Mechanism of the reaction is as depicted:
Can you think why does NO2 group show its effect only at ortho- and para- positions
and not at meta- position As shown, the presence of nitro group at ortho- and para-positions withdraws the
electron density from the benzene ring and thus facilitates the attack of the nucleophile
on haloarene The carbanion thus formed is stabilised through resonance The negative
charge appeared at ortho- and para- positions with respect to the halogen substituent is
stabilised by –NO2 group while in case of meta-nitrobenzene, none of the resonating
structures bear the negative charge on carbon atom bearing the –NO2 group