Cyanohydrin reaction

A Cyanohydrin reaction is an organic reaction by an aldehyde or ketone with a cyanide anion or a nitrile to form a cyanohydrin. 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, sodium cyanide or trimethylsilylcyanide. With aromatic aldehydes such as benzaldehyde the benzoin condensation is a competing reaction. The reaction is used in carbohydrate chemistry as a chain extention method for example that of D-xylose.

Reaction of acetone with sodium cyanide to hydroxyacetonitrile

Reaction of acetone with sodium cyanide to hydroxyacetonitrile

Reaction of acetone with sodium cyanide to hydroxyacetonitrile

Reaction of benzoquinone with trimethylsilylcyanide, catalyst KCN is introduced as a 1:1 complex with the Crown ether 18-crown-6

Reaction of benzoquinone with trimethylsilylcyanide, catalyst KCN is introduced as a 1:1 complex with the Crown ether 18-crown-6

Reaction of benzoquinone with trimethylsilylcyanide in tetrachloromethane, catalyst KCN is introduced as a 1:1 complex with the Crown ether 18-crown-6

chain extention of D-xylose in equilibrium with its hemiacetal with KCN to the cyclic ester

chain extention of D-xylose in equilibrium with its hemiacetal with KCN to the cyclic ester

The asymmetric cyanohydrin reaction of benzaldehyde with trimethylsilylcyanide is made possible by employment of (R)-Binol ¹ at 1 to 10% catalyst loading. This ligand firsts reacts with a lithium alcoxy compound to form a lithium binaphtholate Complex.

Asymmetric reaction of benzaldehyde with (R)-Binol-lithium(i-propyloxy) gives (S)-cyanohydrin with 98% ee

Asymmetric reaction of benzaldehyde with (R)-Binol-lithium(i-propyloxy) gives (S)-cyanohydrin with 98% ee

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.41Article
• 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

References

• ¹ Chiral Lithium Binaphtholate Aqua Complex as a Highly Effective Asymmetric Catalyst for Cyanohydrin Synthesis Manabu Hatano, Takumi Ikeno, Takashi Miyamoto, and Kazuaki Ishihara J. Am. Chem. Soc.; 2005; 127(31) pp 10776 - 10777 AbstractSupport info plus proposed transition state