How does H2SO4 help in the formation of NO2 + from HNO3 during the electrophilic substituion reactions ???

Hi Swapnil,

Conc H₂SO₄ is more acidic than HNO₃. Hence in this reaction HNO₃ will act as if it were a base, acception H⁺ from H₂SO₄, becoming H2NO3⁺...... now this with conc H2SO4 (also a dehydrating agent will absorb water) -----> H2O + NO2⁺

That is how it is generated in the mixture.

Hope it helps.

Best Regards,

Ashwin (IIT Madras).

Highly concentrated H₂SO₄ protonate Con. Nitric Acid and eliminate water molecule to generate nitronium ion which attach benzene ring via. electrophilic substitution reaction and forms nitro benzene.