Synthesis of cyanohydrin

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The cyanohydrin synthesis describes the production of cyanohydrins by the base-catalyzed addition of hydrocyanic acid (HCN) to carbonyl compounds ( aldehydes or ketones ). This process allows sugar to be increased by one carbon unit.


This variant of the cyanohydrin synthesis was developed by Heinrich Kiliani (1855–1945). Originally, however, Adolph Strecker developed a synthesis that is also known as the cyanohydrin synthesis for the representation of amino acids . With this variant, alanine was first synthesized from acetaldehyde and HCN as early as 1850 .

Enzymatic synthesis

The production of cyanohydrins is also possible via biocatalytic synthesis. The enzyme that is used for this is a hydroxynitrile lyase (HNL). HNLs are e.g. B. in green almond kernels , in the needles of the yew or in the tropical golden spotted fern and are responsible for the toxicity of this plant material. Since cyanohydrins are chiral compounds , the corresponding enantiomers can be obtained with a high degree of purity via ( R ) - or ( S ) -hydroxynitrile lyases .

Enzymatic activity of hydroxynitrile lyases

The reaction represents the addition and release of or to aldehydes and ketones . The forward reaction describes cyanogesis in plants, the reverse reaction describes the biocatalytic cyanohydrin synthesis.

Individual evidence

  1. LF Fieser, M. Fieser: Textbook of organic chemistry. 3. Edition. Verlag Chemie, 1957, p. 507.