Improvement of the synthesis of 2-methyl-5-methoxy benzoic acid ethyl ester
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摘要: 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。
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关键词:
- 2-甲基-5-硝基苯甲酸 /
- 2-甲基-5-甲氧基-苯甲酸乙酯 /
- 合成工艺
Abstract: Objective To improve the synthetic process of 2-methyl-5-methoxy benzoic acid ethyl ester. Methods The target compounds were prepared from 2-methyl-5-nitro-benzoic acid through esterification, 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 place of the NaH as deacid 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. -
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