壳聚糖固载碱性离子液体催化Knoevenagel缩合反应

Knoevenagel Condensation Catalyzed by a Basic Ionic Liquid Catalyst Immobilized on Chitosan

通过壳聚糖与1-乙烯基-3-丁基氯化咪唑([VBIm]Cl)的自由基加成反应以及随后与KOH溶液的阴离子交换反应,制备了壳聚糖固载碱性离子液体催化剂(CS-NH-[EBIm]OH)。考察了该催化剂在苯甲醛与丙二腈的Knoevenagel缩合反应中的催化性能。结果表明:CS-NH-[EBIm]OH是催化Knoevenagel反应的高效多相催化剂,所得缩合产物(苯亚甲基丙二腈)的收率和选择性分别高达99.1%和100%。每次使用后的催化剂经简单处理后可以再循环使用4次而产物产率无明显下降。此外还发现CS-NH-[EBIm]OH对各种醛和丙二腈的Knoevenagel缩合反应表现出较高的催化活性。

A basic ionic liquid-immobilized chitosan catalyst(CS-NH-[EBIm]OH)was prepared by the radical addition reaction of chitosan with 1-vinyl-3-butylimidazolium chloride([VBIm]Cl),and a subsequent anion-exchange reaction with KOH solution.The catalytic performance of the obtained catalyst was investigated in Knoevenagel condensation of benzaldehyde and malononitrile.The results showed that CS-NH-[EBIm]OH was an effective heterogeneous catalyst and the yield and selectivity of the obtained condensation product(benzylidene malononitrile)were as high as 99.1%and 100%respectively.The catalyst after each used could be reused 5 times after simple treatment without a significant decrease in product yield.Moreover,it was found by changing the reaction substrate aldehyde that CS-NH-[EBIm]OH exhibited high catalytic activity for Knoevenagel condensations of a wide range of aldehydes and malononitrile.