Method for preparing 2,6-dichloropyridine by pyridine liquid-phase photochlorination

The invention relates to a method for preparing 2,6-dichloropyridine with product purity greater than or equal to 99.0% by using chlorotrifluoromethylbenzene as a solvent for a reaction between pyridine and chlorine. The preparing process comprises the steps as follows: by using the pyridine and the chlorine as initial raw materials and using the chlorotrifluoromethylbenzene as the solvent, continuously performing a chlorination reaction on the pyridine and the chlorine under the irradiation of ultraviolet light; and cooling a chlorination reaction product and the solvent to obtain pyridine chloride solution. The method has the advantages that 1, a precedent of directly preparing the 2,6-dichloropyridine in a high selectivity mode by a liquid-phase photochlorination reaction is set, and not only is the 2,6-dichloropyridine product with purity greater than or equal to 99.0% obtained, but also the method is easy for industrial production; and 2, not only is recycling of the separation solvent in the preparing p