Sulfuric Acid → 4-Chloro-3-cyanobenzoic acid

Participants

Reaction Conditions

Reaction Steps

To a stirred mixture of conc. sulfuric acid (60 mL) and water (95 mL) containing 3-amino-4-chlorobenzoic acid (10.0 g, 57.1 mmol) was added sodium nitrite (10.0 g, 145 mmol) at 0° C. The mixture was stirred at 0° C. for 2 hours, and added to a stirred mixture comprising a mixture of water (250 mL) and benzene (175 mL) containing copper cyanide (7.1 g, 79.3 mmol), potassium cyanide (21.7 g, 333 mmol), potassium carbonate (285 g, 2.06 mmol) at a temperature not higher than 15° C. The resulting mixture was heated under stirring at 80° C. for one hour, cooled to room temperature, stirred under ice-cooling, and filtered using Celite to collect insolubles. The insolubles were washed with benzene (100 mL) and ether (100 mL). The aqueous portion was taken out, and made to pH 2 by addition of conc. hydrochloric acid under stirring and ice-cooling. The aqueous portion was subjected to extraction with ether (200 mL×2), dried over anhydrous sodium sulfate, and placed under reduced pressure to distill the solvent off. The residue was repeatedly purified by silica gel column chromatography (ethyl acetate/hexane), to obtain 2.0 g (yield 19%) of the titled compound as a pale yellow crystalline product.

Provenance & Evidence