Question

Why is CH\(_3\)CHO more reactive than acetone towards reaction with HCN?

Hint:

Aldehydes are more reactive than ketones due to less steric hindrance and weaker +I effect.

Answer 1

Concept: Reactivity of carbonyl compounds toward nucleophilic addition depends on:

• Steric hindrance
• +I effect of alkyl groups

Reason 1: Steric factor. Acetaldehyde (CH\(_3\)CHO) has one alkyl group, while acetone has two. More crowding in acetone → less reactive.
Reason 2: Inductive effect. Two methyl groups in acetone donate electrons (+I effect), reducing electrophilicity of carbonyl carbon.
Conclusion: \[ \text{CH}_3CHO>\text{Acetone in reactivity toward HCN} \]