2-Chloropyridine
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 477213072
| ImageFile = 2-chloropyridine.png
| ImageSize = 120px
| ImageFileL1 = 2-Chloropyridine Ball and Stick.png
| ImageSizeL1 = 130
| ImageFileR1 = 2-Chloropyridine Space Fill.png
| ImageSizeR1 = 120
| Name = 2-Chloropyridine
| PIN = 2-Chloropyridine
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 7689
| InChI = 1/C5H4ClN/c6-5-3-1-2-4-7-5/h1-4H
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 39174
| SMILES = Clc1ncccc1
| InChIKey = OKDGRDCXVWSXDC-UHFFFAOYAI
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 509579
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C5H4ClN/c6-5-3-1-2-4-7-5/h1-4H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = OKDGRDCXVWSXDC-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 109-09-1
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 8HMD45AYEJ
| PubChem = 7977
| EC_number = 203-646-3
| RTECS = US5950000
| UNNumber = 2822
| Beilstein = 105788
| Gmelin = 130818
}}
| Section2 = {{Chembox Properties
| Formula = C5H4ClN
| MolarMass = 113.54 g/mol
| Appearance = colorless liquid
| Density = 1.2 g/mL
| Solubility = 27 g/L
| MeltingPtC = -46
| BoilingPtC = 166
| pKa = 0.49 Linnell, R. H., J. Org. Chem., 1960, 25, 290.
}}
| Section7 = {{Chembox Hazards
| ExternalSDS = [http://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do MSDS]
| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS07}}{{GHS08}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|301|310|315|319|330|400}}
| PPhrases = {{P-phrases|260|261|262|264|270|271|273|280|284|301+310|301+312|302+350|302+352|304+340|305+351+338|310|311|312|314|320|321|322|330|332+313|337+313|361|362|363|391|403+233|405|501}}
| MainHazards =
}}
| Section8 = {{Chembox Related
| OtherCompounds = 3-Chloropyridine
3-Bromopyridine
2-Chloromethylpyridine
}}
}}
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.{{Ullmann|first1=Shinkichi|last1=Shimizu|first2=Nanao|last2= Watanabe|first3=Toshiaki|last3=Kataoka|first4=Takayuki|last4= Shoji|first5=Nobuyuki|last5=Abe|first6=Sinji|last6= Morishita|first7=Hisao|last7=Ichimura|title=Pyridine and Pyridine Derivatives|year=2007|doi=10.1002/14356007.a22_399}} 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.
Alternatively, 2-chloropyridines can be conveniently synthesized in high yields from pyridine-N-oxides.{{cite journal|doi=10.1081/SCC-120028642|title=Facile and Selective Synthesis of Chloromethylpyridines and Chloropyridines Using Diphosgene/Triphosgene|year=2004|last1=Narendar|first1=P.|last2=Gangadasu|first2=B.|last3=Ramesh|first3=Ch.|last4=China Raju|first4=B.|last5=Jayathirtha Rao|first5=V.|journal=Synthetic Communications|volume=34|issue=6|pages=1097–1103|s2cid=95706122}}
2-Chloropyridine was originally prepared by the chlorination of 2-hydroxypyridine with phosphoryl chloride.{{cite journal|doi=10.1002/cber.189102402155|title=Ueber das α-Pyridon (α-Oxypyridin)|year=1891|last1=Pechmann|first1=H. V.|last2=Baltzer|first2=O.|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=24|issue=2|pages=3144–3153|url=https://zenodo.org/record/2361968}}
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.
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. {{ISSN|1001-8255}} The antihistamine pheniramine may be generated via the reaction of phenylacetonitrile with 2-chloropyridine in the presence of a base.Botteghi, Carlo et al. New Synthetic Route to Pheniramines via Hydroformylation of Functionalyzed Olefins. 1994, 59, pp. 7125-7127. {{doi|10.1021/jo00102a044}}
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 LD50 is 64 mg/kg (dermal, rabbit).
References
{{reflist}}
{{DEFAULTSORT:Chloropyridine, 2-}}