Patent GB-684646-A (GB)
Title: Manufacture of metal-free azo-dyestuffs and of azo-dyestuffs containing chromium
IPC: C09B45/16
Filed: 1950-11-10
Abstract: The invention comprises (1) dyestuffs of the formula <FORM:0684646/IV (c)/1> which are free from sulphonic acid and carboxylic groups; R is a benzene residue containing a hydroxy group oto the azo linkage and also a sulphonamide group; (2) chromium compounds of the above dyestuffs containing less than one atom of chromium per molecule of dyestuff; and (3) chromium compounds containing two or more dyestuffs of the above formula, there being a sulphonamide group in at least one of the residues R and the ratio of chromium atoms to dyestuff molecules being less than 1 : 1, preferably 1 : 2.  The above compounds are made by coupling a diazotized o-aminophenol-sulphonamide with a 1-acylamino-7-naphthol (both components being free from sulphonic acid and carboxylic groups) and chroming the product alone or together with another monoazo dyestuff of the type o-aminophenol --> 1-acylamino-7-naphthol (both components being free from sulphonic acid and carboxylic groups).  Chroming is carried out by using less than one atom of chromium per dyestuff molecule and/or by working in a weakly acid or alkaline medium.  The chroming agents are preferably derivatives of aliphatic or aromatic hydroxycarboxylic acids, e.g. lactic, glycollic, citric, tartaric, salicylic and the C-methylsalicylic acids.  Bases, organic solvents or salts of organic acids may be added.  Dyestuffs of type (3) above may also be obtained by reacting a 1 : 1-chromium complex of an appropriate dyestuff with a further molecule of the same of different dyestuff free from chromium.  The sulphonamide group may be in the residue R of the 1 : 1-complex or the other dyestuff or both.  The products are suitable for dyeing and printing nitrogenous fibres, e.g. of wool, silk, leather, superpolyamides and superpolyurethanes, from a neutral or weakly acid bath.  Chroming may be effected in the dyebath instead of in substance, e.g. by the metachrome process.  In the examples: (1) 2 - aminophenol - 4 - sulphonamide or its 6-nitro derivative is diazotized and coupled with 1-acetylamino or 1-n-butyrylamino-7-naphthol; (2) diazotized 2-aminophenol-5-sulphonamide is coupled with 1-acetylamino-7-naphthol; (3) the dyestuff 2-aminophenol-4-sulphonamide --> 1 - acetylamino - 7 - naphthol is chromed with potassium-sodium chromisalicylate; (4) a mixture of the dyestuffs 2-aminophenol-4-sulphonamide --> 1-acetylamino-7-naphthol and 4-chloro - 2 - aminophenol --> 1 - acetylamino - 7-naphthol is chromed with sodium chromisalicylate; (5) as in (4) using in addition 2-aminophenol-4-carboxylic acid --> 1-acetylamino-7-naphthol and optionally replacing 4-chloro-2-aminophenol by 4-nitro-2-aminophenol; (6) wool is dyed with the product of (3). A list is given of other suitable dyestuffs and components therefor.  In general, the diazo component may contain one or more halogen, alkyl, alkoxy, nitro, acyl, sulphone or acylamino substituents; the acylamino-naphthol is free from nuclear substituents, but the acyl group may be substituted (except for sulphonic acid and carboxylic groups).  Preferably the acyl group is of the formula -CO-CnH2n+1 (n= 1 to 5) or is a p formyl or urethane group.  Specification 637,404 is referred to.