A novel green synthesis of o-nitrobenzoic acid by aerobic oxidation of o-nitrotoluene with aqueous ethanol instead of pure methanol as the solvent and substituted iron porphyrins as biomimetic catalysts was investigated. The effects of six iron porphyrins with different peripheral substituents on the above reaction were studied. It was found that all iron porphyrins had catalytic activity

and the substituents from strong electron donating group (—OH) to electron withdrawing group (—NO2) had a remarkable effect on the selectivity of o-nitrobenzoic acid and a insignificant effect on the activity (conversion of o-nitrotoluene). Among the six iron porphyrins T(p-Cl)PPFeCl had the highest catalytic activity and selectivity at the same time. By introducing a stronger electron withdrawing substituent

such as —NO2 or strong electron donating group

such as —OHaround the porphyrin rings resulted in low catalytic activity and selectivity. Moreover

the effects of different process parameters

such as ethanol concentration

NaOH concentration

dioxygen pressure

temperature

reaction time and initial concentration of o-nitrotoluene on the above reaction were examined

and optimal conditions were obtained. The conversion of o-nitrotoluene

the selectivity and yield of product could reach 79. 7%

95. 8% and 76. 3% respectively by using aqueous ethanol of 80% instead of pure methanol as solvent and T (p-Cl)PPFeCl as catalyst

and the reaction was carried out under optimal conditions

such as NaOH concentration of 3. 75 mol·L-1

2. 0 MPa O2 at 55℃ for 12 h.