Q.
Benzene cannot be iodinated with I2 directly. However, in presence of oxidants such as HNO3 , iodination is possible. The electrophiles formed in the case is:
In the presence of oxidising agents such as HNO3 direct, iodination of benzene is possible. The electrophiles formed in this case is [I+] .
Iodination reaction is reversible reaction. Nitric acid is oxidising agent which makes reaction irreversible. H++HNO3+21I2→ Iodine cation I++NO2+H2O