Hydrogen Bromide → 4-Bromo-2,5-difluoro-3-methylbenzoic acid

Participants

Reaction Steps

In 658 ml of 4.7% hydrobromic acid was suspended 26.3 g of 4-amino-2,5-difluoro-3-methylbenzoic acid, and 161 g of cupric bromide was added to the suspension. To this suspension was dropwise added a solution of 16.5 g of sodium nitrite in 165 ml of water over one hour with ice-cooling, and the resulting mixture was stirred for one hour at the same temperature and then at room temperature for two hours. To the reaction mixture was added 700 ml of toluene and the organic layer formed was separated, washed with 100 ml of conc. hydrochloric acid and then dried over anhydrous magnesium sulfate. The solvent was then removed by distillation under reduced pressure. To the residue obtained was added n-hexane and the resulting crystals were collected by filtration to obtain 29.5 g of colorless, crystalline 4-bromo-2,5-difluoro-3-methylbenzoic acid.

Provenance & Evidence