- Email: [email protected]
Synthesis and microstructure of organotin polymers
1074
V . A . ZUBOV et al.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.
T. V. NIKOLAYEVA and A. Ye. KULIKOVA, Plast. massy No. 4, 12, 1985. Patent application 56-90820 Japan. RZhKhim. 15C: 542, 1982. Patent application 57-36101 Japan. Ibid 12C: 404 H, 1983. L. M. SHEVCHUK, Ye. N. MIL'CHENKO, I. N. VISHNEVSKAYA, A.B. ZATTSEV and A. Ye. KULIKOVA, Vysokomol. soyed. B20: 897, 1978 (not translated in Polymer Sci. U.S.S.R.). V. V. LISOVTSEV and A. Ye. KULIKOVA, Fiziko-khimicheskiye osnovy sinteza i pererabotki polimerov (Physicochemical Bases for the Synthesis and Processing of Polymers) p. 76, Gorkii, 1984. Praktikum po kolloidnoi khimii (Practicum on Colloidal Chemistry) (Ed. R. E. Neuman) p. 46, Moscow, 1972. D. KAY, Tekhnika elektronnoi mikroskopii (Technique of Electron Microscopy) p. 86, Moscow, 1965. P. R. SPERRY, H. B. HOPFENBERG and N. J. THOMAS, Colloid, Interface Sci. 82: 62, 1981. V. V. SHEBYREV, A. D. GUTKOVICH, E. P. RIBKIN and V.A. KAMINSKII, Tez. dolk. konf. "Khimreaktor-8". (Summaries of Reports to Conference "Chemreactor-8") Vol. 2, p. 359, Chimkent, 1983.
PolymerScience U.S.S.R. Vol. 32, No. 6, pp. 1074-1079,1990 Printed in GreatBritain.
0032-3950/90$10.00+ .00 © 1991PergamonPresspie
SYNTHESIS AND MICROSTRUCTURE OF ORGANOTIN POLYMERS* V. A . Z t J B o v , W . WOLF a n d V. B. KONSULOV Higher PedagogicInstitute, Shumen, Bulgaria (Received 25 February 1989)
IR spectroscopy and derivatography have been used to analyse the intramolecular conversions of the b/s-tri-n-butyistannyl esters of maleic and fumaric acids and also their copolymers. Thermal isomerization of the maleates to fumarates does not occur up to temperatures of the onset of decomposition of the substances. On free-radical copolymerizationof the maleates with styrene there is partial isomerization and in the structure of the chain, units of the diesters of maleic (85-90%) and fumaric (10-15%) acids are found. In the alternating styrene-maleic anhydride copolymersafter esterification by organotin oxides the number of isotactic diads may be 10%. Change in the microtacticityis explained by the formation of polycarbanions. Heating of the copolymersto 500 K leads to exothermal change in the configurationof the maleate units and then to their cyclizationwith the formation of maleic anhydride units. THE ORGANOTIN esters of fumaric (I) and maleic (II) acids are used in the synthesis of biostable copolymers [1, 2]. It is natural to assume that in the course of radical polymerization the thermodynamically stable form I must lead to the formation of the syndiotactic configuration of the unit (III); the thermodynamically labile form II may lead both to isotactic (IV) and syndiotactic (III) configurations if during polymerization maleic acid is isomerized to fumaric. In the final analysis this is reflected in the biostability of the copolymers [3] *Vysokomol. soyed. A32: No. 6, 1144-1149, 1990.
