WO2017093558A1

WO2017093558A1 - Novel anionic dyes containing a disulfide heterocyclic unit, dyecomposition comprising them and process for dyeing human keratin materials using these dyes

Info

Publication number: WO2017093558A1
Application number: PCT/EP2016/079734
Authority: WO
Inventors: Aziz Fadli; Zhibo LIU
Original assignee: L'oreal
Priority date: 2015-12-03
Filing date: 2016-12-05
Publication date: 2017-06-08
Also published as: FR3044661A1; FR3044661B1

Abstract

The invention relates to the dyeing of keratin materials using anionic direct dyes containing a disulfide heterocyclic group. The invention relates to a dye composition comprising a fluorescent dye containing a disulfide heterocyclic group, and to a process for dyeing keratin materials such as the hair, using said composition. Similarly, the invention relates to novel dyes containing a disulfide heterocyclic group and to the uses thereof in dyeing keratin materials. This composition makes it possible to obtain a lightening effect that is particularly fast and visible on dark keratin fibres. In addition, the process for dyeing keratin materials, the composition and the anionic dyes of the invention make it possible to obtain colours on said materials that are strong and chromatic and with good colour build- up.

Description

NOVEL ANIONIC DYES CONTAINING A DISULFIDE HETEROCYCLIC UNIT, DYE COMPOSITION COMPRISING THEM AND PROCESS FOR DYEING HUMAN KERATIN MATERIALS USING THESE DYES The invention relates to the dyeing of keratin materials using anionic dyes containing a disulfide heterocyclic group of formulae (I).

It is known practice to dye keratin fibres, in particular human keratin fibres, by direct dyeing. The process conventionally used in direct dyeing consists in applying to keratin fibres direct dyes, which are coloured and colouring molecules that have affinity for the fibres, leaving them to diffuse and then rinsing the fibres.

The direct dyes that are conventionally used are, for example, dyes of the nitrobenzene type, anthraquinone dyes, nitropyridines and dyes of the azo, xanthene, acridine, azine or triarylmethane type.

The dyeing of keratin fibres using these standard direct dyes does not make it possible to notably lighten the keratin fibres.

There is great demand for the lightening of the colour of dark keratin fibres towards lighter shades, optionally while modifying the shade thereof.

Conventionally, to obtain a lighter colouration, a chemical bleaching process is performed. This process consists in treating the keratin fibres, such as the hair, with a strong oxidizing system, generally constituted by hydrogen peroxide optionally combined with persalts, usually in an alkaline medium.

This bleaching system has the drawback of degrading keratin fibres and of impairing their cosmetic properties. Specifically, the fibres have a tendency to become coarse, more difficult to disentangle and more brittle. Finally, the lightening or bleaching of keratin fibres with oxidizing agents is incompatible with treatments for changing the shape of said fibres, particularly in relaxing treatments.

Another lightening technique consists in applying to dark hair fluorescent direct dyes. This technique, described in particular in documents WO 03/028 685 and WO 2004/091 473, makes it possible to respect the quality of the keratin fibre during the treatment. However, these fluorescent direct dyes do not have sufficient fastness with respect to external agents.

In order to improve the persistence, it is known practice to use fluorescent- chromophore dyes that are linked together via a "spacer" or "linker" which contains a disulfide function: see, for example, WO 2005/097 051 , EP 1 647 580, WO 2006/134 043, WO 2006/136 617, WO 2007/1 10 533, WO 2007/1 10 534, WO 2007/1 10 535, WO 2007/1 10 537, WO 2007/1 10 542. Nevertheless, in order for the fixing of these disulfide dyes to the surface of keratin fibres to function, treatment with a reducing agent is generally simultaneously necessary, before or after applying the disulfide dyes. However, the use of reducing agents in appreciable amount may have the drawback of giving off an unpleasant odour during the treatment of the keratin fibres, and as such there is a real need to reduce the content of reducing agent. Furthermore, it is generally necessary to perform an additional oxidative treatment using a chemical oxidizing agent in order to fix the dyes to the keratin fibres and thus to improve the colouration fastness.

Moreover, carboxylic dyes comprising a disulfide heterocycle (A) and(B) (see formulae hereinafter) have been used and evaluated respectively as SERS (Surface Enhanced Raman Scattering) for detecting specific DNA sequences (Tetrahedron, 68(4), 1230-1240 (2012)) and as SAMs (Self Assembled Monolayers) on gold. These compounds have not been used for cosmetic purposes.

The aim of the present invention is to provide novel systems for dyeing and/or lightening keratin materials, in particular human keratin fibres, such as the hair, which are powerful and long-lasting.

Particularly, one aim of the invention is to provide direct dyeing systems for obtaining colours and/or lightening effects which are fast with respect to successive washing, which do not degrade the keratin materials and which do not impair their cosmetic properties. It is also sought to obtain a good colour build-up after treatment of the keratin materials.

Another aim of the invention is to dye keratin materials in a manner that is chromatic, strong and/or persistent with respect to external attacking factors. The invention is also directed towards providing compounds for dyeing keratin fibres such as the hair with little colouration selectivity between the root and the end, whether it is performed on natural or permanent-waved fibres.

These aims are achieved with the present invention, a subject of which is a process for dyeing and/or lightening keratin materials, particularly dark keratin fibres, in which a cosmetic composition comprising one or more anionic direct dyes containing a disulfide heterocyclic group of formula (I) below is applied to said materials:

A- (X)p - Csa, - (X')p. - Het (I)

the organic or mineral acid salts, optical isomers and geometrical isomers thereof, and the solvates such as hydrates;

in which formula (I): > A represents a radical containing at least one anionic chromophore;

> Het represents a 4- to 10-membered disulfide monocyclic heterocyclic radical;

> X and X' , which may be identical or different, represent:

o a linear or branched, saturated or unsaturated Ci-Ci₆ hydrocarbon-based chain, optionally interrupted and/or optionally terminated at one or two of its ends with one or more divalent groups or combinations thereof chosen from: - -N(R)-; -0-; -S-; -C(O)-; -S(0)₂- with R, which may be identical or different, being chosen from a hydrogen atom and a Ci-C₄ alkyl or d-C₄ hydroxyalkyl radical;

- an aromatic or non-aromatic, saturated or unsaturated, fused or non-fused

(hetero)cyclic radical optionally comprising one or more identical or different heteroatoms, optionally substituted;

o a divalent group or the combination chosen from: -N(R)-; -0-; -S-; -C(O)-; - S(0)₂- with R as defined previously;

preferentially, the divalent group(s) or combinations thereof are chosen from -0-;

-N(R)-; -C(O)- with R chosen from a hydrogen atom and a C C₄ alkyl radical;

> p and p', which may be identical or different, represent an integer equal to 0 or 1 ; and

> Csat represents a linear or branched, saturated or unsaturated, optionally substituted Ci-Ci₆ hydrocarbon-based chain.

Another subject of the invention is a dye composition comprising, in a suitable cosmetic medium, at least one anionic direct dye containing a disulfide heterocyclic group of formula (I) as defined previously.

Another subject of the invention relates to the anionic direct dyes containing a disulfide heterocyclic group of formula (I) as defined previously, it being understood that the compound of formula (I) cannot represent the carboxylate forms of the compounds (A) or (B):

The process of the invention makes it possible to obtain a visible colouration of keratin materials, even dark keratin materials, in particular human keratin fibres, in particular the hair, without damaging said material, and that is persistent with respect to shampooing, common attacking factors (sunlight or perspiration), and other hair treatments, even in the absence of a reducing agent. The process of the invention also makes it possible to obtain a lightening of keratin materials such as keratin fibres, particularly dark keratin fibres and more particularly dark hair. In addition, the dyes, the composition and the process of the invention make it possible to improve the colour of keratin materials, in particular in terms of chromaticity, intensity and/or build-up of the colour.

The dyes of the invention are moreover stable with respect to oxidizing agents, and show satisfactory solubility in cosmetic dyeing media. These dyes extend the colour range to yellows and oranges. The dyes of formula (I) colour the keratin materials, after application to keratin fibres, in a manner that is chromatic and persistent with respect to external attacking factors with low colouration selectivity between the root and the end, and on various types of fibres.

In addition, this makes it possible to envisage using dye supports comprising as ingredient anionic compounds such as anionic surfactants, and anionic polymers, without impairing the colour properties of direct dyes.

For the purposes of the invention, the term "dark keratin material" is a material that has a numerical luminescence L^* in the CIE system L^*a^*b^*, of less than or equal to 45 and preferably less than or equal to 40, given that, moreover, L^* = 0 is equivalent to black and L^* = 100 is equivalent to white.

For the purposes of the invention, the expression "naturally or artificially dark hair" is intended to mean hair of which the tone depth is less than or equal to 6 (dark blond) and preferably less than or equal to 4 (chestnut-brown).

The lightening of the hair is evaluated by the "tone depth" variation before and after application of the compound of formula (I). The notion of "tone" is based on the classification of natural shades, one tone separating each shade from the shade immediately following or preceding it. This definition and the classification of natural shades are well known to hairstyling professionals and are published in the book "Sciences des traitements capillaires [Hair treatment sciences]" by Charles Zviak, 1988, published by Masson, pp. 215 and 278.

The tone depths range from 1 (black) to 10 (very light blond), one unit corresponding to one tone; the higher the figure, the lighter the shade.

For the purposes of the invention, the term "bleached hair" is intended to mean hair of which the tone depth is greater than 4 (chestnut-brown) and preferably greater than 6 (dark blond).

One means for measuring the lightening effect given to the hair after application of the fluorescent dyes of the invention is to use the phenomenon of reflectance of the hair.

Preferably, the composition should, after application to dark hair, lead to the results below.

- Interest is focused on the reflectance performance levels of the hair when it is irradiated with visible light in the wavelength range from 400 to 700 nanometres.

- The curves of reflectance as a function of the wavelength, for hair treated with the composition of the invention and for untreated hair, are then compared.

- The curve corresponding to the treated hair should show a reflectance in the wavelength range from 500 to 700 nanometres higher than the curve corresponding to the untreated hair.

- This means that, in the wavelength range from 500 to 700 nanometres, there is at least one region in which the reflectance curve corresponding to the treated hair is higher than the reflectance curve corresponding to the untreated hair. The term "higher" is intended to mean a difference in reflectance of at least 0.05% and preferably of at least 0.1 %. This does not prevent there from possibly being in the wavelength range from 540 to 700 nanometres at least one region in which the reflectance curve corresponding to the treated hair is superposable, or lower than the reflectance curve corresponding to the untreated hair.

Preferably, the wavelength at which the difference is maximal between the reflectance curve for the treated hair and that for the untreated hair is in the wavelength range from 500 to 650 nanometres and preferably in the wavelength range from 550 to 620 nanometres.

