Ring formation in beryllium polysebacyldiacetonate solutions

2200

V.V. KORSHAKet al. REFERENCES

1. L. S. GALBRAITH, V. A. DEREVITSKAYA and Z. A. ItOGOVIN, Vysokomol. soyed. 3: 980, 1961 2. W. KERN and It. S. SCHULZ, Angew. Chcmie. 69: 153, 1957; W. KERN, Chemiker-Ztg. 82: 71, 1958 3. M. M. KOTON, I. V. ANDItEYEVA and Yu. P. GETMANCHUK, Vysokomol. soyed. 4: 1537, 1962 4. D. J. BItIDGEFOItD, Industrial and Engineering Chemistry 1: 45, 1962 5. Z. A. ItO(~OVIN, SUN' TUN, A. D. VIRNIK and N. M. KHVOSTENKO, Vysokomol. soyed. 4: 571, 1962 6. ¥u. (L KRYAZI-IEV, Z. A. ROGOVIN and V. V. CHERNAYA, Sb. Tselluloza i yeye proizvodnye. (Collection. Cellulose and its Derivatives.) Izd. Akad. Nauk SSSR, 94, 1963 7. B. D. COLEMAN and R. M. FUOSS, J. Amer. Chem. Soc. 77: 5472, 1955

RING FORMATION IN BERYLLIUM POLYSEBACYLDIACETONATE SOLUTIONS *~ V. V. KORSHAK, S. V. VINOGRADOVA a n d M. G. VINOGRADOV Institute of Elementary Organic Compounds, U.S.S.R. Academy of Sciences (Received 9 January 1964)

TttE. equilibrium b e t w e e n linear p o l y m e r s a n d cyclic p r o d u c t s was first studied b y Carothers on t h e example of the p o l y m e r i z a t i o n of s i x - m e m b e r cyclic esters [1]. H e also m a d e a detailed s t u d y of the process of t h e r m a l d e p o l y m e r i z a [ i o n of various different h e t e r o c h a i n p o l y m e r s a n d has p r e p a r e d a n u m b e r of macrocyclic esters, formals a n d arahydrides. T h e n the equilibrium b e t w e e n linear a n d cyclic molecules was studied m a i n l y on p o l y m e r s p r e p a r e d b y the p o l y m e r i z a t i o n of cyclic compounds, p a r t i c u l a r l y e-caprolactam. U n d e r equilibrium conditions a p o l y m e r m a y contain cyclic oligomers of various different sizes. F o r instance, f r o m a p o l y m e r p r e p a r e d b y t h e p o l y m e r i z a t i o n of e-caprolactam, besides the original m o n o m e r cyclic dimers, trimers a n d so oll were also separated, right up t o n o n a m e r s [2]. Cyclic trimers, t e t r a m e r s a n d p e n t a m e r s h a v e been isolated from p o l y e t h y l e n e t e r e p h t h a l a t e , a n d after this t h e y were also f o r m e d to t h e same e x t e n t w h e n the p o l y m e r was m e l t e d [3]. T h e r e are only a few works [4-7] dealing with t h e s t u d y of the equilibrium b e t w e e n p o l y m e r s a n d heterocycles in solution. T h e y are all concerned with * Vysokomol. soyed. 6: No. ll, 1987-1991, 1964. t XXI paper in the series "Investigation in the field Of coordination polymers".

Ring formation in beryllium polysebacyldiaeetonate solutions

2201

equilibrium in solutions of polymers prepared by the polymerization of lowmolecular (3 to 8 member) heterocycles: cyclic oxides, formals and lactams. The literature contains no information on the polymer-macrocycle equlibrium in solution for polymers prepared b y polyeondensation. Under the collditions irt which exchange reaction could occur between the polymer chain units it would be reasonable to expect that these heterochain polymers would also be degraded in dilute solutions with the formation of macroeyelie compounds. It, seems likely that the size of the rings formed would be determined both by thermodynamic and energy factors. From the thermodynamic point of view the size of the rings should be at a minimum since the entropy of the system will be at its maximum in this case. At the same time the formation of the minimum stress rings is energetically most favourable, which means that their magnitude will also depend on the structure of the starting polymer. As we found in an earlier work [8], exchange reactions between the units of the intracomplex polymer prepared by the polycoordination of 4,4'-bis(aeetoacetyl)diphenyloxide and beryllium acetylaceto~tate take place at high rate even at temperature below 100 °. It was therefore suggested that polymeric compounds of bis-(fl)-diketones with beryllium would easily be degraded in dilute solutions with the formation of cyclic products. To test this proposition we have studied the behaviour in solution1 of beryllium polysebacyldiacetonate (BPS) prepared by the polyeondensation of sebacyldiaeetonate with beryllium acetylacetouate H~C \\

