Particular quinone direct dyes, dye composition comprising at least one such dye, implementation process therefor and use thereof The present invention relates to particular quinone direct dyes and also to the use thereof for dyeing keratin fibres, in particular human keratin fibres such as the hair.

The invention also relates to a composition for dyeing keratin fibres comprising such quinone direct dyes in a suitable dyeing medium, and also to a dyeing process using the said composition.

Specifically, a subj ect of the invention is precursors of these direct dyes, their use for dyeing fibres and a multi-compartment device containing them.

The present invention relates to the field of dyeing keratin fibres and more particularly to the field o f hair dyeing.

It is known practice to dye keratin fibres, and in particular the hair, with dye compositions containing one or more direct dyes, according to a "direct dyeing" process .

The process conventionally used in direct dyeing consists in applying to keratin fibres one or more direct dyes, or colouring mo lecules, which have affinity for the said fibres, leaving them to stand on the fibres, and then rinsing the fibres . The direct dyes used hitherto are generally nitrobenzene dyes, anthraquinone dyes, nitropyridine dyes, dyes of azo, xanthene, acridine or azine type or triarylmethane-based dyes.

These direct dyes may also be applied to keratin fibres in the presence of an oxidizing agent if it is desired to obtain simultaneous lightening of the fibres .

However, the colorations resulting therefrom are temporary or semi-permanent since the nature of the interactions that bind the direct dyes to the keratin fibre and their desorption from the surface and/or the core of the fibre are responsible for their weak dyeing power and their poor fastness with respect to washing, inclement weather or perspiration. These dyes also have the drawback of lacking stability towards light, on account of the poor resistance of the chromophore to photochemical attack, which has a tendency to lead to fading over time of the coloration of keratin fibres.

There is thus a real need for direct dyes that can not only dye keratin fibres satisfactorily, but that are also stable towards light, and are capable of giving colorations that are resistant to the various attacking factors to which the fibres may be subjected, such as bad weather, washing and perspiration.

These aims are achieved with the present invention, one subject of which is especially quinone direct dyes of formula (I) below, organic or mineral acid or base salts thereof, tautomeric forms, optical isomers or geometrical isomers thereof and/or solvates thereof:

in which formula (I):

• n represents an integer equal to 0, 1, 2, 3 or 4;

R represents:

- a linear or branched C1-C4 alkyl radical;

- a linear or branched C1-C4 alkyl radical, substituted with one or more identical or different radicals chosen from hydroxyl and imidazolium radicals, An ^" ; An ^" denoting a cosmetically acceptable anion or mixture of anions;

- a C1-C4 alkoxy radical;

- a halogen atom;

Ri represents:

- a linear or branched C1-C5 alkyl radical;

- a linear or branched C1-C5 alkyl radical, optionally substituted with one or more hydroxyl radicals;

R ₂ represents: - a linear or branched C ₁ -C ₅ alkyl radical;

- a linear or branched C ₁ - C ₅ alkyl radical, optionally substituted with one or more hydroxyl radicals;

• X represents :

- a hydroxyl radical;

- a radical -NR ₃ R ₄ in which R ₃ and R ₄ represent, independently of each other:

^■ a hydrogen atom;

^■ a linear or branched C i -C ₆ alkyl radical;

" a linear or branched C i -C ₆ alkyl radical, substituted with one or more hydroxyl or C ₁ - C4 alkoxy radicals . Another subj ect of the present invention concerns the use of one or more quinone direct dyes of formula (I) as defined previously for the dyeing of keratin fibres, in particular human keratin fibres such as the hair.

The present invention also relates to a composition for dyeing keratin fibres, in particular human keratin fibres such as the hair, comprising, in a suitable dyeing medium, one or more quinone direct dyes o f formula (I) as defined previously.

In particular, the invention also relates to the use of the said dye composition for dyeing keratin fibres, especially human keratin fibres such as the hair.

The invention also relates to a process for dyeing keratin fibres, in particular human keratin fibres such as the hair, in which the said dye composition according to the invention is applied to the said fibres for a time that is sufficient to obtain the desired coloration, after which the resulting fibres are rinsed, optionally washed with shampoo, rinsed again and dried or left to dry.

Similarly, the invention relates more particularly to a process for lightening keratin fibres, in particular human keratin fibres such as the hair, in which (i) the said dye composition, free o f oxidizing agent, and (ii) a cosmetic composition comprising one or more oxidizing agents are applied to the said fibres; compositions (i) and (ii) being applied to the said keratin fibres sequentially or simultaneously for a time that is sufficient to obtain the desired lightening, after which the fibres are rinsed, optionally washed with shampoo and rinsed again, and the resulting fibres are dried or left to dry.

The quinone direct dyes of formula (I) according to the invention can thus give co lorations that are resistant to the various attacking factors to which keratin fibres may be subj ected, such as inclement weather, light, washing and perspiration.

Furthermore, the direct dyes according to the invention can satisfactorily dye keratin fibres, especially producing powerful, chromatic, sparingly selective co lorations and lead to an improved uptake of the co louration.

The direct dyes according to the invention have the advantage of being light-fast and can be used in the presence of an oxidizing agent, which facilitates their use in lightening direct dyeing compositions based on oxidizing agents .

In other words, the direct dyes according to the present invention lead to fast co lorations and are compatible with dye compositions intended for lightening keratin fibres.

Moreover, a subj ect of the invention is co lourless or weakly co loured compounds o f leuco type, which are the reduced form o f the quinone direct dyes according to the invention o f formula (II) below, organic or mineral acid or base salts thereof, tautomeric forms, optical isomers or geometrical isomers thereo f, and/or so lvates thereo f:

(II) in which formula (II) n, R, R _{l s} R ₂ and X have the same meanings as those indicated in formula (I) . The compounds of leuco type according to the invention lead, in the presence of one or more oxidizing agents, to the quinone direct dyes o f formula (I) .

Thus, the invention also relates to the use of one or more compounds o f leuco type of formula (II) as precursors of the direct dyes o f formula (I) .

In particular, the invention relates to the use of one or more compounds o f leuco type o f formula (II) in the presence of one or more oxidizing agents, for dyeing keratin fibres, in particular human keratin fibres such as the hair.

The present invention also relates to a multi-compartment device or "kit" containing a first compartment comprising a cosmetic composition comprising one or more compounds of leuco type o f formula (II) as defined previously, and a second compartment comprising one or more oxidizing agents .

The compounds of leuco type of formula (II) used under oxidizing conditions thus have the advantage of giving colorations that are resistant to the various attacking factors to which keratin fibres may be subj ected, such as inclement weather, washing, light and perspiration.

Other characteristics, aspects, subj ects and advantages of the present invention will emerge even more clearly on reading the description and the examples that follow.

/. Quinone direct dyes

Preferably, in formula (I), quinone direct dyes according to the invention are such that, taken together or separately:

• n represents an integer equal to 0 , 1 or 2;

• R represents :

- a linear or branched C 1 - C4 alkyl radical, preferably methyl;

- a C 1 - C4 alkoxy radical, preferably a methoxy radical; - a halogen atom, preferably chlorine;

• Ri represents :

- a linear or branched C ₁ -C ₅ alkyl radical, preferably a methyl or ethyl radical;

- a linear or branched C ₁ -C ₅ alkyl radical, substituted with one or more hydroxyl radicals, preferably a 2- hydroxyethyl radical;

• R ₂ represents :

- a linear or branched C ₁ -C ₅ alkyl radical, preferably a methyl or ethyl radical;

- a linear or branched C ₁ -C ₅ alkyl radical, substituted with one or more hydroxyl radicals, preferably a 2- hydroxyethyl radical; and/or

• X represents :

- a hydroxyl radical;

- a radical -NR ₃ R ₄ in which R ₃ and R ₄ represent, independently o f each other:

^■ a hydrogen atom;

^■ a linear or branched C i -C ₆ alkyl radical;

" a linear or branched C i -C ₆ alkyl radical, substituted with one or more hydroxyl radicals .

