WO2020002685A1

WO2020002685A1 - Method for stripping the artificial colour from keratin fibres with pyridinium salts

Info

Publication number: WO2020002685A1
Application number: PCT/EP2019/067488
Authority: WO
Inventors: Leïla Hercouet; Maxime POURRET; Simon DONCK
Original assignee: L'oreal
Priority date: 2018-06-29
Filing date: 2019-06-28
Publication date: 2020-01-02
Also published as: FR3083102A1

Abstract

The present invention relates to a method for stripping the artificial colour from keratin fibres such as the hair with particular pyridinium salts, and also to the use of particular pyridinium salts for stripping the artificial colour from human keratin fibres such as the hair.

Description

Method for stripping the artificial colour from keratin fibres with pyridinium salts

The present invention relates to a method for stripping the artificial colour from human keratin fibres such as the hair, using a composition comprising one or more particular pyridinium salts, and also to the use of a composition comprising one or more particular pyridinium salts for stripping the artificial colour from human keratin fibres such as the hair.

Many people have sought for a long time to modify the colour of their hair and in particular to mask their grey hair.

It is known practice to dye keratin fibres, in particular human keratin fibres such as the hair, to obtain "permanent" colourings with dyeing compositions containing oxidation dye precursors, which are generally known as oxidation bases, such as ortho- or para-phenylenediamines, ortho- or para-aminophenols, or heterocyclic compounds such as pyrazoles, pyrazolinones or pyrazolo-pyridines. These oxidation bases are colourless or weakly coloured compounds which, when combined with oxidizing products, may give rise to coloured compounds via a process of oxidative condensation.

It is also known that the shades obtained with these oxidation bases may be varied by combining them with couplers or colour modifiers, the latter being chosen especially from aromatic meta-diamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds such as indole or pyridine compounds. The variety of molecules used as oxidation bases and couplers allows a wide range of colours to be obtained.

The second type of dyeing is "semi-permanent” dyeing or direct dyeing, which consists in applying, to the keratin fibres, direct dyes, which are coloured and colouring molecules that have affinity for said fibres, in leaving them on for a time, and then in rinsing them off.

In order to perform these dyeing operations, the direct dyes generally used are chosen from nitrobenzene, anthraquinone, nitropyridine, azo, xanthene, acridine, azine and triarylmethane direct dyes, and natural dyes.

To vary the shades obtained in oxidation dyeing, or to enrich them with tints, oxidation dyes may be used in combination with direct dyes. The term "direct dye" means natural and/or synthetic dyes, other than oxidation dyes. They are dyes that will superficially diffuse on the fibre and dye the fibres by themselves.

The direct dye(s) may be natural or synthetic, cationic, anionic or non-ionic direct dyes.

The term "natural dyes" or "dyes of natural origin" is intended to mean dyes derived from natural materials (plant, mineral or animal origin), for instance extracts, ground material and decoctions, which have a greater or smaller concentration of dyes.

Among the natural dyes are included compounds that may be present in nature and that are reproduced by chemical (semi)synthesis.

The natural dyes may be chosen especially from spinulosin, orceins, polyphenols or ortho-diphenols (also known as ODPs in the rest of the description) and all extracts rich in ODPs, curcumin, indole derivatives such as isatin or indole- 2, 3-dione, indigoids including indigo, phthalocyanines and porphyrins in particular complexed to a metal, glycosyl or non-glycosyl iridoids, chromene dyes, anthraquinone and naphthoquinone dyes such as lawsone or henna, juglone, spinulosin, chromene or chroman dyes, such as neoflavanols and neoflavanones, flavanols; and anthocyanidols. Use may also be made of extracts or decoctions containing these natural dyes and especially plant extracts or poultices containing said dyes.

