Preparation method of 3-chloro-4-fluoro-5-trifluoromethyl trifluoroacetophenone

The invention relates to the technical field of organic chemical synthesis, and discloses a preparation method of 3-chloro-4-fluoro-5-trifluoromethyl trifluoroacetophenone, which comprises the following steps: A) dissolving 2-fluoro-3-chlorobenzotrifluoride in a first solvent, and adding a bromination reagent while stirring to prepare an intermediate (2); and B) adding magnesium metal into a second solvent, slowly dropwise adding a solution formed by dissolving the intermediate (2) into the second solvent, stirring for reaction, and then adding the intermediate (3) to prepare the 3-chloro-4-fluoro-5-trifluoromethyl trifluoroacetophenone. According to the preparation method, 2-fluoro-3-chlorobenzotrifluoride is taken as a raw material, a pesticide and medical intermediate 3-chloro-4-fluoro-5-trifluoromethyl trifluoroacetophenone is synthesized through bromination and Grignard reaction in sequence, the total yield of the prepared 3-chloro-4-fluoro-5-trifluoromethyl trifluoroacetophenone reaches 65% or above, an