对氨基苯甲醇的超声辐射合成研究

采用对硝基甲苯为原料,经卤代、超声辐射相转移催化水解及超声辐射Pt/C催化转移加氢等3步反应,以67.4%的总收率合成了标题化合物。结果表明:N-溴代丁二酰亚胺为较好的卤代试剂,生成对硝基苄溴的收率为75.4%;以四丁基溴化铵为相转移催化剂,在碱性条件下于70℃时超声辐射0.5 h,对硝基苯甲醇的收率为94.8%;考察了超声辐射Pd/C催化甲酸铵还原对硝基苯甲醇的影响因素,优化了反应工艺:在n(对硝基苯甲醇)∶n(甲酸铵)为1∶4,m(对硝基苯甲醇)∶m(Pd/C)为100∶5,超声功率为150 W,超声温度为50℃,反应时间为15 min的条件下,对氨基苯甲醇的收率为94.3%,Pd/C容易分离回收,可重复使用6次以上。用IR、1HNRM、MS谱及元素分析等测试技术表征了产物的结构。

Synthesis of 4-aminobenzyl alcohol under ultrasound irradiation

An important organic intermediate p-aminobenzyl alcohol is commonly synthesized with overall yield of 67.4% by halogenation,hydrolyzation with phase transfer catalytic method under ultrasonic irradiation and catalytic transfer hydrogenation with Pt/C under ultrasonic irradiation using p-nitrotoluene as raw material.The results show that N-Bromosuccinimide is a good halogention reagent to give p-nitrobenzyl bromide undergoing a radical reaction with p-nitrotoluene with yield of 75.4%;and then converted to p-nitrobenzyl alcohol with yield of 94.8% by basic hydrolyzation with phase transfer catalyst tetrabutyl ammonium bromide under ultrasonic radiation at 70 ℃ for 30 min;thus,several factors affecting the ultrasound reduction of p-nitrobenzyl alcohol were investigated,and the optimum reaction conditions were obtained as follows:the mole ratio of p-nitrobenzyl alcohol to ammonium formate of 1∶4,the mass ratio of p-nitrobenzyl alcohol to Pd/C catalyst of 100∶5,ultrasonic power of 150 W,reaction temperature of 50 ℃ and reaction time of 15 min.Under above reaction conditions,the average yield of p-aminobenzyl alcohol can reach up to 94.3%.The Pd/C catalyst can be easy of recovery for reusing again over 6 times,and the products were confirmed by IR,1HNRM、MS and elemental analysis.