2,4,6-三甲氧基脱氧安息香的合成新方法

A new method for synthesis of 2,4,6-trimethoxydeoxybenzoin

以1,3,5-三甲氧基苯替代间苯三酚为原料和苯乙腈反应,用甲苯替代不易回收且安全性较差的乙醚为溶剂,通过Hoesch反应制备得到2,4,6-三甲氧基脱氧安息香,产品经HNMR和MS定性.因醚键的保护作用降低了羟基的反应活性,抑制了副反应,使得方法改进后,Hoesch反应的单步收率提高到81.3%.考察了原料配比、反应时间及ZnCl2用量对反应的影响,得到了较佳的反应条件为1,3,5-三甲氧基苯与苯乙腈的摩尔配比为1.2∶1,反应时间为28 h,ZnCl2与苯乙腈的摩尔配比为0.3∶1.

2,4,6-trimethoxydeoxybenzoin was prepared through Houben-Hoesch reaction from 1, 3,5-trimethoxybenzene and 2-phenylacetonitrile. Toluene was used as solvent instead of highly volatile and particularly hazardous diethyl ether. The product was characterized by 1 HNMR and MS. Because of the protective effect of ether bond, the reactivity of hydroxy group was reduced and the side reactions were inhibited. With this improved synthetic method, the yield of Houben- Hoesch reaction reached up to 81.3%. In this work, the effects of the ratio of raw materials （1, 3,5-trimethoxybenzene ： 2-phenylacetonitrile）, reaction time and the amount of zinc chloride on the yield were investigated. Optimization of reaction conditions were as follows： the ratio of raw materials （1,3,5-trimethoxybenzene ： 2-phenylacetonitrile） was 1.2 ： 1, reaction time 28 h and the ratio of zinc chloride and 2-phenylacetonitrile 0.3： 1.