N-杂环卡宾催化对硝基苯甲醛的氧化酯化

以空气为氧化剂,研究了在N-杂环卡宾催化下,对硝基苯甲醛与9种醇的氧化酯化反应。考察了不同卡宾前体、卡宾前体的用量以及溶剂对收率和反应速率的影响。结果表明,当以对硝基苯甲醛摩尔分数10%的溴化3-乙基-4-甲基-5-羟乙基噻唑鎓盐为催化剂,过量的原料醇为溶剂时,可以有效地催化氧化对硝基苯甲醛进行酯化反应,收率为36%~64%,但当使用与对硝基苯甲醛等摩尔比的醇时,收率仅为9%~29%。

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Using air as the ultimate oxidant, a facile method for the oxidative esterification of para-nitrobenzaldehyde has been developed. The results demonstrated that the catalyst precursors, catalyst loadings and solvents have considerably effects on both the yields and reaction rates. A variety of para-nitrobenzonates were conveniently prepared with the yields of 36%~64% under the optimal reaction conditions, where the corresponding alcohols were used as the solvents, and the 3-ethyl-4-methyl-5-hydroxyethyl thiazole bromide salt as the catalyst precursor, with 10% molar fraction catalyst loading. Modest yields of 9%~29% were obtained if only stoichiometric amount alcohol was used.