GB589146A - Manufacture of azo-dyestuffs - Google Patents

Abstract

Azo dyestuffs are manufactured by coupling an o-hydroxydiazo compound containing at least one sulphonic acid group with a 2-amino-6-alkoxynaphthalene free from further substituents, and, if desired, treating the product with an agent yielding metal. Suitable o-hydroxydiazo compounds are those produced by diazotizing o-aminophenolsulphonic acids which may contain further substituents, e.g. halogen atoms, alkyl or nitro groups. Coupling may be effected in an acid, preferably a weakly acid, medium, and may be accelerated by additions of various kinds, e.g. alcohol, pyridine or sodium acetate. For the metallization there may advantageously be used agents yielding chromium, especially compounds of tervalent chromium, the treatment with which may be conducted in an acid, neutral or alkaline medium, with or without the addition of normal salts, which may be of the kind capable of forming complexes, and of organic solvents such as alcohol or pyridine, and at atmospheric or superatmospheric pressure. The products, especially those containing metal, may be used for dyeing or printing materials consisting of or containing animal fibres, e.g. leather, silk or wool. Examples describe the preparation of the following dyestuffs, and their treatment with a solution of chromium formate: 5- or 6 - nitro - 2 - aminophenol - 4 - sulphonic acid, 4 - nitro - 2 - aminophenol - 6 - sulphonic acid or 2 - aminophenol - 4 : 6 - disulphonic acid --> 2 - amino - 6 - methoxynaphthalene, and 2-aminophenol-4 : 6-disulphonic acid -->2-amino-6-ethoxynaphthalene. In a further example, wool is entered at 50 DEG C. into a dyebath containing the chromium compound of the dyestuff 6 - nitro - 2 - aminophenol - 4 - sulphonic acid --> 2 - amino - 6 - methoxynaphthalene, sulphuric acid and sodium sulphate, which is then heated to boiling, more sulphuric acid is added, dyeing completed at the boil, and the wool rinsed and finished, yielding a yellowish-green shade. The Specification as open to inspection under Sect. 91 comprises generally the coupling of any o-hydroxydiazo compound with any 2-aminonaphthalene capable of coupling in the 1-position and containing at least one etherified hydroxyl group (e.g. an alkoxy group in which the alkyl radical may carry solubilizing substituents), which may be in the ring not containing the amino group, advantageously in a b -position. Glycerine mono-(2-amino-6-naphthyl)-ether is specified as an additional coupling component, e.g. in example (1) above. Reference is also made to the use of the products for colouring plastic masses and lacquers. This subject-matter does not appear in the Specification as accepted.