Title: Process for the manufacture of chromium complexes from metallizable azo or azo methine dyes

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Abstract: A process is described for the manufacture of chromium complexes of metallizable dyes in the form of solid dyestuff powders of low salt to salt-free content, or of concentrated solutions of low salt or salt-free content in which a metallizable dye, or a mixture of metallizable dyes, in an organic solvent which is immiscible or sparingly miscible with water, or reacted with a chromium compound, in the course of which any water which is liberated is removed by azeotropic distillation, and the resulting chromium complex, provided it is a 1:1 complex, is then optionally reacted in the presence of a base with a further mol of a metallizable dye, or of a colorless, complexforming compound, then isolated from undissolved constituents, and the resulting dye solution of low salt or salt-free content is optionally concentrated or evaporated to dryness, whereby it is possible the manufacture of 1:1 or 1:2 chromium complexes without the handicap of effluent pollution, and to isolate the dyes without using salt. The dyes obtained are especially suitable for the manufacture of concentrated solutions without the necessity of having to increase the solubility by means of extenders.


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