Method for preparing 2-chloro-5-trifluoromethylpyridine

Abstract

The present invention provides a method for the preparing of 2-chloro-5-trifluoromethylpyridine, comprising two steps of chlorofluorination reaction and chlorination reaction, the chlorination catalyst used in the chlorination reaction was chosen from a fluoride, an oxide, a hydroxide, a carbonate, or a chloride of magnesium, calcium and barium and a supported palladium catalyst; or under the action of at least one catalyst chosen from ZSM-5, 5A, β and 13× molecular sieves, 3-trifluoromethylpyridine and chlorine gas phase have reaction to obtain 2-chloro-5-trifluoromethylpyridine. Or, under the action of a catalyst chosen from a fluoride, an oxide, a hydroxide, a carbonate, or a chloride of magnesium, calcium, and barium and a supported palladium catalyst, 3-trifluoromethylpyridine and chlorine gas phase have reaction to obtain 2-chloro-5-trifluoromethylpyridine. The present invention has the advantages of easily availability and low-cost of raw materials, safe operation, high yield, easy isolation and recovery of catalyst, environmental protection, fast reaction speed and continuous production on a large-scale, etc.