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 A study of unconjugated chromophoric...
 Cyclopolymerization involving cumulative...
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Title: study of unconjugated chromophoric interactions related to cyclopolymerization.
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Title: study of unconjugated chromophoric interactions related to cyclopolymerization.
Series Title: study of unconjugated chromophoric interactions related to cyclopolymerization.
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Creator: Brooks, Thomas William,
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Table of Contents
    Title Page
        Page i
        Page ii
    Table of Contents
        Page iii
        Page iv
    List of Tables
        Page v
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
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        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
    A study of unconjugated chromophoric interactions
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
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        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
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        Page 36
        Page 37
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        Page 39
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        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
    Cyclopolymerization involving cumulative 1,2 and 1,4 addition
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
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        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
    Biographical sketch
        Page 68
        Page 69
Full Text







August, 1961


The author wishes to express his deep appreciation to

Dr. G. B. Butler whose guidance and counsel during the execution

of this work were of inestimable value.

The author wishes also to express his gratitude to the

members of his advisory committee and his fellow graduate

students whose advice and criticism was a constant source of

inspiritation and encouragement.

Special thanks are due Mrs. Marie Eckart for her diligence

and conscientousness in the typing of this dissertation.

Finally, the author wishes to express his great appreciation

to his wife, Lucretia, whose forbearance and understanding during

months of neglect made this work much easier.

The financial support of this research by The American

Chemical Society Petroleum Research Fund is also gratefully




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

LIST OF FIGURES .......... ... v


I. INTRODUCTION . . . . . 1

A. History of Cyclopolymerization . 1

B. Non-conjugated Chromophoric

Interactions. . . . 11



A. Selection and Synthesis of Model

Compounds . . . 19

B. Results and Discussion . . 25

CS Experimental . . . . 37



A. The Polymerization of

1 3, 8-Nonatriene . . . 51

B., Experimental . . 54



IV. SUMMARY ..... . . . 57

APPENDIX . . . . . . .. 59

BIBLIOGRAPHY .. ... ......... 6Z



Table Page

1. Olefins Found to Undergo Cyclopolymerization. 7

2. Selective Absorption of Butadiene Derivatives . 26

3. Selective Absorption of Styrene Derivatives . . 29

4. Selective Absorption of Methacrylate Derivatives

in Isooctane . . .. . . . 33


Figure Page

1. Ultraviolet Absorption Spectra of cis and

trans-1,3,8-Nonatriene in Ethanol . . 27

2. Ultraviolet Absorption Spectra of Styrene

Derivatives in Ethanol . . . . 31

3. Ultraviolet Absorption Spectra of Methacrylate

Derivatives in Isooctane . .. . 34



A. History of Cyclopolymerization

Cyclopolymerization* or intramolecular-intermolecular
polymerization is a phenomenon observed with certain 1,5- and
1,6-dienes by which a polymer is formed having cyclic recurring
units. The process is Illustrated as follows.


* Cyclopolymerization is a somewhat ambiguous term for

F- 0


that 31% of converted monomer should undergo some kind of

cyclization in the polymerization of diallyl phthalate. Simpson's

results are in fair agreement with the prediction and further work

has been pursued in this direction. 7 Oiwa and Ogatae subsequently

found that diallyl phthalate will yield a polymer by solution polymeri-

zation which is 81% cyclized.

The mechanistic implications found in earlier work were

not fully realized until Butler and Angelo9 made their dramatic

proposal that l,6-dienes could polymerize by an alternating

intramolecular-intermolecular process to afford soluble, fully

saturated polymers containing recurring six-member cyclic units.

The soluble polymers produced by polymerization of diallyl

quaternary ammonium salts were thus accounted for. A rigorous

structure study Butler, Crawshaw, and Miller10 substantiated

the cyclopolymerization hypothesis. The study involved degrading

poly-(diallylammonium bromide) I and poly-(diallyldimethylammonium

bromide) IV via the following schemes.

e e Ococi
N Br
-n -n

Butler and IngleyI found that diallyl quaternary ammonium

salts polymerized with free radical initiators to yield water-soluble,

non-crosslinked polymers. They found on the other hand that

monoallyl quaternary ammonium salts would not polymerize and

that the triallyl homologs polymerized to yield crosslinked products.

In view of Staudinger's hypothesis that non-conjugated dienes yield

exclusively crosslinked polymers, it was not expected that any

1,6-diene would yield a soluble polymer. The possibility of

cyclization occurring during the polymerization of a non-conjugated

diene had been recognized even before Butler's original work.

Walling3 had commented on the fact that observed gel-points for

some dienes should occur later than calculated by Stockmayer's4

equation because the equation failed to account for occasional

cyclization. Thus it was found that for the systems methyl methacrylate-

ethylene dimethacrylate and vinyl acetate-divinyl adipate, the ratios

of observed to calculated gel-points were frequently as high as

fifteen to twenty. Simpson, Holt, and Zeite5 -i their polymeri-

;atio.n studies of diallyl phthalate found that 40% of the units were

cyclized in the polymer. Award6 predicted by statistical calculations

intramolecular-intermolecular polymerization, but Sinco the term has
been allowed to slip into the literature and is less cumbersome than
alternative expressions, it will probably enjoy a wide usage except
with the terminological purists.


1. to hydrox.
Z, 2 thermal
N Br decomp.




CH3J n



The structure of III was supported by elemental analysis,

potcntiometric titration, infrared opectral analysis, and the fact

that heating above its miclting point yielded a sublimate of benzoic

acid plus a crosEllnked polymer residue. The structure of VI was

supported by similar data and the fact that thermal degradation of

the corresponding hydro:dde yielded trimethylamine and a crosllinhed

polymer residue.

With the work discussed above providing the impetus, a

considerable research effort has been generated in the field of

cyclopolymerization. A polymer of diacrylylmethane has been

found by Jones11 to result from attempts to cause a Claicen

condensation of methyl vinyl ketone and ethyl acrylate. The

expected product apparently undergoes an anionic polymerization

to yield a soluble polymeric material having the properties of a

poly-(dihydroresorcinol). Marvel and Stille12 have demonstrated

that 1, 5-hexadiene and 1, 6-heptadiene yield soluble predominately

saturated polymers by the cyclic mechanism when polymerized with

a Ziegler catalyst. The hexadieno, however, was observed to give

a considerable amount of crosslinked material also. Field13 has

described the synthesis and polymerization of 2, 6-diphenyll1, 6-

heptadiene and has found that a soluble polymer may be derived from

this monomer by all four known modes of chain initiation. Schuller

and co-workers14 have reported copolymers of diallyl compounds

with such conventional vinyl monomers as acrylonitrile which they

claim have cyclic units arising from cyclization of the diene comer.

Soluble copolymers of diallylalkylamine oxides and conventional

vinyl monomers probably contain cyclic units also, though their

properties are not ascribed to this structure. 15 Quite recently the

formation of bicyclic recurring units by the cyclopolymerization

procsoo has been reported. Ball and Harvwood16 claim to have

obtained a polymer of 1, 4-dimethylenecyclohexane in which the

repeating units are norbornyl rings. Trifan and Hoglen17 have

obtained data which strongly suggest that certain triencs and

tctracnes such as triallyl and tetraallyl ammonium bromides may

polymerize in dilute solutions to yield bicyclic and tricyclic

analogs of the poly-(diallylammonium halides).

Table I lists all of the monomers reported up to the present

time which have been shown to undergo cyclopolymerization.

In addition to monomers of the type in Table 1, certain

1,4-dienec may be expected to cyclopolymerize in copolymer systems.

Butler,30 for instance, has found that divinyl ether yields a soluble

polymer when copolymerized with such monomers as maleic


In an effort to account for the unique tendency of the diene

systems under consideration to cyclopolymerize, it has been

proposed30 that a homoconjugative interaction occurs between the

unconjugated ethylenic bonds. A schematic representation of this

phenomenon is shown below.

