PRODUCTION OF 2,3,5,6-TETRAFLUORO-4-MERCAPTOBENZOIC ACID

摘要

PURPOSE:To easily produce the titled compound useful as a starting raw material for the synthesis of polymeric materials, liquid crystal materials, etc., in high yield, by reacting pentafluorobenzoic acid with a thiolation agent in an aqueous medium at a temperature within a specific range and contacting the reaction product with an acidic substance. CONSTITUTION:Pentafluorobenzoic acid and a thiolation agent are used as raw materials and heated at 40-100 deg.C, preferably 60-90 deg.C in an aqueous medium to produce a salt of tetrafluoro-4-mercaptobenzoic acid. The produced reaction mixture is precipitated with an acidic substance such as aqueous solution of sulfuric acid or hydrochloric acid to obtain the objective compound. The thiolation agent used in the above process is an alkali metal hydrogen sulfide or alkali metal sulfide. The amount of the thiolation agent can be decreased when a basic substance is present in the reaction system. The basic substance is preferably an alkali metal hydroxide.