Preparation of dyes which contain sulfonic acid groups and have a low electrolyte content

US4560745A · kind A · utility

Assignee

• BASF SE

Inventors

• Volkmar Weberndoerfer · Mannheim, DE
• Friedrich Brunnmueller · Ludwigshafen, DE
• Manfred Eisert · Ludwigshafen, DE
• Rudolf Bermes · Ludwigshafen, DE

Key dates

• Filing date: May 12, 1981
• Grant date: Dec 24, 1985
• Expiry date: May 12, 2001

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B67/0096
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of dyes which contain sulfonic acid groups and have a low electrolyte content, wherein an aqueous solution or suspension, which may or may not contain inorganic salts, of the dye containing sulfonic acid groups is PA1 (a) mixed with an amount, equivalent to the said dye, of a non-emulsifying, water-insoluble amine of a total of 12 to 40 carbon atoms, which forms, with the said dye, a salt which is sufficiently lipophilic for it to separate spontaneously from the aqueous phase, PA1 (b) the pH is brought to <5 with an acid and the batch is mixed thoroughly, PA1 (c) the two resulting phases of different density are separated, and PA1 (d) the phase which consists of the lipophilic ammonium salt of the dye is mixed, with or without prior washing with water, with a water-soluble base whose sulfonate salt is to be prepared, and with water, the resulting phases are separated, and the salt is left in the aqueous solution or is isolated therefrom.