Inquiry into the formation of cyclic carbonates during the (salen)CrX catalyzed CO2/cyclohexene oxide copolymerization process in the presence of ionic initiators

The activation barriers for cyclic carbonate formation from metal-bound polymer chains in isolated (salen)CrX intermediates was reported. 50 mg of (salen)CrCl and 1 equivalent of PPNCl were dissolved in one-to-one mixture of CH 3OH/benzene and the solution was dried under vacuum over a 3 hour period. Then 20 ml of freshly distilled cyclohexene oxide was added, and the solution was cannulated into a stainless steel reactor, which had been dried under vacuum at 80°C for over 6 hours. The copolymer was precipitated from methanol in the presence of HCl. The cyclic carbonate was found to undergo ring-opening polymerization with an increase in reaction temperature. The study revealed that the depolymerization reaction leading initially to cyclic carbonate was demonstrated to be enhanced in the presence of excess anionic cocatalyst, by way of a metal displaced anionic copolymer chain.