2-甲基-5-甲氧基苯甲酸乙酯的合成工艺改进

目的探索2-甲基-5-甲氧基苯甲酸乙酯的合成工艺改进方法。方法以2-甲基-5-硝基苯甲酸为起始原料，经酯化反应，铁粉／醋酸还原，重氮化水解反应，甲基化反应等4步反应制得2-甲基-5-甲氧基苯甲酸乙酯。结果还原反应中，用廉价的铁粉／醋酸替代文献采用的昂贵的钯碳／氢气还原体系，收率达95％；甲基化反应中，以碳酸钾替代文献中的NaH，收率达89．1％，新合成工艺的收率由文献收率的63．21％提高到76．33％。结论本方法提出了一条操作简便、条件温和、成本较低并适合放大制备的2-甲基-5-甲氧基苯甲酸乙酯的合成工艺路线。

Improvement of the synthesis of 2-methyl-5-methoxy benzoic acid ethyl ester

Objective To improve the synthetic process of 2-methyl-5-methoxy benzoic aeid ethyl ester. Methods The target compounds were prepared from 2-methyl-5-nitro-henzoie acid through esterifieation, reduction, diazotization hydrolysis and methylation. Results In the procedure of reduction, Pd/H2 system was replaced by Fe/AcOH with a yield of 92.7%. In the produce of methylation , potassium carbonate were used to take plaee of the Nail as deaeid reagent with a yield of 89.1% . The yield of the new synthesis process was promoted from 75% to 89.1%. Conclusions This study provided a synthesis process route of 2-methyl-5-methoxy benzoic acid ethyl ester with simple operation, mild reaction condition, low price , which was suitable for the amplification of the preparation.