Patent GB-869842-A (GB)
Title: Metal-containing monoazo dyestuffs
Filed: 1959-03-11
Abstract: Metal-complex compounds of monoazo dyes of the formula:- <FORM:0869842/IV(c)/1> wherein Ac is an acyl radical of a carboxylic acid, R is an alkyl radical containing 1-4 carbon atoms and X is a hydroxyl group or a radical convertible into hydroxyl under conditions of metallization, are claimed as new compounds.  The monoazo dyes may be obtained by combining diazotized amines of formula:-  <FORM:0869842/IV(c)/2> with coupling components of formula:-  <FORM:0869842/IV(c)/3> Coupling is preferably carried out under alkaline conditions and in presence of promoters such as pyridine and its homologues and formamide.  Examples of amines which may be used in forming the dyes are 6-nitro-4-acetylamino-2-amino-1-hydroxybenzen and the corresponding 4-propionylamino compound and their esters or ethers.  As coupling components there may be used 1-methyl, ethyl, and propyl-sulphonylamino-7-hydroxy-naphthalenes.  The monoazo dyes are water-soluble when in the form of their alkali metal salts and they may be used for dyeing wool by a single bath chrome process, greenishblue shades being obtained.  The metal-complex compounds may be produced in substance, and preferably processes leading the formation of 1 : 2 complexes are used.  Metallization may be effected in a neutral to alkaline aqueous medium.  It is preferred to form chromium or cobalt complexes.  Chroming may be effected with alkali metal chromates in the presence of reducing carbohydrates, and cobalting with salts of bivalent cobalt or complexes of trivalent cobalt.  Apart from the reaction of monoazo dyes of the same composition, mixtures of monoazo dyes may be metallized, one having the stated general formula, the other being an optional metallizable monoazo dyestuff.  Mixed chromium complex compounds may also be obtained by reacting the 1 : 1 chromium complex of one dyestuff of the defined type with a different metal-free dyestuff.  The complexes dye wool, and other fibres of similar dyeing properties, from neutral baths or from organic acid baths.  Chromium complexes give greenish-blue shades and cobalt complexes give reddish-blue shades. In examples, the dye 6- nitro- 4- acetylamino- 2- amino- 1- hydroxybenzene --> methylsulphonylamino-7-hydroxynaphthalene is dissolved in hot alkaline water and treated with a solution of potassium bichromate and glucose to form the chromium complex of the dye.  The cobalt complex is obtained by treating a solution of the dye with a solution of cobalt sulphate, ammonia, and hydrogen peroxide.  A mixed chromium-complex dye is obtained by forming a mixed aqueous solution of the specified monoazo dye and a dye of the formula:-  <FORM:0869842/IV(c)/4> and treating the solution with a solution of potassium bichromate and glucose.  A mixed complex is obtained by mixing a solution in pyridine of a monoazo dye of the specified general formula with a 1 : 1 chromium complex of the monoazo dyestuff:-  <FORM:0869842/IV(c)/5> A mixed complex is obtained by treating, with a solution of potassium bichromate and glucose, an alkaline solution containing a mixture of the following dyes:-2-amino- 1-hydroxybenze- 4-sulphonamide --> 2-hydroxynaphthalene, 4-nitro-2-amino- 1-hydroxybenzene --> 1-acetylamino-7-hydroxynaphthalene, and 4-acetylamino- 6-nitro-2-amino- 1-hydroxybenzene --> 1-methylsulphonylamino- 7-hydroxynaphthalene.  Specifications 755,853 and 758,016 are referred to.