An ^" denotes a cosmetically acceptable anion or mixture o f anions, for instance halides, such as chloride, methosulfates, nitrates; alkylsulfonates : Alk-S(0) ₂ 0 ^" such as methanesulfonate or mesylate, and ethanesulfonate; arylsulfonates : Ar-S(0) ₂ 0 ^" such as benzenesulfonate and toluenesulfonate or tosylate; citrate; succinate; tartrate; lactate; alkyl sulfates : Alk-0-S(0)0 ^" such as methylsulfate; arylsulfates such as benzenesulfate and toluenesulfate; phosphate; acetate; triflate; and borates such as tetrafluoroborate.

Preferably, An ^" is an anionic counterion chosen from bromide, chloride, and methylsulfate and toluenesulfonate ions or a mixture of these ions. Preferably, n represents an integer equal to 0 , 1 or 2 , and more particularly n is equal to 0 or 2.

Preferably, R represents a linear or branched C ₁ - C4 alkyl radical, a C ₁ - C4 alkoxy radical or a halogen atom. More preferentially, R is chosen from a methyl radical, a methoxy radical and a chlorine atom.

Preferably, Ri represents a linear or branched C ₁ - C ₅ alkyl radical and R ₂ represents a linear or branched C ₁ -C ₅ alkyl radical, substituted with one or more hydroxyl radicals, or vice versa.

More preferentially, Ri is chosen from a methyl radical and an ethyl radical, and R ₂ is a 2-hydroxyethyl radical, or vice versa.

Preferably, X represents a hydroxyl radical.

As a variant, X represents a radical -NR ₃ R ₄ in which R ₃ and R ₄ represent, independently o f each other, a hydrogen atom or a linear or branched C i -C ₆ alkyl radical, optionally substituted with one or more hydroxyl radicals.

Preferably, R ₃ and R ₄ represent, independently o f each other, a hydrogen atom or a methyl, ethyl, isopropyl or 2-hydroxyethyl radical.

According to one embodiment, n represents an integer equal to 0, 1 or 2 and Ri represents a linear or branched C ₁ -C ₅ alkyl radical and R ₂ represents a linear or branched C ₁ -C ₅ alkyl radical, substituted with one or more hydroxyl radicals, or vice versa.

In accordance with this embodiment, n is preferably equal to 2, Ri is chosen from a methyl radical and an ethyl radical, and R ₂ is a 2- hydroxyethyl radical, or vice versa.

In particular, n is equal to 2, R represents a linear or branched C ₁ -C ₄ alkyl radical or a C ₁ -C ₄ alkoxy radical and Ri is chosen from a methyl radical and an ethyl radical and R ₂ is a 2-hydroxyethyl radical, or vice versa.

According to another embodiment, n is equal to 0 and Ri represents a linear or branched C ₁ -C ₅ alkyl radical and R ₂ represents a linear or branched C ₁ -C ₅ alkyl radical, substituted with one or more hydroxyl radicals, or vice versa. According to another embodiment, n is equal to 1 and Ri represents a linear or branched C ₁ -C ₅ alkyl radical and R ₂ represents a linear or branched C ₁ -C ₅ alkyl radical, substituted with one or more hydroxyl radicals, or vice versa.

Preferably, the quinone direct dyes of formula (I) according to the invention are chosen from the fo llowing compounds and the geometrical or optical isomer forms thereof, the tautomers thereof, the organic or mineral acid or base salts thereof or the solvates thereo f such as hydrates :

Compound 7

H

2-(4-Amino-3-methylphenylamino)- 5- [(2-

² 1 hydro xyethyl)methylamino] [1 ,4]

CH ₃

benzoquinone

Compound 8

OH

2-(4-Amino-2,3,5,6- tetramethylphenylamino)-5-[(2- hydroxyethyl)methylamino] [1 ,4] benzoquinone

Compound 9

Compound 11

2-(4-Aminophenylamino)-5-[(2- hydroxyethyl)ethylamino] [ 1 ,4] benzoquinone

Compound 12

2-[(2-Hydroxyethyl)ethylamino]-5- (4-hydroxyphenylamino)[ 1 ,4] benzoquinone

Compound 13

"xxfxxr 2-{4-[Bis(2- hydro xy ethyl) amino Jphenylamino} -5-[(2-hydroxyethyl) ethylamino] [ 1 ,4]benzoquinone

OH

Compound 14 2-(3-Chloro-4- hydroxyphenylamino)- 5-[(2- hydroxyethyl)ethylamino] [ 1 ,4]ben- zoquinone

quinone

2-(4-Amino-2-methoxy-5- methylphenylamino)-5-[(2- hydroxyethyl)methylamino] [1 ,4] benzoquinone

with An ^" as defined previously

2-Dimethylamino-5-(4- hydroxyphenylamino)[ 1 ,4] benzoquinone

Compound 28

2-(4-Aminophenylamino)-5- dimethylamino[ 1 ,4]benzoquinone

Compound 29

2-(4-Amino-2,3- dimethylphenylamino)-5- dimethylamino[ 1 ,4]benzoquinone

Compound 30

2-Dimethylamino-5-[4- (ethylisopropylamino)phenyl- amino] [1 ,4]benzoquinone

Compound 31

Preferably, the direct dyes of formula (I) according to the present invention are chosen from the quinone direct dyes 1 , 2 , 3 , 4 , 5 , 6, 7, 8 , 9, 10, 1 1 , 19, 20, 21 , 22, 23 , 24, 25 , 32 and 33.

Even more preferentially, the quinone direct dyes of formula

(I) according to the invention are chosen from the quinone direct dyes 1 , 2, 3 , 4, 7, 10, 1 1 and 32.

The quinone direct dyes of formula (I) may be obtained

The compounds corresponding to formula (I) are generally obtained by reacting the derivatives l a with the morpholine derivatives 2 in basic medium in the presence of an oxidizing agent. The base used is preferentially an aqueous so lution of ammonia or of sodium hydroxide and the oxidizing agent is preferentially chosen from hydrogen peroxide, potassium ferricyanide, air, ammonium persulfate and manganese oxide.

Synthetic approaches similar to that described previously are described in patents FR 2 234 277, FR 2 047 932, FR 2 106 661 and FR 2 121 101 .

The quinone direct dyes of formula (I) may also be obtained according to the procedure as described below :

The compounds corresponding to formula (I) are generally obtained by reacting the derivatives l a or I d with the meta- aminopheno ls 3 in basic medium in the presence o f an oxidizing agent. The base used is preferentially an aqueous so lution o f ammonia or of sodium hydroxide and the oxidizing agent is preferentially chosen from hydrogen peroxide, potassium ferricyanide, air, ammonium persulfate and manganese oxide.

Similar synthetic approaches are described in patent application FR 21 189380.