-,0 )-(



Olefina System

Acrylic Anhydride

N.AUIyl -N 2-chloroallylmorpholinium

N-AUlyl-N- chloroalUylpperidinium

AUylmethyl fumarate

Allylmethyl maleate


Allylphenyl allylphosphonate

N-Allyl-N-tranc-3- chloroallyl-
morpholinium bromide

3-Butenylmethyl fumarato

3-Butenylmethyl maleate

2-Carbethoxybicyclo(2 2. 1)-2,5-

C rotylmethyl fumarate

Crotylmcthyl malcate

Dia c rylyl methane

Diallylammonium bromide



_ .... L .__ _._.~._~_~._ .. ..._~ __~.____

TABLE 1 (Continued)

Olefina System Reference

Diallylammronium chloride RI 10

Diallylbenzylamine oxide R 15

Diallylcyclopentamethylenesilane Z Z3

Diallylcyclotetramristhylenesilane Z 22

Dialyldiethylammonium bromide R 9,14

DiaUyldimethylammonium bromide R 9,10

Diallyldimethylsilane Z 23

Diallyldiphonylphosphonium bromide R 19

Diallyl phthalate R 5,8

Diallyldiphenylsilane R, Z 24

Diallylethylamine oxide R 15

Dialylmethylamine oxide R 15

bromide R 19

Diallylphcnylphoslphine o:idc R 20

Diallylphenylmethylphos phoniurn
bromide R 19

Diallylphenylpropylphos phonium
bromide R 19

Dimethallylamine oxide R 15

TABLE I (Continued)

Olefina System Reference

Dim ethallyleyclopentamethylenes lane

Dim ethallyldmeothyls iane






DimcthallylphoA phine o::ide


a, c -Dlrmethylenepimelonrit le

2, 5-Dimethyl-1, 5-hexadiene

2, 6-Diphenylol, 6-heptadiene

2, 5 Diphenyl-1, 5 -hexadiene

2, 7-Diphenyl-l, 7-octadiene

Divinyl adipate

Ethylene dimethacrylate

1, 6-Heptacliene





R,C, Z

R, C, z















TABLE 1 (Continued)

Olefina System Reference

1, 6-Heptadiyne Z 25

1, 5-Hc:dicne Z 24

Mcthacrylic anhydride R 28

I yrceno C 67

aa'-Pimclic acid R 29

p,a'-Pimelic acid methyl ester R 29

aa'-Pimclic acid ethyl etecr R 29

Tetraallylammonium bromide R 17

Trial-ylammonium bromide R 17

3-Vinyl-1, 5 -hedadiene Z 17

a. It will be noted that monomers have been included
which do not yield exclusively linear saturated

b. R = Free radical A= Anionic
Z = Ziegler initiator C= Cationic

,rhile it aoeom presumptuous to suggest that ouch a

phenomenon would contribute greatly to the ground otate of a

molecule, it does not seem unlikely that it would have a stabilizing

influence on the excited state, thus, providing an energetically

favorable path from dienc to cyclic product. Thic subject will be

developed further in the following section of this paper.

B. Non-conjugated Chromophoric Interactions

For many years it was believed a fundamental principle of

ultraviolet spectroscopy that chromophores separated by two or more

single bondo were additive in their absorption of light. 31 As the

literature on ultraviolet spectroscopy grcw, however, there began

to appear some notable c::ccptions to this principle. Ley, Wingchen,

and Dirking, 32, 33 for instance in their otudics of ultraviolet spectra

of hetones found that the absorption maximum of acetone could be

shifted to longer wavelengths by phenyl substitution. Thus they

observed that the maxima for a series of ketonce were in the order

acetone < phenylacetone < dibcnzylhetonc < acctophenone <

dc-o::ybcn-oin < bon=ophononc. A noticeable effect of unconjugatcd

groups on polyene absorption has been observed with certain

carotenoids. 3 Various other instances of apparent c::ccptions to

the additivity principle are extant in the early literature, though they

are few in number. 31

Attempts to interpret the non-additive ultraviolet absorption

of certain chrornophoric systems gave rise to two schools of

thought. Ingold, Shoppee, and Parekh35, 36 must be credited with

the first interpretation, even though it was based largely on chemical

rather than spectral observations. A peculiar lack of olcin

reactivity combined with a facility for cyclization of methyl and

ethylAl1 hexadiene-l:, 3:3,4:4, 6:6-octacarboxylatc was attributed

by the Ingold school to an interspacial interaction of the olefinic

bonds, or what they called a ring-chain mecomerism. A second

interpretation came about as a result of x-ray and ultraviolet

spectral studies on the same dienc by Bateman, Jeffrey, and

och. 37, 38 They found that the x-ray pattern for the ethyl ester

was incompatible with a cis conformation in the crystalline state

and on this basis concluded that Ingold's ring-chain mn nomorism

hypothotis was incorrect. They chose, instead, to interpret Ingold'o

chemical data and their own spectral and x-ray data in terms of a

hyperconjugative effect involving the entire carbon framework of

the molecule.

Draude and co-workers39 then found that 2,5-dihydro-

acetophenones exhibited a bathochromic shift of the carbonyl

aboorption band over that of 1-acetylcyclohexane. It was found,

furthermore, that the 2-substituted dihydroacetophenones did not

chow a shift. They chose to interpret this as a hyperconjugative

effect involving the methylones situated between the ethylcnic bonds

as illustrated below.

0 H 0 0
Oi II 1 'C II1
-C--CH3 -CH --CH


Thus, they were able to account for their own observations as well

as those of Ley et al. 32 33

To extend the hyperconjugative argument Braudc40

undertook an investigation of compounds of the type X- CHI Y and

X- CH2CH2- Y, where X and Y may represent like or unlike

chromophoric groups. Diphonylmethanc and bibonzyl, each of which

is a representative example of the two types, exhibited departures

from additivity in absorption of ultraviolet radiation. In light of

those results and in view of the fact that x-ray data for bibenzyl

ruled out any interspacial ring interaction in the crystalline state,

it was concluded that a hyperconjugative effect was responsible for

the non-additivity of the unconjugated chromophores.

In more recent years there has been a growing tendency for

theoreticians to favor the interspacial resonance interpretation.

A number of systems have been found which exhibit chemical and

physical properties indicative of such a phenomenon. Bartlott and

Lewis41 have observed that the ultraviolet absorption maxima of

trypticin are more intense by 3.3 and 5.5 times respectively and are

shifted bathochromically by nine and seven millimicrons from their

apparent equivalents in triphenylmethane. While it is impossible

to draw any cononical forms for trypticin which involve hyper-

conjugation, no less than one hundred eight forms may be drawn

involving transannular interaction of the aromatic rings. An even

more dramatic example of this phenomenon is furnished by the case

of bicyclo(2. 2. l)hcptadiene VII. WVinstein and Shatavolhyy42,43

have found that this compound adds one mole of such reagents as

bromine or the hydrogen halides to yield predominately saturated

products having a nortricyclenic structure. The reaction is shown



+ BrZ r Br

ca. 207% ca. UO',J
VII trans:cis ca. 2

Heato of hydrogenation experiments by Turner and co-workers4

have established that there is no ground state stabilizing interaction

of the rr orbitals in VtI. Wilcox, Winstein, and Mc'Millan,45 on the

other hand, have been able to establish that such interaction does

have a stabilizing effect on the excited state thus, accounting at

least partially, for the unique chemical behavior of the bicyclic


Spectral data have been reported by others46,47 which also

lend themselves well to interpretation in terms of interspacial

electronic interactions, particularly in rigid cyclic systems.

While most of the evidence for unconjugated electronic

interactions has come from studies of rigid cyclic systems, it does

not seem unreasonable to expect that such a phenomenon might be

operative in open-chain systems as well. Ingold's work in this

regard has already been cited and more recent work is equally

deserving of consideration. It has been shown in a variety of open-

chain compounds that a rr-electron system neighboring a developing

carboniurn ion center can e:ert a significant influence on the course

and the rate of a reaction. Simonetta and V'inotolin4 have noted a

* For leading references on this subject see ref-rence 44.

correlation between this phenonemon and the light absorption

properties of ketones such as VII, which exhibit a bathochromic

shift and an enhanced intensity of the carbonyl absorption frequency.

