Cyanogen chloride

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Cyanogen chloride
Skeletal formula of cyanogen chloride
Preferred IUPAC name
Carbononitridic chloride
Systematic IUPAC name
Other names
  • Chlorine cyanide
  • Cyanic chloride
  • Chlorocyanogen
  • Chlorcyan
  • Chlorocyanide
506-77-4 YesY
Abbreviations CK
ChemSpider 10045 YesY
EC Number 208-052-8
Jmol 3D model Interactive image
MeSH cyanogen+chloride
PubChem 10477
RTECS number GT2275000
UN number 1589
Molar mass 61.470 g mol−1
Appearance Colorless gas
Odor acrid
Density 2.7683 mg mL−1 (at 0 °C, 101.325 kPa)
Melting point −6.55 °C (20.21 °F; 266.60 K)
Boiling point 13 °C (55 °F; 286 K)
Solubility soluble in ethanol, ether
Vapor pressure 1.987 MPa (at 21.1 °C)
236.33 J K−1 mol−1
137.95 kJ mol−1
Vapor pressure {{{value}}}
Related compounds
Related alkanenitriles
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cyanogen chloride is an inorganic compound with the formula NCCl. This linear, triatomic pseudohalogen is an easily condensed colorless gas. More commonly encountered in the laboratory is the related compound cyanogen bromide, a room-temperature solid that is widely used in biochemical analysis and preparation.

Synthesis, basic properties, structure

Cyanogen chloride is a molecule with the connectivity ClCN. Carbon and chlorine are linked by a single bond, and carbon and nitrogen by a triple bond. It is a linear molecule, as are the related cyanogen halides (NCF, NCBr, NCI). Cyanogen chloride is produced by the oxidation of sodium cyanide with chlorine. This reaction proceeds via the intermediate cyanogen ((CN)2).[2]

NaCN + Cl2 → ClCN + NaCl

The compound trimerizes in the presence of acid to the heterocycle called cyanuric chloride.

Cyanogen chloride is slowly hydrolyzed by water to release cyanate and chloride ions

ClCN + H2O → NCO- + Cl- + 2H+
at neutral pH

Applications in synthesis

Cyanogen chloride is a precursor to the sulfonyl cyanides[3] and chlorosulfonyl isocyanate, a useful reagent in organic synthesis.[4]


Also known as CK, cyanogen chloride is a highly toxic blood agent, and was once proposed for use in chemical warfare. It causes immediate injury upon contact with the eyes or respiratory organs. Symptoms of exposure may include drowsiness, rhinorrhea (runny nose), sore throat, coughing, confusion, nausea, vomiting, edema, loss of consciousness, convulsions, paralysis, and death.[5] It is especially dangerous because it is capable of penetrating the filters in gas masks, according to U.S. analysts. CK is unstable due to polymerization, sometimes with explosive violence.[6]

Cyanogen chloride is listed in schedule 3 of the Chemical Weapons Convention: all production must be reported to the OPCW.


  1. Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  2. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  3. Vrijland, M. S. A. (1977). "Sulfonyl Cyanides: Methanesulfonyl Cyanide" (PDF). Org. Synth. 57: 88.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>; Coll. Vol., 6, p. 727<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  4. Graf, R. (1966). "Chlorosulfonyl Isocyanate" (PDF). Org. Synth. 46: 23.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>; Coll. Vol., 5, p. 226<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  5. Cite error: Invalid <ref> tag; no text was provided for refs named niosh
  6. FM 3-8 Chemical Reference Handbook. US Army. 1967.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>

External links