91Ó°ÊÓ

Resonance structures exhibit variation in the lone pair position or bonding electrons. The resonance hybrid’s stability depends on the stable resonance forms that contribute to the resonance hybrid.The position of atoms in the resonance structures does not show variation.

The resonance structures for the intermediates from the reaction of an electrophile at the ortho, meta and para position of nitrobenzene can be shown as:

Resonance structure for ortho, meta and para attack

One resonance form for the ortho and para attack is least stable as they have positive charges on the nearby atoms. Thus only two forms are stable. For the meta attack, all the three forms are stable. Hence, meta intermediate is more favored and the nitro group is a meta director.