Urea → 2-Chloro-4-hydroxybenzoic acid

Participants

Reaction Conditions

Reaction Steps

4-amino-2-chlorobenzoic acid (10 g, 58 mmol) was dissolved in H2SO4 (12 N, 120 mL) with heating. After cooling the solution in an ice-bath aqueous NaNO2 (2.5 M, 25 mL) was added dropwise such that the internal temperature remained at 5° C. Urea was added to the mixture for after stirring for 15 minutes to destroy excess NaNO2 (monitored by starch iodine test). CuSO4 (100-200 mg) was added and the mixture was heated to 90° C. until evolution of gas stopped. After cooling, the mixture was extracted with ethyl ether (3×). The combined organic fractions were extracted with 3N NaOH (3×). The combined aqueous layer was acidified with conc. HCl and the product was extracted with ethyl ether (3×). The organic fractions were washed with water, brine, and dried over MgSO4. The crude product was introduced into a silica gel column and eluted with ethyl acetate/hexane (1/1) to afford 2-chloro-4-hydroxybenzoic acid.

Provenance & Evidence