Reactions of Aldehydes & Ketones
Reduction of aldehyde & ketones
- Aldehydes and ketones can be reduced by reducing agents such as NaBH4 or LiAlH4
- Aldehydes are reduced to primary alcohols
- Ketones are reduced to secondary alcohols
Reduction of ethanal and propanone
Aldehydes are reduced to form primary alcohols, while ketones are reduced to to form secondary alcohols
Nucleophilic addition with HCN
- Aldehydes and ketones can undergo nucleophilic addition with hydrogen cyanide, HCN
- The cyanide ion, CN-, acts as a nucleophile and adds across the C-O bond
- Aldehydes and ketones react with HCN, KCN as catalyst and heat to produce hydroxynitriles
- Hydroxynitriles are nitriles containing a hydroxy, -OH, group
Nucleophilic addition of HCN to ethanal and propanone
The nucleophilic addition of HCN to aldehydes always forms a chiral hydroxy nitrile compound, while the nucleophilic addition of HCN to ketones may form a chiral hydroxy nitrile compound
Examiner Tip
The nucleophilic addition of HCN to an aldehyde or ketone increases the length of the carbon chain by one carbon atom!
