Title: Polymerization studies of 4-substituted-1, 2, 4-triazoline-3, 5- diones and synthesis of model compounds related to triple strand polymers
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Title: Polymerization studies of 4-substituted-1, 2, 4-triazoline-3, 5- diones and synthesis of model compounds related to triple strand polymers
Alternate Title: Synthesis of model compounds related to triple strand polymers
Physical Description: ix, 157 leaves. ; 28 cm.
Language: English
Creator: Turner, S. Richard, 1942-
Publication Date: 1971
Copyright Date: 1971
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Subject: Polymers and polymerization   ( lcsh )
Chemistry thesis Ph. D   ( lcsh )
Dissertations, Academic -- Chemistry -- UF   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
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Thesis: Thesis - University of Florida.
Bibliography: Bibliography: leaves 153-156.
General Note: Manuscript copy.
General Note: Vita.
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Bibliographic ID: UF00098941
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 001029730
oclc - 18114675
notis - AFB1832

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POLYMERIZATION STUDIES OF

4-SUBSTITUTED -1 24-TRIAZOLINE-3, 5-DIONES

AND

SYNTHESIS OF MODEL COMPOUNDS

RELATED TO TRIPLE STRAND POLYMERS








By

SAM RICHARD TULNm'R








A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF

THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE

REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY









UNIVERSITY OF FLORIDA

1971
















This dissertation is dedicated to my parents.















ACKNOWLEDGEMENTS

My stay at the University of Florida has been a pleasant and

rewarding experience and I would like to offer my gratitude to the

many people who have made this experience possible.

I will be forever indebted to my advisor, Dr. George B. Butler,

for his patience, understanding, encouragement and guidance during

the course of this work.

I wish to thank Dr. W. R. Dolbier, Dr. J. A. Deyrup, Dr. M. T.

Vala and Dr. R. B. Bennett for giving of their valuable time to serve

on my supervisory committee. Also I wish to thank Dr. T. Hogen Esch

for his informing discussions with me on portions of this work.

The successful completion of this work would not have been

possible without the assistance of Dr. Lawrence J. Guilbault. His

enthusiastic and tireless research efforts have been and will always

be a great example for me.

Grateful thanks are extended to my fellow laboratory colleagues.

They have generated a pleasant and stimulating environment in which

to work.

I also wish to acknowledge the Air Force Office of Scientific

Research, the Petroleum Research Fund and the Tennessee Eastman

Company for providing financial support in the form of research

assistantships.

Finally, I wish to thank my wife, Pamela, for her love and under-

standing which have made the completion of this work an easier task.















TABLE OF CONTENTS


Page

ACKNOWLEDGEMENTS . . . . . . . . . . iii

LIST OF TABLES . . . . . . . .... . . . . v

LIST OF FIGURES . . . . . ... .... . . vi

ABSTRACT . . . . . . . . . . . . vi

CHAPTER

I. INTRODUCTION . . . . . . . . . . 1

A. Polymerization Studies of Azo Dienophiles .. 1
B. Triple Strand Polymer Model Compound Studies 9

II. POLYMERIZATION STUDIES OF 4-SUBSTITUTED-1,2,4-
TRIAZOLINE-3,5-DIONES . . . . . . . . 14

A. Copolymerization of Ethyl Vinyl Ether and Divinyl
Ether with 4-Phenyl-1,2,4-triazoline-3,5-dione 14
B. Copolymerization of 4-Phenyl-1,2,4-Triazoline-
3,5-dione with Other Monomers . . . . .. 46
C. Reactions and Attempted llomopolymierizations of
4-Phcnyl-1,2,4-triazoline-3,5-dione . . .. 53
D. Diels Alder Polymers . . . . . . . 58

III. TRIPLE STRAND POLYMER MODEL COMPOUND STUDIES . . 66

A. Attempted Synthesis of Tetracyclo[4.4.0.13'9.1 ]
Dodecane and Related Systems . . . ... 66
B. Attempted Synthesis of 5,5,6,6-Tetrasubstituted
Cyclohexadiene Structures . . . . . .. 82

IV. EXPERIMENTAL . . . . . . . . .. 86

A. General . . . . . . . . . . 86
B. Copolymerizations and Related Reactions of 4-
Substituted-l,2,4-triazoline-3,5-diones . .. 87
C. Syntheses Related to Triple Strand Model Compound
Studies . . . . . . . . . . 121

REFERENCES CITED . . . . . . . . . . . 153

BIOGRAPHICAL SKETCH . . . . . . . 157














LIST OF TABLES


Table


Copolymerizations of EVE and PhTD . . . . . .

Copolymerizations of DVE and PhTD . . . . .

First Order Rate Constants in PhTD at 25C . . . .

Summary of Interception Reaction Results . . . .

Copolymerizations and Reactions of PhTD and Other
Monomers . . . . . . . . . . . ....

Summary of Catalyzed PhTD Reactions . . .

Catalytic Hydrogenation of Diazoquinone Adducts . ..

Reactions of Tetracyanoethylene with a-Pyrone . .


Page

29

31

37

43


47

57

81

83















LIST OF FIGURES


Figure Page

1 Nmr spectrum of the copolymer of ethyl vinyl ether and
4-phenyl-1,2,4-triazoline-3,5-dione. . . . .. 16

2 Nmr spectrum of 3-phenyl-6-vinyloxy-l,3,5-triaza-
bicyclo[3.2.0]hepta-2,4-dione . . . . . .... 18

3 Nmr spectrum of the copolymer of divinyl ether and
4-phenyl-l,2,4-triazoline-3,5-dione . . . . .. 21

4 Nmr spectrum of the copolymer of divinyl ether and
4-methyl-l,2,4-triazoline-3,5-dione . . . . .. 22

5 Plot of M versus reaction time for EVE-PhTD in CH2,C
at 25C . . . . . . . . . . . 34

6 Nmr spectrum of 3-oxa-2,2-dimethyl-4-ethoxy-8-phenyl-
1,6,8-triazabicyclo[4.3.0]nona-7,9-dione . . . ... 38

7 Nmr spectrum of l-(formy]nethyl)-2-acetyl-4-phenyl-
1,2,4-triazoline-3,5-dione . . . . . . ... 49

8 Nmr spectrum of the Diels Alder, ene adduct of 4-phenyl-
1,2,4-triazoline-3,5-dione and styrene . . . ... 63

9 Nmr spectrum of the Diels Alder, ene polymer from styrene
and bis triazoline dione . . . . . . . .. 64

10 Plot of consumption of PhTD versus time for EVE-PhTD
in dioxane at 250C . . . . . . . .... ... 110

11 Logarithmic plot of [PhTD] /[PhTD or A /A versus time for
EVE-PhTD in dioxane at 25 .... . . . . 111









Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in Partial Fulfillment
of the Requirements for the Degree of Doctor of Philosophy

POLYMERIZATION STUDIES OF
4-SUBSTITUTED-1,2,4-TRIAZOLINE-3,5-DIONES
AND
SYNTHESIS OF MODEL COMPOUNDS
RELATED TO TRIPLE STRAND POLYMERS

By

Sam Richard Turner

June, 1971

Chairman: Dr. George B. Butler
Major Department: Chemistry

The research described in this dissertation consists of two main

areas of investigation. The first area pertains to the use of azo

dienophiles, particularly 4-phcnyl-l,2,4-triazoline-3,5-dione, in

polymerization studies. The second area involves attempts to synthe-

size model compounds related to proposed triple strand polymers.



A. Polymerization Studies of 4-Substituted-l,2,/-triazoline-3,5-diones

The copolymerization and reactivity of the very potent cyclodien-

ophile, 4-phenyl-l,2,4-triazoline-3,5-dione (PhTD), with electron rich

coreactants were investigated. PhTD was found to spontaneously react

with vinyl ethers at room temperature in methylene chloride solution.

Ethyl vinyl ether (EVE) and isobutyl vinyl ether (IVE) were observed

to copolymerize spontaneously with PhTD to form 1:1 alternating co-

polymers. Divinyl ether (DVE) was observed to form a mixture of the

2+2 cycloadduct and copolymer at room temperature. At 60*C, only copol-

ymer was formed.

The structures of the copolymers were assigned from spectroscopic

and chemical data. Some physical property characterizations of the


vii








copolymers were made.

A propagation mechanism involving the coupling of dipolar inter-

mediates was ascertained as the most probable mechanism of polymeriza-

tion.. Numerous experimental observations were in support of this pro-

posed method of polymerization.

When the spontaneous copolymerizations of EVE and IVE were effected

in acetone or cyclohexanone, the corresponding 1,3,4-tctrahydrooxadia-

zine compounds were obtained as well as the expected copolymers. These

new heterocyclic ring structures were fully characterized. The com-

pounds were believed to result from an interception of the initial 1,4-

dipole intermediate by the weakly dipolarophilic alkyl ketone. DVE was

noted to form only a trace of the corresponding oxadiazine structure.

The difference in the reactivity of EVE and DVE was explained in

terms of the stability of the positive center of the 1,4-dipole.

Other olefinic compounds were reacted with PhTD. Vinyl acetate

was observed to undergo a unique intramolecular rearrangement of the

initially formed 1,4-dipole. Divinyl carbonate only resulted in 2:1

copolymers. N-vinyl carbazole spontaneously copolymerized to yield

a 1:1 copolymer of significantly higher molecular weight than obtained

in the vinyl ethers. The electron poor olefins, divinyl sulfone and

acrylonitrile, were found to be unreactive with PhTD.

Some decomposition reactions of PhTD were studied. Attempts to

catalytically homopolymerize PhTD were unsuccessful. The reaction of

PhTD with nucleophiles like sodium cyanide in dimethylformamide and

triethylamine resulted in the formation of 3,7-diphenyl-l,5-diazabicy-

clo[3.3.0]octa-2,4,6,8-tetraone as well as an unidentified oligomeric

product.







A new bis dionophile, 4,4'-(4,4 -diphcnylmethylene)-bis-l,2,4-

triazoline-3,5-dione, for use in cycloaddition polymerizations was syn-

thesized. It was found to spontaneously react with styrene to give a

high polymer believed to have been formed by first a Diels Alder re-

action and then an ene reaction.



B. Synthesis of Model Compounds Related td Triple Strand Polymers

Two dienes, 2-acetoxymethyl-l,3-butadiene and 2,3-di-(acetoxy-

methyl)-l,3-butadiene, were synthesized by a new sulfone pyrolysis pro-

cedure. The precursor acetoxy sulfones were prepared in good yields

from the corresponding bromides by use of silver acetate in acetonitrile.

The Diels Alder reactions of these acetoxy dienes and the corresponding

dihydroxy diene from the 2,3-diacetoxy diene were studied with p-benzo-

quinone. A facile aronatization or dehydrogenation of the adduct, de-

pending on the conditions, precluded its isolation.

2-Cyclohexene-l-one was found to react sluggishly with the 2-

acetoxymethyl diene. Attempts to force the reaction yielded polymeric

materials. Diazoquinone reacted with the disubstituted dienes to yield

the expected Diels Alder adducts. Various attempts at catalytic hydro-

genation of these adducts were not successful.

Tetracyanoethylene was found to be unreactive with a-pyrone.

Fumaronitrile and p-benzoquinone resulted in the expected adducts.

Bromination of 3,4-dimethylbutadiene sulfone and then dehydro-

bromination resulted in the corresponding 3,4-dimethylthiophene-l,l-di-

oxide. This compound was found to be unreactive with tetracyanoeth-

ylene, but it gave a double Diels Alder adduct with maleic anhydride.















CHAPTER I

Introduction

A. Polymerization Studies of Azo Dienonhiles

Reactivity of azo dienophiles

Compounds containing dienophilic nitrogen to nitrogen double bonds

have been extensively studied as reactants in cycloaddition reactions.

Normally these azo compounds have been shown to be more dienophilic

than their carbon counterparts. For example azodicarboxylates, 1, have

a stronger dienophilic reactivity than the corresponding fumarates, 2.1


N ,NC02R H CO R
RO2C 2 RO2C H

1 2

However, at the time this research was initiated only one report of the

use of these compounds as monomers in polymerization studies was

recorded.2 This account involved the copolymerization of ethyl azo-

bisformate with the comonomers tetrafluoroethylene, acrylonitrile and

methyl methacrylate. In each case some incorporation of the azo com-

pound into the polymer was verified by elemental analysis. No other

structural characteristics were reported.

4-Phenyl-l,2,4-triazoline-3,5-dione (PhTD), 3, has been shown by

Sauer and Schroder to be the most reactive of the azo dienophiles and

perhaps the most reactive dienophile known. The authors compared the

reactivity of PhTD with tetracyanoethylene by utilizing competition

experiments with 2-chloro-l,3-butadiene. PhTD was observed to react









about one thousand times faster than tetracyanoethylene, which had been

previously described as one of the most potent dienophiles synthesized.4

With the same diene,maleic anhydride, 4, was found to react only about

one half as fast as the tetracyanoethylene. Hoi.ever, with other

dienes tetracyanoethylene reacted as great as 106 times faster than 4.



Copolymerization studies

The structure of 4-substituted-l,2,4-triazoline-3,5 diones is very

similar to that of the carbon to carbon double bond dienophiles maleic

anhydride and N-substituted maleimides, 5. The latter compounds have

been utilized extensively as comonomers in copolynerization studies.

It was expected, then, "a priori" that these nitrogen analogues of maleic
H H H H
N--N Cb C /C'

0 ) 0 KA '0 0 Z0
Phl R

3 4 5

anhydride and the maleimides would undergo similar copolymerizations

with the appropriate electron rich comonomer.

Cyclocopolymerization, originally reported by Butler,6 has evolved

as an extremely important research area in polymer chemistry, not only

because of the theoretical significance of the reaction but in the main

because some of the cyclocopolymers have been shown to be active anti-

tumor agents. Because of this importance, the mechanistic and prepar-

ative aspects of cyclocopolymerization have undergone a careful system-

atic study. The general mechanism proposed was that of an alternating

intra-inter molecular propagation6 as shown below for the divinyl ether-

maleic anhydride system which is the most thoroughly studied of all the








cyclocopolymerization-systems. Since the initial mechanistic proposal,

evidence consistent with the participation of a donor acceptor complex




0 R 0
R-' R '











R 00 0


0-- ( ,) Z: 0V O





as a comonomer has been presented.8 More recently the divinyl ether

maleic anhydride system has been observed to polymerize thermally in

the absence of a free radical initiator and this has been interpreted

as additional evidence for the participation of a donor acceptor

complex in the copolymerization.

