DEHYDROHOMOPOLYMERIZATION AND DEHYDROCOPOLYMERIZATION OF NEW ALKYLSILANES - SYNTHESIS OF POLY(3-ARYL-1-SILABUTANES)

Abstract

3-Aryl-1-silabutanes such as 3-phenyl-1-silabutane (1), 3-tolyl-1-silabutane (2), 3-(2,5-dimethylphenyl)-1-silabutane (3), 3-chlorophenyl-1-silabutane (4), 3-(chloro-p-tolyl)-1-silabutane (5), 3-(phenoxyphenyl)-1-silabutane (6), 3-naphthyl-1-silabutane (7), and bis(1-sila-3-butyl)benzene (8) were prepared in 62-98% yields by reduction of the corresponding 3-aryl-1,1-dichloro-1-silabutanes with LiAlH4. The dehydrohomopolymerization and dehydrocopolymerization of the monomer silanes were carried out with the Cp(2)MCl(2)/Red-Al (M = Ti, Hf) combined catalyst system. The molecular weight of the polymers produced ranged from 600 to 1300 (vs polystyrene) with degree of polymerization (DP) equal to 3-16 and with polydispersity index (PDI) equal to 1.1-3.8. A set of the monomer silanes dehydrocoupled to produce a copolymer. The polymerization of bis(silabutyl)benzene (8) seemed to initially produce a low molecular weight of polymer, which then underwent an extensive cross-linking reaction of backbone Si-H bonds, leading to insoluble polymer.