Azo dyes

A compound of formula (1)

• wherein
• R1 represents hydrogen;
• substituted or unsubstituted C1-5-alkyl;
• substituted or unsubstituted C1-5-alkoxyl;
• substituted or unsubstituted aryl;
• substituted or unsubstituted phenyl;
• p-C1-5-alkoxyphenyl;
• di(C1-5-alkyl)amino groups;
• amino, sulfonic, carboxyl, hydroxyl, halogen, or nitro groups;
• wherein R1 is attached to the aromatic ring at any position and comprises sulfonic;
• k is an integer from 1 to 4,
• r is an integer of 0 or 1;
• A, C represent, independently of each other,
• or tautomeric forms
• wherein D represents C with the proviso that D is not equal to
• B represents
• wherein
• R2, R3, R4, R5, independently of each other, represent hydrogen;
• substituted or unsubstituted C1-5-alkyl;
• substituted or unsubstituted C1-5-alkoxyl;
• substituted or unsubstituted aryl;
• substituted or unsubstituted phenyl;
• p-C1-5-alkoxyphenyl;
• di(C1-5-alkyl)amino groups;
• amino, sulfonic, carboxyl, hydroxyl, halogen, or nitro groups;
• wherein R2, R3, R4, R5 are attached to the aromatic ring at any position;
• and wherein
• R8, R10, and R11, independently of each other, represent hydrogen, substituted or unsubstituted C1-4-alkyl, substituted or unsubstituted C1-4-alkoxy, substituted or unsubstituted aryl, substituted or unsubstituted phenyl, sulfonic, carboxyl, amino, nitro, hydroxyl, or halogen groups, and
• X represents O, S, NH, SO2, CH═CH, NHCO, NH—CO—NH, N═N, N═N(O);
• m, s independently of each other, are an integer from 1 to 4;
• and
• n, p independently of each other, are an integer from 1 to 3.