The reaction between benzene and bromine in the presence of an iron catalyst is an example of electrophilic aromatic substitution. The specific reaction is called bromination of benzene. The mechanism for this reaction can be described in the following steps:1. Catalyst activation: The iron catalyst usually FeBr3 or Fe reacts with bromine Br2 to form the electrophile, the bromonium ion Br+ . This step generates a highly reactive electrophile that can attack the aromatic ring.FeBr3 + Br2 FeBr4- + Br+2. Electrophilic attack: The electrophile Br+ attacks the benzene ring, which is rich in electron density due to the presence of the delocalized electrons. This attack leads to the formation of a resonance-stabilized carbocation intermediate called a sigma complex or arenium ion. The aromaticity of the benzene ring is temporarily lost in this step.Benzene + Br+ Sigma complex arenium ion 3. Deprotonation: A base in this case, the FeBr4- ion abstracts a proton from the sigma complex, restoring the aromaticity of the benzene ring and forming the final bromobenzene product. The iron catalyst is also regenerated in this step.Sigma complex + FeBr4- Bromobenzene + HBr + FeBr3The intermediate formed during the reaction, the sigma complex arenium ion , has a positive charge on the carbon atom where the electrophile attacked. The positive charge is delocalized over three carbon atoms of the benzene ring through resonance, and a hydrogen atom is still attached to the carbon with the bromine atom. The aromaticity of the benzene ring is temporarily lost in this intermediate, but it is regained after the deprotonation step.