2-chloropyridine

2-Chloropyridine

2-Chloropyridine

Chemical compound

2-Chloropyridine is an aryl chloride with the formula C5H4ClN. 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.[2] It is one of three isomers of chloropyridine.

Quick Facts Names, Identifiers ...

Preparation

2-Chloropyridine is produced by direct reaction of pyridine with chlorine. The initially formed 2-chloropyridine reacts further to give 2,6-dichloropyridine.[2]

Alternatively, 2-chloropyridines can be conveniently synthesized in high yields from pyridine-N-oxides.[3]

2-Chloropyridine was originally prepared by the chlorination of 2-hydroxypyridine with phosphoryl chloride.[4]

Main reactions and applications

2-Chloropyridine reacts with nucleophiles to generate pyridine derivatives substituted at the second and fourth carbons on the heterocycle. Therefore, many reactions using 2-chloropyridine generate mixtures of products which require further workup to isolate the desired isomer.[2]

Some commercial products include pyrithione, pyripropoxyfen, chlorphenamine, and disopyramide. In these conversions, chloride is displaced.[2] Pyrithione, the conjugate base of 2-mercaptopyridine-N-oxide, is a fungicide found in some shampoos. Oxidation 2-chloropyridine gives 2-chloropyridine-N-oxide.[5] The antihistamine pheniramine may be generated via the reaction of phenylacetonitrile with 2-chloropyridine in the presence of a base.[6]

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.[7] Estimated time for complete degradation was > 30 days. 2-Chloropyridine exhibits extensive volatilization losses from water, less so when present in soil.[8]

Toxicity

The LD50 is 64 mg/kg (dermal, rabbit).[2]

References

  1. [1]
    Linnell, R. H., J. Org. Chem., 1960, 25, 290.
  2. [2]
    Shimizu, Shinkichi; Watanabe, Nanao; Kataoka, Toshiaki; Shoji, Takayuki; Abe, Nobuyuki; Morishita, Sinji; Ichimura, Hisao (2007). "Pyridine and Pyridine Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_399. ISBN 978-3527306732.
  3. [3]
    Narendar, P.; Gangadasu, B.; Ramesh, Ch.; China Raju, B.; Jayathirtha Rao, V. (2004). "Facile and Selective Synthesis of Chloromethylpyridines and Chloropyridines Using Diphosgene/Triphosgene". Synthetic Communications. 34 (6): 1097–1103. doi:10.1081/SCC-120028642. S2CID 95706122.
  4. [4]
    Pechmann, H. V.; Baltzer, O. (1891). "Ueber das α-Pyridon (α-Oxypyridin)". Berichte der Deutschen Chemischen Gesellschaft. 24 (2): 3144–3153. doi:10.1002/cber.189102402155.
  5. [5]
    Cheng, Hefeng; She, Ji. 14. Improved preparation of 2-mercaptopyridine-N-oxide. Zhongguo Yiyao Gongye Zazhi. 1990, 21, (2), pp. 55-56. ISSN 1001-8255
  6. [6]
    Botteghi, Carlo et al. New Synthetic Route to Pheniramines via Hydroformylation of Functionalyzed Olefins. 1994, 59, pp. 7125-7127. doi:10.1021/jo00102a044
  7. [7]
    Sims, G. K. and L.E. Sommers. 1986. Biodegradation of pyridine derivatives in soil suspensions. Environmental Toxicology and Chemistry. 5:503-509.
  8. [8]
    Sims, G. K. and L.E. Sommers. 1985. Degradation of pyridine derivatives in soil. Journal of Environmental Quality. 14:580-584.
Share this article:

This article uses material from the Wikipedia article 2-chloropyridine, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.