[摘要]:The radical reactions of linear and cyclic dimethylsiloxanes were studied. It was found that methyl radicals decayed in linear and branched polymethylsiloxanes and dimethylsilanediol at 77 K as a result of radical center transfer. It was established that distonic radical cations were formed and the siloxane ring was opened in cyclic siloxanes D-3 and D-4 upon irradiation in the bulk at 77 K.