Cyanohydrin: Difference between revisions
Episcophagus (talk | contribs) →Other cyanohydrins: "cyanohydrins" => "cyanogenic glycosides". Amygdalin is not a cyanohydrin as it lacks the OH-group - i.e. it is RR'(CN)H, not RR'(CN)(OH).) |
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{{Short description|Functional group in organic chemistry}} |
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[[Image:Cyanohydrin-general-2D-skeletal.png|thumb|right|The structure of a general cyanohydrin.]] |
[[Image:Cyanohydrin-general-2D-skeletal.png|thumb|right|The structure of a general cyanohydrin.]] |
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| ⚫ | In [[organic chemistry]], a '''cyanohydrin''' or '''hydroxynitrile''' is a [[functional group]] found in [[organic compound]]s in which a [[Cyanide|cyano]] and a [[hydroxy group]] are attached to the same carbon atom. The general formula is {{chem2|R2C(OH)CN}}, where R is H, [[alkyl]], or [[aryl]]. Cyanohydrins are industrially important precursors to [[carboxylic acid]]s and some [[amino acid]]s. Cyanohydrins can be formed by the [[cyanohydrin reaction]], which involves treating a [[ketone]] or an [[aldehyde]] with [[hydrogen cyanide]] (HCN) in the presence of excess amounts of [[sodium cyanide]] (NaCN) as a catalyst:<ref name=CR>{{cite journal | title = The Preparation of Nitriles | author = David T. Mowry | journal = [[Chem. Rev.]] | year = 1948 | volume = 42 | issue = 2 | pages = 189–283 | doi = 10.1021/cr60132a001 | pmid=18914000}}</ref> |
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| ⚫ | In this reaction, the [[nucleophilic]] |
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| ⚫ | In this reaction, the [[nucleophilic]] {{chem2|CN−}} ion attacks the [[electrophilic]] carbonyl carbon in the ketone, followed by protonation by HCN, thereby regenerating the [[cyanide anion]]. Cyanohydrins are also prepared by displacement of [[sulfite]] by cyanide salts:<ref name=Corson>{{OrgSynth | author = Corson, B. B. | author2 = Dodge, R. A. | author3 = Harris, S. A. | author4 = Yeaw, J. S. | title = Mandelic Acid | collvol = 1 | collvolpages = 336 | year = 1941 | prep = cv1p0336}}</ref> |
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==Acetone cyanohydrins== |
==Acetone cyanohydrins== |
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:[[Image:LiCN-from-acetone-cyanohydrin-2D-skeletal.png|400px]] |
:[[Image:LiCN-from-acetone-cyanohydrin-2D-skeletal.png|400px]] |
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==Preparative methods== |
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Cyanohydrins were first prepared by the addition of HCN and a catalyst (base or enzyme) to the corresponding carbonyl.<ref>North, M.; Usanov, D. L.; Young, C. Lewis Acid Catalyzed Asymmetric Cyanohydrin Synthesis. Chem. Rev. 2008, 108 (12), 5146–5226. doi:10.1021/cr800255k.</ref> On a laboratory scale the use of HCN (toxic) is largely not encouraged, for this reason other less dangerous cyanation reagents are sought out. In situ formation of HCN can be sourced using precursors such as acetone cyanohydrin. Alternatively, cyano-silyl derivatives such as TMS-CN allows for both the cyanation and protection in one step without the need for HCN.<ref>Lidy, W.; Sundermeyer, W. Spaltungsreaktionen Des Trimethylsilylcyanids, Eine Neue Darstellungsmethode Für O-(Trimethylsilyl)Cyanhydrine. Chem. Ber. 1973, 106 (2), 587–593. doi:10.1002/cber.19731060224</ref> Similar procedures relying on ester, phosphate and carbonate formation have been reported.<ref>Scholl, M.; Lim, C. K.; Fu, G. C. Convenient and Efficient Conversion of Aldehydes to Acylated Cyanohydrins Using Tributyltin Cyanide as a Catalyst. J. Org. Chem. 1995, 60 (19), 6229–6231. doi: 10.1021/jo00124a052.</ref><ref>Yoneda, R.; Harusawa, S.; Kurihara, T. Cyano Phosphate: An Efficient Intermediate for the Chemoselective Conversion of Carbonyl Compounds to Nitriles. J. Org. Chem. 1991, 56 (5), 1827–1832. doi: 10.1021/jo00005a031.</ref><ref>Juhl, M.; Petersen, A. R.; Lee, J.-W. CO2‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions. Chem. – A Eur. J. 2020. doi: 10.1002/chem.202003623.</ref> |
