Inductive and field effects in aromatic substitution. Part V. Kinetics of nitration of the quaternary salts of diazacyclophanes and of related unbridged ions

Abstract

The rates of nitration of the open-chain ions (I) in aqueous sulphuric acid are compared with those of the corresponding bridged ions (II). The comparison is used to provide evidence on how the substituent effects of the groups –[CH₂]_n˙⁺NR₃ depend on the conformation of the carbon chain. The results indicate that for n 2, the deactivation produced by the nitrogen poles depends more directly on the distance of the poles from the centre of the ring than on the number of carbon atoms in the carbon chain. This is interpreted in terms of the field effect of the pole. For n= 1, there is evidence for additional modes of deactivation but the field effect still appears to be the major factor.