Question

Why does the presence of a nitro group make the benzene ring less reactive in comparison to the unsubstituted benzene ring? Explain.

Answer 1

Nitro group is an electron withdrawing group which decreases the electron density from a benzene ring by $-I$ effect (inductive effect ) and $-R$ effect (resonance effect ).

Resonance effect by nitro group can be represented as:



Due to, this decrease in electron density from benzene ring, the nitrobenzene reactivity decreases for the attack of electrophiles. (during electrophilic substitution reactions ).

Thus, presence of a nitro group make the benzene ring less reactive in comparison to the unsubstituted benzene ring.