The invention also relates to the use of one or more quinone direct dyes of formula (I) as described previously for dyeing keratin fibres, in particular human keratin fibres such as the hair. //. Dye composition

The present invention also relates to a composition for dyeing keratin fibres, in particular human keratin fibres such as the hair, comprising, in a suitable dyeing medium, one or more direct dyes of formula (I) as defined previously.

Preferably, the dye composition comprises one or more quinone direct dyes o f formula (I) chosen from compounds 1 , 2, 3 , 4, 5 , 6, 7, 8 , 9, 10, 1 1 , 19, 20, 21 , 22, 23 , 24, 25 , 32 and 33 , and also mixtures thereof.

Even more preferentially, the dye composition comprises one or more quinone direct dyes of formula (I) chosen from compounds 1 ,

2, 3 , 4, 7, 10, 1 1 and 32, and mixtures thereof.

The direct dye(s) as defined previously may be present in the dye composition according to the invention in a content ranging from 0.001 % to 10% by weight and preferably in a content ranging from

0.005 %) to 6%o by weight, relative to the total weight of the dye composition.

The dye composition o f the invention may also comprise one or more oxidation dyes. The oxidation dyes are generally chosen from oxidation bases optionally combined with one or more couplers .

By way of example, the oxidation bases are chosen from para- phenylenediamines, bis (phenyl) alky lenedi amines, par a- amino pheno ls, ortho-aminopheno ls and heterocyclic bases, and the addition salts thereo f.

Among the para-phenylenediamines that may be mentioned, for example, are para-phenylenediamine, para-tolylenediamine, 2-chloro- para-phenylenediamine, 2,3 -dimethyl-para-phenylenediamine, 2,6- dimethyl-para-phenylene diamine, 2,6-diethyl-para-phenylenediamine, 2,5 -dimethyl-para-phenylenediamine, N, N- dimethyl-par a- phenylenediamine, Ν,Ν-diethyl-para-phenylenediamine, N,N-dipropyl- para-phenylenediamine, 4 - amino -N,N- diethyl- 3 -methylaniline, N,N- bis( -hydroxyethyl)-para-phenylenediamine, 4-N,N-bis(P- hydroxy ethyl) amino -2 -methylaniline, 4-N,N-bis( - hy droxy ethyl) amino -2 -chloro aniline, 2- -hydroxyethyl-para- phenylenediamine, 2- fluoro -para-phenylenediamine, 2-isopropyl-para- phenylenediamine, N-( -hydroxypropyl)-para-phenylenediamine, 2- hydroxymethyl-para-phenylenediamine, N, N- dimethyl- 3 -methyl-par a- phenylenediamine, N-ethyl-N-( -hy droxy ethyl) -para- phenylenediamine, N-( ,y-dihydroxypropyl)-para-phenylenediamine, N- (4 ' -amino phenyl) -para-phenylenediamine, N-phenyl-para- phenylenediamine, 2- -hydroxyethyloxy-para-phenylenediamine, 2-β- acetylaminoethyloxy-para-phenylenediamine, N- (β-methoxy ethyl) - para-phenylenediamine, 4-aminophenylpyrrolidine, 2-thienyl-para- phenylenediamine, 2- -hydroxyethylamino-5 -aminotoluene and 3 - hydroxy- l -(4 ' -aminophenyl)pyrrolidine, and addition salts thereof with an acid.

Preference is particularly given, among the abovementioned para-phenylenediamines, to para-phenylenediamine, para- tolylenediamine, 2-isopropyl-para-phenylenediamine, 2-(β- hy droxy ethyl) -para-phenylenediamine, 2-( -hy droxy ethylo xy) -para- phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,6-diethyl- para-phenylenediamine, 2,3 -dimethyl-para-phenylenediamine, N,N- bis( -hydroxyethyl)-para-phenylenediamine, 2-chloro-para- phenylenediamine, 2-( -acetylamino ethyloxy)-para-phenylenediamine and their addition salts with an acid.

Among the bis(phenyl)alkylenediamines that may be mentioned, for example, are N,N'-bis( -hydroxyethyl)-N,N'-bis(4'- aminophenyl)- l ,3 -diaminopropanol, N,N'-bis( -hydroxyethyl)-N,N'- bis (4 '-aminophenyl) ethylene diamine, N,N'-bis(4- aminophenyl)tetramethylenediamine, N, N'-bis( -hydroxy ethyl) -N,N '- bis(4- amino phenyl)tetramethylenediamine, N,N'-bis(4- methylaminophenyl)tetramethylenediamine, N,N'-bis(ethyl)-N,N'- bis(4'-amino-3 '-methylphenyl)ethylenediamine and l , 8-bis(2,5 - diaminophenoxy)-3 ,6-dioxaoctane, and the addition salts thereo f.

Mention may be made, among para-aminophenols, by way of example, of para-aminophenol, 4-amino-3 -methylpheno l, 4-amino-3 - fluorophenol, 4-amino-3 -chlorophenol, 4-amino-3 -

(hydroxymethyl)phenol, 4-amino-2-methylpheno l, 4-amino-2- (hydroxymethyl)phenol, 4-amino-2-(methoxymethyl)phenol, 4 -amino - 2-(aminomethyl)phenol, 4-amino -2 - [(β- hydroxyethyl)aminomethyl]phenol, 4-amino-2-fluoropheno l and their addition salts with an acid.

Mention may be made, among ortho-aminopheno ls, by way o f example, of 2-aminophenol, 2-amino-5 -methylpheno l, 2-amino-6- methylpheno l, 5 -acetamido-2-aminopheno l and their addition salts.

Mention may be made, among heterocyclic bases, by way o f example, of pyridine derivatives, pyrimidine derivatives and pyrazole derivatives.

Mention may be made, among pyridine derivatives, o f the compounds described, for examp le, in patents GB 1 026 978 and GB 1 153 196, such as 2,5 -diaminopyridine, 2-(4- methoxyphenyl)amino-3 -aminopyridine, 3 ,4-diaminopyridine and their addition salts.

Other pyridine oxidation bases o f use in the present invention are the 3 -aminopyrazolo [ 1 ,5 -a]pyridine oxidation bases or their addition salts described, for example, in patent application FR 2 80 1 308. Mention may be made, by way of example, of pyrazolo[ 1 ,5- a]pyrid-3-ylamine, 2-(acetylamino)pyrazolo[ 1 ,5-a]pyrid-3-ylamine, 2- (morpholin-4-yl)pyrazolo[ 1 ,5-a]pyrid-3-ylamine, 3- aminopyrazolo[ 1 ,5-a]pyridine-2-carboxylic acid, 2- methoxypyrazolo[ 1 ,5-a]pyrid-3-ylamine, (3-aminopyrazolo[l,5- a]pyrid-7-yl)methanol, 2-(3-aminopyrazolo[ 1 ,5-a]pyrid-5-yl)ethanol, 2-(3-aminopyrazolo[ 1 ,5-a]pyrid-7-yl)ethanol, (3-aminopyrazolo[ 1 ,5- a]pyrid-2-yl)methanol, 3,6-diaminopyrazolo[ 1 ,5-a]pyridine, 3,4- diaminopyrazolo[ 1 ,5-a]pyridine, pyrazolo[l ,5-a]pyridine-3,7-diamine, 7-(morpholin-4-yl)pyrazolo[l ,5-a]pyrid-3-ylamine, pyrazolo[l ,5- a]pyridine-3, 5 -diamine, 5-(morpholin-4-yl)pyrazolo[l ,5-a]pyrid-3- ylamine, 2-[(3-aminopyrazolo[ 1 ,5-a]pyrid-5-yl)(2- hydroxyethyl)amino]ethanol, 2-[(3-aminopyrazolo[ 1 ,5-a]pyrid-7-yl)(2- hydroxyethyl)amino]ethanol, 3-aminopyrazolo[ 1 ,5-a]pyrid-5-ol, 3- aminopyrazolo[ 1 ,5-a]pyrid-4-ol, 3-aminopyrazolo[ 1 ,5-a]pyrid-6-ol, 3- aminopyrazolo[ 1 ,5-a]pyrid-7-ol and their addition salts.

