On the structure of diacetyl and p-phenylenediamine polycondensation products

340

M. N. SHIROKOVAand A. I. YAKUBCHIK

4. L. P. STEPOVIK, A. K. SHILOVA and A. Ye. SHILOV, Dokl. Akad. Nauk SSSR 148: 122, 1963 5. H. J. M. BARTELINK, H. BOS, W. VAN-RAAYEN and J. SMIDT, Congress Ampere, 13-16, Sept. 1961 6. H. BESTIAN, K. CLAUSS, H. JENSEN and E. PRINZ, Angew Chem. 74: 955, 1962 7. H. N. FRIEDLANDER and K. OITA, Industr. and Engng. Chem. 49: 1885, 1957 8. F. S. D'YACItKOVSKII, P. A. YAROVITSKII and V. F. BYSTROV, Vysokomol. soyed. 6: 659, 1964 9. F. S. D'YACHKOVSKII, Vysokomol. soyed. 7: 114, 1965

ON THE STRUCTURE OF DIACETYL AND p-PHENYLENEDIAMINE POLYCONDENSATION PRODUCTS*

M. N. SHIROKOVA and A. I. YAKUBOHIK A. N. Zhdanov State University, Leningrad

(Received 2/) March 1965)

TEE authors investigated the effect of ozone on polymers obtained by the polycondensation of benzil and p-phenylenediamine. F r o m the fact t h a t in products of ozonolysis benzil, benzoic acid and nitrogen-containing substances were obtained with satisfactory yields, it was concluded t h a t the C----N bond of the polymer is broken by ozone and its structure corresponds to a Schiff's polybase [21]. It is also known t h a t the C = N bonds of Schiff's bases [1, 2], hydrazones [3], N-oxides of certain heterocyclic compounds [4] are broken by ozone. In this study ozonizatior; was used to determine the structure of diacetyl and p-phenylenediamine (PDA) polycondensation products. The authors who prepared this polymer in benzene and glacial acetic acid [5,6] attribute to it the structure of a Schiff's poly-base:

o=F? n~4-5.

LCE. CH.

l_-O

o=o

I Ic~" A. CHs

(z)

A p o l y m e r of such s t r u c t u r e can be f o r m e d if t h e i n t e r a c t i o n b e t w e e n dia c e t y l a n d P I ) A t a k e s p l a c e b y r e a c t i o n b e t w e e n t h e c a r b o n y l g r o u p o£ d i a c e t y l a n d t h e amino-gTOUp of P D A a n d is n o t c o m p l i c a t e d b y s e c o n d a r y processes. W e s t u d i e d t h e c h e m i c a l s t r u c t u r e of t h e p o l y m e r o b t a i n e d b y d i a c e t y l a n d P D A p o l y c o n d e n s a t i o n in d i m e t h y l f o r m a m i d e t . * Vysokomol. soyed. 8: No. 2, 312-316, 1966. t Polyeondensation conditions were recommended by B. E. Davy4ov and Yu. A. Popov.

Structure of diacetyl and p-phenylenediamine

341

If we assume that, under the given conditions, a polymer of structure (I) is formed, b y the effect of ozone on this polymer products of polymer should be obtained b y breakdown at the C ~ N bond, namely: diacetyl, the product of its oxidation--acetic acid and prodttcts containing nitrogen. Polymer ozonization was carried out in different solvents (polar and nonpolar) and in every case a polymeric, nitrogen-containing substance was ob-

G

i

H

__

7388-71/00) ) I ~

\

j

V

1680-1700

lqlO0

800 1070 720JO I/¢00 1800 16GO P: cm -f

Fz(~. 1. IR spectra: a-- of a diacetyl and PDA polymer, b-- of the ozoT~izationproduct

in formic acid (soluble in methyl alcohol), c--of an ozonization product oxidized with hydrogen peroxide. rained as the sole product in amounts exceeding that of the polymer b y 14-16°/o . The product obtained, like the initial polymer, did not melt on heating, was soluble in formic acid, alkalies, partially soluble in methyl alcohol and insoluble in water. Elementary analytical data indicated a high oxygen content (30-40%). The carboxyl content was 27.40/0 . The I R spectrum of the ozonization products was identical with that of the initial polymer (Fig. 1), with the exception of

