Initiation and propagation reactions in the copolymerization of epoxide with carbon dioxide by catalysts based on diethylzinc and polyhydric phenol

Propylene oxide and cyclohexene oxide were copolymerized with carbon dioxide in the presence of catalysts such as diethylzinc with phenol or 1-phenoxy-2-propanol and/or a polyhydric phenol (polyhydroxybenzene derivatives such as 4-tert-butylcatechol, pyrogallol): The corresponding copolymers with predominant carbonate linkages and the respective cyclic alkylene carbonates as by-products were obtained in the presence of catalysts derived from diethylzinc and polyhydric phenol. Cyclic alkylene carbonates but no polymeric products were formed in the presence of catalysts derived from diethylzinc and monoprotic compound. The copolymers were analysed by means of 1H- and 13C nuclear magnetic resonance (NMR) spectroscopy in terms of chain microstructure and end groups. Alkaline hydrolysis of the cyclohexene oxide/carbon dioxide copolymer was performed and the trans-structure of the obtained cyclohexane-1,2-diol was determined. Mechanisms for the initiation and propagation reactions are proposed and discussed.