Selective gas phases - chlorination of polychlorinated beta - picolines for the production of 2,3,5,6 - tetra chlorine pyridine, as well as its precursors

摘要

2,3,5,6-Tetrachloropyridine, and 2,3-dichloro-5- (trichloromethyl) pyridine are prepared by selectively chlorinating polychlorinated &bgr;- picolines in the vapor phase between about 250° and 450° C. in the presence of specific Lewis acid halide catalysts on an inorganic support. The gamma position on the pyridine ring is usually not chlorinated in the starting material or reaction products. These compounds are useful intermediates to produce insecticides and herbicides.