CBSE Class 12 Chemistry Notes: Aldehydes & Ketones – Chemical Properties

Aldehydes & ketones are highly reactive compounds, they undergo nucleophilic addition reactions. Their reactivity is due to presence of a polar carbonyl group. The positively charged carbon atom of carbonyl group is readily attacked by nucleophilic species for initiation of the reaction. This leads to formation of intermediate anion which further undergoes the attack of H⁺ ion or other positively charged species to form the final product. The reaction in general may be represented as:

Relative reactivity of aldehydes & ketones

In general ketones are less reactive than aldehydes on a account of following facts:

(i) Electron releasing effect of two alkyl groups, decreases the magnitude of positive charge on ketones.

(ii) Steric effect caused by two alkyl groups also hinders the approach of the nucleophile to the carbonyl carbon.

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