四羰基钴/咪唑离子液体在羰基化合成丙二酸二甲酯反应中的催化性能

采用原位法合成了不同类型的四羰基钴/咪唑离子液体催化剂, 并考察了其在氯乙酸甲酯羰基化反应中的催化性能. 研究了咪唑环上不同支链对催化活性的影响. 结果表明, 1-丁基-3-甲基咪唑羰基钴离子液体[Bmim][Co(Co)₄]不仅催化活性高, 选择性好, 而且对空气和水有较好的稳定性能. 在p_CO=2.0 MPa, 85 ℃, 反应3 h的条件下, [Bmim][Co(Co)₄]催化剂循环使用4次, 氯乙酸甲酯的平均转化率为94.3%, 丙二酸二甲酯的平均选择性和平均产率分别为98.5%和92.9%. 与传统的Na[Co(Co)₄]催化剂相比, [Bmim][Co(Co)₄]催化剂在保证高活性的条件下可以实现羰基钴催化剂的直接循环使用.

Catalytic Properties of Cobalt Tetracarbonyl/Imidazolium Ionic Liquids in the Synthesis of Dimethyl Manolate by Carbonylation

A series of [Co(CO)4]-/imidazolium ionic liquids was synthesized,and their catalytic properties were evaluated in the carbonylation reaction of methyl chloroacetate.The effect of imidazolium with different branched chains on the catalytic properties of [Co(CO)4]-species was investigated.The experimental results show that 1-butyl-3-methylimidazolium cobalt tetracarbonyl([Co(CO)4]) is an efficient and reusable catalyst for the carbonylation of methyl chloroacetate.At reaction conditions of pCO=2 MPa,85 ℃,and t=3 h,the average conversion of methyl chloroacetate was 94.3%,the average selectivity to malonic ester was 98.5% and the average yield of dimethyl malonate was 92.9% for [Co(CO)4] catalyst at four recycles.Compared with the traditional Na[Co(CO)4] catalyst,[Co(CO)4] catalyst exhibited high activity and good reusability,which could be mostly attributed to the good stability for air of the versatile [Co(CO)4]-species at the circumstance of imidazolium ionic liquids.