Synthesis method of chloronicotinyl insecticide clothianidin

The invention discloses a synthesis method of chloronicotinyl insecticide clothianidin. The synthesis method comprises the following steps: putting raw materials 2-chloro-5-chloromethylthiazole, 1,5-dimethyl-2-nitroimino-hexahydro-1,3,5-triazine and potassium carbonate in a water solution of tetra alkyl ammonium hydroxide to react and carrying out filtration, desolvation, extraction and concentration to obtain 1-(2-chlorothiazole-5-methyl)-2-nitroimino-3,5-dimethyl-hexahydro-1,3,5-triazine (compound II); hydrolyzing the compound II in a solution of alkylamine and carrying out freezing and filtration to obtain the clothianidin (I). According to the synthesis method, the raw materials undergo condensation reaction under the catalysis of tetra alkyl ammonium hydroxide, so that the reaction speed is high, the temperature is low, the selectivity is high, nearly no byproducts are generated and the operation is simple and convenient; the hydrolysis is carried out in the water solution or alcoholic solution of alkylamine, so that the reaction can be carried out under relatively mild conditions, less byproducts are generated, the reaction wastewater is less and the solvent can be recycled.