Trichlorosilane and methyldichlorosilane add to the double bond of certain alkenes in the presence of y-rays a'j initiator. These compounds include octene-1, isobutylene, butene-2, 2- methyl-2-butene, cyclopentene, cyclohexene, l-methylcyclohexene, allyl chloride, allyl acetate, allyl cyanide, cis-1, 2-dichloroethylene, 3, 3, 4, 4, 4-pentafluoro-l-butene, 2-methyl- 3, 3,-4, 4, 4-pentafluoro-l-butene, 3, 3, 4, 4, 5, 5, 5-heptafluoro-l-pentene and 2-methyl-3, 3 ...