GB778233A - New tetrakisazo-dyestuffs and process for making them - Google Patents

Abstract

The invention comprises dyestuffs of formula <FORM:0778233/IV(b)/1> where R1 is a diphenyl residue bound in the 4 and 41 positions to the azo linkage and containing in the 3, 31 positions an - O - O - CH2-COOH group or a COOH group and R2 and R3 are residues of naphthol sulphonic acids bound to - N=N - R1 in a position vicinal to the OH group and each containing a single sulphonic acid group bound to the naphthalene nucleus. The dyestuffs may be made by coupling a tetrazo compound of an appropriate diaminodiazo - dyestuff with 8 - oxyquinoline advantageously tetrazotization is effected by the indirect method and coupling in an alkaline medium optionally with the addition of a compound such as pyridine or alcohol. Preferably the 8 - oxyquinoline is coupled in a finely divided state e.g. as precipitated by alkali from a hydrochloric acid solution, before or after mixing with the tetrazocompound. The diazo dyestuffs are made by coupling the necessary tetrazotized diphenyl derivative with an appropriate naphthol sulphonic acid generally in an alkaline medium and advantageously a solution of the tetrazo compound is run into an alkaline solution of the sulphonic acid. The carboxymethoxy group is specified as a 3, 31 - substituent in the diphenyl compounds. Specified naphthol sulphonic acids are 2 - (41 - aminophenylamino) - 5 - naphthol - 7, 31 - disulphonic acid, <FORM:0778233/IV(b)/2> and 2 - amino - 5 - naphthol - 7 - and - 8 - naphthol - 6 - sulphonic acids the last two acids being preferred. Mixtures of sulphonic acids may be used. The dyestuffs dye wool, silk or leather and especially cellulose-containing materials such as cotton, linen and regenerated cellulose. They may be converted into metal compounds on the fibre, in substance or in the dyebath. Metallization, e.g. coppering may be effected as in Specification 455,274 [Group IV] and after-treatment with an aqueous solution containing a basic formaldehyde condensation product as in Specification 619,969 may be effected. Cellulose fibres yield coppered dyeings in navy blue, grey or black shades. Examples are provided of the preparation of the dyestuffs by the use of certain of the above specified components the products being used to give coppered dyeings on cellulosic materials.