For various reasons, such as the wish to partially or totally modify the shade thus given to the head of hair by oxidation dyeing or direct dyeing, in particular dyeing based on natural dyes as described previously, or the wish to remove this coloration, the user may be led to wish to partially or totally destroy the dyes thus formed or introduced into or onto the hair. Stripping of the artificial colour of the keratin fibres is then performed.

The term“artificial colour” is intended to mean a colour obtained by means of the two types of dyeing described above.

This stripping is generally performed via methods using oxidizing or reducing systems.

However, the prior art stripping techniques, which use peroxygenated reagents such as persulfates, perborates or percarbonates of ammonium or of alkali metals, that are combined at the time of use with an aqueous composition of hydrogen peroxide, are often very aggressive and modify the chemical structure of keratin. This results in poor cosmetic properties of the hair, such as difficulty in disentangling, and unpleasant feel or rough and dull hair, but especially a degradation of the keratin fibres.

This fibre degradation is particularly undesirable since it irreversibly deteriorates the physicochemical properties the hair. Said hair becomes more porous and consequently more difficult to dry, it exhibits a greater sensitivity to various other hair treatments such as dyeing or permanent- waving, and it experiences an unfavourable modification of its mechanical properties and its surface properties, which results for example in a decrease in the tensile breaking strength or an increase in the coefficient of friction. Furthermore, the solutions that exist by the oxidative route, such as persulfates, generate considerable bleaching of the fibre, which is not very desirable for the consumer.

There is thus a real need to provide a method which makes it possible to overcome these drawbacks.

The applicant has thus discovered, surprisingly, that the use of pyridinium salts of formula (I), as defined below, for stripping the artificial colour from human keratin fibres, preferably the hair, makes it possible to overcome the drawbacks described above.

A subject of the invention is thus a method for stripping the artificial colour from human keratin fibres such as the hair, which comprises applying to said artificially dyed fibres, a composition comprising one or more pyridinium salts as defined below by formula (I).

Another subject of the invention is a method implementing:

- a step of dyeing human keratin fibres such as the hair using a dye composition comprising one or more dyes chosen from oxidation dyes and/or direct dyes, in particular from natural direct dyes such as henna,

- a step of stripping the artificial colour from said fibres using a composition comprising one or more pyridinium salts of formula (I) as defined below.

Finally, a subject of the invention is the use of a composition comprising one or more pyridinium salts of formula (I) as defined below, for stripping the artificial colour from human keratin fibres such as the hair.

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

In the text hereinbelow, unless otherwise indicated, the limits of a range of values are included in that range, notably in the expressions“ between " and“ ranging from ... to ...". The expression "at least one" used in the present description is equivalent to the expression " one or more" .

For the purposes of the present invention, the expression“stripping the artificial colour from human keratin fibres such as the hair” is intended to mean removing the artificial colour from human keratin fibres such as the hair, previously dyed using an oxidation dyeing and/or direct dyeing composition, in particular using a composition comprising a natural direct dye such as henna.

The stripping method differs from a method for bleaching and/or lightening keratin fibres such as the hair which aims to degrade the melanin pigments of the hair.

In the context of the invention, use is made of one or more compounds of formula (I) and also the addition salts thereof and/or the solvates thereof, for stripping the artificial colour from human keratin fibres such as the hair:

formula I

in which:

• R¹, R², R³, R⁴ and R⁵, which may be identical or different, represent:

- a hydrogen or halogen atom,

- a linear or branched Ci-Cio alkyl radical, optionally substituted with one or more hydroxyl, Ci-Cio alkoxy, Ci-C₄ hydroxyalkyl and -NR⁷R⁸ groups,

- a linear or branched Ci-Cio alkoxy radical, optionally substituted with one or more hydroxyl, Ci-Cio alkoxy, Ci-C₄ hydroxyalkyl and -NR⁷R⁸ groups,

