Studies in the Chemistry of Carbazole Derivatives. Polymerization of 3-Chloro-9-vinylcarbazole
Abstract Generated abstract
The study examines the radical polymerization of 3-chloro-9-vinylcarbazole, a substituted 9-vinylcarbazole of interest for heat-resistant dielectric and electrophotographic materials. Polymerization was carried out in bulk, solution, and suspension using benzoyl peroxide or azobisisobutyric acid dinitrile as initiators, with conversion, yield, and viscosity measured under varied temperatures, initiator concentrations, reaction times, and media. The results show that the monomer has limited thermal polymerization in the absence of initiator, while small initiator additions markedly increase conversion, with solution behavior consistent with radical polymerization trends. Suspension polymerization gave the highest molecular weight products, and practical conditions were identified for preparing poly-3-chloro-9-vinylcarbazole by the three methods.
Full Text
Studies in the Chemistry of Carbazole Derivatives
Polymerization of 3-Chloro-9-vinylcarbazole
V. M. Sutyagin, V. P. Lopatinskii, Yu. P. Shekhirev
(Presented by the scientific-methodological seminar
of the Faculty of Chemical Technology)
Poly-9-vinylcarbazole is used for obtaining heat-resistant dielectrics [1], and in recent years also for the preparation of photosensitive electrophotographic layers [2]. At present, some 9-vinylcarbazoles substituted in the benzene rings are known [3—6]; however, the methods for their preparation, their polymerization, and the properties of the resulting polymers have been little studied. This communication presents the results of studies on the polymerization of 3-chloro-9-vinylcarbazole (3Ch9VC).
Experimental Part
3-Chloro-9-VC was obtained by us according to the procedure of [6]; it had m.p. 68—69°C and an unsaturated-compound content of 99.8—99.9% [7, 8].
Polymerization of 3Ch9VC in bulk
10 g of monomer and 0.1 g of Dinis are thoroughly mixed, charged into an ampoule, purged with nitrogen, sealed, and kept in a thermostat at 100°C for 8 hours; then the mixture is cooled, the polymer formed is dissolved in dichloroethane, precipitated with an equal volume of methanol (ethanol), filtered off, and dried. Yield 9.1 g, 91% of the monomer taken.
Polymerization of 3Ch9VC in solution
Into a two-necked flask equipped with a stirrer and reflux condenser are charged 5 g of monomer and 25 ml of toluene (or normal decane); the mixture is heated to 100°C, 0.025 g of Dinis is added, and it is kept for 9 hours. The polymer is precipitated with an equal volume of methanol (ethanol), filtered off, and dried. Yield 4 g, 80% of the monomer taken.
If the reaction is carried out in n-decane, the polymer precipitates; it is filtered off, washed with cold solvent, and dried. Yield 4.5 g, 90% of the monomer taken.
Polymerization of 3Ch9VC in suspension
Into a two-necked flask equipped with a stirrer and reflux condenser are placed a 4—6% aqueous starch solution and 15 g of monomer; the mixture is heated to 100°C, 0.15 g of Dinis is introduced, and it is kept for 8 hours. The ratio of the aqueous and monomer phases is 20 : 1. The obtained polymer granules are filtered off, washed with hot distilled water, and dried—
washed. Then it is dissolved in dichloroethane and precipitated with an equal volume of ethanol, filtered off and dried. Yield 14.25 g, 95% of the monomer taken.
Discussion of Results
Table 1 presents data on the polymerization of 3C9VC in bulk, in solution, and in suspension in the presence of benzoyl peroxide (BP) and azobisisobutyric acid dinitrile (diniz). The conversion of 3C9VC was determined from the amount of free monomer by the mercury acetate addition method [7, 8].
Table 1
Polymerization of 3-chloro-9-vinylcarbazole
| Amount of initiator, % of 3C9VC | Polymerization conditions: reaction temperature, °C | Polymerization conditions: duration, h | Conversion, % | Polymer yield, % | Viscosity, ml/g | Viscosity, $\eta_{\mathrm{ud}}^{*}$ |
|---|---|---|---|---|---|---|
| — | 100 | 8 | 49.42 | 36.5 | 0.13 | |
| — | 100 | 12 | 51.67 | 39.5 | 0.13 | |
| BP | ||||||
| 1.0 | 80 | 8 | 88.25 | 85.8 | 0.39 | |
| 1.0 | 100 | 8 | 89.8 | 87.9 | 0.36 | |
| 0.1 | 100 | 2 | 72.45 | 66.0 | 0.38 | |
| diniz | ||||||
| 0.1 | 100 | 8 | 95.0 | 91.0 | 39.5 | |
| 1.0 | 80 | 4 | 87.0 | 85.0 | 32.0 | |
| 1.0 | 100 | 10 | 94.0 | 90.0 | 30.0 | |
| 0.1 | 120 | 2 | 91.0 | 83.0 | 31.5 | |
| 0.5 | 80 | 4 | 85.2 | 80.0 | 33.0 | |
| 1.0 | 100 | 2 | 90.3 | 85.5 | 30.0 | |
| in solution | in solution | in solution | in solution | in solution | in solution | in solution |
| 0.2 | 100 | 9.0 | 61.0 | 55.0 | 9.0 | |
| 0.4 | 80 | 9 | 21.5 | 20.0 | 8.0 | |
| 0.1 | 100 | 9 | 76.5 | 73.0 | 12.0 | |
| 0.8 | 100 | 9 | 90.0 | 86.0 | 10.0 | |
| 0.1 | 80 | 9 | 9.1 | 3.0 | 16.0 | |
| in suspension | in suspension | in suspension | in suspension | in suspension | in suspension | in suspension |
| 0.1 | 100 | 2 | 78.0 | 75.0 | 220.0 | |
| 0.1 | 100 | 8 | 80.5 | 79.0 | 225.0 | |
| 0.5 | 100 | 2 | 90.15 | 88.5 | 155.0 | |
| 0.5 | 80 | 2 | 65.0 | 58.9 | 185.0 | |
| 1.0 | 100 | 2 | 91.3 | 90.0 | 145.0 |
Note: —relative viscosity of 0.1 g of polymer in 10 ml of benzene at 20°C.
The intrinsic viscosity was determined in dichloroethane solution at 20°C in an Ubbelohde viscometer.
As can be seen from Table 1, 3C9VC has little tendency toward thermal polymerization in the absence of initiators. The addition of even small amounts (0.1%) of initiators increases the rate of polymerization. In all the cases studied, a decrease in the rate of the process is observed when a polymerization depth of 88–96% is reached. As the reaction proceeds, the intrinsic viscosity remains constant.
In the polymerization of 3C9VC in solution, the conversion increases with increasing reaction temperature, with an increase in the amount of initiator and in the concentration of monomer in the system, which is in good agreement with the theory of radical polymerization.
In the polymerization of 3-chloro-9-vinylcarbazole in suspension, the conversion increases only slightly with time; at 80°C the process proceeds more slowly. In the presence of 0.1–1.0% initiator, the viscosity of the polymer decreases markedly as the initiator content is increased.
It has been observed that polymerization of 3-chloro-9-vinylcarbazole in suspension leads to the formation of the products with the highest molecular weight.
Conclusions
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The influence of temperature, the nature and amount of initiator, as well as certain other factors on the polymerization of 3-chloro-9-vinylcarbazole in bulk, in solution, and in suspension has been studied.
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The optimal polymerization conditions for each case have been established, and procedures have been developed for the synthesis of poly-3-chloro-9-vinylcarbazole in bulk, in solution, and in suspension.
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