Kinetics and Mechanism of the Nitration of Chlorobenzene with Nitric Acid

The rate of homogeneous nitration of chlorobenzene with 70-90% nitric acid is proportional to the chlorobenzene concentration and activity of nitric acid. The existence of linear correlations between the rate constants k _2ap and the acidity function -H and between logk ^* _2ap values (calculated using NO₂ ⁺ concentration) and the acidity function -(H _R + logaH ₂O) indicates that the nitrating species is nitronium ion generated by reaction of H₃O⁺ with nitric acid monohydrate. Increase in the energy of activation with rise in water concentration is explained by increase of H for equilibrium formation of nitronium ion.