采用硫化钠法合成巯基乙酸

Synthesis of thioglycolic acid by sodium sulfide

研究了巯基乙酸的主要合成方法,即选取硫化钠法作为研究对象,通过向体系中加入盐酸,有效地增加了活性组份HS-的浓度,并利用反应产生的硫化氢气体部分地抑制了副反应的发生.此外,探讨了合成工艺的影响因素,得出优化工艺条件为:反应物的量比n(Na2S)∶n(ClCH2COOH)∶n(HCl)=2.20∶1.00∶0.72,体系的pH值为10～11,反应温度、时间、压力分别为75℃,120min,0.4MPa;在此条件下,转化率达到65.6%.压力试验结果表明,反应的转化率随压力升高而增大.

The methods of synthesis of thioglycolic acid are presented. In order to increase the concentration of HS- and reaction pressure, which produced by H2S gas can restrain subsidiary reactions, hydrochloric acid is introduced into the kettle. The effects of reaction temperature, reaction time, reactant ratio, pH value on the conversion are investigated. The results show that the conversion can reach 65.6% when the reactant ratio n(Na2S)∶n(ClCH2COOH)∶n(HCl) is 2.20∶1.00∶0.72, reaction time is 120 min, reaction temperature is 75 ℃, reaction pressure is 0.4 MPa and pH value is 10～11.The experiment about reaction pressure indicates that the conversion will increase with the raise of pressure.