Cyanogen chloride

Cyanogen chloride is a toxic chemical 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.

Cyanogen chloride
Skeletal formula of cyanogen chloride
Ball and stick model of cyanogen chloride
Spacefill model of cyanogen chloride
Preferred IUPAC name
Carbononitridic chloride
Systematic IUPAC name
Other names
  • Chlorine cyanide
  • Cyanic chloride
  • Chlorocyanogen
  • Chlorcyan
  • Chlorocyanide
3D model (JSmol)
Abbreviations CK
ECHA InfoCard 100.007.321
EC Number 208-052-8
MeSH cyanogen+chloride
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)
-32.4·10−6 cm3/mol
236.33 J K−1 mol−1
137.95 kJ mol−1
Main hazards Highly toxic;[2] forms cyanide in the body[3]
Safety data sheet
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 4: Very short exposure could cause death or major residual injury. E.g., VX gasReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorusSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point nonflammable [3]
US health exposure limits (NIOSH):
PEL (Permissible)
REL (Recommended)
C 0.3 ppm (0.6 mg/m3)[3]
IDLH (Immediate danger)
Related compounds
Related alkanenitriles
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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).[4]

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[5] and chlorosulfonyl isocyanate, a useful reagent in organic synthesis.[6]


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.[2] 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.[7]

Chemical weapon

Cyanogen chloride is listed in schedule 3 of the Chemical Weapons Convention: all production must be reported to the OPCW.[8]

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.[9] As it was capable of penetrating the protective filter barriers in some gas masks,[10] it was seen as an effective agent against Japanese forces (particularly those hiding in caves or bunkers) because their standard issues gas masks lacked the barriers that would provide protection against cyanogen chloride.[9][11][12] The US added the weapon to its arsenal but the CK rocket was never deployed or issued to combat personnel.[9]


  1. ^ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.
  2. ^ a b "CYANOGEN CHLORIDE (CK)". The Emergency Response Safety and Health Database. NIOSH.
  3. ^ a b c d e "NIOSH Pocket Guide to Chemical Hazards #0162". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ Coleman, G. H.; Leeper, R. W.; Schulze, C. C. (1946). "Cyanogen Chloride". Inorganic Syntheses. 2: 90–94. doi:10.1002/9780470132333.ch25.
  5. ^ Vrijland, M. S. A. (1977). "Sulfonyl Cyanides: Methanesulfonyl Cyanide" (PDF). Organic Syntheses. 57: 88.; Collective Volume, 6, p. 727
  6. ^ Graf, R. (1966). "Chlorosulfonyl Isocyanate" (PDF). Organic Syntheses. 46: 23.; Collective Volume, 5, p. 226
  7. ^ FM 3-8 Chemical Reference Handbook. US Army. 1967.
  8. ^ "Schedule 3". Retrieved 16 March 2018.
  9. ^ a b c Smart, Jeffrey (1997), "2", History of Chemical and Biological Warfare: An American Perspective, Aberdeen, MD, USA: Army Chemical and Biological Defense Command, p. 32.
  10. ^
  11. ^ "Characteristics and Employment of Ground Chemical Munitions", Field Manual 3-5, Washington, DC: War Department, 1946, pp. 108–19.
  12. ^ Skates, John R (2000), The Invasion of Japan: Alternative to the Bomb, University of South Carolina Press, pp. 93–96, ISBN 978-1-57003-354-4

External links


Acetonitrile is the chemical compound with the formula CH3CN. This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not classed as organic). It is produced mainly as a byproduct of acrylonitrile manufacture. It is used as a polar aprotic solvent in organic synthesis and in the purification of butadiene.In the laboratory, it is used as a medium-polarity solvent that is miscible with water and a range of organic solvents, but not saturated hydrocarbons. It has a convenient liquid range and a high dielectric constant of 38.8. With a dipole moment of 3.92 D, acetonitrile dissolves a wide range of ionic and nonpolar compounds and is useful as a mobile phase in HPLC and LC–MS. The N≡C−C skeleton is linear with a short C≡N distance of 1.16 Å.Acetonitrile was first prepared in 1847 by the French chemist Jean-Baptiste Dumas.


Aminoacetonitrile is a simple organic compound containing both nitrile and amino groups. It is somewhat similar to the simplest amino acid, glycine. This compound is commercially available as the chloride and sulfate salts.

Blood agent

A blood agent is a toxic chemical agent that affects the body by being absorbed into the blood. Blood agents are fast-acting, potentially lethal poisons that typically manifest at room temperature as volatile colorless gases with a faint odor. They are either cyanide- or arsenic-based.

