Question

Why is chlorobenzene less reactive towards nucleophilic substitution reaction?

Hint:

In reasoning questions, always consider electronic effects (inductive, resonance), medium conditions (acid/base), and steric effects for explanations.

Answer 1

Step 1: In chlorobenzene, the chlorine atom is bonded to an sp²-hybridized carbon of the benzene ring.
Step 2: The lone pair of electrons on chlorine can delocalize into the aromatic ring through resonance, creating structures where the C–Cl bond exhibits partial double bond character. This strengthens the bond and makes it difficult to break.
Step 3: Additionally, the benzene ring is electron-rich, which repels nucleophiles (electron donors), making nucleophilic attack less favorable.
Conclusion: Due to resonance and the resulting partial double bond character, as well as electronic repulsion from the aromatic ring, chlorobenzene is much less reactive towards nucleophilic substitution than alkyl halides.