R1-C f-C-CH3


Cram and T'ilkinson,49 in an effort to understand the nature

of the electronic interactions between the aromatic rings of

paracyclophanes, studied compounds of the type IX.



It was found that those compounds in which n= 1, 23,4 would form

only the r ono(tricarbonylchromium) complex when reacted with

ihe:amcarbouylchromium. When the pa positions were substituted

wv'ith ethyl groups, however, electronic interaction was sufficiently

stcrically hindered for the Tr-syotems to appear independent in

their behavior.

With the data existing at the present time it is questionable

whether or not one would be justified in rejecting the hyperconjugative

interpretation for unconjagated chromophoric interactions. It is

significant, however, that this argument rests largely on the results

of x-ray experiments which measure molecular configuration in the

crystalline state only. Since spectral measurements were made in

solution, where the molecular configuration of an open-chain is not

constrained by crystal forces, one can only assume that one or

another configuration obtains. Consequently, one can only speculate

on molecular configuration in a radiation induced excited state,

particularly in the absence of confining steric effects ouch as found

in ortho-substituted biphenyls. 50 In view of Koch's51 observation

that 1,10-diphenyl-l, 9"decadiene is non-additive in absorption of

ultraviolet light and the work of Cram,49 total rejection of Ingold's37'38

postulated interopacial resonance interaction secms unjustified.

One can only conclude that while the whole problem lacks sufficient

data for an unequivocal answer, there is every indication that

interopacial Tr*orbital interactions can occur to produce unique

chemical and physical properties in certain systems.

A systematic investigation of Tr-bond interactions and the

attending chemical consequences in 6-dienoid cystome has never

boen undertaken, although Butler30 has pointed to number of

instances where data are suggestive of such a phenomenon. Aside

from the many cyclic polymers which have been characterized,

there is only one piece of physical evidence which gives direct

support to the postulated interactions of 6-dienes. Mikulasova

and Hvirik5 found the total activation energy for the polymerization

of diallyldimethylsilane to be nine klocalories per mole per double

bond lower than for allyltrimethylsilane. This represented a decrease

in the overall activation energy of some 30%.




A. Selection and Synthesis of Model Compounds

The choice of model molecules with which to study

unconjugated chromophorie interactions such as those proposed by

Butler30 was governed by three major conslderations. The first

consideration was simply the commercial or synthetic availability

of the compounds. Secondly, it was necessary, because of

instrumental limitations, that the chromophores absorb ultraviolet

radiation at wavelengths above 190 millimicrons. Finally, it was

deemed necessary that the compounds studied be as closely related

as possible to system which are Inown to be capable of polymerizing

by the cyclic mechanism. With the above considerations in mind,

three series of compounds were studied spectrophotometrically in the

region of the ultraviolet spectrum extending from 190 to 270


The three series of compounds investigated in this work

were (1) butadiene derivatives, (2) styrene derivatives, and

(3) mcthacrylate derivatives. Synthesis of the butadine derivatives

and the styrene derivatives constituted a -major portion of the

c::perimental work required to gather the spectral data in this

investigation. The methacrylato derivatives, fortunately, were all

commercially available in high purity.

The butadiene derivatives synthesized in the course of this

study were the cis and trans isomers of 1, 3, 8-nonatriene. The cis

icomer was obtained via the following sequence of reactions.

+ Br2 -
0 O
NH3 1 Cz2HOH

SAlc. KOH Dr
o OCzH5 O OCzH5

He I HO0




The six step cynthosis of the intermediate pentadienyl

chloride wao first worked out by Woods and Lcderlc54 and latcr

improved upon by Crombie, Harper and Thompson. 55 The latter

authors assigned the trans configuration to the chloride, basing

their assignment largely on infrared data and the chemistry of

related compounds. It was presumed that while the pcrcurcor cyclic

acetal constrained the molecule into the c c configuration, a cis to

trans interconversion occurred during acid hydrolysis of the acetal

to the pentadienal.

On the basis of the evidence obtained in the present work,

the trans assignment for the pentadienyl chloride is believed to be

incorrect. The triene obtained by coupling of the pentadienyl

chloride with 3*butenylmagnesium bromide has definitely been

established to be a geometrical isomer of the trinoc obtained by the

WVittig56 reaction of 5-hexenyltriphenylphosphonium bromide with

acrolc.n. The boiling points, refractive indices and densities of

03 CHe (CIz) =CZ nu-Li 0P=CH(CH2)3CH =CH2



the tw/o triones are very similar and each takes up three moles of

hydrogen when hydrogenated over Adam's catalyst. The infrared

spectra of the two isomorrs are almost identical, vwith the most

significant difference being a strong band at 965 cm. present in

the material obtained via the T.ittig reaction and absent in the other.

The 965 cm"' band is known to be assignable to the C -H out-of-plane

deformation vibration for disubstituted ethylenic structures having

the trans configuration. 57 Furthermore, it is known that the Ttittig

reaction favors the formation of the trans olefin, whereas acid

hydrolysio of the cyclic acetal precursor to pentadlenal should favor

production of the cis olefin.56 It was established by gao-liquid

chromatography that the isomers were each produced in a

geometrically pure otatc. This appears to be the first instance

where the pure trans olefin has been isolated from a tVittig reaction.

A possible rationalization of this observation lies in the fact that the

conditions of low temperature and short condensation time under

which the triene was prepared in this work favor formation of the

most Idnctically stable product, v'hile the usual conditions of high

temperature and long reflux periods might allow time for some

equilibration between the cis and trans forms.

The nuclear magnetic resonance spectra of the two isomers

produced some anomalous data which should be noted here. In the

case of the cis isomer the peak area ratio for apz to sp3 bonded

hydrogen was found to be 4:3 in agreement with theory. The same

ratio for the trans isomer, however, was found to be 1:1. In the

latter case, a search for -CH3 resonance was unsuccessful, thus

ruling out the possibility of double-bond rearrangement to an internal

position. Cyclic structures are ruled out on the basis pf quantitative

hydrogenation results, leaving no other obvious choice than to assign

to this compound the structure of trans-1,3, 8-nonatriene.

A third method for producing 1,3, 8-nonatriene was tried

withe;t success, but the results are sufficiently interesting to be

included in this discussion; An attempt was made to produce the

desired triene by pyrolysis of 3-acetoxyl, 8-nonadiene at 450o0 The

pyrolysate turned out to be a three component mixture of hydrocarbons

which could not be separated with available distillation and

preparative gas-liquid chromatographic columns. The components

were separable on an analytical Carbowax ZOM-packed gas-liquid

chromatographic column, making it possible to rctimate the mole

percent composition of the mixture. Two of the components

represented 90% of the mixture and were in a ratio of approximately

2:3. The mixture analyzed for C9H14i gave a molecular weight

value of 122, and took up one mole of hydrogen when hydrogen-

ated over Adamis catalyst. A nuclear magnetic resonance

spectrum of the mixture gave a ratio of sp2 to sp3 bonded

hydrogen of 6:1 in good agreement with the quantitative hydrogenation

results. At this point the investigation of this rather unusual reaction

was discontinued, although from the data which was obtained it would

appear that the pyrolsate is a miatture of bicyclic compounds. The

two most likely compounds are bicyclo(3. 3. l)-*2nonene and

tetrahydroindan both of which could reasonably be formed by an

internal Diels*Alder reaction of 1,3,8-nonatriene in the vapor phase.

Syntheses of the styrene derivatives for this study were

accomplished via the following sequence of reactions.

CH=C- CH3 N-bromosuccinimide CH= C -CHBr
0 0

CHI=C-CH2Br + RPJM r --- CH= C-CHgR
0 0


Preparation of the intermediate 2*phenyl-*3-bromnopropene

was performed according to the method of Hatch and Patton8 and

was found to be contaminated with 0-bromo-ca-methylstyrene.

