Question

Aldehydes are more reactive than ketones.

• A. True
• B. False

Answer 1

The correct option is A True

Aldehydes are more reactive than ketones. The decreasing order of the reactivity is $H-\underset{\underset{O}{||}}{C}-H>R-\underset{\underset{O}{||}}{C}-H>R-\underset{\underset{O}{||}}{C}-R$
The reactivity of carbonyl group depends on two factors:
(i) magnitude of positive charge on carbonyl carbon atom (electrophilic character)
(ii) crowding around the carbonyl carbon atom (steric effect)
In aldehydes, there is only one alkyl group (+I effect) whereas in ketones, there are two such alkyl groups. Hence, the magnitude of positive charge on carbonyl carbon atom in aldehydes is more than the magnitude of positive charge on carbonyl carbon in ketones.
Also, ketones are more crowded than aldehydes.