Question

Propose a mechanism for the aluminum chloride-catalyzed reaction of benzene with chlorine.

Short answer

The mechanism for the aluminum chloride-catalyzed reaction of benzene with chlorine is as follows:

Step-by-step solution

Chlorination of benzene

The chlorination of benzene works much like bromination except when${\mathrm{AlCl}}_3$ is used as a Lewis acid catalyst.It is an electrophilic aromatic substitution.

Mechanism of the aluminum chloride-catalyzed reaction

In the first step, the${\mathrm{Cl}}_2$ attacks the${\mathrm{AlCl}}_3$ .

${\mathrm{Cl}}_2$attacks the${\mathrm{AlCl}}_3$

In the second step, the benzene attacks the product formed in the first step.${\mathrm{AlCl}}_4^{\mathrm{\_}}$and chlorobenzene carbocation is formed, in which the positive charge delocalizes at the 1^st, 3^rd, and 5^th positions. The chloride ion${\mathrm{AlCl}}_4^{\mathrm{\_}}$ of makes a bond with the H of benzene and forms HCl. The other product formed is chlorobenzene.

Mechanism of the aluminum chloride-catalyzed reaction