Directive Influence of Halogen atom in Haloarenes:
In haloarenes, the halogen atom present in the ring is ortho and para directing in nature and therefore in a substitution reaction, a mixture of isomeric products is formed, in which the para-isomer is the major product since the para position is less hindered in the molecule of haloarene compared to ortho position.
In haloarenes, the halogen atom has also a strong –I (inductive) effect which is likely to deactivate the ring and the electrophilic attack will become rather difficult. However, +M effect dominates over the –I effect when the electrophile is directed to ortho and para position in the ring. Therefore, the electrophilic substitution takes place at these positions though with difficulty. The electrophilic attack is not feasible at the meta position in the ring because the +M effect is rather weak and –I effect of the halogen atom is expressed to have greater magnitude.
