Several novel organotin copolymers derived from poly-3 and poly-4-(2-di-n- butylchlorostannyl) ethylstyrene-co-divinylbenzene-co-styrene have been prepared. Copolymer-bound organotin oxides, as a mixture of stannol and distannoxane, have been shown to catalyze the lactonization of hydroxycarboxylic acids.
