The nitrous acid catalysed nitration of naphthalene. Evidence for a kinetic term that is second order with respect to the aromatic compound

Abstract

The kinetic equation for the nitrous acid catalysed nitration of naphthalene in aqueous mixtures of sulphuric acid and acetic acid has at least two kinetic terms: one first order with respect to naphthalene and one second order with respect to naphthalene. The orders with respect to nitrous acid and nitric acid vary with the conditions in the way characteristic of the electron transfer mechanism of this reaction. The second-order term with respect to naphthalene is considered to derive from the formation of the dimeric radical cation (ArH)2+•. The acidity dependence of the rate coefficients and the absence of a normal isotope effect in the reaction of naphthalene-d8 are consistent with this interpretation. Keywords: naphthalene, nitration, nitrous acid.