Electrophilic aromatic substitution. Part VII. A critical re-examination of the reactivity of toluene towards nitration with acetyl nitrate in acetic anhydride, as determined by the kinetic and competition methods

Abstract

Previously reported applications of the competition method for determining the relative rate of nitration of toluene and benzene are discussed critically. The kinetics of nitration of toluene and benzene with solutions of acetyl nitrate in acetic anhydride, and the effect upon these of added acetic acid have been studied. Acetic acid accelerated the rate of nitration of both toluene and benzene when the initial concentration of nitric acid was <1 mol l^–1, and, in the case of benzene, reduced the kinetic order with respect to the initial concentration of nitric acid from ca. three to ca. two. The kinetic method gave a relative rate of nitration of toluene and benzene of 50 ± 6, whilst the value determined by competition was 38 ± 5. The discrepancy between these and earlier results is discussed.