Sulfuric Acid → 4-Cyanobenzoic acid

Participants

Reaction Conditions

Reaction Steps

p-Cyanobenzamide (146 g) which had been synthesized separately and water (584 g) were placed in a four-neck flask, and the mixture was cooled to 15° C. with stirring. Subsequently, an aqueous solution (1775 g) of sodium hypochlorite (effective chlorine 12%) was added to the reaction mixture over six hours while a 50% aqueous solution of sulfuric acid was added so as to maintain the pH of the mixture at 5-6. Liquid chromatographic analysis revealed that the reaction mixture contained 145.5 g of crude p-cyanobenzoic acid (yield 99%). To the reaction mixture, concentrated sulfuric acid was added so as to adjust the pH to 3.0 and precipitate p-cyanobenzoic acid from its salt. The precipitate was dissolved by adding methanol (820 g) with heat, and the solution was cooled for crystallization, to thereby obtain 138.9 g of p-cyanobenzoic acid having a purity of 99.5% (yield 94%).

Provenance & Evidence