Compounds of carbon

Compounds of carbon are defined as chemical substances containing carbon. More compounds of carbon exist than any other chemical element except for hydrogen. Organic carbon compounds are far more numerous than inorganic carbon compounds. In general bonds of carbon with other elements are covalent bonds. Carbon is tetravalent but carbon free radicals and carbenes occur as short-lived intermediates. Ions of carbon are carbocations and carbanions are also short-lived. An important carbon property is catenation as the ability to form long carbon chains and rings.

Cyanogen azide

Cyanogen azide, N3CN or CN4, is an azide compound of carbon and nitrogen which is an oily, colourless liquid at room temperature. It is a highly explosive chemical that is soluble in most organic solvents, and normally handled in dilute solution in this form. It was first synthesised by F.D. Marsh at DuPont in the early 1960s.Extremely dangerous outside dilute solution, cyanogen azide has nonetheless been prepared in situ for use in the synthesis of chemicals such as diaminotetrazoles. It can be synthesised at below room temperature from the reaction of sodium azide with either cyanogen chloride or cyanogen bromide, dissolved in a solvent such as acetonitrile; this reaction must be done with care due to the production from trace moisture of shock-sensitive byproducts.

Cyanogen halide

A cyanogen halide is a molecule consisting of cyanide and a halogen. Cyanogen halides are chemically classified as pseudohalogens.

The cyanogen halides are a group of chemically reactive compounds which contain a cyano group (-CN) attached to a halogen element, such as fluorine, chlorine, bromine or iodine. Cyanogen halides are colorless, volatile, lacrimatory (tear-producing) and highly poisonous compounds.

Cyanuric chloride

Cyanuric chloride is an organic compound with the formula (NCCl)3. This white solid is the chlorinated derivative of 1,3,5-triazine. It is the trimer of cyanogen chloride. Cyanuric chloride is the main precursor to the popular but controversial herbicide atrazine.

François Stanislas Cloez

François Stanislas Cloez (24 June 1817 – 12 October 1883) was a French chemist, who authored both as "F. S. Cloez" and "S. Cloez", and is known for his pioneering role in analytical chemistry during the 19th century. He was a founder and later president of the Chemistry Society of France.In 1851, Cloez and Italian chemist Stanislao Cannizzaro, working on collaborative research, prepared cyanamide by the action of ammonia on cyanogen chloride in ethereal solution.

In the 1870s, he commenced the identification of the constituents of individual essential oils and their classification into groups according to their suitability for medicinal, industrial and perfumery purposes. He identified the major constituent of eucalyptus oil, which he called "eucalyptol" (now generally known as cineole). In honour of his work on eucalyptus oil Eucalyptus cloeziana (Gympie messmate) is named after him.Cloez also played a role in developing a theory on the origin of life elsewhere in the Solar system.In 1864, Cloez was the first scientist to examine a carbonaceous chondrite, the Orgueil meteorite, after it had fallen in France. Cloez said that its content "would seem to indicate the existence of organized substances in celestial bodies."

The Orgueil meteorite was subject to a hoax, when a sample of the meteorite was contaminated with a rush seed. The hoax was discovered in the 1960s when the meteorite was being examined for evidence of extraterrestrial biological material. There is no suggestion in literature that Cloez was party to this hoax.


Glycolonitrile, also called hydroxyacetonitrile or formaldehyde cyanohydrin, is the organic compound with the formula HOCH2CN. It is the simplest cyanohydrin and it is derived from formaldehyde. It is a colourless liquid that dissolves in water and ether. Because glycolonitrile decomposes readily into formaldehyde and hydrogen cyanide, it is listed as an extremely hazardous substance. In January 2019, astronomers reported the detection of glycolonitrile, another possible building block of life among other such molecules, in outer space.

Isla San José (Panama)

Isla San José is the second largest island in the Pearl Islands, and has an area of 44 km². At the 2000 census, it had a population of 10. The privately owned island has an area of about 17 square miles. Thousands of wild pigs and deer populate Isla San Jose, which has a rugged, rocky shoreline and over 50 beaches.A unit of U.S. soldiers tested chemical arms from 1945 to 1947 on the then deserted island, leaving behind at least eight unexploded 500 and 1,000-pound bombs. A U.S. military text states that the larger bombs contained phosgene and cyanogen chloride, and smaller ones mustard gas. Other reports state that the soldiers also tested VX nerve gas and sarin. Claims of abandoned mine fields containing thousands of armed chemical mines have been made, but no evidence of this has been presented. An unknown but large amount of munitions was also dropped into the sea around the island.The island is served by San José Airport.

