Patent GB-578537-A (GB)
Title: Process for the preparation of metallisable polyazo dyestuffs
IPC: C09B35/40
Filed: 1944-06-23
Abstract: Metallizable polyazo dyestuffs are manufactured by reacting on one molecular proportion of resorcinol in either order with, on the one hand, one molecular proportion of a diazotized aminoazo dyestuff of the general formula <FORM:0578537/IV/1> in which A is the radicle of a diazo- or coupling component, which may contain azo groups but must not contain either diazotizable amino groups or carbon atoms capable of coupling, and in which the nucleus B must contain a hydroxyl group in one of the o-positions to the amino group and may contain other substituents, and, on the other hand, one molecular proportion of an intermediate compound obtainable by coupling one end of a tetrazotized 4 : 41-diaminodiaryl with a 1-hydroxybenzene-2-carboxylic acid. The aminoazo dyestuffs employed as starting materials may be obtained by coupling a diazo compound, which may contain azo groups, but neither free nor acylated amino groups nor carbon atoms capable of coupling, with a 1-hydroxy-2-acylaminobenzene with a free 4-position, or with a derivative thereof, and saponifying the acylamino group; or by coupling a 1-diazo-3-acylamino-4-hydroxybenzene, or a derivative thereof, with a coupling component containing only a single group enabling coupling to take place and containing no free or acylated amino group, and subsequently saponifying.  The products of the invention dye cotton and regenerated cellulose brown shades, the fastness of which may be improved by the action of reagents furnishing metals.  In examples: (1) the aminoazo dyestuff produced by saponifying the dyestuff naphthionic acid --> o-acetylaminophenol is diazotized and coupled with resorcinol, and the product is coupled with the intermediate product from tetrazotized benzidine and salicylic acid; the product dyes cotton red-brown shades, becoming more violetty on treatment with copper sulphate; (2) the o-acetylaminophenol in (1) is replaced by 1-methyl-3-acetylamino-4-hydroxybenzene, the product dyeing cotton red-brown shades becoming brown on treatment with copper salts; (3) the naphthionic acid in (1) is replaced by the monoazo dyestuff of the formula <FORM:0578537/IV/2> to yield a pentakisazo dye which dyes cotton reddish-brown shades, becoming violetty-brown on treatment with copper salts; (4) the aminoazo dyestuff obtained by saponifying the dyestuff sulphanilic acid --> o-acetylaminophenol is diazotized and coupled with resorcinol, and the product is coupled with the intermediate product from tetrazotized 3 : 31-tolidine and 1-methyl-2-hydroxy-3-benzoic acid; the product has similar properties to that of (1); (5) the o-acetylaminophenol of (1) is replaced by 1 - acetylamino - 2 - hydroxybenzene - 5 - sulphonic acid, the product dyeing cotton brown shades becoming violetty on treatment with copper sulphate; (6) the aminoazo dyestuff of (1) is replaced by that produced by saponifying the dyestuff 1-amino-3-acetylamino-4- hydroxybenzene --> 1-phenyl-3-methylpyrazolone-41-sulphonic acid; the product dyes cotton yellowish-brown shades, the fastness to light and to washing being improved by treatment with copper salts.  The properties of further tetrakisazo and pentakisazo dyestuffs are shown in a table.  1-Acetylamino-2-hydroxybenzene-5-sulphonic acid is obtainable by stirring an aqueous solution of sodium 1-amino-2-hydroxybenzene-5-sulphonate with acetic anhydride at room temperature.  The Specification as open to inspection under Sect. 91 comprises also in the table dyestuffs obtained by replacing the aminoazo dyestuff in (1) above by dyestuffs of the formul <FORM:0578537/IV/3> and <FORM:0578537/IV/4> This subject-matter does not appear in the Specification as accepted.