6-azo-5,5′-dihydroxy-7,7′-disulfo-2-2′ dinaphthylamine derivatives

6-azo-5,5′-dihydroxy-7,7′-disulfo-2,2′-dinaphthylamine derivatives of formula

• in which
• a is 1-4
• n is 0 or 1,
• R3 represents hydrogen, C1-4-alkyl, C3-4-cycloalkyl, aralkyl, phenyl, C1-4-alkoxy, sulfo, hydroxy, nitro, halogen, C1-4-alkylcarbonyl, carboxy, carbamoyl, C1-4-alkoxy-carbonyl, C1-4-alkylaminocarbonyl, cyano, amino, ureido or NHCOC1-4-alkyl, whereby C1-4-alkyl and C1-4-alkoxy may be substituted with hydroxy or C1-4-alkoxy, and phenyl may be substituted with C1-4-alkyl, C1-4-alkoxy, sulfo, hydroxy, nitro, halogen or carboxy, and
• A1 if n is 1 is selected from the group consisting of
• in which
• m, p and q are identical or different, and are 0, 1 or 2,
• R5 and R6 are identical or different and represent hydrogen, C1-4-alkyl, C3-6-cycloalkyl, aralkyl, phenyl, C1-4-alkoxy, sulfo, hydroxy, nitro, halogen, C1-4-alkylcarbonyl, carboxy, carbamoyl, C1-4-alkoxycarbonyl, C1-4-alkylaminocarbonyl, cyano, amino, ureido or NHCOC1-4-alkyl, whereby C1-4-alkyl and C1-4-alkoxy may be substituted with hydroxy or C1-4-alkoxy, and phenyl may be substituted with C1-4-alkyl, C1-4-alkoxy, sulfo, hydroxy, nitro, halogen or carboxy, and
• A1 if n is 0 is
• R2 represents H or
• in which
• w is 0 or 1,
• R7 and R8 are identical or different and represent hydrogen, C1-4-alkyl, C3-6-cycloalkyl, aralkyl, phenyl, C1-4-alkoxy, sulfo, hydroxy, nitro, halogen, C1-4-alkylcarbonyl, carboxy, carbamoyl, C1-4-alkoxycarbonyl, C1-4-alkylaminocarbonyl, cyano, amino, ureido or NHCOC1-4-alkyl, whereby C1-4-alkyl and C1-4-alkoxy may be substituted with hydroxy or C1-4-alkoxy, and phenyl may be substituted with C1-4-alkyl, C1-4-alkoxy, sulfo, hydroxy, nitro, halogen or carboxy, and
• A2 represents either A1, whereby A1 has the meaning as indicated for the 6-azo-5,5′-di-hydroxy-7,7′-disulfo-2,2′-dinaphthylamine derivatives of the claimed formula (1), or A2 represents
• in which
• R9 and R10 are identical or different and represent hydrogen, C1-4-alkyl, C1-4-alkoxy, sulfo, hydroxy, nitro or carboxy,
• E represents sulfur or NH.