Since 4-substituted-1,2,4-triazoline-3,5-diones are known to be

better dienophiles than the usual electron poor comonomers in cyclo-

copolymerization, it was thought that they might behave as electron

acceptors in the presence of electron rich 1,4-dienes and participate

in cyclocopolymerization. Furthermore, it seemed a distinct possibility,

because of their great reactivity, that a spontaneous cyclocopolymer-

ization might possibly be triggered.

The degradation approach to proving polymer structures is important.








For example, the cyclic structure resulting from the copolymerization

of diallyl quaternary aamronium salts was verified by the following

degradation procedure.10



C -1. to hydroxide 31. 1E I (CH3) N
+ -2. to hydroxide
NBr 2. heat 3. heat
C!3 CH3 crosslinked
H3 3 C3 3 polymer
r J n



No such proof of the cyclic structure of the cyclocopolymer

systems has been possible to this time. If a 2:1 cyclocopolymer were

to form, the unique characteristics of the triazoline dione moiety

would offer a convenient handle to chemically probe the polymer

structure by the general degradation procedure shown below.



O0- --N-N--
N-N N
O N 0 base H H N2

Ph H/
0H low molecular
N weight products
ih
SL -rn

For the preceding reasons,as well as the desire to build new

cyclic copolymer structures to be tested as anticancer agents, the

behavior of 4-substituted-l,2,4-triazoline-3,5-diones with electron

rich olefins was investigated.



Nitrogen backboned polymers

At the commencement of this research no nitrogen backboned polymer

had ever been reported. If homopolymerization of an azo dienophile







could be effected through the nitrogen to nitrogen double bond,
obviously such a polymer with a nitrogen backbone would result. A
report by Iuisgen of the participation of ethylazobisformate in a
substitution reaction with fluorene proceeding by a free radical chain
mechanism made a free radical polymerization of such an azo dienophile
an attractive possibility.


12 --- 21.


SH

+ R~N-N\R





SN-N PH
R R


(-+ IH

H R= --CO2C2CH3


@~ 0)0
H /N-<
R R

SYNH
i-


By envisioning the results of such a successful polymerization
of a 4-substituted-l,2,4-triazoline-3,5-dione, one would have at hand
structure 6. Since such structures are readily hydrolyzable in strong


-NN

K t 6


base, a polyhydrazine structure, 7, would be distinctly possible.
These nitrogen backboned structures might possess practical value as
well as, assuredly, possessing theoretical importance. As another



K- r 7








goal of this research, the homopolymerization of 4-substituted-1,2,4-

triazolinc-3,5-diones, was investigated.

In the course of this work, Pirkle and Sticklerl2 reported the

homopolymerizarion of 4-n-butyl-l,2,4-triazo'ine-3,5-dione by initiation

with visible irradiation. These authors presented strong evidence that

the polymer obtained, indeed, possessed a nitrogen backbone.



Dials Alder polymers

Although the number of chemical reactions investigated in organic

chemistry is irmense, those that have been successfully adapted to

yield high polymers are few. Two types of cycloaddition reactions

have met with considerable success in producing high polymers, i.e.,

1,3-dipolar cycloadditions3 and Diels Alder reactions.14

The Dials Alder reaction has developed into the most profitable

application of the use of cycloaddition reactions to form polymers.4

To adapt the Diels Alder reaction to a polymer forming system whereby

the polymer is built up by stepwise Diels Alder cycloadditions requires

that the reactants be made difunctional. Two different approaches

have been utilized. The first involves the reaction of a bis diene

and a bis dienophile, generally referred to as an A-A, B-B system. One

example5 is the reaction of p-benzoquinone, 8, with the acetal prepared

from 2-hydroxymethyl-l,3-butadiene and acetaldehyde, 9.





Co H CH-2 O
-C 0









The second general approach has utilized an A-B monomer or an

intramolecular dicne, dienophile. The reaction of the substituted

Ct-pyrone, 10, and p-phenylene bismaleimide, 11, is a good example of

this approach.16

0 i0 00



00 0 0

10 11
F 0 0 -

CHR -R I ---- polymer
q__. C O-- R -NI
A H 3 Ci2 0
L 0 0



The main limitation and drawback to the use of the Diels Alder

reaction has been the difficulty in obtaining high molecular weight

products. In a polymerization propagation that follows step growth

kinetics, as is the case in a Diels Alder polymerization,7 the degree

of polymerization DP follows the Carothers equationl8 DP = 1/l-p,

where p is the extent of reaction. This means that the reaction must

be practically quantitative before a high molecular weight product is

obtained. For example a reaction with a 98% conversion only yields

a DP of 50 or, in other words, a low average molecular weight.

Hence, any stepwise polymerization reaction that is subject to

side reactions of any significance will not be suitable for formation

of high molecular weight products.

Two main reasons have been put forth for the inability, in most

instances, of Diels Alder polymerizations to achieve high molecular

weights.19 The first involves the ease by which the retrodiene








reaction can occur and the second concerns the chain growth of the

diene under the reaction conditions. Another complicating factor in

some systems has been the precipitation of the rigid ladder type polymer

causing a premature termination.15

Since the Dials Alder reaction is a thermally catalyzed reaction

and these two complicating factors also are enhanced at higher temper-

atures, it is not surprising that the problem of obtaining high

molecular weight has plagued its use in producing high polymers.

Stille20 and coworkers have successfully circumvented the retro-

diene reaction by employing bis dienes such as bis a-pyrones and his

cyclopentadienones that lose carbon dioxide or carbon monoxide respec-

tively and hence prevent the degradative retrodiene reaction from

occurring. An example has been the successful use of 3,3'-(oxydi-p-

phonylene)bis(2,4,5-triphenylcyclopentadienone), 12, and p-phenylene

bismaleimide, 11.20 A polymer with an intrinsic viscosity of 1.01

was obtained in four hours in refluxing 1,2,4-trichlorobenzene.


Ph

O -0 + 11
r-'
Ph
12 2

0 Ph Ph 0
S ----Ph -- Ph


0 Ph Ph 0



Another possible route to circumvent the bothersome side reactions

would be to employ extremely reactive reactants that would not need to









be heated in order to obtain the necessary high conversions. Obviously,

a bis 1,2,4-triazoline-3,5-dione would be expected to serve in this

capacity because of its fantastic reactivity. Hence another objective

of this research was the synthesis, and polyn:erization with bis dienes,

of such bis dienophiles.



B. Triple Strand Polymer Model Compound Studies

Thermal stability of ladder polymers

The synthesis and study of thermally stable polymers have been

extremely active areas of polymer chemistry research in recent years.

The extensive accounts cf such research recorded in the chemical

literature attests to the theoretical and practical importance of this

work. No attempts will be made to review these accounts since a recent

book1 and several reviews222324 are readily available.

Physical polymer properties have generally been found to be

related to the molecular weight of the polymer. These structure-

property correlations have established that polymers with ladder or

double strand structures, 14, possess extremely high thermal stability.23

For example polydiallydiphenysilane, having structure 13 was observed

to have enhanced thermal stability over its non-cyclic counterpart








Sir
HC \C6H5 n
5 6 6 -13
25
prepared from the monoallyl derivative.. The reason advanced for the

thermal stability of such cyclic structures is that thermal bond








cleavage which occurs -within the cyclic polymer repeat units of the

backbone does not lead to a lower molecular weight polymer. It is

obvious that thermal bond cleavage in the non-cyclic structures results

in a lower molecular weight as depicted in 14a and 14b.




14a 14b

Therefore one goal that the polymer architect has striven for in

the design of materials possessing thermal stability has been the

synthesis of ladder or double strand polymers. Needless to say, many

different researchers have been successful in using the double strand

polymer concept in preparing materials resistant to thermal breakdown.


Possible triple strand polymers

As an extension of the ladder polymer concept of thermal stability

a triple strand polymer would be expected to possess thermal properties

reflected from a structure that requires three bond cleavages per ring

to cause a decrease in molecular weight. Two possible approaches to

constructing such a polymeric species are: 1) a formation of a tubular

polycyclohexane, 15, from a triply initiated chain reaction of benzene





1000-


15

and 2) a triple 1,4-polymerization of a monomer such as 16 to yield

structure 17.
















16 17



Model compound studies

Generally, one of the objectives of this research was the

preparation and studies of model compounds related to these two

possible routes envisioned to triple strand polymers.

Much effort has been extended in the attempted synthesis of

tetracyclo[4.4.0.13'9.1 4'8dodecane, 18, the repeat unit of the

tubular polycyclohexane polymer.






18

The first approach has involved the homo Diels Alder reaction of

cis 4,5-diallylcyclohexene derivatives, 19.26a To date this approach

has not been successful.



jI- 1_88



19

The second approach has utilized 1,3,5-trisubstituted cyclobexane







derivatives 20 and 21. The tri ester 21 has been successfully prepared

26b
and failed to undergo the desired cyclization to 18. A compound,

which would lead to a nitrogen analogue of 18, 22, has been successfully

prepared but also failed to yield the cyclic structure 23.27




SF 18


20



R e 4 0 e R= -CHC02C2C H CH
base 2 2 2 3


18
\0
21

0
0 -N



O0CPNhIh NZOC :==0 _'0


22 23

The synthesis of compounds such as 24, which are functionally

capable of undergoing an intramolecular base catalyzed cyclization, is

the basis of the third approach to 18. One objective of this work





S 2CH s 2


24

was the preparation of compound 24, and other related structures as 25,

and cyclization of them to their respective cage structures 26.








0
H20Ms base




25 26

A fourth approach to 18, which was also studied as a part of this

research, was the possible intramolecular Diels Alder reaction of 28

to 18. A route to 28 was envisioned by the well documented 1,4-

elimination of bromine by zinc in dimethylformamide28 of 27,29 the

Diels Alder adduct of p-benzoquinone and 2,3-di(bromoethyl)-l,3-buta-

diene.
0.
0 0



0 2


27 28

In order for a monomer like 16 to be polymerizable by a triple

1,4-initiation it is immediately obvious that monomers such as 29 and

30, which are steric models for 16, would have to be subject to a 1,4--

polymerization. Hence another objective of this research was the

synthesis of 5,5,6,6-tetrasubstituted cyclohexadienes like 29 and 30

and the study of their polymerizations.




CN


29 C 0 H3
N CN 0/ CH3

29 30 CH 3














CHAPTER II

Polymerization Studies of 4-Substituted-1,2,4-triazoline-3,5-diones

A. Copolymerization of Ethyl Vinyl Ether and Diviny Ether with

4-Phenyl-l,2,4-triazoline-3,5-dione

Structure of the copolymers

4-Phenyl-l,2,4-triazoline-3,5-dione (PhTD), 3, spontaneously

copolymerized with ethyl vinyl ether (EVE) in methylene chloride

solution at room temperature and the product was shown to have a 1:1

composition by elemental analysis and nmr analysis. The copolymer was

found exclusive of any 2+2 cycloadduct (1,2-diazetidine), 31a.



a: R= -CH2CH3
H2C--CH-O-R
I b: R= -CR=CH2

0 =Z3 ) 0
Ph

31

Cycloadditions of ethyl azobisformate, 32, a similar azo dienophile,

have been shown to occur through both nitrogen to give 1,2-diazeti-

dines, 33, or through one nitrogen and one carbonyl oxygen to give

oxadiazines, 34. Therefore, structure 35, where propagation occurred

through one nitrogen and one carbonyl oxygen, and structure 36, where

propagation takes place through the nitrogen to nitrogen bond, appeared

to be the most likely candidates for the structure of the copolymer.

The nmr spectrum (Fig. 1) did not distinguish between the two













N
\ N 20_2CR R02 C N- N O2R
NZN 2 2
\ 2W C 33
2 32



RO2C-N 0
'OR

34

possibilities since the observed resonance signals were consistent

with either structure. The signals were 67.50 (broad, aromatic

hydrogens, 5), 66.05 (broad, hydrogen adjacent to two electronegative

atoms, 1), 63.90 (broad, methylene hydrogens of ether, 4) and 61.20

(broad, methyl hydrogens of ether, 3).



CH- CHI


i- 2
Ph CH Ph
CH3 n-



35 36

The infrared data, however, indicated that 35 was the predominant

repeat unit of the copolymer structure. A strong 1610 cm.1 absorbance

was observed and it was assigned to the -C=N- chromophore which is

only present in 35. Oxadiazine structures like 34 have exhibited
-I
absorbances in the 1630-1680 m.-1 region and they were assigned to

the -C=N- chromophore.30 A recent report on the infrared spectrum of
-l
N-cyclohexylacrylaldimine, 37, has assigned an observed 1608 cm.-

band to the -C=N- chromophore.31 Stickler and Pirkle12 synthesized
Stickler and Pike synthesized








































I I I I I
7.0 6.0 5.0 4.0 3.0 2.0 1.0
PPM (6)

Figure 1. Nmr spectrum of the copolymer of ethyl vinyl ether and 4-phenyl-1,2,4-triazoline-3,5-dione.











CDC
CC :C=N_




37

38, 39 and 40 as model compounds in a recent study of the homopolymer-

ization of triazoline diones. A strong 1605 cm.-i absorbance was

observed in 38 and not in 39 and 40.



C 11 C6 H CH C6 11 H
00 3 1 3

o0mQ -OCHi3 o0 300o),
N NN
CH3 CH3 CH3


38 39 40

Neither PhTD nor its precursor 4-phenyl urazole had an infrared
-1
absorbance in the 1610 cm.1 region. This information, along with

that obtained from the model compounds, appears as solid evidence for

the assignment of 35 as the predominant repeat unit of the copolymer.

In contrast to the EVE system, divinyl ether (DVE) and PhTD were

observed to form a mixture of copolymer and an adduct at room temper-

ature in methylene chloride. When the reaction was done at 60C only

copolymer was isolated.

The adduct from the room temperature reaction was isolated in pure

form and was assigned as the 1,2-diazetidine, 3-phenyl-6-vinyloxy-1,3,5-

triazabicyclol3.2.0]hepta-2,4-dione, 31b. The infrared spectrum gave
-l
no 1610 cm. absorbance, but gave strong vinyl ether absorbances at

1645 cm.- and 1625 cm. The nmr (Fig. 2) spectrum gave resonance



























0o










I I i 1 I

7.0 6.0 5.0 4.0 3.0 2.0 1.0
PPM 2,)

Figure 2. Nmr spectrum of 3-phenyl-6-vinyloxy-1,3,5-triazabicyclo[3.2.0]hepta-2,4-dione.








signals at-67.40 (singlet, aromatic hydrogen, 5), 66.60 (quartet,

vinyl hydrogen, 1), 65.90 (triplet, hydrogen next to vinyloxy on ring,

1), 64.50 multiplee, vinylic and ring methylene hydrogens, 4). The

mass spectrum yielded the correct molecular ion and the elemental

analysis agreed with the calculated value.

