Oxidation Properties And Selective Synthesis Of 4-nitro-ο-xylene

2-Methyl-4-nitrobenzoic acid and 4-nitrophthalic acid were prepared by selective nitration and oxidation with o-xylene as starting material.The selective nitration of o-xylene with nitrogen dioxide showed good property. It was helpful to improve the conversion of o-xylene and the yield of 4-nitro-o-xylene. The sulfuric acid presented better property than other Brφnsted acids on nitration of o-xylene with nitrogen dioxide. The conversion of o-xylene was 96.7%, and the yield of nitro-o-xylene was 81.2%. In the presence of Lewis acid - bismuth trichloride, the ratio of 4-nitro-o-xylene and 3-nitro-o-xylene was increased to 3.83. Acetic anhydride also showed good property on the nitration of o-xylene with nitrogen dioxide. The substrate could be thorough transformed and the 4-nitro-o-xylene of 60.2% yield was highly selectively obtained.The oxidation of 4-nitro-o-xylene using nitric acid and hydrogen peroxide was explored. The radical initiators N-hydroxyphthalimide was effective in the promotion of oxidation reaction. Under reflux conditions, 2-methyl-4-nitrobenzoic acid of 61.2% yield and 4-nitrophthalic acid of 20.4% were prepared by using nitric acid in the synergistic effect of cobalt dichloride. For the NHPI-CoCl2-PTC (Phase Transfer Catalyst) system, only 2-methyl-4-nitrobenzoic acid was obtained in the yield of 29.4% by using hydrogen peroxide as oxidizing agent. The target compounds were characterized by IR and 1H NMR analyses.