Aldehydes and ketones are reduced to primary and secondary alcohols respectively. Any one of the following reducing agents can be used for this purpose.
The carbonyl group in aldehydes and ketones can be reduced to −CH2 group to form hydrocarbons.
Zinc amalgam (Zn-Hg) and conc. HCl are used for reduction of aldehydes and ketones to hydrocarbons. Reduction of aldehydes and ketones by this method is known as Clemmensen reduction.
Alternatively, the carbonyl group can be reduced to hydrocarbon using hydrazine (NH2−NH2) followed by heating with sodium or potassium hydroxide in high boiling solvent such as ethylene glycol. Reduction by this method is known as Wolff-Kishner reduction.