List of UN numbers 1501 to 1600

The UN numbers from UN1501 to UN1600 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods.

Namhung Youth Chemical Complex

The Namhŭng Youth Chemical Complex is a large industrial complex in Namhŭng-dong, Anju-si, South P'yŏngan province, North Korea, and is one of the most important chemical factories in the country, being a major producer of chemical products such as fertilisers, herbicides, insecticides, various industrial chemicals. various plastics such as polyethylene sheeting, and various synthetic textiles. It is also believed to produce chemical weapons such as cyanogen chloride and mustard gas.The complex was originally built in 1976 with French, Japanese and West German equipment, initially producing ammonia by naphtha gasification, acrylic and polycarbonate fibres, and urea fertiliser, using naphtha brought in from the Sŭngri and Ponghwa chemical factories. In 2000, new equipment was installed to produce sodium carbonate, and renovations of the complex began in 2006. Also in 2006, the construction of a new anthracite gasification plant began; this was opened in 2010, and its output is being used to produce fertiliser, and by 2011 a second gasification plant was opened.The facility is served by the Korean State Railway via Namhŭng station on the Namhŭng Line. It also has its own fleet of shunting locomotives, along with facilities for the maintenance of rail equipment.

Nettle agent

Nettle agents or urticants are a variety of chemical warfare agents that produce corrosive skin and tissue injury upon contact, resulting in erythema, urticaria, intense itching, and a hive-like rash.Most nettle agents, such as the best known and studied nettle agent, phosgene oxime, are often grouped with the vesicant (blister agent) chemical agents. However, because nettle agents do not cause blisters, they are not true vesicants.

Proton affinity (data page)

Proton affinities are quoted in kJ/mol, in increasing order of gas-phase basicity of the base.

Source: Jolly, William L. (1991). Modern Inorganic Chemistry (2nd Edn.). New York: McGraw-Hill. ISBN 0-07-112651-1.

Pulmonary agent

A pulmonary agent, or choking agent, is a chemical weapon agent designed to impede a victim's ability to breathe. They operate by causing a build-up of fluids in the lungs, which then leads to suffocation. Exposure to the eyes and skin tends to be corrosive, causing blurred vision and severe deep burns. Inhalation of these agents cause burning of the throat, coughing, vomiting, headache, pain in chest, tightness in chest, and respiratory and circulatory failure.

Examples of pulmonary agents include:

Chlorine gas

Chloropicrin (PS)

Diphosgene (DP)

Phosgene (CG)

Disulfur decafluoride



DiphenylcyanoarsinePhosgene is the most dangerous commonly used pulmonary agent (although disulfur decafluoride and perfluoroisobutene are both even more dangerous, with respectively 4 and 10 times the lethality of phosgene, neither is widely used). It is a colorless gas under ordinary conditions. It has a vapor density 3.4 times greater than that of air, allowing it to remain low in the air for long periods of times. Phosgene leads to massive pulmonary edema, which reaches maximum symptoms in 12 hours after exposure, followed by death within 24 to 48 hours.

Chlorine is an element used in industry. It is one of the most commonly manufactured chemicals in the United States. It is used to make pesticides, rubber, and solvents. It is also used in drinking water and swimming pools to kill bacteria. The extent of poisoning chlorine causes depends on the amount of chlorine to which a person is exposed.

Tabun (nerve agent)

Tabun or GA is an extremely toxic chemical substance. It is a clear, colorless, and tasteless liquid with a faint fruity odor. It is classified as a nerve agent because it fatally interferes with normal functioning of the mammalian nervous system. Its production is strictly controlled and stockpiling outlawed by the Chemical Weapons Convention of 1993. Tabun is the first of the G-series nerve agents along with GB (sarin), GD (soman) and GF (cyclosarin).

Although pure tabun is clear, less-pure tabun may be brown. It is a volatile chemical, although less so than either sarin or soman.Tabun can be destroyed with bleaching powder (calcium hypochlorite), though the poisonous gas cyanogen chloride is produced.EA-4352 is an isopropyl analog to Tabun.

Trimer (chemistry)

In chemistry, a trimer is a molecule or an anion formed by combination or association of three molecules or ions of the same substance. In technical jargon, a trimer is a kind of oligomer derived from three identical precursors often in competition with polymerization.

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