Process for the manufacture of symmetric 1:2 chromium complexes of azo dyes

摘要

The present invention relates to a process for the manufacture of 1:2 chromium complexes of metallisable azo dyes, wherein the azo dyes are treated in aqueous solution at pH 7 to 9 with at least the stoichiometric amount of a chromium complex, and, in the course of the chroming, the reaction medium is acidified once or repeatedly to a pH of 6 or less and subsequently brought back again to pH 7 to 9.