For the purposes of the present invention and unless otherwise indicated: the "aryl" or "heteroaryl" radicals or the aryl or heteroaryl part of a radical may be substituted with at least one substituent borne by a carbon atom, chosen from:

• a Ci-C₈ alkyl radical optionally substituted with one or more radicals chosen from the radicals hydroxyl, CrC₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, acylamino, amino substituted with two identical or different d-C₄ alkyl radicals which optionally bear at least one hydroxyl group or it being possible for the two radicals to form, with the nitrogen atom to which they are attached, a saturated or unsaturated and optionally substituted 5- to 7-membered and preferably 5- or 6-membered heterocycle optionally comprising another nitrogen or non- nitrogen heteroatom;

• a halogen atom, such as chlorine, fluorine or bromine;

• a hydroxyl group;

• a C1-C2 alkoxy radical;

• a C₂-C₄ (poly)hydroxyalkoxy radical;

• an amino radical;

• a 5- or 6-membered heterocycloalkyl radical;

• an optionally cationic 5- or 6-membered heteroaryl radical, preferentially imidazolium, optionally substituted with a (CrC₄)alkyl radical, preferentially methyl;

• an amino radical substituted with one or two identical or different Ci-C₆ alkyl radicals optionally bearing at least:

i) a hydroxyl group,

ii) an amino group optionally substituted with one or two optionally substituted C1-C3 alkyl radicals, said alkyl radicals possibly forming with the nitrogen atom to which they are attached a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle, optionally comprising at least one other nitrogen or non-nitrogen heteroatom,

• an acylamino radical (-N(R)-C(0)R') in which the radical R is a hydrogen atom or a CrC₄ alkyl radical optionally bearing at least one hydroxyl group and the radical R' is a Ci-C₂ alkyl radical;

• a carbamoyl radical ((R)₂N-C(0)-) in which the radicals R, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group;

• a carboxylic acid or ester radical, (-O-C(O)R') or (-C(O)OR'), in which the radical R' is a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group, and the radical R' is a Ci-C₂ alkyl radical;

• the carboxylic radical possibly being in acid or salified form (preferably with an alkali metal or a substituted or unsubstituted ammonium);

• an alkylsulfonylamino radical (R'S(0)₂-NR-) in which the radical R represents a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the radical R' represents a C1-C4 alkyl radical, or a phenyl radical;

• an aminosulfonyl ((R)₂N-S(0)₂-) radical in which the R radicals, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group;

• a cyano group (CN);

• a polyhaloalkyl group, preferentially trifluoromethyl (CF₃); the cyclic or heterocyclic part of a non-aromatic radical may be substituted with at least one substituent borne by a carbon atom, chosen from the groups:

• hydroxyl;

• C1-C4 alkoxy or C₂-C₄ (poly)hydroxyalkoxy;

• alkylcarbonylamino ((RC(O)-NR'-) in which the radical R' is a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group, and the radical R is a C C₂ alkyl radical or an amino radical substituted with two identical or different C1-C4 alkyl groups optionally bearing at least one hydroxyl group, said alkyl radicals possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle optionally comprising at least one other nitrogen or non-nitrogen heteroatom;

• alkylcarbonyloxy ((RC(O)-O-) in which the radical R is a C1-C4 alkyl radical or an amino radical substituted with two identical or different C1-C4 alkyl groups optionally bearing at least one hydroxyl group, said alkyl radicals possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle, optionally comprising at least one other nitrogen or non-nitrogen heteroatom;

• alkoxycarbonyl ((RO-C(O)-) in which the radical R is a Ci-C₄ alkyl radical or an amino radical substituted with two identical or different d-C₄ alkyl groups optionally bearing at least one hydroxyl group, said alkyl radicals possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle, optionally comprising at least one other nitrogen or non-nitrogen heteroatom; a cyclic or heterocyclic radical, or a non-aromatic part of an aryl or heteroaryl radical, may also be substituted with one or more oxo groups; a hydrocarbon-based chain is unsaturated when it comprises one or more double bonds and/or one or more triple bonds; an "aryl" radical represents a fused or non-fused monocyclic or polycyclic group containing from 6 to 22 carbon atoms, and in which at least one ring is aromatic; preferentially, the aryl radical is a phenyl, biphenyl, naphthyl, indenyl, anthracenyl or tetrahydronaphthyl; a "heteroaryl radical" represents a fused or non-fused, optionally cationic, 5- to 22-membered monocyclic or polycyclic group, comprising from 1 to 6 heteroatoms chosen from nitrogen, oxygen, sulfur and selenium atoms, and at least one ring of which is aromatic; preferentially, a heteroaryl radical is chosen from acridinyl, benzimidazolyl, benzobistriazolyl, benzopyrazolyl, benzopyridazinyl, benzoquinolyl, benzothiazolyl, benzotriazolyl, benzoxazolyl, pyridyl, tetrazolyl, dihydrothiazolyl, imidazopyridyl, imidazolyl, indolyl, isoquinolyl, naphthoimidazolyl, naphthooxazolyl, naphthopyrazolyl, oxadiazolyl, oxazolyl, oxazolopyridyl, phenazinyl, phenoxazolyl, pyrazinyl, pyrazolyl, pyrilyl, pyrazoyltriazyl, pyridyl, pyridinoimidazolyl, pyrrolyl, quinolyl, tetrazolyl, thiadiazolyl, thiazolyl, thiazolopyridyl, thiazoylimidazolyl, thiopyrylyl, triazolyl and xanthylyl;

- a "cyclic radical" is a non-aromatic, monocyclic or polycyclic, fused or non-fused cycloalkyi radical, containing from 5 to 22 carbon atoms, which may comprise one or more unsaturations; a "heterocyclic radical" is a non-aromatic, monocyclic or polycyclic, fused or non- fused 5- to 22-membered radical, comprising from 1 to 6 heteroatoms chosen from nitrogen, oxygen, sulfur and selenium atoms, morpholinyl, thiomorpholinyl, piperidyl, piperazinyl, pyrrolidinyl, tetrahydrofuranyl, tetrahydrothiophenyl, azepanyl, thioazepanyl; preferentially pyrrolidinyl and morpholino; a "disulfide heterocyclic radical" is a heterocyclic radical comprising in its ring an S-S disulfide sequence between two carbon atoms, directly, said heterocycle possibly being substituted; an "alkyl radical" is a linear or branched Ci-Ci₆ and preferably Ci-C₈ hydrocarbon- based radical; the expression "optionally substituted" attributed to the alkyl radical implies that said alkyl radical may be substituted with one or more radicals chosen from the following radicals: i) hydroxyl, ii) CrC₄ alkoxy, iii) acylamino, iv) amino optionally substituted with one or two identical or different d-C₄ alkyl radicals, said alkyl radicals possibly forming, with the nitrogen atom that bears them, a 5- to 7- membered heterocycle, optionally comprising another nitrogen or non-nitrogen heteroatom, v) C(0)OM with M representing a hydrogen atom or a cationic counterion such as an alkali metal or alkaline-earth metal or ammonium;

- an ""alkoxy radical" is an alkyloxy radical for which the alkyl radical is a linear or branched Ci-Ci₆ and preferentially Ci-C₈ hydrocarbon-based radical; when the alkoxy group is optionally substituted, this implies that the alkyl group is optionally substituted as defined above.

The compounds of formula (I) according to the invention may be anionic, cationic or neutral;

- the chromophore A is anionic; either it comprises one or more counterions or mixture of counterions in order to ensure electroneutrality, or else one or more group(s) in the compound make(s) it possible to ensure electroneutrality. For example, if the rest of the compound is anionic via -O^", -C(0)0^", S(0)₂-0^" or -P(0)(OH)₂-0^" groups, either there are in the molecule one or more— N⁺(R)₂— , or phosphonium groups, in order to ensure electroneutrality, or it is in the form -

O^", M⁺, -C(0)0^", M⁺, or S(0)₂-0^" M⁺, with M⁺ representing a cationic counterion, preferentially chosen from alkali metal or alkaline-earth metal cations such as Na, Mg, K and Ca, and organic cations such as ammonium NH₄ ⁺ or (di/tri)(C₁- C₆)alkylammonium;

- an "organic or mineral acid salt" is more particularly chosen from a salt derived from i) hydrochloric acid HCI, ii) hydrobromic acid HBr, iii) sulfuric acid H₂S0₄, iv) alkylsulfonic acids: Alk-S(0)₂OH such as methylsulfonic acid and ethylsulfonic acid; v) arylsulfonic acids: Ar-S(0)₂OH such as benzenesulfonic acid and toluenesulfonic acid; vi) citric acid; vii) succinic acid; viii) tartaric acid; ix) lactic acid; x) alkoxysulfinic acids: Alk-0-S(0)OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H₃P0₄; xiii) acetic acid CH₃COOH; xiv) triflic acid CF₃S0₃H; and xv) tetrafluoroboric acid HBF₄.

Furthermore, unless otherwise indicated, the limits delimiting the extent of a range of values are included in this range of values. According to the present invention, the term "anionic chromophore" is intended to mean a radical derived from an anionic direct dye. An anionic direct dye is a compound which is capable of absorbing in the visible range and optionally in the ultraviolet range, i.e. at a wavelength between 250 and 800 nm.

The chromophore may also be fluorescent, i.e. it is capable of absorbing in the visible range and optionally in the ultraviolet range and it is also capable of re-emitting the absorbed light in the visible range at an emission wavelength greater than the absorption wavelength, i.e. e_m between 400 and 800 nm. Preferably, the fluorescent chromophore is derived from a fluorescent dye capable of absorbing in the visible range between 400 and 800 nm and of re-emitting in the visible range e_m between 400 and 800 nm. More preferentially, the fluorescent chromophore is derived from a dye capable of absorbing at a between 420 nm and 550 nm and of re-emitting in the visible range at a e_m between 470 and 600 nm.

/. Dyes of formulae (I)

The dye(s) of formula (I) are anionic, i.e. the radical A of formula (I) contains one or more anionic chromophores, which may be identical or different, it being understood that, when A comprises several chromophores, it comprises more anionic chromophores than cationic chromophores. Preferably, all the chromophores of A are anionic. /.1. Anionic chromophore A

The dyes of the invention of formula (I) are anionic direct dyes. The anionic chromophore(s) of the invention is (are) derived from anionic direct dyes called "acid dyes" for their affinity with alkaline substances (see, for example, "Industrial Dyes, Chemistry, Properties, Application", Klaus Hunger published by Wiley-VCH Verlag GmbH & CoKGaA, Weinheim 2003). Anionic or acid dyes are known in the literature (see, for example, Ullman's Encyclopedia of Industrial Chemistry, Azo Dyes, 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a03 245, point 3.2; ibid, Textile Auxiliaries, 2002 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a26 227 and Ashford's Dictionary of Industrial Chemicals, Second Edition, p. 14-p. 39, 2001 ).

