In organic chemistry, an electrophilic aromatic halogenation is a type of electrophilic aromatic substitution. This organic reaction is typical of aromatic compounds and a very useful method for adding substituents to an aromatic system.
A few types of aromatic compounds, such as phenol, will react without a catalyst, but for typical benzene derivatives with less reactive substrates, a Lewis acid catalyst is required. Typical Lewis acid catalysts include AlCl3, FeCl3, FeBr3, and ZnCl2. These work by forming a highly electrophilic complex which attacks the benzene ring.