2-(2,4-二羟基苯基)-2H-苯并三唑合成方法的改进

Improvement of synthesis method of 2-(2,4-dihydroxyphenyl)-2H-Benzotriazol

通过重氮化、偶合、还原反应成功地合成出目标化合物．尤其对还原剂进行了研究．试验结果表明：自制的还原剂二氧化硫脲在氢氧化钠的乙醇．水介质中可以成功地将偶氮化合物还原成目标分子．该还原法具有工艺简单、反应时间短、产率较高等优点．同时对还原剂用量对收率的影响也作了研究，得到了较佳的工艺条件：偶氮化合物6．5卧氢氧化钠12．5g、水60mL、乙醇（95％）60mL、自制的还原剂二氧化硫脲10g，反应温度60-65℃，反应时间2h，产品最高收率为64．3％．另外，用熔点、红外光谱、元素分析等对目标产物进行了结构袁征．

2-(2,4-dihydroxyphenyl)-2H-Benzotriazol is successfully prepared by azo-reaction,coupling and reduction.The sorts of reductant are researched.The results show that azo compounds can be reduced with self-made reductant——thiourea dioxide using an aqueous solution of ethanol in the presence of sodium hydroxide.The reduction method is of simpler technology,shorter reaction time and higher yield.The influence of the dose of thiourea dioxide on the yield of the objective product is investigated,and the better technological conditions are obtained:azo compound of 6.5g,sodium hydroxide of 12.5g,aqueous ethanol solution of 120mL (V/V=1:1),thiourea dioxide of 10g,reaction temperature of 60～65 ℃,reaction time of 2h.The yield of 2-(2,4-dihydrophenyl)-2H-Benzotriazol is up to 64.2%.The structure of 2-(2,4-dihydrophenyl)-2H-Benzotriazol is characterized by IR,melting point and elementary analysis.