Mechanism of Charge-Transfer Polymerization. I. Polymerizations of N-Vinylcarbazole with Some Quinones in a Non-Polar Solvent

The polymerization of N-vinylcarbazole (VCZ) by p-chloranil (p-CA) and a few related quinoid compounds was studied in a non-polar solvent. The rapid charge-transfer polymerization of VCZ ostensibly initiated by p-CA turned out to be mainly a conventional cationic one initiated by a residual amount of 3,5,6-trichloro-2-hydroxy-p-benzoquinone which was retained in p-CA purified by recrystallizations or sublimations. Chromato-graphy over calcium carbonate followed by recrystallizations and fractional sublimations was found to be an efficient purification method. The charge-transfer polymerization was accompanied by the formation of carbazole. The rate of polymerization followed the order: VCZ–p-BA>VCZ–p-CA>VCZ–2,6-dichloroquinone. 2,5-Dichloroquinone did not initiate the polymerization of VCZ under the same conditions. Some cationic species have been proposed in the initiation process of the polymerizations in view of the cationic propagation.