2,4-二甲基-3-氨基噻吩的合成

Synthesis of 2,4-Dimethylthiophene-3-amine

[方法]2,4-二甲基-3-氨基噻吩主要用于有机合成,是合成除草剂的重要中间体。以巯基乙酸和乙酰丙酮为起始原料,经过亲核加成、酯化、关环、水解、脱羧、还原等7步反应得到2,4-二甲基-3-氨基噻吩,并优化了关键的硝化反应。[结果]正交试验显示硝化反应的最优条件:反应温度15℃,3,5-二甲基噻吩-2-甲酸与乙酰硝酸酯的摩尔比1∶7,反应时间55 min。[结论]该路线简单经济,条件温和,收率高于其他路线,适合生产。

[Methods] The 2,4-dimethylthiophene-3-amine is one intermediate of S-dimethenamid,which was used in organic synthesis.In a previous study,the nitration was the hindered step of its preparation.Here,a new designed route was studied.The title compound was prepared from thioglycolic acid and acetyl-acetone via seven-step reactions including nucleophilic addition,esterification,cyclization,hydrolysis,nitration,decarboxylation and reduction.Nitration was optimized with orthogonal design technology.[Results] For the key reaction,the optimal condition of nitration was described： reaction temperature was 15 °c;the ratio of 3,5-dimethylthiophene-2-carboxylic acid to AcONO2 was 1：7;reaction time was 55 min.[Conclusions] The new route is simple,economical and available on a large scale.