/

CH~

OH 0 0 OH C--O 0 =C I II 11 I S ~/ \ r~ (HaC =CH--C(CH~)sC--CH--CCHa+n CH Be CH-~ ,

\

/

/\

C=O

//

O--C

\

HsC I- H..C , \

/

C--O •

--> i_

~" CH \ ---c

O=C

\/ Be /\ o

CH~

OH.

-

0

\ OH //

II

0

II

+ 2n CHs--C--CH~--C---CHa

o--c--(cmL

To prepare the high-molecular BPS we used the procedure which we have already described in [10] for the polyeoordination of 4,4'-bis-(acetoacetyl) diphenyloxide with berylium acetylaeetonate. It consists i~1 the heating of the starting materials in a high-boiling solvent i n v a c u o followed by heating the polymer without the solvent. The synthesized BPS specimens have a logarithmic viscosity iit ehlorobenzene between 0.5 and 1.2. Our experiments with BPS showed that when heated in dilute solutions in various different organic solvents, this polymer is degraded. On the other hand,

2202

V.V. KOI~SHAKet al.

if heated under exactly the same conditions after evaporation of the solvent, the degradation products once again t u r n into a high molecular polymer. For example, ff a BPS with t/in=0.47 is heated for 2 hr at 130 ° in a 0 . 5 ~ solution, its logarithmic viscosity falls to 0.03, and after the ehlorobenzene has been evaporated and the degradation products heated in the molten state a* exactly the same temperature, a polymer with ~hn=0.55 is formed once again.

08

40

o

0.4

20

I

0

20

....

I

80 Ooncentn~ztfon, %

FzG. 1.

I

100

.

0

I

2

[

8 Ooncentpat/on , %

I

10

Fro. 2.

FId. 1. Degradation of BPS in solutions of various concentrations at 130° (chlorobenzone as solvent). FrG. 2. Yield of cyclic complex I as a function of the concentration of BPS solution in chlorobenzeno at 150°.

Figure 1 shows the logarithmic viscosity of BPS after heating in solution in chlorobenzene of different concentrations and 130 ° until the establishment of equilibrium (approx. 2 hr). I t can be seen t h a t where the BPS solutions are highly concentrated there is no reduction in molecular weight, but as from a concentration of approx. 70°fie it starts to fall, and leads to the degradation of the polymer. As determined by the Fritz method [11] of titration with sodium methoxide, the number of end enol groups in the system ramains unchanged after degradation (acid No. of BPS per mg CII, ONa/g specimen-----44.7 and 44.8 before degradation, and 45.2 and 45.5 after). This means t h a t the reversible degradation of BPS found in ehlorobenzene could, according to the above proposition, be due to intramolecular exchange reactions oceuring at the Be--O bonds in the dilute solutions with the formation of cyclic oligomers which are polymerized on melting and transformed back into the original polymer. On this basis the degradation of BPS in organic solvents should lead to the formarion of a macrocyclic monomerie complex of sebacyldiacetone with beryllium (I):

Ring formation in beryllium polyseba,eyldia,c(~'tonatcsolut,ions

22(13

(CH~)~: //

c--o

CK

\ /

H3C

C=O

\/ Be

/\

o=c

\ CH

//

(I)

