Question

Although chlorine is an electron withdrawing group, yet it is ortho-, para- directing in electrophilic aromatic substitution reactions. Why?

Answer 1

 Chlorine is an electron-withdrawing group, yet it is ortho-, para- directing in electrophilic aromatic substitution reactions. This is because Cl exhibits positive mesomeric effect as well. By virtue of resonance, Cl tends to stabilise the carbocation and increases the electron density more at ortho- and para- positions than at meta- position of the benzene ring. Thus, electrophilic aromatic substitution reactions take place at ortho- and para- positions.