On warming an unpurified mixture of polymer and adduct to 600C,

a ring opening polymerization occurred. This was noted by the

disappearance of the 65.90 triplet in the nmr spectrum and the formation

of a product which gave identical spectral data as the original 60C

copolymer.

An elemental analysis of the copolymer was indicative of a 1:1

structure and for such a copolymer three structures were probable. The

first two, 41 and 42, were analogous to the EVE case in which only one

double bond is consumed and the third, 43, was precedented by cyclo-

copolymerization in which both double bonds are consumed.





N-N F7N-N --CH-CH-
0= -0Gl-CH-- O .:O0 9
N P N

CHC
Ph OH Ph 2
CH2 n 42 J
41









On the basis of spectroscopic and chemical evidence, repeat unit

41 appeared to predominate. First, the ab:senice of upfield resonances

in the nmr spectrum indicated that there were no methylene units

flanked by saturated carbon atoms. Since a requirement for the cyclic

structure 43 would be upfield resonances, this structure was eliminated.

The resonance signals observed (Fig. 3), 67.48 (broad, aromatic

hydrogens, 5), 66.30 (broad, vinylic hydrogen and hydrogen adjacent to

two heteroatoms, 2) and 64.20 (broad, methylene and vinyl hydrogens, 4),

were consistent with both structures 41 and 42.

The infrared spectrum of the copolymers, as in the EVE copolymers,
-i
showed a strong 1610 cm.- band and this was assigned to the -C=N- unit.
-I
Also present in the infrared spectrum were bands at 1640 cm. and
m-1 32'33
860 m.-1 due to the vinyl ether chromophore.3233
-1
As insurance that the 1610 cm. band was not associated with

the aromatic moiety, a copolymer of DVE and 4-methyl-l,2,4-triazoline-

3,5-dione was prepared. This copolymer also exhibited the strong
-i
1610 cm. absorbance. The nmr spectrum of this copolymer is given

in Fig. 4.

Catalytic hydrogenation of the DVE copolymer over palladium on

alumina at atmospheric pressure resulted in the absorption of the

theoretical amount of hydrogen for a structure like 41 or 42. The
-i
resulting material exhibited a new 2770 cm.- band due to the saturated

carbon hydrogen stretch, and loss of 1640 cm.- and 860 cm.- bands
-i
of the pendant vinyl group in the infrared spectrum. The 1610 cm.

band also disappeared. New resonances appeared in the nmr spectrum

at 63.90 and 61.20. These signals had the same chemical shifts as

the ethyl protons in the EVE copolymers.









































I I I I I I
7.0 6.0 5.0 4.0 3.0 2.0 1.0
PPM (6)
Figure 3. Nmr spectrum of the copolymer of divinyl ether and 4-phenyl-l,2,4-triazoline-3,5-dione.










































I I I I I I I I
7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0
.PP (6)

Figure 4. Nmr spectrum of the copolymer of divinyl ether and 4-nethyl-1,2,4-triazoline-3,5-dione.









One discrepancy in the hydrogenation results was the disappearance
-l
of the 1610 cm. band in the infrared spectrum. This was thought to

be due to an isomerization over the alumina catalyst for the following

reasons. The -C=N- linkage has been shown to be resistant to

catalytic hydrogenation30 when it appeared in oxadiazine structures

like 34. The catalytic hydrogenation of the EVE copolymer was carried

out as a control and although no hydrogen was absorbed, the loss of

the 1610 cm.-1 band was noted. A plausible explanation is that the

catalyst promotes an isomerization from structure 35 to the structure

bonded through both nitrogens, 34. If this were the case, a decrease

in the molecular weight of the copolymers should be observed since

such a change would require bond breaking and then bond reformation.

This was exactly what was observed as a DVE-PhTD copolymer had a

molecular weight of 1590 before hydrogenation and 490 afterwards. An

attempt to use palladium on carbon as the catalyst only gave a

partial hydrogenation.



Physical characteristics of the copolymer

The copolymers of EVE-PhTD and DVE-PhTD were white, highly

electrostatic solids which were soluble in most organic polar solvents.

Maximum number average molecular weights (M ) were normally in the

1000 to 3000 range and were measured by vapor pressure osmometry CVPO)

in acetone solution. The polymeric materials were low melting and

both copolymers softened around 100-110C.

A molecular weight distribution (Mw/Mn) of 3.36 was obtained for

one DVE-PhTD sample from gel permeation chromatography CGPC). The

determination was made in dimethylformamide and a calculation of the









M from the GPC trace gave a value of 2500 versus 2750 from the VPO.
n
An attempted GPC analysis of an EVE-PhTD copolymer was unsuccessful due

to what was believed to be a degradation of the polymer in the highly

polar solvent.



Spontaneous copolymerizations

Since the copolyrnerization of EVE and PhTD was certainly a

spontaneous copolymerization, the literature was reviewed to obtain

examples of previous spontaneous copolymerizations. Spontaneous

copolymerizations are differentiated in this discussion from other
34
types of photoinitiated spontaneous copolymerizations and Lewis acid

catalyzed spontaneous copolymerizations35 by defining a spontaneous

copolymerization as one that occurs when two olefinic monomers are

mixed in bulk or in solution at room temperature or lower with no

additional initiator involved.

All observations of spontaneous copolymerizations reported in

the literature have involved an olefinic monomer pair in which one

partner was electron rich and the other electron poor. Apparently,

the first report of such a copolymerization was disclosed in a

Canadian patent authored by Miller and Gilbert.36 They reported the

spontaneous copolymerization of vinylidene cyanide and alkyl vinyl

ethers. No mechanistic interpretation of their results appeared.

Yang and Gaoni37 have prepared 1:1 copolymers from the spontaneous

reaction of trinitrostyrene, 44, as the acceptor or electron poor

olefin and either 4-vinyl pyridine,45, 2-vinyl pyridine or p-dimethyl-

aminostyrene as the donor or electron rich olefin. The authors

suggested that the monomers formed an initial donor acceptor complex














+ 6 copolymer


45 44
which initiated the radical copolymerization of the monomers.
38
Kosover38 has suggested that the copolymerization is initiated by

the formation of a ground state donor acceptor complex which goes

to an excited ion pair state which then copolymerizes the surrounding

ground state donor acceptor complexes according to the equation shown

above. Such a mechanism is designated by Kosower to be a "T-Class

Reaction" in which the electron transfer in the complex is brought

about by thermal energy. The general equation38 for this reaction,


r D--A-

DAtz ( (DA A.) D +A



L "D-A-


proposed by Kosower, includes formation of a ground state complex (D,A)

which experiences a thermally induced electron transfer to the excited

ion pair form CD., A.) and then can go to products or can disassociate

to the separate ion pair excited state.

Butler and Sharpe939 have reported two other systems which fit

the definition of spontaneous copolymerization. One system in which

this type reaction occurs is the cyclocopolymerization of maleic








9
anhydride and DVE, and the other is the cyclocopolymerization of

divinyl sulfone and DVE.39 Both systems are believed to form a

donor acceptor complex which then goes to an excited state, couples

to form a diradical and thus initiates the copclymerization of

either completed or uncomplexed comonomers.



Mechanism of EVE and DVE copolymerizations

PhTD has been shown to undergo 2+2 cycloadditions with both

indene and p-dioxene.0 The cycloaddition with indene has been show,

to involve a dipolar intermediate since this 1,4-dipolar species has

been trapped with water. p-Dioxene formed the expected 2+2 adduct

plus a lot of discarded polymeric material.

In light of these results and in light of the polymer structures,

the most plausible propagation mechanism is believed to be the initial

formation of a stable 1,4-dipole. This intermediate, in the EVE

system, then went directly to copolymer, while in the DVE system it

formed the 1,2-diazetidine 31b and copolymer. At 600C, the diazetidine

is proposed to open to the initial 1,4-dipole and couple intermolecular-

ly to form the copolymer 41.

The difference in behavior between the EVE and DVE systems can

be rationalized in terms of the stabilities of the positive centers

of the respective 1,4-dipoles. The acid hydrolysis of EVE has been

observed to be 350 times faster than the acid hydrolysis of DVE.40

This difference is due to the stability of the corresponding oxonium

ion intermediates, 47 versus 48. The same positive center stabilization

occurs in the two 1,4-dipoles. Therefore it is believed that the more

stable 1,4-dipole (EVE) has a more pronounced dipolar character and









+ +
00 C/ 0 OCH2 H C
3


47' 8

links intermolecularly, while the energetically higher DVE dipole

closes to the strained 1,2-diazetidine.

The exact nature of the transition state leading to the 1,4-dipole
38
is not known. Kosower has proposed that 2+2 cycloadditions which

are dipolar in nature are "T Class Reactions"and they go through an

excited charge transfer complex which then couples to the corresponding

dipolar species. This dipole then closes to a four membered ring.

The formation of the vinyl ether-PhTD intermediate 46 by this pathway

is shown below.












The other possibility is an electrophilic attack of the electron

poor PhTD on the electron rich olefin in which no complex is required

to arrive at 46,i.e.,

0 R
__/ CH- 0 R
CH

N N- N-

Ph Ph









The first observation that is consistent with the postulated

1,4-dipole is the non-cyclic structure of the DVE--PhTD copolymer. A

diradical intermediate would have been expected to cyclize. However,

cyclization of the 1,4-dipole 46 would be highly unlikely since vinyl

ethers are known to be resistant to anionic attack.

Copolymerizations of the two vinyl ethers with PhTD were found

to be insensitive to a free radical inhibitor and a free radical

initiator. The free radical initiator azobisisobutyronitrile (AIBN)

had no effect on the molecular weight of the EVE copolymers (Table 1,

exp. 11). The copolymer from the DVE case showed some increase in

molecular weight, which some random coupling of pendant vinyl groups

could easily explain (Table 2, exp. 3). The known free radical

inhibitor, m-dinitrobenzene, had no effect on the copolymerization

of DVE (Table 2, exp. 6).

An attempt to free radically copolymerize DVE and PhTD at -45C

by photolytic decomposition of benzoyl peroxide only resulted in a

product identical to the ambient copolymerizations. Since the conversion

was extremely low, the product was probably the result of a slow thermal

reaction, because at the same temperature the same product was obtained

without benzoyl peroxide.

In an attempt to exclude moisture from the system, a copolymer-

ization of DVE and PhTD was effected under more rigorous conditions

than the normal trials. It was felt that since water would terminate

the dipolar step-growing chain that the elimination of moisture would

lead to a higher molecular weight copolymer. The dry conditions

included flame drying of glassware, predrying of monomers and transfer-

ing monomers and solvents in an inert and dry atmosphere. Although










TABLE 1. COPOLYMERIZATIONS OF EVE AND PhTD


Exp. Reaction Conditions


No. Solvent Temp.
oC

1 CH2C12 25


2 CH2C2 25


3 CH2C12 25


4 CH2C12 25

5 CI2C12 25

6 CH2C12 25

7 CH2C12 25


8 C CH2C12 60
9d

10 CH2C12 60


11e CH2C12 60


Time
(hr.)

0.5


0.03


0.25


1.0

4.0

12.0

24.0


24.0



24.0


24.0


Product and
conversion


87.5
1:1 copolymer

52.0
1:1 copolymer

75.7
1:1 copolymer







77.0
1:1 copolymer





77.4
1:1 copolymer

78.2
1:1 copolymer


Sa IR
n 1610 cm.


1660 s


410


670 s


1175 s

1340 s

1260 m

437











1 (continued).


Exp. Reaction Conditions Product and
No. Solvent Temp. Time Conversion
"C (hr.)

12 DMF 25 0.5 50.3
1:1 copolymer

13 THF 25 0.5 85.6
1:1 copolymer

14 THF 25 0.5 67.0
1:1 copolymer

15 CH2Cl2 60 118 71.5
1:1 copolymer

16 CH2C12 60 166 77.5
1:1 copolymer

17 CH2Cl2 60 211 76.2
1:1 copolymer


aVPO-acetate solution.
b
s, (strong); m, (medium); w, (weak); -, (not present).

CSample 1 dissolved and heated.

Sample 1 hydrogenated.

0.5 wt. % AIBN added.

10 mol. % NaPh4B added.


a
n


3900


940


2040


923


1120


970


TABLE~


IRb

1610 cm.


s


s


s


w


w


w










TABLE 2. COPOLYMERIZATIONS OF DVE AND PhTD

Exp. Reaction Conditions Product and a
No. Solvent Temp. Time Conversion n
C (hr.) 1610


1 CH2C12 25 0.5 77.5 450 w
1:1 copolymer

2 CH2C12 60 24 77.8 860 s
1:1 copolymer

3c CH2Cl 60 24 80.8 1590 s
1:1 copolymer

4 CH2C12 60 120 84.5 3130 s
1:1 copolymer

5d CH2CI2 60 24 86.0 2540
1:1 copolymer

6e CH2C12 60 24 65.8 2130 s
1:1 copolymer

7 CH2C12 60 120 85.8 2760 s
1:1 copolyner

8 CH2C2 25 22 85.7 w
1:1 copolymer
and adduct

9 Dioxane 60 24 66.4 1330 s
1:1 copolymer


IRb-
(cm. )
1640

m


m m


m m


m m












Exp. Reaction Conditions
No. Solvent Temp. Time
C (hr.)


DMF

DMF

CH3CN

CH3CN


24

24

24

0.5


TABLE 2 (continued).

Product and
Conversion



31.2

19.4

80.0

73.8


Ta IR
n (cm. )
1610 1640 860


VPO-acetate solution.
b
s, (strong); m, (medium); w, (weak); -, (not present).

C0.5 wt. % AIBN added.

Dry conditions.

el m-dinitrobenzene added.

Polymer 6 hydrogenated.









a higher molecular weight material was obtained than in the normal

trials, a control in which the glassware was not treated yielded even

higher molecular weights (Table 2, exp. 7 vs. exp. 5).

Szwarc41 has discussed in great detail the effect of trace amounts

of water on ionic polymerizations and the conditions needed to conduct

polymerizations in the absence of water and other impurities. Since

the purification procedures needed for such experiments required

special techniques and equipment, this approach was abandoned.

Surprisingly, the EVE-PhTD copolymerization conducted at 60C

resulted in a lower molecular weight product than in the room tempera-

ture trials. The 1610 cm.-1 band in the infrared spectrum of the

copolymer was absent, although the nmr spectrum was the same. The

elemental analysis remained consistent with a 1:1 copolymer. The room

temperature copolymerization was repeated for a 24 hour period and a

molecular weight of 430 was obtained compared to 2440 for a thirty

minute polymerization time. The 1610 cm.- infrared band was absent

in the product from the 24 hour run. A study of molecular weight

versus time was conducted for the room temperature copolymerization

and the results are shown in Fig. 5. A decrease in intensity of

the 1610 cm.-1 band paralleled the decrease in molecular weight.

