2-Chloropyridine is an organic compound with the fomula ClC5H4N. It is a colorless liquid that is mainly used to generate fungicides and insecticides in industry. It also serves to generate antihistamines and antiarrythymics for pharmaceutical purposes. It is one of three isomers of chloropyridine.
Preparation
2-Chloropyridine is produced by direct reaction of pyridine with chlorine.
Alternatively, 2-chloropyridines can be conveniently synthesized in high yields from pyridine-N-oxides.
2-Chloropyridine was originally prepared by the chlorination of 2-hydroxypyridine with phosphoryl chloride.
Main reactions and applications 2-Chloropyridine reacts further with chlorine to give 2,6-dichloropyridine.
2-Chloropyridine undergoes substitution at the C-Cl bond.
Some commercial products include pyrithione, pyripropoxyfen, chlorphenamine, and disopyramide. In these conversions, chloride is displaced. Pyrithione, the conjugate base of 2-mercaptopyridine-N-oxide, is a fungicide found in some shampoos. Oxidation 2-chloropyridine gives 2-chloropyridine-N-oxide.Cheng, Hefeng; She, Ji. 14. Improved preparation of 2-mercaptopyridine-N-oxide. Zhongguo Yiyao Gongye Zazhi. 1990, 21, (2), pp. 55-56. The antihistamine pheniramine may be generated via the reaction of phenylacetonitrile with 2-chloropyridine in the presence of a base.
Environmental properties Although pyridine is an excellent source of carbon, nitrogen, and energy for certain microorganisms, introduction of a halogen moiety significantly retards degradation of the pyridine ring. With the exception of 4-chloropyridine, each of the mono- and di-substituted chloropyridines were found to be relatively resistant to microbiological degradation in soil or liquid media.Sims, G. K. and L.E. Sommers. 1986. Biodegradation of pyridine derivatives in soil suspensions. Environmental Toxicology and Chemistry. 5:503-509. Estimated time for complete degradation was > 30 days. 2-Chloropyridine exhibits extensive volatilization losses from water, less so when present in soil.Sims, G. K. and L.E. Sommers. 1985. Degradation of pyridine derivatives in soil. Journal of Environmental Quality. 14:580-584.
Toxicity The is 64 mg/kg (dermal, rabbit).
References