question_answer 77)

Aryl chlorides and bromides can be easily prepared by electrophilic substitution of arenes with chlorine and bromine respectively in the presence of Lewis acid catalysts. But why does preparation of aryl iodides require presence of an oxidising agent ?

Answer:

  p-Dibromobenzene being symmetrical fits in the crystal lattice better than the o-isomer and hence has higher melting point than the o-isomer.