Reduction of the carbonyl group to CH₂ occurs with zinc-amalgam and concentrated hydrochloric acid (Clemmensen reduction) or hydrazine followed by heating with sodium or potassium hydroxide in ethylene glycol (Wolff-Kishner reduction).

Aldehydes are reduced to primary alcohols, and ketones to secondary alcohols, using sodium borohydride (NaBH₄), lithium aluminium hydride (LiAlH₄), or catalytic hydrogenation.

Aldehydes are more reactive due to both steric and electronic reasons. Sterically, the hindered approach of nucleophile to the carbonyl carbon is less in aldehydes. Electronically, aldehydes are more reactive because two alkyl groups in ketones reduce the electrophilicity of ...

Aldehydes and ketones are commonly prepared by the oxidation of primary and secondary alcohols, respectively.

Carbonyl compounds have a planar structure with a π-bond, leading to substantial dipole moments. The high polarity is explained by resonance, involving neutral (A) and dipolar (B) structures, contributing to the overall dipole moment of carbonyl compounds.