Aromatic aldehydes are less reactive than aliphatic aldehydes in nucleophilic addition reaction. Give reason.

Aromatic aldehydes are generally less reactive than aliphatic aldehydes in nucleophilic addition reactions due to the electron-donating and electron-withdrawing effects of the aromatic ring.

Electron-Withdrawing Effect of Aromatic Ring: Aromatic rings, such as benzene rings, contain conjugated pi electrons that can delocalize around the ring. These pi electrons can interact with the electron pair of the carbonyl group in the aldehyde, making it less available for attack by nucleophiles. The delocalization of pi electrons in the aromatic ring exerts an electron-withdrawing effect, which reduces the electron density on the carbonyl carbon atom. This reduced electron density makes it less susceptible to nucleophilic attack.

Resonance Stabilization: Aromatic compounds can undergo resonance stabilization, which spreads the negative charge across multiple atoms in the ring. This resonance stabilization helps in reducing the reactivity of the carbonyl group. In contrast, aliphatic aldehydes lack this resonance stabilization, and the electron density on the carbonyl carbon is more localized, making it more susceptible to nucleophilic attack.

Steric Effects: Aromatic aldehydes often have bulky aromatic groups attached to the carbonyl carbon. These bulky groups can hinder the approach of nucleophiles to the carbonyl carbon, reducing the reaction rate. Aliphatic aldehydes, on the other hand, typically have smaller alkyl groups, which do not create as much steric hindrance.

Overall, the combination of electron-withdrawing effects, resonance stabilization, and steric hindrance in aromatic aldehydes makes them less reactive toward nucleophilic addition reactions compared to aliphatic aldehydes.