Azole analogues of polypyromellitimides

V. P. Y~.VSTAF'~V eta/.

2884

9. H. lt~.ERWEIN, E. BATTENBURD, H. GOLD, E. PFEIL and G. W~.LFANG, Prakt. Chem. 154: 83, 1939 10. G. T. MERRALL~ G. LATREMOILLE and A. M. EASTHAM, Canad. J. Chem. 38: 1960, 1967 11. M. BERSTOL and F. TRELOAR, in [8], p. 11 12. CHEMICAL HANDBOOK, Vol. I, p. 937, Goskhimizdat, 1962 13. L. M. BATUNER and M. Ye. POZIN, Matematicheskie metody v khimicheskoi tekhnike (Mathematical Methods in Chemical Engineering). 104, 1963

AZOLE ANALOGUES OF POLYPYROMET,T,ITIM~ES* V. P. YEVSTAF'EV, G. I. BRAZ, A. YA. YAKUBOVICH (dec.) and G. F. SKALYGI~ L. Ya. Karpov Physicoehemical Research Institute

(Received 27 May 1970) THv. completely aromatic polyheterocycles known at present include only a small number of polymers from which stable materials capable of withstanding considerable stretching strains over a wide temperature range are obtainable. One of the foremost of these polymers is the well-known poly[N,N'-(p,p'-phenoxyphenylene)pyromellitimide] CO CO

/ '

\-'/

~

I

W _1.

\co/N//\co/

I n attempting to discover the particular structural peculiarities of polymer I that underlie its favourable properties we decided to investigate the extent to which the presence of the pyromeUitimide ring is an indispensible factor in the structure of this polymer, and the extent to which partial or complete substitution of the ring in question b y triple-ring heterocycles of Similar structure (i.e. benzo-bis-imidazole and benzo-bis-oxazole heterocycles, containing no carbonyl groups) would influence the strength and deformation properties of polymer I. We therefore synthesized polymers I I - V , and also polymer VI, which is the benzo-bisoxazole analogue of poly-[N,N'-(p-phenylene)pyromellitimide] (VII) X

X

/ Y Y \o-lII--VI t

* Vysokomol. soyed. A18: 1~o. 11, 2565-2571, 1971.

Azole analogues of polypyromellitimides

2885

For polymer II--X=NH, R=p,p'-C6H4OC~H,, III--X=0, R=p,p'-C6H40C6H,, IV--X----NH, /

CO CO \.,,~/ \

R=p,p"C6HaOCeH4 - N

H

]

N--CeH,OCeH~--P,P" ,

\co/~co /

CO

/

~/%/~

V--X----O, R=p,p'-CeH,OC,H,--N

I~

CO

N--C,H,OC6H,--p, p' and

\co--co CO V I - - X = 0, R----p-CeH,--N/

\

]

/ CO

~

~N--C,H~--p

\co/\//\co/ The completelyimidazolicand completelyoxazolic analogues of polymer I, i.e. poly-[2,6-(p,p'-phenoxyphenylene)benzo-(1,2-d: 4,5-d')-bis-imidazole] (II) and poly-[2,6-(p,p'-phenoxyphenylene)benzo-(1,2-d : 5,4-d')-bis-(oxazole)] (III) were prepared by polycondensation of 1,2,4,5-tetraaminobenzene tetrachlorohydrate and 4,6-diaminoresorcinol dichlorohydrate (respectively) with 4,4'-dicaxbo, methoxydiphenyloxide and polyphosphoric acid (PPA). The use of PPA, thoroughly purified, as well as variations in the ratio of the starting materials and careful finn

// 7

"~1o

/

//i

I

i

I

IZO

180

220

T,oo

Change in ~u~ of polymers H (6, 7-9) arid I I I (10, I I ) (0.2 g/dl, cone. IT=SO,, 25°}

vs. polyeondensation temperature. Rate of temperature rise lO°/hr. Figures at the curves are the numbers of the experiments (see Table 1).

