Abstract: Under supercritical carbon dioxide conditions, the reaction of carbon dioxide and epoxides occurred with zinc maleate as the catalyst. Zinc maleate as a sole catalyst showed a low catalytic activity. The coexistence of organic bases, such as DBU, triethylamine(Et3N), imidazole, pyridin-4-ylamine, DMAP or pyridine, could promote this reaction, and the yields of the product were increased obviously. The activity order of organic bases as a function of cocatalyst was DBU>Et₃N>imidazole>4-aminopyridine>DMAP>pyridine. Propylene carbonate could be obtained in 83.4% yield at 110 ℃ under 8 MPa of carbon dioxide pressure for 48 h in the presence of the binary catalyst system of zinc maleate and DBU. A verity of epoxides could also be transformed to the corresponding cyclic carbonates with a high yield in the presence of the binary catalyst system.

Key words: Zinc maleate, Epoxides, Supercritical carbon dioxide, Cyclic carbonate, Synthesis