Cyanohydrin

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The structure of a general cyanohydrin.

In ,

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

cyanide anion. Cyanohydrins are also prepared by displacement of sulfite by cyanide salts:[2]

Cyanohydrins are intermediates in the

α-hydroxy acid
.

Acetone cyanohydrins

arenes. Treatment of this cyanohydrin with lithium hydride affords anhydrous
lithium cyanide:

Preparative methods

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]

Different reactions for the preparation of cyanohydrin

Other cyanohydrins

C6H5CH(OH)CN, occurs in small amounts in the pits of some fruits.[2] Related cyanogenic glycosides are known, such as amygdalin.[1]

Amygdalin is one of several naturally occurring cyanogenic glycosides.

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]

  • glycolonitrile
    glycolonitrile
  • acetone cyanohydrin
    acetone cyanohydrin
  • mandelonitrile
    mandelonitrile

See also

References

  1. ^
    PMID 18914000
    .
  2. ^ 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.
  3. doi:10.1002/14356007.a16_441
    . Article Online Posting Date: June 15, 2000
  4. doi:10.1002/047084289X.ra014
  5. ^ North, M.; Usanov, D. L.; Young, C. Lewis Acid Catalyzed Asymmetric Cyanohydrin Synthesis. Chem. Rev. 2008, 108 (12), 5146–5226. doi:10.1021/cr800255k.
  6. ^ 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
  7. ^ 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.
  8. ^ 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.
  9. ^ 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.
  10. ^ Gaudry, R. (1955). "Glycolonitrile". Organic Syntheses; Collected Volumes, vol. 3, p. 436.

External links

  • Gold Book definition of cyanohydrins [1]
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