The term "anionic direct dyes" is intended to mean any direct dye comprising in its structure at least one sulfonate S0₃ ^" group and/or at least one carboxylate group C(0)0^" and optionally one or more supplementary anionic groups G^" with G^", which may be identical or different, representing an anionic group chosen from alkoxide O^", thiolate S^", carboxylate and thiocarboxylate: C(Y)Y'^", with Y and Y', which may be identical or different, representing an oxygen or sulfur atom; preferably, G^" represents a carboxylate, i.e. Y and Y represent an oxygen atom.

More particularly, A represents a chromophore A1 :

with:

^■ representing the anionic part of the chromophore derived from an anionic direct dye or acid dye comprising in its structure at least one sulfonate group and/or at least one carboxylate group and comprising m anionic charge(s):

^■ m and n, which may be identical or different, represent an integer between 1 and 10 inclusive;

^■ Q⁺, which may be identical or different, represents a cosmetically acceptable, organic or mineral, cationic counterion preferably chosen from alkali metal or alkaline-earth metal cations such as Na⁺ or K⁺, or ammonium, (di)(tri)(Ci-

C₆)alkylammonium, or cationic heteroaryl such as pyridinium or imidazolium; it being understood that:

- when n is greater than or equal to 2, then Q may be identical to or different from one another; - m and n are such that the electroneutrality of the dyes of the invention (I) is ensured.

Preferentially, -Col^m comprises in its structure:

o at least one sulfonate group and at least one (hetero)aryl group, it being understood that at least one sulfonate group is directly connected to a

(hetero)aryl group, preferentially aryl such as phenyl or benzo; and

o optionally one or more anionic groups G^" as defined previously.

According to another preferred embodiment of the invention, Col^m comprises in its structure:

o at least one carboxylate group and at least one (hetero)aryl group, it being understood that at least one carboxylate group is directly connected to a (hetero)aryl group, preferentially aryl such as phenyl or benzo; and

o optionally one or more anionic groups G^" as defined previously.

According to yet another preferred embodiment of the invention, -Col'^"'™ comprises in its structure:

o at least one carboxylate group and at least one (hetero)aryl group, it being understood that at least one sulfonate or carboxylate group is directly connected to a (hetero)aryl group, preferentially aryl such as phenyl or benzo; and

o optionally one or more anionic groups G^" as defined previously.

o at least one carboxylate group, at least one sulfonate group and at least one (hetero)aryl group, it being understood that at least one sulfonate or carboxylate group is directly connected to a (hetero)aryl group, preferentially aryl such as phenyl or benzo; and

o optionally one or more anionic groups G^" as defined previously.

According to one particular embodiment of the invention, the dyes of formula (I) are such that A represents A1 with m equal to n. An advantageous variant of the invention concerns the dyes of formula (I) for which m and n are equal to 1 , 2 or 3.

According to one particular embodiment, the preferred dye(s) of formula (I) of the invention are chosen from those for which A is derived from acid nitro direct dyes, acid azo dyes such as diaryls or pyrrazolones, acid azine dyes, acid triarylmethane dyes, acid indoamine dyes, acid xanthene dyes, acid anthraquinone dyes, acid quinoline dyes, indigoid dyes and acid natural dyes; each of these dyes having at least one sulfonate or carboxylate group with a cationic counterion as defined previously, more particularly between 1 and 5 sulfonate or carboxylate groups, preferably between 1 and 3 sulfonate or carboxylate groups.

Preferentially, the preferred dye(s) of formula (I) of the invention are chosen from those for which A is derived from direct dyes chosen from diaryl anionic azo dyes; pyrrazolone anionic azo dyes; anthraquinone anionic dyes; anionic nitro dyes; anionic triarylmethane dyes; anionic indigoid or indole derived dyes; and anionic quinoline dyes; each of these dyes having at least one sulfonate or carboxylate group with a cationic counterion as previously defined, more particularly between 1 and 5 sulfonate or carboxylate groups, preferably between 1 and 3 sulfonate or carboxylate groups; more preferentially, A is derived from diaryl anionic azo dyes.

By way of examples of dyes having the formula of diaryl anionic azo dyes, mention may be made of: Acid Red 1 , Acid Red 4, Acid Red 13, Acid Red 14, Acid Red 18, Acid Red 27, Acid Red 32, Acid Red 33, Acid Red 35, Acid Red 37, Acid Red 40, Acid Red 41 , Acid Red 42, Acid Red 44, Acid Red 68, Acid Red 73, Acid Red 135, Acid Red 138, Acid Red 184, Food Red 1 , Food Red 13, Acid Orange 6, Acid Orange 7, Acid Orange 10, Acid Orange 19, Acid Orange 20, Acid Orange 24, Acid Yellow 9, Acid Yellow 36, Acid Yellow 199, Food Yellow 3; Acid Violet 7, Acid Violet 14, Acid Blue 1 13, Acid Blue 1 17, Acid Black 1 , Acid Brown 4, Acid Brown 20, Acid Black 26, Acid Black 52, Food Black 1 , Food Black 2; Acid Red 1 1 1 , Acid Red 134 and Acid yellow 38.

According to one particular embodiment, A is an anionic fluorescent chromophore derived from anionic direct fluorescent dyes. Mention may be made of the following direct dyes: anionic triarylmethanes; anionic xanthene dyes and anionic quinoline dyes; each of these dyes having at least one sulfonate or carboxylate group with a cationic counterion as previously defined. Preferably, A is derived from a fluorescent dye which absorbs in the yellow, orange and red range.

As indicated previously, in formula (I), C_sat represents a linear or branched, optionally substituted, divalent Ci-Ci₆ hydrocarbon-based chain. Substituents that may be mentioned include amino groups, (Ci-C₄)alkylamino groups, (CrC₄)dialkyl amino groups, or the group R^a-Z^a-C(Z^b)- (in which Z^a, Z^b, which may be identical or different, represent an oxygen or sulfur atom or a group NR^a', and R^a represents an alkali metal, a hydrogen atom or a C C₄ alkyl group and R^a' represents a hydrogen atom or a C C₄ alkyl group) preferably present on the carbon in the beta or gamma position relative to the atoms of the disulfide sequence -S-S- of the heterocycle Het. In particular, in the case of formulae (I), C_sat represents a linear or branched, preferably linear, saturated or unsaturated, preferably saturated, divalent hydrocarbon- based chain comprising from 1 to 14 carbon atoms, preferably between 2 and 10, more preferentially between 3 and 6 carbon atoms, such as 4 carbon atoms.

1.3. Xand X':

In accordance with one particular embodiment of the invention, in the abovementioned formula (I), when p or p' is equal to 1 , X and X', which may be identical or different, represent the following sequence:

-(T)_t-(Z)_z-(T')_t- said sequence being linked in formulae (I), as follows:

- C_sa,-(T')_t.-(Z)_z-(T)_t-(A or Het);

in which sequence:

> T and T', which may be identical or different, represent one or more radicals or combinations thereof chosen from: -S(0)₂-; -0-; -S-; -N(R)-; -C(O)-; with R representing a hydrogen atom, a Ci-C₄ alkyl radical, C C₄ hydroxyalkyl radical or an aryl(Ci-C₄)alkyl radical; and a cationic or non-cationic, preferentially monocyclic heterocycloalkyl or heteroaryl radical, preferentially containing two heteroatoms (more preferentially two nitrogen atoms) and preferentially being 5- to 7-membered, more preferentially piperazinyl or piperidinyl;

preferentially, T and T represent one or more radicals or combinations thereof chosen from -0-, -N(R)-, -C(O)-, with R chosen from a hydrogen atom and a Ci-C₄ alkyl radical;

> the indices t and t', which may be identical or different, are 0 or 1 ;

> Z represents:

-(CRiR₂)_m- with m being an integer between 1 and 8 and Ri and R₂, which may be identical or different, representing a hydrogen atom or a C C₄ alkyl, C1-C12 alkoxy, hydroxyl, cyano, carboxy, amino, C C₄ alkylamino or C C₄ dialkylamino group, said alkyl radicals possibly forming, with the nitrogen atom which bears them, a 5- to 7-membered heterocycle, optionally comprising another heteroatom identical to or different from nitrogen; -(CH₂CH₂0)_q- or -(OCH₂CH₂)_q- in which q is an integer between 1 and 15, or an aryl, alkylaryl or arylalkyl radical in which the alkyl radical is C C₄ and the aryl radical is preferably C₆, being optionally substituted with at least one group SO₃M with M representing a hydrogen atom, an alkali metal or an ammonium ammonium group substituted with one or more identical or different, linear or branched Ci-Ci₈ alkyl radicals optionally bearing at least one hydroxyl;

z is 0 or 1 .

Moreover, according to one particular embodiment of the invention, Z represents:

with q as defined previously and r representing an integer between 0 and 4 inclusive, M representing an anionic counterion as defined previously.

1.4. Het:

As indicated previously, in formula (I), Het represents a 4- to 10-membered disulfide monocyclic heterocyclic radical.

According to one particular embodiment, Het is of formula (II) linked to the rest of the molecule by one of the substituents R₅, R6, R7, Rs, Rsi or R₁₀, or else said radical is linked to the rest of the molecule directly by one of the carbon atoms of the heterocycle radical in the alpha, beta position with respect to the disulfide sequence or, when q is 2 or 3, in the gamma position, in which case one of the substituents R₅, R₆, R₇, R₈, Rg or R₁₀ is absent:

in which formula (II):

^■ R₅, R₆, Rg and R1₀, which may be identical or different, represent a hydrogen atom, or a group chosen from: i) (CrC₈)alkyl, iii) hydroxyl, iv) (di)(Ci- C₈)(alkyl)amino, v) (Ci-C₈)alkoxy, particularly R₅, R₆, Rg and R1₀ represent a hydrogen atom or a (CrC₄)alkyl group such as methyl, preferably R₅, R6, Rg and R1₀ represent a hydrogen atom;

^■ R₇ and R₈, which may be identical or different, represent a hydrogen atom, or a group chosen from: i) (Ci-C₈)alkyl, iii) hydroxyl, iv) (di)(Ci- C₈)(alkyl)amino, v) (Ci-C₈)alkoxy; particularly R₇ and R₈, are chosen from a hydrogen atom and a (CrC₄)alkyl group such as methyl, preferably R₇ and R₈ represent a hydrogen atom;

^■ or else two radicals borne by the same carbon atom R₅ and R₆, R7 and R₈, and/or R₉ and R10 form, together with the carbon atom which bears them, a carbonyl group;

^■ q represents an integer between 1 and 3 inclusive, particularly between 1 and 2;

it being understood that when q is 2 or 3, then the R₇ and R₈ groups may be identical to or different from one another;

preferentially, q is 1 ; and more particularly all the substituents R₅ to R10 represent a hydrogen atom.

