Stereospecific Radical Polymerization of α-(Alkoxymethyl)acrylates Controlled by a Catalytic Amount of Zinc Halides

The stereospecific radical polymerization of α-(alkoxymethyl)acrylates benzyl α-(methoxymethyl)acrylate, benzyl α-(ethoxymethyl)acrylate, and ethyl α-(ethoxymethyl)acrylate in the presence of a catalytic amount of zinc halides (ZnCl 2 and ZnBr 2 ) was attained, and the obtained polymers had very different tacticities, rich in syndiotacticity (up to r = 0.71), from that prepared in the absence of a zinc salt (atactic). In contrast, no change was observed in the stereoregularity of the polymethacrylates radically obtained in the presence of ZnBr 2 as an additive. The coordination of zinc salts to polar α-substituents on the ω-end of the propagating polymer and the monomer must play an important part in this system.