- a -CO2R⁹ radical, or

- a -COR¹⁰ radical,

• or two adjacent radicals R¹ and R², R² and R³, R³ and R⁴ and/or R⁴ and R⁵ can form together with the carbon atoms to which they are attached a cycloalkyl group including 5 to 10 members or an aryl group including 6 to 10 members, it being understood that said cycloalkyl or aryl group optionally comprises one or more heteroatoms and is optionally substituted with one or more halogen atoms, one or more linear or branched Ci-Cio alkyl radicals, one or more linear or branched Ci- Cio alkoxy radicals, one or more hydroxyl groups, one or more Ci-C₄

hydroxyalkyl radicals and one or more -NR⁷R⁸ groups;

• ALK represents a linear or branched, saturated or unsaturated Ci-Cio alkyl radical;

• R⁶ represents:

- a hydrogen atom or a halogen atom,

- a linear or branched, saturated or unsaturated Ci-Cio alkyl radical, optionally interrupted by one or more heteroatoms chosen from oxygen and nitrogen and/or optionally substituted with one or more hydroxyl, Ci-Cio alkoxy, Ci-C₄ hydroxyalkyl and -NR⁷R⁸ groups;

- an aryl radical including 5 to 12 members optionally substituted with one or more halogen atoms, one or more linear or branched Ci-Cio alkyl radicals, one or more linear or branched Ci-Cio alkoxy radicals, one or more hydroxyl groups, one or more C1-C4 hydroxyalkyl radicals and one or more -NR⁷R⁸ groups;

• X represents a heteroatom chosen from an oxygen atom or a sulfur atom, or an - NR¹¹ radical;

• R⁷, R⁸, R⁹, R¹⁰, and R¹¹, which may be identical or different, denote a hydrogen atom or a linear or branched C1-C10 alkyl radical optionally substituted with one or more hydroxyl or C1-C10 alkoxy, C1-C4 hydroxyalkyl and amino groups;

• it being understood that one of the substituents Ri or Rs may form with the substituent R₆ a heterocycle comprising 5 to 8 members optionally substituted in particular by one or more oxo groups;

• Q represents an anion or a mixture of organic or inorganic anions ensuring the electrical neutrality of the compounds of formula (I).

The term“anion or a mixture of anions ensuring the electrical neutrality of the compounds of formula (I)” is intended to mean an anion or an anionic group derived from an organic or mineral acid salt which counterbalances the cationic charge of the compound; more particularly, the anionic counterion is chosen from: i) halides such as chloride or bromide; ii) nitrates; iii) sulfonates, including C1-C6 alkylsulfonates: Alk-S(0)20 such as methanesulfonate or mesylate and

ethanesulfonate; iv) arylsulfonates: Ar-S(0)20 such as benzenesulfonate and toluenesulfonate or tosylate; v) citrate; vi) succinate; vii) tartrate; viii) lactate; ix) alkyl sulfates: Alk-0-S(0)0 such as methyl sulfate and ethyl sulfate; x) aryl sulfates: Ar-0-S(0)0 such as benzene sulfate and toluene sulfate; xi) alkoxy sulfates: Alk-O- S(0)₂0 such as methoxy sulfate and ethoxy sulfate; xii) aryloxy sulfates: Ar-O- S(0)₂0 , xiii) phosphates 0=P(0H)₂-0 , 0=P(0 )₂-0H 0=P(0 )₃, H0-[P(0)(0 )]w- P(0)(0 )₂ with w being an integer; xiv) acetate; xv) triflate; and xvi) borates such as tetrafluoroborate, xvii) disulfate (0=)₂S(0 )₂ or S0₄ ² and monosulfate HS0₄ , xviii) carbonate CO3² or hydrogen carbonate HCO3 ; the anionic counterion, derived from the organic or mineral acid salt, ensures the electrical neutrality of the molecule: thus, it is understood that when the anion comprises several anionic charges, then the same anion can serve for the electrical neutrality of several cationic groups in the same molecule or else may serve for the electrical neutrality of several molecules.

Q represents an anion or a mixture of organic or inorganic anions that ensure electrical neutrality in compounds of formula (I).