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[[File:Cyanohydrin synthesis.jpg|center|thumb|450x450px|Different reactions for the preparation of cyanohydrin]] |
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==Other cyanohydrins== |
==Other cyanohydrins== |
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[[Mandelonitrile]], with the formula [[benzyl|C<sub>6</sub>H<sub>5</sub>CH]](OH)CN, occurs in small amounts in the pits of some fruits.<ref name=Corson/> Related cyanogenic glycosides are known, such as [[amygdalin]].<ref name=CR/> |
[[Mandelonitrile]], with the formula [[benzyl|C<sub>6</sub>H<sub>5</sub>CH]](OH)CN, occurs in small amounts in the pits of some fruits.<ref name=Corson/> Related cyanogenic glycosides are known, such as [[amygdalin]].<ref name=CR/> |
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[[File:Amygdalin structure.svg|thumb| |
[[File:Amygdalin structure.svg|thumb|upright=1.15|[[Amygdalin]] is one of several naturally occurring cyanogenic glycosides.]] |
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[[Glycolonitrile]], also called hydroxyacetonitrile or formaldehyde cyanohydrin, is the organic compound with the formula HOCH<sub>2</sub>CN. |
[[Glycolonitrile]], also called hydroxyacetonitrile or formaldehyde cyanohydrin, is the organic compound with the formula HOCH<sub>2</sub>CN. It is the simplest cyanohydrin, being derived from [[formaldehyde]].<ref>{{OrgSynth |author=Gaudry, R. |title=Glycolonitrile |collvol=3 |collvolpages=436 |year=1955 |prep=cv3p0436}}</ref> |
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<center> |
<gallery class="center" widths="100px"> |
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File:Glyconitrile Structural FormulaV1.svg|glycolonitrile |
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{|align="center" class="wikitable" |
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File:Acetone cyanohydrin.svg|acetone cyanohydrin |
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|<center>[[Image:Glycolonitrile-2D-skeletal.png|100px]]</center>||<center>[[Image:Acetone cyanohydrin.svg|100px]]</center>||<center>[[Image:Mandelonitrile-2D-skeletal.png|100px]]</center> |
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File:Mandelonitrile-2D-skeletal.svg|mandelonitrile |
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</gallery> |
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|<center>glycolonitrile</center>||<center>acetone cyanohydrin</center>||<center>mandelonitrile</center> |
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</center> |
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==See also== |
==See also== |
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* [[Halohydrin]] |
* [[Halohydrin]] |
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* [[Benzoin condensation]] |
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==References== |
==References== |
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{{Reflist}} |
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<references/> |
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==External links== |
==External links== |
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Latest revision as of 09:22, 19 May 2024
In organic chemistry, a cyanohydrin or hydroxynitrile is a functional group found in organic compounds in which a cyano and a hydroxy group are attached to the same carbon atom. The general formula is R2C(OH)CN, where R is H, alkyl, or aryl. Cyanohydrins are industrially important precursors to carboxylic acids and some amino acids. Cyanohydrins can be formed by the cyanohydrin reaction, which involves treating a ketone or an aldehyde with hydrogen cyanide (HCN) in the presence of excess amounts of sodium cyanide (NaCN) as a catalyst:[1]
- RR’C=O + HCN → RR’C(OH)CN
In this reaction, the nucleophilic CN− ion attacks the electrophilic carbonyl carbon in the ketone, followed by protonation by HCN, thereby regenerating the cyanide anion. Cyanohydrins are also prepared by displacement of sulfite by cyanide salts:[2]
Cyanohydrins are intermediates in the Strecker amino acid synthesis. In aqueous acid, they are hydrolyzed to the α-hydroxy acid.
