Reactions of cerium(IV) ammonium nitrate with aromatic compounds in acetonitrile. Part 2. Nitration; comparison with reactions of nitric acid

Abstract

The nitration of benzene and a number of alkylbenzenes by cerium(IV) ammonium nitrate in acetonitrile shows the same intra- and inter-molecular selectivity as nitration with nitric acid under the same conditions but the extent of the other products formed in the two sets of reactions is very different. Nitration, by cerium(IV) ammonium nitrate (but not side-chain substitution) is suppressed by the addition of water. The results suggest that these nitration reactions by cerium(IV) ammonium nitrate occur through the intermediate formation of a nitronium ion from the cerium(IV) complex but the order with respect to the aromatic compound shows that this nitronium ion must then be formed in the presence of the aromatic substrate as a ‘ spectator’. The relative reactivities with respect to benzene in the nitration of anisole and naphthalene are much greater than those observed in nitration by nitric acid and, with both, the isomer proportions are also anomalous.