Phenol → 2-Nitro-4-phenoxybenzoic acid

Temperature

60 °C

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%);

1. customThe solution was evaporated to the yellow acid chloride
2. temperaturecooled
3. customthe solvents removed by evaporation in vacuo
4. additionthe residue treated with a solution of 40% sodium hydroxide (50 ml) and ethanol (50 ml)
5. extractionextracted into ethyl acetate (3×100 ml)
6. washThe combined organic phase was washed with saturated brine (50 ml)
7. dry with materialdried (MgSO4)
8. filtrationfiltered
9. customevaporated to a yellow solid
10. customThis was purified by flash chromatography (ethyl acetate-hexane)

ORD record

ord-f7fa783a6cbe4226af95c3ddcbe56607

Source dataset

uspto-grants-2007_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07220777B2