Sulfuric Acid → (3-Hydroxy-4-methoxy-2-nitrophenyl)(phenyl)methanone

Participants

Reaction Steps

To a stirred solution of 3-hydroxy-4-methoxybenzophenone (10.0 g, 43.8 mmol) in dichloromethane (100 mL) at room temperature was added tetrabutylammoniumhydrogen sulphate (0.74 g, 5 mol %) followed by isopropyl nitrate (11.5 g, 87.6 mmol). Sulphuric acid (96%, 10 mL) was then added dropwise causing a gently exothermic reaction, and, after stirring for forty minutes, the reaction mixture was poured onto water (300 mL). The phases were separated and the aqueous phase was extracted by dichloromethane (30 mL). The combined organic phases were washed with brine and dried over anhydrous sodium sulphate. Filtration and evaporation of the solvent (40° C., water aspirator pressure) afforded a solid residue which was recrystallised from a small volume of ethanol (96%, 10 mL) to afford yellow crystals, (7.97 g, 67%) of m.p. 137–139° C., identified by NMR as the ortho-nitrated title product. Concentration of the mother liquors and subsequent chromatography on silica gel using a petroleum ether:ethyl acetate solvent mixture (2:1) allowed the isolation of a small amount of a minor product, corresponding (TLC) to a standard of the para-nitrated product, 3-hydroxy4-methoxy-6-nitrobenzophenone (1.43 g, 12%), m.p. 154–156° C. (79% combined yield, Ortho:Para selectivity, 5.6:1)

Provenance & Evidence