The stabilities of Meisenheimer complexes. Part XII. Some kinetic studies of the reactions of aromatic nitro-compounds with sodium sulphite in water

Abstract

Kinetic data are reported for the formation in water of 1 : 1 sulphite adducts from 2,4,6-trinitroanisole and from the picrate ion, and 1 : 2 adducts from these compounds and from picramide (2.4,6-trinitroaniiine) and N-methyl- and NN-dimethyl-picramide. The values of k₂ for formation of the diadducts vary little with substrate structure so that variations in complex stability derive mainly from differences in the values of k_–2. There is no evidence from the kinetic measurements or from ¹H n.m.r. spectra for cis–trans-isomerism in the 1: 2 adducts and it seems likely that one isomer, probably the trans-form, is thermodynamically preferred.