CYCLIC 7-MEMBERED VINYL ACETALS - INVESTIGATION ON SYNTHESIS AND POLYMERIZATION

Synthesis of the 2-phenyl-substituted 4-methylene-1,3-dioxepanes 3a an d 3b in two steps and their polymerization are described. Photoinitiat ed cationic polymerization under ambient conditions and radical polyme rization with AIBN or DBPO at elevated temperature in bulk lead to qua ntitative ring-opening and give high-molecular weight poly(alkylene-et her-ketone)s. The detection of aldehyde after purification indicates t hat 3a and 3b polymerize with the elimination of aldehyde. A volume sh rinkage of about 3% is found (after purification).