Mention may be made, among pyrimidine derivatives, of the compounds described, for example, in patents DE 2359399, JP 88- 169571, JP 05-63124 and EP 0 770 375 or patent application WO 96/15765, such as 2,4,5,6-tetraaminopyrimidine, 4-hydroxy-2,5,6- triaminopyrimidine, 2-hydroxy-4,5,6-triaminopyrimidine, 2,4- dihydroxy-5,6-diaminopyrimidine, 2,5,6-triaminopyrimidine and their addition salts and their tautomeric forms, when a tautomeric equilibrium exists.

Mention may be made, among pyrazole derivatives, of the compounds described in patents DE 3843892 and DE 4133957 and patent applications WO 94/08969, WO 94/08970, FR-A-2733 749 and DE 19543988, such as 4,5-diamino- 1 -methylpyrazole, 4,5-diamino- 1 - ( -hydroxyethyl)pyrazole, 3,4-diaminopyrazole, 4,5-diamino- 1 -(4 '- chlorobenzyl)pyrazole, 4,5-diamino- 1 ,3-dimethylpyrazole, 4,5- diamino -3 -methyl- 1 -phenylpyrazole, 4,5-diamino - 1 -methyl- 3- phenylpyrazole, 4 -amino - 1 ,3-dimethyl-5-hydrazinopyrazole, 1 -benzyl- 4, 5 -diamino -3 -methylpyrazole, 4,5-diamino-3-(tert-butyl)- 1 - methylpyrazole, 4,5-diamino- 1 -(tert-butyl)-3 -methylpyrazole, 4,5- diamino- 1 - (β-hydroxy ethy l)-3 -methylpyrazole, 4,5-diamino - 1 - ethy 1-3- methylpyrazole, 4,5-diamino - 1 - ethy 1-3- (4'-methoxyphenyl)pyrazole, 4,5-diamino - 1 - ethy 1-3 -(hydroxymethyl)pyrazole, 4, 5 -diamino -3- hydroxymethyl- 1 -methylpyrazole, 4,5-diamino-3-hydroxymethyl- 1 - isopropylpyrazole, 4,5-diamino-3-methyl- 1 -isopropylpyrazole, 4- amino-5-(2'-aminoethyl)amino- 1 ,3-dimethylpyrazole, 3,4,5- triaminopyrazole, 1 -methyl-3,4,5-triaminopyrazole, 3,5-diamino- 1 - methyl-4-(methylamino)pyrazole, 3,5-diamino-4-( - hydroxyethyl)amino- 1 -methylpyrazole and their addition salts. 4,5- Diamino- 1 -( -methoxyethyl)pyrazole may also be used.

Use will preferably be made of a 4,5-diaminopyrazole and even more preferentially of 4,5-diamino- 1 -( -hydroxyethyl)pyrazole and/or a salt thereof.

Mention may also be made, as pyrazole derivatives, of diamino-N,N-dihydropyrazolopyrazolones and in particular those described in application FR-A-2886 136, such as the following compounds and their addition salts: 2,3-diamino-6,7-dihydro-lH,5H- pyrazolo[ 1 ,2-a]pyrazol- 1 -one, 2-amino-3-ethylamino-6,7-dihydro- lH,5H-pyrazolo[ 1 ,2-a]pyrazol- 1 -one, 2-amino-3-isopropylamino-6,7- dihydro- lH,5H-pyrazolo[ 1 ,2-a]pyrazol- 1 - one, 2-amino-3-(pyrrolidin- l-yl)-6,7-dihydro-lH,5H-pyrazolo[l,2-a]pyrazol-l-one, 4, 5 -diamino - 1 ,2-dimethyl-l ,2-dihydropyrazol-3-one, 4,5-diamino- 1 ,2-diethyl- 1 ,2- dihydropyrazol-3-one, 4,5-diamino- 1 ,2-di(2-hydroxy ethyl)- 1 ,2- dihydropyrazol-3-one, 2-amino-3-(2-hydroxyethyl)amino-6,7-dihydro- lH,5H-pyrazolo[ 1 ,2-a]pyrazol- 1 -one, 2-amino-3-dimethylamino-6,7- dihydro-lH,5H-pyrazolo[ 1 ,2-a]pyrazol- 1 -one, 2,3-diamino-5,6,7,8- tetrahydro- lH,6H-pyridazino[ 1 ,2-a]pyrazol- 1 -one, 4 -amino - 1 ,2- diethyl-5-(pyrrolidin-l-yl)-l ,2-dihydropyrazol-3-one, 4- amino -5 -(3 - dimethylaminopyrrolidin- 1 -yl)- 1 ,2-diethyl- 1 ,2-dihydropyrazol-3-one or 2,3-diamino-6-hydroxy-6,7-dihydro-lH,5H-pyrazolo[ 1 ,2-a]pyrazol- 1-one.

Use will preferably be made of 2,3-diamino-6,7-dihydro- lH,5H-pyrazolo[l,2-a]pyrazol-l-one and/or one of its salts. Use will preferably be made, as heterocyclic bases, of 4,5- diamino- 1 - ( -hydroxyethyl)pyrazole and/or 2,3-diamino-6,7-dihydro- lH,5H-pyrazolo[l,2-a]pyrazol-l-one and/or one of their salts.

The dye composition may optionally comprise one or more couplers advantageously chosen from those conventionally used for the dyeing of keratin fibres.

Among these couplers, mention may be made especially of meta-phenylenediamines, meta-aminophenols, meta-diphenols, naphthalene-based couplers and heterocyclic couplers, and also the addition salts thereof.

Mention may be made, for example, of 1 ,3-dihydroxybenzene, 1 ,3-dihydroxy-2-methylbenzene, 4-chloro - 1 ,3-dihydroxybenzene, 2,4- diamino- 1 - (P-hydroxyethyloxy)benzene, 2 -amino -4- (β- hydroxyethylamino)- 1 -methoxybenzene, 1 ,3-diaminobenzene, 1,3- bis(2,4-diaminophenoxy)propane, 3-ureidoaniline, 3-ureido-l- dimethylaminobenzene, sesamol, l-P-hydroxyethylamino-3,4- methylenedioxybenzene, cc-naphthol, 2-methyl- 1 -naphthol, 6- hydroxyindole, 4-hydroxyindole, 4-hydroxy-N-methylindole, 2-amino- 3-hydroxypyridine, 6-hydroxybenzomorpholine, 3,5-diamino-2,6- dimethoxypyridine, l-N-(P-hydroxyethyl)amino-3,4- methylenedioxybenzene, 2,6-bis(P-hydroxyethylamino)toluene, 6- hydroxyindoline, 2,6-dihydroxy-4-methylpyridine, l-H-3- methylpyrazol-5-one, 1 -phenyl-3-methylpyrazol-5-one, 2,6- dimethylpyrazolo[ 1 ,5-b]-l ,2,4-triazole, 2,6-dimethyl[3,2-c]- 1 ,2,4- triazole and 6-methylpyrazolo[ 1 ,5-a]benzimidazole, the addition salts thereof with an acid, and mixtures thereof.