1.4. Dyes of formula (I) or (Π: Another subject of the invention relates to the anionic direct dyes containing a disulfide heterocyclic group of formula (I) as defined, it being understood that the compounds of formula (I) cannot represent the carboxylate forms of the compounds (A) or (B):

(B)

According to one particular embodiment of the invention, the anionic direct dyes of the invention are chosen from the dyes of formulae (I'a) to (I'g) below:

(i'g)

and also the organic or mineral acid salts, optical isomers, geometrical isomers and tautomers thereof and the solvates such as hydrates;

in which formulae (I'a) to (I'g):

• A is as defined previously, in particular A is derived from acid nitro direct dyes, acid azo dyes such as diaryls or pyrrazolones, acid azine dyes, acid triarylmethane dyes, acid indoamine dyes, acid xanthene dyes, acid anthraquinone dyes, acid quinoline dyes, acid indigoid dyes and acid natural dyes; each of these dyes having at least one sulfonate or carboxylate group with a cationic counterion as defined previously, more particularly between 1 and 5 sulfonate or carboxylate groups, preferably between 1 and 3 sulfonate or carboxylate groups;

more preferentially, A is derived from diaryl anionic azo dyes comprising from 1 to 5 sulfonate or carboxylate groups, preferably between 1 and 3 sulfonate groups;

• X and X' are as defined previously,

in particular, X and X' represent a divalent group or the combination chosen from: -N(R)-, -0-, -S-, -C(O)- and -S(0)₂- with R as defined previously;

preferentially, the divalent group(s) or combinations thereof are chosen from - 0-, -N(R)- and -C(O)- with R chosen from a hydrogen atom and a CrC₄ alkyl radical; more preferentially, X and X' represent an amide divalent group -N(R)-C(0)- or -C(0)-N(R)- with R representing a hydrogen atom or a Ci-C₄ alkyl radical;

• p and p', which may be identical or different, represent an integer equal to 0 or 1 ; preferably, p is 1 and p' is 0; and

• Csat is as defined previously, and preferably represents an unsubstituted, linear or branched C1-C1₀, more preferentially C₂-C₈, better still C₃-C₅, such as C₄, alkylene chain;

• R₅, R₆, Rg and Rio, as defined previously, particularly represent a hydrogen atom or a (Ci-C₄)alkyl group such as methyl, preferably R₅, R6, R9 and R1₀ represent a hydrogen atom;

• R₇ and R₈, as defined previously, particularly represent a hydrogen atom or a (Ci-C₄)alkyl group such as methyl, preferably R₇ and R₈ represent a hydrogen atom;

preferentially, all the substituents R₅ to R1₀ represent a hydrogen atom.

Preferentially, the compounds of formula (I) of the invention are chosen from the compounds (I'a) and (I'b), more preferentially (I'a).

According to one particular embodiment, the anionic dyes of formula (I) of the invention are chosen from the following compounds (l"a) and (l"b):

(l"a)

(l"b)

in which formula (I):

• X, X' , p, p', Csat, R5, R6, R7, Re, R9 and R10 are as defined previously for the compounds of formulae (I'a) to (I'g), q is 1 or 2, it being understood that when q is 2 then the R₇ and R₈ groups may be identical to or different from one another, preferably q is 1 ; preferably, p is 1 and p' is 0, R₅ to R1₀ represent a hydrogen atom, X represents an amide divalent group -N(R)-C(0)- or -C(0)-N(R)- with R representing a hydrogen atom or a C1-C4 alkyl radical; and C_sat represents an unsubstituted linear or branched, more preferentially linear, C1-C1₀ alkylene chain;

• Ri and R₂, which may be identical or different, represent a group chosen from: i) hydroxyl, ii) thiol, iii) nitro, iv) optionally substituted (CrC₆)alkyl, in particular (d- C₄)alkyl such as methyl or ethyl, v) (CrC₆)alkoxy, in particular (CrC₄)alkoxy such as ethoxy or methoxy, vi) (CrC₆)alkylthio, vii) halogen and viii) amino - NR_aRb with R_a and R_b, which may be identical or different, representing:

o a hydrogen atom,

o a (CrC₆)alkyl group, particularly (CrC₄)alkyl group such as methyl or ethyl, said alkyl group being optionally substituted with one or more hydroxyl groups, or else

o R_a and R_b form, with the nitrogen atom which bears them, a 5- to 8- membered, preferably 5- or 6-membered, saturated or unsaturated heterocycle,

said heterocycle possibly also:

a) containing one or more heteroatoms or groups chosen from oxygen, sulfur and N(R_C), with R_c representing a hydrogen atom or a (CrC₄)alkyl group optionally substituted with one or more hydroxyl groups, such as methyl, ethyl or hydroxyethyl, and/or

b) being substituted with one or more groups, which may be identical or different, chosen from hydroxyl, (C1-C4) alkyl optionally substituted with one or more hydroxyl groups, (CrC₄)alkyloxy such as ethoxy or methoxy, (di)(Ci-C₄)(alkyl)amino, (di)hydroxy(Ci-C₄)alkylamino;

Z and Z', which may be identical or different, represent a carboxylate group -C(0)0^", M⁺ or sulfonate group -S(0)₂-0^" M⁺, with M⁺ representing a cosmetically acceptable cationic counterion, preferentially chosen from alkali metal or alkaline-earth metal cations such as Na, Mg, K and Ca, and organic cations such as ammonium NH₄ ⁺, (di/tri)(Ci-C₆)alkylammonium, a cationic heteroaryl such as pyridinium; preferentially, Z and Z' represent an -S(0)₂-0^" M⁺ group;

t and t', which may be identical or different, represent an integer between 0 and 5 inclusive, it being understood that z+z' is an integer greater than or equal to 1 ; in particular z+z' is an integer between 1 and 3 inclusive;

x is an integer between 0 and 5 inclusive;

x' is an integer between 0 and 4 inclusive; · , which may be present or absent, represents a benzo ring; the ring is preferably absent;

it being understood that, when x, x', t and t' are greater than or equal to 2, then respectively Ri are identical to or different from one another, R₂ are identical to or different from one another, Z are identical to or different from one another, and Z' are identical to or different from one another.

Preferentially, the anionic dyes of formula (I) according to the invention are chosen from those of formula (l"b).

According to one particular embodiment of the invention, the dyes are chosen from those of formula (l'"b):

(l"'b)

in which formula (l'"b) X, p, Z', t', q, C_sat, Ri, x, R2 and x' are as defined previously for the compounds of formula (l"b);

preferentially: x represents an integer between 0 and 4 inclusive, particularly between 1 and 3, and preferably is equal to 0 or 1 ;

x' represents an integer between 0 and 3, particularly between 1 and 2, and preferably is equal to 1 ;

X represents an amide divalent group -N(R)-C(0)- or -C(0)-N(R)-, preferably -N(R)-C(0)- with R representing a hydrogen atom or a CrC₄ alkyl radical;

p is 1 ;

t' represents an integer between 1 and 3 inclusive, such as 2;

Ri, which may be identical or different, represents a group chosen from: i) hydroxyl, ii) nitro, iv) (CrC₆)alkyl, in particular (CrC₄)alkyl such as methyl or ethyl, v) (CrC₆)alkoxy, in particular (d-C₄)alkoxy such as ethoxy or methoxy, vi) (CrC₆)alkylthio, in particular (CrC₄)alkylthio such as ethylthio or methylthio, and vii) amino -NR_aR_b with R_a and R_b, which may be identical or different, representing:

o a hydrogen atom,

o a (CrC₆)alkyl group, particularly (CrC₄)alkyl group such as methyl or ethyl, said alkyl group being optionally substituted with one or more hydroxyl groups such as hydroxyethyl,

or else

o R_a and R_b form, with the nitrogen atom which bears them, a 5- or 6- membered saturated heterocycle, said heterocycle possibly also:

a) containing one or more heteroatoms or groups chosen from oxygen, sulfur and N(R_C), with R_c representing a hydrogen atom or a (C C₄)alkyl group optionally substituted with one or more hydroxyl groups, such as methyl, ethyl or hydroxyethyl, and/or

b) being substituted with one or more hydroxyl groups;

R₂, which may be identical or different, represents a group chosen from: i) hydroxyl, ii) thiol, iv) (CrC₆)alkyl, in particular (CrC₄)alkyl such as methyl or ethyl, v) (CrC₆)alkoxy, in particular (CrC₄)alkoxy such as ethoxy or methoxy, vi) (CrC₆)alkylthio, in particular (CrC₄)alkylthio such as ethylthio or methylthio, and vii) amino -NR_aR_b with R_a and R_b, which may be identical or different, representing a hydrogen atom, or a (CrC₆)alkyl group, particularly (CrC₄)alkyl group such as methyl or ethyl; preferably, R₂ represents a hydroxyl or thiol group, more preferentially thiol group;

Z', which may be identical or different, represents an -S(0)₂-0^" M⁺ group with M⁺ representing a cationic counterion, preferentially chosen from alkali metal or alkaline-earth metal cations such as Na, Mg, K and Ca, and organic cations such as ammonium NH₄ ⁺ or (di/tri)(Ci-C₄)alkylammonium;

• C_sat represents a linear or branched, preferably linear, (d-C₈)alkylene group, such as -(CH₂)_m- with m representing an integer between 2 and 8 inclusive, in particular between 3 and 6, such as m is 4;

particularly, Ri is on the phenyl ring in position 2', 4' and/or 6', preferably in position 4'; particularly, R₂ is on the naphthyl ring in position 1 , 4, 5 and/or 8, preferably in position 8;

particularly, the group X is linked to the naphthyl ring in position 1 , 4, 5 and/or 8, preferably in position 1 , it being understood that X cannot be positioned on a position where there is an R₂ group;

in particular, Z' is on the naphthyl ring in position 2, 3, 6 and/or 7, preferably in position 3 and 6; and

in particular, the azo group -N=N- is linked to the naphthyl ring in position 2, 3, 6, and/or 7, preferably in position 2 or 7, more preferentially 7, it being understood that - N=N- cannot be positioned on a position where there is a Z' group.

According to one particular embodiment of the invention, the dyes are chosen from those of formula (l""b):

(l""b)

in which formula (l""b) C_sat, ⁺, R, Ri, x, R₂ and x' are as defined previously;

preferably,

x' is 0, 1 or 2, more particularly x' is 0;

- R represents a hydrogen atom or a (CrC₄)alkyl group; more preferentially, R represents a hydrogen atom; and

R₂ is positioned in position 2 or 5 on the naphthyl ring.

