; % A = [.7 .5]'; B=[1 .2 -.1]'; % THETAp = [.7 .5 1 .2 -.1]'; %minimum phase 2nd order plant % A= [.7 .5-3]'; B = [1 .2 -.1 3]'; % THETAp = [.7 .5 -.3 1 .2 -.1 .3]'; %minimum phase 3rd order % THETAp = [.7 .5 -.3 1 .2 -.1 3]';% non-minimum phase 3rd; ld=4-10 % A=[.7 .5 -.3]'; B=[l .2 -.1 3]'; % THETAp = [-2.58 2.18 -.5965 -429.7 884.8 -430.8]'; %missile nmp % THETAp = [-3,987 5.96 -3.96 .987 -6.94e-5 6.92e-5 6.9e-5 -6.88e-5]'; % Mxl %THETAp = [-3.87 5.63 -3.64 .882 -.0068 .0066 .0065 -.0063]'; %missile %THETAp = [-2.979 2.96-.979-.0047 .0094 -.0047]'; %Submarine load plant num=numd'/dend(l ); den=dend'/dend( 1); 49

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B=num; A=den(2:length( den)); % B=numd A=dend(2,:) THET Ap = [A' B']'; na=length(A);nb=length(B)-I ;d=l; nf=d-I; ne=nf+nb; ng=na-I; nc=O; %This assumes the noise has no dynamics, Le. C= I; PO= (ng+1)+(ne+1)+nc; %Dimension of THETA POp=na+nb+ I; %Dimension of plant's THETA THETAEST=I *ones(P0,1); %load thetaest THETAO=THET AEST; yest=O; w=O; P=POO*eye(PO,PO); PSip=PSIO*ones(POp, 1 ); PSid = zeros(PO,I); K= I.S *ones(PO, 1); Y1=zeros(ng+ I,I); UI=zeros(ne+ 1,1); Yc=zeros(ng+l,l); Uc=zeros(ile,l); Yl p=zeros(na, 1 ); U lp=zeros(nb+ 1, I); Ud=zeros(d,l); Yd=zeros(d,I); %delayed values ofu, y and w W d=zeros( d, 1); y=O; u=O; VARV=O; :MEANV=O; % output y(k), input u(k) % Output noise variance n0=2; ni = 5; n2=15; n3::::Po; %Dimensions of Neural Network NETr = zeros(n1,1); NETi = zeros(n2,1); NETj = zeros(n3,I); Is= zeros(nO,l);. Or= zeros(n1,1); Oi = zeros(n2,1); Oj = zeros(n3,1); ALPHAj = .03*ones(n3,1);, ALPHAi = .03*ones(n2,1); ALPHAr = .03*ones(nl,l); Hj = O*ones(n3,1);, Hi= O*ones(n2,I);, Hr = O*ones(n1,1); Kj = 3*ones(n3,1);, Ki = 2*ones(n2,1);, Kr = 2*ones(nl,I); Wsr = rand(nO,nl); wri = raitd(nl,n2); Wij = rand(n2,n3); mu::.8; lambda0=.99; lambdak = .995; LAMBDA =I; Pij = 10*ones(n2,n3); Pfi = 5*ones(nl,n2); Psr = 5.3*ones(n0,nl); 50

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Rn = .001; Re=.9; % % ===== END OF INITIALIZATION ============================ rand(' seed', 10); % --------------------------%:::::BEGIN ITERATION::::: fork=l:N3 % ===== STOCHASTIC ARMA REPRESENTATION OF A LINEAR PLANT ----------------% % y(k)+a1y(k-1)+ ... +anay(k-na)=bOu(k-d)+b I u(k-1-d)+ ... +bnbu(k-nb-d)+v(k) % y(k)=PSip'(k)*THET Ap(k)+v(k) % PSip'=[ -y(k-1 ) ... -y(k-na) u(k-d) ... u(k-nb-d)] % THETAp(k)'=[a1 a2 ... ana bO b1 b2 ... bnb] % THETA'(k) =[gO g1 ... gng eO el...ene] % PSid'(k) = [y(k-d) .. y(k-d-ng) u(k-d) .. % yest(k) = PSid(k)'*THET AEST %=======Computmg THETA ======::;:===== if d==1 E=B; G=-A; %g(i)=-a(i+1), i=O .. ng G=q-1(1-A) end THETA = [G'E']'; %PARAMETRIZATION FOR PSI(k). % % ---------------------------------------------------------------------------------------------------------------------% % u=u(k-1) y=y(k-1). for i=d-1:-1:1 Ud(i+1)=Ud(i);, end, Ud(1)=u; %[u(k-1) ... u(k-d)] for i=d-1:-1:1 Yd(i+l)=Yd(i);, end, Yd(l)=y; %[y(k-l) ... y(k-d)] for i=d-1:-1:1 Wd(i+l)=Wd(i);, end, Wd(1)=w; %[w(k-1) ... w(k-d)] %==== PSip(k) = [-y(k-1) .. -y(k-na) u(k-d) .. li(k-d-nb)]' for i=na-1:-1:1 Ylp(i+1)=Y1p(i);, end; Ylp(l)=-Yd(l); for i=nb:-1:1 Ulp(i+1)=U1p(i);, end; Ulp(l)=Ud(d); PSip = [Ylp' U1p']'; %====PSid(k) = [y(k-d) .. y(k-d-ng) u(k-d) .. u(k-d-ne)] for i=ng:-1:1 Y1(i+l)=Yl(i);, end; Yl(l)=Yd(d); %[y(k-d) .. y(k-d-ng)] for i=ne:-1:1 U1(i+l)=Ul(i);, end; U1(1)=Ud(d); %[u(k-d) .. u(k-d-ne)] PSid = [Yl I U1 ']'; % PSI(k-d) 51

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% =========================================================== % ----GENERATING NOISE v(k) ---rand(' normal') v=sqrt(VARV)*rand(l,l)+!\ffiANV; % % ----COMPUTING y(k) & w(k) ----% y=PSip'*THET Ap+v; %y(k) tau=.5; w=tau*w + (1-tau)*2; %*sign(sin(0.004*(k))); %command signal w(k) w=(w/2)+1; % % ----END OF PLANT -------------% ----------------------------------------------------------------------------------------------------------------------%-----ADAPTIVE ESTIMATION----% ===== THE STOCHASTIC LEAST SQUARES ALGORITHM (SLA) -------------------% % =========================================================== % ----BEGIN ESTIMATION ----% THETAEST =[gO gl ... gng eO el ... ene]' yest=PSid'*THET AEST; % PREDICTED OUTPUT yest(k) e=y-yest; % PREDICTION ERROR e(k) ifiD=l K=P*PSid*inv(l+(PSid'*P*PSid)); %OPTIMAL GAIN THETAEST=THETAEST+K*e; %PARAMETER ESTIMATION P=(P-K*PSid'*P); end %==========Neural identification ======== ifiD=2 ls(l)=l; Netr = Wsr'*ls; tempr = (ALPHAr/2). *(Netr+Hr); Or= Kr. *tanh(tempr); Or(l)=l; Neti = Wri'*Or; tempi = (ALPHAi/2). *(Neti+Hi); Oi = Ki.*tanh(tempi); Oi(l)=l; Netj = Wij'*Oi; 52

PAGE 53

tempj = (ALPHAj/2). *(Netj+Hj); Oj = Kj. *tanh(tempj); THET AEST = Oj; if k== 1 save thetaest THET AEST, end PSI=PSid; tempj2 = cosh(tempj). *cosh(tempj); tempi2 =cosh( tempi). *cosh( tempi); tempr2 = cosh(tempr). *cosh(tempr); Fdotj = (Kj. ALPHAj/2)./(tempj2); Fdoti = (Ki. ALPHAi/2)./(tempi2); Fdotr = (Kr. ALPHAr/2)./(tempr2); dj = Fdotj. *PSI; PSiij = Oi*dj'; di = (Wij*dj). *Fdoti; PSiri = Ot*di'; Q = Fdoti .* (Wij*(Fdotj.*PSI)); dr = Fdotr .* (Wri*Q); PSisr = Is*dr'; if ALGij == 1 % Gradient Lij = mu*PSiij/LAMBDA; end if ALGij == 2 %Newton Sij = (PSiij. *PSiij;*Pij) + (lambdak*LAMBDA *ones(n2,n3)); Lij = (Pij.*PSiij)./Sij; . . Pij = (Pij(Lij.*Sij.*Lij))/hunbdak; end if ALGij = 3 % Minimum Sij = (PSiij.*PSiij.*Pij) + Re*ones(n2,n3); Lij = (Pij.*PSiij)./Sij; Pij = Pij (Lij. *PSiij. *Pij) + Rn*ones(n2,n3); end if ALGri == 1 % Gradient Lri = mu*PSiri/LAMBDA; end if ALGri == 2 % Newton Sri= (PSiri.*PSiri.*Pri) + (lambdak*LAMBDA*ones(nl,n2)); Lri = (Pri. *PSiri)./Sri; Pri = (Pri (Lri. *Sri. *Lri) )llambdak; end if ALGri == 3 % Minimum Variance Sri= (PSiri.*PSiri.*Pri) + Re*ones(ri1,n2); Lri = (Pri. *PSiri)./Sri; Pri = Pri-(Lri.*PSiri.*Pri) + Rn*ones(n1,n2); end if ALGsr == 1 % Gradient Lsr = mu*PSisr/LAMBDA; end if ALGsr == 2 % Newton 53

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Ssr = (PSisr.*PSisr.*Psr) + (lambdak*LAMBDA*ones(n0,n1)); Lsr = (Psr. *PSisr)./Ssr; Psr = (Psr(Lsr.*Ssr.*Lsr))/lambdak; end if ALGsr = 3 % Minimum Vasrance Ssr = (PSisr. *PSisr. *Psr) + Re*ones(n0,n1); Lsr = (Psr. *PSisr)./Ssr; Psr = Psr-(Lsr.*PSisr.*Psr) + Rn*ones(nO,n1); end Wij = Wij + Lij*e; Wri = Wri + Lri*e; Wsr = Wsr + Lsr*e; %LAMBDA= LAMBDA +(e*e'-LAMBDA)Ik:; lambdak = lambdaO*lambdak+( 1-lambdaO); Re = Re + (e*e'-Re)lk:; for i=n0:-1:2 Is(i)=Is(i-1);, end end % % ----END OF ESTIMATION ----% % ==== MINIMUM VARIANCE ADAPTIVE CONTROL ----------------------------------------------------% % % ------------------------------------------------------------------------------------------------------------------------------------% ----BEGIN ADAPTIVE CONTROL----for i=ng:-1: 1 Yc(i+1)=Yc(i);, end; Yc(l)=y; %[y(k) .. y(k-ng)] for i=ne-1:-1:1 Uc(i+l)=Uc(i);, end; Uc(1)=u; %[u(k-l) .. u(k-ne)] ld = .1; ld2= .06; ld3=0; if ID=O THET AEST=THETA;, end % Q = ld + q-lld2 if k<1 THETAc=THETA;, else THETAc=THET AEST;, end Gest(l:ng+l,l) = THETAc(1:ng+1); % G Eqest(l:ne+1,1) = THETAc(ng+2:ng+2+ne); % E Eqest(1) = Eqest(1)+ld; % E+Q Eqest(2) = Eqest(2)+ld2; %Eqest(3) = Eqest(2)+ld3; % u(k) = {w(k)-[gOy(k)+ ... +gncy(k-ng)] -[elu(k-l)+ ... +eneu(k-ne)] }leO SUMl = Eqest(2:ne+l)'*Uc; SUM2 = Gest'*Y c; 54

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%roots(Eqest) %break u=(w-SUM2-SUM1)/Eqest(1); %u(k) %u=w; % -----END OF ADAPTIVE CONTROL---% =========================================================== -------------% % ----SIMULATION ERRORS ----------% ----SAVE THET A(k) & THET AEST(k) ---for j=1:PO THETA1 (k,j)=THETA(j); THETA1EST(kj)=THET AEST(j); end % ----SAVE y(k) & yest(k) ---Y(k,1)=y; YEST(k, 1 )=yest; % ----SAVE K(k) ---for j=1:PO K1(k,j)=K(j); end %-----SAVE U(k) ---U(k)=u; W(k)=Wd(d); % ---------------------------------------------------------------------------------------------------------------------% % -----THE PARAMETER IDENTIFICATION MSE(k) ---THETAER=TIIETAlTHETA lEST; forj=l:PO if k== 1, TMSE(k,j)=THET AER(k,j)"2; else TMSE(k,j)=TMSE(k-1,j)+(THETAER(k,j)"2-TMSE(k-1,j))/k; end end % -----THE OUTPUT PREDICTION MSE(k) ---YER(k)=y-yest; ifk=1, YMSE(k)=YER(k)"2; else YMSE(k)= YMSE(k-1 )+(YER(k)"2YMSE(k-1 ))/k; end %-----THE COST FUNCTION(k) J(k)---YERc(k)=y-Wd(d); if k=1, J(k)=YERc(k)"2; else J (k)=J (k -1 )+(YERc(k)"2-J (k -1) )/k; end % ===== DISPLAY MATRIX ===.:...-======================== % TIDS M-FILE IS USED TO MONITOR SYSTEM PERFORMANCES DURING 55