Preferably, Q is an anion chosen from halides, in particular chloride, bromide and iodide, sulfates, phosphates; carbonate; hydrogen carbonate; methanesulfonate; para-toluenesulfonate; camphorsulfonate; tartrate; citrate; lactate; and acetate.

More preferentially, Q is an anion chosen from para-toluenesulfonate and halides, particularly chloride.

Preferably, X represents an oxygen atom.

Preferably, ALK represents a linear C1-C1₀ alkylene radical, a linear C₂-Cio alkenylene radical or a linear C₂-Cio alkylnylene radical.

Preferentially, ALK represents a linear C1-C1₀ alkylene radical, more preferentially a linear Ci-C₄ alkylene radical, especially a methylene (-CH₂-) group.

Preferably, R¹ and R⁵ represent:

- a hydrogen atom, or

- a Ci-C₄ alkyl radical such as methyl.

Preferably, R² and R⁴, which may be identical or different, represent:

- a hydrogen atom,

- a linear or branched C1-C1₀ alkyl radical, optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, and -NR⁷R⁸ groups with R⁷ and R⁸ having the definition previously indicated in formula (I),

- a linear or branched C1-C1₀ alkoxy radical, optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, and -NR⁷R⁸ groups with R⁷ and R⁸ having the definition previously indicated in formula (I),

- a -C0₂H radical,

- a -C0₂R⁹ radical with R⁹ having the definition previously indicated in formula (I), or a -COR¹⁰ radical with R¹⁰ having the definition previously indicated in formula (I).

More preferentially, R² and R⁴ represent a hydrogen atom or a linear C1-C4 alkyl radical, in particular a methyl radical.

Preferably, R³ represents:

a hydrogen atom,

a linear or branched C2-C1₀ alkyl radical, optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, and -NR⁷R⁸ groups with R⁷ and R⁸ having the definition previously indicated in formula (I),

a linear or branched C1-C1₀ alkoxy radical , optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, C1-C4 hydroxyalkyl, and -NR⁷R⁸ groups with R⁷ and R⁸ having the definition previously indicated in formula (I),

a -CO2R⁹ radical with R⁹ having the definition previously indicated in formula (I), and

a -COR¹⁰ radical with R¹⁰ having the definition previously indicated in formula (I).

More preferentially, R³ represents a hydrogen atom or a -COR¹⁰ radical with R¹⁰ denoting a linear C1-C1₀ alkyl radical , particularly a linear C1-C4 alkyl radical.

Even more preferentially, R³ represents a hydrogen atom or a -COCH₃ radical.

Preferably, R⁶ represents:

a hydrogen atom,

a linear C1-C1₀ alkyl radical, a linear C2-C1₀ alkenyl radical or a linear C2-C1₀ alkylnyl radical optionally interrupted by one or more heteroatoms chosen from oxygen and nitrogen and/or optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, C1-C4 hydroxyalkyl and -NR⁷R⁸ groups with R⁷ and R⁸ having the definition previously indicated in formula (I).

More preferentially, R⁶ represents a linear C1-C₆ alkyl radical and more particularly a linear C1-C4 alkyl radical such as methyl or ethyl, more preferentially methyl.

Preferably, R⁷, R⁸, R⁹ and R¹⁰, which may be identical or different, denote a linear or branched C1-C1₀ alkyl radical optionally substituted with one or more hydroxyl or C1-C1₀ alkoxy and amino groups;

More preferentially, R⁷, R⁸, R⁹ and R¹⁰, which may be identical or different, denote a linear C1-C4 alkyl radical.

Preferably, R11 represents a hydrogen atom. According to one embodiment, Ri, R₂, R₃, R₄ and Rs represent a hydrogen atom.

