碱性聚合离子液体用于Claisen-Schmidt缩合反应的研究

Claisen-Schmidt Condensation Catalyzed by Alkaline Poly(ionic liquid)

制备了聚咪唑-环氧氯丙烷离子液体,通过碱交换合成了碱性聚合离子液体,用红外、核磁、凝胶色谱法、电位滴定等手段进行表征,结果表明该离子液体催化剂聚合度较高,相对分子质量分布较窄,其OH-交换率大于95%.该离子液体对芳香醛与酮类的Claisen-Schmidt缩合反应有着良好的催化性能,苯甲醛与丙酮在25℃下,醛酮比为1∶4,在2.5 mol/L的醛溶液中,添加质量分数为2%的催化剂反应仅10 h即可达到99%的产率,在超声条件下反应4 h即可达到90%的收率,且该碱性离子液体经5次回收重复利用,其产率保持在90%以上.该催化剂在低添加量下具有较高的催化活性和较好的重复使用性能.

Poly（iminazole-epichlorohydri） ionic liquid was synthesized and basic poly（ionic liquid） was prepared by alkali exchange and was characterized by FT-IR, NMR, GFC, potentiometric titration methods. It turns out that the poly（ionic liquid） has perfect degree of polymerization and very concentrated relative molecular weight distribution, and the exchange ratio of hydroxyl ion can be over 95%. Claisen-Schmidt condensation reaction was efficiently catalyzed by the poly（ionic liquid）. For example, taking the condesation of aldehyde and ketone （aldehyde ： ketone= 1 ： 4） in 2.5 rnol/L aldehyde solution with 2% （weight） catalyst at 25 ℃ for 10 h, the yield can reached 99%. Ultrasonic waves can enhance the reaction with a yield of 90% in 4 h. After recycling use of the catalyst for 5 times, the yield still did not less than 90%. The catalytic activity of the catalyst is higher in low addition, and catalyst could be reused well.