Editing Cyanide (section)

==Occurrence==

===In nature===
[[File:Removal of cyanide poison from cassava.jpg|thumb|left|Removal of cyanide from [[cassava]] in [[Nigeria]]]]
Cyanides are produced by certain [[bacterium|bacteria]], [[fungi]], and [[algae]]. It is an [[antifeedant]] in a number of plants. Cyanides are found in substantial amounts in certain seeds and fruit stones, e.g., those of [[bitter almond]]s, [[apricot]]s, [[apple]]s, and [[peach]]es.<ref>{{Cite web|url=https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsLanding.aspx?id=71&tid=19 |title=ToxFAQs for Cyanide |access-date=2008-06-28 |date = July 2006|publisher=[[Agency for Toxic Substances and Disease Registry]]}}</ref> 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 [[glycoside]]s and defend the plant against [[herbivore]]s. [[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.<ref>{{Cite journal|first=J. |last=Vetter |title=Plant cyanogenic glycosides |journal=Toxicon |year=2000 |volume=38 |pages=11–36 |doi=10.1016/S0041-0101(99)00128-2 |pmid=10669009 |issue=1|bibcode=2000Txcn...38...11V}}</ref><ref name=jones>{{Cite journal|first=D. A. |last=Jones |title= Why are so many food plants cyanogenic? |journal=[[Phytochemistry (journal)|Phytochemistry]] |year=1998 |volume=47 |pages=155–162 |doi=10.1016/S0031-9422(97)00425-1 |pmid=9431670 |issue=2|bibcode=1998PChem..47..155J}}</ref>

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.

The [[hydrogenase]] enzymes contain cyanide [[ligand]]s attached to iron in their active sites. The biosynthesis of cyanide in the [[NiFe hydrogenase]]s proceeds from [[carbamoyl phosphate]], which converts to [[cystein]]yl [[thiocyanate]], the {{chem2|CN−}} donor.<ref>{{cite journal |last1=Reissmann |first1=Stefanie |last2=Hochleitner |first2=Elisabeth |last3=Wang |first3=Haofan |last4=Paschos |first4=Athanasios |last5=Lottspeich |first5=Friedrich |last6=Glass |first6=Richard S. |last7=Böck |first7=August |title=Taming of a Poison: Biosynthesis of the NiFe-Hydrogenase Cyanide Ligands |journal=Science |volume=299 |issue=5609 |pages=1067–1070 |year=2003 |pmid=12586941 |doi=10.1126/science.1080972 |bibcode=2003Sci...299.1067R |s2cid=20488694 |url=http://pdfs.semanticscholar.org/d359/5a5928df6c6209f88e105c937ccce0a05237.pdf |archive-url=https://web.archive.org/web/20201123134841/http://pdfs.semanticscholar.org/d359/5a5928df6c6209f88e105c937ccce0a05237.pdf |archive-date=2020-11-23 |url-status=live}}</ref>

===Interstellar medium===
The [[cyanide radical]] <sup>•</sup>CN has been identified in [[interstellar space]].<ref>{{Cite journal |last=Pieniazek |first=Piotr A. |author2=Bradforth, Stephen E. |author3=Krylov, Anna I. |title=Spectroscopy of the Cyano Radical in an Aqueous Environment |date=2005-12-07 |pages=4854–4865 |issue=14 |volume=110 |url=http://www-bcf.usc.edu/~krylov/pubs/pdf/jpca-110-4854.pdf |journal=The Journal of Physical Chemistry A |pmid=16599455 |doi=10.1021/jp0545952 |bibcode=2006JPCA..110.4854P |access-date=2008-08-23 |archive-url=https://web.archive.org/web/20080911131555/http://www-bcf.usc.edu/~krylov/pubs/pdf/jpca-110-4854.pdf |archive-date=2008-09-11 |url-status=dead}}</ref> [[Cyanogen]], {{chem2|(CN)2}}, is used to measure the temperature of [[Molecular cloud|interstellar gas clouds]].<ref>{{cite journal |title = Interstellar Cyanogen and the Temperature of the Cosmic Microwave Background Radiation |author1=Roth, K. C. |author2=Meyer, D. M. |author3=Hawkins, I.|author3-link=Isabel Hawkins |journal = The Astrophysical Journal |year = 1993 |volume = 413 |issue = 2 |pages = L67–L71 |doi = 10.1086/186961 |bibcode = 1993ApJ...413L..67R |url = http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1993ApJ...413L..67R&amp;data_type=PDF_HIGH&amp;whole_paper=YES&amp;type=PRINTER&amp;filetype=.pdf}}</ref>

===Pyrolysis and combustion product===
Hydrogen cyanide is produced by the combustion or [[pyrolysis]] of certain materials under oxygen-deficient conditions. For example, it can be detected in the [[exhaust gas|exhaust]] of [[internal combustion engine]]s and [[tobacco]] smoke. Certain [[plastic]]s, especially those derived from [[acrylonitrile]], release hydrogen cyanide when heated or burnt.<ref name="CDC"/>

===Organic derivatives===
{{Main|Nitriles}}
{{see also|Isocyanide}}
In [[IUPAC nomenclature of organic chemistry|IUPAC nomenclature]], [[organic compound]]s that have a {{chem2|\sC\tN}} [[functional group]] are called [[nitrile]]s.<ref>[[IUPAC Gold Book]] [http://goldbook.iupac.org/N04151.html ''nitriles'']</ref><ref>NCBI-MeSH [https://www.ncbi.nlm.nih.gov/mesh/68009570 ''Nitriles'']</ref> An example of a nitrile is [[acetonitrile]], {{chem2|CH3\sC\tN}}. Nitriles usually do not release cyanide ions. A functional group with a hydroxyl {{chem2|\sOH}} and cyanide {{chem2|\sCN}} bonded to the same carbon atom is called [[cyanohydrin]] ({{chem2|R2C(OH)CN}}). Unlike nitriles, cyanohydrins do release poisonous [[hydrogen cyanide]].