Table 1 gives the molecular weight versus time in tabular form. Co-

polymerizations conducted at 600C for extended times showed a rebuild-

ing of the chain length (Table 1, exps. 15, 16 and 17).

These results can easily be accommodated by the proposed copolymer-

ization mechanism. The decrease in molecular weight is believed to

result from a depolymerization back to the 1,4-dipole structure and

then recombination through both nitrogen to give structure 36,















1 20-

12000

Mn
800-







200Li


2 4 6 12 22 24
REACTION TIME (HOURS)
Figure 5. Plot of Mn versus reaction time for EVE-PhTD in CH2Cl2 at 25C.









possibly a more stable structure. The DVE copolymer once formed was

observed to be thermally stable at 60"C as noted by no decrease in

molecular weight or decrease in the intensity of the 1610 cm.-1 absorb-

ance. Since the activation energy to reformation of the vinyloxy 1,4-

dipole would be expected to be higher than the ethyloxy because of the

difference in stability of the positive center, this result is also

consistent with the polymerization mechanism.

It is generally thought that dipolar reactions should show pro-

nounced solvent effects. The results of a solvent study of the reaction

rate are shown in Table 3. This study was conducted by observing the

disappearance of the band in the visible spectrum of the PhTD. No

pronounced rate differences were observed in going from the fairly

non-polar solvent benzene to the strongly polar solvents dimethylform-

amide and acetonitrile. There was a distinctive rate difference between

EVE and DVE. This was probably another manifestation of the difference

in the stability of the positive center of the dipole.

Gompper42 has recently reviewed cycloaddition reactions involving

polar intermediates. He cites two cases in which significant solvent

effects may not accompany such reactions. The first case involves

reactants that are highly polar and thus experience significant solvation

effects to effectively negate the solvation of the intermediate. The

second case involves a system where the energies of activation of the

first step and the second step are nearly the same and a change in

solvent changes the rate determining step, but not necessarily the

overall reaction rate.

Since both monomers are highly polar molecules, it is reasonable

that they could experience enough ground state solvation to effectively

cause the solvation of the intermediate to be undetectable.








One criterion which can conclusively demonstrate the presence of

a dipolar intermediate is the interception of this intermediate before

cycloproduct formation.4 When EVE and PhTD were reacted at room

temperature in acetone 3-oxa-2,2-dimethyl--4-ethoxy-8-phenyl-1,6,8-

triazabicyclo[4.3.0]-nona-7,9-dione 49,was formed in 42% yield. Along

with this product was formed a copolymer which from the nmr spectrum

appeared to have about 12% acetone incorporated.

This result is believed to be conclusive evidence for the existence

for the 1,4-dipole since the product arises from the interception of

the 1,4-dipole with the weakly dipolarophilic acetone. Apparently some

/OCI2CH3
2OC 2CH3 CH--0
CH


CH2 OC N 3-A CH3
N- CH --- \
3 0= < o
0-( ^N
N Ph
Ph H OCH C 49
12 2 3


o -N CH3
N N 3


Ph
terpolymer
and/or

/CH-O-CH2CH3
C2 0-
N-N- CCH3
S'C3

N
Ph

of the intercepted dipole did not close to the six membered adduct but

proceeded to link intermolecularly with other similar segments or with

other 1,4-dipoles to form the copolymcr containing about 12% acetone.









TABLE 3. FIRST ORDER RATE CONSTANTS IN PhTD AT 25C


A. Ethyl Vinyl Ether-PhTDa

Solvent k(sec)-l (D)

Acetone 5.36 x 10-2 20.7
-2
Dimethylformamide 6.02 x 10- 37.6
-2
Dioxane 6.83 x 10- 2.2

Acetonitrile 2.22 x J0-1 37.5

Methylene chloride 6.04 x 10-1 9.1
-l
Benzene 2.85 x 10-1 2.3


B. Divinyl Ether-PhTDa
-3
Dioxane 3.05 x 10-3 2.2

Acetone 1.13 x 10-2 20.7

Methylene chloride 4.20 x 10-1 9.1


al0:1 vinyl ether to PhTD





The infrared spectrum of 49, which is a new 1,3,4-tetrahydrooxa-
-l
diazine ring structure, showed strong absorbances at 2980-2880 cm.-

(saturated carbon hydrogen), 1770 and 1710 cm.-I (double carbonyl) and
-i
strong bands in the 1200-1000 cm.1 region due to the acetal linkage.

The nmr spectrum (Fig. 6) gave resonance signals at 67.40 multiplee,

aromatic hydrogens, 5), 65.02 (quartet, hydrogen on acetal carbon, 1),

63.73 multiplee, methylene hydrogens, 4), 6.1.85 (two equivalent

singlets, nonequivalent methyl hydrogen from incorporated acetone, 6)

and 61.25 (triplet, methyl hydrogens from ether, 3). The elemental

analysis agreed with the calculated value.










































8.0 7.0 6.0 5.0 4.0 3.0 2.0. 1.0

PPM (6).

Figure 6. Nmr spectrum of 3-oxa-2,2-dimethyl-4-ethoxv-8-phenyl-l,6,8-triazabicyclo[4.3.0]nona-7,9-dione.








In previous studies42,43,44 of the 1,4-dipoles, many different

reactive dipolarophiles have been utilized to intercept the dipolar

intermediates, i.e., isocyanates, acetylene dicarboxylate esters and

ketenes, among many others. However, apparently only one case has

been reported of a ketone performing this function and this involved

the reaction of perhaloacetones with cyanamides to form 1,3,5-oxa-
,. 45
diazines.




CH3 CF CF3 01 /CH3
1N-CEN + = 0 --- CF3 C-NH
CH CF3 N3 3


CH3 CH



3N-CN possible intermediate CF3 CC3

C/ C
CH3 C_ NCH3 + CH
SN-C=:N-C--N,
CH CH CH N 3
3 3 3



To investigate the scope of this novel interception reaction,

both the vinyl ether and the ketone solvent were varied. When isobutyl

vinyl ether was substituted for ethyl vinyl ether 3-oxa-2,2-dimethyl-

4-isobutoxy-8-phenyl-l,6,8-triazabicyclo[4.3.0]nona-7,9-dione, 50, was

formed in 47% yield. The infrared spectrum was practically identical

to that of 49 with only minor differences noted in the C-H stretching

frequencies and in the fingerprint region of the spectrum. The nmr

spectrum was similar to 49 except a doublet for the methyl groups of

the isobutyl group was present at 60.95 (6), and the multiplet due








to the methylene protons was less complex because of the isobuty]

group.




H2CH(CH3)2 OCH CH3 CHiCH
9 1 23 0 2
C CH--0 3H-
H2 CH CH CI2 C 3
Nh'N o )N-N 3
0 N =O 0= N 0 O < 00
Ph Ph
Ph

50 51 52

Changing the ketone solvent -from acetone to cyclohexanone

resulted in formation of 3-oxa-2-spirocyclohexyl-4-ethoxy-8-phenyl-

1,6,8-triazabicyclo[4.3.0]nona-7,9-dione 51 in 12% yield. Apparently

the low yield resulted from the more complicated procedure for product

isolation. The infrared spectrum appeared practically identical to

49 and 50. The nmr spectrum differed from that of 49 in that the

nonequivalent methyl resonances at 61.70 and 61.85 were replaced by

a broad multiple resonance from 61.50-62.80 (10) from the cyclohexyl

protons.

Divinyl ether, PhTD and acetone resulted in a small amount of the

tetrahydrooxadiazine 52 and a trace of 1,2-diazetidine 31b. Both were

identified by nmr with the oxadiazine spectrum resembling 49, 50 and 51,

while the 1,2-diazetidine resonances were identical to those of the

room temperature product of DVE-PhTD in methylene chloride 31b.

The mass spectral fragmentation patterns offered strong corrobora-

tive evidence for the proposed new 1,3,4-tetrahydrooxadiazine ring

structures. The fragmentation patterns were very similar to known









cyclic acetal fragmentations.6 They were different in that the

molecular ion appeared. This could be due to the unique structure

in which one ether linkage was inside the ring and the other was

outside. Schemp I shows the fragmentation pattern for 49. The

molecular ion m/e 305 (1%) is believed to fragment by two pathways,

a and b.


Scheme I

OCH2CH

b CH -0
\ C 3 a

C- .CH C / N 3 0

23 0 0 -CH3CC
N
Ph
m/e305 (M+)
SC 60
CH2
-\2
S-co \
O-- ----- 0
= -0 N 0
h Ph
el90 m/e218


4-
CH =0CH2 CH3
CH2
\2
N--N
O=< )=0 m/c247
N base peak
Ph p

-CH= CH2 /0
/ 'H
CH
c\2
-II0 N N-
0 Ph

m/e219


Pathway "a" involves loss of acetone to form m/e 247, the base

ion. This is followed by the loss of ethylene to m/e 219 (8%) which

then appears to rearrange and lose a hydrogen atom to m/e 218 (22%).

Ion m/e 190 (59%) subsequently follows by loss of carbon monoxide.

Pathway "b" involves loss of the ethoxy radical to form ion m/e 260

(7%), a general cracking course for both acetals46 and glucosides.47

Comparison of the fragmentation of 50 and 51 (Schemes II and III


m/e260


CH2

N-


m/
m/






42


Scheme II


GCR CH(CH )

CH3 H>0 C
/c H \ + 32
CH b CH2 /'-CH a
3 -- -- N ----

-0 -6CH2oCH(CH3)2 o 0- \ -C3 31
CN 3C
h
m/e333 (Mi+)

C--CE0
CH, 2 H
2 -H -CO NN


N N
bP Ph

m/el90 m/e218
base peak


CH=0CH2CH(CH3)2

CH2
\2
N-N

N
Ph
m/e275 -CHCH(CH )
2\ H 3 2
OH



\2

Ph

m/e219


Scheme III


Uc>


N-N -0CH2CH3


Ph
m/e300




CH
C2 ,H
2(--N -CO


Ph
m/el90


OCH2CH3

CH2 /J

N N -0

Ph )
m/e345 (M+)


+
CEO
C2 "H
N- -H.

0< -0

Ph
m/e218


11-DCH2 CH3
CH2
N "



Ph
m/e247
base peak
-CH- CH2

OH

CH
\2
N -N



Ph
m/e219


ci/e260









respectively) with that of 49 shows similar ions resulting from the

same double fragmentation pathway.

From these results (summarized in Table 4) it appears that the

reactivity of the 1,4-dipole is quite sensitive to stabilization of

its positive center. The high yields of oxadiazine when the carbonium

ion stabilizing substituents, ethoxy and isobutoxy, are present and

the low yield with vinyloxy are believed to mean that the intermediate

has more pronounced dipolar character when its positive center is

stabilized and hence can add across the weak dipolarophilic alkyl

ketones. This is the same reasoning used to explain the earlier

copolymerization results. In agreement with the above observations

is the PhTD-indene30 reaction in which no oxadiazine was reported even

though the reaction was performed in acetone.


TABLE 4. SUIIARY OF INTERCEPTION REACTION RESULTS


Vinyl Ether Ketone % Yield M.P.

CH2=CH-O-CH2CH3 Acetone 42% 149-151C

CH2=CH-OCH2CH3 Cyclohexanone 12%a 170-171C

CH
I 3
CH2=CH-O-CH2-C-C3 Acetone 47% 125-126'C

b
CH2=CH-0-CH=CH2 Acetone trace

(a) Yield lower possibly because of difficulty in work up.

(b) Identified from nmr. Also some 1,2-diazetidine formed.


By employing this unique property of these 1,4-dipoles, it was

felt that information on the degradation of the EVE-PhTD copolymer

could be obtained. When a high molecular weight sample of this









copolymer was refluxed in acetone, the usual decrease in molecular

weight was observed along with a trace amount of oxadiazine 49. This

was believed to result from degradation back to the initial 1,4-dipole

which in turn was trapped by the acetone. This is interpreted to mean

that, at least in part, the degradation is a reverse reaction of the

original polymer formation.

Soluble salts are generally known to exhibit significant effects

in either anionic or cationic polymerizations. It was felt that the

ions of a soluble salt would effectively "tie up" some of the "living

ends" of the propagating dipole and prevent their intermolecular cou-

pling and hence lower the molecular weight. Mhen the EVE-PhTD copoly-

merization was effected in tetrahydrofuran solution in the presence of

10 mole % of sodium tetraphenylboron, a significant change in the mol-

ecular weight was observed. A control in tetrahydrofuran yielded an

average molecular weight of. 2040 versus 940 for the sample containing

the salt.

Another mechanistic pathway which merits consideration is that of

a ring opening polymerization resulting from attack of the zwitterionic

intermediate on an unopened 1,2-diazetidine. Although the data do

not allow this mechanism to be disregarded, especially in the DVE case,

the observation of molecular weight increase with time for both the DVE

and EVE cases is not consistent with such a propagation mechanism.

This evidence is particularly persuading for the EVE-PhTD copolymeri-

zations because of two observations. The first observation resulted

from an experiment conducted in an nmr tube. This experiment showed

that when the reactants were mixed and inserted directly into the nmr

cavity only copolymer was observed. The second observation was that









even though all the PhTD was consumed after 10 minutes in the PhTD-

EVE copolymerization, the molecular weight increased over a 0.5 hour

time period (Fig. 5). Since no adduct was present as indicated by the

first experiment, the molecular weight growth is attributed to dipolar

coupling. Wilson and Beaman48 have recently observed a system in which

the molecular weight increased after an addition polymerization was

complete and attributed the phenomenon to a coupling of residual poly-

meric dipoles.

Another polymerization in which some dipolar coupling was postu-

lated was the catalytically initiated polymerization of 1,1,3,3-tetra-
49
methyl-1,3-disilacyclobutane, 53.
C11
{'3
C Si-CH3


CH3
53

The vinyl ether-PhTD copolymerizations are believed to be the

first reported cases of a dipolar coupling being the sole propagation

mechanism.



Mechanism of termination

In all of the copolymerizations the highest molecular weights ob-

tained were only in the vicinity of 3000 (Tables 1 and 2). These low

molecular weights are thought to be a result of facile termination re-

actions. As was stated earlier, ionic polymerizations are readily sub-

ject to termination reactions by impurities such as water. At least

two other termination reactions could occur. The first would be an

intramolecular dipolar coupling to a macrocyclic structure and the










second is a type of disproportionation to an inactive species as

shown below. Another possible consideration is that the dipoles are




S TN-T-N H,- N v
2 + N
0 0= 0 ---)- CHZCH 0( .O0
R N 0
Ph R





so stabilized to result in a "living" structure. Unfortunately no

experimental evidence was obtained supporting any of the possible

termination reactions.



