Phenol → 2-Nitro-4-phenoxybenzoic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 2,4-dinitrobenzoic acid [Aldrich] (1.06 g, 5 mmol) in dichloromethane (20 ml) was treated with oxalyl chloride (2 ml) and 1 drop DMF. Vigorous evolution of gas occurred which ceased after 1 hour. The solution was evaporated to the yellow acid chloride. A solution of phenol (1.5 g, 15.5 mmol) in DMF (20 ml) was introduced into a second flask charged with sodium hydride (480 mg, 60% oil dispersion, 12 mmol). When all the hydride had dissolved this solution was treated with the acid chloride, portionwise over five minutes. The solution was then heated to 60° C. for 12 h, cooled, the solvents removed by evaporation in vacuo, and the residue treated with a solution of 40% sodium hydroxide (50 ml) and ethanol (50 ml). The mixture was stirred at RT for 12 hours then acidified to pH 2 with (2M aq HCl) and extracted into ethyl acetate (3×100 ml). The combined organic phase was washed with saturated brine (50 ml), dried (MgSO4), filtered, and evaporated to a yellow solid. This was purified by flash chromatography (ethyl acetate-hexane) to give 2-nitro-4-phenoxy-benzoic acid (894 mg, 69%);

Provenance & Evidence