Cyanide

[2] Hydrocyanic acid, also known as hydrogen cyanide, or HCN, is a highly volatile liquid that is produced on a large scale industrially.A triple bond exists between C and N. The negative charge is concentrated on carbon C.[3][4] Cyanides are produced by certain bacteria, fungi, and algae.Cyanides are found in substantial amounts in certain seeds and fruit stones, e.g., those of bitter almonds, apricots, apples, and peaches.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 biosynthesis of cyanide in the NiFe hydrogenases proceeds from carbamoyl phosphate, which converts to cysteinyl thiocyanate, the CN− donor.A functional group with a hydroxyl −OH and cyanide −CN bonded to the same carbon atom is called cyanohydrin (R2C(OH)CN).[19] The high affinities of metals for this anion can be attributed to its negative charge, compactness, and ability to engage in π-bonding.The cyanide anion is an inhibitor of the enzyme cytochrome c oxidase (also known as aa3), the fourth complex of the electron transport chain found in the inner membrane of the mitochondria of eukaryotic cells.As a result, the electron transport chain is disrupted, meaning that the cell can no longer aerobically produce ATP for energy.For this reason, working with hydrogen cyanide requires wearing an air respirator supplied by an external oxygen source.The major mechanism to remove the cyanide from the body is by enzymatic conversion to thiocyanate by the mitochondrial enzyme rhodanese.To accelerate this detoxification, sodium thiosulfate is administered to provide a sulfur donor for rhodanese, needed in order to produce thiocyanate.[28] Cyanide is mainly produced for the mining of silver and gold: It helps dissolve these metals allowing separation from the other solids.Instead, a displacement reaction occurs: 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.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.During World War I, a copper cyanide compound was briefly used by Japanese physicians for the treatment of tuberculosis and leprosy.[35] Cyanide is also used for pest control in New Zealand, particularly for possums, an introduced marsupial that threatens the conservation of native species and spreads tuberculosis amongst cattle.[48] Iron(II) sulfate added to a solution of cyanide, such as the filtrate from the sodium fusion test, gives prussian blue.