Cycloaddition of carbon dioxide to epoxides was catalyzed by the binary catalyst systems of phthalocyaninatoaluminium chloride (PcAlCl) and Lewis bases (such as tributylamine, 1 methylimidazole, triphenylphosphine, triethylamine, pyridine and quinoline). The Lewis bases were the excellent promoters, but either component of the binary catalyst systems had low catalytic activity individually. For example, when 0 18 mol of propylene oxide was reacted with 0 36 mol of CO 2 at 140 ℃ for 1 7 h in the presence of 0 18 mmol of PcAlCl and 0 81 mmol of tributylamine, the yield of propylene carbonate was 99 7%; while the yield was 17 4% when used PcAlCl only. Promoting effects of Lewis bases were in the order: 1 methylimidazole>triphenylphosphine>tributylamine>triethylaminepyridinequinoline. Reactivity of the epoxides used was in the order: CH 2Cl>H, CH 3.
