Environment-friendly preparation method of 2-chloro-4-nitro-6-bromoaniline

A preparation method of 2-chloro-4-nitro-6-bromoaniline comprises the following steps: (a) carrying out mixed acid nitration on o-dichlorobenzene, and continuing to apply the generated waste acid to anext nitration reaction; (b) purifying the obtained nitration product in an alcohol solvent to obtain 3,4-dichloronitrobenzene, and continuously applying the recovered alcohol solvent to a next purification process; (c) carrying out ammonolysis on the 3,4-dichloronitrobenzene in a water phase by adopting a specific catalyst to prepare o-chloro-p-nitroaniline, and continuously applying the recycled liquid ammonia to a next ammonolysis reaction; and (d) brominating o-chloro-p-nitroaniline in a hydrogen bromide and oxidant system, and recycling brominated waste acid liquid and bromine for a nextbromination reaction. The product obtained by the method is good in yield, high in purity and high in quality; and two waste acids and bromine in the product are recycled, so that the amount of wastewater is reduced. Compared