METHOD FOR PREPARING 2,3-DICHLORO-5-TRIFLUOROMETHYLPYRIDINE WITH HIGH SELECTIVITY

The present invention discloses a method for preparing 2,3-dichloro-5-trifluoromethylpyridine, comprising at a temperature of 100∼150°C and a pressure of 0.5∼5.0MP, in presence of at least one catalyst selected from supported metal chloride, supported zeolite molecular sieve and supported heteropolyacid, 2-chloro-5-trifluoromethylpyridine reacts with chlorine gas to obtain 2,3-dichloro-5-trifluoromethylpyridine. The preparing method provided by the present invention has advantages such as high selectivity of desired product, high utilization rate of chlorine gas, moderate process condition, simple operation and less three wastes. The present invention also discloses a preparing method for preparing 2-chloro-5-trifluoromethylpyridine, which is capable of reducing unit consumption, reducing separation cost, and improving safety compared to the prior art.