Interactions of 1,2,3,5- and 1,2,4,5-tetranitrobenzene with some nucleophiles in protic solvents

Abstract

In the presence of hydroxide ion or sulphite ion in water, or ethoxide ion in ethanol, 1,2,3,5-tetranitrobenzene gives red complexes which are shown, from 1H n.m.r. measurements, to result from covalent addition of the nucleophile at a hydrogen-carrying ring carbon. The equilibrium constant for the formation of the hydroxide adduct has the value 2·4 × 104 l. mole–1. The solutions are not stable and replacement of the nitro-group at C-2 occurs quickly. The rate constants have been measured. In contrast 1,2,4,5-tetranitrobenzene reacts with hydroxide to give 2,4,5-trinitrophenol without the production of colour. With ethoxide or sulphite ions coloured species are produced whose structures are discussed.