342

M.N. SmU~O~rOVAand A. I. YAKUBOHIK

the broad band with a maximtun at 3200 cm -~ (OH-group) and the considerably stronger band at 1680-1700 can-1 (CO-group) which also proves the presence of carboxyl groups in the ozonization product. During oxidation of the ozonization product with hydrogen peroxide, carbon dioxide and a water-soluble substance containing nitrogen were obtained. High-frequency titration showed an increase of up to 50.7% in the content of earboxyl groups. IR spectra confirmed the presence of earboxyl groups--there was a wide band with a maximum at 3220 cm -1 (OH-group) and a weak band at 1700 cm -1 (CO-group). In addition, there were bands which could be assigned to the absorption of NH-groups (3430 cm-1), C=--C-groups (1600 cm-~), C--N-groups (1102 cm-1), methyl or methylene groups (1400 cm -1) [7]. In the ozone-polymer reaction products and in products of oxidation with hydrogen peroxide of an ozonized polymer no substances were detected which would indicate the presence of a C-----N bond in the polymer. It can therefore be concluded that the structure of the diacetyl-PDA polycondensation produets does not correspond to the structure of the Schiff's poly-base (I) observed in ~he case o£ a polymer from benzil and PDA. The results obtained agree with well-known literature data which indicate the marked tendency of diacetyl to condensation and polymerization by the action of alkaline and acid substances [8-10]. The formation o£ a dimer, which is converted to p-xyloquinone in an alkaline medium, is particularly characteristic of diacetyl. Similar products may be formed under conditions of diaeetyl and PDA polycondensation. As was shown by Parini, Berlin, et al. [11], quinones condense with diamines to form poly-aminoquinones. In our case a product of the following structure may be formed: --CHs

0 (II)

_O~/~CH8 Unlike structure I, this structure is free from C~I~ bonds, it can therefore be recommended for the polymer investigated by the authors. In addition, the elementary composition of structure (II) agrees with experimental data to a greater extent than the elementary composition of structure (I) (Tables 1 and 2). IR spectroscopic data also agree with those o£ polyamino-quinones [12]. In the IR spectrum of polymers bands were observed which could be assigned to the absorption of the C----O group (1680 era-l), 1,4-disubstituted benzene nucleus (1614, 1506, 1170, 830 era-l), CHs-group (1386-1400 cm-1), lqH-group (3440-3380 em-~), but no absorption was observed at 1560-1580 cm -~ which, in similar compounds, corresponds to the C=N-group [13-15].

Structure of diaeetyl and p-phenylenediamine TABLE

I. E L E M E N T A R Y

Formula of the urdt

C O M P O S I T I O N OF A P O L Y M E R

343

OBTAINED FROM

Calculated, % Solvent in which [ O (by polycondensation C I I-I N differ- was carried out

DIACETYL AND

Found, % C

H

N

ertce)

I

j

I

CH~CH3

e.

>

\=~J

--N=

(I)

I

75"93 6"37:17"70 I i i [

f

o

O (by differ ence)

i =C-C=N--~

PDA

-

Benzene* Glacial acetic ! acid~

71.72 6.68 15.17

6.43

15.1i~ 72.721 6.68 14.871

5.66

72.81 6.49

/

\ N ,+--~ N 0 /\ =-//-~I-\-j~Ic~HH H-- 69'98 5"03! 11"66 13"33 amideDimethylf°rm"

I

69.451 6-86 69.401 6.73

1262 I 12.68/I

11.13

I

(II)

I {

* The d a t a were t a k e n from reference [5]. ? D a t a were t a k e n from reference [6].