Pines, Alul and Kalobelsdi59 have studied this same reaction and

have described the isolation and identification of the impurity. In

this work no attempt was made to remove the p-bromo- a-methyl-

styrene because it involved a rather tedious and uneconomical process

using large scale column chromatography. The subsequent coupling

reactions with Grignard reagents using the impure allylic halide

were not hampered except for lowering of the yields. The final

products were obtained in good purity by careful fractionation of the

crude materials and selection of the fractions with the aid of

gas-liquid chromatography and index of refraction measurements.

B. Results and Discussion

Data for the ultraviolet absorption spectra of cis- and trans-

1, 3, 8-nonatriene are found in Table Z and the spectra are shown in

Figure 1. The calculated absorption maxima were determined

according to Woodward's Rule60 61 for the prediction of ultraviolet

absorption maxima of alkyl-substituted butadienes. Taking butadiene

as the standard with a maximum of Z17 millinicrons, the calculated

maxima are determined by adding five millimicrons per alkyl

substituent. Many examples of the excellent agreement between

calculated and observed values may be found in the monograph on

ultraviolet absorption spcctroscopy by GUlam and Stern. 62 Included

in Tablo 2 are several selected examples reported in the literature

which serve as comparators for the compounds studied in this work.



imas max.
Compound Calcd. Obs. x 104 Reference

Piperylene 222 223.5 2.30 63

Isoprene 222 222 2.39 64

Myrcene 222 224.5 1.70 65,66

ci 4, 3, 8-Nonatriene 222 225.5 2.03

trans-l3 3, 8-Nonatriene 222 227 2.10

a.~ All ~ dat were- deemie In ethano exep for

a. All data were determined in ethanol except for
isoprene which was determined in hexane.

b. Wavelengths are in millimicrons.


4.0 \

trans -------\
3. 8 -

t 3.6




trans ------

210 220 230 240
Wavelength (millimicrons)

Figure 1. Ultraviolet Absorption Spectra of cis
and trans-1,3, 8-Nonatriene in Ethanol

Myrcene and the cis and trans isomers of 1,3,8-nonatriene

all exhibit a distinct departure from VToodward's Rulc in their

absorption of ultraviolet radiation. In the case of myrcene the

departure is small and amounts to a bathochromic shift of only

2.5 millimicrons. It is significant, however, that Marvel and Hwa67

have reported polymerizing this compound by boron trifluoride

initiation to a soluble, apparently cyclic polymer. In the cases of

cis- and trans-l, 3,8-nonatriene the shifts amount to 3.5 and 5.0

millimicrons respectively. The trans isomer has been polymerized

in this work (see Chap. IIl) by a Ziegler catalyst initiator to yield

a polymeric product approximately half of which is soluble and

exhibits the properties expected for a cyclic polymer.

Proceeding now to the styrene derivatives, it can be seen

from Table 3 that two effects seem to be operative in their light

absorption properties. A marked steric effect is observed when

comparing styrene and a-methylstyrene in that a hypsochromic

shift of the so-called K-band for styrene is produced when the a

position is substituted with a methyl group. When the bulk of the

group is increased by extension to n-pentyl the magnitude of the

shift is correspondingly increased. The nature of this steric effect

is fully discussed in the literature,50 6Z so it Is sufficient to say here

that it arises because of the tendency for the bulky a. substituents to





a -Methylstyrene


2-Phenyl-1, 5-hexadione

2,5-Diphenyl-1, 5-hexadienc










K. banda








E x 104










51, 69

510 69

a. Wavelengths are in millimicrons.

-- --


force the olefinic carbon atoms out of coplanarity with the aromatic


The second effect is more subtle in that it manifests itself

only in the intensities of the maxima and not in their location. In

going from 2-phenyl-l-hexene to 2-phenyl-l, 5-hexadiene and

2, 5-dlphenyl-l,5-hexadiene, the intensities of the K-band increase

when the spectra are measured in ethanoLI In the non-polar solvent,

isooctane, there is almost perfect additivity. Since this trend in

the intensities is roughly in the same order as would be expected for

the tendencies of these models to cyclopolymerize, it is felt that

the data does hold some significance. Since the magnitude of the

absorption intensities are, at least to a degree, dependent upon the

polarity of the excited state,68 it seems conceivable that any effect

which tends to enhance this polarity (such as an interspacial

interaction of the absorbing chromophore with a neighboring

chromophore) might also enhance the intensity. That this effect is

observed in a solvent with a high dielectric constant and not in

isooctane might be expected if the effect arise purely from the

polar condition of the excited state.

The spectra obtained for the styrene derivatives prepared

in this work are presented in Figure 2.

4. /

3. 77

o \

3. 5

3. \

2,5-Diphenyl-1,5-hexadiene \

2-Phenyl-1, 5-hexadiene -----

230 240 250 260
Wavelength (millimicrons)

Figure 2. Ultraviolet Absorption Spectra of Styrene
Derivatives in Ethanol

In the methacrylate series it is again seen that the spectral

data follow the same trend that would be expected for the tendencies

of the models to undergo cyclopolymerization. A bathochromic

shift of the maximum with methacrylic anhydride is observed and a

slight enhancement of the extinction coefficients is seen to occur

in going from the monoolefin to the diolefins. The spectral data for

the methacrylate models are shown in Table 4 and the spectra are

presented in Figure 3,

It is felt that the spectral data shown and discussed above

are significant evidence for the unconjugated electronic interactions

proposed by Butler30 as an explanation for the propensity of certain

unconjugated diolefins to undergo cyclopolymerization. The

bathochromic shifts and enhanced absorption intensities all follow

a pattern which would be expected for such electronic effects.

The data may also be taken as further evidence against the hyper*

conjugative interpretation of non-additive light absorption discussed

in Chapter I. If one compares the data for piperylene with that for

1,3,8-nonatriene, for example, the hyperconjugation theory fails

to correctly predict which model will absorb at the longer wave-

length. In the cases of the methacrylate and styrene models, where

hyperconjugative influences are more or less constant, marked

deviations from additivity are still observed.




Compound ax.x x10

Ethyl nethacrylate 206 0, 7Z

Allyl methacylate Z05 0 85,

-lethallyl methacylate 204. 5 0 95

1.1ethacrylic anhydride ZO 1.50

a. Wavelengths are in mnillmicrons,

4. 1

3. 9

3. 7 / \

// ;\\
// \ \

3.5 -

./ \\
3. / 3\

I I -I I
Methacrylic anhydride

200 210 220 230
Wavelength (millimicrons)

Figure 3. Ultraviolet Absorption Spectra of
Methacrylate Derivatives in Isooctane


In the styrene serilo of models the departures from additivity

are admittedly small and it may be argued that too much significance

is being attached to them. If the data for this series is taken by

itself, such an argument might seem just, but in view of the data

for the other models it is felt that the results are significant in that

they fit the general trend seen in all of the spectral results. The

weakness of the effect in the styrenes may arise partially from the

fact that interaction is between 1,5 situated olefinic bonds rather

than 1,6, The phenomenon of cyclopolymerization is likewise more

pronounced when the olefinic bonds are 1,6.

All things thus considered, the data discussed above are

taken to mean that in diene systems where the double bonds are

situated 1,5 or 1,6 with respect to one another, the Tr systems may

interact intramolecularly. The chemical consequences of this

interaction and the attending stabilizing effect are revealed in the

phenomenon of cyclopolymerisation. In view of Winstein's42,43,45

studies in non-classical carbonium ion systems it is believed that

this effect is either peculiar to the excited (or activated) state of

the reacting molecules or to the radical or ionic transient

intermediates produced during the propagation step of the polymeri-

zation. An illustration of these two possibilities is shown below for

a radical propagated reaction.



