Explain aromatic electroplhilic substitution reactions of benzene.

Explanation

Electrophilic substitution reaction of benzene proceeds in two steps.
Step 1: The clectrophile (E') takes two electrons of the six - electron `pi` system, to form a `sigma` bond with a carbon atom of the benzene ring. Then that carbon atom becomes `sp^(3)` hybridised.

Step 2: A proton is removed from the carbon atom of the `sigma` complex that bears the E (electrophile). Then that carbon atom changes to `sp^(2)` state again. Then the benzene derivative with fully delocalised six `pi` electrons is formed.

(The proton `H^(**)` combines with the anion obtained from the molecule `E-AtoE^(**) + :A)`