Patent GB-430167-A (GB)
Title: Improvements relating to the manufacture of azo dyestuffs
IPC: C09B41/00
Filed: 1933-12-12
Abstract: Azo dyes are made in substance, on a substratum or on the fibre by treating mixtures of salts of aromatic nitramines and coupling components with nitrous acid in presence of water.  The coupling components should be resistant to nitrous acid under the reaction conditions.  Alternatively, mixtures containing aromatic nitraminates, the coupling components and a nitrite are treated with an acid.  The nitraminates are converted into the corresponding diazo compounds by the nitrous acid.  In examples: (1) a mixture of p-nitrophenyl nitraminate of sodium, N-dimethylsulphanilate of sodium and sodium nitrite is treated with acetic acid to form the azo dye p-nitrobenzene-azo-dimethylaminobenzene sulphonic acid; (2) a mixture of 2 : 5-dichlorotolyl-4-nitraminate, 6 - hydroxy - 2 - naphthalene sulphonate and sodium nitrite is treated with acetic or sulphuric acid; (3) a solution of 1-methyl-3-nitro-6-nitraminate and the sodium salt of 2 : 3-oxynaphthoic acid anilide is treated with nitrous vapours; or (4) cotton impregnated with the solution is exposed to moist nitrous vapours; (5) goods are printed with a paste containing the sodium salt of 2 : 5-dichlorophenylnitramine, sodium nitrite and diacetoacetyltolidine, dried and passed through a formic acid/sodium sulphate solution.  The Specification as open to inspection under Sect. 91 refers also to the use of free nitramines and to compositions containing metal salts, (list given), solvents (e.g. ethanol, glycerine, glycol ether or pyridine), diluents, thickeners and stabilizers, e.g. aldehydes or glucose.  The nitramines may contain substituents, e.g. nitro, halogen, thio, arylazo, aralkyl, aryl, arylcarbonyl, sulphonaryl, alkyl, alkoxy, phenoxy and substituted amino groups and may be derived from nitranilines, chloranilines, chloranisidines, m-xylidine, o-phenetidine, o-anisidine, nitrotoluidines, nitroanisidines, nitrochloranilines, nitrochlorotoluidines, chlortoluidines, naphthylamines, aminohydroquinone ethers, monoacidyl-p-phenylene diamines, aminoketones, e.g. aminoacetophenones, aminobenzophenones, aminosulphones, e.g. aminomethylsulphones, aminodiphenylsulphones, monoaminodiphenyls, aminoalkoxydiphenylamines, aminodiphenylethers, diaminodiphenyls, aminocarbazoles and aminoanthraquinones.  Azo coupling components specified in general are b -ketonic acid derivatives, naphthols and their derivatives, hydroxycarboxylic acids and their arylides, hydroxynaphthindoles, 4-oxynaphthylphenylketone, 1 : 3-dioxyquinoline and sulphazones.  The free nitramines and components may be mixed with an alkali and the nitrite.  The treatment with the acid may be followed by a second treatment with an alkali.  In examples, textiles are printed with pastes containing sodium nitrite and the following components and the colour developed as indicated: (1) o-nitrophenyl nitraminate and the anilide of 2 : 3-oxynaphthoic acid developed first with sulphuric acid and then with sodium acetate; (2) 1-methyl-3-nitro-6-nitramine, p-anisidide of 2 : 3-oxynaphthoic acid and caustic soda developed with acetic acid; (3) 1-methoxy-4-nitro-6-nitraminate and the m-nitranilide or 4-chlor-2-methyl-1-anilide of 2 : 3-oxynaphthoic acid developed first with oxalic acid and then with sodium carbonate; (4) 1-methyl- or 1-chlor-3-nitro-4-phenylnitraminate and 2 - hydroxy - 3 - naphthoylaniline developed with sulphuric acid and then with sodium carbonate; (5) 1-methoxy-3-nitro-6-phenylnitraminate and hydroxynaphthocarbazole carboxylic acid anilide or 2-hydroxy-3-carbazolecarboxylic acid arylide developed with a bath of formic acid, salt and sodium bisulphate; (6) 1-methoxy-3-nitro-6-phenylnitraminate and 4-hydroxynaphthylphenylketone or the components of U.S.A. Specification 1,453,660 developed with acetic acid.  This subject-matter does not appear in the Specification as accepted.