The invention discloses a 2,3,5,6-tetrachloropyridine synthesis and
separation method, which comprises the following operation steps: (1) introducing gasified
pyridine and
chlorine into a primary chlorination reactor to prepare 2-chloropyridine and 2,6-dichloropyridine; (2) gasifying 2-chloropyridine and 2,6-dichloropyridine by heating to prepare 2,3,6-trichloropyridine and 2,3,5-trichloropyridine; (3) gasifying the liquid-phase 2,3,6-trichloropyridine and 2,3,5-trichloropyridine, introducing products into a high-grade chlorination reactor, introducing excessive
chlorine, continuously distilling to obtain tetrachloropyridine in a crude product
tower and pentachloropyridine at the
tower bottom; (4) adding pentachloropyridine into a
high pressure reactor, adding
zinc dust and 31% industrialhydrochloric acid to obtain 2,3,5,6-tetrachloropyridine; and (5) letting the tetrachloropyridine obtained after
distillation in the crude product
tower undergo electrolytic reaction to prepare the 2,3,5,6-tetrachloropyridine. The 2,3,5,6-tetrachloropyridine synthesis and
separation method provided by the invention has the following advantages:
utilization rate of the raw materials is high, productpurity is high, the process is simple, and the environmental
pollution is low.