Explain the mechanism of halogenation or chlorination of benzene.

Explanation

Halogenation : Benzene reacts with chlorine in the presence of `FeCl_(3)` or `AlCl_(3)` to form chlorobenzene.

Mechanism : this involves the following steps:
steps 1 : Generation of electrophile `Cl - Cl + FeCl_(3) rarr Cl^(+) + FeCl_(4)^(-)`
Steps 2 : The electrophile `Cl^(+)` attacks benzene ring to form a carbon cation which is resonance stabilised.

Loss of proton to give chlorobenzene. The proton is removed by `FeCl_(4)`.