Chlorination [Cl2 plus catalyst]
Chlorination [Cl2 plus catalyst] Definition:
Treatment of an aromatic (such as benzene) with chlorine (Cl2) and a Lewis base such as AlCl3 or FeCl3 leads to the formation of the chlorinated aromatic by electrophilic aromatic substitution.
Chlorination [Cl2 plus catalyst] Explained:
This reaction is similar to catalytic aromatic bromination. Benzene does undergo electrophilic aromatic substitution with chlorine and aluminum chloride as a catalyst to produce chlorobenzene.
Chlorine reacts with AlCl3 to form a complex in which imparting electrophilic character to the chlorine atom [1]. This electrophilic chlorine atom reacts in the next step [2], the nucleophilic attack of benzene. Sigma complex, or arenium ion, is also formed. The reaction ends [3] by deprotonation of sigma complex and, thereby, restoring aromaticity and regenerating the Lewis acid (AlCl3).