Synthesis and microstructure of organotin polymers
1075
, A, I cH t. C[OOSnRa
An
III
[ oos. 3 coos. 3jo IV The aim of the present work is synthesis of the copolymers of organotin esters of maleic and fumaric acids and exploration of their microstructure. The monomers I and II were obtained by the technique of reference [4], TMF = 394--396 and 322 K, respectively. Styrene was distilled, BP 419 K. Copolymerization of compounds I and II with styrene was effected at 333 K for 2 h and at 353 K for 4 h in presence of 0.1% by weight AIBN. Copolymer II-styrene (V) was twice reprecipitated from benzene into petroleum ether, copolymer I-styrene (VI) from benzene to ethanol and dried at 333 K. The tin content of compound V was 4.7 + 0.1 and of compound VI 2.2 + 0.1% by weight. The styrene-maleic anhydride copolymer was obtained by copolymerization in benzene at 333 K for 4 h, washed with benzene and esterified with tri-n-butyltin oxide (VII) by the technique of reference [5]. The reaction mass assumed a yellow colour which disappeared on reprecipitation of compound VII into acetone. The tin content of this copolymer was 28.7 ___0.3% by weight. Poly-tri-n-butyltin methacrylate (PTBTM) was obtained by the technique of reference [6] at 333 K (VIII). The polymers were hydrolysed in the system dioxane-acetone-water with hydrochloric acid at 293 K. The hydrolysed polymers were purified by reprecipitation from dioxane into water. The IR spectra were recorded with the Specord IR-75 spectrophotometer and the derivatograms on the Q-derivatograph of the Paulic system (model 3428). For certain conformations of organotin monomers and polymers the tin atom, because of the presence of a vacant d-orbital, may enter into interaction with different nucleophilic centres [5, 7] with the formation of five- and six-coordination structures. As shown in reference [5] the presence of absorption in the region 1660-1620 cm -~ clearly points to coordination but absorption in the region 1580-1530 cm -1 to its absence. In the IR spectrum of compound II (Fig. 1) a doublet is present at 1640 and 1630 cm -1 of average intensity and a strong band at 1550 cm -1. In view of the fact that in the region 1630-1640 cm -~ Uc=c and Vc=o become manifest (COOSnR3 groups) we carried out investigations aimed at elucidating the nature of these bands. Analysis of the changes occurring in the IR spectra of the monomer II on heating to 473 K showed that with rise in temperature the intensity of the band at 1550 cm -~ decreases and at 473 K it disappears completely (Fig. 2). Over the entire temperature interval the intensity of the doublet bands remained constant but the position of the band at 1630 cm -~ on heating of the substances shifted to the low frequency region to 1620 cm-1. After cooling compound II its spectrum matched that of the initial sample. Evidently the changes observed in the IR spectra are not a consequence of isomerization of maleic to fumaric acid but a consequence of the different coordination of different conformers HC CH HC CH
\c-osl. \
I , /\ OSn ... 0 I
293 K (IX)
, C/
\ c
°
0 \\
....
0
f
Sn ..- 0 /1\ 473 K (X)
1076
V . A . ZUBOV et al. 1
17
74 v × 70 2, c m
FIG. 1. FIO. 2.
7
/7
lZ/
17
fl/
v x 10 -2, crn -~
Flo. 2 FIG. 1 IR spectra of b/s-tri-n-butylstannyl ester of fumaric (1), maleic (2) and succinic (3) acids. Suspensions in vaseline oil. IR spectra of the b/s-tri-n-butylstannyi ester of maleic acid. Temperature 293 (1), 403 (2), 473 K (3). (4) same as (3) after cooling to 293 K.
Four-coordination tin in compound IX is characterized by the band 1550 cm-t, five-coordination tin by 1630 cm -1 and in compound X there is only five-coordination tin (1620 cm -1) since the band at 1550 cm -1 is absent. In the spectrum of monomer I there are no absorption bands in the region 1660-1620 cm -1 indicating the absence of coordination in this compound. Its spectrum is similar to that of the organotin derivative of succinic acid for which intra-molecular coordination cannot be realized. Absence of isomerization also stems from the results of derivatographic investigations (Fig. 3). On heating the monomer II to the temperature of thermal degradation ( ~ 473 K) in the DTA curve after the melting peak (322 K) two exo-effects are present, oxidation (520-530 K) and change in the conformation II by the scheme (1) (473-500 K). This exo-effect confirms the presence in the monomer II of intramolecular coordinations stabilizing the conformers IX and X. Intermolecular coordination for them is thermodynamically disadvantageous since it leads to more open, unfolded conformations. Thus, monomer II is stable to thermal isomerization which contradicts the statement of the authors of references [1, 9] on the ease of its isomerization to the monomer I already occurring at room temperature. It may from all this be assumed that on heating the reaction mixture of the monomers I-styrene and II-styrene to 333 and 353 K thermal isomerization of compound II to monomer I does not occur which, however, gives no grounds for asserting that isomerization will not occur on initiation of polymerization via the free-radical mechanism. To elucidate isomerization in the course of polymerization the copolymers I-styrene and II-styrene were subjected to chemical conversions by the schemes (2) and (3) for the compounds V and VI, respectively o __Cj --COOSnRa HCl --COOH (2) \0 --COOSnRa --COOH --H,O __C/ %0