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%SIMULATION. % ========================================================= %-----TRANSFER DATA TO MATRIX DISMAT1---. DISMAT1{1,1)=k; DIS MAT 1 ( 1 ,2)=TMSE(k, 1 ); DISMAT1(1,3)=TMSE(k,2); DISMATl ( 1,4 )=TMSE(k,3); % DISMAT1(1,5)=TMSE(k,4); DISMAT1(1,6)=YMSE(k); DISMAT1 (1 ,7)=U(k); % -----TRANSFER DATA TO MATRIX DISMAT2 ---DISMAT2(1,l)=k; DISMAT2( 1 ,2)=J(k); DISMAT2(1,3)=Wd(d); DISMAT2(1,4)=y; DISMAT2( 1 ,5)=yest; % -----DISPLAY DISMATl & DISMAT2 ----if rem(k,ndisp )==0 home disp(' k TMSE1 TMSE2 TMSE3 TMSE4 YMSE U(k)') disp(DISMAT1) disp(' k J(k) w(k-d) y(k) yest'). disp(DISMA T2) %[fHETA THET AEST] end % % ----------END OF -------------------------------------------------------------------------------------------------%keyboard end %END OF FOR LOOP(k) %:::::END OF ITERATION::::: .. % % ----SYSTEMS GRAPHICS ----------SYGRAF % ----------------------------------DIS MAT % END OF SIMULATION --------------------------------------------------------------------------------------56



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REACTIONS OF SUBSTITUTED BIBENZYLS AND a'-HYDROXYBIBENZYLS WITH SUPERCRITICAL WATER UNDER COAL LIQUIFACTION CONDITIONS by Akiko Horiuchi B.A., International Christian University, 1969 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Master of Science 1988

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This thesis for the Master of Science degree by Akiko Kusuoka Horiuchi has been approved for the Department .of Chemistry by Anderson Date .:L-(, I ?d'JY

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Horiuchi, Akiko (M.S., Chemistry) Reactions of Substituted Bibenzyls and a'Hydoxybibenzyls with Supercritical Water under Liquifaction Conditions iii Thesis directed by Assistant Professor Michael A. Mikita Supercritical fluids have attracted special interest due to their unique physical properties which do not exist under common laboratory conditions. Recently, supercritical water has been studied as a coal liquifaction medium due to the relatively high coal conversions exhibited in supercritical water and its economic advantages. The object of this thesis was to examine the role of water under coal liquifaction conditions using substituted bibenzyls as the coal models. To accomplish this goal, series of substituted bibenzyls and a'-hydroxybibenzyls were synthesized via Wittig reaction with subsequent hydrogenation. The substituents synthesized were p-NH2 p-t-Bu, p-CH3 H, m-CF3 and p-CH3o2c. Both sets of compounds were reacted in a multi reactor system containing water under 4290 psi (0.30 kbar) at 400C for 3 hours corresponding to a supercritical water density of 0.095 g/mL. In many instances deuterium oxide was substituted for water. The

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iv dichloromethane soluble extracts from these reactions were analyzed via gas chromatography-mass spectrometry. Thermolysis pathways dominated the observed products from the substituted bibenzyls. Both the thermolysis products and recovered starting materials were observed to undergo deuter.ium exchange. The observation of exchange implies previously unknown reaction pathways water and bibenzyls under liquifaction The mechanisms for these reactions were not rigorously established, although electon donating substituents favored substitution suggesting an ionic pathway. In the case of p-carboxylic acid methyl ester bibenzyl, demethylation and decarboxylation predominated with a deuterium substitution pattern suggestive of an ionic pathway. Comparison of the product distributions in H 2o and o2o for the a'-hydroxy substituted bibenzyls suggests a primary isotope effect. This is an intriguing observation considering that the thermolysis pathway predominated. The a'-hydroxybibenzyls exhibited more extensive deuterium exchange than the simple bibenzyls, presumably due to the enhanced H(D)-atom transfer ability of the phenolic-H(D). The tautomerization pathway contributed

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v significantly to the product distribution with the a' hydroxybibenzyls. They also exhibited a primary isotope effect suggesting that the tautomerization is rate limiting. 2-Ethyl-4-substituted biphenyl ethers were also observed in some cases, presumably through the rear rangement of certain substitued a'-hydroxybibenzyls. Cyclization of p-NH2 p-CH3 and H a'-hydroxy substituted bibenzyls to dibenzodihydrooxepane was also observed.

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Like all other arts, the of Deduction and Analysis is one which can only be acquired by long and patient study, nor is life long enough to allow any mortal to attain the highest possible perfection in it. Sherlock Holmes, in "A Study in Scarlet"

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To Katsura, Shu, Hokuto, and Tadashi.

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ACKNOWLEDGEMENTS I would like to express my greatful thanks to my mentor Dr. Michael A. Mikita, for his instructions, encouragements, and ever lasting zest for chemistry. To Seifu Tadesse, Joel Boymel, Bonnie O'Connell, Roger Simon, for teaching around the lab and keeping the spirits up. To Dr. Robert Meglen and Dr. Larry Anderson for careful reading of the draft and helpful suggestions. To Tadashi without whom my entire research would have being impossible. I also like to express my gratitude to Prof. Paul Fenessey and Mr. Alan Quick, of Univ. of Colorado Health Science Center for MS analysis. To Dr. Bradley Brockrath of US Dept. of Energy, Pittburgh Energy Tech nology Center, for encouragement and support. and to Mr. Henry Davis for running the multireactor system. To Oak Ridge Associated Universities for their financial assistance in travel to Pittburgh by MAM. Finally, financial support by US Dept. of Energy (DE-FG22-85PC81544) is also greatly acknowledged.

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CONTENTS CHAPTER I. INTRODUCTION ...... 1-1 Object of the Study .... 10 II. SYNTHESIS OF SUBSTITUTED BIBENZYLS 12 2-1 Selection of Wittig Reagent 19 2-2 Protection of Hydroxy Group . 20 2-2-1 Acetyi ether .. 21 2-2-2 2-Tetrahydropyranyl ether . 21 2-2-3 Benzyl ether 22 2-3 Attempts to Synthesi e p-Bromobibenzyl ... 22 2-4 Attempts to Synthesi e p-Nitrobibenzyl 23 2-4-1 Reduction of p-nitrostilbene via hydroboration... 23. 2-4-2 Reduction of p-nitrostilbene via diamide .............................. 23 2-4-3 Hydrogenation of p-nitrostilbene using rhodium as a catalyst 26 2-4-4 Oxidation of p-aminobibenzyl with peroxytrifluoroacetic acid 26 2-4-5 Grignard reaction with copper iodide catalyst. 27

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X III. RESULTS AND DISCUSSION 28 3-1 Substituted Bibenzyls where R H 32 3-2 Substituted Bibenzyls where R OH 42 3-'3 Future P 1 ans ..... 49 3-4 Conclusions 49 IV. EXPERIMENTAL. 52 4-1 Synthesis . 53 4-1-1 a-Bromo-p-toluic acid methyl ester 53 4-.1-2 Salicylaldehyde benzyl ether 53 4-1-3 Salicylaldehyde acetyl ether 54 4-1-4 Salicylaldehyde tetrahydropyranyl ether. . . . . . . . . . . . . . 5l.J 4-1-5 Pyridinium-p-toluenesulfonate 55 4_-1-6 Diethyl-p-methylbenzylphosphate 55 4-1-7 4-Methylstilbene 56 4-1.-8 4-Methylbipenzyl 56 4-1-9 p-Bromobibenzyl ....................... 57 4-1-10 p-Nitrobibenzyl 57 A) By hydroboration reduction 57 B) By diimide reduction 58 C) By nydrogenation with rhodium catalyst 58 D) By oxidation with peroxide 59 E) By cuperous iodide coupling 59

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xi 4-2 Reactions .... 60 REFERENCES 64 APPENDIX ..................... 68

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xii TABLES TABLE 1. Product Analysis of Thermolysis of Bibenzyl by Various Researchers . 9 2. Compounds used in the Reaction .. 15 3. Preparation of Phos phonates 16 4. Preparation of Substituted Stilbenes . 17 5. Preparation of Substituted Bibenzyls 18 6. Reaction of p-Nitrostilbene with Borane Complex 24 7. Reaction of p-Nitrostiblene with p-Toluene-sulfonhydrazide 25 8. Hammett of Groups Used in the Reaction................................... 31 9. Product Distributions of Major Products 34 10. Summaries of the Reactions . 63

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FIGURES FIGURE 1. Ionization constant of water in high-temperature fluids of various densities .................................. 3 2a. Hydrocarbon solubility (w%) in water .. 3 2b. Inorganic solubility (w%) in water 3 Xiii

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CHAPTER I INTRODUCTION The ability of supercritical fluids (SCF) to dissolve inorganic salts was first reported by Hannay and Hogan at a meeting of the Royal Society of London in 1879. 1 It was only during this past decade, however, that the principles and practice of supercritical fluids have experienced rapid advances. Supercritical fluids have been applied to areas such as polymer and monomer processing, natural product and pharmaceutical process-ing, treatment of waste and coal liquifaction. Motivation for the development of supercritical fluid technology is a result of the high costs for energy-intensive separation techniques such as distillation. Increased environmental awareness has also intensified the search for non-toxic fluids to refrain traditional industrial solvents, such as chlorinated hydrocarbons. Increased demand for process techniques which tradi-2 tional methods cannot meet and increased interest in reactions under high temperature and/or pressure from a pure chemistry point of view have together hastened research with SCF.

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2 The possible use of supercritical fluids in coal liquifaction has recently attracted significant inter-est. The typical solvent for coal liquifaction is an organic solvent which can act as hydrogen donor, such as tetralin. These donor solvents are commonly hydrogena-tion products of coal liquifaction and thus refered to as process derived solvents. The disadvantages with the use of these solvents are high cost of their separation from other products, and the necessity of subsequent hydrogenation to make more efficient hydrogen donating species. Some donor solvents also become fixed. in the insoluble residue following liquifaction. Among common solvents, water has attracted special interest because of its low cost and relatively high coal conversion rate.3 Water has a critical temperature of and critical pressure of 217.7 atm. Above this critical temperature, a liquid phase does not exist regardless of the pressure. Consequently, supercritical water can be more liquid-like or more gas-like depending on density. Thus water above its critical temperature is most commonly referred to as a fluid. The ionization constants of water in high temperature fluids of various densities 4 is expressed in Fig. 1 For example, when density is doubled at 400C the ionization constant increases by

PAGE 16

3 -8 -9 , c:: Density= 0.7 IG -10 , "' c:: 0.6 , 0 , u -11 c:: 0.5 0 , .... , \ IG N -12 "( o.'4 .... c:: , 0 ,, ,,. .... , \4-13 ,,, 0 0.3 0'1 I 0 ...J -14 I o' 0 200 400 600 Temperature, oc Fig. 1. Ionization constant of water in high-temperature fluids of various densities. The solid line is the experimentally determined curve for liquid water under its own vapor pressure. The estimated extrapolation of the curve to the critical point is shown as a dashed line. The other dashed lines shown calculated values of the constant for single-phase fluid water under sufficient pressure to maintain the indicated densities. 3: 50 J ....... -300 400 Fig. 2a. Hydrocarbon solubility (wt %) in water :lOOt 3: 50 ...__...._1 __ ,.__ 300 400 Fig. 2b. Inorganic solubility (wt %) in water

PAGE 17

about three powers of ten. Temperature and pressure dependence of dielectric constant allow convenient control of solvent properties over a large range. The ionization constant of liquid water increases with temperature, then drops rapidly just prior to the criti-cal temperature. As the result, the solubility of hydrocarbons in water increases dramatically as it reaches supercritical temperature(Fig. 2a, Fig. 2b).ij Wender, et al.,(198ij) have shown that when coal is treated with supercritcal water alone, the amount of THF extractable products depends upon the water density. 5 Barton (1983) has indicated that, in coal liquifaction, water is a good extraction solvent as well as good transportation medium. 6 Stenberg and co-workers (198ij) studied supercritical water in presence of hydrogen sulfide. Under their conditions, water acted only as slurry liquid and did not participate in reactions.ij In addition to the physical roles, water may participate as a reactant. In combination with carbon monoxide and hydroxide as catalyst, Ross and co-workers found that water first reacts with carbon monoxide to form formate which in turn reacts as a reducing reagent. In this case, water is a hydrogen source.7 8 In contrast to the carbon monoxide -water system, in the hydrogen sulfide -water system studied by Stenberg, hydrogen

PAGE 18

5 sulfide acted as hydrogen donor while water did not 4 react. In the thermolytic reaction of bibenzyl ether in water, Paulaitis, et al.,(1983) have shown that bibenzyl ether decomposed at 400C by both pyrolytic and hydrolytic pathways, later leading to the formation of benzyl alcohol, indicating direct participation by water.9 Recent experiments in this laboratory did not exhibit an isotope effect when coal was liquified with H 2o or c2o along with tetralin and hydrogen. These suggest that under the experimental conditions, water was not a rate limiting reactant. Similar experi-ments in the absence of molecular hydrogen suggest that molecular hydrogen plays dominant role regardless of mechanism.10 Our group also has shown that when 4benzyl phenol was reacted with c2o, recovered 4-benzyl phenol contained at least two deuteriums. One explanation for this observation may be electrophilic aromatic substitution of deuterium.11 The reaction of hydroquinone monobenzylether in c2o resulted in the formation of triply-deuterated catechol monobenzyl ether. While the formation mechanism is still uncertain, this is another indication of possible ionic pathways in the reaction of 12 supercritical water.

