Patent GB-583849-A (GB)
Title: Manufacture of azo-dyestuffs
IPC: C09B43/14
Filed: 1943-06-17
Abstract: Asymmetrical disazo dyes are made (a) by uniting 1 mol. of an azo dye of the general formula R-x-R1-y-R2-NH2 with one of the general formula R4-N=N-R3-NH2 by treatment with phosgene; (b) by diazotising 1 mol. of an azo dye of the general formula R-x-R1-y-R2-NH.CO.NH-R3-NH2 or H2N-R1-y-R2-NH.CO.NH-R3-N=N -R4 and coupling with an o-oxycarboxylic acid of the benzene series; or (c) by tetrazotising a urea of the general formula H2N-R1-y-R2-NH.CO.NH-R3-NH2 and coupling with 2 mols. of the same or different o-oxycarboxylic acids of the benzene series.  In the foregoing formul , R and R4 represent aromatic nuclei of the benzene series containing a hydroxy and a carboxyl group in o-position to one another, x and y represent an -N=H- group and a -CO.NH- or -NHCO- group respectively of an -NHCO- group and an -N=N- group respectively (but in those formul  in which x does not occur, y must be an -NH.CO- or -CO.NH- group), and R1, R2 and R3 represent aromatic nuclei of the benzene series in which any nitrogen atoms bound directly to the same nucleus are in p-position to one another, and any -CO- groups and nitrogen atoms bound directly to the same nucleus are in p- or m-position to one another; and the components are so chosen that the final dyestuff contains only one sulphonic acid group, the benzene nucleus directly attached to the -CO- group contains no sulphonic acid group, and R is also free from sulphonic acid groups when the -CO- group is attached directly to R2.  The products are direct cotton dyes, the dyeings with which may be after-treated with an agent yielding copper.  They may also be applied to mixed fabrics, e.g. of wool and viscose staple fibre, advantageously in a neutral bath in the presence of sodium or potassium chromate.  In examples: (1) phosgene is passed into a solution, alkaline with sodium carbonate, containing 4-amino-41-oxy-1 : 11-azobenzene-31-carboxylic acid and the product obtained by diazotizing 1-amino-4-acetylaminobenzene-2-sulphonic acid, coupling with salicylic acid, saponifying, m-nitrobenzoylating and reducing; (2) phosgene is similarly reacted with 41-(411-amino)-benzoylamino-1 : 11-azobenzene-4-oxy-3-carboxylic acid and 41-amino-1 : 11-azobenzene-4-oxy-3-carboxy-21-sulphonic acid; (3) the last compound is replaced by 41-amino-1 : 11-azobenzene-21-methyl-51-methoxy-4-oxy-3 -carboxy-5-sulphonic acid; (4) phosgene is similarly reacted with 4-amino-41-oxy-1 : 11 azobenzene-31-carboxylic and the product obtained by saponifying the dyestuff 1-(41-aminobenzoyl)-amino-4-acetylaminobenzene-2-sul-phonic acid --> salicylic acid; and (5) with 41-amino - 1 : 11 - azobenzene - 21 - methyl - 51 - methoxy-4-oxy-3-carboxy-5-sulphonic acid and the dyestuff 4 - (41 - aminobenzoyl) - amino - 1 - oxybenzene-2-carboxylic acid --> m-toluidine; (6) phosgene is reacted with this last dyestuff and 1 : 4-diaminobenzene-2-sulphonic acid, and the product is diazotized and coupled with salicylic acid; (7) phosgene is reacted with 4-aminophenyloxamic acid and 1 : 4-diaminobenzene-2-sulphonic acid, and the product is p-nitrobenzoylated, reduced, saponified, tetrazotized and coupled with 2 mols. of salicylic acid; (8) cotton is dyed with the product of (3) from a bath containing sodium carbonate and, in the later stages, sodium sulphate, and is after-treated in the same bath with a solution of copper sulphate and tartaric acid neutralized with caustic soda, yielding a greenish yellow shade. A number of additional starting materials of the types R-x-R1-y-R2-NH2, R4-N=N-R3-NH2 and H2N-R1-y-R2-NH.CO.NH-R3-NH2 are specified. Specification 555,791 is referred to.  The Specification as open to inspection under Sect. 91 comprises also the use of 4-amino-41-(411-amino-311-sulpho) -benzoylaminodiphenylurea as a starting material in process (c) above.  This subject-matter does not appear in the Specification as accepted.