Abstract:

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.

摘要：

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。