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6 Based upon this overview, it appears that super-critical water sometimes plays a physical role, and sometimes acts as an active participant. If the water is a reactant, how does it react? If it behaves as a sol-vent, does it assist reactions? These are some of the many questions that still need to be answered regarding coal liquifaction in a super critical water system. The behavior of bibenzyl at high temperature has been studied intensively by previous researchers. In 1979, Virk proposed a concerted mechanism in which the intermediate (VI) takes hydrogen from dihydronaphthalenei followed by the cleavage of phenyl-phenyl bond. 13 (VI ) This mechanism was immediately rejected by others. Stein and Miller (1979) calculated the rate of reaction based on the proposed mechanism and pointed out that the observed k=105sec-1 was too slow for the calculated value of k=10-12 6 sec-1 14 Vernon (1979) also indicated that thermolysis of bibenzyl is not accelerated by the presence of tetralin, a good hydrogen donor, indicating 15 no proton transfer. Stein's and Vernon's results

PAGE 20

7 supported a radical mechanism where radical cleavage of ethane bond is proposed to be the rate determining 16-19 step. The thermolysis radical cleavage mechanism of bibenzyl is illustrated in Scheme 1. Scheme 1 L @CH3 + @-CH=ca-@ Extensive kinetic studies of pyrolysis of biben-zyl in liquid phase at 300C-425C was done by Miller and Stein (1981).20 The results where all in agreement with a radical mechanism were the production of toluene is first order in bibenzyl. Livingston, Zeldes and Conradi (1979) observed 1,2-diphenylethyl radical by ESR

PAGE 21

8 when bibenzyl was heated to 460C-560C. In the presence of excess toluene, benzyl radical was observed at 560C.21 Ross and Blessing (1980) calculated half life-times of bibenzyl at 400C and 335C, and found t 112 to be 2.0 hrs and 160 hrs respectively,22 based on log k -1 23 (sec ) = 14.4-57/2.303RT. They concluded that under the standard reaction time of 30 min, thermal scission can not play a significant role at these temperatures. They also noted that coal conversion rate is not directly related to the hydrogen donating ability of the solvent, raising a question on the previously accepted mechanism of simple thermal cleavage followed by capping with proton. Vernon (1980) studied hydr6cracking of bibenzyl at 450C, 30 min, in the presence of tetralin, tetralin and molecular hydrogen, and molecular hydrogen alone. Conversion rate increased when molecular hydrogen was added to the tetralin. Also, conversion rate increased as hydrogen pressure increased. This indicated direct 24 participation of molecular hydrogen. The product analysis of the thermolysis of bibenzyl at various temperatures, pressures and reaction times, has been studied by Poutsma (1980).25 The products of reactions, done by various researchers has

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Table 1 Product Analysis of Thermolysis of Bibenzyl by Various Researchers Product distribution (carbon Researchers Tamp. Time p Conv.l Conditions 12lCH3 .0CH=CHm tli2CHCH3 (JZ1CH2CHtll )2 (JZICH2)2CHIZJ IZICH2CH3 Phenonthrene tli2CH2 IZl Poulmt (1) 4o1"c 1' mill '4 Kf't 1.7 oOIT\busuon tubt 26.7 9.7 1.1 3,.2 26.7 -d d 0.6 401 20,., 52 ne lo,d1otlfon of ohakn1 ,4.7 32.6 0.6 0.6 ,_, ,,4 1.7 1.6 401 15 mill 1tqutd 1.4 30.0 10.6 11.2 44.6 3.3 d d 0.3 401 20,., 1tqutd 85.0 58.8 7.3 3.4 2.2 1.0 -2.4 18.3 t .0 ( 2 ) 400 2hr 1tqutd 71.2 2-11 rnrn 38.1 n.4 t:u 8.0 2.8 0.8 1.9 2.6 400 30 mtn Hqutd 4.9-6.0 lubo, no shakfn1 11.0.7 12.4 12.4 31.2 5.4 f.S 2.9 2.0 Yomon(l) "":J 30 mtn 1tqutd 69,1 1.!orn 11 20 om Mo 411.7 41.& . 0.3 1.0 s.o 1.2 1ood: o.s-t .o 1 otow agtlolten (mo10J) 11 (earbon no.)/14 (I) H.LPoulsmt, Fuo1 1980,59, US. (2) L.H.Vtr11011, Fuo1 1980, 58, 102. (3) R.E.Hm.r, s..stot., J. f'bol. c:Mtn. 198!, as, sao. \.0

PAGE 23

10 been summarized in Table 1. While toluene and stilbene were common products, the reactions of bibenzyl at high temperatures is temperature sensitive as well as reac-tion time sensitive. Kakemura, et al., (1981) found that bibenzyl in a carbon monoxide/water system with cobalt or molybdenum as a catalyst, forms di-and tri-methylated benzenes along with other minor products. Benzene and toluene were the major products.26 In the presence of metal catalysts the reactions seem to take completely different pathways. 1-1 Object of the Study At first glance, water would appear to be neither a good solvent nor a good reactant. for the commonly employed coal liquifaction model reactions. The object of this thesis was to study the behavior of supercritical water in presence of a series of coal models to examine whether water exhibits solvent properties or reaction chemistry under liquifaction conditions. Substituted bibenzyls were chosen as the coal model compounds for two basic reasons. First, bibenzyl is the most studied of the coal model compounds at high temperatures, consequently it provides the most

PAGE 24

11 established mechanistic pathways. Secondly, unlike benzyl ethers which when radically cleaved will exhibit some ionic character to the transition states, bibenzyls are not expected to exhibit significant ionic character. Consequently, ambiguity between radical reactions and ionic reactions will be minimized.

PAGE 25

CHAPTER II SYNTHESIS OF SUBSTITUTED BIBENZYLS All the bibenzyls used in the reaction with supercritical water were synthesized according to the reactions illustrated in Scheme 2 to 4. Phosphonates (Ia -Ig) were synthesized from substituted benzyl halides and triethylphosphite (Scheme 2). All substituted benzyl halides were commercially available except a-bromo-p-toluic acetate which was synthesized from the methylation of a-bromo-p-toluic acid with diazomethane.27 Scheme 2 Synthesis of Phosphonates R 1-CHi 2r. -CH2-(Q( X 0 v R1 = Br or Cl )( v ,. N02 H lb t-Bu H lc CH3 H ld H H ,. H CF3 ., f CH30CO H lg Br H

PAGE 26

1 3 The phosphonates were coupled with benzaldehyde or protected salicylaldehyde, via Wittig reaction to form the stilbenes (Scheme 3). Scheme 3 Synthesis of Stilbenes R2 X v )( v R2 )( 11411 N02 H H 111411 N02 II b t-Bu H H lllb t-Bu lie CH3 H H lllc CH3 II d H H H llld H II H CF3 H Ill H II f CH30CO H H lllf CH30CO llg Br H H lllg Br Salicylaldehyde was protected as the benzyl ether, according to the reaction illustrated below. (Qt COH OH (Q( COH OCH2@ Finally, the stilbenes were hydrogenated to v H H H H CF3 H H obtain the bibenzyls (IVa-IVf, Va-Vf), (Scheme 4). R2 0CH20 0CH20 0CH20 0CH20 0CH20 0CH20 0CH20

PAGE 27

14 Sheme 4 Synthesis of Bibenzyls H2 /Pd ) X v R3 X v R3 IVa NH2 H H Va NH2 H OH IVb t-Bu H H Vb t-Bu H OH IVc CH3 H H Vc CH3 H OH IVd H H H Vd H H OH IVe H CF3 H Ve H CF3 OH IVf CH30CO H H Vf CH30CO H OH All substituted groups were unaffected by hydrogenation, except benzyloxy, bromo and nitro groups. Benzyloxy and bromo groups were eliminated while the nitro group was reduced to the amino group. The physical properties of these substituted bibenzyls are complied in Table 2. The synthetic results are summarized in Table 3 -5. A more detailed discussion of each of these synthetic steps will now follow.

PAGE 28

R Table 2 Compounds Used in the Reaction v R X v Compound m .pt. e>ep/lit c m .wt. m/e [relative sensltfvity] H NH2 H IVa 42-44/48(1 ) 197 197(25, M+], 1 06( 100, M+] H t-Bu H IVb 37-38/ 238 238(25, 147[ 100, M+-PhCH2 ] H CH3 H IVc 25-26/24-26 (2 ) 196 196[25, M+], 105[100, M+-PhCHz) H H H IVd 48.5-49.5/52-52. 5 (3 ) 182 182(49, M+], 91[ I 00, M+ -PhCHz ] H H CF3 IVe lfquid 250 250(25, M+], 159[ 18, M+-PhCH2 ], 91[ 100, PhCH2J H CH30CO H IVf 28-29/ 240 240[25, M+], 149(20, M+-PhCH2 ], 91( 100, PhCHz) OH NH2 H Ve 138-144/ 213 213[ 14, M+], 1 06(1 00, 1-1'1 -HOPhCHz ] OH t-Bu H Vb 58-59.5/ 254 254[42, M+], 147[ 100, M+HOPhCH2 ) OH CH3 H Vc 54-55/ 212 21 2[42, M+], 1 07(1 00, M+Cli 3PhCHz ], 1 05[1 00, OH H H Vd 79-80/85 (4 ) 198 198[27, M+], 1 07(1 DO, M+-PhCHz pM+-HOPhCHz J OH H CF3 Ve 43-44.5 I 266 266[25, M+], 109[100, M+-cF3PhCH2 ] OH CH3oco H Vf 92-100/ 256 256(14, M+], 107(100, M+-cH30COPhCH2 ] ..... lJ1 (1) .J V Braun, H.Dutsch, O.Koscilski, Br.1913, 46,1511. (2) R.L.HinHan, K.L.Hamm, J.Am.Chm.Soe. 1959,81,3294. (3) Hrck lndx (4) P .Ruggli, A Staub, Hlv Chirn.Acta. 1931, 20, 31.

PAGE 29

Table 3 Preparation of Phosphonates R 1-CH2-
PAGE 30

Table 4 Preparation of Substituted Stilbenes R2 (Eto>2r, -cni-Cll = Cll -@ 0 v R2 v --mmole R2 mmole reoct prod gm/mmole % m.pt."c comp gm gm lime yield yield eKp/Jil oppeoronce 5.00 20.7 H 2.20 20.7 3 hrs 2.54/12.8 61.6 149-150/156 11 powder lb 3.68 22.5 H 2.3, 22.5 3 lib 2.12/6.3 28.4 ,5.5-,7/ w noodle lc 3.62 15.0 H 1.60 15.0 48 lie 2.08/10.7 71.5 117-118/110-2 11 plat I d 3.42 15.0 H 1.60 15.0 48 lid '2.30/12.8 85.2 122-123/124 w plat It 3.10 10.4 H 1.11 10.4 8 II 1.7917.2 69.4 58-S9 I w noodl If 1.72 6.0 H 0.64 6.0 3 11r 0.4Sll 31.0 ISO-lSI I wplat. I 9 5.06 16.0 H 1.70 16.0 2 119 3.60/13.9 86.8 136-137/139 w nePdlo 1.84 7.7 .0CH20 1.62 7.7 3 Ill I.Sa/4.78 62.S 102-103/101 11 nudle I b 2.84 10.0 .0CH20 2.12 10.0 a Ill b 1.51/4.42 44.0 68.S-6'/ w plate I c 3.24 13.4 .0c112o 2.84 13.4 8 lllc 1.98/S.OS 37.7 58-59/ v needle I d 4.00 17.5 .0CllzO 3.71 17.5 8 llld 2.60/9.0' 51.9 65-66 I 11 plat It 5.00 16., .0c11 2 o 3.S8 16.9 a Ill 4.39/12.4 73.3 II oil If 4.58 16.0 .0CH20 3.39 16.0 3 mr 1.00/2.9 I 8.1 11 oil 19 3.31 10.7 .0CH20 2.27 10.7 2 Ill 9 1.85/5.07 47.4 66.5-67.0/ w povdor

