Kinetic and equilibrium studies on σ-complexes of 2,4,6-trinitroanisole and picrylsulphonate with sulphite ion in aqueous solution

Abstract

The reactions of 2, 4 , 6-trinitroanisole (TNA) and picrylsulphonate with sulphite ion in aqueous solution take place to give intensely colored σ-complexes. Kinetic studies on the formations of these complexes have been carried out by the stopped-flow method in the temperature range, 15.0～30.0℃. The respective rate constants for the formation and the decomposition (reverse reaction) of σ-complexes were well consistent with the results of the separate equilibrium study. The effect of ionic strength on the anion-anion reaction was well explained by taking into account of the Debye-Huckel equation. Kinetic and thermodynamic parameters were determined and compared with the previous data on the interaction of 1, 3, 5-trinitrobenzene with sulphite ion, and with the results of methoxide attack to TNB and TNA.