Abstract: A preparative high performance liquid chromatographic technique was used to separate and purify 2-chloro-5-trichloromethylpyridine from the products of photochemical chlorination with 3-methylpyridine as raw material. The elution mode, the flow rate of the mobile phase and injection volume were optimized. The optimum operation parameters were selected as follows: Zorbox-C18 reversed-phase column with the flow rate gradient elution of 30% acetonitrile in water as the mobile phase (gradient elution program: 0-8 min at 4 mL/min, 8-14 min at 10 mL/min), and a diode array detector with wavelength set at 240 nm, injecting volume of 100 μL. The average recovery rate was 82.7% and relative standard deviation (RSD) was 4.0%（n=5）. High purity (99.01%) product was obtained. The effective and accurate method has been successfully applied to the preparation of pure 2-chloro-5-trichloromethylpyridine.

Key words: 2-chloro-5-trichloromethylpyridine, 3-methylpyridine, flow-rate gradient elution, photochemical chlorination product , preparative liquid chromatography