2886

V . P. Y E V S T ~ ' E V e$ a/.

observation of t h e changes in viscosity during the polycendensation process, enabled us to determine the reaction conditions whereby I I and I I I are obtained with unusually high viscosity values for polycendensation polymers (see Table 1). On observing the changes in Tun while the temperature of the reaction mixture was rising (see Figure) it was found t h a t the molecular weight of I I and I I I is highest at 180 °. During the synthesis of I I with an excess of tetraaminobenzene a further rise in temperature to 200 ° has practically no effect on ~lin (see Figure, ~urves 7, 8). With an equimolar ratio of the starting materials there is some reduction in viscosity at 220 ° (curve 5), and further heating to 240 ° results in the loss of complete solubility of I I in sulphuric acid. With a 1 . 5 ~ excess o f dicarbomethoxydiphenyloxide at the maximum reaction temperature (180 °, curve 9) the value of t/n, is close to ~/~ of I I prepared with an equlmolar ratio o f the starting materials, bu~ on further raising the temperature to 200 ° the viscosity is greatly reduced. The fact t h a t the highest molecular weight of I I is obtained with quite a small excess (0"8~/o) of tmtraamJnobenzene cannot be due to branching of the polymer, ~ince on further increasing the amount of tetraaminobenzene to 2 ~ a polymer with considerably lower viscosity is obtained (curve 8). The great importance ~)f using only small excess of tetraaminobenzene is apparently due to the fact t h a t it m a y contain traces of solvent because the instability of the tetrachloroh y d r a t e in a vacuum at high temperature necessitates drying under very mild ,conditions. The end groups of I I prepared with a 2~/o excess of tetraaminobenzene remain active even when the reaction mixture is heated to 200 °, since the addition o f dicarbomethoxydiphenyloxide (up to an equimolar ratio) to a reaction solution ~ f this polymer increases the viscosity of the latter. On the other hand, the end groups of polymer I I when prepared with an excess of 4,4'-dicarbomethoxydiphenyloxide at the maximum reaction temperature of 200 ° are inactive. The viscosity of this polymer is not increased either on adding tetraaminobenzene a t 80 °, or by repeated heating to 180 °. I n the synthesis of I I I heating above 180 ° reduces ~/ltn with an equimolar ratio of dicarbomethoxydiphenyloxide and diaminoresorcino] (curve 10) or with a 1 ~ excess of the latter. Polymers TI and I I I are soluble in polyphosphoric acid (PPA) and in con~entrated H~S04 and have fibre-like properties. Fibre with a tensile strength ~)f 11-15 g/rex and a breaking elongation of 21-31~/o was obtained in preliminary experiments by Andrichenok (of the Moscow Textile Institute) from a 1~o ~olution of I I in P P A (~au----2.7) using a water precipitation bath (50°). After it had been stretched on a hot metal surface at 600-800 ° the fibre strength increase d to 30-40 g/rex, and the breaking elongation reached 9"7~/o. The special features o f a solution of I I in P P A (high viscosity at a low concentration) are conducive

2887

Azole analogues of p o l y p y r o m e l l i t i m i d e s TABLE 1. CONDITIONS FOR "J:~.: pREPATtATION OF POLYMERS I I AND I ~ ( R a t e o f t e m p e r a t u r e rise, 10°/hr, m a x i m u m r e a c t i o n t e m p e r a t u r e - - 2 0 0 e)

Exp. No.

1 2 3 4 5 6

7 8 9

10 11

Starting material*

Polymer

II

TBT TBT TBT TBT TBT TBT TBT TBT TBT DRD DRD

: : : : : : : : :

CO CIV[ CM CI~ CI~I CM CM C~I CM : GM : CM

Ratio, mole

T o t a l conConcen centration tration of starting Time of o f reac- h e a t i n g materials, tion mmole/ at T m i x solution /100 g, % PPA

