Ciba-Geigy Corporation

Walter Iff

Daniel Parisot

Hans Schaller

The invention relates to a process for the preparation of asymmetrical 1:2 chromium complex dyes of not less than 90% purity and containing at least one water-solubilizing group, which process comprises reacting a mixture of two metallizable azo dyes that contain different diazo components and different coupling components, or a mixture of a metallizable azo dye and a metallizable azomethine dye, in the molar ratio of 0.85:1.0 to 1.2:1.0, with the proviso that only one of said two mixture components contains at least one water-solubilizing group, with a chromium donor, under pressure and at a temperature above 100.degree. C. and in the pH range from 0 to 2, and subsequently carrying out further reaction in a weakly acid, neutral or weakly alkaline pH range, utilizing a single vessel for all steps. The dyes obtained by the process of the invention are particularly suitable for dyeing wool or polyamide materials.

Preparation of 1:2 chromium complex azo dyes asymmetrically substituted

The invention relates to a process for the preparation of asymmetrical 1:2 chromium complex azo dyes of not less than 90% purity and containing at least one water-solubilizing group, which process comprises reacting a mixture of two metallizable azo dyes that contain identical diazo components or identical coupling components, in the molar ratio of 0.85:1.0 to 1.2:1.0, with the proviso that only one of said two azo dyes contains at least one water-solubilizing group, with a chromium donor, under pressure and at a temperature above 100.degree. C. and in the pH range from 0 to 2, and subsequently carrying out further reaction in a weakly acid, neutral or weakly alkaline pH range, utilizing a single vessel for all steps The dyes obtained by the process of the invention are particularly suitable for dyeing wool or polyamide materials.

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Craponne, France

Walter Iff