BRAINCAKEReaction with KCN and Hydroxynitriles
Aldehydes and ketones react with potassium cyanide, KCN, followed by dilute acid, to form hydroxynitriles. These contain both an OH group and a nitrile group, C≡N, on the same carbon.
The reaction is a nucleophilic addition. The cyanide ion, :CN−, is the nucleophile: its lone pair on carbon attacks the δ+ carbonyl carbon, the C=O π electrons move onto oxygen to give an O− intermediate, and this is then protonated by H+ from the dilute acid.
Overall, H and CN add across the C=O bond:
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Key terms in this lesson
- nucleophile
- An electron pair donor that is attracted to a region of positive charge and forms a new covalent bond by donating both electrons.
More in Aldehydes and Ketones
- Aldehydes and Ketones
- Naming Carbonyl Compounds
- Oxidation of Aldehydes
- Tollens' Reagent
- Fehling's Solution
- Reduction with NaBH4
- Nucleophilic Addition Mechanism
- Hazards of KCN
All 9 lessons in Aldehydes and Ketones · All AQA A-level Chemistry topics