B. Copolymerization of 4-Phenyl-l,2,4-triazoline-3,5--dione with-

Other Monomers

Vinyl acetate and divinyl carbonate

To broaden the scope of the copolymerization and reaction character-

istics of PhTD, its reactivity was investigated with several other

olefinic systems. Vinyl acetate (VAC) and Divinyl carbonate (DVC)

were chosen for investigation because these monomers were expected to

be somewhat less reactive than the vinyl ethers.

VAC was observed to react with PhTD at room temperature, but at

a considerably slower rate than the vinyl ethers. The infrared spectrum
-4
of the product exhibited a medium intensity 1610 cm.- band. The nmr

spectrum gave broach resonances at 67.48, 64.32 and 62.16. Superimposed

over these resonances were sharp singlets. A reaction conducted at

60C in a sealed tube yielded as the major product an adduct which was
assigned structure 55, (foyl hyl)-2-acty-2,4-tiazoline-3,5-
assigned structure 53, l-Cfo-a-mylmeichyl)-2-acetyl-l,2 ,4-triazoline-3,5-










TABLE 5. COPOLYMERIZATIONS AND REACTIONS OF PhTD AND OTHER MONOMERS


Comonomer



Acrylonitrile
Acrylonitrile
Acrylonitrileb

Acrylonitrile
Divinyl sulfone
Divinyl sulfone
Divinyl sulfoneb


N-vinyl carbazole
N-vinyl carbazole
Vinyl acetate
Vinyl acetate
Vinyl acetate
Vinyl acetate
Divinyl carbonate
Divinyl carbonate
Divinyl carbonate


avPO-acetone solution
b0.5 wt.%AIBN added
CCalculated from GPC


Solvent Conditions
Temp. Time


CH2C12
CH2Cl2
CH2C12




CH2C12

CH2C12

CH2C12





CH2C12
acetone
CH Cl
CH 2 Cl2


CH2C12
CH2C12
CH2C12
CH2 Cl2


--a
Yield M
n


(hr.)
42
144
24


15.1
63.0
31.8


33.0
59.3
33.5
29.0


86.0


57.3
1.2
78.3


44.9
0.36


21


60 24 73.5


Product


-- PhTD oligomeric species
-- PhTD oligomeric species
-- Possibly some copolymer
from elemental analysis


PhTD oligomeric species
PhTD oligomeric species
No sulfur present from
elemental analysis
,000c 1:1 copolymer
-- 1:1 copolymer
-- Copolymer and 55
-- Not identified

370 Mostly 55
-- Mostly 55
-- 2:1 copolymer
Not identified

1240 2:1 copolymer









done. This compound apparently arose from an internal trap of the

intermediate 1,4-dipole 54.




+ 0
CIE 0 0 C-H

C 2 / CH3 -C C-CH
N-N N-N
0:= ( 0 0M =0

Ph Ph

54 55

The infrared spectrum of 55 showed two weak bands characteristic

of an aldehyde carbon hydrogen stretch at 2860 cm.-1 and 2750 cm.-1 A

double carbonyl absorbance at 1800 cm.- and 1730 cm.- was also char-

acteristic of the urazole type structure. The nmr spectrum (Fig. 7)

gave resonance signals at 69.56 (singlet, aldehyde hydrogen, 1), 67.50

(singlet, aromatic hydrogens, 5), 64.80 (singlet, methylene hydrogens,

2) and 62.60 (singlet, methyl hydrogens, 3). The mass spectrum yielded

the correct parent peak at m/e 261 and the elemental analysis agreed

with the 1:1 structure.
-l
The broad nmr resonances and the 1610 cm.- infrared band were

probably indicative of the formation of some copolymer in the room

temperature reaction. The small amount of polymeric material is be-

lieved to be indicative of the low activation energy of the intramolec-

ular six menbered transition state rearrangement.

An attempt to trap the initial dipole before the intramolecular

reaction occurred was made utilizing a large excess of phenyl isocy-

anate as the dipolarophile. Only 55 was isolated. The reaction was

also performed in acetone so that the initial dipole could be trapped


































~i --------------------- i --- ---i-- ------


9.0 8.0 7.0 6.0 5.0 4.0 3.0
PPe sec
Figure 7. Nmr spectrum of 1-(formylmethyl)-2-acetyl- ,2,4-triazoline-3,5-dione.









to form an oxadiazine as was accomplished in the vinyl ethers. The ma-

jority of the reaction was 55. A few milligrams of material were iso-

lated which gave an nmr spectrum with resonance signals at 66.30 (mul-

tiplet), 63.75 doublett) and 61.72 (singlet). The spectrum was

complicated by the presence of 55. The above resonances appeared in

the ratio of 1:2:6. This could be evidence for the formation of a

small amount of the oxadiazine 56.


0-CCH3
CH--0

\2 /CH3
N--N


Ph

56

DVC was found to react slowly at room temperature and at 60C to

give a material shown by elemental analysis to be a 2:1 structure. A

strong 1610 cm.-1 band was observed in the infrared spectrum and the

nmr spectrum gave broad resonances at 67.38 (singlet, broad, 6) and

65.31-63.31 multiplee, broad, 1). A molecular weight of 1220 was ob-

tained for the 6000 polymerization. No observations were indicative

of the occurrence of a double internal trapping reaction analogous to

the vinyl acetate reaction.



Divinyl sulfone and acrylonitrile

The normally electron poor olefins divinyl sulfone (DVS02) and

acrylonitrile CAN) were chosen for investigation to see if they would

act as electron donors with PhTD.

DVS02 appeared to give some reaction since more solid was obtained









in an attempted copolymerization at 600C than was obtained with a con-

trol of PhTD. No sulfone absorbances were noted in the infrared spec-

trum and an elemental analysis only yielded a trace of sulfur.

AN showed no indication of reaction at room temperature or at

600C for six days. At 60C, with a free radical initiator present,

some product appeared to result. An analysis of the infrared spectrum
-l
showed a new medium intensity 1610 cm.- band. An elemental analysis

yielded a higher nitrogen content than would result from a reaction

only involving PhTD. No structure assignments were feasible.



N-vinyl carbazole

N-vinyl carbazole CNVC) was observed to spontaneously copolymerize

at 25C to yield an 86% yield of a 1:1 copolymer. The composition was

established by elemental analysis. Only a weak-medium 1610 cm.-I ab-

sorbance was observed in the infrared spectrum. The nmr spectrum yield-

ed two large broad resonances centered at 68.50 and 65.80. Because of

the weak 1610 cm.-1 absorbance the polymer structure was thought to

be 57.






N-N---- CH --CH


N
h -n



Insolubility of the polymer in acetone precluded the usual vapor

pressure osmometer molecular weight determination. However, calculation

of the number average molecular weight from gel permeation chromatog-










raphy, calibrated with polystyrene, gave a value of 21,000. The

weight average was calculated to be 54,000 and the molecular weight

distribution (M /M ) was 2.57. In making the calculations a very
w n
dangerous assumption was necessary. It was assumed that polystyrene

and the copolymer had similar coil dimensions in the solvent used

for the determination. Although this assumption appeared to be valid

in the DVE-PhTD copolymer, it was not necessarily valid in this case.

The molecular weight obtained in this system is significantly higher

than in the vinyl ether copolymers. No reasons are apparent for the

change in structure and the change in molecular weight of the NVC

system.

When the polymerization was conducted in acetone, a similar

polymeric structure was obtained. Only a minute amount, if any, of

the corresponding oxadiazine was observed. An nmr spectrum from

a small amount of apparently non-polymeric material showed multiplets

at 64.50 from methylene hydrogens and 62.20 from methyl hydrogens.

Not enough material was isolated to identify and characterize this

product. The failure of acetone to trap the probable intermediate

dipole is probably due to the large steric effect of the vinyl

carbazole moiety.

Stille and Aoki 50 have initiated the homopolymerization of

electron donors by addition of catalytic amounts of strong electron

acceptors. The homopolymerizations are proposed to be initiated by

an excited ionic s'ate of a charge transfer complex. Since NVC is

known to readily homopolymerizc, it was thought that the addition of

a small amount of PhTD to a solution of NVC could possibly trigger a

cationic homopolymerization of the NVC in which the initiation would










be effected by the positive end of the dipole. An attempted polymer-

ization was unsuccessful.



C. Reactions and Attempted Homopolymerizations of 4-Phenyl-1,2,4-

triazoline-3,5-dione

4-substituted-l,2,4-triazoline-3,5-diones have the potential to

yield polymers possessing a nitrogen backbone if an initiation could

be effected through the nitrogen to nitrogen double bond. This promise

made the investigation of the behavior of the triazoline diones in

the presence of radical and ionic initiating species an attractive

proposal.

PhTD has been described51 as decomposing instantly in basic

solution, while in the presence of acid, water or alcohol the rate

of decomposition was noted to be slower. Even in the presence of

light or in solution at room temperature some decomposition was

reported. No one has studied the decomposition products and their

mechanisms of formation.

The thermal decomposition of PhTD at 60OC in a scaled tube was

studied to determine if there was any appreciable decomposition that

could compete with the copolynerizations. During the course of the

reaction the color remained red and a few milligrams of a white

crystalline solid formed in the bottom of the tube. Precipitation

of the red solution yielded a small amount of tan-w:hite solid 59.

The white cry-talline solid did not melt when the temperature

was raised to 300"C. The infrared spectrum gave no saturated carbon-
-I
hydrogen stretching absorbances and gave a double carbonyl at 1785 cm.

and 1755 cm.-1 The mass spectrum yielded a parent peak at m/e 322
and 1755 cm. The mass spectrum yielded a parent peak at ale 322










and a base peak at m/e 119 (phenyl isocyanate ion). Structure 58,

3,7-diphenyl-1,5-diazabicyclo[3.3.0]octa-2,4,6,8-tetraone, was assigned

from this data. An elemental analysis perfectly agreed with the

calculated value.

0 0


Ph-N N-Ph


0 0

58

Two reports of 58 were found in the literature. Snyder52 reported

the formation of a bright orange solid, melting point 203-2040C,

during a refluxing reaction of PhTD. In this case PhTD was generated

by oxidation with t-butyl hypochlorite in acetone. The only structure

proof presented was infrared data which included a double carbonyl
53
and an aromatic absorbance. Koch and Fahr reported the formation

of 58 in a thermal reaction of PhTD in an apolar solvent. No structure

proof or physical characteristics were presented.

The tan-white solid 59 isolated by precipitation into hexane

had 3500 cm.-1 and 1715 cm.-1 absorbances in the infrared spectrum.

The nmr spectrum gave broad resonances at 67.50 (broad multiple, 6)

and 64.48 (broad multiple, 1). The number average molecular weight

from vapor pressure osmometry was found to be 600. The elemental

analysis did not correspond to any regular structure resulting from

a homopolymerization of PhTD.

When PhTD was heated in a sealed tube in methylene chloride

solution in the presence. of azobisisobutyronitrile, results identical

to reaction without the free radical initiator were obtained. An










attempt to initiate a free radical homopolymerization of PhTD by

photolysis of benzoyl peroxide at -45C only resulted in a small

amount of the oligomeric PhTD decomposition product 59.

In attempting to explain the mechanistic pathway for the thermal

decompositiolof PhTD to 59, the first reaction is probably the forma-

tion of phenyl isocyanate. Phenyl isocyanate could then in turn


heat

0 0 Ph-N C= 0
-N
N 2
Ph -CO


react with water to form aniline. When a catalytic amount of aniline

H 0 -CO
Ph-N=C=0 + H20 -> [Ph-N-c-0-H] -- PhNH2


was added to a methylene chloride solution of PhTD, some of the

oligomeric decomposition product 59 resulted.

Another related experiment was to see what products were formed

in the decomposition of PhTD by water, since PhTD had already been

shown to readily decompose in water.5 When PhTD, in dioxane solution,

was added to water a vigorous reaction insued and a large amount of

oligoneric product 59 was obtained. A small amount of N,N'-diphenyl

urea was also obtained. One of the products from the reaction is

most assuredly phenyl isocyanate which then goes to aniline and then

reacts with more phenyl isocyanate to yield the diphenyl urea.

Since aniline served as a catalyst for for:ration of the oligomeric

product 59, an investigation using other nucleophilic species was

initiated in hopes of effecting the formation of high polymer.

Triethylamine was used as the initiator and a similar product 59









was obtained. Surprisingly approximately 10% of 58 was

isolated.

The strong nucleophilic reagent, sodium cyanide in dimethylforma-

mide was then used as the initiator and a large yield 70-80 per cent

of the tetraone 58 was obtained. A small amount of 59 was also obtained.

The rationalization of the formation of 58 from attack of a

nucleophile on PhTD presents an interesting mechanistic problem that

was not covered in the scope of this research. However, the following

explanation is put forth as a possible mechanistic pathway of the

unusual reaction.
54
Kealy54 has observed the formation of 61 from the decomposition

of diazoquinone 60. He did not propose a mechanism for the formation

of 61, but only referred to earlier work on the decomposition of azo

compounds by radical pathways. For example, Leffler and Bond5 have

studied the radical decomposition of dibenzoyl diimide 62 where 63 is

one radical intermediate.
0 0
PhC-N=N-CPh 62
0 0 0


IN 0
t 2 PhC.
0 0 0
63

60 61

For the diazoquinone, a probable diradical intermediate would

be 64 which could couple with an intact molecule of diazoquinone 60

to yield 61.

If such a diradical. intermediate 65 was involved in the formation

of the tetraone 58 from a nucleophilic catalyzed reaction of PhTD









0



0'
0


+ 60


64

an unusual carbenoid mechanism could be involved as shown below. No

proof has been gathered in support of this mechanism, although in the

studies conducted on the radical decomposition of 6255 much higher

rates of decomposition were observed in strongly nucleophilic solvents

like aniline. The reason for this could be a nucleophilic catalyzed

reaction as was discussed for the formation of 58.


TABLE 6. SUMMARY OF CATALYZED PhTD

Conditions


90C, vacuum

Most electron poor comonomers

CH2Cl2, 600C, 70 hrs., sealed tube

CH2C12, 60C, 24 hrs., sealed tube

water, dioxane, 25'C, 1 hr.


aniline, CH2C12, 25C

triethyl amine, CH2C12, 25'C, 1 hr.

sodium cyanide, dimethylformamide
2.5 hrs., 25"C


REACTIONS

Products


(n = 1000)

(small amounts)

(27%), 58 (1%)

(10.4%), 58 (trace)

(61.5%, diphenyl
urea, (7.8%)

(22.0%) (Mn = 470)

(24.5%), 58 (9.5%)

(small amount)
(approximately 80.0%)


A summary of all the reactions and decompositions of PhTD is

presented in Table 6.