In general, the addition salts of the oxidation bases and couplers which can be used in the context of the invention are chosen in particular from the addition salts with an acid, such as the hydrochlorides, hydrobromides, sulfates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, phosphates and acetates.

The oxidation base(s) each advantageously represent from 0.001% to 10% by weight and preferably from 0.005% to 6% by weight relative to the total weight of the composition. The content of coupler(s), if they are present, each advantageously represent from 0.001 % to 10% by weight relative to the total weight of the composition, and preferably from 0.005 % to 6% by weight relative to the total weight of the dye composition.

The dye composition according to the invention may also comprise one or more additional direct dyes other than the quinone direct dyes according to the present invention.

The additional direct dye(s) according to the invention are chosen from neutral, acidic or cationic nitrobenzene dyes, neutral, acidic or cationic azo direct dyes, neutral, acidic or cationic quinone and in particular anthraquinone direct dyes other than those of the present invention, azine direct dyes, triarylmethane direct dyes, azomethine direct dyes and natural direct dyes .

Among the benzenic direct dyes that may be used according to the invention, mention may be made in a non-limiting manner o f the fo llowing compounds :

- 1 ,4-diamino-2-nitrobenzene;

- 1 -amino-2-nitro-4-B-hydroxyethylaminobenzene;

- 1 - amino -2 -nitro -4 -bis( - hydroxy ethyl) aminobenzene;

- 1 ,4-bis(B-hydroxyethylamino)-2-nitrobenzene;

- 1 -B-hydroxyethylamino-2-nitro-4-bis( - hydroxyethylamino)benzene;

- 1 -B-hydroxyethylamino-2-nitro-4-aminobenzene;

- 1 - β -hydroxy ethylamino -2 -nitro -4 -(ethyl) (fitly droxy ethyl) aminobenzene;

- 1 - amino-3 -methyl-4- -hydroxyethylamino -6-nitrobenzene;

- 1 - amino-2-nitro-4- -hydroxyethylamino-5 -chlorobenzene;

- 1 ,2-diamino-4-nitrobenzene;

- 1 - amino -2- β -hydro xyethylamino- 5 -nitrobenzene;

- 1 ,2-bis( -hydroxyethylamino)-4-nitrobenzene;

- 1 -amino-2-tris(hydroxymethyl)methylamino-5 -nitrobenzene;

- 1 -hydro xy-2- amino -5 -nitrobenzene;

- 1 -hydro xy-2 -amino -4 -nitrobenzene;

- 1 -hydroxy- 3 -nitro -4 -amino benzene; - 1 -hydroxy-2-amino-4,6-dinitrobenzene;

- 1 -β-hydroxyethy loxy-2- -hydroxyethylamino -5 -nitrobenzene;

- 1 -met hoxy-2- -hydroxyet hylamino- 5 -nitrobenzene;

- 1 - β -hy droxyethyloxy- 3 -met hylamino -4 -nitrobenzene;

- 1 - ,y-dihydroxypropyloxy-3 -methylamino-4-nitrobenzene;

- 1 - -hydroxyethylamino-4- ,y-dihydroxypropyloxy-2- nitrobenzene;

- 1 - ,y-dihydroxypropylamino-4-trifluoromethyl-2- nitrobenzene;

- 1 - -hydroxyethylamino-4-trifluoromethyl-2-nitrobenzene;

- 1 - β -hydroxyet hylamino- 3 -methy 1-2 -nitrobenzene;

- 1 - -amino ethylamino-5 -methoxy-2-nitrobenzene;

- 1 -hydro xy-2-chloro-6-ethylamino-4-nitrobenzene;

- 1 -hydro xy-2-chloro-6-amino-4-nitrobenzene;

- 1 -hy dro xy- 6 -bis( -hydroxyethyl)amino- 3 -nitrobenzene;

- 1 - -hydroxyethylamino-2-nitrobenzene; and

- 1 -hydro xy-4- -hydroxyethylamino- 3 -nitrobenzene.

Among the azo direct dyes that may be used according to the invention, mention may be made of the cationic azo dyes described in patent applications WO 95/ 15 144, WO-95/0 1772 and EP-714954, the content of which forms an integral part of the invention.

Among these compounds, the ones that may be mentioned most particularly are the fo llowing dyes :

1 ,3 -dimethyl-2- [ [4-(dimethylamino)phenyl] azo] - 1 H- imidazo lium chloride,

1 ,3 -dimethyl-2- [(4-aminophenyl)azo] - l H-imidazo lium

chloride,

- 1 -methyl-4- [(methylphenylhydrazono)methyl]pyridinium methyl sulfate.

Among the azo direct dyes that may also be mentioned are the fo llowing dyes, described in the Colour Index International, 3rd edition: Disperse Red 17, Acid Yellow 9, Acid Black 1 , Basic Red 22, Basic Red 76, Basic Red 5 1 , Basic Yellow 57, Basic Brown 16, Acid Yellow 36, Acid Orange 7, Acid Red 33, Acid Red 35, Basic Brown 17, Acid Yellow 23, Acid Orange 24, Disperse Black 9.

Mention may also be made of 1 -(4 '-aminodiphenylazo)-2- methyl-4-bis( -hydroxyethyl)aminobenzene and 4-hydroxy-3-(2- methoxyphenylazo)- 1 -naphthalenesulfonic acid.

Among the quinone direct dyes, mention may be made of the following dyes: Disperse Red 15, Solvent Violet 13, Acid Violet 43, Disperse Violet 1, Disperse Violet 4, Disperse Blue 1, Disperse Violet 8, Disperse Blue 3, Disperse Red 11, Acid Blue 62, Disperse Blue 7, Basic Blue 22, Disperse Violet 15, Basic Blue 99, and also the following compounds:

1 -N-methylmorpholiniumpropylamino-4-hydroxyanthraquinone

1 -aminopropylamino-4-methylaminoanthraquinone

1 -aminopropylaminoanthraquinone

-5" -hydroxyethyl- 1 ,4-diaminoanthraquinone

-2-aminoethylaminoanthraquinone

1 ,4-bis( ,y-dihydroxypropylamino)anthraquinone.

Among the azine dyes, mention may be made of the following compounds: Basic Blue 17, Basic Red 2.

Among the triarylmethane dyes that may be used according to the invention, mention may be made of the following compounds: Basic Green 1, Acid Blue 9, Basic Violet 3, Basic Violet 14, Basic Blue 7, Acid Violet 49, Basic Blue 26, Acid Blue 7.

Among the azomethine dyes that may be used according to the invention, mention may be made of the following compounds:

-2- -hydroxyethlyamino-5-[bis( -4'- hydroxyethyl)amino]anilino- 1 ,4-benzoquinone;

-2- -hydroxyethylamino-5-(2'-methoxy-4 '- amino) anilino- 1 ,4- benzoquinone;

-3-N-(2'-chloro-4'-hydroxy)phenylacetylamino-6-methoxy- 1 ,4- benzoquinone imine;

-3-N-(3 '-chloro-4'-methylamino)phenylureido-6-methyl- 1 ,4- benzoquinone imine; and - 3 - [4 ' -N- (ethyl, carb amy lmethyl) amino ]phenylureido- 6 -met hyl- 1 ,4-benzoquinoneimine.

