Editing Cyanohydrin (section)

==Preparative methods==
Cyanohydrins are traditionally prepared by the addition of HCN to the corresponding carbonyl.  The reaction is typically catalyzed by base or an enzyme.<ref name=CR1>{{cite journal| doi=10.1021/cr800255k| title=Lewis Acid Catalyzed Asymmetric Cyanohydrin Synthesis| date=2008| last1=North| first1=Michael| last2=Usanov| first2=Dmitry L.| last3=Young| first3=Carl| journal=Chemical Reviews| volume=108| issue=12| pages=5146–5226| pmid=19067648}}</ref><ref name=CR2>{{cite journal| doi=10.1021/cr9902906| title=Cyanohydrins in Nature and the Laboratory: Biology, Preparations, and Synthetic Applications| date=1999| last1=Gregory| first1=Robert J. H.| journal=Chemical Reviews| volume=99| issue=12| pages=3649–3682| pmid=11849033}}</ref> Because of the hazards with HCN, other less dangerous cyanation reagents are often used.<ref>{{cite journal| doi=10.1002/chem.202003623| title=CO<sub>2</sub>-Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions*| date=2021| last1=Juhl| first1=Martin| last2=Petersen| first2=Allan R.| last3=Lee| first3=Ji-Woong| journal=Chemistry – A European Journal| volume=27| pages=228–232}}</ref>  
*[[Trimethylsilyl cyanide]], affording the silyl ether derivative of the cyanohydrin
*[[Diethylaluminium cyanide]], especially for less reactive carbonyls
*[[Diethyl phosphorocyanidate]] (DEPC) and lithium cyanide
*[[Acyl cyanide]]s (RC(O)CN)
[[File:Cyanohydrin synthesis.jpg|center|thumb|450x450px|Reactions leading to the preparation of cyanohydrin]]

===Transhydrocyanation===
[[Acetone cyanohydrin]], (CH<sub>3</sub>)<sub>2</sub>C(OH)CN is the cyanohydrin of [[acetone]].  It is generated as an intermediate in the industrial production of [[methyl methacrylate]].<ref>William Bauer, Jr. "Methacrylic Acid and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a16_441}}. Article Online Posting Date: June 15, 2000</ref>  In the laboratory, this liquid serves as a source of HCN. The process is called '''transhydrocyanation''', where acetone cyanohydrin, is used as a source of HCN.<ref name=CR1/><ref name=CR2/><ref>Haroutounian, S. A. "Acetone Cyanohydrin" Encyclopedia of Reagents for Organic Synthesis 2001, John Wiley & Sons. {{doi|10.1002/047084289X.ra014}}</ref>  Thus, acetone cyanohydrin can be used for the preparation of other cyanohydrins, for the transformation of HCN to  [[Michael addition|Michael acceptor]]s, and for the [[Gattermann-Koch reaction|formylation]] of [[arene]]s.  Treatment of this cyanohydrin with [[lithium hydride]] affords [[anhydrous]] lithium cyanide:
:[[Image:LiCN-from-acetone-cyanohydrin-2D-skeletal.png|400px]]

===Asymmetric cyanohydrin formation===
Formation of cyanohydrins introduces a chiral center for aldehydes and for unsymmetrical ketones.  The enantioselective hydrocyanation has attracted some attention for the preparation of 2-chloromandelic acid, a drug precursor.<ref name=CR1/>

<gallery caption="Some Prominent Cyanohydrins" widths="120px" heights="90px">
File:Glyconitrile Structural FormulaV1.svg|glycolonitrile, also called hydroxyacetonitrile or formaldehyde cyanohydrin, is the simplest cyanohydrin.<ref>{{OrgSynth |author=Gaudry, R. |title=Glycolonitrile |collvol=3 |collvolpages=436 |year=1955 |prep=cv3p0436}}</ref>
File:Acetone cyanohydrin.svg|acetone cyanohydrin
File:Mandelonitrile-2D-skeletal.svg|mandelonitrile, occurs in small amounts in the pits of some fruits.<ref name=Corson/>
File:Amygdalin structure.svg|[[Amygdalin]], a naturally occurring cyanogenic glycoside
</gallery>