SOME UNCONVENTIONAL PATHWAYS IN AROMATIC NITRATION

This review deals with a group of reaction paths for nitration in homo geneous solution associated particularly with the species NO+, NO2., N O3. and N2O5. Studies on the properties of these and some related nitr ogen compounds are considered first. with special reference to the int eraction of these species with aromatic compounds. Evidence on the ele ctron transfer mechanism of nitrous acid catalysed nitration, on nitra tion by nitrogen dioxide in organic solvents, on nitration by preforme d dinitrogen pentoxide, and on ozone mediated nitration by nitrogen di oxide is then considered. The emphasis is on the mechanisms of these r eactions when carried out using thermal rather than photochemical proc esses. Some interesting features of these mechanisms are then examined , with particular reference to the oxidation of aromatic substrates by NO3. and possibilities for further work.