THERMAL RING OPENING OF CYCLOPROPANES AS INITIATORS FOR POLYMERIZATION

Abstract

Donor-Acceptor tetramethylenes have been studied by polymerizations. 1,4-Zwitterionic intermediates are indicated when reactive tetramethylenes initiate homopolymerization. Alternately, 1,4-diradical intermediates initiate copolymerization. This basis for studying intermediates has led to an empirical table for predicting the zwitterionic and diradical nature of addition and polymerization reactions of tetramethylenes. Here we attempted to extend this work to trimethalylenes by studying the thermal ring opening of ethyl chrysanthemate, ethyl 1-cyano-2-(4-methoxyphenyl)-cyclopropane-corboxylate, ethyl 1-cyano-2-(2-methoxyphenyl)-cyclopro-panecroboxylate, and diethyl 1,3-dicyano-w,r-di(2-methoxyphenyl)-cyclobutanedicarboxylate. These compounds were found to be thermally stable to 150°C and did not initiate polymerization in styrene, methyl methacrylate, a series of high boiling acrylates, and dimethyl fumarate. Free radicals were trapped in dimethyl fumarate to give oligomers at temperatures above 110°C. Even though the compounds studied did not initiate polymerization at decomposition temperatures of 175°-200°C, dimethyl fumarate may prove useful in these studies in the future.