O--C

\ CH3

This compound was prepared recently by Kluiber and Lewis [9] as the mtly product of the thermal degradation of low-molecular weight BPS i n v a c u o . To obtain detailed information oll the properties of the macroeyclic complex I, we repeated the experiments of these authors and found t h a t as a result of heating of BPS at 160-200 ° i n v a c u o (0.2 to 0.05 mm) it is in fact the monomerio complex I which is formed exclusively. Its yield is 9 5 ~ . But, in contrast to the fign~res obtained in the work cited, according to which compound I has m.p. 139-140.5 °, both before pul'ification and after recrystallization from methalml at --80 ° followed by sublimation at 75 ° in vacuum of 10 -a to l0 -4 ram, our product had no particular melting point, but melted gradually between 85 and 130 °, passing over to a polymer with logarithmic viscosity 0.8. Of course, the polymerization of the cyclic complex occurred at a temperature lower t h a n the melting range. This means t h a t the melting point of compound I given in [9] seems to be erroneous. The cyclic monomer has quite good solubility in all organic solvents. Its solubility in methanol at room temperature i~t approx. 5 °fie. To find out whether complex I would be formed whe~l dilute BPS solutions were heated in organic solvents, the products of the degradation of the polymer were extracted in methanol, and the residue obtained after evaporation of the solvent at room temperature was heated in a sublimation apparatus in vacmtm ~f 10 -3 to 10 -4 mm at 75 °. The material which sublimed as a white powder was identical in molecular weight and properties with the compound prepared by the thermal degradation of BPS, and must therefore be the cyclic monomeric complex I. The compound separated had a cryoscopic molecular weight of 290 (the molecular weight of complex I was calculated as 289), it contained no enol groups (negative qualitative reaction with iron chloride) and melted between 85 and 130 °, passing over to the polymer with logarithmic viscosity 0.55. The amount of the monomerie complex formed as a result of the degradation of BPS in organic solvents depends on the conditions of degradation, and primarily on the polymer concentration of the solution. Figure 2 shows the yield of beryllium sebaeyldiaeetonate as a function of the BPS concentration in chlorobenzene after the solution had been heated at 150 ° until the establishment of equilibrium. I t is evident fl'om this Figure t h a t a reduction of less t h a n o='/o~ in the concentration of the solution gives a big increase in the yield of cyclic monomer. From the figures given below it follows t h a t the amomlt of cyclic complex formed in dilute BPS solution increases rapidly with rising temperatm'e. The

2204

V.V. KOttSHAK et al.

h e a t i n g time at each t e m p e r a t u r e was r a t h e r more t h a n t h a t f o u n d in control e x p e r i m e n t s for t h e e s t a b l i s h m e n t of e q u i l i b r i u m i n t h e s y s t e m . T h e y i e l d o f cyclic m o n o m e r as d e p e n d e n t o n t h e t e m p e r a t u r e for t h e deg r a d a t i o n of B P S i n 0 . 5 ~ s o l u t i o n ( c h l o r o b e n z e n e ) is as follows: Temp, °C Time, hr Yield, ~

75 20 4

100 10 8

125 6 27

150 2 41

T h e n a t u r e of t h e s o l v e n t also a f f e c t s t h e y i e l d o f t h e cyclic m o n o m e r . F o r i n s t a n c e , d e g r a d a t i o n o f B P S a t 150 ° i n 0 . 5 % s o l u t i o n s p r o d u c e d t h e f o l l o w i n g y i e l d s o f m o n o m e r i c c o m p l e x : i n b e n z e n e 33°ffo, i n c h l o r o b e n z e n e 4 1 ~ a n d i n p - x y l e n e 49~o. The presence of b e r y l l i u m s e b a c y l d i a c e t o n a t e in the d e g r a d a t i o n p r o d u c t s o f B P S i n d i l u t e s o l u t i o n t h u s s h o w t h a t t h e r e a s o n for t h e r e v e r s i b l e c h a n g e s i n t h e m o l e c u l a r w e i g h t of B P S i n o r g a n i c s o l v e n t s lies i n t h e p r o c e s s e s of t h e formation and polymerization of macrocyclic compounds.

