Review Of Adding Br2 And Light To Aromatic Ring References. Unlike alkenes, benzene does not undergo rapid chlorination or bromination with cl 2 or br 2. Each step requires more vigourous conditions.
Electrophilic addition of cl_2 or br_2 to an aromatic ring requires the presence of a lewis acid catalyst such as feci_3, febr_3, aici_3, or aibr_3. Positions they can be added precisely at those positions if br (bromination) is the first step. The reactions happen at room temperature.