Synthesis and microstructure of organotin polymers
RsSnOOC--~
.rrcl~ HOOC--
I--COOSnRs
1077
> --O--C[ - --COOH
-/t,o
0
(3)
--C--O-
Il 0 According to these schemes the absence of isomerization of II on copolymerization with styrene must give an isotactic configuration of the unit which after hydrolysis and thermal dehydration will give the elementary units of the cyclic anhydride [Vc=o = 1865 (sym) and 1785 (asym) cm -1 [10]]. If isomerization occurs there must form the syndiotactic configuration of the unit which on dehydration will lead to the formation of acyclic anhydride structures [Vc=o--1787 (sym) and 1750 (asym) cm -1 [10]]. Figure 4 presents the IR spectra of films of hydrolysed organotin copolymers recorded at different temperatures. It will be seen that in the film of the hydrolysed polymer V on heating, the band at 1730cm -1 (Vc=o) of the carboxyl group disappeared and two bands appeared at 1860 and 1785 cm -1 indicating the formation of cyclic anhydride structures. In the film of the hydrolysed polymer VI heated to 523 K bands appeared at 1785 and 1750 cm -1. The position of the bands and their intensity ratio point to the formation of acyclic anhydride structures [10]. +IT
'"--, _,/" III
-~-
(a) ¢785
1785
~) t~
~ l
I II
,.t73 473
Fio. 3
I
l
673 773 7';,/<
'27
1785 3
FxG. 4
FIO. 3. Derivatogramsof bis-tri-n-butylstannyl ester of fumaric(1) and maleic (2) acids. Weighedbatch 98 mg, sensitivity100 mg, heating rate 10 degrees/rain. The sensitivityof the DTA and DTG methods is 1/10. Speed of recording2 ram/rain. Referencealuminiumoxide; mediumair. Fio. 4. Changesin the bandsof the IR spectraof filmsof the copolymersV (a) and VI (b) firstsubjectedto hydrolysison their heating.Temperature273 (1), 303 (2), 483 (3) and 523 K (4). Analysis of the spectra of the hydrolysed polymers V subjected to dehydration shows that during copolymerization of the monomer II with styrene its partial isomerization nevertheless occurs. Quantitative determination of the carboxyl groups (1727 cm -1) not entering into the dehydration reaction and not leading to the formation of the anhydride amounts to 10-15%. Many authors have noticed that the interaction of the styrene-maleic anhydride copolymer with bases, in particular, with tri-n-butyltin oxide, is accompanied by the appearance of an intense purple colour of the reaction mass [5, 11-13], such coloration disappearing on acidification of the medium. Therefore, doubt has been cast on the correctness of the interpretation of the microstructure of the organotin derivatives of maleic anhydride copolymers.
1078
V . A . ZuBov et al.
In the films of HCl-hydrolysed copolymer VII on heating, both units of maleic anhydride (1860 and 1785 cm -1) and acyclic anhydride structures 1785 and 1750 cm -1) were detected. The number of maleic anhydride units tentatively calculated from the intensity ratio of these bands, i.e. isotactic diads in the polymer VII, was - 1 0 times less than for the fumaric acid units, i.e. syndiotactic diads. In accord with reference [14, p. 551] the appearance of purple coloration of the solutions with absorption maximum at 560 nm may point to the formation of carbanions capable of changing as a result of their s p 2 state the configuration of the units, i.e. promoting change in the microtacticity of the polymers with C - - H acid centres H--C--COOSnRs +B:
-C--C00SnRs
H--/--COOSnRsC- B d
H - - CI - - C O O S n R s
q-Brt
RsSnOOC--C-
>
I-I--C--COOSnRa I
'
XI RsSnOOC--C--H
>
I
H--C--COOSnRs
+B:
(4)
XII
Modelling of the structures XI and XII in the copolymer chains taking into account intramolecular coordinations with the aid of Stewart-Brigleb ball-rod models confirms the possibility of change in microtacitity according to the scheme (4). Figures 5 and 6 give the derivatograms and IR spectra of the copolymers VII and VIII. As may be seen from the former in the region 473--500 K exoeffects are observed interpreted as intramolecular regroupings similar to the conversion of compound IX to the structure X by the scheme (1). As follows from the derivatograms the newly formed structures X are unstable and with further rise in temperature are destroyed with the formation of maleic anhydride units (Fig. 6, absorption at 1785 and 1860 cm-1). According to 13C NMR the content of the isotactic diads in the polymer VIII is 4-8% [6] and according to the results of the derivatographic investigations a value />4.7% is obtained practically matching this interval. The lower temperatures of the breakdown of the isotactic diads in the polymer VIII (443--473 K) as compared with the diads in the copolymer VII (483-503 K) may be explained by the presence in
5
3
3 ~
I
i
I
473
F1o. 5 Flc. 5.
