Dimethyl Sulfoxide → 2,3,4,5-Tetrafluorobenzoic acid

Participants

Reaction Steps

3,4,5,6-Tetrafluorophthalic acid (58 g) was added to a two liter flask. Dimethyl sulfoxide (230 ml) followed by triethylamine (11.5 ml) were then added and the mixture heated over a 20 minute period to 115°-120° C. The solution was heated with stirring at 115°-120° C. for another 35-40 minutes and then cooled with an ice bath. Demineralized water (580 ml) followed by n-butyl ether (250 ml) and toluene (350 ml) were added. Sulfuric acid (99%, 3.5 ml) was then cautiously added with stirring and cooling. The layers were separated and the aqueous layer extracted with two portions of toluene (580 ml and 290 ml). The combined organic layers were extracted with 2% aqueous sulfuric acid (3×150 ml). The organic layer was dried over anhydrous sodium sulfate (60 g) and Darco S-51 (11.5 g) was added. After filtering the mixture was concentrated under reduced pressure and the resulting solid dried under vacuum at 50°-60° C. for seven hours to give 2,3,4,5-tetrafluorobenzoic acid (44.3 g, 94%); mp 77°-80° C.

Provenance & Evidence