| Abstract: | A new methodology for the production of terephthalic acid ( 3 ) by the aerobic oxidation of p‐xylene ( 1 ) using a combined catalytic system of N‐hydroxyphthalimide (NHPI)/Co(OAc) 2/Mn(OAc) 2was developed. The oxidation of 1 under a dioxygen atmosphere in the presence of a catalytic amount of NHPI/NHPI(OAc) 2/Mn(OAc) 2at 100 °C for 14 h afforded terephthalic acid in 82% yield. Removal of Mn(OAc) 2 from the catalytic system resulted in considerable reduction in the yield of 3 . When the oxidation of 1 was carried out under a pressure of air (30 atm) at 150 °C, the reaction was completed within 3 h to give 3 in 84% yield. The oxidation of p‐toluic acid ( 2 ), which can be prepared by the oxidation of 1 using the NHPI/NHPI(OAc) 2 system at room temperature, by the NHPI/NHPI(OAc) 2/Mn(OAc) 2system under pressure of air (30 atm) at 150 °C gave 3 in 95% yield. N‐Acetoxyphthalimide (NAPI) was found to require a lower catalyst loading than NHPI, but oxidation with NAPI was slower. Thus, the oxidation of 1 catalyzed by NAPI (5 mol %)/Co(OAc) 2 (0.5 mol %)/Mn(OAc) 2 (0.5 mol %) under a dioxygen atmosphere (1 atm) in acetic acid at 100 °C gave 3 in 80% yield. |
