Kinetics and mechanism of nitrosation of toluene, o-xylene, and m-xylene in trifluoroacetic acid, or in acetic-sulfuric acid mixtures, under nitric oxide

The title reactions give good yields with m-xylene, and modest yields with toluene and o-xylene which are successfully directly nitrosated for the fir st time. The advantages of purging with nitric oxide are demonstrated and d iscussed. The kinetics have been successfully interpreted in terms of a mec hanism in which both the aromatic substrate and the nitrosoaromatics form, reversibly, complexes with nitrosonium ion. The nitrosoaromatics are unstab le under the acid conditions and the method is successful only because of t he protective complexation with the nitrosonium ion.