TABLE

2. E L E M E N T A R Y

Objects of investigation

C O S I P O S I T I O N OF T H E O Z O N I Z A T I O N P R O D U C T OF A P O L Y M E R

Solvent ir~ which ozonization was carried out

Found, % Ratio to solvents C

H

N

O (by differOnCe)

Ozonizatiort product of the polymer

Formic acid

Ethyl acetate

Insoluble in methyl alcohol Soluble in methyl alcohol Insoluble in ethyl acetate

Soluble in ethyl acetate Ozonization product oxidized with hydrogen peroxide

51.001 50.931 42.25 41.99 43.16 43.30 44.54 44.19

5.10 5.21 5.45 5-22 4-58 4.91 4.73 4.61

10.57~ 10.48] 12'841

33.36

10"161 10.211

41-83

13.08/ 39.58

18.3511

31.38 5.54 31-37 5.35 18"62}

44"7

T h e effect o f o z o n e o n p o l y m e r s o f t h i s s t r u c t u r e d o e s n o t r e s u l t in p o l y m e r breakdown; oxidation takes place to give products containing carboxyl groups. 0 z o n i z a t i o n c a n n o t t h e r e f o r e finally solve t h e p r o b l e m o f t h e s t r u c t u r e o f t h i s polymer. EXPERIMENTAL

The polymer studied was obtained by diaeetyl and P D A polyeondensation in 4imethylformamide in the presence of glacial acetic acid. 33.5 g P D A was dissolved in 100 ml dimethylformamide and 26.8 g 4iaeety], in 25 ml glacial acetic acid, was added. The reaction mixture was heated at 70 ° for one hour and at 100-115 ° for three hours. The solution was then decanted into 400 ml hot water, neutralized

344

M. I~T. SHIROKOVA and A. I. YAKUBCI~IK

with potassium hydroxide, the residue separated was filtered, washed with water, ex t r act ed in a Soxhlet apparatus with m e t h y l alcohol, then with ether, and dried. 27.6 g dark-brown amorphous powder was obtained which was soluble in formic and sulphuric acids and dimethylformamide and insoluble in other solvents. The results of elementary analysis are shown in Tables 1 and 2; the Ii~ spectrum is shown in Fig. 1. I t should be noted t h a t the elementary composition of the polymer obtained under the conditions indicated differs from t h a t of the polymer obtained in glacial acetic acid and. in well dried benzene [5, 6]. Ozonizati0n of the polymer was carried out: 1) in ethyl acetate, 2) in a mixture of chloroform with m e t h y l alcohol, 3) in formic acid. I n the second case ozonization was carried out both with a mixture of ozone-oxygen and ozone-argon. Ozonization i n ethylacetate. As the polymer was insoluble in ethyl acetate ozonization was carried out in suspension. DurirLg ozonization in this solvent we were able to determine diacetyl and nitrogen-containing products, b u t could not determine acetic acid since the

bp

C' •~

GO CZ'

~

zo

d' 0

2"g

3"2 m!

FIG. 2. Curves of high-frequency titration: a b c d - - o f the ozonization product o f a polymer, a ' b ' e ' d ' - - o f ar~ ozordzation product oxidized with hydrogen peroxide.

latter is formed by the influence of ozone on the solvent. 0.5010 g polymer was ozonize4 in 100 ml dry ethyl acetate at 0 ° with an oxygen-ozone mixture containing 3.6~o ozone until ozone absorption had ceased. After ozonization, as well as a light-yellow ozonization product, a small amount of the initial polymer was left in the reaction test tube. The ozonization product insoluble in ethyl acetate was separated from the initial polymer; the yield was 0.1268 g. E t h y l acetate was removed i n vacuo (5-8 ram), the residue dissolved in methyl alcohol and precipitated with ether; 0.1502 g of a light-yellow product was obtained. Elem e n t a r y analytical data for both products are shown in Table 2. Their II~ absorption spect r u m was identical with t h a t of the ozorgzation product in formic acid (Fig. 1). Ozonization i n a mixture of chloroform and methyl alcohol. 0.4087 g polymer was ozonized in a m i x t u r e of 120 ml chloroform and 20 ml m e t h y l alcohol at --20 ° tmtil the polymer completely dissolved. The solvent was then removed i n vacuo. The residue was dissolved in m e t h y l alcohol and precipitated with ether. 0.5088 g of a light-brown product was obtained. Under the same conditions ozonization was carried out with a mixture of ozone and argon.

