Equilibrium constants for the formation of sulphite addition compounds of aromatic aldehydes

Abstract

The equilibrium concentration of the sulphite Meisenheimer adduct of 1,3,5-trinitrobenzene, formed from potassium sulphite/18-crown-6 and trinitrobenzene, in dimethyl sulphoxide solution, is reduced in the presence of an aromatic aldehyde, with an accompanying decrease in the absorbance of the solution due to the intensely coloured Meisenheimer adduct. Equilibrium constants have accordingly been determined for the formation of the sulphite Meisenheimer adduct of trinitrobenzene and for the formation of a series of substituted benzaldehyde sulphite dianions in dimethyl sulphoxide solution.