I
673
I
"/':,K
2
l
i
i
;'8
16
~
v X 10 -2, c m -7
Flo. 6
Derivatograms of the polymers VIII (1, 2) and VII (3, 4): 1, 3, DTG; 2, 4, DTA. Sensitivity of the DTA method 1/3. Heating rate 5 degrees/min. Reference aluminium oxide; medium air. Fic. 6. IR spectra of polymers VII (1), VII at 423 K after 15 rain (2); VII at 473 K after 15 rain (3) and VIII (4) and VIII at 463 + 10 K after 15 min (5).
Synthesis and microstructure of organotin polymers
1079
the diads of VIII of methyl groups possessing a +I-effect and, thereby, lessening the polarity of the linkage of the polyanions with the tin cations which makes the linkage with the polymer chain less stable than in the copolymer VII.
Translated by A. Cl~ozv
REFERENCES 1. D. A. KOCHKIN, Obrastaniye i biokorroziya v vodnoi srede. Biologicheskiye povrezhdeniya. (Fouling and Biocorrosion in an Aquatic Medium. Biological Damage) p. 164, Moscow, 1981. 2. H. IMAZAKI, Y. KITANO, T. KITAO, S. MURAKANI and H. DOI, Patent 381275 Sweden. RZhKhim 4T638, 1977. 3. V. F. MISCHENKO and V. A. ZUBOV, Vysokomol. soyed. B24: 184, 1982 (not translated in Polymer Sci.
U.S.S.R.). 4. Z. M. RZAYEV, Zh. obshch, khim. 39: 544, 1969. 5. V. F. MISHCHENKO and V. A. ZUBOV, Vysokomol. soyed. A25: 2061, 1983 (translated in Polymer Sci. U.S.S.R. A25: 10, 2389, 1983). 6. B. B. DAMBATTA and J. R. EBDON, Brit, Polymer J. 16: 69, 1984. 7. S. Ya. KHORSHEV, A. I. YEGOROCHKIN and Ye. I. SEVAST'YANOVA, Khimiya elementoorganicheskikh soyedinenii (Chemistry of Elemento-organic Compounds) p. 3, Gorkii, 1980. 8. S. DIETZELS, K. JURKSCHAT, A. TZSCHACK and A. ZSCHUNKE, Z. anorgan, und allgem. Chem. 537: 163, 1986. 9. D. A. KOCHKIN, O. K. BOTCHENKO and G.A. KURAKOV, Stroyeniye veshchestva i fizikokhimicheskii analiz (Structure of Matter and Physico-chemical Analysis) p. 102, Kalinin, 1973. 10. K. NAKANISI, Infrakrasnye spektry i stroyeniye organicheskikh soyedinenii (Infra-Red Spectra and Structure of Organic Compounds) p. 216, Moscow, 1965. 11. N. K. BARAMBOIM and R. G. FOMINA, Trud. Inst. legkoi prom-sti No. 33, 126, 1967. 12. B. L. MOLDEVSKII and Yu. D. KERNOS, Maleinovyi angidrid i maleinovaya kislota (Maleic Anhydride and Maleic Acid) p. 88, Leningrad, 1976. 13. Gy. HARDY, G. KOVACS, H. BOUDEVSKA and V. NEITCHEV, Tez. kr. soobshch. Mezhdunar. simp. po makromolekulyarnoi khimii (Summaries of Brief Communications. International Symposium on Macromolecular Chemistry) Vol. 4, Tashkent, 1978. 14. Obshchaya organicheskaya khimiya (General Organic Chemistry) Vol. 1, p. 736, Moscow, 1981.
