Synthetic method for bifenazate

The invention relates to a synthetic method for bifenazate. The method comprises the following specific synthetic sections: step 1, performing nitration: mixing a 4-hydroxybiphenyl solution and a toluene solution under stirring for a reaction, and adding a HNO3 solution dropwise for a reaction to obtain a nitration reaction solution; step 2, performing methylation: mixing the nitration reaction solution and anhydrous sodium carbonate powder for a reaction, and adding a dimethyl carbonate solution dropwise for a reaction to obtain a methylation reaction solution; step 3, performing hydrogenation: throwing the methylation reaction solution, hydrogen gas, and Raney nickel into a reaction kettle for a reaction to obtain a hydrogenation reaction liquid; step 4, performing hydrazination: performing a primary hydrazination reaction, performing a secondary hydrazination reaction, performing filter pressing, performing a tertiary hydrazination reaction, and performing secondary filter pressingto obtain a condensation reaction liquid; step 5, performing condensation: mixing a third hydrazine compound, an ethyl acetate solution and an isopropyl chloroformate solution for a reaction to obtaina bifenazate mixed liquid; and step 6, performing purification: performing desolvation, performing crystallization, performing centrifugation, performing washing, performing secondary centrifugation,and performing drying to obtain the finished bifenazate. The method provided by the invention has the effect of improving purity of the bifenazate product.