PAGE 31

Table 5 Preparation of Substituted Bibenzyls Reactants Solvent Pd React Product comp gm mmole type ml gm t1me comp gm mmole yield II a 2.70 12.0 EtOHITHF 100/100 0.20 2hrs IVa 2.35 11.9 99.4 lib 1.83 7.61 EtOH 200 0.10 2 IVb 1.80 7.55 99.3 lie 1.87 9.52 EtOH 200 0.10 2 IV c 1.62 8.31 87.3 lid 1.50 8.30 EtOH 200 0.10 2 IVd 1.39 7.64 92.0 II 2.41 9.71 EtOH 220 0.12 2 IV 2.40 9.66 99.4 llf 0.45 1.88 EtOHITHF 180/20 0.10 2 IVf 0.44 1.83 97.5 llg 1.45 5.59 EtOH 200 0.10 2 IV d 0.95 5.20 93.0 lila 2.46 7.43 EtOH/THF: 200/50 0.30 4 Va 1.50 7.14 94.7 lllb 1.27 3.70 EtOH 200 0.20 2 Vb 0.97 3.82 103 lllc 0.95 3.70 EtOH 200 0.20 2 Vc 0 .64 3.02 94.9 ,_. (X) llld 1.28 4.46 EtOH 200 0.30 2 Vd 0.97 4.91 110 Ill 4.39 12.4 EtOH 200 0.50 2 v. 3.60 13.5 109 lllf 1.00 2.90 EtOHITHF 150/50 0.30 3 Vf 0.98 2.82 97.3

PAGE 32

19 2-1 Selection of Wittig Reagent Two types of Wittig reagents 'were considered. Triphenylphosphite, which, after reaction with. benzyl halide followed by base, forms the phosphorus ylide that reacts as the nucleophile. The other was triethylphos-phite, which reacts with benzyl halide to form diethyl-phosphonic benzyl ether followed by treatment with base, generating phosphonate carbanion, another strong nucleophilic specie. After isolation of triphenylbenzylphosphonium bromide and diethylphenylphosphonate, both compounds 28 29 were reacted with benzaldehyde. Both produced stilbene but reaction with diethylphosphonate exhibited fewer side products, as identified by TLC. There are three other advantages to the use of diethylphenylphosphonate. The first is the nucleophilicity of the intermediates. Phosphonate car-banions are known to be more nucleophilic than analogous ylides.30 The second is the required reaction condi-tions. In the reaction of phosphonium bromide, n-butyl lithium, a pyrophoric and a highly moisture sensitive liquid, is used as a base. Consequently, extreme care must be taken in its handling, and the reaction must be done under a dry, inert atmosphere. On the other hand,

PAGE 33

20 the reaction with phosphonate requires only sodium hydride as a base. The latter reaction requires simply the use of a drying tube rather than the dry, inert atmosphere. The third advantage is the physical form of the synthetic intermediates. The phosphonates are usually liquids, whereas the phosphonium bromides are solids. Solids are often difficult to obtain from oil. As a result, phosphonate was selected as Wittig reagent. 2-2 Protection of Hydroxy Group In the syntheses of a'-hydroxybibenzyls, salicylaldehyde was used as a synthetic precursor. In these syntheses, the hydroxy group must be protected prior to Wittig reaction. The requirements for the selection of good hydroxyl protecting groups are: 1) they must react quantitatively with the hydroxyl group, 2) they should not interfere with the main reaction, 3) they must be eliminated easily to return the original hydroxyl group.

PAGE 34

21 2-2-1 Acetyl ether The acetyl group was first chosen as a protecting group since it is one of the most common protecting groups, with simple synthetic procedures, and can be eliminated readily under mild conditions. Salicylaldehyde acetate was synthesized, following the standard method.31 Salicylaldehyde acetate was reacted with diethylbenzylphosphonate. The IR spectrum of the dark yellow oil thus obtained revealed hydrogen bonded OH, indicating the loss of an acetyl group. Consequently, this method was abandoned. 2-2-2 2-Tetrahydropyranyl (THP) ether THP ether was selected next since, in our laboratory, protection of salicylic acid was success-fully accomplished by THP. Preparation of THP ether was carried out following Miyashita's method,32 in which pyridinium-p-toluenesulfonate (PTS)3334 is used as a catalyst. Most of the starting materials were still unreacted after 4 hrs, 24 hrs, and 48 hrs. Consequently, this method was also abandoned.

PAGE 35

22 2-2-3 Benzyl ether In a benzyl ether, the bulky phenyl group is separated by one methylene group which would be expected to reduce steric hinderance. Benzyl ether is particulary desirable since it can be eliminated by hydrogenation, simultaneous with the reduction of the double bond in the stilbene. The benzyl ester of salicylaldehyde was synthesized in relatively good yield (60 %) by Miyano's method.35 The subsequent Wittig reaction was also successful. The benzyl group was quantitatively eliminated during hydrogenation in the presence of excess palladium catalyst. Thus all a'-hydroxybibenzyls were synthesized using salicylaldehyde benzyl ester via a'benzoylstilbenes. 2-3 Attempts to Synthesize p-Bromobibenzyl Since hydrogenation of p-bromostilbene (Ilg) resulted in elimination of bromide, direct bromination of bibenzyl with bromine and a catalytic amount of iron, was attempted following Litz.36 Four experiments were done varying reaction time temperature and ratio of the starting materials. GC/MS analysis indicated seven major

PAGE 36

23 products, including p-bromobibenzyl, p-bromostilbene (IIg) and dibromo compounds. Since the.capillary column GC retention times were very close to each other, separation of the products was not attempted. 2-4 Attempts to Synthesize p-Nitrobibenzyl Hydrogenation of p-nitrostilbene (IIa) resulted in reduction of the nitro group to the amino group. Several attempts were made to synthesize and separate pnitrobibenzyl using alternative methods. 2-4-1 Reduction of p-nitrostilbene via hydroboration p-Nitrostilbene (IIa) was treated with borane-pyridine and borane-THF complexes, varying solvent, temperature, reaction time and ratio of the reactants,3738 as shown in Table 6. Run B resulted in the best p-nitrobibenzyl/(IIa) ratio (0.56). Separation was not attempted. 2-4-2 Reduction of p-nitrostilbene with diamide p-Nitrostilbene (IIa) was reacted with ptoluenesulfonhydrazide, a diamide precursor, following Dervey and Tamalen's method.39 Reaction conditions are

PAGE 37

Table 6 24 Reaction of of p-Nitrostilbene with Borane Complexes H3B:Py H3B:THF Run I Ia* B* A* Solvent Reaction Conditions NBB/IIa** to INke nF II + B : refluK 2 hr I over nfght NP Hidio + A : to make solution cfdil: 2 eKcess hetto 60C NP 3 lla + B : hr t room tl!mp NP followed by rtfulKing at 60 C 4 1/3 Mtsityltne II + 8 : 80 c I 30 min 0.032 + A : rtflUIC over night 5 Trig 'Iyme IIi + 8 : 21 0 c I 30min 0.36 +A: 21oc, 90mln 6 excess Trig 'Iyme II+B :21oc, 30mtn 0.37 +A: 210 c, 90 min 7 Trig 'Iyme lla : 130 c +a :21o c, detect. 30 min,+ A: 8 Triglyme lla+B:21oc, 1 hr 0.56 +A: 21oc, 30min 9 1/3 Triglyme lla+8 :21oc, 30min NP +A: 21oc, over night 10 lli+B :-2c, bringtor.t. NP +A:6oc, 1 hr 11 1/2 Trig 'Iyme IIi + B : -2 C 1 hr, bring to NP r.t., +A: 21oc, 30min 12 II + B : -7c bring to r.t. NR sft over night, + A : !f! in mol ratios of lla : B : A !f! !f! ratios of puk areas obtaind and idntifid by GC/MS 1 quipd with thrmal ionization dtctor. B : bor an-comp lxs 1 A : propionic
PAGE 38

25 Table 7 Reaction of p-Nitrostilbene with p-Toluenesulfonhydrazide Rul"' 2 3 !f. iii II a TSH sol vent 2.3 triglyme 2.3 DME 2.3 triglym II! in mo 1 ratio. react. condi t 1 ons 170 c, 1 Omin 135 c, 30 min KOH,s min 70C, 35 min no. of GC peaks 24 28 4 11 PNBB/IIa 1.73 0.72 0.21 0.11 :t: iii ratio ofp.
PAGE 39

26 summarized in Table 7. The best p-nitrobibenzyl/(IIa) ratio (1 .72) was obtained in Run 1, however there were large amounts of products and the quantitative separation was not attempted. Hydrogenation of p-nitrostilbene using rhodium as a catalyst Since rhodium is known to be a selective hydrogenation hydrogenation of (IIa) was attempted using rhodium on aluminum as a catalyst. The products included p-nitrobibenzyl, (IVa) and starting material. The ratio of p-nitrobibenzyl/(IVa) was Separation was not attempted. Oxidation of p-aminobibenzyl with peroxytrir1uoroacetic acid Peroxytrifluoroacetic acid is known to be a suitable oxidation reagent for aromatic amines. p-Aminobibenzyl (IVa) was oxidized with peroxytrifluoroacetic acid, following Pagano and Emmons' method. There were four products, including p-nitrobibenzyl and (IVa). The of pnitrobibenzyl/(IVa) was 1.12. Although this method seemed to be promising, the use of 90 % hydrogenperoxide to generate peroxytrifluoroacetic acid, discouraged us

PAGE 40

27 from running the reaction on a preparative scale. Grignard reaction with copper iodide catalyst It is known that copper(I)-catalyzed reaction of Grignard reagents and organo halides result in the cross-coupling reaction of different organic Benzyl magnesium chloride and p-nitrobenzyl bromide were reacted in the presence of copper iodide. pNitrobibenzyl was obtained along with bibenzyl and two other side products. The ratio of pnitrobibenzyl/bibenzyl was 0.26. Although the yield of p-nitrobibenzyl/bibenzyl was not appreciable, the separation using preparatory TLC was attempted. Although four distinctive spots were clearly separated on the small scale silica gel TLC plates with benzene as developing solvent, preparatory silica gel TLC exhibited twenty seven visual bands. Each major band was analyzed by GC/MS with only one fraction containing the desired product in insufficient yield.

PAGE 41

CHAPTER III RESULTS AND DISCUSSION 4 Based upon the conclusions of Stenberg, water would be expected as a reactant only if the reaction of the substituted bibenzyls are ionic. An ionic alterna-tive exists to the radical thermolysis pathway if quinone methides are from a'-hydroxy substituted bibenzyls.43 This is illustrated in Scheme 5. Scheme 5 x-@-7 x-@CH2 D + DO no exchange

PAGE 42

29 The quinone methides could subsequently react with water to form hydroxy cresols, a species which would not be expected from radical reactions. The reaction of both sets of models with deuterium oxide was expected to be most informative. The incorporation of deuterium into products from the sub-stituted bibenzyls would strongly suggest ionic reac-tions. The homolitic bond strength of H-OH in water is 119 kcal/mole, significantly higher than C-H bond (98 kcal/mole) or c-c bond in bibenzyl (61.6 kcal/mole)(Appendix 1). Consequently, in radical reac-tions water would not be expected to react sig-nificantly. This was the crux of Stenberg's explanation of his experimental observations with water and H 2s. If the reactions occur ionically, the effect of substituents should be significant. With a radical reaction pathway, the effect should be minimal. The effect of substituents on a reaction involving ionic intermediates can be most effectively studied by Hammett li f 1 t h" 44 If th 1 t f 1 k near ree-energy re a 1ons 1p. e p o o og vs. Hammett in a negative slope, that is Hammett p is negative, the rate determining step in-volves the process in which electron donating sub-stituents accelerate the reaction, either by stablizing intermediate or facilitating the leaving group. If p is

PAGE 43

30 positive, the rate limiting step is accelerated by electron withdrawing groups. Deviation from a straight line plot implies a change in overall reaction pathway as the nature of substituent is varied, or a shift in the rate limiting step within the overall reaction pathway. Corresponding for the substituents employed in our study are given in Table 8. All reactions were performed in a multireactor system at the US Department of Energy, Pittsburgh Energy Technology Center. Reaction conditions of for 3 hours at 4290 psi H 2o were employed in all cases. Due to the limited amount of reactor time avail-able to us at the Pittsburgh Energy Technology Center, only one sample was run in duplicate as a test of reproduciblilty (A#l, C#5). Inspite of the carefully controlled reaction conditions, the production of higher molecular weight compounds were inconsistent. Low molecular weight compounds were similar but product/internal standard ratios, as measured by in-tegrated area under the GC peaks, were inconsistent as well. Consequently, only qualitative discussions of the more interesting reaction pathways follows. The number of deuteriums incorporated into the products has been calculated by comparing M, M+l, M+2, 45 abundance ratios from the literature, with isotope

PAGE 44

31 Table 8 Hammett Values of Groups Used in the Reaction O"m O"p O"ind O"p+ O"pNH2 -0.16 -0.66 -0.12 -1.30 -0.15 t-Bu -0.10 -0.20 -0.07 -0.26 -0.13 CH3 -0.07 -0.17 -0.04 -0.13 H 0 0 0 0 0 CH30CO 0.37 0.45 0.34 0.46 0.64 EtOCO 0.37 0.45 0.21 0.46 0.64 CF3 0.43 0;54 0.41 0.61 0.65 NH3 + 0.86 0.60 0.61

PAGE 45

32 intensities reported as normalized to the intensity of M. The isotopic abundance ratios of reaction products are normalized to the highest intensity signal in the vicinity of the parent peak. When experimental M+1 value exceeded more than twice the literature value, it was assumed that some molecules had molecular weights which were increased by one, that is one deuterium was incorporated into it. Experimental M+2 was then normalized to experimental M+1 abundance ratios, and again compared with the literature value. When the M+2 value thus calculated exceeded more than twice the literature value, it was assumed that some molecules had molecular weight which were increased by two, and so on. There is no statistical basis for choosing twice the literature value as a criterion, but measured natural abundance ratios of the same compounds produced from different starting materials all fell within twice the literature value. The GC/MS results for all reactions are summarized in Appendix 2. 3-1 Substituted Bibenzyls where R H For the compounds where R= H, the reactions were run only in o2o.

