Sulfuric Acid → 3,4-Difluoro-benzenesulfinic acid

Participants

Reaction Steps

To sodium sulfite (22.2 g, 176 mmol) in 80 ml water at RT was added dropwise over 20 min a solution of 3,4-difluoro-benzenesulfonyl chloride (5.00 g, 23.5 mmol) in 40 ml dioxane. 1 M aq NaOH (40 ml) was then added dropwise until the reaction mixture was pH 14 and the mixture was then allowed to stir at RT for a further 16 h. The mixture was then cooled to 0° C. and concentrated H2SO4 added until the reaction mixture was pH 1. The mixture was extracted three times with ethyl acetate and the combined organic phases washed with saturated aq NaCl solution and then dried with Na2SO4. Evaporation in vacuo yielded the title compound (4.21 g, 97%) as a white crystalline solid. MS (ISN): 177.1 M−H−

Provenance & Evidence