While this research was being conducted, Stickler and Pirkle12

reported the first synthesis of a nitrogen backboned polymer. Their


Exp.
No.










o=< )o +- -o J \ -

N I N N + N N
N N +NI
Ph Ph Ph







Ph


65



success resulted from a visible light irradiation of 4-n-butyl-l,2,4-

triazoline-3,5-dione.



D. Diels Alder Polymers

Synthesis of 4,4'-(4,4'-diphenylmethylene)-bis-l,2,4-triazoline-3,5-

dione

Since the diisocyanate 66, 4,4'-diphenylmethane diisocyanate,was

readily available from commercial sources, the bis triazoline dione

selected as a target for synthesis was 69, 4,4'-(4,4'-diphenylmethyleno)-

bis-1,2,4-triazoline-3,5-dione. The synthesis of the diurethane

precursor 67 was accomplished in a near quantitative yield by the

addition of two moles of ethyl carbazate to 66. The infrared .spectrum

yielded strong N-H stretches at 3380 cm. and 3305 cm.-. Strong

carbonyl absorbances vere observed at 1735 cm.- and 1685 cm.- The

nmr spectrum gave resonances at 68.77 (singlet, hydrogens on nitrogen,

2), 67.91 (singlet, hydrogens on nitrogen, 2), 67.20 (A2B2 quartet,

aromatic hydrogens, 8), 64.05 (quartet, methylene hydrogens, 4),









63.79 (singlet, methylene hydrogens, 2) and 61.19 (triplet, methyl hy-

drogens, 6.). The product gave the correct elemental analysis.




CH -N=C-0 24- 2H2NNHCOCH2CH3- CHH0 --NHCNHNHCOCII2CH3


66 67

67 was quantitatively cyclized to the bis urazole 68 with 4M po-

tassium hydroxide. The infrared spectrum yielded a broad band front



67 4M1 KOH CH2 H
11 H 1 2
68 0
-1 -i
3320 cm. to 2760 cm., a characteristic noted in the simple urazoles,

and gave a double carbonyl absorbance at 1765 cm.- and 1680 cm.- The

nmr spectrum gave resonance signals at 67.80-67.20 (broad with a sharp

spike at 67.38, aromatic hydrogens and hydrogens on nitrogen, 12) and

64.03 (singlet, methylene hydrogens, 2). The elemental analysis

agreed with the calculated value.

The oxidation of 68 to the bis triazoline dione 69 was accomplished

in approximately 80% yield using dinitrogen tetroxide in the same man-

ner as employed by Stickler and Pirklel2 in the synthesis o[ the simple

triazoline diones. The infrared spectrum showed an absence of any N-H

stretching frequencies and yielded the characteristic double carbonyl

at 1790 cm.-1 and 1760 cm.-1 The nmr spectrum yielded, surprisingly,

only two singlets, on, at 67.48 (aromatic hydrogens, 8) and 64.18

(methylene hydrogens, 2).

69 reacted readily -with reactive dienes. The reaction with 2,3-

dimethyi-l,3-butadiene yielded 70. 70 was identified by its nmr spec-











II 1 0 Ci
7 CH CH 3
C2 NC i 3 -3 CH-2 N
2 0 0 3
69 70

trum which showed resonance signals at 67.33 multiplee, broad, aromatic

hydrogens, 8), 64.00 (broad singlet, allylic next to nitrogen and benzy-

lic hydrogens, 10) and 61.75 (broad singlet, methyl allylic hydrogens,

12).



Diels Alder polymerization of styrene and 69

Cookson and coworkers51 have investigated the Diels Alder reactions

of triazoline diones and found that PhTD spontaneously reacted with

styrene to yield the double Diels Alder adduct 71. Maleic anhydride56

and ethyl azobisformate57 have been shown to react with styrene in a

Diels Alder fashion, but the final products in both cases were 72 and

73. These products resulted from an ene reaction after the first Diels

Alder reaction. Cookson's results meant that styrene, potentially,

would be an attractive bis diene to investigate with 69.

When styrene was reacted with 69 at room temperature in dimethyl-

formamnrde solution, the deep red initial color faded to a much lighter

red after two hours. After seven and one half hours, the red color,

characteristic of unreacted 69, persisted. The solution was divided

and the first half was precipitated into ether to yield a tannish,

highly electrostatic powder. The second half was in turn divided into

two portions and a discharge of the red color was noted after a few

minutes. Precipitation into ether yielded an identical polymer (in-













SH H-N-CO2CH2CH3
O22
H H -C02CH2CH3

0 N-CO2CHCHH
-0
0 dO2 CH2H3
0-
72 73
0
PhNN I I



Ph-N -I
S -0 ,
NN & N
71 0 0 75 0/ NPh









frared) as the portion precipitated while still red. The last portion

was heated to reflux and immediately it began to darken. It was pre-

cipitated into ether and a much darker solid resulted.

The repeat structure of the polymer was assigned to 74, which re-

sults from a Dicls Alder adduct which rearomatizes via an ene reaction

as 72 and 73. This is contrary to what was expected a priori. The

assignment was made from the infrared and nmr data and comparison to

the model compound 75.

When PhTD and styrene were reacted in methylene chloride at room

temperature 75 was formed rather than the reported Diels Alder adduct
-i
71. The infrared spectrum gave an N-H stretch at 3280 cm. and the

usual double carbonyls at 1765 cm. and 1720 cm. The nmr spectrum

(Fig. 8) gave resonance signals at 68.38 doublett, hydrogen on nitrogen,

1), 67.35 and 67.38 doublett and multiple respectively, aromatic

hydrogens, 4), 65.70 (triplet, benzyl hydrogen, adjacent to nitrogen,

1), and 64.22 multiplee, methylene hydrogens, 2). The elemental

analysis agreed with the 2:1 structure.

The polymer gave the double carbonyl in the infrared spectrum at

1780 cm. and 1715 cm.-. The N-H stretch was very weak. The nmr

spectrum (Fig. 9) showed resonances at 68.40 doublett, broad, hydrogen

on nitrogen, 1), 67.37 (singlet, broad, aromatic hydrogens, 12), 65.67

(singlet, broad, benzyl hydrogens adjacent to heteroatom, 1) and

64.50-63.80 (muitiplet, broad, two sets of methylene hydrogens, 4).

The polymer wis soluble in both dimethylformamide and dimethyl-

sulfoxide. The thermal decomposition was recorded using a Differential

Scanning Calorimeter and.was found to start at 3070C. An intrinsic

viscosity determined in direthylformamide at 280C was 0.12. Calculation




































I I I 1
8.0 7.0 6.0 5.0 4.0 3.0 2.0

PPM (6)
Figure 8. Nmr spectrum of the Diels Alder, ehe adduct of 4-phenyl-1,2,4-triazoline-3,5-dione and styrene.








































I I I I I I 1
9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0
PPM f s a

Figure 9. Nmr spectrum of the Diels Alder, ene polymer from styrene and bis triazoline diane.









from gel permeation chromatography showed a molecular weight distri-

bution of 3.34 with the weight average molecular weight, An = 36,000.

These values were calculated from a calibration with a polystyrene

standard, and again the assumption is made that the coil sizes are

similar for the two polymers.

An attempted polymerization of 69 using sodium cyanide in

dimethylformamide yielded a light brown polymeric material. The

synthesis of a polymer with structure 76 was the object of this exper-

iment. The infrared spectrum of this material was not similar to

the monomeric tetraone 58 so apparently the desired decomposition and

coupling reaction did not take place.















CHAPTER III

Triple Strand Polymer Model Compound Studies

A. Attempted Synthesis of Tetracyclo [4.4.0.1 '9.1 48] Dodecane and

Related Systems

Synthetic schemes

The synthetic pathway for the attempted synthesis of the cage

structure 18 is shown below in Scheme IV.

SCHEME IV


0
SI


o8
0
89


CH20R OH20R (1) ORCH O21s

JCH OR Y CHOR (2) C- COAs
2 0 -- Q2 2
77a,b 83a,b 24

R=a= -OCCH3
R=b= -H (1) catalytic hydrogenation
(2) MsCI


24 base


reduction 18


Scheme V is a proposed synthetic pathway to 25 which is the precur-

sor to 26, a simplified cage structure re-lated to 18.









SCHEME V
IC CHOR 0 0
< >2 O CH2OR (1) H O20Ms
+-2 (2) K

79a,b 0
89 0 8a,
R=a= -OCH3 25
R=- (1) catalytic hydrogenation
R=b= -H
(2) MsCI

base reduction
25 -- -------->- 26


Synthesis of dienes

The first step in Scheme IV required either 2,3-di(acetoxymethyl)-

1,3-butadiene or 2,3-di-(hydroxymethyl)-1,3-butadiene, 77a and 77b.

Both of these dienes had previously been synthesized by Bailey and

Sorenson.58 These authors prepared 77a by pyrolysis of 2,3-di-(acetoxy-

methyl)-l,4-diacetoxybutane, 81, at 480C. Although the reported


CH CH Br CH OCCH
NB0LS /- S2 A' / >'2 77a3
2 C\ fCHJ\ r CHCH2lC 0.1 mm.
CH!3 2 2 3
82 83 84



yield was 84%, this was based on the recovery of unreacted starting

material and the formation of a mono elimination product. Actually

the conversion to 77a was only 16%. It was felt that the method of
29
Butler and Ottenbrite29 used in the preparation of 2,3-di-(bromo-

methyl)-l,3-butadione would result in a more efficient preparation

of 77a.

The first precursor to the desired dines, 2,5-dihydro-3,4-

dimethylthiophene-l,l-dioxide or commonly referred to as dimethyl-










0 0
(CH3COCH2) 2CHC CH2OCCH3) 2
81
CH3 / I Br //- CHCHOCCH3
02S I NBS 02S As ICH3 -O- 02S- 79a
CH3CN
85 86 87


butadiene sulfone, 82, was prepared by the method of Frank and Seven59
29
in 90% yield. This was then brominated2 with N-bronosuccinimide in

38% yield to 83. Treatment of this dibromide with silver acetate in

acetonitrile resulted in a 73% yield (after recrystallization) of the

diacetoxy sulfone 84. The elemental analysis of this compound agreed

with the calculated and the infrared spectrum showed a strong carbonyl
-l
absorbance at 1720 cm.- for the ester group. The nmr spectrum yielded

resonances consistent with the structure and they appeared at 64.75

(singlet, broadened, allylic hydrogens adjacent to acetoxy, 4), 63.86

(singlet, broadened, allylic hydrogens adjacent to sulfone, 4), and

62.08 (singlet, methyl protons, 6).

Pyrolysis of 84 was accomplished smoothly at 200"C and 0.1 mm

pressure in 56.6% yield using a Hoskins furnace as the external heat

supply. The white solid diene was purified by recrystallization and

yielded the reported melting point.58 Saponification5 to 77b was

accomplished in 90% yield.

By using the same general procedure as used in the preparation of

84, the sulfone precursor, 87, to the acetoxymethyl diene 79a was

prepared in 74% yield. The bronmcmethyl sulfone 86 was prepared by

the method of Krug and Yen60 by bromination of isoprene sulfone 85

with N-bromosuccinimide. When 86 was reacted with silver acetate in








-l
acetonitrile 87 was formed as a yellow-brown oil.. It showed a 1735 cm.

ester carbonyl in the infrared spectrum and yielded the correct elemen-

tal analysis. The nmr spectrum exhibited resonance signals at 66.07

(singlet, broad, vinylic hydrogen, 1), 64.69 (singlet, broad, allylic

hydrogen next to acetoxy, 2), 63.81 (singlet, broad, allylic hydrogen

next to sulfone, 4) and 62.10 (singlet, methyl hydrogens, 3).

Pyrolysis of this oil was accomplished at 2000C at 0.5 mm. and an

84% yield of 79a was obtained. This was purified by distillation and

the infrared characteristics were identical to those reported by

Bailey and coworkers6 who had prepared 79a from the pyrolysis of 88.


9 0
CH COACH CH CHCH o0CH
CH 2 CCH3
0

88



Attempted Diels Alder reactions with p-benzoquinone

When the diacetoxymethyl diene 77a and the dihydroxymethyl diene

77b were reacted with p-benzoquinone, 89, the normal Diels Alder adducts

were not isolated. Reaction of 77a with 89 in acetic anhydride resulted

in the formation of the dehydrogenated adduct 90. The infrared spectrum
-i
of this reddish brown solid exhibited carbonyl absorbances at 1725 cm.-
-i
(ester) and 1655 cm.- (quinone). The nmr spectrum yielded resonances

at 66.75 (singlet, quinodial hydrogens, 2), 64.78 (singlet, allylic hy-

drogens adjacent to acetoxy, 4), 63.23 (singlet, doubly allylic hydro-

gens, 4) and 62.12 (singlet, methyl hydrogens, 6). A correct elemental

analysis was obtained. The same reaction carried out in benzene

yielded a crude oil possessing the same nmr resonances as 90 with








additional resonances at 66.77, 66.75, 64.64 and .62.43. The 63.23

resonance was broadened considerably. This was apparently a mixture of

unreacted quinone (66.77), 90 and the desired Diels Alder adduct 78a.

On addition of ethanol to the oil 90 was formed as a precipitate and no

indication of 78a was found in a spectroscopic analysis.

The reaction of 77a and 89 was then performed in refluxing chloro-

form and the progress of the reaction was followed by nmr spectroscopy.

Disappearance of resonances attributable to starting quinone and diene

was observed and the appearance of signals at 66.68 (singlet, quinodial

hydrogens, 2), 64.65 (singlet, allylic hydrogens adjacent to acetoxy,

4), 63.27 multiplee, broad, bridgehead hydrogens, 2) and 62.44 (multi-

plet, broad, allylic hydrogen, 4) was noted. After 135 hours a con-

version of 80% was calculated from the nmr spectrum. Removal of the

chloroform yielded a yellow oil. This was chromatographed on silica
-l
gel and a white solid resulted that showed a strong 3400 cm.- band
--l .
and a disappearance of the 1650 cm.- in the infrared spectrum. This

indicated that 78a had rearranged to the hydroquinone derivative 91.

The nmr spectrum gave resonances at 66.64 (singlet, aromatic hydrogens,

2), 64.48 (singlet, allylic hydrogens adjacent to acetoxy, 4), 63.47

(singlet, doubly allylic hydrogens, 4) and 62.88 (broad, hydroxyl

hydrogens). 0
I! CIt2R
CH2R

0 CHR CH2R


6 12 IR CE 2 R 90
2 CH 2 CUR
89 77a 0
R= -0CCl3 C 9 CH2R
U 91
H









The reaction of the dihydroxy diene 77b with 89 failed to pro-

duce the desired Diels Alder adduct as an isolable material also. In

refluxing chloroform a brownish solid formed whose nmr spectrum gave no

resonances that could be assigned to a Diels Alder adduct.

