Halogen atom besides being slightly deactivating is o, p-
directing; therefore, further substitution occurs at ortho- and para-
positions with respect to the halogen atom The o, p-directing influence
of halogen atom can be easily understood if we consider the resonating
structures of halobenzene as shown:
Due to resonance, the electron density increases more at ortho- and
para-positions than at meta-positions Further, the halogen atom
because of its –I effect has some tendency to withdraw electrons from
the benzene ring As a result, the ring gets somewhat deactivated as
compared to benzene and hence the electrophilic substitution reactions
in haloarenes occur slowly and require more drastic conditions as
compared to those in benzene