The electrophile in nitration of benzene reaction is NO2+.
Nitration of benzene
In the presence of concentrated sulphuric acid, benzene reacts with concentrated nitric acid to form nitrobenzene at 323-333K. Nitration of benzene is the name for this reaction.
The mechanism for nitration of benzene
Step 1: Nitric acid accepts a proton from sulphuric acid and then dissociates to form nitronium ion.
Step 2: The nitronium ion acts as an electrophile in the process which further reacts with benzene to form an arenium ion.
Step 3: The arenium ion then loses its proton to Lewis base forming nitrobenzene.