Acid dyes

A compound of the general formula (I)

• wherein
• R1 and R8 are independently selected from the group consisting of:
• unsubstituted unbranched C1-6alkyl, unsubstituted branched C3-6alkyl, substituted unbranched C1-6alkyl, and substituted branched C3-6alkyl,
• R2 and R7 are independently selected from the group consisting of:
• substituted aryl, unsubstituted aryl, substituted —(CH2)n-aryl, and unsubstituted —(CH2)n-aryl wherein n=1, 2, 3 or 4,
• R3 and R6 are independently selected from the group consisting of:
• hydrogen, unsubstituted unbranched C1-6alkyl, unsubstituted branched C3-6alkyl, substituted unbranched C1-6alkyl, substituted branched C3-6alkyl, unsubstituted unbranched C1-6alkoxy, unsubstituted branched C3-6alkoxyl substituted unbranched C1-6alkoxy, substituted branched C3-6alkoxy, halogen, —NHCO—(C1-6alkyl) with an unbranched C1-6alkyl group, which is substituted or unsubstituted, —NHCO—(C3-6alkyl) with a branched C3-6alkyl group, which is substituted or unsubstituted, and —NHCONH2,
• R4 and R5 are independently selected from the group consisting of:
• hydrogen, unsubstituted unbranched C1-6alkyl, unsubstituted branched C3-6alkyl, substituted unbranched C1-6alkyl, substituted branched C3-6alkyl, and halogen,
• and wherein the compound of the general formula (I) contains at least one anionic substituent.