Chemistry:2-Chloropyridine
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.[1] It is one of three isomers of chloropyridine.
Preparation
2-Chloropyridine is produced by direct reaction of pyridine with chlorine. The initially formed 2-chloropyridine reacts further to give 2,6-dichloropyridine.[1]
Alternatively, 2-chloropyridines can be conveniently synthesized in high yields from pyridine-N-oxides.[2]
2-Chloropyridine was originally prepared by the chlorination of 2-hydroxypyridine with phosphoryl chloride.[3]
Main reactions and applications
2-Chloropyridine undergoes substitution at the C-Cl bond.[4][5] Some reactions using 2-chloropyridine generate mixtures of products.[1]
Some commercial products include pyrithione, pyripropoxyfen, chlorphenamine, and disopyramide. In these conversions, chloride is displaced.[1] Pyrithione, the conjugate base of 2-mercaptopyridine-N-oxide, is a fungicide found in some shampoos. Oxidation 2-chloropyridine gives 2-chloropyridine-N-oxide.[6] The antihistamine pheniramine may be generated via the reaction of phenylacetonitrile with 2-chloropyridine in the presence of a base.[7]
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.[8] Estimated time for complete degradation was > 30 days. 2-Chloropyridine exhibits extensive volatilization losses from water, less so when present in soil.[9]
Toxicity
The -1">50 is 64 mg/kg (dermal, rabbit).[1]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Shimizu, Shinkichi; Watanabe, Nanao; Kataoka, Toshiaki; Shoji, Takayuki; Abe, Nobuyuki; Morishita, Sinji; Ichimura, Hisao (2007). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_399.
- ↑ 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.
- ↑ 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. https://zenodo.org/record/2361968.
- ↑ Kevin W. C. Poon, Philip A. Albiniak, Gregory B. Dudley (2007). "Protection of Alcohols Using 2-Benzyloxy-1-Methylpyridinium Trifluoromethanesulfonate: Methyl (R)-(-)-3-Benzyloxy-2-Methyl Propanoate". Organic Syntheses 84: 295. doi:10.15227/orgsyn.084.0295.
- ↑ Patrick M. Pollock, Kevin P. Cole (2012). "t-Butyl as a Pyrazole Protecting Group: Preparation and Use of 1-tert-Butyl-3-Methyl-1H-Pyrazole-5-Amine". Organic Syntheses 89: 537. doi:10.15227/orgsyn.089.0537.
- ↑ 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
- ↑ Botteghi, Carlo; Chelucci, Giorgio; Del Ponte, Gino; Marchetti, Mauro; Paganelli, Stefano (1994). "New Synthetic Route to Pheniramines via Hydroformylation of Functionalyzed Olefins". The Journal of Organic Chemistry 59 (23): 7125–7127. doi:10.1021/jo00102a044.
- ↑ Sims, G. K. and L.E. Sommers. 1986. Biodegradation of pyridine derivatives in soil suspensions. Environmental Toxicology and Chemistry. 5:503-509.
- ↑ Sims, G. K. and L.E. Sommers. 1985. Degradation of pyridine derivatives in soil. Journal of Environmental Quality. 14:580-584.
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