Preferably, the anionic dyes of formula (I) are of formula (l'"b) with x' = 0; x = 0 or 1 ;

R represents a hydrogen atom or a (CrC₄)alkyl group; more preferentially, R

represents a hydrogen atom;

Ri represents a group chosen from i) hydroxyl, ii) nitro, iii) Ci-C₄ alkylthio such as methylthio, iv) CrC₄, more preferentially CrC₂, alkoxy, such as methoxy or ethoxy, v) amino NR_aR_b with:

R_a and R_b, which may be identical or different, representing a hydrogen atom, a C C₄ alkyl group such as methyl or ethyl, or a CrC₄, preferentially CrC₂, hydroxyalkyl group such as hydroxyethyl; or else

- R_a and R_b form, together with the nitrogen atom which bears them, a 5- or 6- membered saturated heterocyde, said heterocyde possibly also:

o comprising one or more heteroatoms or groups chosen from an oxygen atom or -N(R_C)- group, with R_c representing a hydrogen atom or a CrC₄ alkyl group such as methyl, and/or

o being substituted with one or more groups, which may be identical or different, chosen from hydroxyl, CrC₄ alkyl, C1-C4 hydroalkyl, C1-C4 alkoxy, (di)(Ci-C₄)(alkyl)amino and (di)hydroxy(Ci-C₄)alkylamino groups; and

Csat denotes a saturated divalent hydrocarbon-based (or alkylene) chain containing from 2 to 8 carbon atoms, preferably from 3 to 6 carbon atoms.

More particularly, the anionic dyes of formula (I) are of formula (l'"b) with:

- x" = 0; x = 0 or 1 ;

R represents a hydrogen atom; and

Ri represents a group chosen from i) hydroxyl, nitro (N0₂), iii) CrC₄ alkylthio such as methylthio, CrC₄ alkoxy such as methoxy or ethoxy, iv) amino NR_aRb with R_a and R_b independently representing a hydrogen atom, a CrC₄ alkyl group such as methyl or ethyl; a CrC₄, more preferentially CrC₂, hydroxyalkyl group, such as hydroxyethyl, or else R_a and R_b form, with the nitrogen atom which bears them, a 5- or 6-membered saturated heterocyde chosen from pyrrolidine, piperidine and piperazine rings, said heterocyde possibly also being substituted with one or more groups, which may be identical or different, chosen from hydroxyl groups, Ci-C₄ alkyl groups such as methyl, and CrC₄ hydroalkyl groups such as hydroxyethyl; Csat represents a (C₃-C₆)alkylene group such as butylene -(CH₂)₄-.

More preferentially, the anionic dyes of formula (I) are chosen from:

with M⁺ a cationic counterion as defined previously, preferably alkali metal such as Na or K, or ammonium or pyridinium;

compounds 1 to 15 and also the optical isomers, geometrical isomers, tautomers thereof and the solvates such as hydrates thereof.

The compounds (I) may be synthesized via a reaction between a compound (a1 ) and a compound (a1 ). This reaction is illustrated in the scheme below:

with A, X, p, q, C_sat and R₅ to Rio as defined previously; Nu representing a nucleophilic group; <£ representing an electrophilic group; and T_b the bond generated after attack of the nucleophile on the electrophile. These nucleophilic substitution reactions are known to those skilled in the art. Reference may be made, for example, to the book Advanced Organic Chemistry (ISBN 0-471 -60180-2).

By way of example, the covalent bonds T_b that may be generated are listed in Table A below, starting with condensation of electrophiles with nucleophiles:

Table A

Electrophiles ^<£ Nucleophiles Mu Covalent bonds T_b

Activated esters^* Amines Carboxamides

Acyl azides^** Amines Carboxamides

Acyl halides Amines Carboxamides

Acyl halides Alcohols Esters

Acyl cyanides Alcohols Esters

Acyl cyanides Amines Carboxamides

Alkyl halides Amines Alkylamines

Alkyl halides Carboxylic acids Esters

Alkyl halides Thiols Thioesters

Alkyl halides Alcohols Ethers

Sulfonic acids and salts thereof Thiols Thioethers

Sulfonic acids and salts thereof Carboxylic acids Esters

Sulfonic acids and salts thereof Alcohols Ethers

Anhydrides Alcohols Esters

Anhydrides Amines Carboxamides

Aryl halides Thiols Thioethers

Aryl halides Amines Arylamines

Aziridines Thiols Thioethers

Carboxylic acids Amines Carboxamides

Carboxylic acids Alcohols Esters

Carbodiimides Carboxylic acids N-Acylureas or

anhydrides

Diazoalkanes Carboxylic acids Esters

Epoxides Thiols Thioethers

Haloacetamides Thiols Thioethers

Imide esters Amines Amidines

Isocyanates Amines Ureas

Isocyanates Alcohols Urethanes Isothiocyanates Amines Thioureas

Maleimides Thiols Thioethers

Sulfonic esters Amines Alkylamines

Sulfonic esters Thiols Thioethers

Sulfonic esters Carboxylic acids Esters

Sulfonic esters Alcohols Ethers

Sulfonyl halides Amines Sulfonamides

^*the activated esters of general formula -CO-Part with Part representing a leaving group

such as optionally substituted oxysuccinimidyl, oxybenzotriazolyl or aryloxy;

^** the acyl azides may rearrange to give isocyanates.

These reactions are known to those skilled in the art and are described in the literature. Reference may be made to the book Advanced Organic Chemistry (ISBN 0- 471 -60180-2).

One variant to this process is to use a fluorescent chromophore containing an electrophilic acrylate function (-0-C(0)-C=C-) on which is performed an addition reaction that will generate a bond T_b.

In some cases, it is necessary to protect the nucleophilic and electrophilic groups of the reagents that are not intended to react with one another before the condensation reaction. It is then necessary to deprotect said nucleophilic and electrophilic groups. Amine-protecting, hydroxyl-protecting and thiol-protecting groups, for example, are well known to those skilled in the art, including the reaction conditions necessary for the protection and deprotection step. Reference may be made to the book Protecting groups in Organic Chemistry (ISBN 0-471 -05764-9) for the protection and deprotection conditions.

Compounds (a2) are known to those skilled in the art, and their synthesis is described in Comprehensive Heterocyclic Chemistry III, 2008, Chapter 4.1 1 , Pages 893-954 and Comprehensive Heterocyclic Chemistry III, 2008, Chapter 13.10, Pages 299-319. Some compounds are commercially available.

Alternatively, the compounds ( ) may be synthesized via a reaction between a compound (a3) and a compound (a4). This reaction is illustrated in the scheme below:

with A, X, p, q, C_sat, R5 to R₁₀, and T_b as defined previously; 3Vu representing a nucleophilic group; <£ representing an electrophilic group. Alternatively, the compounds (l₂) may be synthesized via a reaction between a compound (a5) and a compound (a6). This reaction is illustrated in the scheme below:

with A, X, p, q, C_sat and R₅ to R₁₀ as defined previously; Nu representing a nucleophilic group; <£ representing an electrophilic group; and T_a the bond generated after attack of the nucleophile on the electrophile. By way of example, the covalent bonds T_a that may be generated are listed in Table B, starting with condensation of electrophiles with nucleophiles:

Table B:

Electrophiles Έ Nucleophiles Mi Covalent bonds T_a

Activated esters^* Amines Carboxamides

Acyl azides^** Amines Carboxamides

Acyl halides Amines Carboxamides

Acyl halides Alcohols Esters

Acyl cyanides Alcohols Esters

Acyl cyanides Amines Carboxamides

Alkyl halides Amines Alkylamines Alkyl halides Carboxylic acids Esters

Alkyl halides Thiols Thioesters

Alkyl halides Alcohols Ethers

Sulfonic acids and salts thereof Thiols Thioethers

Sulfonic acids and salts thereof Carboxylic acids Esters

Sulfonic acids and salts thereof Alcohols Ethers

Anhydrides Alcohols Esters

Anhydrides Amines Carboxamides

Aryl halides Thiols Thioethers

Aryl halides Amines Arylamines

Aziridines Thiols Thioethers

Carboxylic acids Amines Carboxamides

Carboxylic acids Alcohols Esters

Carbodiimides Carboxylic acids N-Acylureas or anhydrides

Diazoalkanes Carboxylic acids Esters

Epoxides Thiols Thioethers

Haloacetamides Thiols Thioethers

Imide esters Amines Amidines

Isocyanates Amines Ureas

Isocyanates Alcohols Urethanes

Isothiocyanates Amines Thioureas

Maleimides Thiols Thioethers

Sulfonic esters Amines Alkylamines

Sulfonic esters Thiols Thioethers

Sulfonic esters Carboxylic acids Esters

Sulfonic esters Alcohols Ethers

Sulfonyl halides Amines Sulfonamides

such as optionally substituted oxysuccinimidyl, oxybenzotriazolyl or aryloxy;

the acyl azides may rearrange to give isocyanates.

These reactions are known to those skilled in the art and are described in the literature. Reference may be made to the book Advanced Organic Chemistry (ISBN 0- 471 -60180-2). Another synthetic variant consists in reacting a compound (a7) with a heterocyclic compound (a8). This reaction is illustrated in the scheme below:

with A, X' p\ q, C_sat, Rs to Rio, and T_a as defined previously; Nu representing a nucleophilic group; <£ representing an electrophilic group.

The compounds (a8) are known to those skilled in the art and their synthesis is described in Comprehensive Heterocyclic Chemistry III, 2008, Chapter 4.1 1 , Pages 893-954 and Chapter 13.10, Pages 299-319. Some compounds are also commercially available.

The reagent (a10) can react with an anionic chromophore (a7) to give an anionic dye (l₃) according to the invention. The compounds (a9) and (a10) are known to those skilled in the art and are described in the literature. Some of them are commercially available.

(i₃)

with A, q, Csat, Rs to Rio, T_a and T_b as defined previously; Nu representing a nucleophilic group; <£ representing an electrophilic group.

The compounds (a4) and (a9) are known to those skilled in the art and some are commercially available.

The reagent (a12) can react with an anionic chromophore (a2) to give an anionic dye (l₃) according to the invention. The compounds (a11 ) and (a12) are known to those skilled in the art and are described in the literature. Some of them are commercially available.

(all) (al2)

with A, q, Csat, R5 to R10, T_a, T_b and (l₃) as defined previously; Nu representing a nucleophilic group; ^<£ representing an electrophilic group.

//. Composition comprising the dye of formulae (I)

Another subject of the invention is a cosmetic composition comprising at least one anionic dye containing a disulfide heterocyclic group of formula (I) as defined previously. Preferentially in said composition, the compound of formula (I) cannot represent the carboxylate forms of the compounds (A) or (B):

Besides the presence of at least one dye of formula (I), the composition of the invention may also contain a reducing agent.

Preferentially, the composition does not contain any reducing agent. The dye composition that is useful in the invention generally contains an amount of dye of formula (I) of between 0.001 % and 50% relative to the total weight of the composition. Preferably, this amount is between 0.005% and 20% by weight and even more preferentially between 0.01 % and 5% by weight relative to the total weight of the composition.

The composition according to the invention may also contain additional direct dyes different from the dyes of formula (I). These direct dyes are chosen, for example, from neutral, acidic or cationic nitrobenzene direct dyes, neutral, acidic or cationic azo direct dyes, tetraazapentamethine dyes, neutral, acidic or cationic quinone and in particular anthraquinone dyes, azine direct dyes, triarylmethane direct dyes, indoamine direct dyes and natural direct dyes.

