Sulfuric Acid → 3,5-Dichloro-4-fluorobenzoic acid

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Reaction Conditions

Reaction Steps

3,5-dichloro-4-fluorobenzoyl chloride can be prepared as follows: To a round bottom flask with nitrogen purge through a 10% aqueous NaOH trap, was added 3,5-dichloro-4-flurobenzotriflouride (5.00 g, 21.46 mmol, Aldrich), concentrated sulfuric acid (4.30 g, 42.92 mmol), and finally chlorosulfonic acid (5.15 g, 43.78 mmol). The reaction began to bubble immediately. After the bubbling subsided, the mixture was heated to 50° C. for 1 hr, cooled to room temperature, and added cautiously to stirred ice water. This was extracted twice with methylene chloride. The combined extracts were washed with water and brine, dried over magnesium sulfate, filtered, and evaporated to give a white solid (2.19 g) of 3,5-dichloro-4-fluorobenzoic acid in 49% yield. 1H NMR (CD3COCD3, 300 MHz) δ (ppm): 7.95 (d, 2H).

Provenance & Evidence