电还原二硫代二乙酸制备巯基乙酸

Prepare Thioglycolic Acid by Electroreduction of Dithiodiglycolic Acid

以硫代硫酸钠法合成的巯基乙酸(TGA)和二硫代二乙酸(DTDGA)混合物为原料,研究了DTDGA电还原制备TGA的工艺条件对DTDGA转化率、TGA收率和电流效率的影响规律。实验结果表明:以铅为阴极材料,在DTDGA初始质量分数为4.75%,温度50℃,电流密度800 A/m2,通电量为理论通电量2.0倍的工艺条件下电解,DTDGA转化率为98.51%、TGA收率为93.74%,电流效率为45.16%。与传统的硫代硫酸钠法(或Bunte盐法)合成TGA相比,不仅省去了昂贵的金属锌粉的消耗,而且使吨产品TGA的氯乙酸单耗下降了0.69 t。

Mixture of thioglycolic acid（TGA） and dithioglycolic acid （DTDGA） was synthesized by the method of sodium thiosulfate, and used as raw materials to prepared TGA by further electroreduction of DTDGA. Under the optimal conditions, lead plate was used as cathode, original weight percent of DTDGA was 4.75%, reaction temperature was 50 ℃, the current density was 800 A/m^2, and the electrical charge was 2 times of theoretical value. Conversion of DTDGA was 98.53%, total yield of TGA was 93.76%, and the current efficiency was 45.11%. Compared with conventional sodium thiosulfate method （or the Bunte salt method ） for preparing TGA, the electroreduction technology dispenses with the costly zinc powder and decreases the consume of ehloroaeetie acid by 0.69 t in producing each ton of TGA.