Patent GB-587110-A (GB)
Title: Manufacture of trisazo-dyestuffs
IPC: C09B35/40
Filed: 1943-08-25
Abstract: Trisazo dyestuffs are manufactured by coupling 1 : 3-dihydroxynaphthalene with, in either order, on the one hand a diazo compound of the aryl series containing a lake-forming group (e.g. a hydroxy, carboxyl, alkoxy or alkoxy-carboxyl group) in o-position to the diazo group, and on the other hand a diazoazo compound obtained by unilateral coupling of a tetrazotized benzidine with an o-hydroxyaryl-carboxylic acid capable of coupling, and, if desired, treating the product in substance, in the dyebath or on the fibre with an agent yielding metal, e.g. chromium, cobalt, iron and especially copper.  The products may be used for dyeing or printing animal fibres and especially cellulosic fibres such as cotton, linen and artificial silk and staple fibre of regenerated cellulose.  The dyeings with the non-metallized dyestuffs may be after-metallized, advantageously by the single-bath process.  In examples, the following diazo compounds are coupled with 1 : 3-dihydroxynaphthalene, which is then coupled with the diazoazo compound from tetrazotized benzidine and salicylic acid: (1) diazotized 2-aminophenol-4-sulphonamide; (2) diazotized 4-chloro- or 4-nitro-2-amino-phenol-6-sulphonic acid; (3) the diazo compound obtained by diazotizing 1 : 3 : 6-trichloro - 2 - aminobenzene - 4 - sulphonic acid and stirring with sodium acetate until the chlorine atom in the 1-position is replaced by a hydroxy group; (4) diazotized 6-nitro-2-aminophenol-4-sulphonic acid; (5) diazotized 2-aminophenol-6-carboxylic-4-sulphonic acid; (6) diazotized 5-nitro-2-aminophenol; (7) diazotized 4-nitro-2-aminobenzoic acid; (8) diazotized 1-amino-2-naphthol-4-sulphonic acid; (9) 6-nitro-1-diazo-2-naphthol-4-sulphonic acid; (10) diazotized 6-nitro-2-aminophenol-4-sulphonamide; (11) the diazo compound from the 2-amino-4-methyl-1-hydroxybenzene with bisulphite; (12) diazotized 2-aminophenol-4-sulphonic acid.  In a further example, cotton is dyed with the product of (3) from a bath containing sodium carbonate and, in the later stages, Glauber salt, and is treated in the same bath with a solution of complex copper tartrate rendered weakly alkaline with sodium carbonate, yielding a brown shade. Specifications 455,274 and 532,261 are referred to.  The Specification as open to inspection under Sect. 91 comprises also the manufacture of other dyestuffs (and their complex metal compounds) in which 1 : 3-dihydroxynaphthalene is used as a coupling component capable of coupling twice, including the diazo dyestuffs described in Specification 587,348.  Reference is made to the use of diazo compounds not containing lake-forming groups, including those obtained by unilateral coupling of a tetrazotized diamine with any coupling component, and of diazo components obtained by coupling a diazo compound with a middle component.  An additional example describes the manufacture of the dyestuffs 41-nitro-4-aminodiphenylamine-21-sulphonic acid --> 1 : 3-dihydroxynaphthalene \sM p-nitraniline or 41-nitro-4-amino-diphenylamine-21-sulphonic acid, which dye leather medium brown and reddish dark brown shades respectively.  This subject-matter does not appear in the Specification as accepted.