2,5-二(4-氨基苯基)-1,3,4-噁二唑合成方法的优化

建立了一种2,5-二(4-氨基苯基)-1,3,4-噁二唑的最佳合成方法。以对硝基苯甲酸和盐酸氨基脲为原料，多聚磷酸为脱水剂，150~160℃的条件下反应2h，高收率(89%)制得中间体2,5-二(4-硝基苯基)-1,3,4-噁二唑；然后在DMF溶剂中以Na2S为还原剂，于100℃的条件下反应4h，中间体还原得到目标产物2,5-二(4-氨基苯基)-1,3,4噁二唑。此反应具有时间短、收率高且后处理简单、产物容易提纯等优点。

An optimized synthesis of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole

An optimized two-step synthesis of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole has been established.The reaction of 4-nitrobenzoic acid and semicarbazide hydrochloride at 150-160 ℃ for 2 h,using polyphosphoric acid as the dehydrating reagent,afforded 2,5-bis(4-nitrophenyl)-1,3,4-oxadiazole in 89% yield.This was subsequently reduced with Na2S in DMF at 100 ℃ for 4 h,to give the title compound in 85% yield.The as-prepared title compound is sufficiently pure for further uses.