GB609301A - Manufacture of disazo-dyestuffs - Google Patents

Abstract

Disazo dyes are obtained by coupling tetrazotised 3 : 31 - dihydroxy - 4 : 41 - diaminodiphenyl with 2 mols. of the same or different coupling components (other than a 1-hydroxynaphthalenesulphonic acid carrying an auxochromic group in 8-position) in a medium rendered alkaline with a hydroxide of an alkali metal, e.g. sodium or potassium, or of an alkaline earth metal, e.g. calcium, magnesium, strontium or barium, or of ammonium. Specified coupling components are 2 : 5 : 7- and 2 : 8 : 6-aminonaphtholsulphonic acids, 2 : 6-naphtholsulphonic acid and 2 : 3 : 6-naphtholdisulphonic acid. The products are suitable for dyeing cellulose fibres, e.g. of cotton or regenerated cellulose, or animal fibres, e.g. wool, silk or leather and may be treated in substance, in the dyebath or on the fibre, with agents yielding metal, e.g. copper, chromium, iron, nickel or cobalt. The metal compounds produced in substance may be incorporated in nitrocellulose lacquers, artificial resins and spinning masses. In examples, tetrazotised 3 : 31 - dihydroxy - 4 : 41 - diaminodiphenyl is coupled (1) in aqueous potassium hydroxide solution, (2) in aqueous calcium hydroxide solution with 2 : 5 : 7-aminonaphtholsulphonic acid (2 mols.) to obtain a product giving fast blue after-coppered dyeings on cotton, (3) in aqueous potassium hydroxide solution with 2 : 3 : 6-naphtholdisulphonic acid (2 mols.) to obtain a similar product, (4) in aqueous calcium hydroxide solution with 2 : 8 : 6-aminonaphtholsulphonic acid (2 mols.) to obtain a similar product. In an example of the dyeing process, wetted-out cotton is introduced into an aqueous dyebath at 50 DEG C. containing the dyestuff obtained in (1) above and sodium carbonate, the temperature is raised to 95 DEG C. and, after addition of Glauber salt, is so maintained for 1 hour; the temperature is then allowed to fall to 80 DEG C. and sodium copper tartrate added, whereupon coppering is effected for 1/2 hour at 80-90 DEG C. and the cotton is rinsed and, if desired, soaped. Specifications 455,274 and 609,302 are referred to.