1:1 1:1 1:1 1:1 1:1 1.008 : 1 1.008 : 1 1.02 : 1 1 : 1.015 1:1 1.01 : 1

7.5 6-8 6.5 5.9 15 15 15 16 15 11 11

1.25 1.13 1.08 0"99 2-5 2.5 2.5 2.0 2.5 1.8 1-8

• * TBT--Tetraaminobenzene tetrachlorohydrate; CO---4,4'-dicarboxydi1~henyloxide; diphenyloxide; DB, D---dlaminoresorcinol dichlorohydrate. :~ Maximum reaction temperatare 190 °. ~f Maximum reaction temperature 220 °. ~Vot¢. ~lln was measured at a concentration of 0.2 g : dl HzSO4, 25 °.

5

0.7

6

~4.0

3t

3.0 2-7 (2.7) 3.0 8.7 6.7 (9.7) 2.6 1.8 8.0(10.1) 4.1

3 6 1 1

1 1 It

CM-=4,4'-decarbomethoxy-

TABT.~ 2. CONDITIONS FOR TJi~ POLYCONDENSATIOlq OF DTAMT~ESV I I I - X "W,'A'~PYROMELLITIC I)IA_NITY'DRIDE, 20 °

Diamine

VIII IX

X

S o l v e n t for t h e polycondensation

Dimethylsulphoxide Hexamethylphosphorotr~mjde Dimethylacet~mide Dimethylacet~mide Dimethylsulphoxide

Time of the addition of pyromellitic dianhydride, min

st~ing

Excess of pyromellitic dianhydride,

~lln*

materials, mole/1.

%

2or

0"20

0.1

2.35 (dimethylsulphoxide)

10

0.24

0.0

3O-40

0"16-0.26

0.2-0"8

2O

0-25

0"5

15

0"25

0.7

1.8 ( d i m e t h y l f o r m amide) 1.8-2.5 ( d i m e t h y l formamide) 1.33 ( d i m c t h y l sulphoxide) 1-1.4 ( d l m e t h y l su]phoxide)

* 0.5 g of polymer in 100 ml of solution, 25 °.

t Reaction temperature, 25%

T o t a l concentration of the

2888

V.P. Y~.VSTAF'~.Vet OJ.

[2,6-di(p,p'-phenoxyphenylene)benzo-) (1,2-d : 4,5-d')-bis-imidazolo] pyromellitimide (IV) and poly-N,N'-[2,6-di-(p,p'-phenoxyphenylene)benzo-(1,2-d : 5,4~')bis-oxazolo]pyromellitimide (V) and also the imidazolic analogue of VII, polyN,N-[2,6-di-(p-phenylene) benzo(1,2-d : 5,4-d')-bis-oxazolo]pyromellithnide (VI) only 50~/o of the pyromellitimide units of the corresponding pyromellitimides are replaced by azole rings. 2, 6 -di- (p,p '-am iuophenoxyphenyl )benzo -( 1,2 -d : 5,4 -d') bis-imidazole (VIII) was synthesized by condensation of tetraaminobenzene tetrachlorohydrate with p,p'-aminophenoxybenzoic acid in PPA. The interaction of V I I I with pyromellitic dianhydride in dimethylsulphoxide resulted in polycarboxyamide which in the form of films cast from the reaction solution was converted to IV by thermal cyclodehydration. Polymers V and VI (see Table 2) HX XH X X / \ C-R-NH2 ~nhyd~a~ HOOC--R--NH2 ÷N-HI- R - C PPA