PAGE 46

33 Toluene and substituted toluenes were the major low molecular weight products in all cases. Both com pounds were multiply deuterated (Appendix 2). The maximum number of deuteriums incorporated into these products do not correlate with substituent effects suggesting radical-like reactions. Stenberg (1980) indicated that water is not reactive as a hydrogen atom transfer agent under liquifaction conditions. His conclusion was based upon experimental evidence and the high homolitic bond energy of H-OH,4 as was discussed earlier. Inspite of this thermodynamic handicap, the incorporation of deuterium in our reaction products clearly suggests reaction with water. Such incorporation can be envisioned either radically or ionically, although the lack of corresponding hydroxyl compounds is puzzling. Hydroxy-substituted compounds may have been left in the aqueous layer, or may have polymerized to form high molecular weight compounds which were not identified at this stage. The most abundant components of the dichloromethane extract were deuterated starting materials. There was an observed trend to the maximum possible number of deuterium incorporated into the starting materials. That is, the more electrondonating

PAGE 47

34 Table 9 Product Distributions of Major Products OoH x-o-cH2CH3 X OH H OH H H20 0.22(1) 0.16 -NH2 020 NO NO NO NO H20 0.12 0.15 -CH3 020 NO NO NO NO H20 0.009 0.08 -H 020 0.062 NO 0.026 NO 50 40 H20 NO 0.017 -m-CF3 020 NO NO NO NO H20 NO -NO CH302C 020 NO NO NO NO (1) The numbers are the ratios of pentanollproduct, measured by thearea under the GC peaks. ND: not detected. number D: the number of possible deuteriums incorporated.

PAGE 48

35 Table 9 -continued Qca3 xVcH3 R OH H OH H H20 0.56 0.062 -NH2 020 NO 0.21 NO 0.12 3D 6D H20 0.27 -0.36 -CH3 020 trace 0.053 -3D H20 0.10 -0.32 -H 020 0.23 0. 13( 2 ) 0.15 0.13(2 ) 6D 3D 3D 3D H20 0.014 0.10 -m-CF3 020 0.069 0.16 0.053 0.064 6D 2D 3D 2D H20 0.13 0.083. -( -C02 H) CH302C 0.047 0.0685[ 020 0.18 0.14 0.0876D 3D trace 4 D (-C02H)4D (2) experimental value x 1/2

PAGE 49

36 Table 9 -continued starting materials rearranged compounds OH H OH H H20 0.84 OB -NH2 020 -1.44 NO NO SD H20 0.80 OB -CH3 020 1.85 OB NO 6D H20 1.01 -DB -H 020 1.51 2.39 DB NO 7D 3D H20 1.14 OB -m-CF3 020 1.34 L83 DB NO SD 2D H20 --NO CH302C 0.021 0.13 1D 020 (-C02H) 1 .35( -C02H) NO NO 3D 4D OB: observed. ND: not detected. number D: the number of possible deteriums incorporated

PAGE 50

37 Table 9 -continued cyclic compounds high m. wt. compounds OH H OH H H20 DB -DB -NH2 020 DB NO DB NO H20 DB -DB CH3 020 DB NO DB -H20 DB NO H 020 DB DB NO trace H20 ND -DB m-CF3 020 NO ND DB DB H20 NO -DB CH3D2C 020 NO ND DB NO 08: observed. ND: not detected.

PAGE 51

38 the substituents, the more deuterium that was incor-porated. Table 9 summarizes the major products. This would suggest that the electron donating group en-courages and stablizes the intermediates of the exchange process. Deuterium exchange may be envisioned by either radical or ionic pathways as illustrated in Scheme 6. Scheme 6 (R:X or H) R-@-cH2 xp-cH2CH2-@ 0 X -@-CH-CH2-@ D H D-0' Jr l 020 I D + x-Q-cH2CH2-@ + D OD e e H X -@-cH-CH2-@ l 020 D D If the reactions are radical, this would contradict Stenberg's conclusions and appear thermodynamically + H e + OD

PAGE 52

39 unfavorable. If ionic reactions are taking place, either aliphatic or aromatic substitutions are possible. Route B would be stablized by electron donating groups, but alcohol products would be expected and these have not been observed. Route C forms carbanion intermediates, hence electron withdrawing groups would be expected to stablize the intermediates. The electrophilic aromatic substitutions illustrated via route A agrees with the observed substituent effects, since electron donating groups would be expected to stablize the intermediate arenium ions. The deuterated products identified from these reactions are illustrated in Appendix 2. The formation of stilbenes from bibenzyl (IVd), and m-trifluoromethyl bibenzyl (IVe), are consistant with the radical mechanisms presented in Scheme 1 Phenanthrene, which was also observed, is also a possible product from radical reactions (Scheme 7).

PAGE 53

40 Scheme 7 (;Oi) f-(A) fH J I t.R H r R -r H ---7 (C)() The most intriguing reaction in this series was the reaction of the carboxylic acid methyl ester sub-stituted bibenzyl_(IVf). The most abundant dichloromethane soluble specie was the demethylated carboxylic acid (!Vg). The demethylation process is probably ionic, where water is acting as nucleophile (Scheme 8).

PAGE 54

41 Scheme 8 1 + ( IVg) (IVg) was also observed to decarboxylate to produce bibenzyl (IVd) as one of the major products. The decar-boxylation process can be envisioned either ionically, or radically (Scheme 9 and 10). Scheme 9 e o-c-{0;-cH 2CH2.0 0 D o .... 'o el D o-cQ-cH2CH2.0 II<) 0 l

PAGE 55

Scheme 10 --7 0 RD 42 l The maximum number of deuterium incorporated into biben-zyl produced from (IVf) was four. which was one more than the number of deuterium incorporated into the unreacted bibenzyl when bibenzyl was the starting com-pound. This suggests the substitution of a deuterium for the carboxylic moiety on the aromatic ring. 3-2 Substituted Bibenzyls where R = OH For the compounds where R = OH. the reactions were run in both H 2o. and o2o. There are two basic comparisons. One is the comparison between the products from the reaction in o2o when R = H (bibenzyls) and R OH (o-hydroxybibenzyls). Although strict quantitative

PAGE 56

discussions are not possible due to the poor reproducibility, simple comparisons were attempted. The other comparison is product distribution between reactions in the presence of H 2o and o2o. The products formed in each were similar. Generally, the 43 reactions proceeded more in H 2o than o2o; unreacted starting materials were less, and the. amount of reaction products were greater in H 2o. These results suggest the presence of a primary isotope effect. Every compound recovered from each reaction with o2o contained deuterium. The acidic hydrogen of the phenol was expected to be readily exchanged with deuterium from 0 20. Since phenolic hydrogens are well known hydrogen transfer agents in radical reactions,46 the observed distribution of deuterium through out the products was not surprising. The major low molecular weight products observed from a-hydroxy bibenzyls are: hydroxy toluene, sub-stituted toluenes, phenol and substituted ethyl ben-zenes. Hydroxy toluene and substituted toluenes are possible products of the bibenzyl thermolysis reaction. There was no clear indication of a substituent effect. Generally, the amount of products produced in H 2o were greater than in o2o.

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44 On comparing the thermolysis products between R = H, and R = OH, namely toluene and substituted toluenes from run A with a-hydroxy toluene and substituted toluenes from run C, there were no obvious trends in the number of deuteriums incorporated into the products. There were also no significant differences in the amount of products formed. These results demonstrate the dominance of radical thermolysis pathways even in the presence of supercritical water. Phenol and substituted ethyl benzenes are also possible products resulting from the cleavage of arylaliphatic bond. Neither compound was observed in the reaction, where R = H. The phenolic group could facilitate this cleavage, either ionically or radically as shown in Scheme. Alcohols, the expected products from ionic reactions were not identified. The radical fragments from the alternative homolitic cleavage may or may not react with o2o in order to incorporate deuterium. Unlike R = H, where o2o is the only possible deuterium source, the phenolic hydrogen will readily exchange with deuterium oxide resulting in a labile source of deuterium atoms. Upon comparing the amount of these compounds formed from the reactions with H 2o and o2o, the reactions with H 2o produced a larger amount of compounds. This would be expected if the formation of

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45 the keto tautomer was rate limiting. Within the reaction in the presence of H 20, the abundance of these products seemed to increase as electrondonating ability of sub-stituents increased. The reason for this trend is not obvious (Table 8, and Appendix 2-C). Scheme 11 x-o-cH2CH2p Hfo H x-o-cH2CH2'? 0 1 rad1cal () x-o-cH2CH2 + H x-o-cH2CH2 + l RH x-o-cH2CH3 (not found) + R Comparison of the amount of unreacted starting materials was consistant with previous discussions. More starting materials were observed in o2o than in H 2o, and more when R = H, than R = OH. More deuterium incorporation was observed with increasing electrondonating ability, but the trend was less clear than for R = H. 9 0 1 p

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o-Hydroxyethylbenzene was found only from the reaction of p-amino-a'-hydroxybibenzyl. Since the electrondonating ability of the amino group is larger than that of a hydroxyl group, a reaction such as that illustrated in Scheme 12 becomes feasible. Scheme 12 HO l Rearranged starting reactants were observed in 116 the p-NH2 p-CH3 H, and m-CF3 substituted cases, where R = OH. A proposed reaction pathway is illustrated in Scheme 13.

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Scheme 13 ----+) X Cyclization seems to have occurred in bo,th H 2o and o2o where the substituents were p-NH2 p-CH3 and H groups. No cyclization products have been identified 47 where substituents were eledtronwithdrawing groups. Two possible pathways for these products are illustrated in Scheme 14. The reaction of p-amino-a'-hydroxybibenzyl in o2o varied significantly from all other reactions. The amount of internal standard, pentanol, recovered was very small and the major product observed had a presumed parent ion of a mass of 394. The explanation for the anomaly remains elusive.

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48 Scheme 14 --7 (tA) X 1... X H 0 X H 0 lk l (JC':O 0 0 X X H Alternative () .X) ----7 (:(;)0 X H 0 X t.,:O 0 X H H e 't__....B l R() H!i.l' (JC':O X 0 0 X H te8

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49 3-3 Future Plans The establishment of quantitative reliability is our major priority. To this end, we recently purchased a Parr 22 ml microreactor which in other experiments has lead to highly reproducible results. Once quantitative reliability has been established, the suggested trends from this work can be confirmed. Particular focus will be on confirming the effect of substituents on deuterium exchange. Other ambiguous reaction pathways will also be tested through the use of radical scavengers such as cresol or tetralin. Alternative Lewis acid catalysts may also be added in an attempt to enhance ionic reactions. 3-li Conclusions The object of this thesis was to study the role of water under coal liquifaction conditions using substituted bibenzyls and a'-hydroxybibenzyls as coal models. The series of substituted bibenzyls and a'hydroxybibenzyls were synthesized via Wittig reaction followed by hydrogenation. The substituents synthesized for both bibenzyls and a'hydroxybibenzyls were p-NH2 p-CH3 H, m-CF3 and p-CH3o2c.