Among the natural direct dyes, mention may be made of lawsone, juglone, alizarin, purpurin, carminic acid, kermesic acid, purpurogallin, protocatechaldehyde, indigo, isatin, curcumin, spinulosin and apigenidin. Use may also be made of extracts or decoctions comprising these natural dyes and in particular henna-based poultices or extracts.

The composition according to the invention may contain one or more oxidation bases and/or one or more couplers conventionally used for the dyeing of keratin fibres.

Among the oxidation bases, mention may be made of para-phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols, bis-para-aminophenols, ortho- aminophenols and heterocyclic bases, and the addition salts thereof. Among these couplers, mention may be made in particular of meta-phenylenediamines, meta- aminophenols, meta-diphenols, naphthalene-based couplers and heterocyclic couplers, and the addition salts thereof. The coupler(s) are each generally present in an amount of between 0.001 % and 10% by weight and preferably between 0.005% and 6% by weight relative to the total weight of the dye composition.

The oxidation base(s) present in the dye composition are each generally present in an amount of between 0.001 % and 10% by weight and preferably between 0.005% and 6% by weight relative to the total weight of the dye composition. In general, the addition salts of the oxidation bases and couplers that can be used in the context of the invention are in particular chosen from the salts of addition with an acid, such as the hydrochlorides, hydrobromides, sulfates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, phosphates and acetates, and the salts of addition with a base, such as alkali metal hydroxides, for instance sodium hydroxide, potassium hydroxide, ammonia, amines or alkanolamines. Preferably, the process of the invention does not involve any oxidation dye, and the composition comprising the anionic dye(s) of formula (I) preferably does not contain any oxidation dye. According to one particular embodiment, the dyeing process of the invention does not involve any oxidizing agent. The composition comprising the anionic dye(s) of formula (I) of the invention preferably does not comprise any oxidizing agent.

The composition according to the invention is cosmetic, i.e. it is in a cosmetic medium that is suitable for dyeing keratin materials, also called dye support, generally made up of water or of a mixture of water and at least one organic solvent. Mention may be made, as organic solvent, for example, of lower Ci-C₄ alkanols, such as ethanol and isopropanol, polyols and polyol ethers, such as 2-butoxyethanol, propylene glycol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether or diethylene glycol monomethyl ether, and also aromatic alcohols, such as benzyl alcohol or phenoxyethanol, and mixtures thereof.

When they are present, the solvents are preferably 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 composition according to the invention may also contain various adjuvants conventionally used in hair dye compositions, such as anionic, cationic, non-ionic, amphoteric or zwitterionic surfactants or mixtures thereof, anionic, cationic, non-ionic, amphoteric or zwitterionic polymers or mixtures thereof, mineral or organic thickeners, and in particular anionic, cationic, non-ionic and amphoteric polymeric associative thickeners, antioxidants, penetrants, sequestrants, fragrances, buffers, dispersants, conditioning agents, for instance volatile or non-volatile, modified or unmodified silicones such as amino silicones, film-forming agents, ceramides, preserving agents, opacifiers and conductive polymers.

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

Needless to say, those 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 composition according to the invention is generally between 3 and 14 approximately and preferably between 5 and 1 1 approximately. It can be adjusted to the desired value by means of acidifying or basifying agents regularly used in the dyeing of keratin fibres or alternatively using conventional 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, examples that may be mentioned include aqueous ammonia, alkali metal carbonates, alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, and also derivatives thereof, sodium hydroxide, potassium hydroxide and the compounds of formula (γ) below:

^R^1 _/ ^Ra2

N - W -N

/ \

^Ra4 ^Ra3 (_γ)

in which formula (γ):

W_a is a propylene residue optionally substituted with a hydroxyl group or a Ci-C₄ alkyl radical;

- R_ai, R_a2, R_a3 and R_a4, which may be identical or different, represent a hydrogen atom or a C C₄ alkyl or d-C₄ hydroxyalkyl radical.

The composition according to the invention may be in various forms, such as in the form of a liquid, a cream or gel, or in any other form that is suitable for dyeing keratin fibres, and in particular the hair.

///. Dyeing and/or lightening process using the anionic dyes of formula (I) of the invention

Another subject of the invention is a process for dyeing and/or lightening keratin materials, in particular human keratin fibres such as the hair, consisting in applying to said materials a composition comprising at least one anionic dye of formula (I) as defined previously.

According to one particular embodiment of the invention, the process for dyeing and lightening dark keratin materials, in particular human keratin fibres such as the hair, consists in applying to said materials a composition comprising at least one anionic dye of formula (I) which is fluorescent and preferably which absorbs in the yellow, orange and red range.

In particular, the anionic dyes of formula (I) comprise a chromophore A which is anionic and derived from anionic fluorescent dyes. Mention may be made of anionic triarylmethane fluorescent direct dyes; anionic xanthene dyes and anionic quinoline dyes; each of these dyes having at least one sulfonate or carboxylate group with a cationic counterion as previously defined. Preferably, A is derived from a fluorescent dye which absorbs in the yellow, orange and red range.

According to one particular embodiment, in the process of the invention, a reducing agent is applied before, at the same time as or after the application of the composition containing at least one anionic dye of formula (I) as defined previously.

Preferentially, the reducing agent is used in the process according to the invention before the application of the anionic dye(s) of formula (I).

According to another process of the invention, the reducing agent is used at the same time as the anionic dye(s) of formula (I). For example, the anionic dye(s) of formula (I) is (are) in a cosmetic composition, a composition according to the invention, which also comprises the reducing agent. This composition is then applied to the keratin materials.

According to one variant, once the composition containing at least one anionic dye of formula (I) is applied to the keratin materials, the composition is left on for a certain time, and then the keratin materials are rinsed, and/or drained dry and/or undergo a heat treatment, in particular with steam (steampod), and/or are exposed to ultraviolet (UV) light.

The duration of the treatment after application of the composition containing at least one anionic dye of formula (I) may be short, for example from 0.1 second to 1 hour, particularly between 5 minutes and 50 minutes and more particularly between 10 and 45 minutes, and preferentially the leave-on time is 30 minutes.

The duration of the post-treatment with heat may be short, for example from 0.1 to 30 minutes. The temperature is between 40°C and 250°C, more particularly between 50°C and 200°C and preferentially from 80°C to 180°C. According to one particular embodiment, the heat treatment of the keratin fibres is performed using an iron for smoothing keratin fibres or using a hairstyling hood, a hairdryer or an infrared ray dispenser.

According to one preferred variant of the invention, the dyeing and/or lightening process according to the invention consists in applying the composition according to the invention to the keratin materials and then in draining them dry and/or subjecting them to a heat treatment particularly at a temperature of between 50 and 200°C and more preferentially between 80 and 180°C, with, for example, a smoothing iron. Optionally, in this process variant, the heat treatment is followed by rinsing.

The duration of the post-treatment with UV is between 1 second and 2 hours, preferentially 30 minutes. One particular embodiment of the invention concerns a process in which the anionic direct dye of formula (I) may be applied directly to the hair without reducing agents, free of pretreatment or post-treatment reducing agents.

A treatment with an oxidizing agent may optionally be combined. Any type of oxidizing agent that is conventional in the field may be used. Thus, it may be chosen from hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulfates, and also enzymes, among which mention may be made of peroxidases, 2-electron oxidoreductases such as uricases, and 4-electron oxygenases such as laccases. The use of hydrogen peroxide is particularly preferred.

This oxidizing agent may be applied to the fibres before or after applying the composition containing at least one anionic direct dye of formula (I) as defined previously.

Another subject of the invention is a multi-compartment dyeing device or dyeing "kit" in which a first compartment contains a dyeing composition comprising at least one compound of formula (I) and a second compartment contains an oxidizing agent.

One of these compartments may also contain one or more other dyes of direct dye or oxidation dye type.

Another subject of the invention is a multi-compartment dyeing device or dyeing "kit" in which a first compartment contains a dyeing composition comprising at least one compound of formula (I) and a second compartment contains a reducing agent.

Each of the devices mentioned above may be equipped with a means making it possible to apply the desired mixture to the hair, for instance the devices described in patent FR 2 586 913.

The examples that follow serve to illustrate the invention without, however, being limiting in nature. The thiol-based fluorescent dyes in the examples hereinafter were fully characterized by the standard spectroscopic and spectrometric methods.

I- EXAMPLES OF SYNTHESIS

General procedure: The anionic dyes of formula (I) as defined previously can be obtained according to the following scheme:

Thus, the compounds of formula (I) and in particular those of formula (l'"b) can be obtained by reacting an acid halide, preferably acid chloride (b), with the derivative (c) in an aprotic, preferably polar, solvent in the presence of a base, such as THF, in the presence of pyridine.

When necessary, the acid halide, in particular the acid chloride (b), can be prepared by the standard methods known to those skilled in the art, for example by reacting the corresponding carboxylic acid with thionyl chloride in an anhydrous aprotic solvent.

with M⁺ representing K⁺ or pyridinium Example 1 : Synthesis of dipotassium 5-{[5-(1 ,2-dithiolan-3-yl)pentanoyl]amino}-4-oxo-

3-(2-phenylhydrazinylid nate

1

Step 1:

The pentanoyi 5-(1 ,2-dithioian-3-yl) chloride used in the subsequent step is prepared according to the following procedure:

0.5 mol of lipoic acid is dissolved in 1 litre of dichloromethane and then 1.1 equivalents of thionyl chloride are added dropwise while cooling to zero degrees using an ice bath. Once the addition is complete, the medium is stirred for 2 hours in an ice bath, then the stirring is continued at ambient temperature for 2 hours, before eliminating the solvent by evaporation. The product obtained (pentanoyi 5-(1.2-dithiolan-3-yl) chloride) is dissolved again in anhydrous dichloromethane and used as it is. Step 2: Synthesis of dipotassium 5-{[5-(1,2-dithiolan-3-yl)pentanoyl]amino}-4-oxo-3-(2- phenylhydrazinylidene)-3,4-dihydronaphthalene-2, 7-disulfonate:

450 ml de anhydrous THF, 2 ml de pyridine and 4.25 g (9.09 mmol) of disodium 5- amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulfonate are introduced into a 1000 ml three-necked flask, equipped with a magnetic stirrer, a condenser, a thermometer and a dropping funnel, and then 70 ml of solution of pentanoyi 5- (1 ,2-dithiolan-3-yl) chloride in anhydrous dichloromethane (0.78 molar) are added dropwise at ambient temperature. After approximately 80 hours, the reaction is complete and the crude product is collected by centrifugation of the reaction medium. The solid obtained is washed 3 times with anhydrous THF and then dried to give 7.8 g of red solid.

