Inductive effect - Relative reactivity of aldehydes and ketones
The comparative re-activities of aldehydes and ketones in nucleophilic addition reactions might be attributed to the amount of positive charge on the carbon. As a higher positive charge seems a higher reactivity. Determine if the positive charge is detached throughout the molecule, the carbonyl compound turns out to be much more stable and its reactivity decreases. Here now, alkyl set is an electron releasing group (+I inductive effect). Hence, electron releasing energy of two alkyl groups in ketones is much more than that of one alkyl set in aldehyde. Since a product, the electron deficiency of carbon atom in the carbonyl group is satisfied much more in ketones as compared to in aldehydes. Hence, the replaced positive charge on carbon in case of ketones discourages the attack of nucleophiles. Therefore ketones are minimum reactive as compared to aldehydes. Formaldehyde correlated to no alkyl sets is the most reactive of the aldehydes and ketones. So, the order of reactivity is: