Patent GB-497862-A (GB)
Title: Improvements in or relating to the manufacture of azo dyestuffs
IPC: C09B29/20
Filed: 1937-08-12
Abstract: Insoluble azo dyes are prepared in substance or on the fibre by coupling arylamides of o-hydroxy carboxylic acids or of acylacetic acids with diazotized amines of the general formula <FORM:0497862/IV/1> wherein the benzene nucleus substituted by the amino group as well as the other aryl radicle may be substituted by halogen atoms or alkyl or alkoxy groups.  The dyes can be produced on cotton, viscose or other natural or artificial fibres, with or without the intermediate formation of nitrosamines, diazoamino derivatives, diazosulphonates or Schiff bases, as described in Specification 459,766.  When prepared in substance they can be used for dyeing lacquers, varnishes, and colouring rubber, organic solvents, and plastic masses.  In an example, the phenyl ester of 1-chloro-3-amino-4-benzenesulphonic acid is converted into the diazonium fluoroborate, which is ground with a mixture of sodium naptthalene-2 : 7-sulphonate and aluminium sulphate, and the product dissolved in water to form a bath in which cotton, previously treated with a solution of the b -naphthylamide of 2 : 3-hydroxynaphthoic acid, is developed.  In a table, dyes are specified from the following additional components: diazo components, the phenyl ester of o-sulphanilic acid and the p-cresyl ester of 1-chloro-3-amino-4-benzenesulphonic acid; coupling components, the anilide, m-nitranilide, 5-chloro-2-toluidide, p- and o-anisidide, o-toluidide, a -naphthylamide, p-chlor-o-anisidide, and 2.4 - dimethoxy - 5 - chloroanilide of 2.3-hydroxynaphthoic acid and diacetoacetyl-o-tolidine.  Specifications 6379/12, [Class 2 (iii)], 17279/13, and 210,217, [both in Class 15 (ii)], also are referred to. The aryl esters of o-sulphanilic acid and their derivatives can be obtained by condensing o-nitrobenzene sulphochloride or its substitution products with alkali phenolates or their substitution products in the absence of water and either in the presence of excess of phenol or in a neutral solvent, e.g. benzene, toluene and chlorobenzene, and reducing the product. Examples are given of the preparation of the phenyl esters of o-sulphanilic acid, 1-chloro-3-amino-4-benzene-sulphonic acid and 1-methyl-3-amino-4-benzene-sulphonic acid; the p-cresyl, o-chlorophenyl, 2.5-dichlorophenyl and 2.4.6-trichlorophenyl esters of 1-chloro-3-amino-4-benzene-sulphonic acid; and the o-cresyl ester of o-sulphanilic acid by this method.  In general, the alkali salts of o-, m- and p-cresols, o-, m- and p-chloro-phenols, di- or tri-chlorophenols, and the monoalkyl derivatives of hydroquinone and resorcinol may be used to prepare the esters.  The Specification as open to inspection under Sect. 91 comprises dyes prepared by coupling substantive coupling components in general with diazotized aryl esters of o-sulphanilic acid or their derivatives containing substituents incapable of causing solubility in water.  This subject-matter does not appear in the Specification as accepted.ALSO:Rubber is coloured with insoluble azo dyes prepared by coupling aryl amides of o-hydroxy carboxylic acids or of acylacetic acids with diazotized amines of the general formula <FORM:0497862/V/1> wherein the benzene nucleus substituted by the amine group as well as the other aryl radicle may be substituted by halogen atoms or alkyl or alkoxy groups.  The Specification as open to inspection under Sect. 91 comprises the use of dyes prepared by coupling substantive coupling components in general with diazotized aryl esters of o-sulphanilic acid or their derivatives containing substituents incapable of causing solubility in water.  This subject-matter does not appear in the Specification as accepted.