Process for the preparation of thioglycolic acid

摘要

Preparation of thioglycolic acid (I) comprises reaction of monochloroacetic acid with hydrogen sulphide under pressure in the presence of tert. amines in solution. The novelty is that: (a) the H2S partial pressure above the reaction medium is maintained at at least 2 bars till the end of the reaction; and (b) the thioglycolic acid which is formed as its ammonium salt, is released by treatment with an acid.