GB465174A - Process for the manufacture of polyazodyestuffs - Google Patents

Abstract

Polyazo dyes are made by coupling one mol. of a disazo dye of the general formula R3--N = N--R1--N = N--R2 (R1 = residue of a diazo component, R2 and R3=residues of unsulphonated dihydroxy- or aminohydroxy coupling components of the benzene or naphthalene series which couple at least twice), calculated for each molecular proportion of the said coupling components, with one or two mols. of the same or different diazo compounds, either simultaneously or successively in either sequence. When R1 = a residue of the benzene series the process may be modified by coupling an azo compound of the general formula R1--N = N--R2, in which R1 bears a substituent capable of being converted into an amino group, with one or two mols. of the same or different diazo compounds, converting the said substituent of R1 into the amino group, diazotizing, coupling with the component R3 and finally coupling with one or two mols. of the same or different diazo compounds. R1 may be a residue of the benzene, naphthalene, diphenyl, diphenylamine or diphenylurea series which may be substituted, e.g. by nitro or sulphonic acid groups and R2 and R3 may residues of resorcinol m-aminophenol or 2-amino 6- or 7-naphthol. They dye leather in intense brown shades fast to acids and alkalies. The disazo dyes used as starting materials may be made by coupling 1 mol. of a diazo compound containing at least one substituent convertible into an amino group, e.g. nitro or acylamino, with 1 mol. of R2 or R3, converting the said substituent into the amino group, diazotizing and coupling with R3 or R2, or by coupling the tetrazo compound corresponding with R1 and coupling with R2 and R3. The following dyes are described in examples: (1) 4-41-diaminodiphenyl-2 : 21-disulphonic acid \sQ resorcinol (2 mols.) \sx p-sulphanilic acid (2 mols.), (2) the dyestuff of (1) is coupled with diazotized p-sulphanilic acid (2 mols.), (3) p-sulphanilic acid --> resorcinol \sM p-nitroaniline (reduced) <FORM:0465174/IV/1> A table of similar combinations is given in which the following additional components are specified: R1 : benzidine, p-phenylenediamine sulphonic acid, p<1>-aminobenzoyl-p-phenylenediamine, 1 : 3-phenylenediamine-2-chlor-5-sulphonic acid; diazo components; primuline sulphonic acid, 1-naphthylamine-4-sulphonic acid, picramic acid. According to the Provisional Specification R2 and R3 may be the residues of unsulphonated diamines of the benzene and naphthalene series, e.g. m-phenylenediamine.