H~lV

NH,

~

/~

N | ooo

N X

X

N

N

/

were synthesized in the same way as IV, using the substances already described in [1], namely 2,6-di-(p,p'-aminophenoxyphenyl)benzo-(1,2-d:5,4-d')-bis-oxazole (IX) and 2,6-di(p-amiuophenyl)benzo-(1,2-d:5,4-d')-bis-oxazole (X), where for V I I I - - X = N H , R----p,p'-C6H,OCeH4; I X - - X = 0 , R=p,p'-C6H~OC6H~ and X X - - 0, R :-I~-CeH4. To convert the corresponding polycarboxyamides to polymers V and VI we used both thermal and chemical cyclodehydration with a mixture of pyridine and acetic anhydride. The polymers prepared by either method have identical IR spectra. The structures of V and VI are confirmed by a comparison of their I R spectra with those of the previously synthesized [1] compounds modelling these polymers. The strength and deformation properties of the films of polymer V (Table 3) are close to those of polypyromellitimide I (~= 1700--2000 kg/cm ~, 8 : 7 0 - 2 0 0 ~ [2-4]) (Table 3). The breaking elongations of VI differ very little from those (5.5~) of the structurally-similar polypyromellitimide VII which was described in [5]. It was also pointed out in [51 that the tensile strength of VII--~-~990 kg/cm ~. It therefore appears that no major change occurs in the properties of the polymers when at least 50~/o of the pyromellitimide rings in the chain of polypyromellitimides I and VII are replaced by benzo-bis-oxazole rings. In contrast to the hnidoxazolic,polymer V the imide imidazollc polymer IV has small breaking elongations, and it also differs from the other polymers of similar structure by reason of its insolubility even in fuming nitric acid, and in

Azole analogues of polypyromeUitimidos

2889

T A B L E 3. P R O P E R T I E S OF FILMS (10-30 /l) oF IMIDAZOLIC ANALOGUES Olr POLYPYROMELLITIMIDES A T 20 ° ~lin Po-

ymers

IV V VI

Method of eyclizatdon

Thernml

for the original polyamido acid

T,=ax of thermally t r e a t e d film at 0.01-0.1 ram, i °C 350 350 200 400 400

2.35 2-5 1.98

Chemical Thermal Chemical

1-4 1.0

0"20"

0"2O"

kg/cm 2

%

1500 2000 1300 1700 1600

11 50 140 6.4 3"5

c o n c e n t r a t e d s u l p h u r i c a c i d . P o l y m e r I I is p a r t i a l l y s o l u b l e i n 9 8 % f o r m i c a c i d . T h e s o l u b i l i t y o f t h e p o l y m e r s a t ~ 20 ° i n c o n c e n t r a t e d H ~ S 0 4 a n d i n f u m i n g H N 0 s * is a s f o l l o w s : Polymer H2SO, HNOs

I p.s s

II s s

III s s

IV ins ins

V s s

V/ ins p.s

The thermogravimetric analysis shows that the temperatures of the onset of thermal decomposition of polymers I and II-VI are similar. The elementary analysis of the product compounds was carried out under the direction of K. A. Samurskaya. We wish to thank A. P. Simonov for discussing the IR spectra.

EXPERIMENTAL

Polyphosphor~c acid, n~ 1.4700, content of P20~ based on the refractive index [6] 82"3~o N,N'-dimethylacetamide, he~amethylphosphorotriamide and dimethyl~u2pho:~idc were distilled over Call2 before the polycondensation, b.p. 85°/35 mm, 97°/7 m m and 83°/15 ram, respectively. 4,d'-Dicarbo:vydiph~nylozidc was prepared b y oxidation of 4,4'-ditolyl ether b y K M ~ O , in wat~r-pyridine solution. Yield, 209/o, m.p. 333 ° (from CHsCOOl=I; revised, decomposes). 4,4"-Dicarboxydiphenyloxide [7] m.p. 154.5-155 ° (from CeHe)4,6-Diaminore, orcinol dichlorohydrate was prepared in the manner described in [1]. 1,2,4,5-Te~raaminobenzcne tetrachtorohydrate was synthesized from N,N'-ditosyl-mphenylenediamine (XI) [8] with m.p. 174-174-5 ° (from methanol) in the manner described in [9], except t h a t the combination of p-HO,SCsH,N,C1 with X I , as we founds must be carried out at p H = 9 - 5 - 1 0 , a n d not at p H =7-7.5, as in [9]. The t e t r a c h l o r o h y d r a t e was double repreeipitated with concentrated I-IC1 from a solution of the l a t t e r in 6Yo HC1, a n d * s =soluble; p.s = p a r t i a l l y soluble; ins =insoluble. Prior to the solubility determination polymers I a n d I V - V I were heated for 1 h r at 350°; polymers I I a n d I I I did not undergo heat t r e a t m e n t after the synthesis. The solubility was determined after the sample h a d been stirred for 3 hr in the solvent under investigation.

