Synthesis method of 2-methyl-4-nitrobenzoic acid

The invention discloses a synthesis method of 2-methyl-4-nitrobenzoic acid, and belongs to the technical field of chemosynthesis. According to the method, methylbenzene is used as raw materials; reaction liquid formed by mixing concentrated nitric acid and concentrated sulfuric acid is added for mixing; after being washed by a sodium hydroxide solution, the materials take an reaction with stannous chloride, iron powder and glacial acetic acid; then, hydrochloric acid is dropwise added for mixing to obtain 2-amino-5-nitrotoluene; then, the 2-amino-5-nitrotoluene is mixed with acetic acid and the concentrated sulfuric acid for taking a reaction; after the oxidization by an oxidizing agent of sodium perborate, temperature lowering by ice water and washing by deionized water are carried out; then, under the oxidization effect of an oxidizing agent of potassium permanganate, the materials are mixed with hydrochloric acid for reaction; then, still standing, suction filtering and drying are carried out, and the 2-methyl-4-nitrobenzoic acid is obtained. The synthesis method has the beneficial effects that the synthesis process is simple; the cost is low; byproducts are few; the yield of obtained products is as high as more than 95 percent; the purity is as high as more than 99 percent.