Process for recovering 2,3,5,6-tetrachloropyridine

A process for recovering 2,3,5,6-tetrachloropyridine from a first mixture containing initially 2,3,5,6-tetrachloropyridine, pentachloropyridine and at least one of 2,3,4,5-tetrachloropyridine and 2,3,4,6-tetrachloropyridine and no more than minor amounts, if any, of monochloropyridines, 3,5-dichloropyridine, 2,3,5-trichloropyridine and 2,3,6-trichloropyridine and no other chloropyridine compounds which comprises the steps of (a) reacting by contacting said first mixture of chlorinated pyridines at a temperature of from about 150.degree. C. to about 300.degree. C., in liquid phase, under atmospheric or superatmospheric pressure, with chlorine, in the presence of a small but catalytic amount of a Lewis acid catalyst whereby most of the 2,3,5,6-tetrachloropyridine does not undergo further chlorination while most if not all of the 2,3,4,5- and/or 2,3,4,6-tetrachloropyridine undergoes further chlorination to pentachloropyridine, to thereby obtain a second mixture of chlorinated pyridines consisting essentially of 2,3,5,6-tetrachloropyridine and pentachloropyridine, and (b) distilling said second mixture to recover the 2,3,5,6-tetrachloropyridine therefrom.