2-羟基-4,6-二甲氧基脱氧安息香催化合成工艺

Catalytic synthesis process of 2-hydroxy-4,6-dimethoxydeoxybenzoin

以1,3,5-三甲氧基苯为原料,经Houben-Hoesch反应或Friedel-Crafts酰化反应得到2,4,6-三甲氧基脱氧安息香后选择性脱去2位甲基,得到2-羟基-4,6-二甲氧基脱氧安息香目标产品。因甲基的保护作用降低了羟基的反应活性,使Houben-Hoesch反应单步收率提高到81.3%,Friedel-Crafts酰化反应收率达94.5%,脱甲基反应收率达93.8%。考察了催化剂用量、温度等因素的影响,优化选择了各反应的较佳工艺参数。Friedel-Crafts酰基化反应中,催化剂AlCl3与1,3,5-三甲氧基苯的摩尔配比1.1∶1,反应温度25℃(室温);脱甲基反应中,脱甲基试剂与2,4,6-三甲氧基脱氧安息香的摩尔配比1.2∶1,反应温度82℃。产品经1H NMR、MS进行了结构表征。

2-Hydroxy-4,6-dimethoxydeoxybenzoin was synthesized from 1,3,5-trimethoxybenzene,via the Houben-Hoesch reaction or Friedel-Crafts reaction and demethylation of 2,4,6-trimethoxydeoxybenzoin.Because of the protection of methyl group,the reactivity of hydroxy groups was reduced and the yields of Houben-Hoesch and Friedel-Crafts reaction reached to 81.3% and 94.5% respectively.The yield of demethylation was 93.8%.The effects of catalyst amount and reaction temperature were investigated,and the optimal process parameters were as follows：（1）in Friedel-Crafts reaction,the ratio of catalyst（aluminum chloride）and 1,3,5-trimethoxybenzene 1.1∶1,reaction temperature 25 ℃,（2）in demethylation,the ratio of demethylation reagent and 2,4,6-trimethoxydeoxybenzoin 1.2∶1,reaction temperature 82 ℃.The product was characterized with 1H NMR and MS.