2890

V. P. YEVSTAF'EV eta/.

was t h e n washed with methanol s a t u r a t e d with HCI, and dried for 2 hr over PzO6 a t 40°/2 ram. I t is advisable to convert the ditosy] derivative o f tetraaminobenzene to tetrachIorohydrate o n l y a few days prior to use, as the l a t t e r darkens during prolonged storage, even in evacuated ampoules. Yield of tetraehlorohydrate 25 7o. 2,6.Di-(p,p'-aminophenoxyphenyl)benzo-(1,2-d : 4,5.d').bis.imidazole ( F I I I ) . 7.1 g (0-025 mole) of tetraminobenzene tetraehlorohydrate was gradually a d d e d a t 80-85 °, with stirring, to 120 g of P P A t h a t h a d first been heated a t 200 ° in a current of argon, then 11.5 g (0.05 mole) of p-(p'-aminophenoxy) benzoic acid was added, and the temperature was raised a t the r a t e o f 10°/hr to 170 °, a n d the mixture was stirred for a further 3 hr a t this temperature. The reaction m i x t u r e was then decanted into water containing ice, a n d the resulting precipitate was e x t r a c t e d with water u~til a neutral reaction was obtained, and was then transferred to 1 1. o f a 5 ~ solution of (NHa)gCO,, where it was k e p t for 20 hr, after which it was suction-filtered a n d e x t r a c t e d until the reaction of the filtrate to :NH+ (Nessler's reagent) became negative. Yield 757o, m.p. 423 ° (from pyridine-Fwater; revised).* F o u n d , 7o: Calculated,

C 73.29; C 73.28;

H 4.76; H 4.61;

:N 16.11. N 16.03.

Cs,H24N,OI.

D i a m i n e V I I I is fairly soluble in dlmethylsulphoxide and amide solvents, b u t v e r y sparingly soluble in methanol.

Poly-[2,6-(p,lo'-pheno~yphenyle~e)benzo-(1,2-d : 4,5-d')-bis-imidazole](11).To 40 g of P P A preheated for 4 hr in a current of argon, with stirring, at 200 ° were added (at 80-85 °) 3.02 mmo]es of tetraaminobenzene tetrachlorehydrate; w h e n the evo]ution of HCI ceased 3.00 mmoles of 4,4'-dicarbomethoxydiphenoloxide were added, and the mixture.was stirred, raising the temperature to 200 ° at the rate of 10°/hr. The mixture was then cooled to ~ 2 0 % diluted with suIphuric acid to a concentration of 0.5 g of polymer in 100 ml, after which it was decanted in a thin stream into ~ 2 I. of water containing ice. The resulting fibrous precipitate was extracted with water to obtain a neutral reaction, then transferred for ~ 20 hr to a 5 ~o (NH~)~CO8 solution, then extracted to obtain a negative reaction to :NH + in the filtrate; the precipitate was then dried, precipitated (once) from suIphuric acid, after which it once again underwent the above treatment, and was v a c u u m dried at 200 °. Yield ~ 1007o. Found,' 7o:

C 71-92;

l:I 4.21;

N 14-21,

Calculated, 7o:

C 74.08;

H 3.73;

:N 17.21.

incombustible residue 1"57o. Cz0I-II~N~O.

