Patent ID: 7374581

Claim:
A process for dyeing human keratin fibers, comprising applying to said fibers a composition comprising, in a suitable medium, at least one direct cationic hydrazone dye of formula (I), or a tautomeric form thereof: wherein R 1 and R 7 are, independently of each other, chosen from C 1 -C 6 alkyl, C 1 -C 6 hydroxyalkyl, benzyl, p-chlorobenzyl and phenyl radicals, R 4 is chosen from a hydrogen atom and C 1 -C 6 alkyl radicals, R 2 , R 3 , R 5 , R 6 and R 8 are, independently of each other, chosen from hydrogen atoms, C 1 -C 6 alkyl radicals, halogen atoms, nitro radicals, C 1 -C 6 alkoxy radicals, amino radicals, C 1 -C 6 alkylamino radicals, C 1 -C 6 dialkylamino radicals, sulfamoyl radicals, C 1 -C 6 dialkylsulfamoyl radicals, C 1 -C 6 dihydroxyalkylamino radicals and C 1 -C 6 dihydroxyalkylamino radicals, R 1 may form, with R 2 or R 3 and the atoms to which they are attached, a saturated or unsaturated, 5-, 6- or 7-membered ring optionally substituted with at least one C 1 -C 6 alkyl radical, or optionally fused with a benzene nucleus, R 1 and R 4 may form, together with the atoms to which they are attached, a 5-, 6- or 7-membered unsaturated ring, R 5 and R 6 may form, together with the atoms to which they are attached, a saturated or unsaturated 5-, 6- or 7-membered ring, wherein the bonding between the hydrazone group and the quinoline group takes place on any of the atoms of the quinoline heterocycle, and X − is an anion that ensures the neutrality of the molecule.