Electrophilic aromatic substitution. Part IX. The kinetics of nitration of benzene and some methylbenzenes in aqueous acetic acid and in acetic anhydride, with observations on limiting rates of nitration and on M.O.-theoretical treatments of nitration rates

Abstract

The kinetics of the nitration in aqueous acetic acid and in acetic anhydride of naphthalene, 1-methylnaphthalene, benzene, toluene, m-xylene, and mesitylene are reported and discussed. The observed rate constants for the last two compounds fall far short of those calculated on the basis of the Additivity Principle, and in this respect the results resemble closely previous ones for nitration in nitromethane, in sulpholan, and in aqueous sulphuric acid. It is argued that in all of these media activating substituents lead to a limiting rate which is probably the rate of encounter of the aromatic molecules with the nitrating species. The comparison of these and similar data with the results of M.O.-theoretical calculations is critically discussed.

Anomalous behaviour of o-xylene and p-xylene when they are nitrated in acetic acid is also reported.