固载化冠醚二苯并-18-冠-6在苯甲酸丁酯合成反应中的相转移催化作用

Phase Transfer Catalytic Activity of Immobilized Dibenzo-18-Crown-6 for Butyl Benzoate Synthesis

在交联聚乙烯醇(CPVA)微球表面固载冠醚二苯并-18-冠-6(DBC),从而制得三相相转移催化剂DBC-CPVA;在此基础上,以苯甲酸钾与溴代正丁烷的酯化反应为模型反应体系,重点研究固体催化剂DBC-CPVA的相转移催化性能,考察主要因素对液-固-液三相相转移催化反应的影响.结果表明,在本研究体系中,水相中的苯甲酸钾与有机相中的溴代正丁烷可顺利地发生酯化反应,这一结果显示出固载于DBC-CPVA表面的DBC与K+离子形成的络合物阳离子,能有效地将苯甲酸根负离子转移至有机相,使酯化反应顺利地进行.有机相的极性越强,酯化反应的速率越快,溴代正丁烷的转化率越高;有机相与水相体积比为1:4时,酯化反应具有最大的速率,溴代正丁烷的转化率可达70%.固体催化剂DBC-CPVA循环使用8次,催化活性保持稳定.

Dibenzo-18-crown-6 （DBC） was immobilized on cross-linked polyvinyl alcohol （CPVA） microspheres to prepare the triphase-transfer catalyst DBC-CPVA.The phase transfer catalytic behavior of DBC-CPVA was mainly studied using the esterification reaction of 1-bromobutane in the organic phase and potassium benzoate in the water phase as a model system.We examined the effects of the main factors on the phase transfer catalytic esterification reaction.The experimental results show that after the benzoic acid in the water phase reacts with KOH to form potassium benzoate,complex cations form between the immobilized DBC and K ＋ ions.The complex cations will effectively carry negative benzoate ions from the water phase into the organic phase and this enables the esterification reaction between benzoate ion and 1-bromobutane to be favorably carried out.Solvent polarity is advantageous to the esterification reaction.When the volume ratio of the organic phase to the water phase is 1：4,a maximum conversion of about 70% for 1-bromobutane is obtained.The catalyst DBC-CPVA has excellent recycle and reuse properties and the catalytic activity remains stable after eight cycles.