碱性离子液体1-乙基-3-甲基咪唑磷酸二乙酯盐在Knoevenagel反应中的应用

Application of Basic Ionic Liquid 1-Ethyl-3-methylimidazolium Diethylphosphatete Knoevenagel Reactions

考察了碱性离子液体1-乙基-3-甲基咪唑磷酸二乙酯盐{[Em im]＋[（EtO）2（PO）O]-}催化一系列醛与活性亚甲基类化合物的Knoevenagel反应,比较了该离子液体在有溶剂存在及无溶剂条件下的催化性能。结果表明,该离子液体在乙醇作溶剂条件下对芳香醛的反应具有较高的催化活性,采用摩尔分数为20%的离子液体来催化该反应,于室温反应即可顺利完成,产率达73.2%-97%,生成相应的取代烯烃化合物。在无溶剂条件下采取机械研磨的方法进行反应,该离子液体表现出更高的催化活性,采用摩尔分数为10%的离子液体进行反应,在1-10 m in即可使产率达90%以上,所得产物均为E式构型。而且在无溶剂条件下,不仅可催化芳香醛的反应,亦可催化脂肪醛的反应。所用离子液体可重复使用,第5次使用时产率仍能达到85.9%。

Basic ionic liquid 1-ethyl-3-methylimidazolium diethylphosphate {＋[（EtO）2（PO）O]-} was introduced as the catalyst for the Knoevenagel reaction of aldehydes with active methylene compounds.The catalytic activity of the ionic liquid was investigated with ethanol as the solvent and in the case without the presence of the solvent.The results show that the condensations of aromatic aldehydes proceed efficiently at room temperature with ethanol as the solvent to obtain the E-isomers in high yield（73.2%～97%） in the presence of 20% ionic liquid.At the solvent-free condition,the Knoevenagel reactions of aromatic aldehydes proceed smoothly（1～10 min） in the presence of 10% ionic liquid by mechanochemical grind.Comparing to the reations with ethanol as the solvent,these reactions can be carried out faster.Another feature of the methodology at the solvent-free condition is the condensation of aliphatic aldehydes with active methylene compounds,which is not easy to achieve by conventional reagents.The ionic liquid could be recycled five times and a yield of 85.9% of the last run was obtained.