The reaction between benzene and bromine in the presence of FeBr3 as a catalyst is known as electrophilic aromatic substitution specifically, bromination . In this reaction, one of the hydrogen atoms on the benzene ring is replaced by a bromine atom. The mechanism of this reaction can be explained in the following steps:1. Catalyst activation: The FeBr3 catalyst reacts with a bromine molecule Br2 to form a complex, FeBr3-Br, which is a highly electrophilic species. This step generates the electrophile needed for the reaction. FeBr3 + Br2 FeBr3-Br2. Electrophilic attack: The electrophilic FeBr3-Br complex attacks the electron-rich benzene ring, breaking one of the pi bonds in the ring and forming a sigma bond with the bromine atom. This results in the formation of a positively charged intermediate called a sigma complex or arenium ion. The positive charge is delocalized over the carbon atoms in the ring, making the intermediate relatively stable.3. Deprotonation: A base usually the bromide ion, Br- abstracts a proton from the carbon atom that is bonded to the newly added bromine atom in the sigma complex. This step regenerates the aromaticity of the benzene ring by reforming the pi bond and restores the original planar structure of the ring. The catalyst, FeBr3, is also regenerated in this step and can participate in further reactions. Sigma complex + Br- Bromobenzene + HBr + FeBr3Overall, the reaction can be summarized as: Benzene + Br2 Bromobenzene + HBrThe electrophilic aromatic substitution mechanism allows benzene to maintain its aromaticity throughout the reaction, which is crucial for the stability of the molecule. The use of FeBr3 as a catalyst lowers the activation energy of the reaction and increases the electrophilicity of the bromine, making the reaction more efficient and selective.