S t r u c t u r e of d i a c e t y l a n d p - p h e n y l e n e d i a m i n e

345

I n f o r m e r e x p e r i m e n t s we u s e d o z o n i z e d o x y g e n w h i c h m i g h t c a u s e m a n y c o m p l i c a t i o n s o w i n g to t h e oxidatiorL of t h e p o l y m e r ir~ p a r a l l e l w i t h ozonolysis. To a v o i d t h i s diff i c u l t y we a d s o r b e d o z o n e o n silica gel a n d t h e n i n t r o d u c e d it to t h e r e a c t i o n , d e s o r p t i o n b e i n g cffected i n a d r y argorL flow [16]. As a r e s u l t o f t h e r e a c t i o n o f t h e p o l y m e r w i t h p u r e ozone, we o b t a i n e d a p r o d u c t w h i c h d i d n o t differ i n e l e m e n t a r y c o m p o s i t i o n and. I R s p e c t r u m f r o m t h e p r o d u c t o b t a i n e d w i t h ozonized oxygen from the polymer. Ozonization of the polymer in formic acid. 0.4024 g p o l y m e r i n 100 m l f o r m i c acid w a s o z o n i z e d a t 0 ° u n t i l t h e eolour o f t h e s o l u t i o n c h a n g e d f r o m d a r k - r e d t o l i g h t - y e l l o w (5 hi'). I t s h o u l d b e n o t e d t h a t a n i n c r e a s e i n t h e o z o n i z a t i o n t i m e t o 8 h r die[ n o t c h a n g e t h e elem e n t a r y compositior~ o f t h e o z o n i z a t i o n product.. A f t e r o z o n i z a t i o n t h e s o l v e n t w a s r e m o v e d in vaeuo (5 8 m m ) a t 30 50 ° t o a v o l u m e o f 3 4 m l a n d t h e r e s i d u e d e c a n t e d i n e t h e r . T h e l i g h t - b r o w n p r o d u c t was r e p e a t e d l y w a s h e d w i t h e t h e r a n d d r i e d i n vacuo. 0.4665 g w a s o b t a i n e d ; t h e i n c r e a s e in w e i g h t of t h e iuitial p o l y m e r s a m p l e w a s 15.9°{). T h e p r o d u c t o b t a i n e d was s e p a r a t e d i n t o f r a c t i o n s soluble a n d i n s o l u b l e i n m e t h y l Meohol. E l e m e n t a r y a n a l y s i s d a t a are g i v e n in T a b l e 2. I1R s p e c t r u m c a n b e s e e n i n Fig. 1. Q u a l i t a t i v e t e s t s for d i a c e t y l a n d acetic a c i d [17, 18] w i t h all t h e s o l v e n t s u s e d a n d in t h e low t e m p e r a t u r e t r a p ( - - 3 0 - - - 4 0 ° ) i n s e r t e d i m m e d i a t e l y a f t e r t h e r e a c t i o n t e s t t u b e , s h o w e d t h e a b s e n c e of t h e s e s u b s t a n c e s . Oxidation o f 0-3362 g o z o r d z a t i o n p r o d u c t o b t a i n e d i n t h e last e x p e r i m e n t was c a r r i e d o u t w h i l e h e a t i n g t o 8 0 - 9 0 ° w i t h 40 m l 7 . 5 % h y d r o g e n p e r o x i d e for 1.5 hi" in a t w o - n e c k e d flask p r o v i d e d w i t h a reflux c o n d e n s e r a n d c a p i l l a r y for p u r e n i t r o g e n flow. Gas was d i v e r t e d t o tlae t r a p c o n t a i n i n g a s o d a s o l u t i o n o f h y d r o x y l a m i n e chloride. T h e r e a c t i o n m i x t u r e w a s h e a t e d u n t i l t h e o z o n i z a t i o n p r o d u c t s a m p l e w a s c o m p l e t e l y dissolved. T h e c o n t e n t s o f t h e t r a p was t h e n e x t r a c t e d w i t h e t h e r a n d , a f t e r d r y i n g , t h e