According to another embodiment, R¹ and R⁵ represent a hydrogen atom or a C1-C4 alkyl radical, in particular a methyl radical, R² and R⁴ represent a hydrogen atom or a linear C1-C4 alkyl radical, in particular a methyl radical, R³ represents a hydrogen atom or a -COR¹⁰ radical with R¹⁰ denoting a linear C1-C4 alkyl radical, R⁶ represents a linear C1-C₆ alkyl radical, in particular a linear C1-C4 alkyl radical.

In accordance with this embodiment, X is preferably an oxygen atom.

In accordance with this embodiment, ALK represents a linear C1-C1₀ alkylene radical, more preferentially a linear C1-C4 alkylene radical , in particular a methylene (-CH2-) group.

In one particular embodiment, the pyridinium salts used in the stripping method of the invention are particular compounds of formula (II) and also the addition salts thereof and/or the solvates thereof such as the hydrates:

formula (II)

in which:

• R¹ and R⁵ represent a hydrogen atom or a C1-C4 alkyl radical, such as a methyl radical;

• R² and R⁴, which may be identical or different, represent:

- a hydrogen atom,

- a linear or branched C1-C1₀ alkyl radical, optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, and -NR⁷R⁸ groups,

- a linear or branched C1-C1₀ alkoxy radical, optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, and -NR⁷R⁸ groups,

- a -CO2H radical,

- a -CO2R⁹ radical, - a -COR¹⁰ radical;

• R³ represents:

- a hydrogen atom,

- a linear or branched C2-C1₀ alkyl radical, optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, and -NR⁷R⁸ groups,

- a linear or branched C1-C1₀ alkoxy radical, optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, C1-C4 hydroxyalkyl and -NR⁷R⁸ groups,

- a -CO2R⁹ radical, or

- a -COR¹⁰ radical;

• ALK represents a methylene radical;

• R⁶ represents a methyl radical;

• R⁷ and R⁸, which may be identical or different, denote a hydrogen atom or a linear or branched C1-C1₀ alkyl radical optionally substituted with one or more hydroxyl or C1-C1₀ alkoxy and amino groups;

• R⁹ and R¹⁰, which may be identical or different, denote a linear or branched C1-C1₀ alkyl radical optionally substituted with one or more hydroxyl or C1-C1₀ alkoxy and amino groups;

• Q represents an anion or a mixture of organic or inorganic anions ensuring the electrical neutrality of the compounds of formula (II).

Examples of anions are given above in the description of formula (I).

Preferentially, in formula (II), R² and R⁴, which may be identical or different, represent a hydrogen atom or a linear C1-C4 alkyl radical, in particular a methyl radical.

Preferentially, in formula (II), R³ represents a hydrogen atom or a -COR¹⁰ radical with R¹⁰ denoting a linear C1-C1₀ alkyl radical, particularly a linear C1-C4 alkyl radical.

Preferentially, in formula (II), Q is an anion chosen from para- toluenesulfonate and halides, particularly chloride.

The term "addition salts of the compounds of formulae (I) and (II) according to the invention" thus means addition salts with an organic or mineral acid, and addition salts with an organic or mineral base.

The addition salts of the compounds of formulae (I) and (II) according to the invention are in particular chosen from addition salts with an acid, such as hydrochlorides, hydrobromides, sulfates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, methanesulfonates, phosphates and acetates, and the addition salts with a base such as sodium hydroxide, potassium hydroxide, ammonia, amines or alkanolamines.

Moreover, the solvates of the compounds of formulae (I) and (II) according to the invention more particularly represent the hydrates of said compounds and/or the combination of said compounds with a linear or branched Ci to C₄ alcohol such as methanol, ethanol, isopropanol or n-propanol. Preferably, the solvates are hydrates.

The compound(s) of formula (I) are preferentially chosen from the following compounds:

and also mixtures thereof.

Preferentially, the compound of formula (I) is a l-(2-oxopropyl)pyridinium salt, better still the compound of formula (I) is l-(2-oxo-propyl)pyridinium chloride (compound 1).

