SYMMETRICAL DIAZO COMPOUNDS WITH 3-PYRIDINIUM GROUPS AND CATIONIC LINKER ARM, COMPOSITIONS COMPRISING SAME, DYEING METHOD AND DEVICE

摘要

The invention concerns symmetrical diazo cationic compounds of formula (I), their resonance forms, as well as their acid-addition salts and their solvates, wherein: W₁ identical or different represent an oxygen atom, a halogen atom, a -NR₅R₆, OR₇, -NR₄-Ph-NR₅R₆, -NR₄-Ph-OR₇, -O-Ph-OR₇, -O-Ph-NR₅R₆ group; or a particular -NR₅R₆ group; L is a linker arm bearing at least one cationic charge. The invention also concerns dyeing compositions comprising in a medium appropriate for dyeing keratinous fibers, such compounds as direct dyeing agent, as well as a method for dyeing keratinous fibers using said composition and a multiple-compartment device.