GB451665A - Process for the manufacture of azodyestuffs - Google Patents

Abstract

Azo dyes are prepared by condensing an aminoazo dye of the type A--N=N--B--NH2 wherein A and B are aromatic radicles of which A may contain a further azo linkage and wherein the amino group of the radicle B is in o-position to the azo linkage, with a nitroaroyl chloride and reducing the nitro group to the amino group. These products or similar products obtained by repeating the condensation several times may be converted to other azo dyes by diazotization and coupling, which may be followed by further condensation with a nitroaroyl chloride, reduction, diazotization and coupling; these further diazotizations and couplings may be performed in substance or on the fibre. In all cases the products give dyeings which are dischargeable in alkaline or neutral solution. In examples: (1) o-aminoazobenzene-3<1>-sulphonic acid is condensed with p-nitrobenzoyl chloride and reduced by means of sodium sulphide and again aminobenzoylated; this product dyes cotton yellow shades which on development with 1-phenyl-3-methyl-5-pyrazolone yield a yellow shade and with b -naphthol an orange shade; (2) o-aminodisazobenzene-4<1>-sulphonic acid is condensed with p-nitrobenzoyl chloride and reduced; it dyes cotton reddish yellow shades which on development with 1-phenyl-3-methyl-5-pyrazolone yield a yellow shade and with b -naphthol an orange shade; (3) the p-aminobenzoyl-o-aminoazobenzene-3<1>-sulphonic acid of (1) is diazotized and coupled with 2-(p-aminobenzoylamino)-5-naphthol-7-sulphonic acid to give a product dyeing orange-red shades, changed by development with b -naphthol to a reddish-orange; using instead 2-(m-aminobenzoylamino)-5-naphthol-7-sulphonic acid a similar dye is obtained but which yields on development on the fibre with b -naphthol more yellowish-orange shades; (4) p-aminobenzoyl-o-aminoazobenzene-3<1>-sulphonic acid is diazotized and coupled with 1 - (3<1> - aminophenyl) - 3 - methyl - 5 - pyrazolone; the product dyes the fibre greenish-yellow shades which are unchanged on development with 1-phenyl-3-methyl-5-pyrazolone, while on development with 1-(p-aminophenyl)-3-methyl-5-pyrazolone a reddish-yellow shade is obtained; the m-aminophenylmethylpyrazolone may be replaced by 1-phenyl-3-methyl-5-pyrazolone to give a dye yielding greenish-yellow shades; (5) the azo dye from 2-nitronaphthalene-4.8-disulphonic acid and o-phenylenediamine prepared according to Specification 451,673 is converted to the p-aminobenzoyl derivative as described in (1), diazotized and coupled with 2-(m-aminobenzoyl-m-aminobenzoyl)amino-5-naphthol-7-sulphonic acid; the product dyes yellow shades and may be developed on the fibre with b -naphthol; acetyl-J-acid may be used in place of the aroylated-J-acid. Specifications 341,898 and 351,322 also are referred to. The Specification as open to inspection under Sect. 91 comprises the conversion of the aroylated o-aminoazo dyes into other derivatives in a manner known for aminoazo dyes and instances the conversion into ureas or thioureas, but this subject-matter does not appear in the Specification as accepted.