Preferably, the compound(s) of formula (I) and/or the addition salt(s) thereof and/or the solvate(s) thereof is (are) used in a proportion ranging from 0.1% to 100% by weight, more preferentially from 1% to 50% by weight, better still from 2% to 20% by weight, even better still from 5% to 15% by weight, relative to the total weight of the composition.

The pH of the composition used in the invention ranges generally from 1 to 7, preferably from 1 to 6, better from 2 to 5 and better still from 2 to 4.

The method according to the invention may also use one or more chemical oxidizing agents.

Among the chemical oxidizing agents used conventionally, mention may be made of hydrogen peroxide, compounds that can produce hydrogen peroxide by hydrolysis, such as urea peroxide or persalts such as perborates, percarbonates and persulfates, hydrogen peroxide being particularly preferred.

Preferably, the chemical oxidizing agents(s) is (are) used in a proportion ranging from 2% to 20% by weight, preferentially from 5% to 15% by weight, even better still from 7% to 12% by weight, relative to the total weight of the composition.

In one preferred embodiment, the method uses one or more chemical oxidizing agents, preferably hydrogen peroxide. According to this embodiment, the method preferably uses a composition C) comprising one or more compounds of formula (I) and/or the addition salts thereof and/or the solvates thereof, and one or more chemical oxidizing agents, preferably hydrogen peroxide. The composition C) can be obtained by mixing, at the time of use (extemporaneous mixing), a

composition Cl) comprising one or more compounds of formula (I) and/or the addition salts thereof and/or the solvates thereof, and a composition C2) comprising one or more chemical oxidizing agents, preferably hydrogen peroxide.

According to the invention, the term“ready-to-use composition” is used to refer to the composition applied to the keratin fibres, such as the hair. The ready-to- use composition can result from the mixing of the compositions Cl) and C2) as previously described, and corresponding to the composition C).

The ready-to-use composition used in the method of the invention preferably comprises the compound(s) of formula (I) and/or the addition salts thereof and/or the solvates thereof in a total content ranging from 0.1% to 100% by weight, more preferentially from 1% to 50% by weight, better still from 2% to 20% by weight, even better still from 5% to 15% by weight, relative to the total weight of the ready-to-use composition.

The ready-to-use composition may also comprise one or more fatty substances, which are preferably liquid(s) (or oil(s)).

The term "fatty substance" means an organic compound that is insoluble in water at ordinary temperature (25°C) and at atmospheric pressure (760 mmHg) (solubility of less than 5%, preferably less than 1% and even more preferentially less than 0.1%). They have in their structure at least one hydrocarbon-based chain comprising at least 6 carbon atoms or a sequence of at least two siloxane groups. In addition, the fatty substances are generally soluble in organic solvents under the same temperature and pressure conditions, for instance chloroform, ethanol, benzene, liquid petroleum jelly or decamethylcyclopentasiloxane.

The term "oil" is intended to mean a "fatty substance" that is liquid at ambient temperature (25°C) and at atmospheric pressure (760 mmHg or 1.013 x 10⁵ Pa).

The term "non-silicone oil" is intended to mean an oil not containing any silicon (Si) atoms and the term "silicone oil" is intended to mean an oil containing at least one silicon atom.

More particularly, the fatty substances are chosen from C₆-Ci₆

hydrocarbons, non-silicone (hydrocarbon-based) oils comprising more than 16 carbon atoms, of plant, animal, mineral or synthetic origin, triglycerides of plant or synthetic origin, fluoro oils, fatty alcohols, non-salified fatty acids, esters of fatty acid and/or of fatty alcohol other than triglycerides, non-silicone waxes other than solid fatty alcohols and than solid synthetic esters, and silicones, and mixtures thereof.

It is recalled that, for the purposes of the invention, fatty alcohols, esters and acids more particularly bear at least one linear or branched, saturated or unsaturated hydrocarbon-based group comprising 6 to 30 carbon atoms, which is optionally substituted, in particular with one or more hydroxyl groups (in particular 1 to 4). If they are unsaturated, these compounds may comprise one to three conjugated or unconjugated carbon-carbon double bonds.

