Alternating Copolymerization of Benzofuran with Crotononitrile and a-Chloroacrylonitrile

JUNJI FURUKAWA,* EIICHI KOBAYASHI,* and SHIRO NAGATA,+ Department of Synthetic Chemistry, Kyoto University, Kyoto 606, Japan

Synopsis

The copolymerizations of benzofuran with a,a- or a#-disubstituted acrylic monomers were studied. The alternating copolymer of benzofuran and crotononitrile was prepared in the presence of an excess amount of crotononitrile with respect to benzofuran, ethylaluminum dichloride, and azobisisobu- tyronitrile. The intrinsic viscosity of copolymers was 0.1-0.2 dl/g. Crotononitrile is known to possess a polar carbon-carbon double bond from 13C-NMR spectroscopy but the alternating copolymeri- zability with benzofuran is low. It was found that the order of alternating copolymerizability of acrylic monomers is as follows:

ClAN > AN > MAN > cis-CrN > trans-CrN

This fact may be attributed to the steric hindrance of the fl-methyl of crotononitrile. The induced shifts by complexation with ethylaluminum dichloride on 13C-NMR spectra of the two isomers of crotononitrile are almost same but the copolymerizability of cis isomer is higher than that of trans isomer.

a-Chloroacrylonitrile shows the highest alternating copolymerizability with benzofuran in the presence of weak Lewis acid such as ethoxyaluminum chloride. Alternating copolymerizability of acrylic monomers seems to be in proportion to their e value. The reactivity of cis- and trans-cro- tononitrile may depend on the nature of a ternary complex composed of aluminum compound, cro- tononitrile, and benzofuran.

INTRODUCTION

Benzofuran (BF) has an excellent cationic polymerizabilityl and a strong donor character, but the alternating copolymerization is not known. We investigated the copolymerizations of BF and various acrylic monomers complexed with Lewis acid catalysts in a series of studies on alternating copolymerizations between multisubstituted olefins and successfully prepared a new alternating copolymer of BF-acrylonitrile (AN) or BF-methacrylonitrile (MAN).2

In this article the copolymerizations of BF with a- or @-substituted AN, that is, cis- or trans- crotononitrile (CrN) and a-chloroacrylonitrile (ClAN), are studied.

Kobuke et al.3 examined the relative reactivities of cis- and trans-CrN and sec- butyl crotonate in anionic homopolymerizations and found that the trans isomers are generally more reactive than the cis isomers, although their reac- tivities are more or less dependent on the type of catalyst and solvent used. The alternating copolymerization of CrN is unknown.

Gaylord et al.4 pointed out that the reactivity of ClAN in the alternating co- polymerization with styrene is inferior to AN and MAN. They proposed that

* Present address: Department of Industrial Chemistry, Science University of Tokyo, 278 Noda,

+ Present address: Central Research Laboratories, Kuraray Co., Ltd., 710 Kurashiki, Japan. Japan.

Journal of Polymer Science: 0 1978 John Wiley & Sons, Inc.

Polymer Chemistry Edition, Vol. 16,2955-2964 (1978) 0360-6376/78/0016-2955$01,00

2956 FURUKAWA, KOBAYASHI, AND NAGATA

the alternating copolymerizability of acrylic monomers is not compatible with e values.

Consequently, the alternating copolymerization of BF with a,a- or a,p-di- substituted monomers is an interesting problem related to the reactivity of monomers in the alternating copolymerization and structure of copolymers.

EXPERIMENTAL

BF was prepared2 from coumarin by the Puson m e t h ~ d . ~ Commercial ClAN was purified by drying over molecular sieves 3A and distilled before use. Commercial CrN is a cis-trans mixture. Each isomer was separated by fractional distillation with a column containing a spinning band. The isomers were iden- tified by 60 MHz lH-NMR spectroscopy; the coupling constants between two olefinic protons were 10.8 Hz for the cis isomer and 16.7 Hz for the trans isomer. The determination of a cisltrans ratio was also done by gas chromatography at 120"C, using a Yanagimoto GCG-550T with a 3 m PEG-column.

Organoaluminum compounds EtnA1C13-, ( n = 1, 1.5, 2) were purified by distillation. Ethoxyaluminum compounds were prepared by the reaction of corresponding EtnA1C13-, with absolute ethyl alcohol and followed by aging over- night.

