A Cyanide is a chemical compound that contains the group C≡N. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.
In inorganic cyanides, the cyanide group is present as the anion CN−. Salts such as sodium cyanide and potassium cyanide are highly toxic. Hydrocyanic acid, also known as hydrogen cyanide, or HCN, is a highly volatile liquid that is produced on a large scale industrially. It is obtained by acidification of cyanide salts.
Organic cyanides are usually called nitriles. In nitriles, the CN group is linked by a covalent bond to carbon. For example, in acetonitrile, the cyanide group is bonded to methyl (CH3). Because they do not release cyanide ions, nitriles are generally far less toxic than cyanide salts. Some nitriles, which occur naturally as cyanohydrins, release hydrogen cyanide.
The cyanide compound sodium nitroprusside is used mainly in clinical chemistry to measure urine ketone bodies mainly as a follow-up to diabetic patients. On occasion, it is used in emergency medical situations to produce a rapid decrease in blood pressure in humans; it is also used as a vasodilator in vascular research. The cobalt in artificial vitamin B12 contains a cyanide ligand as an artifact of the purification process; this must be removed by the body before the vitamin molecule can be activated for biochemical use. During World War I, a copper cyanide compound was briefly used by Japanese physicians for the treatment of tuberculosis and leprosy.