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(2)O) 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 DeltaH for equilibrium formation of nitronium ion.