Toluene for a solvent, Lewis acid, and an acrylic monomer with or without azobisisobutyronitrile (AIBN) were charged successively in an ampoule cooled at -78°C under nitrogen atmosphere. After the mixture was kept standing for several hours a t room temperature it was cooled down to -78°C and BF was added. The copolymerization is conducted at 30°C. The reaction mixture was poured into methyl alcohol that contained a small amount of aqueous hydro- chloric acid and the precipitated polymer was filtered off. The composition of the copolymer was determined by elementary analysis.

(The characterization of the copolymers was made by 220 MHz (Varian HR- 220) or 100 MHz (Varian HA-100) lH-NMR spectroscopy in ds-dimethyl sulf- oxide (d6-DMSO) or deuterochloroform. The viscosity was measured in di- methylformamide (DMF) or chloroform at 30°C.

13CINMR spectra of acrylic monomers were obtained in toluene at room temperature by the continuous wave method with a Varian HA-100 spectrom- eter.

RESULTS AND DISCUSSION

13C-NMR Spectra of Acrylic Monomers Complexed with Ethylaluminum Dichloride

We have shown that 13C-NMR spectroscopy is a useful method of investigating the nature of acrylic monomers complexed with Lewis acid. The nuclear mag- netic resonance (NMR) of the a- and &carbons of AN was shifted upfield and downfield, respectively, by complexation with aluminum compounds, whereas nitrile carbon was scarcely moved. This fact indicates that the polarization of the carbon-carbon double bond is enhanced as acidity and acid strength of the complexing agent increase.6

Table I lists the 13C-NMR chemical shifts 6 of various acrylic monomers with or without an equimolar amount of ethylaluminum dichloride (EADC). The

BENZOFURAN WITH CROTONONITRILE 2957

TABLE I The Shifts of 13C-NMR Spectra of Nitrile Monomers by Complexation with EADC

a t Room Temperature

6 , ppmb Monomep P-C C=N a-C a-CH3 b-CH3 evalue

AN 136.5 117.3 107.8 +1.20= AN-EADC 148.9(-12.4) 117.7(-0.4) 101.7(+6.1) ... MAN 130.2 118.6 118.6 20.1 +0.81" MAN-EADC 137.8(-7.6) 120.2(-1.6) 113.1(+5.5) 18.1(+2.0) . . . cis-CrN 148.9 115.7 101.1 19.0 . . . cis-CrN-EADC 163.8(-14.9) 117.7(-2.0) 95.2(+5.9) 20.5(-1.5) . . . trans-CrN 150.0 117.5 101.6 20.5 . . . trans-CrN- 164.8(-14.8) 118.6(-1.1) 95.2(+6.4) 22.1(-1.6) . . .

ClAN 130.9 114.6 110.7 +1.40d EADC

ClAN-EADC 141.6(-10.7) 113.7(+0.9) 105.8(+4.9) . . .

a An equimolar amount of EADC was added to acrylic monomers in toluene. The values in parentheses indicate the shifts induced by complexation and (+) is upfield

Reference 10. The value was determined by Otsu et al.7

shift.

difference I 6 p C - is supposed to be in proportion to the polarization in the double bond. The order of I 6peC - 6a.cl of complexed monomers agrees with that of the uncomplexed. It is pointed out that the a-substituted group neutralizes the polarity of the double bond, whereas the @-methyl group enhances its po- larization to a remarkable degree. In comparison with chemical shifts of AN the methyl group of the &position induces a downfield shift of @-carbon and an upfield shift of a-carbon. This fact suggests the polarization of the double bond enhanced by hyperconjugation. Cis and trum isomers of CrN exhibit similar behavior in the presence of EADC.

The aluminum compound may coordinate with the nitrile group at a site far from @-methyl, even in the cis isomer, but no ciirect interaction exists between it and the carbon-carbon double bond.

The chlorine at the a-position also lowers the polarity predominantly, thus promoting the upfield shift of the @-carbon, but there is little downfield shift of the a-carbon, perhaps because of the electron-attracting nature of the chlorine atom in cooperation with the conjugated system.

The order of Ibp., - 6a.cl is as follows:

cis-CrN, trans-CrN > AN > ClAN > MAN The e value of monomers, however, may not be a simple function of polarization because that of ClAN is larger but its I 6p-C - &.cl is smaller than AN.

Copolymerization of BF and CrN

Benzofuran possesses cationic polymerizability, whereas CrN has the anionic, but neither monomer has radical homopolymerizability. Copolymerization between them is unknown, however.