Among the natural direct dyes that may be used according to the invention, mention may be made o f lawsone, juglone, alizarin, purpurin, carminic acid, kermesic acid, purpurogallin, protocatechaldehyde, indigo, isatin, curcumin, spinulosin and apigenidin. Extracts or decoctions containing these natural dyes and in particular henna-based poultices or extracts may also be used.

The additional direct dye(s) may be present in the dye composition in a content ranging from 0.001 % to 10% by weight and preferably in a content ranging from 0.005 % to 6% by weight, relative to the total weight of the composition.

Preferably, the dye composition comprises one or more quinone direct dyes o f formula (I) and one or more azomethine direct dyes.

The medium that is suitable for dyeing, also known as the dye support, is a cosmetic medium generally formed from water or a mixture of water and of at least one organic so lvent. Examples of organic so lvents that may be mentioned include C 1 - C 4 lower alkano ls, such as ethano l and isopropano l; po lyols and po lyo l ethers, for instance 2-butoxyethano l, propylene glycol, propylene glyco l monomethyl ether, diethylene glyco l monoethyl ether and monomethyl ether, and also aromatic alcoho ls, for instance benzyl alcoho l or phenoxyethano l, and mixtures thereof.

When they are present, the solvents are present in proportions preferably of between 1 % and 99% by weight approximately and even more preferentially between 5 % and 95 % by weight approximately relative to the total weight of the dye composition.

The dye composition may also contain various adjuvants conventionally used in hair dye compositions, such as anionic, cationic, nonionic or amphoteric surfactants or mixtures thereof, anionic, cationic, nonionic or amphoteric polymers or mixtures thereo f, mineral or organic thickeners, and in particular anionic, cationic, nonionic and amphoteric polymeric associative thickeners, antioxidants, penetrants, sequestrants, fragrances, buffers, dispersants, so lubilizers, conditioning agents, for instance vo latile or non- vo latile, modified or unmodified silicones such as amino silicones, film- forming agents, ceramides, preserving agents and opacifiers .

The above adjuvants are generally present in an amount, for each o f them, o f between 0.01 % and 20% by weight relative to the weight of the composition.

Needless to say, a person skilled in the art will take care to select this or these optional additional compound(s) such that the advantageous properties intrinsically associated with the dye composition in accordance with the invention are not, or are not substantially, adversely affected by the envisaged addition(s).

The pH of the dye composition in accordance with the invention is generally between 3 and 12 approximately, particularly between 5 and 1 1 approximately and even more particularly from 6 to 9.

Preferably, the pH of the dye composition in accordance with the invention ranges from 9 to 12, more preferably from 9 to 1 0.

It may be adjusted to the desired value by means of acidifying or basifying agents commonly used in the dyeing of keratin fibres, or alternatively using standard buffer systems .

Among the acidifying agents that may be mentioned, for example, are mineral or organic acids, for instance hydrochloric acid, orthophosphoric acid or sulfuric acid, carboxylic acids, for instance acetic acid, tartaric acid, citric acid and lactic acid, and sulfonic acids.

Among the basifying agents that may be mentioned, for example, are aqueous ammonia, alkali metal carbonates, alkanolamines such as monoethanolamine, diethanolamine and triethano lamine, and also derivatives thereo f, sodium hydroxide, potassium hydroxide and the compounds o f formula (III) below: Rd (III)

in which W is a propylene residue optionally substituted with a hydroxyl group or a C ₁ -C ₄ alkyl radical; and R _a , R _b , R _c and R _d , which may be identical or different, represent a hydrogen atom or a C ₁ -C ₄ alkyl or C ₁ -C ₄ hydroxyalkyl radical.

The dye composition according to the invention may be in various forms, such as in the form o f liquids, creams or gels, or in any other form that is suitable for dyeing keratin fibres, and especially human hair.

As indicated previously, the invention also relates to the use o f the dye composition as defined previously for dyeing keratin fibres, in particular human keratin fibres such as the hair.

III. Dyeing process

The dyeing process according to the present invention consists in applying to wet or dry keratin fibres a dye composition as defined previously for a time that is sufficient to obtain the desired coloration, and the fibres are then rinsed, optionally washed with shampoo and rinsed again, and the resulting fibres are dried or left to dry.

Preferably, the leave-on time for the dye composition is between 1 and 60 minutes, preferably between 5 and 40 minutes and even more preferably between 10 and 30 minutes .

The dye composition is generally applied to the keratin fibres at room temperature, preferably between 25 and 55 °C .

According to one embodiment, the dye composition according to the invention is applied to the keratin fibres in the presence o f one or more oxidizing agents for a time that is sufficient to obtain the desired lightening.

The oxidizing agent may be present in the dye composition or may be used separately in a cosmetic composition.

Preferably, the oxidizing agent is used separately in a cosmetic composition. Thus, the present invention also relates to a process for lightening keratin fibres, in particular human keratin fibres such as the hair, in which (i) the dye composition as defined previously, free o f oxidizing agent, and (ii) a cosmetic composition comprising one or more oxidizing agents are applied to the said fibres; compositions (i) and (ii) being applied to the said keratin fibres sequentially or simultaneously for a time that is sufficient to obtain the desired lightening, and the fibres are then rinsed, optionally washed with shampoo and rinsed again, and the resulting fibres are dried or left to dry.

The purposes of the present invention, the term " sequentially" means that the oxidizing composition is applied before or after the dye composition, i.e. as a pretreatment or a post-treatment.

The oxidizing agents used are chosen from hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulfates, peracids, and oxidase enzymes (with the possible cofactors thereof), among which mention may be made o f peroxidases, 2-electron oxidoreductases such as uricases, and 4-electron oxygenases, for instance laccases.

The oxidizing agent is preferably hydrogen peroxide.

The oxidizing composition may also contain various adjuvants conventionally used in compositions for dyeing the hair and as defined previously.

The pH o f the oxidizing composition containing the oxidizing agent is such that, after mixing with the dye composition, the pH of the resulting composition applied to the keratin fibres preferably ranges between 3 and 12 approximately, even more preferentially between 5 and 1 1 and even more particularly between 6 and 8.5. It may be adjusted to the desired value by means of acidifying or basifying agents usually used in the dyeing o f keratin fibres and as defined previously. IV. Compound of leuco type

The present invention also relates to compounds of leuco type of formula (II) below, organic or mineral acid or base salts thereof, tautomeric forms, optical isomers or geometrical isomers thereo f and/or solvates thereof:

in which n, R, R _{l s} R ₂ and X have the same meanings as those indicated in formula (I) .

In particular, the preferred variants of n, R, R _{l s} R ₂ and X in formula (II) of the compounds of leuco type correspond to those indicated in formula (I) of the direct dyes .

The compounds o f leuco type corresponding to formula (II) are generally obtained by reacting the compounds o f quinone type o f formula (I) with a reducing agent according to the reaction scheme below :

Synthetic approaches similar to this scheme are described in patent applications FR 2 056 799, FR 2 047 932, FR 2 165 965 and FR 2 262 023.

The compounds o f leuco type o f formula (II) are used as precursors of the direct dyes of formula (I) . Preferably, the compounds of leuco type of formula (II) are chosen from the compounds corresponding to the reduced form of the quinone direct dyes 1 to 33 mentioned previously.

