苯并咪唑盐催化的水相安息香缩合反应

Benzoin Reaction in Aqueous Medium Catalyzed by Benzimidazolium Salts

合成了几种不同链长的烷基N-甲基苯并咪唑溴盐,以水为溶剂,催化苯甲醛进行安息香缩合,效果良好。研究了催化剂结构、碱的类型、催化剂用量、反应时间和反应温度等因素对反应的影响,获得了最优条件。实验结果表明,2 mmol苯甲醛在2 mL水中,0.05 mmol(摩尔分数为2.5%)1-甲基3-丁基苯并咪唑盐和1 mL质量分数为1.6%NaOH水溶液催化下,于40℃下反应4 h,收率可达84%。该方法的显著优点为反应条件温和、后处理简单,以环境友好的水作为溶剂,催化剂易得且可多次循环利用。

Some benzimidazolium salts have been synthesized and used as catalyst in benzoin reaction with good result.The effects of catalyst structure,base type,catalyst ammount,reaction time and temperature on the reaction were studied,and the optimal conditions were obtained.Experimental results showed that when 2 mmol benzaldehyde was catalyzed by 0.05 mol(mole fraction:2.5%)of 1-methyl-3-butylbenzimidazoliumbromide and 1 mL mass fraction of 1.6%NaOH aqueous solution at 40℃for 4 h in 2 mL of water,the yield of benzoin was 84%.The remarkable advantages of this methodology include mild reaction conditions,easy work-up and environmentally friendly water as solvent,the catalysts are easy to synthesize and can be recycled many times.