The crude product is taken up with potassium hydroxide (1 .0 M solution in EtOH) with stirring for 1 hour. The salt formed is then filtered off, washed with ethanol and dried under vacuum to give 2 g of compound 1 in the form of a red solid. Analysis by proton NMR spectroscopy and mass spectrometry confirms the structure of the expected product 1.

II- DYEING EXAMPLE The dyeing evaluation is carried out according to various modes in one or two steps, with or without pre-treatment of the keratin fibre. The colour of the locks was evaluated before successive dyeing / after successive dyeing. The colour of the locks is measured with a Minolta CM2600d spectrocolorimeter (specular components included, 10° angle, illuminant D65) in the CIEL^*a^*b^* system. In this system, L^* represents the intensity of the colour, a^* indicates the green/red colour axis and b^* the blue/yellow colour axis.

The lower the value of L, the darker or more intense the colour. The higher the value of a^*, the redder the shade, and the higher the value of b^*, the yellower the shade.

Build-up of the colour:

The variation in the colouration of the locks before and after dyeing is measured by (ΔΕ) which corresponds to the colour build-up according to the following equation:

Δ E = (L^* - L₀ ^*)² + (a^* - a₀ ^*)² + (b^* - b₀ ^*)²

In this equation, L^*, a^* and b^* represent the values measured after dyeing, and L₀ ^*, a₀ ^* and bo^* represent the values measured before dyeing.

The greater the ΔΕ value, the greater the difference in colour of the lock before and after dyeing, which shows good colour build-up.

Chromaticity:

C* = ^(a*)² + (b *)²

The higher the C^* value, the more chromatic is the colour of the treated locks.

I) First mode of evaluation with reducing pre-treatment of the fibre and oxidative post- treatment:

A lock of 1 g of 90% natural white hair (90 NW) is treated in two steps with i) 10 ml of solution derived from 9 ml of water, then ii) 1 ml of 10% (w/w) thioglycolic acid solution containing 50 mg of compound of Example 1 is applied to the hair and left on the hair for 20 minutes. The lock is then treated with an 8-volume aqueous hydrogen peroxide solution for 10 minutes.

Following this application, the lock is washed with water and then with shampoo and finally dried with a hairdryer.

The colour obtained is aesthetic, chromatic and fast reddish-pink. In addition, the colour build-up is very good.

Comparative

dye C

Compared with the dyeing obtained with the comparative dye C (under the same operating conditions as with Example 1 ), the colour is significantly more intense, faster and more chromatic to the eye, with the compound of the invention vs the comparative. Furthermore, it appears that the build-up is much greater than with the comparative. These visual observations were corroborated with the spectrocolorimetric results below:

II) Second mode of evaluation without reducing pre-treatment or oxidative post- treatment:

A lock of 1 g of 90% natural white hair is treated with 50 mg of Example 1 dissolved in 10 ml of water. This solution is applied to the lock of hair with a leave-on time of 30 minutes on a hot plate at a temperature of 37°C.

After removal of the excess formula, the lock is washed with water and then with shampoo and finally dried with a hairdryer. The colour obtained is reddish-pink.

Compared with the dyeing obtained with the comparative dye C, the same tendency as with the previous process was observed for the process of the invention. This was corroborated with the spectrocolorimetric results below:

The colour of the hair is measured with co orimetry.

Measurements L,a,b L^* (D65) a^* (D65) b^* (D65) C^* (D65) A

"^c P* build-up

Lock of hair before

treatment 54.94 0.48 13.48

Example 1 52.05 12.74 9.06 15.63 13.34

Comparative 57.25 4.36 1 1.57 12.36 4.90

Claims

1. Process for dyeing keratin materials, in which a cosmetic composition comprising one or more anionic direct dyes of formula (I) below is applied to said materials:

A- (X)p - Csa, - (X')p. - Het (I)

in which formula (I):

> A represents a radical containing at least one anionic chromophore;

> Het represents a 4- to 10-membered disulfide monocyclic heterocyclic radical;

> X and X', which may be identical or different, represent:

o a linear or branched, saturated or unsaturated Ci-Ci₆ hydrocarbon-based chain, optionally interrupted and/or optionally terminated at one or two of its ends with one or more divalent groups or combinations thereof chosen from:

- -N(R)-; -0-; -S-; -C(O)-; -S(0)₂- with R, which may be identical or different, being chosen from a hydrogen atom and a Ci-C₄ alkyl or d-C₄ hydroxyalkyl radical;

an aromatic or non-aromatic, saturated or unsaturated, fused or non-fused (hetero)cyclic radical optionally comprising one or more identical or different heteroatoms, optionally substituted;

o a divalent group or the combination chosen from: -N(R)-; -0-; -S-; -C(O)-; -

S(0)₂- with R as defined previously;

preferentially, the divalent group(s) or combinations thereof are chosen from -0-; -N(R)-; -C(O)- with R chosen from a hydrogen atom and a C C₄ alkyl radical;

Csat represents a linear or branched, saturated or unsaturated, optionally substituted C1-C16 hydrocarbon-based chain.

2. Dyeing process according to the preceding claim, in which the dye of formulae (I) is such that p or p' is equal to 1 , X and X', which may be identical or different, represent the following sequence:

-(T)_t-(Z)_z-(T')_t- said sequence being linked in formulae (I), as follows:

- C_sa,-(T')_t.-(Z)_z-(T)_t-(A or Het);

in which sequence: T and T, which may be identical or different, represent one or more radicals or combinations thereof chosen from: -S(0)₂-; -0-; -S-; -N(R)-; -C(O)-; with R representing a hydrogen atom, a C1-C4 alkyl radical, C1-C4 hydroxyalkyl radical or an aryl(CrC₄)alkyl radical; and a cationic or non-cationic, preferentially monocyclic heterocycloalkyl or heteroaryl radical, preferentially containing two heteroatoms (more preferentially two nitrogen atoms) and preferentially being 5- to 7-membered, more preferentially piperazinyl or piperidinyl;

preferentially, T and T represent one or more radicals or combinations thereof chosen from -0-, -N(R)-, -C(O)-, with R chosen from a hydrogen atom and a C1-C4 alkyl radical;

the indices t and t', which may be identical or different, are 0 or 1 ;

Z represents:

-(CR1 R2)m- with m being an integer between 1 and 8 and R1 and R2, which may be identical or different, representing a hydrogen atom or a C1 -C4 alkyl, C1 -C12 alkoxy, hydroxyl, cyano, carboxy, amino, C1 -C4 alkylamino or C1 - C4 dialkylamino group, said alkyl radicals possibly forming, with the nitrogen atom which bears them, a 5- to 7-membered heterocycle, optionally comprising another heteroatom identical to or different from nitrogen; -(ΟΗ₂ΟΗ₂0)_ς- or -(OCH₂CH2)q- in which q is an integer between 1 and 15, or an aryl, alkylaryl or arylalkyl radical in which the alkyl radical is C1-C4 and the aryl radical is preferably C₆, being optionally substituted with at least one group SO₃M with M representing a hydrogen atom, an alkali metal or an ammonium ammonium group substituted with one or more identical or different, linear or branched Ci-Ci₈ alkyl radicals optionally bearing at least one hydroxyl;

or else Z represents:

with q as defined previously and r representing an integer between 0 and 4 inclusive, M representing an anionic counterion;

> z is O oM .

3. Dyeing process according to either one of the preceding claims, in which the dye of formula (I) is such that A is derived from acid nitro direct dyes, acid azo dyes such as diaryls or pyrrazolones, acid azine dyes, acid triarylmethane dyes, acid indoamine dyes, acid xanthene dyes, acid anthraquinone dyes, acid quinoline dyes, acid indigoid dyes and acid natural dyes; each of these dyes having at least one sulfonate or carboxylate group with a cosmetically acceptable, organic or mineral cationic counterion, preferably chosen from alkali metal or alkaline-earth metal cations such as Na⁺ or K⁺, or ammonium, (di)(tri)(Ci-C₆)alkylammonium, cationic heteroaryl such as pyridinium, imidazolium; more particularly, each of these dyes having between 1 and 5 sulfonate or carboxylate groups, preferably between 1 and 3 sulfonate or carboxylate groups; more preferentially, A is derived from diaryl anionic azo dyes.

4. Dyeing process according to any one of the preceding claims, in which the dye of formula (I) is such that C_sat represents a linear or branched, preferably linear, saturated or unsaturated, preferably saturated, divalent hydrocarbon-based chain comprising from 1 to 14 carbon atoms, preferably between 2 and 10, more preferentially between 3 and 6 carbon atoms, such as 4 carbon atoms.

5. Dyeing process according to any one of the preceding claims, in which the dye of formula (I) is such that Het is of formula (II) linked to the rest of the molecule by one of the substituents R₅, R₆, R₇, R₈, R₉ or R₁₀, or else said radical is linked to the rest of the molecule directly by one of the carbon atoms of the heterocycle radical in the alpha, beta position with respect to the disulfide sequence or, when q is 2 or 3, in the gamma position, in which case one of the substituents R₅, R₆, R₇, Rs, R₉ or R₁₀ is absent:

in which formula (II):

^■ R₅, R₆, Rg and R1₀, which may be identical or different, represent a hydrogen atom, or a group chosen from: i) (CrC₈)alkyl, iii) hydroxyl, iv) (di)(Ci- C₈)(alkyl)amino, v) (CrC₈)alkoxy, particularly R₅, R₆, Rg and R1₀ represent a hydrogen atom or a (CrC₄)alkyl group such as methyl, preferably R₅, R6, Rg and R1₀ represent a hydrogen atom;

^■ R₇ and R₈, which may be identical or different, represent a hydrogen atom, or a group chosen from: i) (Ci-C₈)alkyl, iii) hydroxyl, iv) (di)(Ci- C₈)(alkyl)amino, v) (d-C₈)alkoxy; particularly R₇ and R₈ are chosen from a hydrogen atom and a (CrC₄)alkyl group such as methyl, preferably R₇ and R₈ represent a hydrogen atom;

^■ or else two radicals borne by the same carbon atom R₅ and R₆, R7 and R₈, and/or R₉ and R1₀ form, together with the carbon atom which bears them, a carbonyl group;

preferentially, q is 1 ; and more particularly all the substituents R₅ to R1₀ represent a hydrogen atom.

