Oxidation of 4-nitro-o-xylene with nitric acid using N-hydroxyphthalimide under phase transfer conditions

4-Nitro- o -xylene was selectively oxidized to 2-methyl-4-nitrobenzoic acid using dilute nitric acid as the oxidizing agent under atmospheric pressure. The oxidation of 4-nitro- o -xylene was effectively promoted by an addition of radical initiators. Under reflux, 2-methyl-4-nitrobenzoic acid was afforded in high yield using nitric acid combined with N -hydroxyphthalimide, cobalt dichloride (CoCl 2 · 6H 2 O), manganese acetate (Mn(OAc) 2 · 4H 2 O) and phase transfer catalyst.