Electronic and steric effects in the SNAr substitution reactions of substituted anilines with 2,4-dinitrophenyl 2,4,6-trinitrophenyl ether in acetonitrile.

Abstract

Rate measurements are reported for the reactions of 12 ring-substituted anilines with 2,4-dinitrophenyl 2,4,6-trinitrophenyl ether (1) in acetonitrile. Formation of the products, the correspondingly substituted 2,4,6-trinitrodiphenylamines, occurs without the observation of intermediates in detectable amounts by both base-catalysed and uncatalysed pathways and Hammett value were determined for these processes. The results show that although substituents at the 3- or 4-positions of the anilines have only small steric effects, alkyl substituents at the 2-position may result in considerable reductions in reactivity. These effects are more pronounced for the base-catalysed pathway and in 2,6-dimethylaniline the uncatalysed pathway takes all the reaction flux. In the case of the 2-fluoro substituent the electronic effect, strong inductive electron withdrawal, is dominant over steric effects.