Acetone cyanohydrins
[edit]Acetone cyanohydrin, (CH3)2C(OH)CN is the cyanohydrin of acetone. It is generated as an intermediate in the industrial production of methyl methacrylate.[3] In the laboratory, this liquid serves as a source of HCN, which is inconveniently volatile.[4] Thus, acetone cyanohydrin can be used for the preparation of other cyanohydrins, for the transformation of HCN to Michael acceptors, and for the formylation of arenes. Treatment of this cyanohydrin with lithium hydride affords anhydrous lithium cyanide:
Preparative methods
[edit]Cyanohydrins were first prepared by the addition of HCN and a catalyst (base or enzyme) to the corresponding carbonyl.[5] On a laboratory scale the use of HCN (toxic) is largely not encouraged, for this reason other less dangerous cyanation reagents are sought out. In situ formation of HCN can be sourced using precursors such as acetone cyanohydrin. Alternatively, cyano-silyl derivatives such as TMS-CN allows for both the cyanation and protection in one step without the need for HCN.[6] Similar procedures relying on ester, phosphate and carbonate formation have been reported.[7][8][9]
Other cyanohydrins
[edit]Mandelonitrile, with the formula C6H5CH(OH)CN, occurs in small amounts in the pits of some fruits.[2] Related cyanogenic glycosides are known, such as amygdalin.[1]
Glycolonitrile, also called hydroxyacetonitrile or formaldehyde cyanohydrin, is the organic compound with the formula HOCH2CN. It is the simplest cyanohydrin, being derived from formaldehyde.[10]
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glycolonitrile -
acetone cyanohydrin -
mandelonitrile
See also
[edit]References
[edit]- ^ a b David T. Mowry (1948). "The Preparation of Nitriles". Chem. Rev. 42 (2): 189–283. doi:10.1021/cr60132a001. PMID 18914000.
- ^ a b Corson, B. B.; Dodge, R. A.; Harris, S. A.; Yeaw, J. S. (1941). "Mandelic Acid". Organic Syntheses; Collected Volumes, vol. 1, p. 336.
- ^ 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
- ^ Haroutounian, S. A. "Acetone Cyanohydrin" Encyclopedia of Reagents for Organic Synthesis 2001, John Wiley & Sons. doi:10.1002/047084289X.ra014
- ^ North, M.; Usanov, D. L.; Young, C. Lewis Acid Catalyzed Asymmetric Cyanohydrin Synthesis. Chem. Rev. 2008, 108 (12), 5146–5226. doi:10.1021/cr800255k.
- ^ Lidy, W.; Sundermeyer, W. Spaltungsreaktionen Des Trimethylsilylcyanids, Eine Neue Darstellungsmethode Für O-(Trimethylsilyl)Cyanhydrine. Chem. Ber. 1973, 106 (2), 587–593. doi:10.1002/cber.19731060224
- ^ Scholl, M.; Lim, C. K.; Fu, G. C. Convenient and Efficient Conversion of Aldehydes to Acylated Cyanohydrins Using Tributyltin Cyanide as a Catalyst. J. Org. Chem. 1995, 60 (19), 6229–6231. doi: 10.1021/jo00124a052.
- ^ Yoneda, R.; Harusawa, S.; Kurihara, T. Cyano Phosphate: An Efficient Intermediate for the Chemoselective Conversion of Carbonyl Compounds to Nitriles. J. Org. Chem. 1991, 56 (5), 1827–1832. doi: 10.1021/jo00005a031.
- ^ Juhl, M.; Petersen, A. R.; Lee, J.-W. CO2‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions. Chem. – A Eur. J. 2020. doi: 10.1002/chem.202003623.
- ^ Gaudry, R. (1955). "Glycolonitrile". Organic Syntheses; Collected Volumes, vol. 3, p. 436.