When the reaction was performed in tetrahydrofuran, a brownish-

yellow oil was obtained which was initially chloroform soluble, but

precipitated within a short time as a white solid. The absence of a

quinone carbonyl in the infrared spectrum and the absence of bridge-

head hydrogen resonances in the nmr spectrum was indicative that the

desired Diels Alder adduct 77b was not present. The presence of a

strong 1710 cm. absorbance in the infrared spectrum quite possibly may

be due to some double Diels Alder adduct 92. There was, however, no







HOH2C CH20H
0 0
11OH9 C .!y< CH OH CH OH


2 H 2 O 2

92 H 93


other indication of this. More likely, since the bridgehead protons did

not appear in the nmr spectrum, 93 was formed.

The Diels Alder adducts of 89 and both 2-bromomethyl-1,3-butadiene,

94, and 79a were not isolable under the reaction conditions employed.
60
94, the bromine substituted diene, reacted with 89 in acetic

anhydride to give a 60% yield of the aromatized and acetylated product

95. All spectral characteristics were consistent with the structure

OCOCH
CH Br I 3 CH2Br
89 2 acetic
89 anhydride
4 1 95
94 OCOCH3








-l
proposed. The infrared spectrum gave a strong 1750 cm. carbonyl from

the ester functions. The nmr spectrum had resonances at 67.00 (singlet,

aromatic hydrogens, 2), 66.05 multiplee, vinylic hydrogen, 1), 64.08

(singlet, broad, allylic hydrogens adjacent to bromine, 2), 63.30 (sing-

let, broad, allylic hydrogens, 4) and centered at 62.30 (two singlets,

nonequivalent methyl groups, 3 each). The mass spectrum gave the molec-

ular ion and the molecular ion +2 in the correct percentage for one

bromine atom, m/e 339 and m/e 341. The base peak m/e 176 corresponded

to the loss of both acetoxy groups and the bromine atom.

In the reaction of the acetoxymethyl diene, 79a, with 89 in benzene

at room temperature, quinhydrone,62 the molecular complex of hydroquinone

and quinone, was formed as an insoluble precipitate. It was identified

by its melting point, nmr spectrum and mixed melting point with an

authentic sample. On evaporation of the benzene a dack oil was formed,

which on extraction with hot petroleum ether gave a bright yellow solid

which quickly darkened. Column chromatography on silica gel resulted

in a yellow oil which quickly darkened also. A thin layer chromatogram
-l
yielded two spots. The infrared spectrum gave a strong 3500 cm.1

absorbance indicative of a hydroxyl group. The nmr spectrum was very

complex and from the methyl signal at 62.10, three spikes were apparent

indicating a mixture of three compounds. The bridgehead protons for

the Diels Alder adduct appeared to be present as a multiple at 63.25.

The downfield region centered at 66.80 appeared as a double. From

these data it is believed that the initially formed Diels Alder adduct

80a aromatized to 96. From the color and the apparently three differ-

ent methyl groups, some dehydrogenated material 97 was possibly present

also. All attempts to separate the mixture were unsuccessful. When









the reaction was carried out in ethanol a similar oily solid was

obtained that yielded an infrared spectrum identical to the previous

reaction in benzene.

H
60 0
CH2CH OC C0&
11- 2 3 2 3 C CN

IO II 0C CN
0 0 CH CN
H 96 97 3 98


The acetoxydiene 79a readily reacted with tetracyanoethylene to

yield the Diels Alder adduct 98. Spectroscopic data and the elemental

analysis were all consistent with the normal Diels Alder structure.

At the present time, there appears to be no plausible explanation

why the Diels Alder adducts of p-benzoquinone, 89, and the dienes 77a,

77b, 79a and 94 isomerize so facilely to the hydroquinone derivatives

or dehydrogenate to the quinone like structures. Since quinhydrone

appeared as a byproduct in the formation of 90 and 96, 89 probably ahts

as an oxidizing agent in the reactions.

Although these reactions appear to be the first time such reactions

have been observed to occur spontaneously, Ansell and Knights6 have

reported the facile aromatizations of some Diels Alder adducts of

1,1'-acetoxyvinylcyclohexene, 99, and 89. They found that in ethanol-

0
R= -0CCH3 0
0 0 0



99+ 8 --100. 101 102

99 100 101 102










at room temperature the normal Diels Alder adduct 100, formed in 63%

yield. In refluxing methanol, however, the authors observed the form-

ation of 101 and 102. They offered no reasons for their observations

but did report that most aromatizations of this nature are catalyzed

by acid or by base. A previous synthesis of 10064 revealed that melt-

ing the adduct and then resolidifying resulted in the formation of 101.



2-Cyclohexene-l-one and diazoguinone as dienophiles

As an alternative approach to the synthesis of a precursor

capable of undergoing the cyclization reaction to the cage structures,

it was decided to employ dienophiles whose adducts were incapable of

undergoing the facile aromatization reaction. The two dienophiles

selected for this study were 2-cyclohexene-l-one 103 and diazoquinone

104.

0 0
NI I




0

103 104


If the normal Diels Alder adduct, 105, of 103 and 79a were to

form then it would not be capable of aromatizing. Hence it was believed

that the reactions shown in Scheme VI could be followed.

The synthesis of 103 was accomplished by bromination of cyclo-

hexanone with N-bromosuccinimide65'66 followed Ly dehydrobromination

with colliding. The bromination reaction was accomplished in a

53% yield, while the dehydrohalogenation gave a 58% yield of the

desired a,3-unsaturated ketone, an improvement over the 42% yield









SCHEME VI

0 0
OCCH20CCH^ -1
103 + 79a IH2 OCH3 1) catalytic
hydrogenation

separate 2) Ms Cl



CH OCCH
0
105
10


j Y -CH20Ms base as


106


reported by the original investigators.67 An attempted dehydrobromin-

ation using lithium bromide in dimothylformamide68 resulted in a

yellow viscous oil.
69
From earlier experiments with 103 by Bartlett and Woods, this

dienophile was known to be quite sluggish in the Diels Alder reaction;

therefore forcing reaction conditions were employed.

An autoclave attempt to form the adduct from neat reactants at

2000C resulted in a waxy, gummy, polymeric substance. This material
-1
gave a sharp carbonyl absorbance at 1710 cm.- The nmr spectrum

yielded broad resonances centered at 67.00 (1) and 61.00 (13).

In benzene solution, in a sealed tube at room temperature for

four days,starting materials were recovered. 103 and 79a were then

reacted neat, in the presence of a small amount of hydroquinone, in

a sealed tube at 190C for three days. As in the autoclave reaction,

a polymeric substance was isolated. It had the identical spectral

characteristics of the former polymer.









Aluminum chloride had been found to be'an effective catalyst
70
for sluggish Diels Alder reactions. When the Diels Alder reaction

of 103 and 79a was attempted in the presence of a catalytic amount

of anhydrous aluminum chloride, a vigorous exothermic reaction was

noted and could only be controlled by use of an ice bath. On work up,

an oil was obtained that yielded a double carbonyl absorbance at

1680 cm.- and 1710 cm.- Chromatography on silica gel resulted in
-i -
an oil with a strong 1705 cm.- absorbance and no 1680 cm.-1 absorbance.

The nmr spectrum exhibited resonances consistent with structure 107

with 65.85 multiplee, vinyl hydrogen, 1), 64.05 (singlet, allylic

hydrogens next to chlorine, 2) and 62.20 (multiplet, broad, ring

hydrogens, 12). No resonances that could be assigned to the acetoxy

methyl hydrogens were present.

The mass spectrum gave a parent peak at m/e 198 with a P+2 peak at

m/e 200 which was 35% of the parent. The theoretical P+2 intensity71

for one chlorine atom is 32.6%. The base peak of the spectrum was

m/e 163 corresponding to loss of the allylic chlorine atom.


0
CII2Cl





107


The mechanism is not known for the formation of 107 but one

could speculate that the initial Diels Alder adduct, which appears to

be present in small yield from the infrared spectrum, reacts with

adventitious hydrogen chloride present. It is generally known that a

trace amount of this impurity is contained in aluminum chloride.









The use of diazoquinone, 104, as a dienophile was believed to

be an attractive course of action to pursue to obtain an adduct incapable

of aromatizing. Scheme VII shows the intended reaction sequence.

Kealy54 had reported the synthesis of 104 and had reported it to be

an extremely potent dienophile.

SCHEME VII

SI0 OR 1) catalytic
S / CH 20R hydrogenation
+ 77a,b _
,N CIH 2R 2) MsC1
00 0
108a,b

CH20Ms 0



0
109

0

The synthesis of 104 was accomplished by oxidation of the potassium

salt of maleic acid hydrazide with tert-butyl-hypochlorite at -77C

in acetone. Reaction of 104 with the diacetoxydiene 77a at -55C for

twelve hours yielded 45% of a light yellow crystalline solid which

was consistent with structure 108a in every respect. The infrared
-i
spectrum gave the ester carbonyl at 1730 cm.- and the quinone amide

carbonyl at 1650 cm.-I The nmr spectrum gave resonances at 66.92

(singlet, vinyl hydrogens, 2), 64.80 (singlet, allylic hydrogens

adjacent to nitrogen, 4), 64.57 (singlet, allylic hydrogen adjacent

to acetoxy, 4) and 62.09 (singlet, methyl hydrogens, 6). The elemental

analysis agreed with the calculated value.

The reaction of 104 with the dihydroxy diene 77b yielded the









Diels Alder adduct 108b. Again all spectral characteristics were

consistent with the assigned structure. The infrared spectrum gave

absorbances for the hydroxyl groups at 3480 cm.- and 3400 cm.- The

amide like carbonyl appeared at 1630 cm.-1 The nmr spectrum had

resonances at 66.98 (singlet, vinylic hydrogens, 2), 64.51 (singlet,

allylic hydrogens adjacent to hydroxyl, 4), 64.11 (singlet, allylic

hydrogens adjacent to nitrogen, 4) and 63.50 (broad, probably hydroxyl

hydrogens, no integration). The elemental analysis agreed with the

calculated values.



Attempted catalytic hydrogenation of Diels Alder adducts

The catalytic hydrogenations of the adducts 108a and 108b to the

desired structure for the cyclizations were unsuccessful. Two catalyst

systems were employed and both were chosen for their efficient reduction

of double bonds and their inactivity toward hydrogenolysis of reactive

substituent groups.

The catalyst system, 5% rhodium on carbon, has been successfully

used in the reduction of compound 110 to 111.72 Hydrogenation using

5% palladium on carbon has been found to be efficient in systems

0
II
SRhN/C
[ 1-- ~ \\ >-


0--- =o0 - -'C=o

110 111


containing allylic acetoxy groups. Compound 112 was reduced to 113

using this system.73









0
0 OCH 1.
S3 0 CCH3





0 II
0

112 113


The results of the hydrogenation attempts are shown in Table 7.

In all cases, a mixture of products appeared to be present from the

complex nmr spectra. Attempts at separation by column chromatography

were almost unanimously unsuccessful.

Two distinct trends, however, were apparent from these experiments.

The first was that the quinone like double bond was easily hydrogenated

and the tetrasubstituted double bond was highly resistant to reduction.

In all atmospheric hydrogenations almost always approximately one-half

of the theoretical hydrogen uptake was recorded in the first fifteen

minutes. In experiment 3, the hydrogenation of 108b with 5% rhodium

on carbon in ethyl acetate, a compound was isolated and purified and

assigned structure 114. The nmr spectrum showed an absence of the







11 2
,CH20H


CH20H
0
114

quinodial protons of the starting material and gave resonances at

64.29 (singlet, allylic hydrogens adjacent to hydroxyl, 4), 64.10

(singlet, allylic hydrogens, 4), 63.87 (singlet, broadened, hydroxyl

hydrogens) and 62.60 (singlet, hydrogens adjacent to carbonyl, 4).










In a hydrogenation attempt under more forcing conditions, i.e.,

5% rhodium on carbon at 35 psi., a white crystalline solid was isolated

that melted at 151-40C. The nmr spectrum was indicative of structure

115 which could result from the hydrogenolysis of a carbon nitrogen

bond. The resonance signals recorded were 64.31 and 64.13 (two over-

lapping broad singlets, allylic hydrogens, 4), 62.65 (singlet, hydrogens

adjacent to the carbonyls, 4) and 61.75 (broad singlet, allylic methyl

hydrogens, 3). The mass spectrum gave the correct parent peak at

m/e 228 and the base peak at m/e 210.


0
H CH 3
--CH2OH

11 2
0
115

The resistance to hydrogenation of the tetrasubstituted double

bond was not surprising since at least one report of a similar case
74
is documented in the chemical literature. Gillis and Beck attempted

to hydrogenate 116 with Pd/C, Rainey nickel and Pd/Al2)3 at 59 psi

and were unsuccessful.


0
-COC2CH3
/N-^ 0CH2CH3
xJ-qOCH 2 Ctl3


116


Hydrogenation of the double bonds of compound 90 was recognized

as another route to 24. At atmospheric pressure hydrogenation with

5% rhodium on carbon in ethyl acetate resulted in the absorption










TABLE 7. CATALYTIC HYDROGENATION OF DIAZOQUINONE ADDUCTS


Conditions

Rh/C, ethyl acetate
atmospheric pressure
"


Experiment

1


2

3

4


5


6


Substrate

108a


108a

108b

108b


108b


108b


Product

unidentified oil
2250 cm.-1 ir



114

unidentified oil
2250 cm.-1 ir




unidentified oil


115


of one third the theoretical amount of hydrogen. On work up a white

solid was obtained with all spectral characteristics identical to its

hydroquinone derivative 91.



Attempt to prepare precursor to intramolecular Diels Alder pathway

27, the Diels Alder adduct of 2,3-di(bromomethyl)l,3-butadiene

and p-benzoquinone, was smoothly prepared by the method of Butler and
29
Ottenbrite.29 The 1,4-elimination of bromine from this compound by

the use of zinc in dimethylformamide28 to yield 28 was unsuccessful.

Attempts to trap the intermediate diene with maleic anhydride and

tetracyanoethylene were unsuccessful. In each case unidentifiable

soluble polymeric material was obtained. Since Alder and Fremery28

had postulated diradical-intermediates in their investigation of the

zinc dimethylformamide system, it is possible that the diene formed

but then quickly polymerized.


