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利用一步原位反应由大孔聚苯乙烯苄胺树脂和单氰胺合成含有胍基官能团的强碱阴离子交换树脂(PG),通过傅立叶红外、酸碱滴定、元素分析、SEM对胍基树脂进行了表征,同时考察了体系中pH值、投料比、温度对原位反应的影响,实验结果表明,在pH值为2的溶液中,大孔树脂氨基交换量与单氰胺的摩尔比为1∶3时,110℃反应5 h,树脂的强碱交换量达3.54 mmol/g.以胍基强碱树脂为非均相催化剂,催化Knoevenagel缩合反应,探讨了催化剂用量、反应溶剂、反应时间、树脂重复使用等因素对产率的影响,确定了反应的最佳条件.实验结果表明,该树脂具有良好的催化活性,在以乙醇为溶剂,反应时间为5 h,强碱树脂固载胍基含量与反应底物的摩尔比为1∶5时,胍基强碱树脂催化Knoevenagel缩合的反应产率达到83.1%~95.3%,胍基强碱树脂可循环使用,在5次重复实验中,其催化活性基本保持.
The strong base anion exchange resin (PG) containing guanidine functional groups was synthesized from macroporous polystyrene benzylamine resin and cyanamide by one step in situ reaction. The guanidine resin was characterized by Fourier transform infrared spectroscopy, acid-base titration, elemental analysis and SEM The effects of pH value, feed ratio and temperature on the in-situ reaction were investigated. The experimental results showed that the molar ratio of amino exchange capacity of macroporous resin to cyanamide was 1 in the solution with pH value of 2 : 3, reaction time of 110 ℃ was 5 h, the exchange capacity of the resin was 3.54 mmol / g.With guanidinium basic resin as heterogeneous catalyst, the Knoevenagel condensation reaction was catalyzed, the effects of catalyst dosage, reaction solvent, reaction time, Resin reuse and other factors on the yield of the reaction to determine the optimal reaction conditions.The experimental results show that the resin has good catalytic activity in ethanol as the solvent, the reaction time is 5 h, strong base resin immobilized guanidine The molar ratio of the substrate to the substrate was 1: 5, the reaction yield of Knoevenagel condensation catalyzed by guanidinium-base-base resin reached 83.1% -95.3%. The guanidine-based alkali-base resin could be reused. The catalytic activity is basically maintained.