Continuous Process for Synthesis of Thioglycolic Acid in the Combination Reactors

Thioglycolic acid (TGA) was continuous synthesized from chloroacetic acid (CAA) and sodium hydrosulfide (SHS) under common pressure in the combination reactors. Effects of the process conditions on the yield of TGA were investigated, such as molar ratio of CAA to SHS, mass fraction of material, reaction time and temperature in the tank and tubular reactors respectively. The yield of TGA beyond 90% was obtained under such optimal conditions as molar ratio of chloroacetic acid to sodium hydrosulfide was 1:2.5, the concentration of chloroacetic acid and sodium hydrosulfide were 20% and 15% mass fraction respectively, the residence time of continuous tank reactor was 10 min, reaction temperature 10°C, the residence time of tubular reactor was 9 min, reaction temperature 55°C. The higher yield of TGA was obtained in continuous operation by this optimal process.