CATIONIC POLYMERIZATION OF 7-MEMBERED CYCLIC SULFITES - SUBSTITUENT EFFECT ON THE POLYMERIZATION BEHAVIOR

The syntheses and cationic polymerizations of seven-membered cyclic su lfites having phenyl (7PhCS), benzo (7BnCS), and cyclohexane (7CyCS) g roups were examined. 7PhCS and 7CyCS underwent complete elimination of SO2 to afford the corresponding tetrahydrofuran derivatives under the cationic conditions. On the other hand, 7BnCS underwent cationic poly merization in the presence of cationic initiators such as TfOH, TfOMe, SnCl4, TsOMe, and MeI in bulk or chlorobenzene to afford the correspo nding polymer with (M) over bar(n) 950-8700 without desulfoxylation. T he benzo group was operative for polymerization and suppression of des ulfoxylation. The polymerization of 7BnCS did not show equilibrium cha racter. The steric hindrance of the benzene ring might be effective to suppress a back-biting reaction. The volume expansion during the poly merization of 7BnCS was 8.57%. This might be caused by the larger dipo le-dipole interactions between the monomers and smaller ones between t he polymers.