Cyanohydrin reaction: Difference between revisions
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== Asymmetric synthesis == | == Asymmetric synthesis == | ||
The [[asymmetric synthesis|asymmetric]] cyanohydrin reaction of [[benzaldehyde]] with trimethylsilylcyanide is made possible by employment of (R)-[[Binol]]<ref>{{cite journal |title=Chiral Lithium Binaphtholate Aqua Complex as a Highly Effective Asymmetric Catalyst for Cyanohydrin Synthesis |first1=Manabu |last1=Hatano |first2=Takumi |last2=Ikeno |first3=Takashi |last3=Miyamoto |first4=Kazuaki |last4=Ishihara |journal=[[J. Am. Chem. Soc.]] |year=2005 |volume=127 |issue=31 |pages=10776–77 |doi=10.1021/ja051125c|pmid=16076152 }}</ref> at 1–10% [[catalyst]] loading. This [[ligand]] firsts reacts with a lithium alkoxy compound to form a lithium binaphtholate Complex. | The [[asymmetric synthesis|asymmetric]] cyanohydrin reaction of [[benzaldehyde]] with trimethylsilylcyanide is made possible by employment of (R)-[[Binol]]<ref>{{cite journal |title=Chiral Lithium Binaphtholate Aqua Complex as a Highly Effective Asymmetric Catalyst for Cyanohydrin Synthesis |first1=Manabu |last1=Hatano |first2=Takumi |last2=Ikeno |first3=Takashi |last3=Miyamoto |first4=Kazuaki |last4=Ishihara |journal=[[J. Am. Chem. Soc.]] |year=2005 |volume=127 |issue=31 |pages=10776–77 |doi=10.1021/ja051125c|pmid=16076152 |bibcode=2005JAChS.12710776H }}</ref> at 1–10% [[catalyst]] loading. This [[ligand]] firsts reacts with a lithium alkoxy compound to form a lithium binaphtholate Complex. | ||
[[Image:Asym cyanohydrin reaction.svg|center|Asymmetric reaction of benzaldehyde with (R)–[[Binol]]–lithium(i-propyloxy) gives (S)-acetonitrile with 98% [[Enantiomer|ee]]]] | [[Image:Asym cyanohydrin reaction.svg|center|Asymmetric reaction of benzaldehyde with (R)–[[Binol]]–lithium(i-propyloxy) gives (S)-acetonitrile with 98% [[Enantiomer|ee]]]] | ||
Latest revision as of 12:15, 24 June 2025
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In organic chemistry, a cyanohydrin reaction is an organic reaction in which an aldehyde (Template:Chem2) or ketone (Template:Chem2) reacts with a cyanide anion (Template:Chem2) or a nitrile (Template:Chem2) to form a cyanohydrin (Template:Chem2). For example:
This nucleophilic addition is a reversible reaction but with aliphatic carbonyl compounds equilibrium is in favor of the reaction products. The cyanide source can be potassium cyanide (KCN), sodium cyanide (NaCN) or trimethylsilyl cyanide (Template:Chem2). With aromatic aldehydes such as benzaldehyde, the benzoin condensation is a competing reaction. The reaction is used in carbohydrate chemistry as a chain extension method for example that of D-xylose.
Examples
Reaction mechanism
Asymmetric synthesis
The asymmetric cyanohydrin reaction of benzaldehyde with trimethylsilylcyanide is made possible by employment of (R)-Binol[1] at 1–10% catalyst loading. This ligand firsts reacts with a lithium alkoxy compound to form a lithium binaphtholate Complex.
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The chemist Urech in 1872 was the first to synthesize cyanohydrins from ketones with alkali cyanides and acetic acid[2] and therefore this reaction also goes by the name of Urech cyanohydrin method.
References
External links
- Cyanohydrin reaction of formaldehyde to hydroxyacetonitrile or glycolonitrile with sodium cyanide in Organic Syntheses Coll. Vol. 2, p. 387; Vol. 13, p. 56 Article
- Cyanohydrin reaction of formaldehyde with potassium cyanide Organic Syntheses Coll. Vol. 3, p. 436; Vol. 27, p. 41 Article
- Cyanohydrin reaction of acetophenone with potassium cyanide Organic Syntheses Coll. Vol. 4, p. 58; Vol. 33, p. 7 Article
- Cyanohydrin reaction of D-xylose with potassium cyanide Organic Syntheses Coll. Vol. 4, p. 506; Vol. 36, p. 38 Article
- Cyanohydrin reaction of acetone with potassium cyanide Organic Syntheses Coll. Vol. 2, p. 7; Vol. 15, p. 1 Article
- Cyanohydrin reaction of benzoquinone with trimethylsilylcyanide Organic Syntheses Coll. Vol. 7, p. 517; Vol. 60, p. 126 Article
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