Patent GB-643535-A (GB)
Title: Manufacture of new tetrakisazo-dyestuffs
IPC: C09B33/28
Filed: 1948-01-08
Abstract: Tetrakisazo dyestuffs are manufactured by coupling a diazo compound of an amine of the general formula R1-N=N-R2-NH2 (wherein R1 represents a benzene residue containing a hydroxy and a carboxyl group in o-position to one another and R2 represents a benzene residue in which the azo group and the diazotizable amino group are in p-position to one another and an alkoxy group is present in o-position to the latter) in an alkaline medium (advantageously one rendered alkaline with an alkali carbonate, if desired with the addition of an agent favouring coupling or an acid-binding agent, e.g. pyridine or ethanolamines) with a disazo dyestuff of the general formula <FORM:0643535/IV (c)/1> (wherein R3 represents a benzene residue containing a hydroxy and a carboxyl group in o-position to one another, and R4 represents a benzene residue in which the azo groups are in p-position to one another).  The products are suitable for dyeing animal fibres (e.g. wool, silk and leather) and especially for dyeing or printing cellulosic materials (e.g. cotton, linen, or artificial silk or staple fibres of regenerated cellulose), and may be converted in substance, in the dyebath or on the fibre into complex metal (e.g. copper, chromium, iron, nickel or cobalt) compounds, e.g. dyeings or prints with the metal-free dyestuffs may be after-treated with solutions of a water-soluble copper compound and a basic condensation product of formaldehyde with a compound containing at least one grouping <FORM:0643535/IV (c)/2> The diazo components R1-N=N-R2-NH2 are obtainable by coupling a diazotized aminosalicylic acid, which may contain further substituents such as halogen atoms or alkyl, alkoxy, nitro or sulphonamide groups (e.g. 6 - amino - 4 - nitrophenol - 2 - carboxylic acid or especially 6-methyl-, 6-chloro- or 6-nitro-4-aminophenol-2-carboxylic acid) with a 2-alkoxyaniline unsubstituted in the 4-position but optionally substituted elsewhere (e.g. 2-ethoxy-or 2-methoxy-anilines which preferably contain in the 5-position a substituent favouring coupling, such as an alkyl or alkoxy group, or which in the absence of such a substituent are advantageously used in the form of their o -methane-sulphonic acids); or in some cases (e.g. for preparing 4-amino-31-methoxy-41-hydroxy - 1 : 11-azobenzene-31-carboxylic acid-6-sulphonic acid) by coupling a diazotized 3-alkoxyaniline, containing in the 4-position a group convertible to NH2 (e.g. a nitro or acylamino group), with an o-hydroxybenzoic acid capable of coupling, and then converting to NH2 the group so convertible.  The disazo dyestuffs serving as coupling components are obtainable by coupling 2 : 5 : 7-aminonaphthalsulphonic acid in an acid medium with a diazo compound of an amine H2N-R4-N=N-R3 (e.g. 4-amino-41-hydroxy-1 : 11-azobenzene-31-carboxylic acid or its 51-chloro-, 51-methyl-, 51-nitro, 2-methyl-5-methoxy-51-nitro-, 2-methyoxy-, 2 : 5-dimethoxy-, 2-methoxy-5-ethoxy- or 2-methyl-5-methoxy-derivatives), which are obtaniable by the same methods as R1-N= N-R2-NH2 (except that R4 need not contain an alkoxy group).  Examples describe the use of certain of the foregoing components, and the dyeing of cotton with one of the products from a bath containing sodium carbonate and sulphate, with after-treatment in a bath containing (a) copper sulphate and acetic acid, or (b) complex copper-sodium tartrate, or (c) cupric tetramine acetate, sodium carbonate and a water - soluble formaldehyde - dicyandiamidine condensation product.  Specifications 455,274 and 619,969 are referred to.