V . A . ZUBOV et al.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.
T. V. NIKOLAYEVA and A. Ye. KULIKOVA, Plast. massy No. 4, 12, 1985. Patent application 56-90820 Japan. RZhKhim. 15C: 542, 1982. Patent application 57-36101 Japan. Ibid 12C: 404 H, 1983. L. M. SHEVCHUK, Ye. N. MIL'CHENKO, I. N. VISHNEVSKAYA, A.B. ZATTSEV and A. Ye. KULIKOVA, Vysokomol. soyed. B20: 897, 1978 (not translated in Polymer Sci. U.S.S.R.). V. V. LISOVTSEV and A. Ye. KULIKOVA, Fiziko-khimicheskiye osnovy sinteza i pererabotki polimerov (Physicochemical Bases for the Synthesis and Processing of Polymers) p. 76, Gorkii, 1984. Praktikum po kolloidnoi khimii (Practicum on Colloidal Chemistry) (Ed. R. E. Neuman) p. 46, Moscow, 1972. D. KAY, Tekhnika elektronnoi mikroskopii (Technique of Electron Microscopy) p. 86, Moscow, 1965. P. R. SPERRY, H. B. HOPFENBERG and N. J. THOMAS, Colloid, Interface Sci. 82: 62, 1981. V. V. SHEBYREV, A. D. GUTKOVICH, E. P. RIBKIN and V.A. KAMINSKII, Tez. dolk. konf. "Khimreaktor-8". (Summaries of Reports to Conference "Chemreactor-8") Vol. 2, p. 359, Chimkent, 1983.
PolymerScience U.S.S.R. Vol. 32, No. 6, pp. 1074-1079,1990 Printed in GreatBritain.
0032-3950/90$10.00+ .00 © 1991PergamonPresspie
SYNTHESIS AND MICROSTRUCTURE OF ORGANOTIN POLYMERS* V. A . Z t J B o v , W . WOLF a n d V. B. KONSULOV Higher PedagogicInstitute, Shumen, Bulgaria (Received 25 February 1989)
IR spectroscopy and derivatography have been used to analyse the intramolecular conversions of the b/s-tri-n-butyistannyl esters of maleic and fumaric acids and also their copolymers. Thermal isomerization of the maleates to fumarates does not occur up to temperatures of the onset of decomposition of the substances. On free-radical copolymerizationof the maleates with styrene there is partial isomerization and in the structure of the chain, units of the diesters of maleic (85-90%) and fumaric (10-15%) acids are found. In the alternating styrene-maleic anhydride copolymersafter esterification by organotin oxides the number of isotactic diads may be 10%. Change in the microtacticityis explained by the formation of polycarbanions. Heating of the copolymersto 500 K leads to exothermal change in the configurationof the maleate units and then to their cyclizationwith the formation of maleic anhydride units. THE ORGANOTIN esters of fumaric (I) and maleic (II) acids are used in the synthesis of biostable copolymers [1, 2]. It is natural to assume that in the course of radical polymerization the thermodynamically stable form I must lead to the formation of the syndiotactic configuration of the unit (III); the thermodynamically labile form II may lead both to isotactic (IV) and syndiotactic (III) configurations if during polymerization maleic acid is isomerized to fumaric. In the final analysis this is reflected in the biostability of the copolymers [3] *Vysokomol. soyed. A32: No. 6, 1144-1149, 1990.
