Polyvinylchloride stabilisation with organotin compounds—Part III: Effect of lewis acidity and co-ordination of organotin chlorides upon their catalytic activity towards dehydrochlorination

The catalysis of the E2 dehydrochlorination of a model compound for the allylic chlorine atoms in PVC involves the co-ordination of this chlorine to the tin atom. It is enhanced by an increase in the Lewis acidity of the tin chloride compound (scaled by Mossbauer spectroscopy), but may be inhibited if other groups, internal or external, are competing for the co-ordination. HCl may be one of these competitors, although, in some cases, it breaks the weakest tin—carbon bonds, giving rise to stronger prodegradant Lewis acids.