Dyeing composition for dyeing keratinous fibers comprising a cationic azo-dye

A composition for dyeing keratinous fibers, and in particular human keratinous fibers such as the hair, comprising at least one cationic azo dye of the following formula (I):

• 16
• in which
• W1 represents a 5-membered cationic aromatic heterocycle of the following formula (II)
• 17
• W2 represents a divalent aromatic carbonaceous or pyridine group of the following formulae (III) and (IV):
• 18
• in which formulae
• Z1 represents an oxygen or sulfur atom or a radical NR4,
• Z2 represents a nitrogen atom or a radical CR3,
• R1 and R4 represent, independently of one another, a C1-C8 alkyl radical optionally substituted by one or more radicals chosen from a hydroxyl, a C1-C2 alkoxy, a C2-C4 (poly)hydroxyalkoxy radical, an amino, a C1-C2 (di)alkylamino, a carboxyl, a sulfonic;
• an optionally substituted phenyl radical,
• R2 and R3 represent, independently of one another, a hydrogen atom;
• a C1-C4 alkyl radical, optionally substituted by one or more radicals chosen from a hydroxyl, a C1-C2 alkoxy, a C2-C4 (poly)hydroxyalkoxy, an amino, a C1-C2 (di)alkylamino;
• a carboxyl or a sulfonic;
• an optionally substituted phenyl radical;
• a carboxyl radical;
• a sulfonylamino radical;
• R5, R6, R7, R8and W4 represent, independently of one another, a hydrogen atom;
• a chlorine atom;
• a bromine atom;
• a linear or branched C1-C6 hydrocarbonaceous chain which can form one or more 3- to 6-membered carbonaceous rings, and which can be saturated or unsaturated, of which one or more carbon atoms of the hydrocarbonaceous chain can be replaced by an oxygen, nitrogen or sulfur atom or by an SO2 group, and the carbon atoms of which can be, independently of one another, substituted by one or more halogen atoms;
• R5, R6, R7, R8 and W4 not comprising a peroxide bond or diazo or nitroso radicals, and W4 being a nonaromatic substituent,
• W3 represents a heteroaromatic ring chosen from the thienyl, pyrazolyl, pyrrolyl, imidazolyl, furyl, triazolyl, thiadiazolyl, isoxazolyl, isothiazolyl, thiazolyl, oxazolyl, pyridyl, pyrimidinyl, triazinyl, pyridazinyl or pyrazinyl rings, it being possible for each of these heteroaromatic rings to be substituted by at least one C1-C6 alkyl radical, optionally substituted by one or more hydroxyl, C1-C4 alkoxy, (poly)hydroxyalkoxy, amino, C1-C4 (di)alkylamino, C2-C4 (poly)hydroxyalkylamino, carboxyl, sulfonyl, alkoxycarbonyl or C1-C4 thioether;
• a phenyl radical optionally substituted by one or more radicals chosen from C1-C2 alkoxy, amino, C1-C2 (di)alkylamino, carboxyl, sulfonyl, C1-C4 alkyl, halogen or C1-C2 thioether radicals, a halogen such as a chlorine, fluorine or bromine atom;
• an amino radical;
• a C1-C4 alkylamino radical, a C2-C4 (poly)hydroxyalkylamino radical, a C1-C4 (di)alkylamino radical;
• a C1-C2 alkoxy radical;
• a carboxyl radical;
• a sulfonylamino radical,
• X is an organic or inorganic anion.