The reaction of phenol with concentrated nitric acid in the presence of sulphuric acid, however, is a tri-nitration reaction. the product is 2,4,6-trinitrophenol (commonly called picric acid ). If phenol is treated with dilute nitric acid, mono or disubstituted nitrophenols are formed. o-nitrophenols are more stable than p-nitrophenols due to intramolecular hydrogen bonding.