Synthesis and microstructure of organotin polymers
1075
, A, I cH t. C[OOSnRa
An
III
[ oos. 3 coos. 3jo IV The aim of the present work is synthesis of the copolymers of organotin esters of maleic and fumaric acids and exploration of their microstructure. The monomers I and II were obtained by the technique of reference [4], TMF = 394--396 and 322 K, respectively. Styrene was distilled, BP 419 K. Copolymerization of compounds I and II with styrene was effected at 333 K for 2 h and at 353 K for 4 h in presence of 0.1% by weight AIBN. Copolymer II-styrene (V) was twice reprecipitated from benzene into petroleum ether, copolymer I-styrene (VI) from benzene to ethanol and dried at 333 K. The tin content of compound V was 4.7 + 0.1 and of compound VI 2.2 + 0.1% by weight. The styrene-maleic anhydride copolymer was obtained by copolymerization in benzene at 333 K for 4 h, washed with benzene and esterified with tri-n-butyltin oxide (VII) by the technique of reference [5]. The reaction mass assumed a yellow colour which disappeared on reprecipitation of compound VII into acetone. The tin content of this copolymer was 28.7 ___0.3% by weight. Poly-tri-n-butyltin methacrylate (PTBTM) was obtained by the technique of reference [6] at 333 K (VIII). The polymers were hydrolysed in the system dioxane-acetone-water with hydrochloric acid at 293 K. The hydrolysed polymers were purified by reprecipitation from dioxane into water. The IR spectra were recorded with the Specord IR-75 spectrophotometer and the derivatograms on the Q-derivatograph of the Paulic system (model 3428). For certain conformations of organotin monomers and polymers the tin atom, because of the presence of a vacant d-orbital, may enter into interaction with different nucleophilic centres [5, 7] with the formation of five- and six-coordination structures. As shown in reference [5] the presence of absorption in the region 1660-1620 cm -~ clearly points to coordination but absorption in the region 1580-1530 cm -1 to its absence. In the IR spectrum of compound II (Fig. 1) a doublet is present at 1640 and 1630 cm -1 of average intensity and a strong band at 1550 cm -1. In view of the fact that in the region 1630-1640 cm -~ Uc=c and Vc=o become manifest (COOSnR3 groups) we carried out investigations aimed at elucidating the nature of these bands. Analysis of the changes occurring in the IR spectra of the monomer II on heating to 473 K showed that with rise in temperature the intensity of the band at 1550 cm -~ decreases and at 473 K it disappears completely (Fig. 2). Over the entire temperature interval the intensity of the doublet bands remained constant but the position of the band at 1630 cm -~ on heating of the substances shifted to the low frequency region to 1620 cm-1. After cooling compound II its spectrum matched that of the initial sample. Evidently the changes observed in the IR spectra are not a consequence of isomerization of maleic to fumaric acid but a consequence of the different coordination of different conformers HC CH HC CH
\c-osl. \
I , /\ OSn ... 0 I
293 K (IX)
, C/
\ c
°
0 \\
....
0
f
Sn ..- 0 /1\ 473 K (X)
1076
V . A . ZUBOV et al. 1
17
74 v × 70 2, c m
FIG. 1. FIO. 2.
7
/7
lZ/
17
fl/
v x 10 -2, crn -~
Flo. 2 FIG. 1 IR spectra of b/s-tri-n-butylstannyl ester of fumaric (1), maleic (2) and succinic (3) acids. Suspensions in vaseline oil. IR spectra of the b/s-tri-n-butylstannyi ester of maleic acid. Temperature 293 (1), 403 (2), 473 K (3). (4) same as (3) after cooling to 293 K.
Four-coordination tin in compound IX is characterized by the band 1550 cm-t, five-coordination tin by 1630 cm -1 and in compound X there is only five-coordination tin (1620 cm -1) since the band at 1550 cm -1 is absent. In the spectrum of monomer I there are no absorption bands in the region 1660-1620 cm -1 indicating the absence of coordination in this compound. Its spectrum is similar to that of the organotin derivative of succinic acid for which intra-molecular coordination cannot be realized. Absence of isomerization also stems from the results of derivatographic investigations (Fig. 3). On heating the monomer II to the temperature of thermal degradation ( ~ 473 K) in the DTA curve after the melting peak (322 K) two exo-effects are present, oxidation (520-530 K) and change in the conformation II by the scheme (1) (473-500 K). This exo-effect confirms the presence in the monomer II of intramolecular coordinations stabilizing the conformers IX and X. Intermolecular coordination for them is thermodynamically disadvantageous since it leads to more open, unfolded conformations. Thus, monomer II is stable to thermal isomerization which contradicts the statement of the authors of references [1, 9] on the ease of its isomerization to the monomer I already occurring at room temperature. It may from all this be assumed that on heating the reaction mixture of the monomers I-styrene and II-styrene to 333 and 353 K thermal isomerization of compound II to monomer I does not occur which, however, gives no grounds for asserting that isomerization will not occur on initiation of polymerization via the free-radical mechanism. To elucidate isomerization in the course of polymerization the copolymers I-styrene and II-styrene were subjected to chemical conversions by the schemes (2) and (3) for the compounds V and VI, respectively o __Cj --COOSnRa HCl --COOH (2) \0 --COOSnRa --COOH --H,O __C/ %0
