Patent GB-699976-A (GB)
Title: Chromiferous and cobaltiferous azo dyestuffs and process of making same
Filed: 1951-04-20
Abstract: 6 - Nitro - 2 - aminophenol - 4 - sulphonamide is made by nitrating 2-acetylaminophenol-4-sulphonamide and hydrolysing the product.  4 - Nitro - 2 - aminophenol - 6 - sulphonamide is prepared as follows: sodium 2 : 4-dinitro-chloro-benzene-6-sulphonate is converted into the sulphonyl chloride by treatment with chloro-sulphonic acid and then into the sulphonamide with ammonia.  The product is refluxed with an aqueous suspension of calcium hydroxide and the resulting 2 : 4-dinitrophenol 6-sulphonamide partially reduced with sodium sulphide.ALSO:The invention comprises chromium and cobalt compounds which contain one atom of metal in complex union with two mols. of different o : o1-dioxymonoazo dyestuffs free from sulphonic acid and carboxyl groups; at least one contains a sulphonamide group and at least one is a 2 : 21-dioxy-azobenzene with one or two nitro groups in one ring.  Such compounds are made by (1) metallizing a mixture of the two metal-free dyestuffs or a product resulting from the reaction of two mols. of a diazo compound on a mixture of two different coupling components; or (2) metallizing one of the dyestuffs to give a 1 : 1 complex and then reacting it with the other metal-free dyestuff.  Process (1) is preferably carried out in alkaline solution with the complex metal derivative of an aromatic or aliphatic hydroxycarboxylic acid, e.g. salicylic acid.  The metallizing step of (2) is effected in acid solution using a cobalt or chromic salt; the monoalkyl ether of the dyestuff may be used, dealkylation taking place during the metallization.  In method (2) the dyestuffs are preferably used in equimolecular proportions and the one containing a sulphonamide group is preferably metallized first.  In either case mixtures may be obtained by using more than two different dyestuffs. The products are suitable for dyeing and printing silk, leather, wool and synthetic fibres of superpolyamides and superpolyurethanes. The metal-free monoazo dyestuffs are made from the appropriate diazo components and coupling components in the usual way.  In one case the coupling components are phenols, preferably with a p-alkyl or p-acylamino substituent.  The coupling component for the other dyestuff may be a phenol, naphthol, hydroxyquinoline, pyrazolone, barbituric acid or b -keto-carboxylic arylide.  In the examples (1) a mixture of the dyestuffs 4-nitro-2-aminophenol --> p-cresol and 4 - nitro 6 - chloro - 2 - aminophenol --> 1 - (m - sulphonamidophenyl) - 3 - methyl - 5 - pyrazolone is heated with sodium potassium chromosalicylate and sulphonated castor oil; (2) a mixture of the dyestuffs 4-nitro-6-acetylamino - 2 - aminophenol --> 4 - tert - amyl - phenol and 2 - aminophenol - 4 - sulphonamide --> 1 - phenyl - 3 - methyl - 5 - pyrazolone is heated with cobalt sulphate and sodium tartrate; (3) using the same components as in (1), the first dyestuff is metallized (with chromium fluoride, formic acid and ethanol) and then heated with the second; (4) the dyestuff 2 - aminophenol - 4 - sulphon - amide --> 1 - (m - sulphonamidophenyl) - 3 - methyl - 5 - pyrazolone is metallized with chromium formate and then reacted with the dyestuff 4 : 6 - dinitro - 2 - aminophenol --> p - cresol; (5) a mixture of the dyestuffs 4-nitro-6-acetylamino - 2 - aminophenol --> 4 - tert - amyl - phenol, 4 : 6 - dinitro - 2 - aminophenol --> 4 - methyl - 2- acetylaminophenol and 4 - nitro - 6 - chloro - 2 - aminophenol --> 1 - (m - sulphonamidophenyl) - 3 - methyl - 5- pyrazolone is heated with sodium potassium chromosalicylate; (6) a mixture of the dyestuffs 2-aminophenol - 4 - sulphonamide --> 1 - acetyl - amino - 7 - naphthol, 4 - nitro - 6 - chloro - 2 - aminophenol --> 1 - (m - sulphonamidophenyl)-3 - methyl - 5 - pyrazolone and 4 - nitro - 6 - acetylamino - 2 - aminophenol --> 4 - tert - amyl - phenol is metallized as in (1); (7) 4 - nitro - 2 - aminophenol - 6 - sulphonamide is diazotized and coupled with 4-tert-amylphenol in the presence of sodium naphthalene-1-sulphonate; the product is mixed with the dyestuff 4 - nitro - 2 - aminophenol --> 1 - phenyl - 3 - methyl - 5 - pyrazolone and metallized as in (5). Specification 693,245 is referred to.