采用二硫化钠合成巯基乙酸

介绍了采用二硫化钠合成巯基乙酸的新方法。以硫化钠和硫磺为基本原料制备二硫化钠,二硫化钠与氯乙酸钠合成2,2′-二硫代双乙酸钠,再用硫氢化钠和亚硫酸钠还原,经酸化、萃取、蒸馏,得到巯基乙酸。探讨了反应物浓度、反应温度、反应时间及酸化用酸的种类对巯基乙酸产品的影响。得出了最佳工艺条件:n硫化钠∶n硫∶n氯乙酸=1.4∶1.68∶1(物质的量比);硫化钠溶液的质量分数15%;合成2,2′-二硫代双乙酸钠时的反应温度45℃,反应时间30min;采用盐酸酸化还原。在此条件下,产品收率可达92.6%。

Synthesis of thioglycolic acid by sodium disulfide

A new method of synthesizing thioglycolic acid by sodium disulfide is presented. Sodium disulfide is prepared by sodium sulfide and sulfur, and 2, 2＇-dithio sodium diacetate is prepared by sodium disulfide and chloroacetic acid. 2, 2＇-Dithio sodium diacetate is reduced by sodium hydrosulfide and sodium sulfite, then acidated, extracted and distilled, the thioglycolic acid product is prepared finally. The effects of concentration of reactants, reaction temperature, reaction time and the type of acid on the product are discussed. The results show that the optimum conditions are as follows： the molar ratio of sodium sul- fide, sulfur to chloroacetic acid is 1.4 ： 1.68 ：1, the mass fraction of sodium sulfide is 15%, the reaction time is 30 minutes and hydrochloric acid is used as reactant. In these cases, the 92. 6% the reaction temperature is 45 ℃, yield of thioglycolic acid can reach