The Application Of Combination Reactor In The Synthesis Of Thioglycolic Acid

Thioglycolic acid (TGA) is an important fine chemical intermediates as it contains both carboxyl and sulfhydryl, it is widely used in beauty salons, analysis, pharmaceutical, PVC production and other fields. The research and production of TGA in china is earlier but still have great laps compared with developed countries which mainly shows backward production technology, high cost, low purity and can not meet the needs of domestic enterprises, therefore, the needed quantities of thioglycolic acid are still imported largely. According to this situation, the paper synthesis and optimize the process of thioglycolic acid with sodium hydrosulfide and chloroacetic acid under atmospheric pressure, which can improve the yield effectively, achieve the continuous operation and provide basic data for the industrial production of thioglycolic acid.The paper studied the effects of material concentration, material molar ratio, stirring speed of tank reactor, reaction time and temperature on the yield of thioglycolic acid (TGA) with orthogonal and single factor experiment and optimized the process of two series of tank reactor that synthesized the thioglycolic acid continuously under atmospheric pressure, which used sodium hydrosulfide and chloroacetic acid as material. The results showed the better conditions as follows:the concentration of sodium hydrosulfide and chloroacetic acid were 20%and 15%respectively, the molar ratio of sodium hydrosulfide and chloroacetic acid was 2.5:1, the stirring speed was 200r/min, the residence time ofⅡ#tank was 29.9min the residence time ofⅠ# tank was 34.2min,the temperature of II tank was 50℃, the temperature ofⅠ# tank was 10℃. Under this conditions, the yield of thioglycolic acid can get 63.01%。The tank reactor is in favor of mixing of raw materials but back mixing is also serious in continuous process, leading the low yield of thioglycolic acid. On the basis of two series of tank reactor, through the comparative analysis of reactor types and reaction characteristices. we used the self-designed tank-tube combination reactor instead of the original two series of tank reactor and optimized the process, the results showed that the optimum conditions were:the concentration of sodium hydrosulfide and chloroacetic acid were 20%and 15%respectively, the molar ratio of sodium hydrosulfide and chloroacetic acid was 2.5:1, the stirring speed was 200r/min, the residence time of tank reactor was 10min. the temperature of tank reactor was 10℃, the residence time of tubular reactor was 9min, the temperature of tubular reactor was 55℃,under the optimum conditions the yield of thioglycolic acid can get beyond 90%.