EXPERIMENTAL Sebacyldiacetone (2,4,13,15-tetraketohexadecane) was synthesized as follows: to a solution of 25.8 g (0.1 mole) diethylsebacinate and 11-6 g (0-2 mole) acetone in absolute ether are added 16 g (0.41 mole) portions of ground sodium amide with vigorous stirring, the temperature of the reaction mixture being kept at approx. 10°; then the mixture is stirred overnight. After 24 hr the reaction mixture is poured into iced water and the ester layer is discarded. The aqueous layer is treated with excess NattCOa, the deposit formed is separated and extracted in ether. The yield of unpurified sebacyldiacetone was 10 g. After recrystallization from petroleum ether and twice from methanol, the product had m.p. 76-76.5 ° (78 to 78.5 ° according to [9]). BeryUium polysebacyldiacetonate (BPS). 2 g sebaeyldiacetone, 1-47 g beryllium acetylacetonate and 10.5 ml ditolylmethane or 9.8 ml dinyl (a mixture consisting of 73'5~o diphenyloxide and 26.5~/o diphenyl) were placed in the condensation test tube and heated at 100 ° in a nitrogen flow until a solution was formed; then the temperature was raised over a period of an hour up to 160 ° a n d heating continued at this temperature. After 4 hr the test tube was connected up to a vacuum system in which a residual pressure of 30-35 m m was maintained, and the reaction carried on for 8 hr in vacuo. The polymer was precipitated from the solution in petroleum ether, the mixture being cooled in dry ice and acetone, then it was washed with the precipitator and dried at room temperature in vacuo to remove the petroleum ether; after this the polymer was heated gradually in vacuo (1 ram) up to 160 ° and held at this temperature for 3 hr. The beryllium polysobacyldiacetonate had a logarithmic viscosity between 0-5 and 1.2 and was a transparent light yellow elastic mass with a softening temperature of approximately 35 °, which is consistent with the published figures [9]. I t is soluble in benzene, chlorobenzene, chloroform and dimethylformam,ide; it is insoluble in petroleum ether and methanol. I n all cases the logarithmic viscosity of the polymer was measured at 20 ° in chlorobenzene for a solution with a concentration of 0.5 g/ml. Degradation of B P S in organic solvents. The degradation was performed in ampoules in nitrogen atmosphere. After it had finished the solvent was evaporated off at room temperature using a fan.

Plasticization of cellulos~

2205

CONCLUSIONS

(1) H i g h - m o l e c u l a r beryllium p o l y s e b a c y l d i a c e t o n a t e has been synthesized by polycondensation. (2) A new m e t h o d has been f o u n d for p r e p a r i n g macrocyclic c o m p o u n d s ; it consists in the h e a t i n g of the dilute solutions of the p o l y m e r u n d e r conditions in w h i c h e x c h a n g e r e a c t i o n can t a k e place b e t w e e n the units of the polymeric chains. (3) The c o n c e n t r a t i o n , t e m p e r a t u r e a n d n a t u r e of t h e solvent h a v e been s t u d i e d as affecting the yield of m a c r o c y c l i c complex of sebacyldiacetone with beryllium as a result of the d e g r a d a t i o n of beryllium p o l y s e b a c y l d i a c e t o n a t e in organic solvents. REFERENCES 1. W. H. CAROTHERS, G. L. DOROUGH and F. J. van NATTA, ,I. Amer. Chem. Soc. 54: 761, 1932 2. M. ROTHE, J. Polymer Sci. 30: 227, 1958 3. J. GOODMAN and B. F. NESBITT, Polymer 1: 384, 1960 4. A. A. STREPIKHEYEV, Dissertation, 1950 5. A. A. STREPIKHEYEV and A. V. VOLOKHINA, Dokl. Akad. Nauk SSSR 99: 407, 1954 6. D. J. WORSFOLD and A. M. EASTHAM, J. Amer. Chem. Soc. 79: 897, 900, 1957 7. H. YUMOTO, Bull. Chem. Soc. Japan. 28: 101, 1955 8. V. V. KORSHAK, S. V. VINOGRADOVA and M. G. VINOGRADOV, Vysokomol. soyed. 6: 729, 1964 9. R. W. KLUIBER and J. W. LEWIS, J. Amer. Chem. Soc. 82: 5777, 1960 10. V. V. KORSHAK, S. V. VINOGRADOVA and M. G. VINOGRADOV, Vysokomol. soyed. 5: 1771, 1963 ll. I. S. FRITZ, Analyt. Chem. 24: 674, 1952

PLASTICIZING

CELLULOSE

BY

POLYBUTYL

R. M. LIVSHITS,

A. A. FROLOVA,

GRAFTING

POLYMETHYL

AND

ACRYLATE *t

P. V. KOZLOV

and Z. A. ROGOVIN

Moscow Textile Institute, Moscow State University (Received 9 Ja~uary 1964)

W E HAVE a l r e a d y studied t h e plasticization of cellulose n i t r a t e b y grafting p o l y m e t h y l a c r y l a t e [1]. I t was f o u n d t h a t if the g r a f t c o p o l y m e r i z a t i o n was p e r f o r m e d u n d e r conditons in which the original p o l y m e r shows considerable * Vysokomol. soyed. 6: No. 11, 1992-1996, 1964. t 163rd paper from the series "Investigation of the structure and properties of celluloso and its ~erivatives".