Rh/C, ethyl
atmospheric

Pd/C, ethyl
atmospheric

Pd/C, ethyl
atmospheric

Rh/C, ethyl
35 psi


alcohol
pressure

alcohol
pressure

acetate
pressure

acetate


108b









B. Attempted Synthesis of 5,5,6,6-Tetrasubstituted Cyclohexadiene

Structures

Proposed syntheses

Two synthetic routes were investigated as possible means to

generate 5,5,6,6-tetracyanocyclohexadiene, 29. Earlier work75 had

shown that the Diels Alder adduct of butadiene and tetracyanoethylene,

117, was resistant to halogenation reactions. The routes investigated


CN CH3 CH3

-CN FA
-\N 1

117 118 119


were the reaction of tetracyanoethylone with a-pyrone, 118, and with

3,4-dimethylthiophene-l,l-dioxide, 119, and then subsequent loss of

carbon dioxide or sulfur dioxide to the desired tetrasubstituted diene.



Adducts of a-pyrone

118 was synthesized by the excellent preparation of Zimmerman and
76
coworkers. Surprisingly the cisoid diene failed to form the desired

Diels Alder adduct with tetracyanoethylene under a variety of conditions.

Upon mixing the two reactants, a strong reddish-brown color was always

observed; however either starting materials or black tars were re-

covered from each reaction as summarized in Table 8.

The failure of tetracyanoethylene to form a Diels Alder adduct

with 118 is surprising since this diene has been observed to be quite

reactive with rather unreactive dienophiles. Fieser and Haddadin77

observed 118 to react with the unusual dienophile 120 to yield 121.












0 1180 0-

0


120 121



Diels and Alder78 observed the formation of the Diels Alder adduct

with maleic anhydride. This reaction was successfully repeated.

Successful Diels Alder additions of 118 with both p-benzoquinone

and fumaronitrile to yield 122 and 123 were observed. 122 was

C0
S0 0--0




122 0 123

-1
characterized by the infrared spectrum which gave both a 1750 cm.
-l
ester carbonyl and a 1655 cm.- quinone carbonyl. The nmr spectrum

yielded resonances at 66.82 (singlet, quinone hydrogens, 2) 66.57

(triplet, vinylic hydrogens, 2), 65.69 (quartet, allylic hydrogens

next to oxygen, 1), 64.21 (quartet, hydrogen next to carbonyl, 1) and

63.60 (two doublets, bridgehead hydrogens, 2). The elemental analysis

was satisfactory for 122.

The fumaronitrile adduct, 123, gave weak infrared absorbances

for the nitrile groups at 2245 cm.-1 and 2200 en.-I The ester
-l
carbonyl absorbance was at 1755 cm.- The nmr spectrum gave resonances

at 66.92 multiplee, vinylic hydrogen, 2), 65.80 multiplee, hydrogen

adjacent to oxygen, 1), 64.08 multiplee, unassigned, 2) and 63.63










multiplee, unassigned, 1). A correct elemental analysis was obtained.

Both dimethyl maleic anhydride and tetraethylethylenetetracarboxyl-

ate failed to form the Diels Alder adduct also. It is probable that

tetracyanoethylene along with these two dienophiles failed to react

because of steric interference. Under the forcing conditions, where

the tars were obtained, it is possible that the adduct formed, lost

carbon dioxide and then the resulting diene thermally polymerized

under the severe reaction conditions.



Adducts of 3,4-dimethylthiophene-l,l-dioxide

3,4-Dimethylthiophene-l,l-dioxide, 119, was prepared by first

the bromination of 2,3-dimethylbutadiene sulfone, 82 to the dibromide

124 and then dehydrohalogenation with sodium methoxide in tetrahydro-

furan. The results of this reaction were not reproducible. Sometimes

119, the desired product, was formed in good yield, while at other times
79
125 was formed. The literature preparation of 119 involved oxidation


CH3 CH3
Br -Br YH3


02 02

124 125

of the corresponding thiophene to the thiophene dioxide. A reported

dehydrobromination80 of 124 with potassium hydroxide only yielded 125.

119 was found to be unreactive with tetracyanoethylene in the

same manner as was a-pyrone. However, maleic anhydride reacted with

119 in refluxing toluene'to form 126.

This compound was identified by its infrared spectrum with an










TABLE 8. REACTIONS OF TETRACYANOETHYLENE WITH a-PYRONE


Experiment


Solvent


neat

tetrahydrofuran

neat
XS pyrone

neat

xylene

toluene

benzene

tetrahydrofuran


anhydride carbonyl 1850 cm.-L
anhydride carbonyl 1350 cia.


and 1780 cm.-1
and 1780 cm.


The nmr spectrum exhibited


resonance signals at 63.55 (siOglet, broad, hydrogen adjacent to

carbonyl, 4), 63.20 (singlet, broad, hydrogens at bridgehead, 2) and

61.62 (singlet, allylic methyl hydrogen, 6). The mass spectrum

yielded a molecular ion at m/e 276.


Temperature Time
(hrs)

ambient 72

reflux 48

140C 2
reflux

100C 24

reflux 48

reflux 44

reflux 45

sealed
tube 600 188


Product


no reaction

no reaction

black tar


black

black

black

black


no reaction
















CHAPTER IV


Experimental

A. General

All melting points and boiling points are uncorrected and reported

in degrees centigrade. Melting points were determined in open capil-

lary tubes on a Thomas-Hoover capillary melting point apparatus.

Pressures are reported in millimeters of mercury. Elemental analyses

were done by Galbraith Laboratories, Inc., Knoxville, Tennessee,

Peninsular ChemResearch, Inc., Gainesville, Florida or Atlantic Micro-

lab, Inc., Atlanta, Georgia.

Infrared spectra were recorded with either a Beckman IR 10 or

a Beckman IR 8 Spectrophotometer. Visible spectra were recorded on

a Beckman DK-2A Spectrophotometer. Proton nuclear magnetic spectra

were obtained by use of a Varian A-60 Spectrometer and all resonances

are given in the chemical shift parameter 6 and are measured from

tetramethylsilane (TMS) as an internal standard. Mass spectral data

were obtained using a Hitachi Perkin-Elmer RMN mass spectrometer.

All solvents were commercial reagent grade and used as received

unless specifically noted. Polymer nonsolvents were technical grade

and were filtered before use. All chemicals used as reactants were

obtained commercially and used as received unless specifically

designated as otherwise.

The comonomers divinyl ether, ethyl vinyl ether, isobutyl vinyl

ether, styrene, acrylonitrile, divinyl sulfone and vinyl acetate were










obtained from commercial sources and distilled immediately prior to use.

Divinyl carbonate and N-vinyl carbazole were obtained in high purity

from commercial sources and used without further purification.

Number average molecular weights were obtained from a Mechrolab

Model 302 Vapor Pressure Osmometer. Molecular weight distributions

were obtained from a Waters Associates GPC 300 Gel Permeation Chromato-

graph. Thermal characteristics of the polymers were recorded by a

Perkin-Elmer DSClB Differential Scanning Calorimeter. Intrinsic

viscosities were measured employing a Cannon-Ubbelohde semimicro

dilution viscometer using standard procedures for operation and

calculations.



B. Copolymerizations and Related Reactions of 4-Substituted 1,2,4-

triazoline-3,5-diones

1. Synthesis of 4-phenyl and 4-methyl-l,2,4-triazoline-3,5-diones
81
Ethyl carbazate -Diethyl carbonate (2Q00 g., 1.80 mol.). and

88.0 g. (1.80 mol.) of 99% hydrazine hydrate were shaken together

for approximately 20 minutes. Some exothermicity was observed and

after this time the original two phase system blended into one phase.

The solution was left standing overnight. Distillation at 95C and

12 mm. yielded 147.7 g. (83.5%) of a clear liquid which solidified

on standing to a white solid, m.p. 43-45.5 (lit.81 44-45.5).
82
l-Ethoxycarbonyl-4-phenylsemicarbazide -Ethyl carbazate (70.0 g.,

0.67 mol.) was placed into a 500 ml. round-bottomed, three-necked

flask with 350 ml. of benzene. The flask was equipped with a magnetic

stirrer, a reflux condenser guarded by a calcium chloride drying tube,

a dropping funnel and a thermometer. After refluxing to get the










ethyl carbazate into solution, the solution was cooled to 10. Through

the dropping funnel 70.0 g. (0.59 mol.) of phonyl isocyanatewere intro-

duced at a rate -.hich kept the temperature between 100 and 200. After

all the isocyanate was added, the resulting white solid slurry was

refluxed for 20 minutes and then cooled and filtered. After drying

under vacuum 124 g. (89%) of the desired product m.p. 152-3' (lit.82

m.p. 154') were obtained.

4-Phenyl urazole82-To 275 ml. of hot 4M potassium hydroxide, 124 g.

(0.55 mol.) of l-ethoxycarbonyl-4-phenylsemicarbazide were added in

small portions while shaking the potassium hydroxide solution on a

steam bath. After the addition was completed, the solution was main-

tained on the steam bath for an additional 20 minutes. The solution

was cooled and carefully acidified with concentrated hydrochloric

acid. The precipitate was removed by vacu-um filtration and extracted

with 95% ethyl alcohol via a Soxhlet extractor. On cooling and then

treating the mother liquor 69.2 g. (70.3% yield) of the urazole m.p.
82
204-7' (lit. 82.p. 206-7') was obtained.

4-Phenyl-l,2,4-triazolina-3,5-dione, PhTD -Anhydrous sodium

sulfate, 25.0 g., was placed into a 500 ml. Erlenmeyer flask with

300 ml. of methylene chloride and 6.0 g. (0.034 mol.) of 4-phenyl

urazole. The slurry was stirred by a magnetic stirrer and cooled to

0-5' with an ice-water bath. By means of a pipette attached to a gas

cylinder with a tube, dinitrogen tetroxide was bubbled slowly through

the solution. The temperature was kept below 5'. after a few minutes

a deep red color developed. After all the urazole appeared to have

been consumed, usually in about thirty minutes, the sodium sulfate

was removed by vacuum filtration and the deep red solution was









evaporated using lukewarm water on a rotary evaporator. 4.8 g. (80%

yield) of dark red crystalline PhTD was obtained. Purification was ac-

complished by sublimation at 70-750 under a vacuum of less than 0.5 nn.

The red solid was stored in the absence of light in a freezer until it

was used.

4-Methyl-l,2,4-triazoline-3,5-dione, MTD -The same procedure used

in the synthesis of PhTD was employed in the synthesis of MTD. This
83
synthesis had been previously reported in the literature.83 ethyl iso-

cyanate was added to the ethyl carbazate and a quantitative yield of the

corresponding semicarbazide derivative was obtained. This was cyclized

with 4M potassium hydroxide to the corresponding 4-methyl urazole in a

yield comparable to the phenyl derivative. Oxidation with dinitrogen

tetroxide was accomplished in approximately 90% yield. The light red

fluorescent appearing powder was purified by sublimination at less than

0.1 mm. and a temperature between 50 and 60.



2. General copolymerization procedures

a. Spontaneous copolymerizations

The following experimental procedure was typical of all spontaneous,

room temperature ccpolymerizations unless specifically noted otherwise.

All glassware, i.e., Erlenmeyer flasks, syringes and volumetric

flasks were scrupulously cleaned, rinsed with acetone, dried in an 80*

oven and then allowed to cool to room temperature in a large desiccator.

On removal from the desiccator the flasks were immediately capped with

serum caps. Solvents were reagent grade and dried for a minimum of 24

hours over 3A molecular sieves.

Ethyl vinyl ether, EVE, PhTD copolymerization-A 50 ml. Erlenmeyer









flask equipped with a magnetic stirring bar and a rubber serum cap was

charged with 0.499 g. (2.84 mmol.) of PhTD by removing the cap and adding

as a solid. Next, 15 ml. of methylene chloride were introduced using a

syringe and adding through the serum cap. This was followed by the add-

ition of EVE (0.203 g., 2.83 mmol.) in the following manner. The vinyl

ether was carefully weighed into a 10 ml. volumetric flask through a

serum cap and then the flask was brought to volume with methylene

chloride. A careful quantitative transfer to the reaction vessel was

made using a syringe. The reaction mixture was stirred and within two

minutes the dark red colored solution, characteristic of PhTD, was

discharged to yellow. After 30 minutes the reaction mixture was pre-

cipitated by dropping slowly through a coarse filter frit into cold

hexane. The hexane solution was filtered to yield 0.615 g. (86% yield)

of a white-yellowish granular appearing solid. The solid appeared to

soften at 1000 and above 1500 it darkened and decomposed. The number

average molecular weight was determined to be 1660 by use of a Vapor

Pressure Osmometer in acetone solution. The infrared spectrum (KBr)

showed absorbances at 2980 (w), 1770 (w), 1715 (s), 1610 (s), 1500 (m),

1470 (m), 1420 (n), 1310 (m), 1130 (n), 1070 (w), 900 (w), 820 (w),

760 (m) and 700 (m) cm.I The nmr spectrum (CDC3 ) gave resonance

signals at 67.45 (s, broadened, 5), 66.00 (m, broad, 1), 63.83 (m, broad)

and 61.16 (t, broad, 3). The spectrum is shown in Fig. 1.

Anal. Calcd. for a 1:1 copolymer structure, C12 H3N303: C, 58.30;

H, 5.26; N, 17.00. Found: C, 58.08; H, 5.14; N, 17.16.

Table 1 contains a summary of experimental results of all EVE-

PhTD copolymerizations.









b. Copolymerizations at 600

The following experimental procedure was typical of all copolymer-

izations at 60 unless specifically noted otherwise.

The copolymerizations were effected in heavy walled 13 cm. x 3 cm.

Pyrex tubes. All glassware i.e., Pyrex tubes, syringes and volumetric

flasks was thoroughly cleaned, rinsed with acetone, dried in an 80"

oven and then allowed to cool to room temperature in a large desiccator.

On removal from the desiccator the volumetric flasks and the polymer

tubes were sealed with serum caps. Solvents were reagent grade and

were dried for a minimum of 24 hours over 3A molecular sieves. Copolymer-

izations were conducted in a 600 oil bath regulated by a Sargent NS1-

12 controller to 0.1.

Copolymerization of divinyl ether, DVE, and PhTD at 60-A heavy

walled Pyrex polymer tube, capped with a serum cap, was charged with

0.508 g. (2.81 mmol.) of PhTD by removing the cap and adding the solid.

This was followed by the addition of 15 ml. of methylene chloride by.

means of a syringe. Next DVE (0.200 g., 2.82 immol.) was carefully

weighed into a 10 ml. volumetric flask using a syringe and adding

through a serum cap. The flask was brought to volume with methylene

chloride and then carefully transferred to the polymer tube by means of

a syringe. The polymer tube was then placed on the high vacuum line
-4
and carried through a freeze-thaw degassing cycle using a 10 mm.

vacuum. The tube was sealed and warmed to room temperature before

placing in the 600 bath. After 24 hours at 600 the originally red

colored solution had changed to yellow. This color change normally

took place within a few minutes after placing the tube in the bath. The

tube was removed from the oil bath after 24 hours, cooled to room temp-




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