2-氨基-5-对羟基苯基-1,3,4-噻二唑及其席夫碱的合成

Synthesis of 2-Amino-5-(p-hydroxyphenyl)-1,3,4-thiadiazole and Its Salicylaldehyde Schiff Base

POCl3催化对羟基苯甲酸(1)和氨基硫脲(2)反应合成了5-(对羟基苯基)-2-氨基-1,3,4-噻二唑(3);3与水杨醛缩合制得对应的席夫碱,其结构经1HNMR和IR确征。合成3的较适宜反应条件为:150 mmol,250mmol,POCl330 mL,第一步于80℃反应80 min,第二步于110℃反应4 h,混合溶剂[V(DMF)∶V(水)=1∶2]的重结晶效果最好。在此条件下,3的收率达80.3%。

2-Amino-5-（p-hydroxyphenyl） -1,3,4-thiadiazole （ 3 ） was synthesized by reaction of p- hydrobenzoic acid（l） and thiosemicarbazide（2） using POCl3 as a catalyst. The Schiff base of 3 were prepared by condensation reaction between 3 and alicylaldehyde. The structures were characterized by ^1H NMR and IR. The appropriate reaction conditions of synthesizing 3 in yield of 80.3% were as follows： 1 and 2 were 50 mmol; POCl3 was 30 mL; first and second step reactions were carried out at 80 ℃ for 80 rain and at 110 ℃ for4 h, respectively; recrystallization solvent was V（DMF） ： V（H2O） = 1 ： 2. The yield was 80.3% under the conditions.