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50 The model compounds were reacted with H 2o or o2o under 4290 psi (0.30 kbar), at 400C for 3 hours. Thermolysis pathways dominated the reaction of substituted bibenzyls. The thermolysis products and recovered starting materials were observed to undergo deuterium exchange. The observation of exchange implies that previously unknown reactions are tak-ing place between supercritical water and the substituted bibenzyls. Mechanisms for these reactions were suggested. In the case of p-CH3o2c, demethylation, decarboxylation and deuterium substitution dominated. This suggests an ionic pathway. Comparison of the product distribututions between H 2o and o2o for the substituted a' hydroxybibenzyls indicates a primary isotope effect, although the thermolysis pathway again predominated. The a'-hydroxybibenzyls exhibited more deuterium exchange than with the simple bibenzyls. This may be due to the enhanced hydrogen transfer ability of phenolic hydrogen under radical reactions. The tautomerization pathways contributed significantly to the product distributions. They also exhibited a primary isotope effect which suggests that tautomerization is rate limiting. 2-Ethyl-4-substituted diphenyl ethers were observed and are possibly produced through the rearrangement of certain substituted a'-hydroxybibenzyls. Cyclization of p-NH2

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p-cH3 H, substituted a'-hydroxybibenzyls to dibenzodihydrooxepane was also observed. ( 51

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CHAPTER IV EXPERIMENTAL When anhydrous solvents were required, the solvents were dried over 3-A molecular sieves prior to use. All commercially available reagents were used without further purification. Melting points were measured on a Mel-Temp electrothermal melting point apparatus manufactured by Laboratory Devices. The thermometer used was uncalibrated and the reported melting points were not corrected for high altitude. GC/MS analysis were performed on a Hewlett Packard model 5890A mass selective detector. A typical temperature program consisted of elevating the temperature from 80C to 250C at 8C/min, with 1.6 min solvent delay. IR spectra were recorded on Perkin-Elmer 7108 infrared spectrophotometer.

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53 4-1 Synthesis 4-1-1 a-Bromo-p-toluic acid methyl ester In an Erlenmeyer flask, a-bromo-p-toluic acid (10 g, 0.0465 mol) was dissolved in 20 mL THF. The flask was placed in a dry ice/acetone bath. Ethereal diazomethane generated from 13.93 g (0.0651 mol) p-toluenesulfonylnitrosamide, was distilled into the flask. After distillation was completed, the flask was removed from the dry ice/acetone bath and allowed to come to room temperature while stirring. The completion of the reaction was detected by the disappearance of yellow color and vigorous foaming. After rotary evapora-tion of the solvent, a white solid was obtained (11 .96 g, 112 %, mp 30-160C). M/e (relative ionization): 228 + + + [18.6, M ], 197 [19.7, MCH3J, 149 [100.0, M -Br], 90 [78.0, 149 co 2cH3J. 4-1-2 Salicylaldehyde benzyl ether Benzyl bromide (15 mL, 0.126 mol) and potassium carbonate (18 g, 0.13 mol) were slowly added to a solu-tion of benzaldehyde (12.9 mL, 0.12 mol) in 75 mL acetone at room temperature. After refluxing for 3.5 hrs, the entire mixture was taken up in a large excess

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of H 2o at which point, a yellow oil separated. The oil was extracted with ether and washed with a sodium car-bonate solution. The solvent was evaporated and the oil distilled at 174-185C, 3 torr, yielding a yellow oil, 17.2 g (67.5 %). M/e (relative ionization): 212 [10.5, + + M ], 183 [21.0, MCHO], 121 [24.5, PhCHO], 91 [100, PhCH2J. --1-3 Salicylaldehyde acetyl ether Acetic anhydride, 150 mL, and potassium car-bonate, 150 g, was added to the solution of salicylal-dehyde (100 g, 0.82 mol) in 500 mL ether. The mixture was stirred at room temperature for 30 min, after which, solids were filtered off. Following rotary-evaporation of ether, the oil was taken up into water at which point a white solid separated. Recrystallization from petroleum ether gave 56 g (46 %) white needle, mp 36.5380C (38C).18 --1-Salicylaldehyde tetrahydropyranyl ether Dihydropyran (6.3 g, 0.075 mol) and pyridinium-p-toluenesulfonate (1.26 g, 0.05 mol) were added to a solution of salicylaldehyde (6.1 g, 0.05 mol) in 150 mL dichloromethane. The solution was stirred at room tern-

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55 perature for 4 hrs, 24 hrs, and 48 hrs. GC/MS of reac-tion aliquots indicated that only the reactants were present. 4-1-5 Pyridinlum-p-toluenesulfonate (PPTS) p-Toluenesulfonic acid monohydrate (28.5 g, 0.15 mol) was added to pyridine (69.5 mL, 0.74 mol) with stirring at room temperature. After stirring for 20 min, the excess pyridine was rotary-evaporated to produce a white solid. Recrystallization from acetone gave, white crystals, 37.7 g (73.7 %), mp 116-118C (120C).34 All bibenzyls were synthesized via phosphonates and stilbenes, as exemplified below by the synthesis of p-methyl-bibenzyl. 4-1-6 Diethyl-p-methylbenzylphosphate (Ic} a-Bromo-p-xylene (10.0 g, 0.055 mol) was dripped into triethylphosphite (9.6 g, 0.058 mol) with stirring over a period of 25 min at room temperature. The solu-tion was refluxed over night. Distillation at 107-122C, 3 torr, gave 12.2 g (86.5 %) of a clear colorless liq-+ uid. M/e (relative ionization): 242 [12.2, M ], 213 + + [5.2, M-Et], 105 [100, M -(EtO)lO]. This material was

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56 used without further purification. (IIc) Diethyl-p-methylbenzylphosphonate (Ic) (3.62 g, 0.015 mol) was dripped into the mixture of sodium hydride (0.31 g, 0.015 mol) in 50 mL dry dimethylethoxide with stirring at room temperature, followed by slow addition of benzaldehyde (1.5 g, 0.015 mol). After refluxing for 2 days, the mixture was taken up in a large excess of water, at which point, a taline solid was obtained. Recrystallization twice from 95% ethanol gave 2.08 g (71.5 %) of light yellow plates, mp 117-118C. (IVc) (IIc) (0.954 g, 3.18 mmol) was dissolved in 200 mL absolute ethanol. Palladium on carbon was added as catalyst. Following hydrogenation in a Parr hydrogenator at room temperature for 2-4 hrs, at 30 psi, the catalyst was filtered and the solvent evaporated to yield a tan solid g, 3.02 mmol (94.9 %)), which was pure by GC/MS. M/e (relative ionization): + + 196 [25, M ], 105 [100, M mp 25-26C 47

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57 p-Bromobibenzyl Bromine (4.31 g, 0.024 mol) was added slowly to the solution of stilbene (5 g, 0.027 mol) in 20 mL acetic acid, containing 0.05 g iron filing. The mixture was heated at 63C, for 4 hrs. The insoluble materials were filtered, and the solution was neutralized with 10 % sodium hydroxide, followed by extraction with ether. Rotary-evaporation of the ether gave a dark yellow oil containing 2 different isomers of monobromostilbene, stilbene and a small amount of dibromo substituted compounds, as evidenced by GC/MS. The desired product was not isolated. p-Nitrobibenzyl A) By hydroboration reduction. Borane-pyridine complex (0.12 g, 1.3 mmol) was dripped into the solution of p-nitrostilbene (0.3 g, 1.3 mmol) in 5 mL dry diglyme at room temperature. The mixture was refluxed at 210C for 30 min. After cooling to room temperature, propionic acid (0.078 g, 1.3 mmol) was added. The mixture was further refluxed for 30 min. The resulting mixture contained p-nitrobibenzyl and p-nitrostilbene with a GC peak area ratio of 0.56. Refluxing for an additional 60 min increased the amount of side products, resulting in

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a decrease of p-nitrobibenzyl/p-nitrostilbene ratio to 0.36. The products were not isolated. 58 B) By diimide reduction. A solution of ptoiuenesulfonyhydrazide (0.57 g, 3 mmol) in 3 mL triglyme was slowly added to a solution of p-nitrostilbene (0.3 g, 1.3 mmol) in 7 mL triglyme, at room temperature. As the temperature raised slowly, the solution started to foam. In 10 min, the temperature reached 170C at which point, the foaming subsided. GC/MS of the mixture indicated the presence of 24 compounds including pnitrobibenzyl. The GC peak ratio of p-nitrobibenzyl/pnitrostilbene was 1 .73. Purification was not attempted. C) By hydrogenation with rhodium catalyst. pNitrostilbene was dissolved in 100 mL/50 mL, ethanol/THF, to which rhodium on alumina (0.01 g) was added as catalyst. After shaking at room temperature, for 2 hrs. under 30 psi H 2 in a Parr hydrogenator, the catalyst was filtered. As analyzed by GC/MS, the solution contained p-nitrobibenzyl, p-nitrostilbene, and two other products. The GC peak area ratio of pnitrobibenzyl/p-nitrostilbene was 0.46. Purification was not attempted.

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59 D) By oxidation with peroxide. 90 % Hydrogen peroxide (0.744 mL, 0.0279 mol) was added slowly to 12 mL dichloromethane at room temperature, without stirring. The solution was then placed in an ice bath, followed by slow addition of trifluoroacetic anhydride (3.9 mL, 0.0279 mol) with stirring. The solution was stirred for 30 min as it was brought to room temperature at which point p-aminobibenzyl (1.1 g, 5.58 mmol) in 10 mL dichloromethane was slowly introduced by dropwise addition. After refluxing for 1 hr, the cooled solution was taken up in 20 mL water. The organic layer was washed with water, 10 % sodium carbonate, and again with water. After treatment with activated charcoal, and drying with magnesium sulfate, the solvent was evaporated. The dark brown oil thus obtained (0.34 g) contained p-nitrobibenzyl and p-aminobibenzyl with GC area ratio of 1.21. Four other minor products were also observed. Separation was not attempted. E) By cuprous iodide coupling. Cuprous iodide (1.63g, 8.5 mrnol) and triethylphosphite (0.28 g, 1.71 mmol) were added to a solution of p-nitrobenzylbromide (2.0 g, 7.66 mmol) in 20 mL THF. The mixture was cooled to -29C with an o-xylene/liquid nitrogen bath. A THF solution of benzyl magnesium bromide (11.5 mmol), syn-

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60 thesized from benzyl bromide (1 .52 g, 12.mmol) and magnesium (0.32 g, 13.2 mmol), was added slowly. The mixture was brought to room temperature while stirring for 2 hrs, after which 20 mL of ether was added. The mixture was washed.with sodium chloride solution. The light yellow solution thus obtained contained four compounds by GC/MS, including p-nitrobibenzyl, bibenzyl, p-nitrobenzylbromide and one other minor side product. The GC peak area ratio of p-nitrobibenzyl/bibenzyl was 0.26. Purification by preparatory silica gel TLC was attempted. Out of 27 bands which as been separated, only one band contained the desired product in insignificant yield. 4-2 Reactions A multireactor system at the US Department of Energy, Pittsburgh Energy Technology Center was employed for the reactions. The system consists of five in-"dividual microautoclaves, each of approximately 45 mL 48 capacity and attached to a single yoke. The entire assembly was immersed rapidly into a preheated, fluidized sand bath, allowing it to heat-up to reaction temperature in 4-6 minutes. Immersion in a second fluidized sand bath held at room temperature provided

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61 rapid quenching. The autoclaves were agitated by a rapid horizontal-shaking motion, assuring good mixing of heterogeneous, multiphase mixtures. Individual thermocouples allowed continuous temperature monitoring of each microautoclave. The reaction conditions were chosen so that 2.6 mmole of each compound was reacted in presence of 4.3 mL H 2o or containing 2 mL pentanol/93.4 mL H 2o, or 2 mL/100 g o2o, as internal standard. T-his resulted in the mole ratio of the reactant to standard of 2 : 1. Pen tane! was selected as standard since its solubility in water (16.6 g/100 mL at 20C) was just large enough to ensure the desired concentration, yet would favor partition into dichloromethane upon work up. All reactions were run at 400 C for 3 hrs. The pressure at reaction temperature was not measured directly in these experiments. Using van der Waal's equation, the partial pressure of water was estimated as 4290 psi. The density of supercritical water was 0.095 g/mL. After the reaction, the interior of the reactor was washed several times with a total of 5 mL dichloromethane. The dichloromethane, the aqueous mixture thus obtained was shaken so that equilibrium of the products between two layers was achieved. Each

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62 dichloromethane layer was analyzed by GC/MS using two different GC columns. Methyl silicone coated 25 m capillary column was used for lower molecular weight compounds under standard conditions, and 12 m, DV I capillary column for higher molecular weight compounds, with temperature elevation of 8C/min, from 80C to 300C. Table 10 summarizes the reaction.

