dihalide e g of the formula r 2 c o x in which r 2 and x have the aforestated meanings can then be considered to react to form the product blocked mercaptosilane and a metal halide byproduct in accordance with the reaction useful polysulfane containing organosilicon compounds include for example bis triethoxysilyl propyl polysulfane bis methyldiethoxysilyl propyl polysulfane bis triethoxysilyl isobutyl polysulfane bis methyldiethoxysilyl isobutyl polysulfane bis trimethoxysilyl propyl polysulfane bis methyldimethoxysilyl propyl polysulfane bis trimethoxysilyl isobutyl polysulfane and bis methyldimethoxysilyl isobutyl polysulfane the polysulfane containing organosilicon compound is reacted with an alkali metal alkaline earth metal or a strong base derived from an alkali metal or alkaline earth metal useful alkali metals alkaline earth metals and basic metal derivatives include for example lithium sodium potassium magnesium calcium lithium hydride sodium hydride potassium hydride magnesium hydride calcium hydride sodium methoxide sodium ethoxide potassium methoxide potassium ethoxide and mixtures thereof the resulting polysulfane containing organosilicon compound metal salt is combined with an acyl halide or carbonyl dihalide e g of the general formula r 2 c o x supra in which r 2 is halogen or alkyl alkenyl aryl alkaryl or aralkyl of up to about 18 carbon atoms and x is halogen to produce a blocked mercaptosilane useful acyl halides include acetyl chloride propanoyl chloride butanoyl chloride pentanoyl chloride hexanoyl chloride heptanoyl chloride octanoyl chloride 2 ethylhexanoyl chloride lauroyl chloride oleoyl chloride octyl chloroformate adipoyl chloride phenylacetyl chloride benzoyl chloride terephthaloyl chloride and phenyl chloroformate useful carbonyl dihalides include carbonyl dichloride phosgene diphosgene triphosgene thiophosgene and oxalyl chloride the blocked mercaptosilane product obtained by the.