Hydrocarbons

GENERAL MECHANISM Benzene undergoes electrophilic substitution because of its exposed π electrons. In case of electrophilic substitution, benzene resembles alkene as the site of electrophilic attack in alkene is π bond only. But benzene also differs from alkene as the latter undergoes addition reaction and benzene prefers substitution rather than addition. In step 1, the electrophile attacks the π system of benzene to form a non-aromatic cyclohexadienyl carbocation or arenium ion.