Introduction of Halogens into the Ring
Benzene reacts with halogens in the presence of Lewis acids, substituting one of its hydrogens for the halogen.
Mechanism of Halogenation
The catalyst interacts with one of the Br atoms, polarizing the bond in such a way that the other bromine acquires enough positive polarity to be attacked by benzene. The second stage of the reaction consists of the reacquisition of the ring's aromaticity through the loss of a proton.
Stage 1. Attack of benzene on the electrophile (bromine). The catalyst polarizes the bromine molecule.
Stage 2. Rearomatization of Benzene