.According to the results of emissive analysis the residue contains A1, Si, and traces of Mg a n d Cu. The I R spectrum of polymer I I corresponds to the spectrum of dJ~mine V I I I . Table 1 gives the ratio of the starting materials a n d the time of heating a t the m a x i m u m t e m p e r a t u r e in the other experiments. During the po]ycondensation the viscosity of samples o f t h e reaction solution was determined, i.e. the viscosity of samples diluted with concentrat e d HsSO4 to a concentration of 0.2 g of p o l y m e r in 100 ml of solution a t 25 °. The viscosity was found b y calculating the H s S O J P P A ratio for the resulting polymer solution, a n d the quotient was determined b y dividing the flow time of the polymer solution b y the flow time o f the same mixture of H~SO~ a n d P P A . Poly-[2,6-(.~,p'-phenoxyThenylene)benzo-(1,2-d : 5,4-d'-bis-oxazoteJ ( I I I ) was synthesized in t h e same w a y as polymer I I , a p a r t from the repreeipitation from HsSO4. * The melting point of this substance was determined b y p u t t i n g the capillaries in a preheated copper unit, as described in [1].

Azole analogues of polypyromollithnides Found, ~/o: C 70.86; Calculated, ~o: C 73-62;

H 4.17; H 3.09;

N 6.81. 1~ 8.59.

2891

CaoH10N2Os.

Polymers I V - V I were prepared in two stages. I n the first stage pyromellitic dianhydride was added in the course of 10-40 rain a t 20-25 °, with stirring, to a suspension of the appropriate diamine in the solvent shown in Table 2, and stirring was continued for a further hour. The solutions obtained in this way were kept at 5 ° . After several days these solutions generally t u r n cloudy, b u t after heating for a shor~ time to 40-60 ° they again become trans. lucent, a n d m a y be used for the preparation of films. W h e n it has t u r n e d cloudy a solution ofpolycarboxyamide from diamine X in dimethylacetamide does n o t become homogeneous even at 80 ° . To obtain the films the polycarboxyamide solutions were coated on glass and dried at 40--50 ° in a current of nitrogen, after which they underwent cyclization followed by further heat treatment.

Poly-N,2C'-[2,6-di-(p, p'-pherm:ajphenylene)benzo (1, 2-d : 4,5-d')-bis-imldazolo]-tryromellitirnide (I1 z) was prepared b y thermal cyclohydration of the polycarboxyamide film removed from the glass (30 rain at 180 °, a n d 1 hr at 350°). Found, ~/o: C 70.87; Calculated, ~o: C 71.39;

H 4.13; H 3.14;

N 13-05. :N 11-90.

C4,H2zl~606.

Poby-lg,~C'-[2,6.di-(19, t~-1~heno~yphenylene)benzo (1, 2-d : 5.4.d').bis-o~azolo]pyromellitimi. de (V). Bright yellow films of this polymer were obtained b o t h b y thermal a n d b y chemical cyclization of a film of the appropriate polyamido acid. The thermal cyclization was carried out with the polycarboxyamide film cast from dlmethylacetamide solution, the film being heated under the same conditions as were specified for IV, while fastened in a holder. l~ound, ~o: C 71.58; Calculated, ~o: C 71-19;

H 3"00; I-I 2.84;

N 7"41. :N 7.91.

C,2H2oN,Os.

The use of hexamethylphosphorotriamide as solvent in the polycondensation results in black films containing a n incombustible residue after the thermal cyelodehydration. The separation of the polycarboxyamide from hexamethylphosphorotriamide solution b y benzene, with subsequent dissolution in dimethylacetamide makes it possible to obtain films which, though black, are strong a n d contain no incombustible residue. The best results are obtained by conducting the polycondensation in dimethylacetamide. For the chemical cyclodehydration a polycarboxyamide film cast from dimethylacetamide solution was kept for 20 hr in a closed vessel containing a mixture of benzene, pyridine a n d acetic anhydride (2 : 2 : 1 b y vol.), after which it was kept in benzene for 1 hr, and in alcohol for 15 min, and was then vacuum-dried for 2 hr at 200 °. Pound, ~o:

C 70.73;

Poly-2C,2C'-[2,6.di.(p-phenylene)benzo(1,2-d

H 3-22;

1~ 9-08.

