This process can result in environmental and health problems. The metal is recovered from the 'pregnant solution' by reduction with zinc dust or by adsorption onto activated carbon. The 'pregnant liquor' containing these ions is separated from the solids, which are discarded to a tailing pond or spent heap, the recoverable gold having been removed. It undergoes hydrolysis to give ammonia and formate, which are far less toxic than cyanide: CN − + 2 H 2 O ⟶ HCO 2 − + NH 3 Thus, addition of acids stronger than hydrogen cyanide to solutions of cyanide salts releases hydrogen cyanide.Ĭyanide is unstable in water, but the reaction is slow until about 170 ☌. In inorganic chemistry, salts containing the −C≡N ion are referred to as cyanides.Ĭyanide is basic. Unlike nitriles, cyanohydridins do release hydrogen cyanide. A functional group with a hydroxyl –OH and cyanide –CN bonded to the same carbon atom is called cyanohydrin (C(–OH)(–CN)). Nitriles usually do not release cyanide ions.

An example of a nitrile is acetonitrile, CH 3−C≡N. In IUPAC nomenclature, organic compounds that have a –C≡N functional group are called nitriles. The biosynthesis of cyanide in the -hydrogenases proceeds from carbamoyl phosphate, which converts to cysteinyl thiocyanate, the CN − donor. The hydrogenase enzymes contain cyanide ligands attached to iron in their active sites. Certain plastics, especially those derived from acrylonitrile, release hydrogen cyanide when heated or burnt. For example, it can be detected in the exhaust of internal combustion engines and tobacco smoke. Hydrogen cyanide is produced by the combustion or pyrolysis of certain materials under oxygen-deficient conditions. Cyanogen, (CN) 2, is used to measure the temperature of interstellar gas clouds. CN has been identified in interstellar space.In response, the golden bamboo lemur, which eats the bamboo, has developed a high tolerance to cyanide. The Madagascar bamboo Cathariostachys madagascariensis produces cyanide as a deterrent to grazing. 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. In plants, cyanides are usually bound to sugar molecules in the form of cyanogenic glycosides and defend the plant against herbivores. Chemical compounds that can release cyanide are known as cyanogenic compounds. Cyanides are found in substantial amounts in certain seeds and fruit stones, e.g., those of bitter almonds, apricots, apples, and peaches. It is an antifeedant in a number of plants.

Removal of cyanide from cassava in Nigeria.Ĭyanides are produced by certain bacteria, fungi, and algae.

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