PURPOSE: To prepare the titled compound useful as an intermediate raw material of agricultural chemicals, pharmaceuticals, etc., economically in an industrial scale, in high yield, by reacting O-halo-benzoic acid directly with sulfur in the presnce of an alkali metal hydroxide.
CONSTITUTION: The thiosalicylic acid and dithiosalicylic acid of formula II and formula III are prepared by reacting the O-halobenzoic acid of formula I (X is halogen) with sulfur in the presence of an alkali metal hydroxide such as NaOH, KOH, etc. The compound of formula I is preferably O-chlorobenzoic acid in view of economicity; however, O-bromobenzoic acid and O-iodobenzoic acid may be used in some cases. The reaction yield cannot be improved by using the alkali metal hydroxide as a single substance, and it is preferable to use the hydroxide as a mixture to achieve high yield. The reaction temperature is usually 200W 350°C, however, it is preferable to carry out the reaction at 250W300°C.
KAMIYAMA TSUTOMU
KATOU KUNIKOSHI
