Ring size effect of crown ether on the fixation of carbon dioxide into an oxirane polymer

Several methacrylate derivatives having a crown ether group, the size of which was changed from 12-crown-4 to 16-crown-5, were newly prepared and copolymerized with glycidyl methacrylate under radical conditions. The obtained copolymers (CP1-5) were employed for the fixation of CO2 into the oxirane moieties using lithium salt as a catalyst. The conversion of oxirane to five-membered cyclic carbonate groups by fixation of CO2 was related with the ring size of crown ethers and reflected the association constants for Li+. The most efficient fixation of CO2 in nitromethane solution was observed in the use of CP3, having 14-crown-4 groups, in which oxirane groups were transformed into the corresponding cyclic carbonate groups quantitatively, and further, the reaction proceeded readily even in the solid state.