Cyanogen chloride

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Cyanogen chloride

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Template:Longitem	Template:Unbulleted list
Abbreviations	CK
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MeSH	cyanogen+chloride
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UN number	1589
Template:Longitem	ClCN
Molar mass	61.470 g/mol
Appearance	Colorless gas
Odor	acrid
Density	2.7683 mg/cm3 (at 0 °C, 101.325 kPa)
Melting point	Template:Chembox CalcTemperatures
Boiling point	Template:Chembox CalcTemperatures
Solubility	soluble in ethanol, ether
Vapor pressure	1.987 MPa (at 21.1 °C)
Template:Longitem	−32.4·10−6 cm3/mol
Template:Longitem	236.33 J/(mol·K)
Template:Longitem	137.95 kJ/mol
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Cyanogen chloride is an inorganic compound with the formula Template:Chem2. This 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 used in biochemical analysis and preparation. Cyanogen compounds are highly toxic.

Synthesis, basic properties, structure

Cyanogen chloride is a linear molecule with the connectivity Template:Chem2, as are HCN and the related cyanogen halides (FCN, BrCN, ICN). The carbon and chlorine atoms are linked by a single bond, and carbon and nitrogen by a triple bond. It is a linear molecule. Cyanogen chloride is produced by the oxidation of sodium cyanide with chlorine. This reaction proceeds via the intermediate cyanogen (Template:Chem2).

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

Cyanogen chloride is slowly hydrolyzed by water at neutral pH to release cyanate and chloride ions:

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Applications in synthesis

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

Further chlorination gives the isocyanide dichloride.

Safety

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. It is especially dangerous because it is capable of penetrating the filters in gas masks, according to United States analysts. CK is unstable due to polymerization, sometimes with explosive violence.

Chemical weapon

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

By 1945, the U.S. Army's Chemical Warfare Service developed chemical warfare rockets intended for the new M9 and M9A1 Bazookas. An M26 Gas Rocket was adapted to fire cyanogen chloride-filled warheads for these rocket launchers. As it was capable of penetrating the protective filter barriers in some gas masks, it was seen as an effective agent against Japanese forces (particularly those hiding in caves or bunkers) because their standard issue gas masks lacked the barriers that would provide protection against cyanogen chloride. The US added the weapon to its arsenal, and considered using it, along with hydrogen cyanide, as part of Operation Downfall, the planned invasion of Japan, but President Harry Truman decided against it, instead using the atomic bombs developed by the secret Manhattan Project. The CK rocket was never deployed or issued to combat personnel.