As C6-C16 hydrocarbons, mention may in particular made of C6-C 16 alkanes, the latter being linear, branched, or optionally cyclic.

Examples that may be mentioned include hexane, dodecane and isoparaffins such as isohexadecane and isodecane.

Mention may also be made of the following compounds:

- a mixture of C15-C 16 branched alkanes, for example that which is sold by the company SEPPIC under the name Emogreen L15;

- a mixture of C13-C 15 linear and/or branched alkanes, for example that which is sold by the company SEPPIC under the name Emosmart L15.

The hydrocarbon-based oils comprising more than 16 carbon atoms may be linear or branched. They may be chosen from liquid paraffins, petroleum jelly, liquid petroleum jelly, polydecenes, and hydrogenated polyisobutene such as Parleam®, squalane, squalene, and mixtures thereof.

Among the hydrocarbon-based oils of plant origin, mention may be made of the refined plant perhydrosqualene sold under the name Fitoderm by the company Cognis; the plant squalane sold, for example, under the name Squalive by the company Biosynthis.

A hydrocarbon-based oil of animal origin that may be mentioned is perhydrosqualene.

The triglycerides of plant or synthetic origin are preferably chosen from liquid fatty acid triglycerides containing from 6 to 30 carbon atoms, for instance heptanoic or octanoic acid triglycerides, or alternatively, more particularly from those present in plant oils, for instance sunflower oil, com oil, soybean oil, marrow oil, grapeseed oil, sesame seed oil, hazelnut oil, apricot oil, macadamia oil, arara oil, castor oil, avocado oil, jojoba oil, shea butter oil or synthetic caprylic/capric acid triglycerides, for instance those sold by the company Stearineries Dubois or those sold under the names Miglyol® 810, 812 and 818 by the company Dynamit Nobel, and mixtures thereof.

The fluoro oils may be chosen from perfluoromethylcyclopentane and perfluoro-l,3-dimethylcyclohexane, sold under the names Flutec® PC1 and Flutec® PC3 by the company BNFL Fluorochemicals; perfluoro-l,2-dimethylcyclobutane; perfluoroalkanes such as dodecafluoropentane and tetradecafluorohexane, sold under the names PF 5050® and PF 5060® by the company 3M, or alternatively

bromoperfluorooctyl sold under the name Foralkyl® by the company Atochem; nonafluoromethoxybutane and nonafluoroethoxyisobutane; perfluoromorpholine derivatives such as 4-trifluoromethyl perfluoromorpholine sold under the name PF 5052® by the company 3M.

The fatty alcohols that are suitable for use in the invention are more particularly chosen from linear or branched, saturated or unsaturated alcohols comprising from 8 to 30 carbon atoms. Examples that may be mentioned include cetyl alcohol, stearyl alcohol and a mixture thereof (cetylstearyl alcohol), octyldodecanol, 2-butyloctanol, 2-hexyldecanol, 2-undecylpentadecanol, oleyl alcohol, linolenyl alcohol, ricinoleyl alcohol, undecylenyl alcohol and linoleyl alcohol, and mixtures thereof.

The fatty acids that may be used in the context of the invention are more particularly chosen from saturated or unsaturated carboxylic acids containing from 6 to 30 carbon atoms and in particular from 9 to 30 carbon atoms. They are advantageously chosen from myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid and isostearic acid. These fatty acids are, in the composition of the invention, not salified with organic or mineral bases, so as not to give rise to soaps.

As regards the esters of fatty acids and/or of fatty alcohols other than the triglycerides mentioned above and plant waxes, mention may be made in particular of esters of saturated or unsaturated, linear C1-C26 or branched C3-C26 aliphatic monoacids or polyacids and of saturated or unsaturated, linear C1-C26 or branched C3-C26 aliphatic monoalcohols or polyalcohols, the total carbon number of the esters being greater than or equal to 6 and more advantageously greater than or equal to 10.