e t h e r was r e m o v e d in vacuo. N o o x i m e s were o b t a i n e d i n t h i s case. I n a n o t h e r e x p e r i m e n t o x i d a t i o n was c a r r i e d o u t b y t h e s a m e m e t h o d . A f t e r t h e r e a c t i o n t e s t t u b e t h e t r a p c o n t a i n i n g c a l c i u m chloride was situated to recover water and then the weighed tube containing askarite. Carbon dioxide l i b e r a t e d d u r i n g o x i d a t i o n was d e t e r m i n e d b y t h e w e i g h t i n c r e a s e of t h e t u b e coIm~ining a s k a r i t e w h i c h was 0.1675 g. A f t e r o x i d a t i o n , w a t e r a n d h y d r o g e n p e r o x i d e were r e m o v e d in vacuo. 0.1961 g o f a light, b r i t t l e p r o d u c t r e m a i n e d w h i c h s t r o n g l y a b s o r b e d m o i s t u r e ; o n h e a t i n g , it d e c o m p o s e d w i t h o u t m e l t i n g . T h e c a r b o x y l c o n t e n t w a s 5 0 . 7 % ( a v e r a g e of t h r e e d e t e r m i n a t i o n s ) . Qualit a t i v e t e s t s i n a q u e o u s s o l u t i o n , a f t e r o x i d a t i o n , s h o w e d t h e a b s e n c e of d i a c e t y l a u d acetic acid. A f t e r p a r t i a l o x i d a t i o n o f t h e a q u e o u s s o l u t i o n t h e h y d r o g e n p e r o x i d e excess was dec o m p o s e d b y p l a t i n u m b l a c k a n d t h e a q u e o u s s o l u t i o n was s u b j e c t e d to d i s t r i b u t i o n c h r o m a t e g r a p h y [19]. A p e a k w a s o b t a i n e d c o r r e s p o n d i n g t o acid o n l y w h i c h was e x t r a c t e d w i t h p u r e b u t y l alcohol. The carboxyl groups i n t h e o z o n i z a t i o n p r o d u c t a n d t h e o z o n i z a t i o n p r o d u c t oxidized w i t h h y d r o g e n p e r o x i d e were d e t e r m i n e d i n a h i g h - f r e q u e n c y t i t r o m e t e r of the. " P u n g o r " t y p e . A m e t h o d o f b a c k t i t r a t i o n w a s u s e d i n d e t e r m i n a t i o n as t h i s g a v e clearer e q u i w d e n t t r a n s i t i o n p o i n t s [20]. 1 0 - 2 0 nag o f t h e s u b s t a n c e w a s d i s s o l v e d i n a n excess of 0-1 ~¢ p o t a s s i u m h y d r o x i d e s o l u t i o n so t h a t a p p r o x . 1 m l 0.1 s h y d r o c h l o r i c acid was u s e d for t h e b a c k t i t r a t i o n o f t h i s excess. 0.1 x h y d r o c h l o r i c acid w a s a d d e d f r o m a m i c r o b u r e t t e in p o r t i o n s of 0.1 m l w i t h v i g o r o u s s t i r r i n g a n d t h e r e a d i n g s of t h e m i c r o a m p e r m c t e r r e c o r d e d . T i t r a t i o n is r e p r e s e n t e d b y a b r o k e n c u r v e abcd (Fig. 2) f o r m e d b y t h e i n t e r s e c t i o n of t h r e e s t r a i g h t lines w h i c h c h a r a c t e r i z e t h e electrical c o n d u c t i v i t y v a r i a t i o n of t h e t i t r a t e d solution. T h e ab s e g m e n t c o r r e s p o n d s to t h e t i t r a t i o n of a n a l k a l i excess, t h e bc s e g m e n t t o t h a t of c a r b o x y l groups, t h e cd s e g m e n t c h a r a c t e r i z e s t h e a p p e a r a n c e of a n a c i d excess in t h e s o l u t i o n .