Copolymerization of BF and CrN was carried out in the same manner as BF-AN copolymerization.2

Table I1 shows the result of the copolymerization of BF and cis, trans- CrN

2958 FURUKAWA, KOBAYASHI, AND NAGATA

TABLE I1 The Copolymerization of BF and CrN in Toluene a t 30°C

BF (mole/ liter)

0.77 1.54 1.54 0.77 1.54 3.08 5.38

CrNa (mole/ (feed liter) mole %)

1.53 66.6 3.07 66.6 3.07 66.6 3.07 79.9 3.07 66.6 3.07 49.9 3.07 33.9

Catalyst" (mole/ liter)

EADC 1.45 EADC 1.45 EADC 1.45c EASC 1.47 EASC 1.47 EASC 1.47 EASC 1.47

Polymer- ization (time,

hr)

68 68

165 192 89

189 94

Copolymer CrN

Yield (%)

2.56 5.51 1.85 -0

0.40 1.50 1.02

content [vld (%) (dl/g)

41.4 0.09 47.3 0.07 5.6 . . .

. . . . . . 45.3 0.20 46.6 0.10

a cisltrans = 81.8h8.2. " 1 mole % AIBN was added to aluminum compounds. Without AIBN. DMF, 3 O O C .

in the presence of EADC or ethylaluminum sesquichloride (EASC). No co- polymerization of BF and CrN occurs in the presence of a radical initiator, but BF copolymerizes with CrN in the presence of a small amount of AIBN as catalyst when the latter is complexed with an aluminum compound. Without AIBN the copolymerization proceeds slowly and the composition of the products deviates from the 1:l ratio. The copolymerizations are generally very slow, compared with the BF-AN or -MAN system? in spite of the notable polarity of the car- bon-carbon double bond of CrN. EADC is more effective than EASC for this copolymerization.

The effect of the molar ratio of BF, CrN, and EADC was investigated. As shown in Table 111, the use of a nearly equimolar amount of EADC against CrN induced the cationic homopolymerization of BF. In the presence of a small amount of EADC (EADC < CrN) and BF (BF < CrN) the CrN content of the products increases to almost 50% as CrN in the feed increases. Moreover, in the presence of a constant amount of EADC (EADC < CrN) the CrN content is also gradually increased to approximately 50% by increasing the total monomer concentration under the constant ratio of BF and CrN. Consequently these results suggest that this copolymerization is essentially alternating, and the high

TABLE 111 The Copolymerization of BF and CrN in the Presence of EADC in Toluene a t 30°C

EADC/ Polym- Cop o 1 y m e r BF CrN" CrN" erization CrN

(mole/ (mole/ (feed (molar (time, Yield content [vIc liter) liter) mole %) ratio) hr) (%) (%) (dl/g)

1.85 1.54 45.4 0.95 164 7.9 43.9 0.08 1.85 2.25 54.9 0.65 164 4.7 47.8 0.09 1.85 4.60 71.3 0.32 164 0.3 49.4 ... 2.47 2.05 45.4 0.71 163 4.4 45.4 0.10 3.08 2.57 45.6 0.57 163 4.0 47.6 0.10 3.70 3.07 45.3 0.47 163 2.7 47.8 . . .

a cisltrans = 69.9/30.1. EADC 1.46 mole/liter and 1 mole % AIBN were used in EADC. DMF, 3 O O C .

BENZOFURAN WITH CROTONONITRILE 2959

BF content (> 50%) sometimes observed is attributed to the homopolymerization of BF that occurs as a side reaction. In addition, this alternating copolymer is most easily obtained when EADC/CrN = 0.5-0.7 and BF/CrN = 0.4-0.6 in the feed molar ratio.

Next, the influence of the cis or trans isomer of CrN on this alternating co- polymerization was studied. The cis/trans ratio of CrN was controlled by mixing pure fractionated cis- and trans-CrN. The low ratio of EASC/CrN or EADC/ CrN was adopted to exclude the influence of cationic side reaction. According to gas chromatography, the cis-trans isomerization of CrN during the copoly- merization was not observed. The results are summarized in Table IV.

It was found that cis-CrN is more reactive than the trans isomer in the presence of both EADC and EASC. This notable difference is interesting in relation to the mechanism of the alternating copolymerization and the character of the bi- nary and ternary complexes involved.8

Copolymerization of BF and ClAN

According to Otsu et al.,7 ClAN's good radical polymerizability is due to its large e value and is expected to be an excellent electron-accepting monomer. Tables V and VI show the result of the copolymerization of BF and ClAN.

