CONTROL OF ISOMER DISTRIBUTION IN A CHLORINATION PROCESS

摘要

The relative amounts of 5,6-dichloro-2-(trichloromethyl)pyridine and 3,6-dichloro-2-(trichloromethyl)pyridineobtained in the chlorination of2-chloro-6-(trichloromethyl)pyridine in the liquid phaseat temperatures of 160°C to 220°C and in the presence ofa metal halide catalyst, such as ferric chloride, arecontrolled by regulating the amount of hydrogen chloridepresent in the system, adding hydrogen chloride toobtain a mixture enriched in 5,6-dichloro-2-(triohloromethyl)pyridine or removing hydrogen chloride, usuallyby passing excess chlorine or an inert gas through thesystem, to obtain a mixture enriched in3,6-dichloro-2-(trichloromethyl)pyridine.