___ ^'^


R--7 0'

R* +

R --

In the first case the propagation may be considered as

occurring via a stepwise process with intramolecular reaction favored

over the intermolecular, thereby leading to ring closure and hence

the cyclic recurring unit, In the second case the propagation may be

considered as a concerted mechanism leading to cyclic product

completely exclusive of an intermolecular competing step. No data are

available at the present time with which to distinguish between these

two possibilities.

Re +

C. Experimental

Source and Purification of Materials. Ethylene oxide, allyl

bromide, vinylmagnesium chloride, 5-hexen-1-olS and triphenyl

phosphorus were obtained from Peninsular Chemrnesearch,

Incorporated. The allyl bromide was distilled before use and the

vinylmagnesium chloride, which was obtained as an approximately

3.5 molar solution in tetrahydrofuran, was analyzed for concentration

by the double titration method.

Dihydropyran was obtained from the Chemicalo Division

of The Quaker Oats Company and was used as received.

Tetrahydropy ran- 2-methanol and ac rolein vierc obtained

from Carbide and Carbon Chemicals Company. The tetrahydropyran-

2-methanol was distilled before use and the acrolein was used as


Acetyl chloride, a-methylstyrene, and N-brornosuccinimide

were obtained from the Distillation Products Industries division of

Eastman Kodak Company and were used as received.

n-Propyl bromide was obtained from Columbia Organic

Chemicals Company and was distilled before use.

Allyl methacrylate, ethyl methacrylate, and methacrylic

anhydride wvere obtained from Monomer-Polymer Laboratories,

Chemicals Division, Borden Company. Gas chromatography indicated

these compounds to be sufficiently pure for ultraviolet spectral


Equipment and Data. Temperatures reported in this paper

are uncorrected and are recorded in degrees centigrade.

Infrared data were obtained with a Perldn-Elmer Infracord

Double-beam Infrared Recording Spectrophotometer or a Perkin-Elmer

Model 21 Double-beam Infrared Recording Spectrophotometor.

Ultraviolet data were obtained with a Bausch and Lomb

Spectronic 505 Double-beam Recording Ultraviolet-visible

Spectrophotometer equipped with an IP28 photomultiplier and an

air-cooled hydrogen lamp-tungsten lamp combination light source.

Gas-liquid chromatographic analyses were made with a

Wilkens Aerograph Model A-10O-C Gas Chromatographic Instrument

using helium for the eluent gas. Unless otherwise indicated, gas

chro-matographic analyses were made on a five foot column packed

with 20j Silicone GE SF-96 on fire brick. (Reference to this

technique is abbreviated G. L. C. in this paper.)

Nuclear magnetic resonance data were obtained with a

Varian V-4302 High Resolution INuclear Magnetic Resonance


Elemental analyses were performed by Galbraith Laboratories,

KnoxvilUe Tennessee.

Synthesis of 1-Bromo-3-butene. 3*Buten-l-ol was

prepared in yields of 60-70% from vinylmagnesium chloride and

ethylene oxide according to the method of Ramsden, t al. 70 and

converted to the bromide in 55% yield by the general method of

Gaubert, Linstead, and Rydon.71 B.P. 96-99, nZ 1.4652, lit. b.p.

98.5-990, n0 1.4621.

Synthesis of 2,4-Pentadienyl Chloride. 2,4-Pentadienyl

chloride was synthesized in six steps by the method of Woods and

Lederle54 as modified by Crombie, Harper, and Thompson. 55

B.P. 46-470/54 mm., n12 1.4951, lit. 55 b.p. 80-820/240 mm.,

nZ0 1.492-1.493.

Synthesis of cio-l,3, 8-Honatriene. The Grignard reagent

of l-bromo-3-butenc was prepared in the usual way by adding a

solution of 20 g. (0.15 mole) of the halide in 35 ml. of absolute

ethyl ether to a mixture of 3,5 g. (0.14 atoms) magnccium. sand

and 25 ml. of absolute ethyl ether. A solution of 10.0 g. (0.10 mole)

2,4-pcntadienyl chloride in 25 ml.! of absolute other wvas then added

dropwise to the stirred Grignard solution at such a rate as to cause

gentle refluxing of the ether. Shortly after addition of the chloride

was completed the reaction mixture became a slurry and was heated

to a gentle reflux for 30 min. longer. The mixture was then cooled

in an ice water bath and decomposed by careful addition of chilled

dilute hydrochloric acid until all of the solid material was dissolved.

The ethereal layer was separated the aqueous layer extracted with

25 ml. of ether and the two ethereal portions combined. The ether

solution of crude product was washed with 10. sodium bicarbonate

solution and distilled water and dried over anhydrous sodium sulfate.

The ether was removed by distillation and the residual liquid was

distilled at reduced pressure through a 23 plate pinning band column.

The fraction collected at 65-670/41 mm. was refractionated to

yield 3.0 g. (25%) of the desired product b. p. 65-670/41 mm.,

n20 1.4694, D20 0.891. The compound, which was found to be 99 -t

pure by G. L.C. analysis, took up 3.18 moles of hydrogen per mole

of sample. The infrared spectrum had the following absorption

bands assignable to the proposed structure:57 1640 cm. "

(C=eC, non-conj.), 1000 cm.'1 ( -CH=CHZ), 913, 900 cm."1

( -CH=CH2), An N. M. R. spectrum of the compound gave an

integrated peak area ratio for sp2 to sp3 hydrogen of 4:3. Data on

the ultraviolet spectrum are found in Table 2 and the spectrum in

Fig. 1.

Anal. Calcd. for C9H14: C, G88.45; H, 11.55.

Found: C, 88.26; H, 11.39.

Synthesis of l-Bromo-5-hexene. l-Bromo-5-hexene was

prepared essentially as described by Butler and Price72 with the

following modifications. The 2-chloromethyl tetrahydropyran was

prepared according to the procedure of Crombie metal. 73 and the

5-hexen-l-ol was converted to the alkenyl bromide by the general

method of Gaubert, Linstead, and Rydon. 71 (5-Hexene-l-ol

purchased from Peninsular ChemResearch, Xncorporated was also

used in this synthesis.) With these modifications the yields

reported by Butler and Price were improved by approximately

two-fold (50-60%) and the general method was considerably

simplified. The product had b. p. 460/14 mm., n3 1.4640, lit.

b.p. 76-780/45 mm., n5 1.4630.

Synthesis of 5-Hexenyltriphenylphosphonium Bromide. *

A 500 ml. resin kettle was charged with 105. 6 g. (0. 65 mole)

l-bromo-5-hexene, 170 g. (0.65 mole) triphenyl phosphorus, and

200 ml. of anhydrous xylene and the resulting solution was stirred

and refluxed for 10 hr. The mixture was then allowed to cool to

room temperature at which time a lower viscous layer of liquid

developed and became semi-solid on standing. The supernatent

liquid was poured from the kettle and the vessel was evacuated with

a water aspirator and heated to drive off most of the remaining

xylcne. The kettle was then evacuated with a vacuum pump and

heated to remove the last traces of xylene after which the crystalline

residue was pulverized, washed with benzene and vacuum dried in a

desiccator over phosphorus pentoxide. The yield of crystalline

phosphonium salt was 237 g. (86%) and had a m. p. 160-162.

The infrared spectrum of the salt agreed very closely with that of

allyltriphenylphosphonium bromide, a known compound.56

Anal. Calcd. for C24H26BrP: C, 67.88; H, 6.17; Br, 18.84;

P, 7.09. Found: C, 67.33; H, 6.06; Br, 18.91; P, 7.34.

