Colour and constitution of the nitro- and dinitro-p-phenylenediamines and their N-methyl derivatives

Abstract

The syntheses of new violet to blue-green dinitro-p-phenylenediamines are described. The visible absorption spectra are compared with those of the mononitro-analogues, and the light absorption characteristics have been examined by the PPP–MO procedure. Good agreement between the theoretical predictions and experiment was observed for those derivatives with minimal steric crowding. Bathochromic shifts of up to 100 nm result from the introduction of a second nitro-group into the nitro-p-phenylenediamine chromogen.