: 5,4-d')-bis-oxazo~o]pyromel~i$imide

( VI) was

prepared b y cyelization of a polycarboxyamide film cast from dimethylsulphoxido solution under the conditions specified for polymer IV. Found, ~ : C 68.78; Calculated, ~/o: C 68.71;

t t 2.81. ]~ 2.31.

Cso•12N406.

When heated to 350°/0.01-0.1 m m the film is brittle, and acquires the properties stated in Table 3 after further heating at 400°/0-1 m m for 20 rain.

2892

V. P. Y~.VSTAF'~.V et 0~.

For the chemical cyc]odehydration a layer of the polycarboxyamide solution in dimethylsulphoxide is coated on glass and immersed for 1 hr in a mixture (equal volumes) of pyridine and acetic anhydride, after which the film that has come offthe glass is transferred for 20 hr to a mixture of benzene : pyridine : acetic anhydride (8 : 1 : 1 by vo].). The film is then washed and dried, as in the case of polymer V, and then heated for a further 20 rain at 400°/0.1 mm. CONCLUSIONS (l) T h e a i m was t o d e t e r m i n e t h e e x t e n t to which t h e p r o p e r t i e s of p o l y [ N , N ' - ( p , p ' - p h e n o x y p h e n y l e n e ) p y r o m e U i t i m i d e ] (I) are d u e t o t h e special s t r u c t u r e o f t h e p y r o m e l l i t i m i d e ring. T o do so s t r u c t u r a l l y similar p o l y m e r s were s y n t h e s i z e d w h e r e t h e ring in q u e s t i o n was p a r t i a l l y or c o m p l e t e l y r e p l a c e d b y benzo-bis-imidazole or benzo-bis-oxazole heterocycles. (2) I t was f o u n d t h a t if h a l f t h e p y r o m e l l i t i m i d e rings in p o l y m e r I were r e p l a c e d b y b e n z o - b i s - o x a z o l e rings t h e s t r e n g t h a n d d e f o r m a t i o n p r o p e r t i e s o f t h e r e s u l t i n g p o l y m e r did n o t differ g r e a t l y f r o m t h o s e o f p o l y m e r I. (3) A s t u d y h a s b e e n m a d e o f s o m e f e a t u r e s o f t h e p r e p a r a t i o n of c o m p l e t e l y benzo-bis-imidazolic a n d c o m p l e t e l y bcnzo-bis-oxazolic a n a l o g u e s o f p o l y m e r I in p o l y s u l p h u r i c acid. Translated by R. J. A. EENDBY

REFERENCES 1. V. P. YEYSTAF'EV, G. L BRAZ and A. Ya. YAKUROVICH, Khlmiya heterotsikl. soyedinenii, 739, 1970 2. C. E. SROOG, A. L. ENDREY, A. V. ABRAMO, C. E. BERR, W. M. EDWARDS and K. L. OLIVIER, J. Polymer Sci. AS: 1373, 1965 3. M.M. KOTON, B. P. YAKOVLEV, A. P. RUDAKOV, T. S. KNYAZEVA, F. S. FLORINSKII, M. L BESSONOV, M. M. KULEYEVA, G. A. TOLPAREVA and L. A. LAIUS, Zh. prikl. khimii 38: 2728, 1965 4. M. L. WALLACH, J. Polymer Sci. 6: A-2, 953, 1968 5. U. S. Pat 3179633, 1965 6. R. G. DOWNING and D. E. PEARSON, J. Amer. Chem. Soc. 88:1718, 1961 7. V. IV[.IVANOVA, S. A. NEMLEVA, Z. N. SEINA, E. G. KAMINSKAYA, S. S. GITIS and A. Ya. KAMINSKII, Zh. organich, khimii 3: 146, 1967 8. I. V. ALEKSANDROV, Organicheskie poluprodukty i krasiteli (Organic Semi-products and Dyes). Goskhimizdat, No. 1, 196, 1959 9. J. ARIENT and J. MARHAN, Collect. Czechoslov. Chem. Communic. 25: 127, 1960