Chloropyridine

Chloropyridines are a group of aryl chlorides consisting of a pyridine ring with chlorine atoms as substituents.
Chloropyridines include:

Production

Direct halogenation of pyridine with chlorine gas above 270 °C gives a mixture of 2-chloropyridine and 2,6-dichloropyridine.
2- and 4-chloropyridine are prepared from the corresponding pyridinols using phosphoryl chloride.

Uses

Chloropyridines are important intermediates to pharmaceuticals and agrochemicals. A major use of 2-chloropyridine is the production of production of the fungicide pyrithione. Reaction of 4-chloropyridine with thioglycolic acid gives pyridylmercaptoacetic acid, a step in the production of cephalosporin antibiotics.