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63 Table 10 Summaries of the Reactions Run X R System A CH3o2c OH Vf D 2 D 2 m-CF3 OH Ve D 2 D 3 H OH Vd D 2 D 4 CH3 OH Vc D 2 D 5 NH3 OH Ve D 2 D B CH3o2c OH Vf H 2 0 2 m-CF3 OH Ve H 2 0 3 H OH Vd H 2 0 4 CH3 OH Vc H 2 0 5 NH3 OH Ve H 2 0 c NH3 H IVe D 2 D 2 H H IVb D 2 D 3 CH3o2c H IVf D 2 D 4 m-CF3 H IVe D 2 D 5 CH3o2c OH Vf D 2 D

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REFERENCES 1. a) J. B. Hannay, J. Hogarth, Proc. R. Soc. London, 29, 324 (1874) b) J. B. Hannay, J. Hogarth, Ibid., 30, 178 (1880) 2. M. A. McHugh, V. J. Krukonis, "Super Critical Fluid Extraction", Butterworths (1986) 3. G. A. Wiltsee Jr., Quarterly Technical Progress Report for the Period July 1983 -Sept. i983, Prepared for the u. S. Department of Energy, Office of Fossil Energy, Under Cooperative Agreement DE-FC01-38FE60181,17 4. V. I. Stenberg, R. D. Hei, P. G. Sweeny, J. Nowack, Am. Chern. Soc. Div. Fuel Chern. ?reprints, 29(5), 63 (1984), and references cited there in. 5. G. v. Deshpande, G. D. Holder, A. A. Bishop, J. Gopal, I. Wender, Fuel, 63, 956 (1984) 6. P. Barton, Ind. Eng. Chern., Process Des. Dev., 22 589 (1983) 7. D. s. Ross, J. E. Blessing, Q. C. Nguyen, G. P. Hum Fuel, 63, 1206. (1984) 8. D. S. Ross, Q. C. Nguyen, G. P. Hum, Ibid.,63, 1211 (1984) 9. M. E. Paulaitis, M. T. Klein, A. B. Stilles, DOE Quarterly Report, DE-FD22-82PC50799, July-Sept. (1983) 10. B. D. Blaustsin, B. C. Bochrath, H. N. Davis, M. A. Mikita, Am. Chern. Soc. Div. Fuel Chern. ?reprint 30(20), 359 (1985) 11. M. A. Mikita, H. T. Fish, Ibid., 31 (4), 56 (1986) 12. H. T. Fish, M. A. Mikita, Abstact Am. Chern. Soc. 193rd National Meeting, April 6; 1987, Denver Colorado

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65 13 0 P. s. Virk, Fuel, 58 J 148 (1979) 1 4 0 R. A. Miller, s. E. Stein, Am. Che;m. Soc. Div. Fuel Chern. ?reprint, 24 (2) J 271 ( 1979) 15. L. w. Vernon, Ibid., 24(2), 143 (1979) 16. Y. Sato. Fuel, 58, 318 ( 1979) 17. D. C. Cronauer, W. L. Kehl, Ind. Eng. Chern. Fundam., 17, 291 (1978) 18. B. M. Benjamin, Fuel, 57, 378 (1978) 19. D. D. Whitehurst, EPRI Report AF-480, 9-44 (1977) 20. R. E. Miller, S.C. Stein, J. Phys. Chern., 85, 580 ( 1 981 ) 21. R. Livingston, H. Zeldes, M.S. Conradi, J. Am. Chern. Soc., 101, Li312, (1979)" 22. D. s. Ross, J. E. Blessing, in "Coal Liquifaction Fundamentals, ACS Symposium Series 139", D. D. Whitehurst ed., 301, (1980) 23. S. W. Benson, H. O'Neal, "Kinetic Data on Gas Phase Unimolecular Reactions", National Bureau of Standards, NSRDS-NBS21 (1970) 2Li. L. M. Vernon, Fuel, 59, 102 (1980) 25. M. L. Poutsma, Ibid., 59, 335 (1980) 26. Y. Kakemura, H. Itoh, K. Ouch!, Ibid., 80, 379 (1981) 27. Fieser and Fieser, Reagents for Organic Synthesis vol.1, 191, John Wiley (1967) 28. G. Wittig, Organic Syntheses, vol LIO, 66 (1960) 29. G. Koslapoff, "Organophosphorus Compounds" Chapt. 7, John Wiley (1950) 30. F. A. Carey, R. J. Sunberg, "Advanced Organic Chemistry, second ed.,Part A", Plenum Press (198Li)

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31. T. Makin, N. Nierenstein, J. Am. Chern. Soc. 53 239 (1 931) 32. N. Miyashita, A. Yoshikoshi, P. A. Grieco, J. Org. Chern., 42, 3772 (1977) 33. J. H. Van Boom, Synthesis, 169 (1973) 34. C. B. Reese, R. Saffhill, J. E. Sulston, J. Am. Chern. Soc., 89, 3366 (1967) 35. M. Miyano, et al., Nippon Nogei Kagaku Shi, 34(8) 683 (1960) 36. R. E. Litz, et. at., J. Org. Chern., 12, 617 (1947) 66 37. H. C. Brown, K. Murray, J. Am. Chern. Soc., 81, 4180 ( 1 959) 38. Fieser and Fieser, Reagents for Organic Synthesis vel. 8, 50 (1980) 39. G. E. Ham, W. P. Coker, J. Am. Chern. Soc., 194 ( 1 964) 40. R. E. Dewey, E. E. van Tamalen, J. Am. Chern. Soc. 83, 3729 (1 961) 41. G. E. Pagano, w. D. Enmons, Organic Syntheses, vel. 49, 47 (1969) 42. H. Alper, ed., "Transitionmetal Organometallics in Organic Synthesis", vel. 1, 114, Academic Press (1976) 43. H. U. Wagner, R. Gompper, in "The Chemistry of the Quinoid compounds, Part 2", S. Patai, ed., John Wiley, 1145 (1974) 44. P. Sykes, "A Guide Book to Mechanism in Organic Chemistry, sixth ed.", 358, Longman (1986) 45. R. M. Silverstein, G. c. Bassler, T. c. Morrill "Spectrometric Identifaication of Organic Compounds, fourth ed.", John Wiley (1981) 46. Y. Kamiya, T. Yao, S., Oikawa, in "Coal Liquifaction Fundamentals, ACS Symposium Series 139", D. D. Whitehurst ed.,291, Am. Chern. Soc. (1980)

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47. R. L. HinMan, K. L. Marnm, J. Am. Chern. Soc. 81, 3294 (1959) 48. R. R. Anderson, B. C. Bockrath, Fuel, 63, 329 (1984) 67

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Appendix 1 68 HOMOL VT I C BOND STRENGTH H-OH eromet i c C-H prim. C-H sec. C-H benzylic C-H 11 9.0 < 1) keel /mole 110.6 (2 ) 97.9 (2 ) 94.6 ( 2 ) 81.9 (2 ) bi benzyl c-c 61.8 ( 2 ) (57) (4 )) (1) J.McMurry, "Organic Chemistry, 2nd ed.", Brooks and Cole (1988) (2) S.'w' .Benson, "Thermochemical Kinetics, 2nd ed." 'w'iley, ( 1976) (3) D .F .McMillan, D .M .Golden, Annu. Rev. Phy s. Chem., 33 493 (1982) (4) D.S.Ross, J.E.Blessing, "Coal Liquifaction Fundamentals: ACS Symposium Seires 139", Am. Chem. Soc., 301 (1980)

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69 Appendix 2 R Anelysis of the Dichloromethane Extrecteble Compounds by GC/MS m.wt. (1) Compound i dent i f1 ed no. of D X formula i nco r po rated Mess spectrum dete (2) m/e [relative intensity] Mass Literature values <3 ) retention sample H20 time Exp. values 1 (5 ) no. i nt. stand ( 4 ) comp retention sample D20 time Exp. values 2 no. int. stand comp (1) Suggested strtusture is drawn with [ ] (2) Mass spectrum data of the raction in the presence of water. (3) R.M.Silverstein1 G.C.Bassler 1 T .C.Morril11 "Spectrometric lndentification of Organic Compounds 1 4th ed. "1 John Wiley and Sons ( 1 981 ) (4) The ratio of integrated GC peak areas. (5) Mass abundances are normalized to the highest peak at the vicinity of the parent peak

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70 AppendiX 2 -A 108 Q-cH3 C7HeO OH CH3C1 09[53, M+ L 1 07[1 00, M+-HL 90[32, M+H20] I II 0 77[42, B] 107 109 109 110 111 112 113 114 100 77.3 0.43 5.60 e H20 0.129 100 97.7 10.4 5.21 78.5 0.89 100 76.0 40.1 OH A D20 6D 0.047 100 52.8 5.02 3.2 25.4 77.5 100 94.1 42.0 12.7 c D20 6D 0.097 100 30.0

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71 Appendix 2-A (continued) 94 Q-oH C6H60 CH3CII 0 94 95 96 97 98 99 100 6.62 0.38 B H20 ND OH A D20 ND 4.21 100 91.3 22.1 cs D20 SD 0.013 100 24.0

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72 Appendix 2-A (continued) 136 CaHaO 0 CH3C-136[59, M+], 119[51, M+OH], 91 [100, M+-C02Hl II 0 135 136 137 138 139 140 141 100 8.85 0.75 8'*1 H20 6.3 100 10.6 OH A'*1 D20 4D 84.0 100 87.3 29.5 71.4 100 81.8 50,2 18.1 c D20 5D 100 35.7

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73 Appendix 2-A (continued) 198 H-o-CH2CH2-) c14H14 o H-0 CH3C198 [23 I M+ L 1 07 [ 1 00 I M + .0' CH2] II 0 198 199 200 201 202 203 204 205 100 15.4 1.30 13.75 a H20 0.040 100 17.6 .. 13.72 OH A 020 70 0.054 100 77.6 13.71 75.1 100 76.6 64.2 cs 020 70 0.022 100 83.5

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74 Appendix 2-A (continued) 226 H-a-c-o-cH2CH2-() other II u n; dent; f; ed c1sH14o2 peeks CH3CII 0 226 227 228 229 100 16.5 1.68 8 H20 NO v OH A01 D20 NO v 16.05 cs D20 0.021 100 100 63.2 30 v

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A p p e n d X 2-B H H H H NH2 C*l H C*2 CH30C II 0 C*3 m-CF3 c 92 c 7 H 8 90 1.94 020 0.205 92 C7He 90 1.94 020 0.264 92 C7He 90 1.94 020 0.180 5.9 92 C7He 90 1.94 020 0.160 5.0 75 @-cH3 3D 91 92 93 94 95 96 100 7.69 0.25 27.6 100 86.8 23.2 5.4 0.8 100 23.2 13.1 @-cH3 3D 91 92 93 94 95 96 100 7.69 0.25 22.7 90.7 100 42.5 10.4 1.4 100 23.0 3.3 @-cH3 3D 91 92 93 94 95 96 100 7.69 0.25 33.7 100 94.2 38.6 10.2 1.8 100 26.0 4.6 @-cH3 3D 91 92 93 94 95 96 100 7.69 0.25 37.5 100 86.0 24.1 3.0 100 28.0 3.4

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A p p e n d i )( 2-B cont. H H H H NH2 c 020 H c 020 CH30C II 0 c 020 m-CF3 c 020 107 c 7 H 8 0 107 5.34 100 0.121 3.4 136 c8H8o2 136 8.32 100 0.140 41.5 160 C8H7f3 159 2.22 0.064 14.9 76 NH2 -@-cH3 5D 108 109 11 0 111 112 113 7.73 0.46 15.4 61.8 100 61.8 30.7 7.7 100 49.6 12.0 Hoc-@-cH3 II 0 4D 137 138 139 140 8.85 0.75 100 97.8 46.5 14.5 100 31.2 CF3 2D 160 161 162 163 100 8.76 0.34 57.2 100 46.5 7.9 100 11.2

PAGE 90

A p p e n d )( 2-B cont. H H H H NH2 c 020 H c 020 CH30C II 0 c 020 m-CF 3 c 020 77 197 NH2-@CH2CH2-@ C14H15N 50 197 198 199 200 201. 202 203 204 14.48 100 15.8 1.16 1.440 6.3 11.4 64.3 100 91.7 45.8 12.4 2.9 100 27.0 6.3 182 H-@CH2CH2-@ C14H14 3D 179 180 1 81 182 183 184 185 186 11 .1 8 100 15.4 1.1 0 2.387 60.4 100 100 40.7 7.4 100 18.2 240 CH 2 CH 2 -@ 0 C16H1602 10 240 241 242 243 11.15 100 17.6 1.86 0.245 100 41.0 12.6 5.4 100 30.7 13.2 250 C15H13 f3 CF3 20 248 249 250 251 252 253 254 11.06 100 16.4 1.26 1.832 100 66.2 44.4 11.1 1.8 100 25.0 4.1

PAGE 91

A p p e n d 1 X 2-B cont. H H H H NH2 ct D20 H C'*2 D2D 162 CH30C u 0 C14H14 11 .15 c D20 0.245 m-CF3 c D20 78 H-@CH2CH2-@ 4D 160 181 162 163 164 165 166 187 100 15.4 1.10 8.5 5.6 13.2 65.0 100 50.5 19.0 5.5 100 37.6 1 0.1

PAGE 92

A p p e n d 1 )( 2-B cont. H H H H NH2 C#l 020 H c 020 CH30C II 0 c 020 m-CF3 c 020 79 226 CH2CH2-@ 0 C15H1402 40 226 227 228 229 230 231 16.1 B 100 16.5 1.68 1.352 48.3 100 93.2 52.8 23.6 6.5 100 27.5

