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

Participants

Reaction Conditions

Reaction Steps

To an aqueous solution of sodium hypochlorite (15.3 ml, 25.7 mmol, 1.2 equiv.) and sodium bromide (2.6 g, 25.7 mmol, 1.2 equiv.) in sodium hydroxide solution (47%, 4.55 ml, 53.5 mmol, 2.50 equiv.) and water (12.5 ml) was added slowly (during 25 min) at 50° C. 3-chloro-2-fluoro-5-trifluoromethyl-benzaldehyde (5.0 g, 21.4 mmol). The reaction mixture was stirred at 50° C. for 60 min, cooled to ambient temperature and quenched upon addition of aqueous sodium sulfite solution (20%, 16.2 ml, 25.7 mmol, 1.2 equiv.) to give a light turbid suspension. The suspension was stirred for 15 min, treated with HCl (37%, 5.0 ml, 59.1 mmol, 2.76 equiv.) adjusting the pH to 1, whereupon a white precipitate formed. This precipitate was extracted with toluene (30 ml), the organic phase was washed with brine (30 ml), whereas the aqueous phase was washed with TBME (30 ml). The combined organic phases were dried over sodium sulfate, filtered and the solvent was removed under vacuum to give the crude product as light yellow solid (5.13 g, 98.8% yield). The crude product was dissolved in hot cyclohexane (25 ml), and the solution was cooled to ambient temperature, whereupon white crystals precipitated. The crystals were filtered off, washed with cyclohexane (5 ml) dried under vacuum until weight constancy to give the title compound as white crystals (3.65 g, 69.6% yield).

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