Cyanide

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. In IUPAC nomenclature, organic compounds that have a –C≡N functional group are called nitriles. Thus, nitriles are organic compounds.An example of a nitrile is CH3CN, acetonitrile, also known as methyl cyanide. Nitriles usually do not release cyanide ions. A functional group with a hydroxyl and cyanide bonded to the same carbon is called cyanohydrin. Unlike nitriles, cyanohydridins do release hydrogen cyanide. In inorganic chemistry, salts containing the C≡N− ion are referred to as cyanides. The word is derived from the Greek kyanos, meaning dark blue, as a result of its being first obtained by the heating of the pigment known as Prussian blue. The cyanide ion is isoelectronic with carbon monoxide and with molecular nitrogen. Cyanides are produced by certain bacteria, fungi, and algae and are found in a number of plants. Cyanides are found in substantial amounts in certain seeds and fruit stones, e.g., those of bitter almonds, apricots, apples, and peaches. Chemical compounds that can release cyanide are known as cyanogenic compounds. In plants, cyanides are usually bound to sugar molecules in the form of cyanogenic glycosides and defend the plant against herbivores. Cassava roots (also called manioc), an important potato-like food grown in tropical countries (and the base from which tapioca is made), also contain cyanogenic glycosides. The Madagascar bamboo Cathariostachys madagascariensis produces cyanide as a deterrent to grazing. In response, the golden bamboo lemur, which eats the bamboo, has developed a high tolerance to cyanide.