Patent ID: 6893471

Claim:
A composition for dyeing keratin fibers, comprising at least one dicationic diazo dye of formula (I) below: W 1 —N═N—W 2 —N═N—W 3 wherein W 1 and W 3 , which may be identical or different, are chosen from heteroaromatic groups chosen from formulae (II) and (III) below: W 2 is chosen from carbon-based, pyridine-based and pyridazine-based aromatic groups of formula (IV) wherein, in formulae (II), (III), and (IV): X 1 is chosen from nitrogen and CR 5 , X 2 is chosen from nitrogen and CR 6 , Z 1 is chosen from oxygen, sulfur and NR 8 , Z 2 is chosen from nitrogen and CR 9 , Z 3 is chosen from nitrogen and CR 12 , Z 4 is chosen from nitrogen and CR 13 , bond a of the 5-membered cationic ring of formula (II) may be linked to the azo group of formula (I), bond b of the 6-membered cationic ring of formula (III) may be linked to the azo group of formula (I), R 3 , R 4 , R 5 , R 6 , R 7 , R 9 , R 10 , R 11 , R 12 , and R 13 , which may be identical or different, are chosen from hydrogen and frorp linear and branched, saturated and unsaturated, C 1 -C 16 hydrocarbon-based chains, wherein the chains can form at least one carbon-based ring comprising from 3 to 6 carbons, wherein at least one carbon atom of the carbon-based chain may be replaced with an entity chosen from oxygen, nitrogen and sulfur atoms and SO 2 groups, and wherein the at least one carbon atom may be substituted with at least one halogen atom; wherein none of R 3 , R 4 , R 5 , R 6 , R 7 , R 9 , R 10 , R 11 , R 12 , and R 13 , comprises a peroxide bond, a diazo radical or a nitroso radical, R 7 with R 9 , R 10 with R 11 and R 12 with R 13 may form carbon-based aromatic rings, and X is chosen from organic and mineral anions.