Chloropyridine

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

Chloropyridines include:

• 2-Chloropyridine
• 3-Chloropyridine
• 4-Chloropyridine (used for ofornine & besipirdine).
• 2,6-Dichloropyridine

Direct halogenation of pyridine with chlorine gas above 270 °C gives a mixture of 2-chloropyridine and 2,6-dichloropyridine.^[1]

2- and 4-chloropyridine are prepared from the corresponding pyridinols using phosphoryl chloride.^[1]

Chloropyridines are important intermediates to pharmaceuticals and agrochemicals.^[1] A major use of 2-chloropyridine is the production of production of the fungicidepyrithione. Reaction of 4-chloropyridine with thioglycolic acid gives pyridylmercaptoacetic acid, a step in the production of cephalosporin antibiotics.

• Bromopyridine