3-Chloropyridine

3-Chloropyridine is an aryl chloride and isomer of chloropyridine with the formula C₅H₄ClN. It is a colorless liquid that is mainly used as a building block in organic synthesis.^[1]

3-Chloropyridine

Names
Preferred IUPAC name 3-Chloropyridine
Identifiers
CAS Number	626-60-8
3D model (JSmol)	Interactive image
ChemSpider	11784
ECHA InfoCard	100.009.960
EC Number	210-955-7
PubChem CID	12287
UNII	1M13HUC1P4
CompTox Dashboard (EPA)	DTXSID3052309
InChI InChI=1S/C5H4ClN/c6-5-2-1-3-7-4-5/h1-4H Key: PWRBCZZQRRPXAB-UHFFFAOYSA-N
SMILES C1=CC(=CN=C1)Cl
Properties
Chemical formula	C5H4ClN
Molar mass	113.54 g·mol−1
Appearance	colorless liquid
Density	1.194 g/cm3
Boiling point	148 °C (298 °F; 421 K)
Refractive index (nD)	1.533
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H226, H302, H312, H315, H332
Precautionary statements	P210, P233, P240, P241, P242, P243, P261, P264, P270, P271, P280, P301+P312, P302+P352, P303+P361+P353, P304+P312, P304+P340, P312, P321, P322, P330, P332+P313, P362, P363, P370+P378, P403+P235, P501
Flash point	65 °C (149 °F; 338 K)
Related compounds
Related compounds	2-Chloropyridine 3-Bromopyridine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The compound is a substrate for many coupling processes including the Heck reaction,^[2] Suzuki reaction,^[3] and Ullmann reaction.^[4]

Preparation

3-Chloropyridine may be prepared by the direct chlorination of pyridine with aluminium chloride used as the catalyst. The yield is 33%.^[5]

A less expensive way of preparing 3-chloropyridine consists of the gas phase pyrolysis of a mixture of pyrrole and chloroform in an empty glass tube. The molar ratio of the reagents is one to five. The yields range from 25 to 33%. A little 2-chloropyridine is formed as a side product.^[6] The process is thought to be an example of the Ciamician–Dennstedt rearrangement.

Pyrolytic Ciamician-Dennstedt rearrangement leading to 3-chloropyridine