The nitrous acid catalysed nitration of naphthalene and its derivatives. Part 2. The kinetics of the reactions in methanesulphonic acid and trifluoroacetic acid

Abstract

The kinetics of the nitrous acid catalysed nitration of naphthalene in aqueous trifluoroacetic acid and in mixtures of methanesulphonic acid and acetic acid involve a term that is second-order with respect to the aromatic substrate. The second-order term becomes predominant when the concentration of naphthalene exceeds 0.01 mol dm^–3. This term is absent in the corresponding reaction of 1,5-dimethylnaphthalene. The difference between the kinetic forms of the two reactions is attributed to the known difference in the ease of formation of the dimer radical cations {(ArH)₂˙⁺} from the two aromatic compounds. The difference in the kinetic forms also implies that the relative reactivity of these substrates in nitrous acid catalysed nitration must depend on the initial concentrations.