Synthesis and microstructure of organotin polymers
RsSnOOC--~
.rrcl~ HOOC--
I--COOSnRs
1077
> --O--C[ - --COOH
-/t,o
0
(3)
--C--O-
Il 0 According to these schemes the absence of isomerization of II on copolymerization with styrene must give an isotactic configuration of the unit which after hydrolysis and thermal dehydration will give the elementary units of the cyclic anhydride [Vc=o = 1865 (sym) and 1785 (asym) cm -1 [10]]. If isomerization occurs there must form the syndiotactic configuration of the unit which on dehydration will lead to the formation of acyclic anhydride structures [Vc=o--1787 (sym) and 1750 (asym) cm -1 [10]]. Figure 4 presents the IR spectra of films of hydrolysed organotin copolymers recorded at different temperatures. It will be seen that in the film of the hydrolysed polymer V on heating, the band at 1730cm -1 (Vc=o) of the carboxyl group disappeared and two bands appeared at 1860 and 1785 cm -1 indicating the formation of cyclic anhydride structures. In the film of the hydrolysed polymer VI heated to 523 K bands appeared at 1785 and 1750 cm -1. The position of the bands and their intensity ratio point to the formation of acyclic anhydride structures [10]. +IT
'"--, _,/" III
-~-
(a) ¢785
1785
~) t~
~ l
I II
,.t73 473
Fio. 3
I
l
673 773 7';,/<
'27
1785 3
FxG. 4
FIO. 3. Derivatogramsof bis-tri-n-butylstannyl ester of fumaric(1) and maleic (2) acids. Weighedbatch 98 mg, sensitivity100 mg, heating rate 10 degrees/rain. The sensitivityof the DTA and DTG methods is 1/10. Speed of recording2 ram/rain. Referencealuminiumoxide; mediumair. Fio. 4. Changesin the bandsof the IR spectraof filmsof the copolymersV (a) and VI (b) firstsubjectedto hydrolysison their heating.Temperature273 (1), 303 (2), 483 (3) and 523 K (4). Analysis of the spectra of the hydrolysed polymers V subjected to dehydration shows that during copolymerization of the monomer II with styrene its partial isomerization nevertheless occurs. Quantitative determination of the carboxyl groups (1727 cm -1) not entering into the dehydration reaction and not leading to the formation of the anhydride amounts to 10-15%. Many authors have noticed that the interaction of the styrene-maleic anhydride copolymer with bases, in particular, with tri-n-butyltin oxide, is accompanied by the appearance of an intense purple colour of the reaction mass [5, 11-13], such coloration disappearing on acidification of the medium. Therefore, doubt has been cast on the correctness of the interpretation of the microstructure of the organotin derivatives of maleic anhydride copolymers.
1078
V . A . ZuBov et al.
In the films of HCl-hydrolysed copolymer VII on heating, both units of maleic anhydride (1860 and 1785 cm -1) and acyclic anhydride structures 1785 and 1750 cm -1) were detected. The number of maleic anhydride units tentatively calculated from the intensity ratio of these bands, i.e. isotactic diads in the polymer VII, was - 1 0 times less than for the fumaric acid units, i.e. syndiotactic diads. In accord with reference [14, p. 551] the appearance of purple coloration of the solutions with absorption maximum at 560 nm may point to the formation of carbanions capable of changing as a result of their s p 2 state the configuration of the units, i.e. promoting change in the microtacticity of the polymers with C - - H acid centres H--C--COOSnRs +B:
-C--C00SnRs
H--/--COOSnRsC- B d
H - - CI - - C O O S n R s
q-Brt
RsSnOOC--C-
>
I-I--C--COOSnRa I
'
XI RsSnOOC--C--H
>
I
H--C--COOSnRs
+B:
(4)
XII
Modelling of the structures XI and XII in the copolymer chains taking into account intramolecular coordinations with the aid of Stewart-Brigleb ball-rod models confirms the possibility of change in microtacitity according to the scheme (4). Figures 5 and 6 give the derivatograms and IR spectra of the copolymers VII and VIII. As may be seen from the former in the region 473--500 K exoeffects are observed interpreted as intramolecular regroupings similar to the conversion of compound IX to the structure X by the scheme (1). As follows from the derivatograms the newly formed structures X are unstable and with further rise in temperature are destroyed with the formation of maleic anhydride units (Fig. 6, absorption at 1785 and 1860 cm-1). According to 13C NMR the content of the isotactic diads in the polymer VIII is 4-8% [6] and according to the results of the derivatographic investigations a value />4.7% is obtained practically matching this interval. The lower temperatures of the breakdown of the isotactic diads in the polymer VIII (443--473 K) as compared with the diads in the copolymer VII (483-503 K) may be explained by the presence in
5
3
3 ~
I
i
I
473
F1o. 5 Flc. 5.