PAGE 93

A p p e n d X 2-B cont. H H H H NH2 C'*1 020 H C'*2 020 CH30C II 0 C'*3 020 m C'*4 020 80 180 H-@-CH=CH-@ c14H12 10 176 177 178 179 1.80 181 182 13.14 100 15.3 1.09 11.8 7.8 49.7 100 100 49.9 11.8 0.086 100 23.6 248 c15H11F3 CF3 10 247 248 249 250 13.0 100 16.4 1.25 26.3 100 53.1 12.8 0.025 100 24.2

PAGE 94

A p p e n d X 2-B cont. H H H H NH2 c 020 H c 020 CH30C II 0 c 020 m-CF3 c 0 20 81 176 c14H1 o 2D 176 177 178 179 160 13.93 100 15.3 1.09 39.4 19.9 100 51.9 39.4 0.031 100 75.9

PAGE 95

A p p e n d X 2-B cont. H H H H NH2 c 020 H c 020 CH30C II 0 c 020 m-CF3 c 020 82 197 C14H15N ( NH2 -@-CH CH3 J @ 40 195 196 197 198 199 200 201 14.75 100 15.8 1.16 0.033 7.6 23.2 46.8 100 81.8 34.3 14.0 100 41.9

PAGE 96

A p p e n d j X 2-B cont. H 83 30 195 196 197 198 199 200 201 202 16.56 ct __ 1_5._B __ 1._16 __________ H CH30C II 0 0.264 6.2 21.2 47.9 100 97.8 46.6 12.0 2.3 100 25.7 4.9 H c-3 H c 4 o 2 o 1-------+----------------------------_,

PAGE 97

84 Appendix 2 -C 160 CeH7F3 CF3 30 CF3 160 [32, M+l 141 [to,M+;. Fl, 91 !too,M+-cF3l 158 159 160 161 162 163 100 8.76 0.34 B H20 2.23 4.5 31.8 100 7.7 0.100 OH 2.23 A 020 22.0 85.1 100 37.1 7.1 0.053 100 18.7 92 @-cH3 C7H8 30 H 92 [51, M+ L 91 [100, M+-H] 89 90 91 92 93 94 95 96 100 7.64 0.25 B H20 1.95 100 50.7 6.1 0.006 0.321 100 12.1 1.3 OH 1.94 A 020 1..6 3.4 17.8 86.9 tOO 52.5 15.5 2.2 0.145 100 29.5 4.2

PAGE 98

85 Appendix 2-c (continued) 174 SQ,>-cH 2CH3 CgHgF3 CF3 CF3 174 [25, M+L 159 [100, M+-CH3) 155 [ 11 ,M+Fl 105 [18, M+-CF3] 174 175 176 100 9.87 0.43 6'*2 H20 3.13 100 0.017 OH A'*2 020 NO 106 @-cH2CH3 CaH1o 40 H 1 06 [24' M+ L 91 [ 1 00' M+ -CH3 I 105 106 107 108 109 110 100 8.80 0.34. 6'*3 H20 2.76 21.3 100 19.1 0.080 OH 2.74 A'*3 020 30.7 100 58.3 26.2 0.026 100 44.9

PAGE 99

86 Appendix 2-c (continued) CF3 B H20 OH A 020 94 @-oH C5H50 40 H 94 [100, M+ ),66 [50,Cp] 94 95 96 97 98 99 100 6.62 0.38 B H20 4.27 100 10.9 0.009 OH 4.13 A 020 91.3 100 16.5 0.062

PAGE 100

86 Appendix 2-c (continued) CF3 B H20 OH A 020 94 @-oH C5H50 40 H 94 [100, M+], 66 [50, Cp] 94 95 96 97 98 99 100 6.62 0.38 B H20 4.27 100 10.9 0.009 OH 4.13 91.3 100 16.5 A 020 0.062

PAGE 101

87 Appendix 2-c (continued) 108 <9(-oH C 7 H 6 0 CH3 CF3 60 108 [100 1 M-+), 107 [ 98 1 M+H), 90 [311 M+H20] 77 [55 I B.] 107 108 109 110 111 112 113 114 100 7.73 0.46 B H20 5.21 98.3 100 12.2 0.026 OH 5.14 12.5 A 020 57.4 75.8 100 65.6 28.5 0.064 100 43.4 108 <9(-oH CH3 C 7 H 8 0 50 H 108 [1001 M .. ], 107 [76 IM+H], 77 [50 I B.] 107 108 109 110 111 112 113 114 100 7.73 0.46 B H20 5.16 75.6 100 13.2 0.102 OH 5.07 A 020 2.3 16.3 53.9 100 76.7 32.9 11.1 0.227 100 42.9 14.5

PAGE 102

88 Appendi>< 2 -c (continued) 266 CF3 HO CF3 Cts H13 F30 50 266 [ 7. M+ L 159 [6, M+-CH2-Ph-OH ] 107 [1 00, M+-CH2-Ph-CF3] 266 267 268 269 270 271 272 273 100 16.5 1.47 B62 H20 13.64 100 20.6 1.5 1.143 OH 13.62 A62 020 50.0 100 81.3 31.2 7;8 1.6 1.341 100 25.2 5.2 196 HO C14H140 70 H 198 [ 15, M+L 107 [ 1001 M+-CH2-Ph ]1 91 [ 27. M+-CH2-Ph-OH ] I 77 [ 20 I Ph. ] 198 199 200 201 202 203 204 205 206 100 15.4 1.30 B63 H20 13.70 100 24.9 3.6 1.012 OH 13.69 A63 020 21.4 23.9 23.9 54.9 100 100 53.3 18.2 3.2 1.508 100 15.6

PAGE 103

89 Append1x 2C(continued) 266 ( J CF3 CH2CH3 CF3 Cls H13 F30 60 266 [48, M+], 251 [ 100, M+CH3), 231 [ 23,251-HF 1 181 [11, 251 -CF3 1 266 267 268 269 270 271 272 273 100 16.5 1.47 B-2 H20 13.21 100 19.8 0.048 OH 13.18 A 020 3.7 38.2 100 98.4 50.2 16.8 4.7 0.171 100 33.2 9.3 198 ( @ro-i)Q) J c,4H14o CH2CH3 60 H 198 [59, M+ ), 183 [ 1 00, M+CH3 1 165 [ 41 M+-331 77 [ 33, Ph 1 198 199 200 201 202 203 204 205 206 100 15.4 1.30 B H20 13.16 100 20.8 0.042 OH 13.10 A 020 5.6 12.3 45.5 98.3 100 80.7 24.8 5.8 0.210 100 30.7 7.1

PAGE 104

90 Appendix 2 -c (cont 1 nued) CF3 B#2 H20 OH A#2 020 194 C14 H10 0 30 H 194 [ 100, M+ L 165 [62, M+CHO] 194 195 196 197 198 100 15.4 1.29 B#3 H20 13.29 100 21.6 o:o36 OH 13.26 A#3 020 20.9. 100 27.8 0.033

PAGE 105

91 Appendix 2 -c (cant i nued) CF3 B.-2 H20 OH A.-2 020 194 [@C@J c14 H10 o 5D H 194 ( 100, M+ ], 165 [62, M+CHO] 1 07 ( 39 I CH2-PH-OH J 194 195 196 197 199 199 200 100 15.4 1.29 B.-3 H20 13.97 100 21.6 0.053 OH .95 A.-3 020 75.0 100 97.5 45.9 13.0 0.029 100 52.! 14.9

PAGE 106

92 Append1x 2 c CH3 6#4 H20 OH A#4 020 93 @-NH2 C 6 H 8 N NH2 93 [ 100, M+), 66 [61, Cp] 91 92 93 94 95 100 6.98 0.21 B#S H20 3.99 2.4 162 100 10.3 0.7 0.062 OH A#S 020 NO

PAGE 107

93 Appendix 2c (continued) 106 CH3-@-CH3 CH3 C5H1o 3D 106 ( 37, M+ ], 91 [ 1001 M+-CH3] 102 103 104 105 106 107 108 109 100 8.80 0.34 B H20 2.84 3.6 16.7 5.4 57.6 100 10.2 0.364 OH 2.86 A 020 23.1 50.3 100 86.9 28.4 0.053 100 32.7 107 NH2-@-CH3 C7HgN NH2 1 07 ( 65 I M+ ], 1 08 ( 1 00 I M+-H ]1 77 (16,Ph] 106 107 108 109 100 8.09 0.29 BS H20 5.36 100 64.9 4.4 0.003 0.551 100 6.8 0.39 OH As 020 NO

PAGE 108

94 Appendix 2 c (cant i nued) 120 CH3-@-cH2CH3 CH3 C9H12 120 [ 24, M+ ], 105 [ 100, M+-CH3] 120 121 122 100 9.92 0.44 8#4 H20 3.99 100 9.3 0.148 OH A*'4 020 NO 121 @-NH2 C 8 H11N NH2 121 ( 29, M+ ], 106 [ 100, M+-CH3] 119 120 121 122 123 100 9.20 0.38 a.es H20 6.68 6.5 38.2 100 19.1 1.5 0.163 OH A*'S 020 NO

PAGE 109

95 Appendix 2 c (cent i nued) 94 @-oH CH3 C5H50 94 [ 100, H+), 66 [ 33, Cp] 94 95 96 100 6.62 0.38 6'*'4 H20 4.09. 100 7.8 0.190 OH A*'4 D20 ND 94 @-oH C5H50 NH2 94 [ 100, H+), 66 [51, Cp] 92 93 94 95 96 100 6.62 0.38 es H20 4.06 5.2 38.0 100 13.3 1.6 0.220 OH A*S D20 ND

PAGE 110

96 Appendix 2c (continued) 118 CH3-@-cH=CH2 CH3 CgH1o 11 8 [ 811 M+ L 117 [ 1 00 I M+ -H L 91 [ 30 I CH3-PH ] 115 116 117 118 119 120 100 9.98 0.44 8#4 H20 4.46 39.1 10.0 12.3 100 9.1 0.092 OH A#4 020 NO NH2 B .. 5 H20 OH A .. 5 020

PAGE 111

97 Append1 x 2 c (cant i nued) 106 0{-oH c 7 H 8 o CH3 50 CH3 108 [1001 M+ L 107 [96 I M+H 1., 91 [ 81 M+OH] 77 [ 47 1 Ph] 107 108 109 110 111 112 113 100 7.73 0.46 B H20 5. t 1 96.2 100 11.0 0.270 OH 5.27 A-4 020 60.0 100 77.1 40.4 trace 100 50.3 106 0{-oH c 7 H 8 0 CH3 NH2 109 [1001 M+ L 107 [75 I M+-H], 91 [91 M+OH] 77 [ 37 1 Ph] 107 108 109 110 111 112 113 114 100 7.73 0.46 es H20 5. t t 74.9 100 1.9 0.51 OH A-s 020 NO

PAGE 112

98 Appendix 2 -C'(cont 1 nued) CH3 B#4 H20 OH A 020 122 (Q(cH2CH3 OH CaHtoO NH2 122(38, M+ ], 107(100, M+-CH3], 77(43, Ph] 121 122 123 124 100 8.84 0.54 Bs H20 '6.33 13.7 100 16.2 0.056 OH As 020 NO

PAGE 113

99 Appendix 2 c (cant i nued) 212 CH3 C15H150 ( J CH2CH3 70 121 [ 37 I M+ ], 197 [ 1 00 I M+CH3 ], 182 [ 14 I 197 CH3 1 120 [ 15, M+92 L 91 [ 19, CH3-Ph 1 212 213 214 215 216 217 218 219 100 16.5 1.47 664 H20 14.09 100 20.4 0.103 OH 14.06 A64 020 34.1 83.2 100 8.41 49.4 22.0 0.101 100 45.2 NH2 as H20 OH As 020

PAGE 114

100 Appendix 2c (cont1nued) 206 ( C15H120 CH3 CH3 208 [ 100, M+ L 179 [15, M+271, 178 (23, M+-28] 165 [ 25, 179 -CH2 ] 205 206 207 208 209 210 100 16-.4 1.45 B#4 H20 14.40 25.9 100 17.3 0.112 OH A#4 020 trece 209 ( ;@C@ J H2N O C14H11NO NH2 209(100, M+ L 180 [27,M+-29], 104 [ 12,M+-102] 209 210 211 212 100 15.7 1.35 B#S H20 17.65 100 22.9 2.9 0.196 OH A*'S 020 NO

PAGE 115

101 Appendix 2c (continued) 212 C15H150 HO 60 CH3 212 [ 24 I M+ ], 1 07 [ 50. M+ -CH3-Ph-CH2 ] 1 05 [ 1 00 I M+ -HO-PH-CH2 ) 212 213 214 215 216 217 218 219 100 16.5 1.47 8#4 H20 14.61 100 22.0 1.7 0.797 OH 14.59 A-4 020 35.7 44.2 100 86.6 71.3 42.1 18.0 5.0 1.850 100 42.7 11.8 213 NH2-@CH2 CH2 C14H1sNO HO NH2 213 [ 8,M+ ], 106 [ 100, M+ HO-PH-CH2] 213 214 215 100 15.8 1.36 B#S H20 16.62 100 18.6 2.3 0.835 OH A*S 020 NO