Question

Why preparation of aryl iodide by electrophillic substitution requires presence of an oxidising agent? why can arylflouride not be prepared by this method?

Answer 1

Reactions of arenes with iodine are reversible in nature. So, aryl iodides are prepared in the presence of an oxidising agent such as $HN{{O}_{3}}$, HIO4, etc., in order to oxidise the HI formed during iodination.

Answer 2

beacuse they are reversible in nature while electophiles substances are loving agents