Water → 4-Methoxy-3-sulfanylbenzoic acid

Participants

Reaction Steps

A mixture of 3-chlorosulfonyl-4-methoxybenzoic acid (4.76 g; that is prepared as described in Reference Example 44) in dry toluene (500 mL) stirred at room temperature is treated with triphenylphosphine (19.9 g) in one portion. The mixture is stirred and heated at 80° C. overnight, and then it is cooled, and treated with water (25 mL) and dioxane (25 mL), and the resulting solution is heated on a steam bath for 1 hour. The reaction mixture is allowed to cool to room temperature, and the organic layer is collected and concentrated. The resulting residue is partitioned between ethyl acetate (200 mL) and aqueous sodium hydroxide solution (500 mL; 2 N). The aqueous layer is separated, acidified by treatment with concentrated hydrochloric acid, and extracted with ethyl acetate (100 mL). The extract is washed with water (100 mL), dried over magnesium sulfate and concentrated, to give 3-mercapto-4-methoxybenzoic acid in the form of a white solid (3.4 g), m.p. 208-210° C.

Provenance & Evidence