Synthesis of trans-1, 3,8-Nonatricne. The procedure for

the preparation of this compound is essentially that devised by

Hauser and Raymond. 74 A stirred slurry of 42.4 g. (0. 10 mole)

5-hexenyltriphenylphosphonium bromide in 200 ml. of absolute

ethyl ether in a dry nitrogen atmosphere was treated with 85 ml.

of an approximately 15% solution of n-butyl lithium in hexane. The

resulting deep orange solution of the triphenylphosphorus-5-

hexenylide was cooled to 100 by means of an ice water bath and a

solution of 6.7 g. (0.12 mole) acrolein in 25 ml. of absolute ethyl

ether was added over a 30 sec. period followed 15 sec. later by

100 ml. of 2 molar ammonium chloride and finally 100 ml. of

water. Addition of the acrolcin caused discharge of the orange

color and formation of a fine white precipitate. Upon addition of

the ammonium chloride solution and the water, the precipitate

went into the aqueous layer as a gummy v'hite mass. The liquid

layers were poured away from the solid, separated and the aqueous

layer was extracted with 50 ml. of ether. The solid phaeo of

phosphine oxide and lithium bromide was washed with 50 ml. of

ether and the washings combined with the original organic layer and

the ether extract. The combined cthercal portions wore then dried

over anhydrous sodium sulfate, filtered and inhibited with 0. 2 g.

of hydroquinone. The ether and hexane were distilled through a 30

cm. vacuum-jacketed Vigreux column until the pot temperature rose

to 700. The remaining liquid was then distilled through a 23 plate

spinning band column under reduced pressure to yield 2.0 g. of a

clear, colorless liquid b.p. 68-690/43 mm., 20 1.4721, D20 0.771.

G. L. C. analysis of the product revealed only one

component and quantitative hydrogenation resulted in a hydrogen

uptake of 3.00 moles per mole of sample. The infrared spectrum of

the material showed the following bands assignable to the proposed

structure:57 1640 cm.,' (C=C, non-conj.), 1595 crn.'1 (C=C C=C),

999 cm."1 ( -CH=CH2), 965 cm.1" ( =C -, trans), 900 cm. '

( -CH=CH2). An N.M.R. spectrum of the compcu'd gave an

integrated peak area ratio for sp2 to Ep3 hydrogen of 1:1. G. L. C.

analysis of a mixture of this triene and that prepared by the Grignard

reaction showed two narrowly spaced peaks. Data on the ultraviolet

spectrum are found in Table 2 and the spectrum in Fig. 1.

Anal. Calcd. for C9H14: C, 88.45; H, 11.55.

Found: C, 00.36 H, 11.77.

Synthesis of 1, 8-Nonadien-3-ol. The procedure for the

preparation of 1, 8-nonadien-3-ol is essentially that devised by

Nazarov and Kakhniashvil75 for the reactica of Grignard reagents

with a, B* unsaturated carbonyl compounds. The Grignard reagent

of 1-bromo-5-hexene was prepared in the usual manner by the

addition of a solution of 325 g. (2. 0 moles) of l-bromo-5-hc::cno in

300 ml. of absolute ethyl ether to 73 g. (3.0 g. atoms) of magnesium

turnings in 500 ml. of absolute ethyl cther. V;'hen addition of the

halide was completed and spontaneous refluwdng of the ether ceased,

the mixture was heated to a gentle reflux for two hr. longer. A

solution of 95 g. ( 17 moles) acrolein in 950 ml. absolute ethyl

ether was then added dropwise to the Grignard solution over a

period of 10 hr. The resulting mi:ture was stirred for approximately

10 hr. at room temperature, cooled in an ice vrtcr bath and

decomposed carefully with just enough dilute hydrochloric acid to

dissolve all colids. The ethereal layer was separated, the organic

layer extracted once with 100 ml. of ether and the combined ethereal

portions dried over anhydrous magnesium sulfate. The cther was

then removed under vacuum in a flash evaporator and the residual

liquid fractionated through a 30 cmo vacuurn-jacheted Virgre : column

to yield 134 g. (56%) of the alcohol, b.p. 83-860/10 mm., n3 1.4545.

G. L C. analysis showed the material to be 99+ pure and the

infrared spectrum agreed with the expected structure.

Anal. Calcd. for C9H160: C, 77.09; H, 11.50.

Found: C, 77.30; H, 11.69.

Synthesis of 3-Acctoxy-l, 8-nonadieno. A solution of

134 g. (0.96 mole) 1,8-nonadien-3-ol, 103 g. (1.30 moleo)

anhydrous pyridino, and 300 ml. of absolute ethyl ether was

maintained at 00 by an ice vrater bath and to it was added dropwise

94 g. (1.2 moles) of acetyl chloride. The resulting slurry was

stirred for 9-10 hr. at room temperature and then poured over

cracked ice. The ether layer wan separated and the aqueous layer

extracted with ether, The combined ether layer and ether extract

vwac w'ashcd with dilute hydrochloric acid, and saturated sodium

bicarbonate solution and dried over anhydrous sodium culfate. The

theor was removed under vacuum with a flash evaporator and the

residual liquid distilled through a 30 cm. vacuum-jacklted

Vigreu:: column at reduced pressure. The yield of ester was 142 g.
2 S
(81%), b.p. 62-640/1 mm.. nD 1.4405. The product was found

by G, L.C. analysis to be 99+% pure and the infrared spectrum

agreed with the expected structure.

Anal. Calcd. for C IH 102: C, 72Z49; H, 9.96.

Found: C, 72.51; H, 10.13.

Pyrolysis of 3-Acetoxy-l, 0-nonadienc. The apparatus

employed for ester pyrolysio is essentially that described by Bailey

and King.76 In a typical run 36.4 g. (0. 20 mole) of 3-acetoxy-1,8-

nonadicnc was dropped at the rate of 1.0 g. per min. into the pyrolysis

tube at 450 + 5 with an external nitrogen flow rate of 40 ml. per

min. When all of the ester had been discharged from the addition

funnel the furnace was allowed to cool to room temperature and the

cracking tube washed down with ethyl ether. The pyrolysate was

then recovered from the cold traps, combined with the ether

washings, and washed free of acid with 10% sodium bicarbonate

solution and finally with distilled water. The ethereal pyrolysate was

dried over anhydrous sodium sulfate, the ether removed by distillation,

and the residual hydrocarbon mixture distilled under reduced pressure

through a 23 plate spinning band column. A 12. 8 g. fraction b. p.

63-67/25 mm. was collected in addition to 6. 3 g. of uncracked ester

for a material balance of 70%. G.L. C. analysis with a 10 ft. 1/4 in.

diameter column packed with 20% Carbowax 20M on fire brick revealed

the product to be a mixture of two components present in an integrated

peak area ratio of 2:3. Upon quantitative hydrogenation the mixture

took up 1. 13 moles of hydrogen per mole of sample based on the

assumption that the two components are isomers. A cryoscopic

molecular weight determination in benzene gave a value of 122 vs.

a calculated value of 122. The nuclear magnetic resonance spectrum

showed the ratio of sp2 hydrogen to sp3 hydrogen to be 1:6.

Anal. Calcd. for C9Ht4: C, 88.45; HI, 11.55,

Found: C, 88.59; H, 11.54.

Attempts to carry out the pyrolysis at lower temperatures

resulted in smaller conversions of the ester and greater complexity

of the pyrolysate.

Synthesis of 3-Bromo-2-phenylpropcne. Preparation

of 3-bromo-2-phenylpropene was accomplished via the

N-bromosuccininnide bromination of a-methylstyrene according

to the procedure of Hatch and Patton. 58 The product had the

physical properties reported by these authors, but was contair.inated

with B-bromo-* -methylstyrene as was found by Pines, et al. 59

in their studies of this reaction. G. L. C. analysis with available

columns failed to resolve the two halides so an estimation of purity

was not possible. The impure product was, however, successfully

used to prepare desired model compounds in low yields. The

properties of the impure product used in this work were b. p.

89-910/5 mm.. n 1.5869, lit.58 b.p. 900/5 mm., n .0 1.5369.

Synthesis of 2-Phenyl- -hex3eno. The Grignard reagent

of n-propyl bromide was prepared in the usual manner from 27.6 g.

