New aqueous solutions concentrated of brightening agents benzimidazolium, to the to prepare and their use for the optical brightness of organic materials

摘要

The invention relates to N-acyl-o-phenylenediamines of the formula IMAGE wherein A is a colorless carbocyclic or heterocyclic aromatic radical and each of R1 and R2 independently is an alkyl, alkenyl or phenyl radical which is unsubstituted or substituted by non-chromophoric groups, but only one of R1 and R2 can be phenyl, and the ring B can also be substituted by non-chromophoric groups. The invention also relates to processes for the manufacture of these compounds, their use for whitening man-made organic material, their conversion into benzimidazolium compounds as well as stable, concentrated aqueous solutions of such compounds, processes for their manufacture and their use for whitening man-made organic material.