Generally, this copolymerization proceeds rapidly, but the composition of the products is unexpectedly dependent on experimental conditions. Features of the BF-C1AN copolymerization under the influence of strong Lewis acids such as EADC and EASC are that almost all products are rich in BF and the effect of AIBN is negligibly small, although the rate of copolymerization of BF and complexed AN is markedly accelerated by AIBN.2 In the presence of a constant amount of EASC and a constant feed monomer ratio the ClAN content decreases as the amount of ClAN feed increases (Table V). On the contrary, the AN content increases in the BF-AN system2 or the CrN content is increased to almost 50% in the BF-CrN system by increasing the AN or CrN feed. These facts suggest that the cationic polymerization of BF may be induced by some cationic species produced by the interaction between ClAN and Lewis acid. Conse- quently the real copolymerizability of ClAN must be evaluated after removal of as much of the cationic side reaction as possible by using a weak acid cata- lyst.

In fact, the equimolar copolymer of BF and ClAN is obtained easily by the alkoxyaluminum compounds (Table VI), which is considered an alternating copolymer because no BF-BF dyad is contained in these copolymers, as indicated in an earlier article. The addition of AIBN accelerates the BF-C1AN copoly- merization by these weak acid catalysts, and as a result the relative rate of the alternating copolymerization with BF is

ClAN > AN2 > MAN2 This order agrees with the order of the e value.

'H-NMR Spectra of the BF-CrN and the BF-ClAN Copolymers

Figure 1 describes the 220 MHz 'H-NMR spectra of the BF-CrN alternating copolymer measured in ~G-DMSO at 120°C. By comparison with the lH-NMR spectra of the BF-AN copolymer,2 each signal is assigned as follows; at 64.6-34

TA

BL

E I

V

The

Cop

olym

eriz

atio

n of

BF

and cis- o

r tra

ns-C

rN in

Tol

uene

at 3

OoC

CrN

C

atal

ysta

Po

lym

- C

opol

ymer

B

F (m

ole1

(m

ole1

(f

eed

(cis

ltran

s (m

ole1

er

izat

ion

Yie

ld

CrN

con

tent

Id

b lit

er)

liter

) m

ole %

) ra

tio)

liter

) (t

ime,

hr)

(%I

(%)

(dllg

)

2.47

2.05

45

.4

100/

0 EA

SC

1.47

14

2 4.

1 46

.4

0.10

2.4

7 2.

05

45.4

85

.611

4.4

EASC

1.

47

142

3.2

41.3

0.

10

2.47

2.05

45

.4

52.7

147.

3 EA

SC

1.47

14

2 1.

6 43

.3

...

2.47

2.05

45

.4

35.0

165.

0 EA

SC

1.47

14

2 1.

1 41

.3

0.21

2.4

7 2.

25

47.1

lO

O/O

EASC

1.

47

186

5.5

48.4

0.

10

2.47

2.25

47

.7

74.4

125.

6 EA

SC

1.47

18

6 3.

1 48

.5

0.07

2.4

7 2.

25

41.1

40

.415

9.6

EASC

1.

47

186

1.3

48.1

0.

07

2.47

2.25

47

.7

26.5

173.

5 EA

SC

1.47

18

6 1 .o

48.2

..

. 2.

47

2.25

41

.7

0.81

99.2

EA

SC

1.47

18

6 0.

5 ..

. ..

. 1.

41

2.29

61

.9

1001

0 EA

DC

1.4

8 96

5.

1 48

.1

0.08

1.

41

2.29

61

.9

74.4

125.

6 EA

DC

1.4

8 96

3.

1 50

.3

0.07

1.

41

2.29

61

.9

54.0

146.

0 EA

DC

1.4

8 96

2.4

48

.5

0.12

1.

41

2.29

61

.9

26.0

174.

0 EA

DC

1.4

8 96

1.

0 46

.6

...

1.41

2.

29

61.9

0.

8199

.2

EAD

C 1

.48

96

0.3

...

...

a 1

mol

e % A

IBN

was

add

ed to

EA

DC

or E

ASC

. D

MF,

3OOC

.

