Cyanohydrierung

Cyanohydrierung is a chemical reaction that involves the addition of hydrogen cyanide (HCN) to a carbonyl group, typically an aldehyde or a ketone, to form a cyanohydrin. This reaction is a nucleophilic addition where the cyanide ion (CN-) acts as the nucleophile and attacks the electrophilic carbon atom of the carbonyl group. The reaction is often catalyzed by a base or an acid. In base-catalyzed cyanohydrin formation, a base deprotonates HCN to form the cyanide ion, which then attacks the carbonyl carbon. In acid-catalyzed cyanohydrin formation, the acid protonates the carbonyl oxygen, making the carbonyl carbon more electrophilic and thus more susceptible to nucleophilic attack by HCN. Cyanohydrins are versatile intermediates in organic synthesis. They can be hydrolyzed to alpha-hydroxy acids, reduced to beta-amino alcohols, or undergo other transformations to create a variety of functionalized molecules. The formation of cyanohydrins is a reversible reaction, and the position of equilibrium depends on the specific carbonyl compound and the reaction conditions. For simple aldehydes and ketones, the equilibrium generally favors the cyanohydrin product. However, for more sterically hindered or electron-deficient carbonyl compounds, the equilibrium may lie more towards the starting materials. Cyanohydrins themselves can be chiral if the original carbonyl compound is prochiral. This allows for the asymmetric synthesis of chiral cyanohydrins using chiral catalysts or auxiliaries, which is important for the production of enantiomerically pure compounds.