process for the production of triphendioxazinverbindungen

摘要

The triphendioxazine compounds of the general formula (I) CHEM in which the rings labelled A in positions 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- carry a linearly or angularly fused heterocyclic ring containing at least one nitrogen atom which is substituted or unsubstituted, with the proviso that compounds with only unsubstituted nitrogen atoms and symmetrically disubstituted compounds with C1-2alkyl and unsubstituted phenyl substituents are excluded, are outstanding pigments and are notable over the closest comparable pigments in particular for better migration, light and solvent fastnesses, better heat stability and enhanced colouring power and also better dispersibility and capability to be brought into pigment form. The invention also relates to a process for preparing these triphendioxazine compounds which is characterized by a cyclization step conducted in the presence of manganese dioxide and concentrated sulphuric acid.