BENZOFURAN WITH CROTONONITRILE 2961

I n

TABLE V The Copolymerization of BF and ClAN in the Presence of EASC" in Toluene a t 3OoC

Polym- ClAN erization Cop o 1 y m e r BF

(mole/ (mole/ (feed (time, Yield ClAN content hIc liter) liter) mole %) hr) (%) (%) (dl/g)

0.39 1.47 79.3 15 21.7 51.3 0.06 0.77 1.47 65.7 15 50.2 49.0 0.07 1.54 1.47 48.9 2 13.8 43.8 0.18 3.08 1.47 32.3 2 14.2 38.2 0.30 2.22 2.22 50.0 2 20.1 43.4 0.13 2.95 2.95 50.0 1.5 19.7 39.2 0.15 3.63 3.63 50.0 1.5 26.2 38.4 0.17 1.54 8.08 84.0 2 12.3 35.5 0.11 1.54 2.93 65.6 2 14.7 41.5 0.10 1.54 2.93 65.6 2 16.1b 40.3 0.09

a 1.47 molehter. b 1 mole % AIBN was added to EASC.

CHC13,3O"C.

I I I I I 1 1

8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0

d . PPm

Fig. 1. 220 MHz 'H-NMR spectrum of the alternating copolymer of BF-CrN in ds-DMSO at 120°C. Preparative conditions of the copolymer [CrN]/[BF] = 2, [CrN]/[EADC] = 2. AIBN: 1 mole % for EADC; polymerization temperature: 30°C; CrN content in copolymer: about 49 mole YO.

and 3.42 ppm, to the a- and P-methine of BF-unit, and at 62.82-3.09,2.32, and 1.11 ppm, to the a-methine, 0-methine, and methyl of CrN-unit, respectively. The signals observed between 66.66 and 7.05 ppm are ascribed to four protons on the benzene ring.

DMSO is one of the most powerful solvents for these copolymers but unfor- tunately induces the decomposition of the BF-C1AN copolymer. Therefore its 'H-NMR spectra were determined in d6-DMSO at low temperature (60°C) or in deuterochloroform at 80°C, although the division of spectra is not so clear. The spectrum pattern of this copolymer is simple and the a- and P-methine of the BF unit are observed at 65.18 and 4.08 ppm and the methylene peak, a t 2.73 ppm, respectively (in ~G-DMSO). When the composition ratio BFKlAN is larger than 1:1, the additional two peaks are observed at 64.18 and 2.98 ppm because of the a- and P-methine of the homopolymer of BF.

TAB

LE V

I T

he C

opol

ymer

izat

ion

of B

F an

d C

lAN

in th

e Pr

esen

ce o

f Alu

min

um C

ompo

unds

in T

olue

ne a

t 30°

C

BF

ClA

N

Cat

alys

t Po

lyrn

- C

opol

ymer

(mol

e/

(mol

e/

(fee

d (m

ole/

er

izat

ion

Yie

ld

ClA

N c

onte

nt

[?Ib

(%)

(dl/g

) lit

er)

liter

) m

ole

%)

liter

) (t

ime,

hr)

0.77

1.

47

65.7

EA

DC

1.

46

2.5

12.4

22

.1

...

1.54

1.

47

48.9

EA

DC

1.

46

2.5

21.1

17

.5

...

3.08

1.

47

32.3

EA

DC

1.

46

2.5

33.7

14

.4

...

0.77

1.

47

65.7

(E

tO)E

to.5

A1C

1i.s

1.47

17

19

.3

51.5

0.

13

1.54

1.

47

48.9

(E

tO)E

b.5A

lCli.

5 1.

47

6.5

9.4

43.9

0.

23

3.08

1.

47

32.3

(E

tO)E

to~A

1Cli

s 1.

47

4.5

10.4

37

.1

0.37

0.

77

1.47

65

.7

(EtO

)Eto

.sAIC

li.sa

1.

47

17

33.0

51

.7

0.13

0.

77

1.47

65

.7

(Et0

)EtA

lCl

1.46

70

2.

1 63

.0

...

1.54

1.

47

48.9

(E

t0)E

tAlC

l 1.

46

46

2.8

59.7

..

. 3.

08

1.47

32

.3

(Et0

)EtA

lCl

1.46

46

8.

5 52

.9

0.07

1.

54

1.47

48

.9

(Et0

)EtA

lCl"

1.

46

29

6.5

54.0

0.

06

3.08

1.

47

32.3

(E

tO)E

tAIC

la

1.46

23

20

.9

49.5

..

. a

AIB

N w

as a

dded

1 m

ole %

for a

lum

inum

com

poun

ds.

