Preparation method of 3, 4-dichloro-2-fluoroaniline

The invention discloses a preparation method of 3, 4-dichloro-2-fluoroaniline, which comprises the following steps: (1) taking 1, 2, 3-trichlorobenzene as a raw material, and carrying out nitration reaction to obtain 2, 3, 4-trichloronitrobenzene; (2) the 2, 3, 4-trichloronitrobenzene is subjected to an ammonolysis reaction, and 2, 3-dichloro-6-nitroaniline is obtained; (3) carrying out diazotization reaction on the 2, 3-dichloro-6-nitroaniline, fluorine-containing inorganic acid and sodium nitrite in an organic solvent to generate diazonium salt, and then heating and decomposing to obtain 2-fluoro-3, 4-dichloronitrobenzene; and (4) reducing the 2-fluoro-3, 4-dichloronitrobenzene, so as to obtain the 3, 4-dichloro-2-fluoroaniline. According to the method, 1, 2, 3-trichlorobenzene serves as a raw material, and 3, 4-dichloro-2-fluoroaniline is obtained through the processes of nitration, ammonolysis, diazotization, decomposition, reduction and the like; the method provides a synthetic route of 3, 4-dichloro-2-f