Selective Catalytic Oxidation Of Green Nitrotoluene

Nitrobenzaldehydes are important organic intermediates and have gained extensive attention of researchers all over the world because of their practical applications in pharmaceutical engineering and organic synthesis such as perfume and dye. A facile environmentally friendly and simple procedure has been described in this paper for the oxidation of nitrotoluene to the corresponding nitrobenzaldehyde using a H2O2/Metal Schiff base complexes catalyzed oxidation system in heterogeneous solution.Nitrobenzaldehyde was synthesized through condensation and oxidation reaction from nitrotoluene. The optimized reaction conditions of the condensation were at follows. The yield of2-nitrobenzaldehyde could reach81.5%, the yield of4-nitrobenzaldehyde could reach84.7%and the yield of3-nitrobenzaldehyde could reach63.5%.The new green avoids using bromine, tetrachloromethane and potassium permanganate in traditional oxidation, and hydrogen peroxide was used as the oxidation in the oxidation reaction. The process has mang advantages such as simple operation, mild reaction condition, high selecitivity and environmentally friendly. The catalytic system was recovered and reused.In addition, H2O2could provide further oxidation nitrobenzaldehyde to nitrobenzoic acid in the presence of NaOH. The yield of2-nitrobenzoic acid and4-nitrobenzoic acid could reach89.2%and91.7%separately in the presence of sodium hydroxide solution.The nitrobenzoic acid were synthesized when nitrotoluene were used as raw material through oxidation immediately with NaCIO catalyzed by Ni(2,2-bpy)2Cl2. The yield of crued2-nitrobenzoic acid could reach61%and4-nitrobenzoic acid could reach92%.This method avoids using the traditional method which requires the application of nitric acid, potassium permanganate, potassium dichromate and other environmental hazards reagents and avoids the risk of high-pressure autoclave apparatus. The paper using sodium hypochlorite as the oxidant, the reaction step is simple, requires low apparatus, green environmental protection.