Explain the preparation of aryl halides from aromatic hydrocarbons.

(N/A) Haloarenes are prepared by the electrophilic substitution of arenes. Aryl chlorides and bromides are prepared by the chlorination and bromination of arenes in the presence of Lewis acid catalysts like iron or iron$(III)$ chloride $(FeCl_3)$.
The reaction of toluene with $X_2$ (where $X = Cl, Br$) in the presence of $Fe$ in the dark yields a mixture of $o$- and $p$-halotoluenes. These isomers can be separated due to the large difference in their melting points.
Direct iodination of arenes is reversible and requires the presence of an oxidizing agent like $HIO_3$ or $HNO_3$ to oxidize the $HI$ formed,thereby driving the reaction forward:
$5 HI + HIO_3 \rightarrow 3 I_2 + 3 H_2O$
Fluoroarenes are not prepared by this method because the high reactivity of fluorine is difficult to control.