In other words, the compounds of leuco type of formula (II) are chosen from the precursors of the quinone direct dyes 1 to 33.

Even more preferentially, the compounds of leuco type o f formula (II) are chosen from precursors of the direct dyes 1 , 2, 3 , 4, 5 , 6, 7, 8 , 9, 10, 1 1 , 19, 20, 21 , 22, 23 , 24, 25 , 32 and 33 and preferentially the precursors of the quinone direct dyes 1 , 2, 3 , 4 , 7, 10, 1 1 and 32.

In particular, the invention relates to a cosmetic composition comprising one or more compounds of leuco type of formula (II) as defined previously.

The present invention also relates to a dyeing process in which a cosmetic composition comprising one or more compounds of leuco type of the abovementioned formula (II) is applied to keratin fibres in the presence of one or more oxidizing agents for a time that is sufficient to develop the desired coloration, after which the fibres are rinsed, optionally washed with shampoo and rinsed again, and the resulting fibres are dried or left to dry.

The oxidizing agent may be atmospheric oxygen or may be chosen from the oxidizing agents mentioned previously.

In particular, when the oxidizing agent is atmospheric oxygen, simple exposure to air of the keratin fibres treated with the composition comprising the compound(s) of leuco type makes it possible to generate the colouring species and, consequently, to colour the fibres.

According to one variant, the oxidizing agent(s) may be applied simultaneously or sequentially to the cosmetic composition comprising the compounds o f leuco type.

Thus, the cosmetic composition comprising the oxidizing agent(s) may be applied to the keratin fibres before, simultaneously with or after the cosmetic composition comprising the compounds o f leuco type of formula (II) according to the invention. According to another variant, a ready-to-use composition which results from the mixing of a cosmetic composition comprising one or more compounds of leuco type of the abovementioned formula (II) and of a cosmetic composition comprising one or more oxidizing agents is applied to the keratin fibres .

According to one embodiment, the invention relates to a composition, in particular for dyeing keratin fibres such as the hair, comprising one or more compounds of formula (II) as defined previously and optionally comprising one or more oxidizing agents .

The ready-to-use composition that is thus applied to the keratin fibres may be in various forms, such as in the form o f liquids, creams or gels, or in any other form that is suitable for dyeing keratin fibres, and in particular human hair.

The leave-on time for the composition(s) ranges from 1 to 60 minutes, preferably from 5 to 40 minutes and even more preferentially from 10 to 30 minutes.

The cosmetic composition comprising such compounds o f leuco type is generally applied to the keratin fibres at room temperature, preferably between 25 and 55 ° C .

IV. Dyeing device

The present invention also relates to a multi-compartment device or "kit" comprising a first compartment containing a cosmetic composition comprising one or more compounds of formula (I) as defined previously or containing one or more compounds of leuco type of formula (III) as defined previously, and optionally a second compartment comprising one or more oxidizing agents .

In particular, the invention relates to a multi-compartment dyeing device or "kit" comprising a first compartment containing a cosmetic composition comprising one or more direct dyes of formula (I) as defined previously or containing one or more compounds o f leuco type of formula (III) as defined previously, and a second compartment comprising one or more oxidizing agents . More particularly, the invention relates to a multi-compartment dyeing device or "kit" comprising a first compartment containing a cosmetic composition comprising one or more direct dyes of formula (I) as defined previously, free of oxidizing agent, and a second compartment containing a cosmetic composition comprising one or more oxidizing agents.

The invention also relates to a multi-compartment dyeing device or "kit" comprising a first compartment containing a cosmetic composition comprising one or more compounds of leuco type of the abovementioned formula (II), and a second compartment containing a cosmetic composition comprising one or more oxidizing agents.

According to one particular embodiment, the device may comprise at least one compartment comprising a cosmetic composition comprising one or more compounds of leuco type of the abovementioned formula (II) .

In this case, the composition comprising the compound(s) of leuco type as defined above is applied to the keratin fibres, which become co loured due to their exposure to air.

The devices mentioned above are suitable for dyeing keratin fibres.

The evaluation o f the co loration can be done visually or read on a spectrocolorimeter (such as Minolta CM3600d, illuminant D65 , angle 10° , SCI values) for the L ^* , a ^* , b ^* colorimetric measurements . In this L ^* , a ^* , b ^* system, L ^* represents the intensity o f the co lor, a ^* indicates the green/red co lor axis and b ^* indicates the blue/yellow co lor axis. The lower the value of L, the darker or more intense the co lor is. The higher the value o f a , the redder the shade is; the higher the value o f b , the yellower the shade is.

The variation in co loring between the colored locks of natural white hair which is untreated (control) and after treatment or co loration is defined by ΔΕ , corresponding to the color uptake on keratin fibers, according to the fo llowing equation: ΔΕ* = - (L ^* — L _o ^* ) ² +(a ^* — a ₀ ^* f + ( b ^* - b ₀ ^* ) ² (i)

In this equation, L ^* , a ^* and b ^* represent the values measured after dyeing the natural hair comprising 90% of white hairs and Lo , ao and bo represent the values measured for the untreated natural hair comprising 90% of white hairs.

The greater the value of ΔΕ, the greater the difference in color between the control locks and the dyed locks and the greater color uptake is. Chromaticity in the CIE L*, a*, b* colorimetric system is calculated according to the following equation:

The greater the value of C*, the greater the chromaticity is. The examples that follow serve to illustrate the invention ithout, however, being limiting in nature.

I - Examples of synthesis

Example 1 :

Synthesis of 2-(4-amino-2,3-dimethylphenylamino)-5-[(2- hydroxyethyl)methylamino] [ 1 ,4]benzoquinone (compound 1)

To a solution of 1.04 g (0.005 mol) of 2,3-dimethylbenzene- 1,4-diamine dihydrochloride in 5 ml of water and 3 ml of 20% aqueous ammonia is added a solution of 1.23 g (0.005 mol) of 4- methyl-3,4-dihydro-2H-l,4-benzoxazin-6-ol hydrobromide in 2 ml of water, 1 ml of 20% aqueous ammonia and 10 ml of acetone. 17ml of 6%) aqueous hydrogen peroxide solution are added and the mixture is stirred at room temperature for 4 hours 30 minutes. After filtering off and drying the precipitate formed, 0.49 g of 2-(4-amino-2,3- dimethylphenylamino)-5-[(2-hydroxyethyl)methylamino]- [ 1 ,4]benzoquinone (compound 1) are obtained in the form of a brown powder.

The molecular ion 316 (ES+) is detected by mass spectrometry.

Example 2: Synthesis of 2-[4-(ethylisopropylamino)phenyl- amino)-5-[(2-hydroxyethyl)methylamino][ 1 ,4]benzoquinone

(compound 2)

To a solution of 1.07 g (0.005 mol) of N-(4-aminophenyl)-N- ethyl-N-isopropylamine hydrochloride in 5 ml of water and 2 ml of 20% aqueous ammonia is added a solution of 1.22 g (0.005 mol) of 4- methyl-3,4-dihydro-2H-l,4-benzoxazin-6-ol hydrobromide in 2 ml of water, 1 ml of 20% aqueous ammonia and 15 ml of acetone. 17 ml of aqueous hydrogen peroxide solution are added and the mixture is stirred at room temperature for 4 hours. An oil forms. After 24 hours at 6°C, the oil forms a gum. This gum is taken up in ethyl acetate. After drying and concentrating this organic phase, 0.86 g of 2-[4- (ethylisopropylamino)phenylamino]-5-[(2- hydroxyethyl)methylamino] [ 1 ,4]benzoquinone (compound 2) is obtained in the form of a black powder.