6. Dyeing process according to any one of the preceding claims, in which the dye of formula (I) is chosen from the dyes of formulae (I'a) to (I'g) below:

'a) 'b)

(I'c) (I'd)

(I'e) (I'f)

(i'g)

in which formulae (I'a) to (I'g):

• A is as defined in Claim 1 or 3, in particular A is derived from acid nitro direct dyes, acid azo dyes such as diaryls or pyrrazolones, acid azine dyes, acid triarylmethane dyes, acid indoamine dyes, xanthene dyes, acid anthraquinone dyes, acid quinoline dyes, indigoid dyes and acid natural dyes; each of these dyes having at least one sulfonate or carboxylate group with a cationic counterion as defined previously, more particularly between 1 and 5 sulfonate or carboxylate groups, preferably between 1 and 3 sulfonate or carboxylate groups;

• X and X' are as defined in Claim 1 or 2,

• Csat is as defined in Claim 1 or 4, and preferably represents an unsubstituted, linear or branched C1-C10, more preferentially C₂-C₈, better still C₃-C₅, such as C₄, alkylene chain;

• R₅, R₆, Rg and Rio, as defined in Claim 5, particularly represent a hydrogen atom or a (Ci-C₄)alkyl group such as methyl, preferably R₅, R6, R9 and R10 represent a hydrogen atom;

• R₇ and R₈, as defined in Claim 5, particularly represent a hydrogen atom or a (CrC₄)alkyl group such as methyl, preferably R₇ and R₈ represent a hydrogen atom;

preferentially, all the substituents R₅ to Rio represent a hydrogen atom.

7. Dyeing process according to any one of the preceding claims, in which the dye of formula (I) is chosen from the dyes of formulae (l"a) and (l"b) below:

(l"b)

in which formula (I):

• X, X', p, p', Csat, Rs, R6, R7, Re, R9 and R10 are as defined in the preceding claim, q is 1 or 2, it being understood that when q is 2 then the R₇ and R₈ groups may be identical to or different from one another,

preferably, q is 1 , p is 1 and p' is 0, R₅ to R1₀ represent a hydrogen atom, X represents an amide divalent group -N(R)-C(0)- or -C(0)-N(R)- with R representing a hydrogen atom, or a C1-C4 alkyl radical; and C_sat represents an unsubstituted linear or branched, more preferentially linear, C1-C1₀ alkylene chain;

• Ri and R₂, which may be identical or different, represent a group chosen from: i) hydroxyl, ii) thiol, iii) nitro, iv) optionally substituted (CrC₆)alkyl, in particular (d- C₄)alkyl such as methyl or ethyl, v) (CrC₆)alkoxy, in particular (CrC₄)alkoxy such as ethoxy or methoxy, vi) (CrC₆)alkylthio, vii) halogen and viii) amino - NR_aR_b with R_a and R_b, which may be identical or different, representing:

o a hydrogen atom,

o a (CrC₆)alkyl group, particularly (d-C₄)alkyl group such as methyl or ethyl, said alkyl group being optionally substituted with one or more hydroxyl groups, or else

said heterocycle possibly also:

b) being substituted with one or more groups, which may be identical or different, chosen from hydroxyl, (CrC₄) alkyl optionally substituted with one or more hydroxyl groups, (CrC₄)alkyloxy such as ethoxy or methoxy, (di)(Ci-C₄)(alkyl)amino, (di)hydroxy(Ci-C₄)alkylamino;

x is an integer between 0 and 5 inclusive;

n integer between 0 and 4 inclusive;

•

, which may be present or absent, represents a benzo ring; the ring is preferably absent;

it being understood that, when x, x', t and t' are greater than or equal to 2, then respectively Ri are identical to or different from one another, R₂ are identical to or different from one another, Z are identical to or different from one another, and Z' are identical to or different from one another; preferentially, the anionic dyes of formula (I) according to the invention are chosen from those of formula (l"b).

8. Dyeing process according to any one of the preceding claims, in which the dye of formula (I) is chosen from the dyes of formula (l'"b) below:

(l"'b)

in which formula (l'"b) X, p, Z', t', q, C_sat, Ri , x, R2 and x' are as defined in the preceding claim;

preferentially:

• x represents an integer between 0 and 4 inclusive, particularly between 1 and 3, and preferably is equal to 0 or 1 ;

• x' represents an integer between 0 and 3, particularly between 1 and 2, and preferably is equal to 1 ;

• X represents an amide divalent group -N(R)-C(0)- or -C(0)-N(R)-, preferably -N(R)-C(0)- with R representing a hydrogen atom or a C1-C4 alkyl radical;

• p is 1 ;

• t' represents an integer between 1 and 3 inclusive, such as 2;

• Ri , which may be identical or different, represents a group chosen from: i) hydroxyl, ii) nitro, iv) (CrC₆)alkyl, in particular (CrC₄)alkyl such as methyl or ethyl, v) (CrC₆)alkoxy, in particular (d-C₄)alkoxy such as ethoxy or methoxy, vi) (CrC₆)alkylthio, in particular (CrC₄)alkylthio such as ethylthio or methylthio, and vii) amino -NR_aR_b with R_a and R_b, which may be identical or different, representing:

o a hydrogen atom,

ou alors o R_a and R_b form, with the nitrogen atom which bears them, a 5- or 6- membered saturated heterocycle, said heterocycle possibly also:

b) being substituted with one or more hydroxyl groups;

• R₂ which may be identical or different, represents a group chosen from: i) hydroxyl, ii) thiol, iv) (CrC₆)alkyl, in particular (Ci-C₄)alkyl such as methyl or ethyl, v) (CrC₆)alkoxy, in particular (Ci-C₄)alkoxy such as ethoxy or methoxy, vi) (CrC₆)alkylthio, in particular (Ci-C₄)alkylthio such as ethylthio or methylthio, and vii) amino -NR_aR_b with R_a and R_b, which may be identical or different, representing a hydrogen atom, or a (CrC₆)alkyl group, particularly (Ci-C₄)alkyl group such as methyl or ethyl; preferably, R₂ represents a hydroxyl or thiol group, more preferentially thiol group;

• Z', which may be identical or different, represents an -S(0)₂-0^" M⁺ group with M⁺ representing a cationic counterion, preferentially chosen from alkali metal or alkaline-earth metal cations such as Na, Mg, K and Ca, and organic cations such as ammonium NH₄ ⁺ or (di/tri)(Ci-C₄)alkylammonium;

· C_sat represents a linear or branched, preferably linear, (d-C₈)alkylene group, such as -(CH₂)_m- with m representing an integer between 2 and 8 inclusive, in particular between 3 and 6, such as m is 4;

9. Dyeing process according to any one of the preceding claims, in which the dye of formula (I) is chosen from the dyes of formula (l""b) below:

(l""b)

in which formula (l""b) C_sat, ⁺, Ri , x, R₂, and x' are as defined in the preceding claim; preferably,

- x' is 0, 1 or 2, more particularly x' is 0;

R represents a hydrogen atom or a (CrC₄)alkyl group; more preferentially, R represents a hydrogen atom; and

R₂ is positioned in position 2 or 5 on the naphthyl ring.

10. Dyeing process according to the preceding claim, in which the dye of formula (I) is chosen from the dyes of formula (l""b) with:

- x" = 0; x = 0 or 1 ;

R represents a hydrogen atom or a (CrC₄)alkyl group; more preferentially, R represents a hydrogen atom;

- Ri represents a group chosen from i) hydroxyl, ii) nitro, iii) Ci-C₄ alkylthio such as methylthio, iv) CrC₄, more preferentially CrC₂, alkoxy, such as methoxy or ethoxy, v) amino NR_aR_b with:

R_a and R_b form, together with the nitrogen atom which bears them, a 5- or 6- membered saturated heterocycle, said heterocycle possibly also:

o being substituted with one or more groups, which may be identical or different, chosen from hydroxyl, CrC₄ alkyl, C1-C4 hydroalkyl, C1-C4 alkoxy, (di)(Ci-C₄)(alkyl)amino and (di)hydroxy(Ci-C₄)alkylamino groups; and Csat denotes a saturated divalent hydrocarbon-based (or alkylene) chain containing from 2 to 8 carbon atoms, preferably from 3 to 6 carbon atoms;

particularly, the anionic dyes of formula (I) are of formula (l""b) with:

- x" = 0; x = 0 or 1 ;

- R represents a hydrogen atom; and

Ri represents a group chosen from i) hydroxyl, nitro (N0₂), iii) CrC₄ alkylthio such as methylthio, CrC₄ alkoxy such as methoxy or ethoxy, iv) amino NR_aR_b with R_a and R_b independently representing a hydrogen atom, a CrC₄ alkyl group such as methyl or ethyl; a CrC₄, more preferentially CrC₂, hydroxyalkyl group, such as hydroxyethyl, or else R_a and R_b form, with the nitrogen atom which bears them, a 5- or 6-membered saturated heterocyde chosen from pyrrolidine, piperidine and piperazine rings, said heterocyde possibly also being substituted with one or more groups, which may be identical or different, chosen from hydroxyl groups, Ci-C₄ alkyl groups such as methyl, and CrC₄ hydroalkyl groups such as hydroxyethyl; - Csat represents a (C₃-C₆)alkylene group such as butylene -(CH₂)₄--

11. Dyeing process according to any one of the preceding claims, in which the dye of formula (I) is chosen from the following dyes:

with M⁺ a cationic counterion as defined in the preceding claims, preferably alkali metal such as Na or K, or ammonium or pyridinium;

compounds 1 to 15 and also the optical isomers, geometrical isomers and tautomers thereof and the solvates such as hydrates thereof.

12. Process for dyeing keratin materials according to any one of the preceding claims, in which the composition comprising the compound(s) of formula (I) is left on, and then the keratin materials are rinsed, and/or drained dry and/or undergo a heat treatment and/or are exposed to ultraviolet (UV) light.

13. Process for dyeing and/or lightening dark keratin materials, in particular human keratin fibres such as the hair, consisting in applying to said materials a composition comprising at least one anionic dye of formula (I) which is fluorescent and preferably which absorbs in the yellow, orange and red range; in particular, the anionic dyes of formula (I) comprising a chromophore A which is anionic and derived from anionic triarylmethane fluorescent dyes; anionic xanthene dyes and anionic quinoline dyes; each of these dyes having at least one sulfonate or carboxylate group with a cationic counterion as defined previously.

14. Process for dyeing keratin materials according to any one of the preceding claims, in which a reducing agent is applied before, at the same time as or after the application of the composition containing at least one anionic dye of formula (I) as defined in any one of the preceding claims; preferentially, the reducing agent is used in the process according to the invention before the application of the anionic dye(s) of formula (I).

15. Compound of formula (I) according to any one of Claims 1 to 1 1 , it being understood that the compound of formula (I) cannot represent the carboxylate forms of the compounds (A)

(A)

16. Composition comprising one or more dyes of formula (I) according to any one of Claims 1 to 1 1 , it being understood that the dye(s) of formula (I) cannot represent the carboxylate forms of the compounds (A) or (B) as defined in the preceding claim.

17. Composition according to the preceding claim, in which the dye(s) of formula (I) is (are) present in an amount of between 0.001 % and 50% by weight relative to the total weight of the composition.

18. Use of the dyes of formula (I) as defined in Claims 1 to 1 1 , for dyeing and/or lightening human keratin materials such as human keratin fibres, in particular such as the hair.