离子液体催化CO2与环氧化物合成环状碳酸酯

综述了离子液体催化CO2与环氧化物的环加成反应制备环状碳酸酯的研究进展。目前报道的离子液体主要包括咪唑盐、季铵盐、季鏻盐等。对比了传统离子液体与功能化离子液体对CO2环加成反应的催化活性、选择性以及催化作用机制。与传统的离子液体相比,功能化离子液体的羟基或羧基等官能团与卤素离子等Lewis碱之间存在协同效应,使得其对CO2与环氧化物的环加成反应具有更好的催化活性;将功能化离子液体固载于无机材料(SiO2,SBA-15,MCM-41等)或聚合物所得的多相催化剂不仅保持了官能团与阴离子之间的协同效应,而且载体与离子液体活性组分之间也显示出协同效应,使得该类催化剂具有很好的催化活性,稳定性好,可以多次重复使用,具有较好的工业化前景,是值得深入研发的一类催化材料。此外,离子液体对于手性环状碳酸酯的合成也具有较好的催化活性和立体选择性。

Synthesis of Cyclic Carbonates from CO2 and Epoxides Catalyzed by Ionic Liquids

This review summarizes the research progress on the use of ionic liquids(ILs) as catalysts for the cycloaddition of CO2 with epoxides to prepare cyclic carbonates.The reported ILs for this reaction include imidazole salt,quaternary ammonium salt,quaternary phosphonium salt,and so on.Systematical comparison has been made between the conventional ILs and functional ILs in the terms of their catalytic performances and reaction mechanisms.Generally,the conventional ILs show poor catalytic efficiency towards this coupling reaction,thus co-catalysts are usually needed to improve their catalytic activity.Compared with conventional ILs,functionalized ILs show much better catalytic performance due to the synergistic effect between hydroxyl or carboxylic acid group and Lewis base such as halide anions.As to the supported ILs catalysts,inorganic material SiO2 is the most common support for immobilizing or supporting ILs catalysts.In the recent years,mesoporous materials such as SBA-15 and MCM-41 whose surfaces are of hydroxyl groups can also be used to immobilize ILs.Besides inorganic materials,polymers are another type of important supports,and the polymers-supported ILs are more stable than ILs on inorganic supports.Moreover,there is synergistic effect between the active components and supports of the immobilized functional ILs,resulting in better catalytic performance.It is emphasized that supported ILs catalysts have good potential applications in industry since they show good catalytic activity,selectivity and recyclability.What’s more,ILs can also be used as catalysts for the preparation of chiral cyclic carbonates with good yield and enantioselectivity.