超临界二氧化碳中马来酸锌催化合成环状碳酸酯

在超临界二氧化碳中, 利用马来酸锌催化二氧化碳与环氧化物反应合成环状碳酸酯. 单独使用马来酸锌作为催化剂时, 对二氧化碳与环氧丙烷反应的催化活性较低, 而在DBU、DMAP、三乙胺、吡啶、咪唑或4-氨基吡啶等有机碱的存在下, 反应活性较高, 产物的收率得到明显提高. 有机碱作用的强弱顺序为DBU>Et3N>咪唑>4-氨基吡啶>DMAP>吡啶. 在压力为8 MPa, 温度110 ℃, 反应时间48 h条件下, 马来酸锌与DBU组成的二元催化系统可以催化二氧化碳与环氧丙烷反应, 得到83.4%产率的碳酸丙烯酯. 该二元系统也能催化其它环氧化物高产率地转化为相应的环状碳酸酯.

Synthesis of Cyclic Carbonates Catalyzed by Zinc Maleate Under Supercritical Carbon Dioxide Conditions

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.