Electrophilic aromatic substitution. Part X. The kinetics and mechanism of nitration of some anilides and aromatic ethers in sulphuric acid and in acetic anhydride, with particular reference to the existence of a special mechanism for ortho-nitration in the latter medium

Abstract

Rate constants for the nitration of various anilides and aromatic ethers in sulphuric acid and in acetic anhydride are presented. These results, together with those of protonation studies in sulphuric acid, enable the reacting species of the aromatic substances to be identified. The observed changes in reactivity and in the ortho; para ratios with changes in the reaction medium are discussed and evidence is presented in support of the view that a special mechanism for ortho-nitration of some substrates operates in acetic anhydride. In the light of the present results the criteria which have been used previously to support a special mechanism for ortho-nitration are critically discussed.