Pyrazoline-3, 5-dione-containing compositions for dyeing keratin fibres; their use in dyeing as couplers; dyeing process

Composition for dyeing keratin fibres, and in particular human keratin fibres such as :he hair, characterized in that it comprises, in a medium which is suitable for dyeing:

• as coupler, at least one pyrazoline-3,5-dione compound of formula (I) below, or one of addition salts thereof with an acid:
• 9
• in which:
• R2 represents:
• a hydrogen atom;
• a halogen atom such as bromine, chlorine or florine;
• an acetylamido group;
• an alkoxy radical;
• an acyloxy radical;
• an aryloxy radical;
• an arylthio radical, an alkylthio radical;
• a heteroarylthio radical;
• a heteroaryloxy radical;
• a thiocyano radical;
• an N,N-diethylthiocarbonylthio radical;
• a dodecyloxythlocarbonylthio radical;
• a benzenesulphonamido radical;
• an N-ethyltoluenesulphonamido radical;
• a pentafluorobutanamido radical;
• a 2,3,4,5,6-pentafluorobenzamido radical;
• a p-cyanophenylureido radical, an N,N-diethylsulphamoylamino radical;
• a pyrazolyl radical;
• an imidazolyl radical;
• a triazolyl radical;
• a tetrazolyl radical;
• a benzimidazolyl radical;
• a 1-benzyl-5-ethoxy-3-hydantoinyl radical;
• a 1-benzyl-3-hydantoinyl radical;
• 5,5-dimethyl-2,4-dioxo-3-oxazolidinyl;
• a 2-oxy-1,2-dihydro-1-pyridyl radical;
• an alkylamido;
• an arylamido;
• a radical NRIIIRIV with RIII and RIV, which may be identical or different, representing a C1-C4 alkyl, a hydroxyalkyl;
• a carboxyl;
• or an alkoxycarboxylic radical;
• R1 and R3 represent a hydrogen atom;
• a linear or branched C1-C5 alkyl radical;
• a C2-C4 mono- or polyhydroxyalkyl radical;
• a C2-C4 aminoalkyl radical;
• a phenyl radical;
• a phenyl radical substituted with a halogen atom or a C1-C4 alkyl, C1-C4 alkoxy, nitro, trifluoromethyl, amino or C1-C4 alkylamino radical;
• a.benzyl radical;
• a benzyl radical substituted with a halogen atom or with a C1-C4 alkyl, C1-C4 alkoxy, methylenedioxy or amino radical;
• or a radical
• 10
• in which m and n are integers, which may be identical or different, between 1 and 3 inclusive, X represents an oxygen atom or an NH group, Y represents a hydrogen atom or a methyl radical, and Z represents a methyl radical, a group OR or NRR′ in which R and R′, which may be identical or different, denote a hydrogen atom, a methyl radical or an ethyl radical;
• an amino radical;
• a C1-C4 alkylamino;
• a carboxyl radical;
• an alkoxycarbonyl radical;
• an aryloxycarbonyl radical;
• a 5- or 6-membered heterocycle with at least one nitrogen, sulphur or oxygen atom;
• an acyl radical;
• a sulphonyl group;
• a phosphonyl group;
• it being understood that when R2 and R3 simultaneously represent a hydrogen atom, then R1 is other than a hydrogen atom, a C1-C5 alkyl radical or a phenyl radical;
• at least one oxidation base.