Patent GB-781484-A (GB)
Title: New disazo-dyestuffs and process for making them
IPC: C09B35/26
Filed: 1954-10-11
Abstract: The invention comprises dyestuffs of formula: <FORM:0781484/IV (b)/1> where X1 and X2 are phenylamino groups at least one of the phenyl residues of which contain a group imparting solubility in water. They may be made by treating a monoazo dyestuff of formula: <FORM:0781484/IV (b)/2> X being a phenylamino group containing in the phenyl residue a group imparting solubility in water with phosgene advantageously in a weak aqueous alkaline medium.  The monoazo dyestuff may be made by coupling a diazotized 1-amino - 4 - nitro - o acetylamino - benzene - 2-carboxylic and in an alkaline, preferably weakly alkaline, medium with the appropriate 2-phenylamino - 5 - oxynaphthalene - 7 - sulphonic acid and converting the 4-substituent into an amino group.  Two different naphthol sulphuric acids may be linked by means of phosgene to provide asymmetrical disazo dyestuffs although symmetrical dyestuffs are preferred.  The disazo dyestuffs may also be made by coupling tetrazotized 4,41 - diaminodiphenyl - urea - 3,31 - dicarboxylic acid in an alkaline medium with the appropriate naphthol sulphonic acid or acids.  Groups specified as imparting solubility in water are sulphonamide, carbomethoxy, carboxylic acid and sulphonic acid groups.  The dyestuffs dye many materials especially cellulosic materials, e.g. cotton, linen and artificial silk or regenerated cellulose.  The dyeings may be treated with an agent yielding metal, especially copper, on the fibre, in the dyebath or partially on the fibre and partially in the dyebath as in Specification 455,274, [Group IV].  The coppered dyeings yield violet shades.  In examples: (1) 4 - nitro - 1 - aminobenzene - 2 - carboxylic acid is diazotized, coupled with 2-phenylamino-5-naphthol - 7 - sulphonic acid - 31 - sulphonic acid amide, the nitro group in the monoazo dyestuff thus obtained is reduced to an amino group with sodium hydrosulphide and the product reacted with urea to give a disazo dyestuff also obtainable by indirectly tetrazotizing 4,41-diamino - diphenyl - urea - 3,31 - dicarboxylic acid and coupling with the naphthol 7-sulphonic acid; (2) 1-amino-4-acetylaminobenzene-2-carboxylic acid is diazotized, coupled with 2-(41-carboxymethoxyphenylamino) - 5 - naphthol - 7 - sulphonic acid, the acetylamino group in the monoazo dyestuff thus prepared is hydrolysed with caustic soda and the product treated with urea to yield the desired disazo dyestuff; (3) 4,41 - diaminodiphenylurea - 3,31 - dicarboxylic acid is tetrazotized and coupled with a mixture of 2 - phenylamino - and 2 - (41 - carboxymethoxy - phenylamino) - 5 - naphthol - 7 - sulphonic acid to yield an asymmetrical dyestuff; (4) diazotized 1 - amino - 4 - acetylaminobenzene - 2 - carboxylic acid is coupled with 2-(41 - aminophenylamino) or (41 - methyl phenylamino) - 5 - naphthol - 7,31 - disulphonic acid, or 2-phenylamino-5-naphthol-7-sulphuric acid-31-carboxylic acid, the acetylamino group in the monoazodye-stuff thus obtained is hydrolysed with caustic soda and the product treated with phosgene to yield a disazo dyestuff; (5) 4-nitro-1-aminobenzene-2-carboxylic acid is diazotized, coupled with 2 - (41 - chlorophenylamino)-5-naphthol-7,31-disulphonic acid and the nitro group reduced and the urea formed as in (1) and in (6) 4,41-diaminodiphenylurea-3,31-dicarboxylic acid is tetrazotized and coupled with 2 - (41 - chlorophenylamino) - 5 - naphthol - 7,31-disulphonic acid.ALSO:2 - Phenylamino - 5 - naphthol - 7 - sulphonic acids containing a sulphonamide group in the phenyl nucleus used as coupling components in the preparation of azo dyestuffs, cf. Group Group IV(c), are made by treating 2-amino-5-oxy- or 2,5-dioxy-naphthalene-7-sulphonic acid with an aminobenzene sulphonic acid amide in the presence of a sulphite.  In Example (1) the above sulphonic acids are treated with aniline-3-sulphonic acid amide in the presence of an alkaline solution of sodium bisulphite to yield 2-phenylamino-5-naphthol-7-sulphonic acid-31-sulphonic acid amide.