GB490965A - Manufacture of azo-dyestuffs - Google Patents

Abstract

Mordant dyeing disazo dyes are made by coupling J acid first in a weak acid medium and then in an alkaline medium with two molecular proportions of diazotized o-aminophenols or o-aminonaphthols at least one of them having a hydroxy group and a carboxy group in o-position to one another. They may be used for chrome printing and are of particular value in the form of their complex metal compounds, being suitable for dyeing and mordant printing on cotton, silk, and regenerated cellulose, e.g. by the processes described in Specifications 26460/12, 318,469, [both in Class 2 (iii)], 319,457, [Class 15 (ii)], and 435,701. The metal compounds may be obtained according to the process described in Specification 26460/12. Di-and trivalent metal compounds, e.g. iron compounds may be used and more than one metal may be introduced into the dyestuff. In examples, the dyestuffs 2 - amino - 1 - hydroxybenzene - 6 - carboxylic acid --> (acid) J acid \sM (alkaline) 1-amino-2-oxy-3-nitrobenzene-5-sulphonic acid; 2-amino-4-sulpho - 1 -hydroxybenzene-6-carboxylic acid --> (acid) J acid \sM (alkaline) picramic acid or 2 - amino - 4 - sulpho - 1 - hydroxybenzene-6-carboxylic acid or 1-amino-2-oxy-3-nitrobenzene-5-sulphonic acid are boiled with an agent yielding chromium, e.g. chromium acetate or sulphate. The products yield greyish shades when printed on cotton. Specifications 8575/03, 1581/04, [both in Class 2], 29567/13, [Class 2 (iii)], 351,400, and 357,543 also are referred to. The Specification as open to inspection under Sect. 91 states that of the two diazo compounds which are coupled as above with J acid at least one must be derived from an o-aminiphenol or o-aminonaphthol and at least one must contain the usual mordant groups such as the salicylic group. In examples and a table, dyes from the following additional components are specified: (acid coupling) p-aminosalicylic acid, p-amino-o-sulphosalicylic acid, 1 - amino - 2 - oxy - 3 - nitrobenzene - 5-sulphonic acid, 3 - amino - 4 - sulphobenzene azosalicylic acid, o - amino - p - chlorsalicylic acid, 1 - hydroxy - 2 - amino - 6 - nitrobenzene-4 - sulphonic acid, 1 - hydroxy - 2 - amino - 4-chlorobenzene-6-sulphonic acid; (alkaline coupling) 1 - amino - 2 - oxy - 3- or 4-nitro - 5-chlorobenzene, p-aminosalicylic acid, 1-oxy-2-amino - 4 - chlorbenzene - 6 - sulphonic acid, 1 - hydroxy - 2 - amino - 6 - methyl - 4 - nitrobenzene, 5 - nitro - 2 - aminophenol, 1 - hydroxy - 2 - amino - 4 - methyl - 6 - nitrobenzene, 1 - hydroxy - 2 - amino - 4 - nitrobenzene-6 - sulphonic acid. Chromium lactate and copper sulphate are also specified as agents yielding metal. Some of the chromium compounds may be boiled with caustic soda to give more soluble products. This subject-matter does not appear in the Specification as accepted.