Polyvinylchloride stabilisation with organo-tin compounds—Part 1: Mechanism of the reaction of thioglycolate derivatives with allylic chlorine model compounds

Mixtures of the isomers 4-chloro-hex-2-ene and 2-chloro-hex-3-ene of different compositions were prepared in order to study their reaction with organo-tin thioglycolate. Whatever the initial composition of the mixture, the same composition of the isomeric products is obtained. This favours an ionic mechanism in which the rate-determining step is the formation of an allylic carbocation. The substitution reaction with free thioglycolate esters is more rapid than with the tin derivative. Thus, a second possible route for the stabilisation reaction can be proposed.