合成噻吩-2,5-二甲酸的简便方法

Concise Synthesis of Thiophene-2,5-dicarboxylic acid

摘要:

在氯化亚锡的催化作用下，硫代二甘醇酸与过量的甲醇或乙醇回流反应合成了硫代二甘醇酸二甲酯 (Ia)或硫代二甘醇酸二乙酯(Ib)，反应的较佳条件是：SnCl2％，回流h，收率分别为93.5%和96.4%。然后在强碱氢氧化钾的作用下，化合物Ia或Ib与二水合三聚乙二醛经缩合和水解反应合成了噻吩-2,5-二甲酸(II)，反应的较佳条件是：n (硫代二甘醇酸二甲酯或硫代二甘醇酸二乙酯) : n (二水合三聚乙二醛) : n (氢氧化钾)＝1: 0.4: 4.4，在环己烷中回流5 h，收率为89.3%~90.0%。

Abstract:

Thiodiglycolic acid was refluxed with excess methanol or ethanol to obtain dimethyl thiodiglycolate (Ia) or diethyl thiodiglycolate (Ib) using stannous chloride as catalyst. The optimum conditions were SnCl2)=4.0％ and reflux time 3 h, and their yields were 93.5% or 96.4%, respectively. Compound Ia or Ib reacted with glyoxal trimer dehydrate to give thiophene-2, 5-dicarboxylic acid through condensation and hydrolyzation in the presence of potassium hydroxide. The optimal reaction conditions were n (dimethyl thiodiglycolate or diethyl thiodiglycolate) : n (glyoxal trimer dehydrate) : n (potassium hydroxide)＝1: 0.4: 4.4 and reflux time 5 h in cyclohexane. The yields of thiophene-2, 5-dicarboxylic acid were 89.3%~90.0%.