346

]Yl. N. SHIROKOV-4. a n d A. I. YAKUBCHIK

The product specimens were made into pellets with K B r a n d their I R spectra recorded in an IKS-14 device (prisms o f L i F a n d NaC1). The concentration of the initial polymer a n d ozonization product was 3"6 mg per 2 g K B r , t h a t of the oxidation product 3.0 mg per 2 g K B r .

CONCLUSIONS The chemical structure of a diacety| and p-pheny|enedia~i~e po]ycondensation product was studied by ozonization. The results of ozonization prove that the polymer structure respond to a polymerized Schiff's base

d o e s n o t cor-

(I)

LcH, cH,

J. Translated by E. S E ~ R E

REFERENCES 1. A. H. RIEBEL, R. E. ERICKSON, C. J. ABSHIRE and P. S. BAILEY, J. Amer. Chem. Soe. 82: 1810, 1960 2. A. E. MILLER, J. Organ. Chem. 26: 2327, 1961 3. R. E. ERICKSON, A. H. RIEBEL, A. M. R E A D E R and P. S. BAILEY, Liebigs Ann. Chem. 653; 129, 1962. 4. E. I. MORICONI and F. A. SPANO, J. Amer. Chem. Soc. 86: 38, 1964 5. B. E. DAVYDOV, B. A. KRENTSEL, Yu. A. POPOV and L. V. PROKOF'EVA, Vysokomol. soyed. 5: 321, 1963 6. Yu. A. POPOV, Dissertatsiya (Thesis), 1963 7. L. BELLAMY, Infrakrasnye s p e k t r y slozhnykh molekul. (Infrared Spectra of Complex Molecules.) Izd. inostr, lit., 1963 8. O. DIELS, W. M. BLANCHARD and H. HEYDEN, Ber. 47: 2359, 1914 9. O. DIELS a n d H. IOST, Bed. 35: 3293. 1902 10. G. W. WILLFANG, G F R P a t e n t 932701; R Z h K h i m 24820, 1957 11. V. P. PARINI, Z. S. KAZAKOVA, M. N. OKOROKOVA a n d A. A. BERLIN, Vysokomol. soyed. 3: 402, 1961 12. Yu. V. KISSIN a n d G. M. PSHENITSYNA, Vysokomol. soyed. 5: 1069, 1963 13. V. A. KARGIN, V. A. KABANOV, V. P. ZUBOV and A. B. ZEZIN, Dokl. Akad. Iqauk SSSR 139: 605, 1961 14. SHKODA, SHURTS and BAITSER, K h i m i y a i tekhnol, polimerov 9: 43, 1960 15. H. FRITZSCHE, W. SCHULZE a n d G. LETSCH, Z. Chem. 2: 357, 1962 16. Y. K. W E I a n d R. J. CVETANOVI[~, Canad. J. Chem. 41: 913, 1963 17. F. FEIGL, K a p e l ' n y i analiz organicheskikh veshchestv. (Spot Tests for Organic Subsfances.) Moscow p. 277, 302, 643, 1962 18. K. BAUER, Analiz organieheskikh soyedinenii. (Analysis of Organic Compounds.) Moscow, p. 210, 1953. 19. A. I. YAKUBCHIK and S. K. ZYKOVA, Zh. prikl, khimii 29: 1591, 1956 20. V. A. ZARINSKII and I. A. GUR'YEV, Zavodsk. lab. 29: 1157, 1963 21. M. N. SHIROKOVA and A. I. YAKUBCHIK, Vysokomol. soyed. 7: 1641, 1965