Hydrochloric Acid → 3-Chloro-2-fluoro-5-(trifluoromethyl)benzoic acid

Participants

Reaction Steps

To a solution of 3-chloro-2-fluoro-5-trifluoromethyl-benzaldehyde (1.0 g, 4.41 mmol) in acetone (15 ml) and water (3 ml) was added potassium permanganate (0.837 g, 5.3 mmol, 1.2 equiv.) and the corresponding dark violet reaction mixture was stirred for 30 min to achieve full conversion. The solvents were removed under vacuum and the dark suspension was quenched upon addition of sodium sulfite solution (sat., 20 ml). The dark violet solid was filtered off and washed with water (10 ml). The turbid light brown mother liquor was treated with HCl (25%, 3 ml, 92.3 mmol, 20.9 equiv) adjusting the pH to 1 and CH2Cl2 (50 ml) was added. The phases were separated, the organic phase was washed with water (20 ml), whereas the aqueous phase was washed with CH2Cl2 (20 ml). The combined organic phases were dried over sodium sulfate, filtered and the solvent was exchanged under vacuum with methyl cyclohexane (35 ml). The turbid suspension was concentrated under vacuum, the white precipitate was filtered off and the crystals were dried under vacuum until weight constancy to yield the product as white crystals (1.02 g, 93.8% yield).

Provenance & Evidence