Marked deviations from the additivity principle in the products of nitration of substituted anilinium ions

Abstract

Product compositions have been determined for the nitration of several substituted anilinium ions activated by a methoxy-group or by two methyl groups. Kinetic studies have been carried out on two compounds with a methoxy-substituent. The results have been shown to deviate markedly from those predicted by the additivity principle but to be understandable on the assumption that the substituents exert independent directing effects which are not necessarily the same as those shown in the corresponding monosubstituted benzenes. In particular, the nitrogen pole appears to deactivate all positions in the ring to a very similar extent and the methoxy-group appears to be much more ortho-directing than is observed in the nitration of anisole. These results are shown to accord with other results in the literature and to lead to a reassessment of the apparently anomalous orientation of electrophilic substitution in meta-nitroanisole.