Discuss the role of Lewis acids in the preparation of aryl bromides and chlorides in the dark.

(N/A) Lewis acids like $FeX_{3}$ $(X = Cl, Br)$ are used to generate the electrophile,the halonium ion $(X^{\oplus})$,from the halogen molecule $(X_{2})$.
The reaction is as follows:
$X-X + FeX_{3} \rightarrow [FeX_{4}]^{-} + X^{\oplus}$
The electrophile $X^{\oplus}$ then attacks the benzene ring to form a $\sigma$-complex,which subsequently loses a proton to form the aryl halide.
Overall reaction:
$C_{6}H_{6} + X_{2} \xrightarrow{FeX_{3}, \text{dark}} C_{6}H_{5}X + HX$ where $X = Cl, Br$.