Study On The Synthesis Process Of 2, 3-Dichloro-5-Trifluoromethylpyridine As An Important Intermediate Of Pesticides

2,3-Dichloro-5-trifluoromethylpyridine is an important organic intermediate of producing some high effective pesticides containing fluorine. It is prepared with 1,1,1-trichlorotrifluoroethane as a raw material through four steps. Compared with the traditional halogen substitution of the pyridine derivatives, this process has the advantages of low cost of the raw materials, simple operation and good yield. As a result, the process has high value of being studied and developed.The optimal synthesis processes of the product and its intermediates are obtained through experiments.1 The optimal synthesis process of 2,2-dichloro-3-dimethylamino-1,1,1-trifluoro-3-trimethylsilyloxypropane is as follows: the molar ratio of trimethyl chlorosilane, zinc powder, DMF to 1,1,1-trichlorotrifluoro ethane is 1.2:1.2:13:1; the reaction temperature is 5～10℃ and the reaction time is 2 h. With this process, the yield is about 60 % and the purity is about 90 %.