' CHC1

3,3O

0C.

c 8 "S T

BENZOFURAN WITH CROTONONITRILE 2963

Discussion

In this work the alternating copolymers of BF and CrN or ClAN were newly synthesized. The rate of copolymerization of BF with five nitrile monomers is the following:

ClAN > AN2 > MAN2 > cis-CrN > trans-CrN Furukawa et al? have reported that the optimum Lewis acidity exists and

that acid that is too strong is unfavorable to butadiene-AN alternating copoly- merization. On the other hand, the polarity of the double bond of complexed nitrile monomers increases as the acidity and acid strength of Lewis acid in- crease.6 The slow copolymerization of BF-CrN system may be due to excessive polarization of the CrN monomer. This possibility, however, is refuted by the fact that EADC is more effective for BF-CrN copolymerization than EASC and other weak acids.

The reactivity of cis-CrN is superior to that of trans-CrN, whereas the po- larizability of both monomers is of almost the same magnitude.

The apparent reactivity of monomer is thought to be a function of the elec- tronic state of olefinic double bond and the steric factor, to be due to substituents. Generally, the reactivity of the double bond of cis monomer, such as dimethyl maleate, is larger than that of trans isomer.'O Similar unstability may exist in cis-CrN. The molar refraction of cis- and trans-CrN is calculated at 20.52 and 20.68, respectively, from their n~ and density dzo.ll The small molar refraction of cis-CrN may agree with its high reactivity.

The Q, e value of monomer is a useful measure of its reactivity. We have no data, however, for the Q, e value of CrN. According to the Q, e values of acrylic acid and crotonic acid,1° we can expect that the @-methyl substituent will decrease the e value of acrylic acid by 0.3-0.4. Therefore the &methyl substituent of CrN may decrease its e value and subsequently its reactivity will decrease to the same level of MAN. Cis-CrN perhaps possesses a smaller e value than trans- CrN, a similarity of such systems as maleate and fumarate, 1,2-dichloroethylene, or stilbene.lo This does not coincide with the higher reactivity of cis- CrN.

On the other hand, in this kind of copolymerization, as well as in conventional radical polymerization, the steric hindrance of the substituent in the monomers may be influential factors. It has been reported that in the transition state for the radical polymerization of a,p-disubstituted monomer the steric interference is more serious than in the final product.1° The inferior reactivity of CrN may be caused by steric hindrance. Because of its low reactivity, tram-CrN may have a more sterically hindered transition state than cis- CrN. However, a detailed discussion of the transition state of copolymerization is not feasible because its opening mode is not yet clear.

Earlier we treated this kind of alternating copolymerization as a polymerization of the ternary complex of Lewis acid, acrylic monomer, and olefinic donor monomer.2 According to this mechanism, the polymerizability of the ternary complex of cis-CrN may be larger than that of trans-CrN. This is also an im- portant influential factor in the high reactivity of cis-CrN, but it has not been resolved experimentally.

According to Gaylord et d.,4 the alternating copolymerizability of ClAN with styrene is inferior to AN and even to MAN perhaps because of the steric hin- drance of the a-substituent. In this work, however, ClAN is considered to be the most alternatingly copolymerizable with BF, a fact that is compatible with

2964 FURUKAWA, KOBAYASHI, AND NAGATA

the e value. It is important in any detailed investigation of this system to reduce the cationic side reaction.

References

1. G. Kramer and A. Spilker, Ber. Dtsch. Chem. Ces., 23,78,3279 (1890); A. Mizote, T . Tanaka, T. Higashimura, and S. Okamura, J . Polym. Sci. Part A-1, 4,869 (1966).

2.-J. Furukawa, E. Kobayashi, and S. Nagata, J. Polym. Sci. Polym. Chem. Ed., 16, 2945 (1978).

3. Y. Kobuke, J. Furukawa, and T. Fueno, J. Polym. Sci. Part A-1, 5,2701 (1967). 4. N. G. Gaylord and B. K. Patnaik, Makromol. Chem., 146,125 (1971). 5. R. C. Fuson, T. W. Kneisley, and E. W. Kaiser, Org. Synth., 24,33 (1944). 6. J. Furukawa, E. Kobayashi, and S. Nagata, J. Polym. Sci. Polym. Chem. Ed., 12, 1799

7. B. Yamada and T. Otsu, J . Macromol. Sci. Chem., A3,1551 (1969). 8. J. Furukawa, E. Kobayashi, and S. Nagata, J. Polym. Sci., to appear. 9. J. Furukawa, E. Kobayashi, K. Haga, and Y. Iseda, Polym. J., 2,475 (1971).

(1974).

10. G. E. Ham, High Polymers XVZII, Copolymerization, Wiley-Interscience, New York,

11. E. L. Eliel, Stereochemistry of Carbon Compounds, McGraw-Hill, New York, 1962, p. 326. 1964.

Received July 12,1977