Reactivity of carbonyl compounds:

The reactivity of carbonyl compounds is influenced by the electron-withdrawing ability of the group attached to the carbonyl carbon.

* Acid chlorides have a highly electronegative chlorine atom attached to the carbonyl carbon, making the carbonyl carbon more electrophilic and susceptible to nucleophilic attack.

* Aldehydes have a less electronegative hydrogen atom attached to the carbonyl carbon, making the carbonyl carbon less electrophilic than in acid chlorides.

Reasons for the higher reactivity of acid chlorides:

1. Stronger electron-withdrawing effect: The chlorine atom in acid chlorides is a strong electron-withdrawing group, which increases the positive charge density on the carbonyl carbon, making it more susceptible to nucleophilic attack.

2. Good leaving group: The chloride ion (Cl-) is a good leaving group, facilitating the departure of the chlorine atom during nucleophilic attack.

3. Resonance stabilization: The carbonyl group in acid chlorides is stabilized by resonance, which makes the carbonyl carbon more electrophilic.

Conclusion:

Due to the stronger electron-withdrawing effect, good leaving group, and resonance stabilization, acid chlorides are more reactive than aldehydes towards nucleophilic attack.