(0.23 mole) of n-propyl bromide in 30 ml. of absolute ethyl ether

and 1 g. (0. 21 g. atom) of magnesium turnings in 45 ml. of

absolute ethyl ether. A solution of 29.6 g. (0.15 mole)

3.bromo-Z-phenylpropene in 30 ml. of absolute ethyl ether was then

added dropwise to the Grignard solution at a rate such as to cause

gentle refluxing of the ether. When addition of the allylic halide

was complete the resulting mixture was refluxed overnight, cooled

in an ice water bath and decomposed by cautiously adding dilute

hydrochloric acid. The organic layer was separated, the aqueous

layer extracted with ether and combined organic layer and ether

extract washed free of acid with l07' sodium bicarbonate. The

ethereal product was then washed vith water, dried over anhydrous

sodium sulfate and the ether removed under vacuum with a flash

evaporator. The residual liquid was then distilled under reduced

pressure through a 23 plate spinning band column to yield five

fractions boiling from 830/8 mm. to 900/8 mm. totaling 12 g.

(50T7) in weight. Each of the fractions was found by G. L. C. and

index of refraction measurements to be slightly contaminated with

P-bromo- a-methylstyrene. Redistillation of the middle fractions

yielded a 1.0 g. fraction of analytical purity, b.p. 89-900/10 mm.,

n 1.5254. The ultraviolet spectrum is shown in Fig. 2 and other

data in Table 3.

Anal. Calcd. for C12H16: C, 89.94; H, 10.06.

Found: C, 89.96; H, 10.10.

Synthesis of 2-Phenyl-1, *5hexadiene. The preparation of

2-phonyl-1, 5-hexadiene was accomplished according to the method

of Pines, et al. 59 The product was obtained in analytical purity as

described for Z-phenyl-l-hexene, and had a b. p. 89-900/9 mm.,

nj0 1.5361, lit.59 b.p. 1040/10 mm., n0 1.5314. 17hile the rather

large discrepencies in physical properties noted here raise a

question as to the purity of the sample, G. L. C. analyois as well

as infrared and elemental analysis indicate the sample prepared in

this work to be of high purity. The ultraviolet spectrum is shown

in Fig. 2 and other data in Table 3.

Anal. Calcd. for C1H14: C, 91.03; H, 8.92.

Found: C, 90.91; H, 8.68.

Synthesis of 2,5-Diphenyl-1,5-hexadienc. A solution of

59 g. (0.3 mole) 3-bromo-2-phcnylpropen in 150 ml. absolute

ethyl ether was added dropwise to a stirred mixture of 5.8 g.

(0.15 g. atoms) magnesium turnings in 50 ml. of absolute ethyl

other over a period of 2 hr. The resulting mixture was then treated

with 0.9 g. of anhydrous cobalt chloride77 causing a mildly exothermic

reaction which kept the ether refluxing for approximately 30 min.

The resulting black-brown mixture was then refluxed for two hr.

after which it wao cooled in an ice water bath and decomposed with

dilute hydrochloric acid. The organic layer was csparated and the

aqueous layer extracted twice with 25 ml. portions of ethyl ether. The

combined organic layer and ether extracts were washed with 10%

sodium bicarbonate and water and dried over anhydrous sodium sulfate.

The ether was then removed under vacuum in a flash evaporator and

the dark brown residual oil distilled at reduced pressure. After a

forerun of volatile materials, a fraction came over at 150-160/1 mm.

%vhich crystallized upon cooling. The solid material, 2* 8 g. (8.3%)

was crystallized four times from methanol to afford a white crystalline

product which had a m. p. 48.5-49. 0, lit. 53 m. p. 51.0-51.30. The

infrared spectrum of the product agreed with that reported by

Marvel and Gall53 and G. L. C. analysis showed only one peak. The

ultraviolet spectrum is shown in Fig. 2 and other data in Table 3.

Anal. Calcd. for C18H18: C, 92.26; H, 7.74.

Found: C, 92.42; H, 7.94.

Synthesis of Methallyl Methacylate. Methallyl

methacrylate is commercially available at relatively low prices,

and was synthesized in this work merely to expedite the study. The

ester was prepared from methacrylic anhydride and methallyl alcohol

in the usual manner and was fractionated through a 23 plate spinning

band column to obtain an analytically pure sample, b. p. 580/15 mm.,

nD 1.4415. lit. b.p. 630/17 mm., n0 1.4400. The ultraviolet

spectrum is shown in Fig. 3 and other data in Table 4.




A. The Polymerization of 1,3,8-Nonatriene

1,3, 8-Nonatriene is a monomer which is unique in that it

is potentially capable of undergoing cyclopolymerization by a

cumulative 1,2 and 1,4 addition during the propagation stop or

cstps. Marvel and Hwa67 have already reported observing ouch a

phenomenon in the boron trifluoride initiated polymerization of

myrcene which is shown below.

+ I I %C.


--C-C C C


Ce C


C C-C-c
BF3-C- C C

As it turns out the resulting polymer has the same structure
as one reported by Robert. and Day which was produced by the



aluminum chloride initiated polymerization of p-pinene. The

cationically initiated polymerization of B-pinene which was studied

by the latter authors is shown below.

HAlC13 A1C13--- H2C
A1C13 ---- 3


-C- -Ce
C n C

The polymerization of 1,3,8-nonatriene was successfully

accomplished in the case of the trans isomer by employing the

Ziegler-type initiator system, titanium tetrachloride-triethylaluminum.

Two attempts to polymerize the cis isomer under conditions

equivalent to those employed for the trans form resulted in

approximately 10% conversion to insoluble polymer. Polymer-

ization of the trans isomer afforded a 20% conversion to

polymer approximately half of which was benzene-soluble.

No attempt was made to learn the optimum conditions for carrying

out the polymerizations. A comparison of molecular models of the

cis and trans isomers of 1,3, 8-nonatriene does not give any

indication as to why the trans form should polymerize any more

readily than the cis. There seems to be no reason why under

appropriate conditions the cis isomer could not give a good conversion

to polymer.

The soluble portion of the material obtained by polymerizing

1,3, 8-nonatriene has an infrared absorption spectrum which clearly

agrees with the structure which would be expected for a cyclic

product. The overall reaction is shown below.

S Al(CzHs ,)3

A band at 1650 cm. in the infrared spectrum is assignable

to the residual double bond and a strong band at 965 cm. "I is

assignable to the trans configuration about that bond. 57 molecular

models of the recurring units show that the trans configuration gives

the least amount of steric crowding in the system and allows complete

freedom of rotation about the carbon-carbon bonds adjacent to the

ring, while the cis form produces just the opposite condition. In the

cis form the rings must fold back on one another for ring closure to

occur in adjacent units producing a highly crowded condition which

would probably act to inhibit ring formation.

The absence of terminal unsaturation in the soluble polymer

was evidenced by the absence of an infrared absorption band in the

1000 cm. region and only a weak band in the 900 cm. -1 region.

These bands which are highly characteristic of terminal unsaturation 57

were present in the monomer as well as in all of the other terminal

olefins prepared in this work.

B. Experimental

Source and Purification of Materials. Titanium

tetrachloride was obtained from Peninsular ChemResearch,

Incorporated and was distilled before use.

Triethyl aluminum was obtained as a 25% solution in

heptane from Hercules Powder Company and was used as received.

The preparation and purification of 1, 3, 8-nonatriene is

described in the experimental section of Chapter II,

Solvents and other materials were obtained from stock.

Equipment and Data. Intrinsic viscosity measurements

were made with a Cannon-Ubbelohde semi-micro dilution viscometer.

Other information on equipment and data are given in the

experimental section of Chapter Il.

Attempted Polymerizations of cis-1, 3, 8-Nonatricne. A

small serum capped vial was charged by means of a micro*

hypodermic syringe with 0. 0028 g. (0.07 millimrle) of titanium

tetrachloride and 0.08 ml. of heptane containing 0.013 g. (0. 11

millimole) of triethyl aluminum in a dry-box under a dry nitrogen

atmosphere. The vial was further charged with 1.0 mL of high

purity hexane and 0.61 g. (5 millimoles) of the tricnc, slaken vwll,

and allowed to stand at 250 in the dry-box for a period of 72 hr. The

mixture was then poured into methanol, filtered on a scintered glass

dic and the residue washed with methanol. The residue was a

tough plastic substance which could not be ground up. The material

was placed in a soxhlet extractor and extracted for two days with

hot benzene. The bcnzene extract was then poured into methanol

causing less than a milligram of colid to be precipitated. The solid

which was recovered from the e::traction thimble and dried appeared

unchanged. A second attempt to polymerise thio monomer at a

concentration of 10% in he:rane gave essentially the same results.

The crosslinkcd material which was insoluble in several organic

solvents was obtained in the amount of 0.05 g. (8.5%) and was not

investigated any further.

One attempt was made to polymerize this mnonomer in bulk

with 0. 1% azo-bis-iabutyronitrilo and was not successful after one

week at 80.

Polymerization of tran1,, 3, 8-Nonatriene. A ocrevcap vial

vwa charged by means of a micro-hypodermic Gyrineg with 0.056 g.

(0. 15 millimole) titanium tetrachioride, 0. 08 ml. containing 0. 013 g.

(0. 11 millimole) of triethyl aluminum and finally with 3. 6 ml. of

high purity hex:ane and 1.0 g. (8 millimoles) of trans_-1,3,8-

nonatrienc. All of the operations were carried out in a dry-box under

an atmosphere of dry nitrogen.. The mixture was shaken well and

allowed to stand for 40 hr. at 250 after which it was decomposed by

pouring into methanol, The gclatinous material was filtered off,

washed with methanol and allowed to stand in dry benzena for 10 hr.

vith occasional vigorous agitation. The remaining undissolved

polymer was then filtered off and the filtrate poured into methanol to

afford 0.1 g. of clear colorless tacky polymer which after a second

precipitation from benzene into methanol had a flow temperature of

50-550 and an intrinsic viscosity of 0, 15. The insoluble material,

which was a soft rubbery substance, weighed 0. 13 g. for a total

conversion of 23%. An infrared spectrum of the soluble polymer

(run as a film pressed out from the melt) had the following absorption

bands. 2950 cm. *1, strong, broad; 1650 cm.*l weak; 1450 cm.1

strong; 1380 cm. ", strong; 1070 cm.*", weak; 965 crm.- strong;

910 cm. ", weak.

Anal. Calcd. for C9H14: C, 88.45; H, 11,55.

Found: C, 83.86; H, 9.81; Ash, 1.8 (?).



Three series of compounds which are derivatives of

(1) butadiene, (2) styrene, and (3) methacrylic acid have been

studied spectrophotometrically in the region of the ultraviolet

spectrum extending from 190 to 270 millimicrons. The methods of

synthesis and properties of the butadienes and styrenes have been

described in detail.

The butadiene derivatives which were studied were the

cis and trans isomers of 1,3, 8-nonatriene. The ultraviolet

absorption maxima for these two isomers were shifted bathochromically

from the position which would be calculated by Woodward's Rule60 61

for predicting the maxima of acyclic alkyl-substituted butadienes.

The styrene derivatives studied were 2-phenyl-l-hexene (1),

2-phenyl-, 5-hexadiene (II), and 2, 5-diphenyl-1, 5-hexadiene (III).

The absorption maxima for these compounds vere essentially

identical, although in a polar solvent the absorption intensities

increased in the order I < I
The compounds studied in the methacrylate series were the

ethyl, allyl, and methallyl esters of methacrylic acid and finally


methacrylic anhydride. In the case of the esters again, the

absorption maxima are in essentially the same location but the

intensities for the diolefins are greater than those for the monoolefins.

The anhydride, on the other hand, exhibits a band which is shifted

bathochromically some five millimicrons from those of the esters.

These data are taken as evidence for unconjugated interactions

of the 1,6 and possibly the 1,5 ethylenic bonds in the excited state.

Such interactions account at least partially for the tendency of

certain 1,5 and 1,6 dienes to undergo polymerization by the

intra-intermolecular mechanism leading to linear saturated polymers. 30

The trans isomer of 3, GC-nonatriene was polymerized vith

a Zieglcr-type initiator to yield a polymer half of which was soluble.

The infrared spectrum of this polymer was compatible with the

structure which would be expected to result frcm cumulative 1,2

and 1,4 additions during the propagation steps of the polymerization.


Additional Data on 1-Alkenyl Substituted Butadienes

In an effort to determine the extent of unconjugated

chromophoric interactions in 1,5-diolefinic systems, 1,3,7-

octatriene was synthesized. The method employed for this

synthesis has yielded what appears to be the pure cis isomer.

The ultraviolet absorption maximum occurs at 225 millimicrons

with an C value of 21,000. These data fit into the general trend

of the data on butadienes discussed in the text (Chap. II, Sec. B).

As would be expected, the 1,5 interaction in 1,3,7-octriene is

somewhat weaker than a 1,6 interaction and the absorption maximum

is correspondingly closer to tdhe value which would be predicted by

Woodward's Rule.60,61

The synthesis and identification of cis-1, 3, 7-octatriene

has resulted in some rather surprising data which should be noted

here. This compound was prepared via the Wittig reaction between

triphenylphosphorusallytide and 4-pentenal, It will be recalled that

trans 1,3, 8-nonatricne was prepared by the reaction of

triphenylphosphorus-5-hexenylide with acrollen. It would thus

appear that by choosing the appropriate aldehyde and ylide one may

synthesize in geometrically pure form either the cis or the trans

isomers of 1-substituted butadienes, If the trans isomer is desired

acrolein would be employed, while if the ciJ isomer is desired the

allylide would be chosen. Bohlmann and Mannhardt80 have reported

observing a somewhat similar instance in their application of this

reaction to the synthesis of tridecal, 3,5, lltetraen-7, 9*dlyne.

WVhere acrolein was used the pure cis configuration about the

3-ethylenic bond was obtained and when the allylide was used a

mixture of the corresponding cis and trans isomers was observed.

No explanation was offered for these rather surprising results.

In this work the cis configuration was assigned to

1, 3 7-octatriene on the basis of infrared data. The strong

absorption band at 965 cm. 1 assignable to the trans configuration

is absent from the infrared spectrum of this material. Furthermore,

the spectrum bears A striking resemblance to that of cis 4 l3,8-

nonatriene the configuration of which has been established in prior

work (see Chap. II, Sec. A). Gas chromatography and infrared

analysis both indicate the material to be pure and free of the trans

isomer. The physical properties of cis *1, 3, 7-octatriene are

b.p. 115-117, n0 1 4594.


Obviously further experiments will be necessary in order

to validate the findings of this study and establish the Generality of

these phenomena. In the event that these reactions prove to be

general for the synthcsir of butadienes vAth 1-alkyl or 1-alkenyl

substituents, a convenient method for the preparation of geometrically

pure cis and trans butadienes vill be available.


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Thomas W. Brooks was born on November 11, 1933 in

Wyandotte, Michigan. He attended public schools in both Michigan

and Florida and was graduated from Manatee County High School,

Bradenton, Florida in 1952. He attended The Citadel, The Military

College of South Carolina, from which he was graduated in 1956

with the degree of Bachelor of Science in Chemistry. In the fall

of 1956 he entered The University of Florida from which he received

the degree of Master of Science in 1959. He has continued his

graduate study at The University of Florida up to the present time.

During his stay at this institution he has held the various positions

of graduate assistant, research assistant, and predoctoral research


The author is a member of Alpha Chi Sigma Chemical

Professional Fraternity and The American Chemical Society,

The author is married to the former Flora Lucretia Smith

and is the father of one child, Lucretia Collette.

This dissertation was prepared under the direction. of the

chairman of the candidate's supervisory committee and has been

approved by all members of that committee. It was submitted to

the Dean of the College of Arts and Sciences and to the Graduate

Council, and was approved as partial fulfillment of the requirements

for the degree of Doctor of Philosophy.

August 12, 1961

Dean, College of Arts dnd Sciences

Dean, Graduate School

Supervisory Committee:


C. c. O A

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TITLE: A study of unconjugated chromophoric interactions related to
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