双位点碱性离子液体对Knoevenagel缩合反应的协同催化作用

Synergistic Effect of an Ionic Liquid Catalyst with Two Kinds of Basic Sites on Knoevenagel Condensation

分别处于阴阳离子中具有两种碱性位点的离子液体催化剂1-(2-哌啶基-乙基)-3-甲基咪唑吗啉乙基磺酸盐([Pemim]-Mes)在Knoevenagel缩合反应中表现出明显的协同促进催化作用.该催化剂在非酸性条件下循环使用10次以后仍保持良好的活性和稳定性,并普遍适用于芳香醛类底物的缩合反应.根据实验结果,提出了紧密结合的碱性阴阳离子对协同催化Kno-evenagel缩合的反应机理.

1-（2-piperidyl-ethyl）-3-methylimidazolium 2-morpholinyl-4-ethane sulfonate （L Pemim J Mes） with two basic groups individually located in cation and anion exhibited synergistically catalytic behavior for Knoeve- nagel condensation. Under non-acidic conditions, [Pemim] Mes proved to be an active, stable, and universal catalyst for Knoevenagel condensation between aromatic aldehydes and active methylene compounds. The catalytic mechanism of Knoevenagel condensation synergistically catalyzed by the basic ion pair existing in [Pemim] Mes was tentatively proposed.