I
673
I
"/':,K
2
l
i
i
;'8
16
~
v X 10 -2, c m -7
Flo. 6
Derivatograms of the polymers VIII (1, 2) and VII (3, 4): 1, 3, DTG; 2, 4, DTA. Sensitivity of the DTA method 1/3. Heating rate 5 degrees/min. Reference aluminium oxide; medium air. Fic. 6. IR spectra of polymers VII (1), VII at 423 K after 15 rain (2); VII at 473 K after 15 rain (3) and VIII (4) and VIII at 463 + 10 K after 15 min (5).
Synthesis and microstructure of organotin polymers
1079
the diads of VIII of methyl groups possessing a +I-effect and, thereby, lessening the polarity of the linkage of the polyanions with the tin cations which makes the linkage with the polymer chain less stable than in the copolymer VII.
Translated by A. Cl~ozv
REFERENCES 1. D. A. KOCHKIN, Obrastaniye i biokorroziya v vodnoi srede. Biologicheskiye povrezhdeniya. (Fouling and Biocorrosion in an Aquatic Medium. Biological Damage) p. 164, Moscow, 1981. 2. H. IMAZAKI, Y. KITANO, T. KITAO, S. MURAKANI and H. DOI, Patent 381275 Sweden. RZhKhim 4T638, 1977. 3. V. F. MISCHENKO and V. A. ZUBOV, Vysokomol. soyed. B24: 184, 1982 (not translated in Polymer Sci.
U.S.S.R.). 4. Z. M. RZAYEV, Zh. obshch, khim. 39: 544, 1969. 5. V. F. MISHCHENKO and V. A. ZUBOV, Vysokomol. soyed. A25: 2061, 1983 (translated in Polymer Sci. U.S.S.R. A25: 10, 2389, 1983). 6. B. B. DAMBATTA and J. R. EBDON, Brit, Polymer J. 16: 69, 1984. 7. S. Ya. KHORSHEV, A. I. YEGOROCHKIN and Ye. I. SEVAST'YANOVA, Khimiya elementoorganicheskikh soyedinenii (Chemistry of Elemento-organic Compounds) p. 3, Gorkii, 1980. 8. S. DIETZELS, K. JURKSCHAT, A. TZSCHACK and A. ZSCHUNKE, Z. anorgan, und allgem. Chem. 537: 163, 1986. 9. D. A. KOCHKIN, O. K. BOTCHENKO and G.A. KURAKOV, Stroyeniye veshchestva i fizikokhimicheskii analiz (Structure of Matter and Physico-chemical Analysis) p. 102, Kalinin, 1973. 10. K. NAKANISI, Infrakrasnye spektry i stroyeniye organicheskikh soyedinenii (Infra-Red Spectra and Structure of Organic Compounds) p. 216, Moscow, 1965. 11. N. K. BARAMBOIM and R. G. FOMINA, Trud. Inst. legkoi prom-sti No. 33, 126, 1967. 12. B. L. MOLDEVSKII and Yu. D. KERNOS, Maleinovyi angidrid i maleinovaya kislota (Maleic Anhydride and Maleic Acid) p. 88, Leningrad, 1976. 13. Gy. HARDY, G. KOVACS, H. BOUDEVSKA and V. NEITCHEV, Tez. kr. soobshch. Mezhdunar. simp. po makromolekulyarnoi khimii (Summaries of Brief Communications. International Symposium on Macromolecular Chemistry) Vol. 4, Tashkent, 1978. 14. Obshchaya organicheskaya khimiya (General Organic Chemistry) Vol. 1, p. 736, Moscow, 1981.