The molecular ion 358 (ES+) is detected by mass spectrometry.

Example 3:

Synthesis of 2-(4-amino-2,3-dimethylphenylamino)-5-[(2- hydroxyethyl)ethylamino] [ 1 ,4]benzoquinone (compound 10)

To a solution of 1.05 g (0.005 mol) of 2,3-dimethylbenzene- 1,4-diamine dihydrochloride in 5 ml of water and 3 ml of 20% aqueous ammonia is added a solution of 1.31 g (0.005 mol) of 4-ethyl-3,4- dihydro-2H- 1 ,4-benzoxazin-6-ol hydrobromide in 3 ml of water, 1 ml of 20% aqueous ammonia and 15 ml of acetone. 17 ml of 6% aqueous hydrogen peroxide solution are added and the mixture is stirred at room temperature for 6 hours 30 minutes. After 12 hours at 6°C, the reaction medium is concentrated and left for a further 12 hours at 6°C. A precipitate forms, which is filtered off. It is purified by chromatography, eluting with dichloromethane/methanol. 0.01 g of 2- (4-amino-2,3-dimethylphenylamino)-5-[(2- hydroxyethyl)ethylamino][l,4]benzoquinone (compound 10) is obtained in the form of a brown powder.

The molecular ion 328 (ES-) is detected by mass spectrometry.

Example 4:

Synthesis of 2-[4-(ethylisopropylamino)phenylamino)-5-[(2- hydroxyethyl)ethylamino] [ 1 ,4]benzoquinone (compound 11)

To a solution of 1.10 g (0.005 mol) of N-(4-aminophenyl)-N- ethyl-N-isopropylamine hydrochloride in 5 ml of water and 3 ml of 20% aqueous ammonia is added a solution of 1.30 g (0.005 mol) of 4-ethyl- 3,4-dihydro-2H-l,4-benzoxazin-6-ol hydrobromide in 3 ml of water, 1 ml of 20% aqueous ammonia and 15 ml of acetone. 17 ml of aqueous hydrogen peroxide solution are added and the mixture is stirred at room temperature for 3 hours 30 minutes. An oil forms. After 12 hours at 6°C, the oil forms a gum. This gum is taken up in ethyl acetate, dried over disodium sulfate and filtered, and the ethyl acetate is evaporated off. The product is purified on a column of silica (eluent: 80/20 ethyl acetate/heptane). The eluent is evaporated off. After 48 hours at 6°C, the product has crystallized, and is left to dry. 0.52 g of 2-[4- (ethylisopropylamino)phenylamino)-5-[(2- hydroxyethyl)ethylamino][l,4]benzoquinone (compound 11) is obtained.

The molecular ion 372 (ES+) is detected by mass spectrometry. Example 5 : Synthesis of 2-(3-chloro-4-hydroxyphenylamino) hydroxyethyl)methylamino] [ 1 ,4]benzoquinone (compound 7)

To a solution of 0.90 g (0.005 mol) of 4-amino-2-chlorophenol hydrochloride in 5 ml of water and 2 ml of 20% aqueous ammonia is added a solution of 1.23 g (0.005 mol) of 4-methyl-3,4-dihydro-2H-l,4- benzoxazin-6-ol hydrobromide in 3 ml of water, 1 ml of 20% aqueous ammonia and 10 ml of acetone. The pH is adjusted to 9.5 with 20% aqueous ammonia. 17 ml of 6%> aqueous hydrogen peroxide solution are added. After 3 hours, the precipitate is filtered off. 0.99 g of 2-(3- chloro-4-hydroxyphenylamino)-5-[(2- hydroxyethyl)methylamino] [ 1 ,4]benzoquinone (compound 7) is obtained in the form of a brown powder.

The molecular ion 323 (ES+) is detected by mass spectrometry.

Example 6: Synthesis of 2-(2-chloro-4-hydroxyphenylamino)- 5-[(2-hydroxyethyl)methylamino] [ 1 ,4]benzoquinone (compound 4)

compoun 4

To a solution of 0.90 g (0.005 mol) of 4-amino-3-chlorophenol hydrochloride in 8 ml of water and 2 ml of 20% aqueous ammonia is added a solution of 1.23 g (0.005 mol) of 4-methyl-3,4-dihydro-2H-l,4- benzoxazin-6-ol hydrobromide in 3 ml of water, 1 ml of 20% aqueous ammonia and 10 ml of acetone. 17 ml of 6% aqueous hydrogen peroxide solution are added and the mixture is stirred at room temperature for 6 hours 30 minutes. After 12 hours at 6°C, the precipitate formed is filtered off and dried. The product is purified on a column of silica (eluent: 100% dichloromethane and then dichloromethane/methanol up to 10% methanol). 0.01 g of 2-(2-chloro-4-hydroxyphenylamino)-5-[(2- hydroxyethyl)methylamino] [ 1 ,4]benzoquinone (compound 4) is obtained.

The molecular ion 323 (ES+) is detected by mass spectrometry. Example 7:

Synthesis of 2-[(4-amino-2,3-dimethylphenyl)amino]-5-[(2 hydroxyethyl)(methyl)amino]benzene- 1 ,4-diol (compound 32)

To a solution of 5 mg of 2-(4-amino-2,3- dimethylphenylamino)-5-[(2- hydroxyethyl)methylamino][l,4]benzoquinone 1 in 2 ml of 0.5M sodium hydroxide are added 15 mg of dithionite in 2 ml of water, and the mixture is stirred until decolorized.

The molecular ion 318 (ES+) is detected by mass spectrometry.

II - Dyeing evaluation of the compounds

The following dye compositions were prepared:

500 mg of illustrated compound

79 g of water,

15 g of ethanol,

5 g of benzyl alcohol, 1 g of the mixture is applied to a lock of 0.25 g of grey hair containing 90% white hairs. After a leave-on time of 30 minutes, the lock is rinsed, washed with a standard shampoo, rinsed again and then dried.

The results are collated in the following table:

III. Comparative examples

The following dyes were compared:

The dye compositions were prepared as follows: 5 mg of dye (compound 3 or compound A) were added to 1 g of dye support constituted of 0,5 % by weight of benzoic acid, 5 % by weight of benzyl alcohol, 15 % by weight of ethanol and 79,5 % by weight of water relative to the total weight of the dye composition.

The pH of the compositions was adjusted to 9.5 with aqueous ammonia containing 20% of NH ₃ .

The mixture is applied to a lock of 0.25 g of grey hair containing 90% white hairs. After a leave-on time o f 30 minutes at ambient temperature, the lock is washed with a standard shampoo .

The evaluation of the coloration is done with a spectrocolorimeter (such as Mino lta CM3600d, illuminant D65 , angle 10° , SCI values) for the L ^* , a ^* , b ^* co lorimetric measurements.

The variation in co loring between the colored locks of natural white hair which is untreated (control) and after treatment or co loration defined by ΔΕ is calculated according to equation (i) as previously mentioned.

Results

According to these results, the dye of the present invention (compound 3) leads to a more intense and chromatic co loration than the comparative dye (compound A) in the same dyeing composition.

Furthermore, the colour uptake is significantly higher with compound 3 than with compound A.