Benzene reacts with ${\text{CH}}_3\text{Cl}$ in the presence of anhydrous ${\text{AlCl}}_3$ to form:

This is the Friedel-Crafts Alkylation reaction. Benzene reacts with an alkyl halide in the presence of a Lewis acid (${\text{AlCl}}_3$) to form an alkylbenzene.${\text{C}}_6{\text{H}}_6+{\text{CH}}_3\text{Cl}\stackrel{{\text{anh. AlCl}}_3}{\to }{\text{C}}_6{\text{H}}_5{\text{CH}}_3+\text{HCl}$.The product is Toluene.