Chlorination of Benzene

Introduction:

The chlorination of benzene involves the introduction of a chlorine atom onto the benzene ring through electrophilic aromatic substitution. A Lewis acid typically catalyzes the reaction, often iron (III) chloride (FeCl₃). Here is the reaction with a concise explanation:

Here is a step-by-step mechanism for the chlorination of benzene:

Step 1: Formation of electrophile:

The Lewis acid catalyst (FeCl₃) helps generate an electrophile (Cl⁺) by causing the polarisation of the chlorine molecule.

Step 2: Formation of carbocation

The electrophile (Cl⁺) attacks the benzene ring to form an intermediate of carbonation, which is resonance stabilized. It is a slow step.

Step 3: Protonation

Proton transfer from the carbocation to form chlorobenzene.