Water → 2-Chloro-4-hydroxybenzoic acid

Participants

Reaction Conditions

Reaction Steps

4-amino-2-chlorobenzoic acid (10.01 g) was homogeneously dissolved in 12.5% sulfuric acid (400 ml) by heating to 70° C. and ice-cooled. To this suspension was added dropwise aqueous sodium nitrite solution (4.24 g/12 ml of water) at not more than 8° C. over 5 min. After 5 min, this solution was gradually poured into water (500 ml) at 80° C., upon which the solution foamed vigorously and turned into a red solution. The reaction mixture was stirred at 80° C. for 1 hr. After allowing to cool, the resulting product was extracted 3 times with diethyl ether. The organic layers were combined and washed successively with dil. hydrochloric acid, water and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated and a small amount of diisopropyl ether was added to the residue to allow for crystallization to give 2-chloro-4-hydroxybenzoic acid (6.32 g) as an orange powder.

Provenance & Evidence