Summary 1.@-Chloroethyltrichlorosilane and 8-chloron-propyltrichlorosilane with aqueous alkali give ethylene and propylene, respectively. The extremely rapid reaction of beta C-Cl bonds with dilute alkali is not a hydrolysis, but a@-elimination, similar in type to the dehydrohalogenation of alkyl halides. It involves tetracovalent silicon instead of a combined hydrogen atom. 2. Reaction of@-chloroethyltrichlorosilane with methylmagnesium ...