Patent ID: 7785375

Claim:
Method of dyeing keratin-containing fibers comprising treating the fiber with at least one compound of formula (1) wherein R 1 , R 2 , R 3 , R 4 independently from each other are hydrogen; hydroxy; —S—H; —S—C 1 -C 12 alkyl; halogen; C 1 -C 12 alkyl or C 1 -C 12 alkoxy, which may be substituted by one or more C 1 -C 5 alkyl, C 1 -C 5 -alkoxy, hydroxy, —(CO)—H or —(CO)—C 1 -C 5 alkyl; —NR 5 R 6 ; —NO 2 ; —(CO)H or (CO)—C 1 -C 5 alkyl; or C 6 -C 12 aryl, C 6 -C 12 aryl-C 1 -C 4 alkyl or C 6 -C 12 aryl-C 1 -C 4 alkoxy, wherein the aryl moiety may be substituted by one or more C 1 -C 5 alkyl, C 1 -C 5 alkoxy, —(CO)—H or —(CO)—C 1 -C 5 alkyl; R 5 and R 6 independently from each other are hydrogen; hydroxy; C 1 -C 12 alkyl; hydroxy-C 1 -C 12 alkyl; —(CO)—H; —(CO)—C 1 -C 5 alkyl; or phenyl or phenyl-C 1 -C 5 alkyl, wherein the phenyl moiety may be substituted by one or more C 1 -C 5 alkyl, C 1 -C 5 alkoxy, halogen, —NH 2 , mono-C 1 -C 5 alkylamino, di-C 1 -C 5 alkylamino, —NO 2 , carboxy or hydroxy; and An − is an anion.