Among the monoesters, mention may be made of dihydroabietyl behenate; octyldodecyl behenate; isocetyl behenate; cetyl lactate; C 12-C 15 alkyl lactate; isostearyl lactate; lauryl lactate; linoleyl lactate; oleyl lactate; (iso)stearyl octanoate; isocetyl octanoate; octyl octanoate; cetyl octanoate; decyl oleate; isocetyl isostearate; isocetyl laurate; isocetyl stearate; isodecyl octanoate; isodecyl oleate; isononyl isononanoate; isostearyl palmitate; methylacetyl ricinoleate; myristyl stearate; octyl isononanoate; 2- ethylhexyl isononanoate; octyl palmitate; octyl pelargonate; octyl stearate;

octyldodecyl erucate; oleyl erucate; ethyl and isopropyl palmitates, 2-ethylhexyl palmitate, 2-octyldecyl palmitate, alkyl myristates such as isopropyl, butyl, cetyl, 2- octyldodecyl, myristyl or stearyl myristate, hexyl stearate, butyl stearate, isobutyl stearate; dioctyl malate, hexyl laurate, 2-hexyldecyl laurate and mixtures thereof.

Still within the context of this variant, esters of C4-C22 dicarboxylic or tricarboxylic acids and of C1-C22 alcohols and esters of mono-, di- or tricarboxylic acids and of C2-C26 di-, tri-, tetra- or pentahydroxy alcohols may also be used.

Mention may especially be made of: diethyl sebacate; diisopropyl sebacate; diisopropyl adipate; di-n-propyl adipate; dioctyl adipate; diisostearyl adipate; dioctyl maleate; glyceryl undecylenate; octyldodecyl stearoyl stearate; pentaerythrityl monoricinoleate; pentaerythrityl tetraisononanoate; pentaerythrityl tetrapelargonate; pentaerythrityl tetraisostearate; pentaerythrityl tetraoctanoate; propylene glycol dicaprylate; propylene glycol dicaprate; tridecyl erucate; triisopropyl citrate;

triisostearyl citrate; glyceryl trilactate; glyceryl trioctanoate; trioctyldodecyl citrate; trioleyl citrate; propylene glycol dioctanoate; neopentyl glycol diheptanoate; diethylene glycol diisononanoate; and polyethylene glycol distearates, and mixtures thereof.

Among the esters mentioned above, it is preferred to use ethyl, isopropyl, myristyl, cetyl or stearyl palmitate, 2-ethylhexyl palmitate, 2-octyldecyl palmitate, alkyl myristates such as isopropyl, butyl, cetyl or 2-octyldodecyl myristate, hexyl stearate, butyl stearate, isobutyl stearate, dioctyl malate, hexyl laurate, 2-hexyldecyl laurate, isononyl isononanoate or cetyl octanoate, and mixtures thereof.

The composition may also comprise, as fatty ester, sugar esters and diesters of C6-C30 and preferably C12-C22 fatty acids. It is recalled that the term "sugar" means oxygen-bearing hydrocarbon-based compounds bearing several alcohol functions, with or without aldehyde or ketone functions, and which comprise at least 4 carbon atoms. These sugars may be monosaccharides, oligosaccharides or polysaccharides.

Examples of suitable sugars that may be mentioned include sucrose, glucose, galactose, ribose, fucose, maltose, fructose, mannose, arabinose, xylose and lactose, and derivatives thereof, especially alkyl derivatives, such as methyl derivatives, for instance methylglucose.

The esters of sugars and of fatty acids may especially be chosen from the group comprising the esters or mixtures of esters of sugars described previously and of linear or branched, saturated or unsaturated C6-C30, preferably C12-C22, fatty acids. If they are unsaturated, these compounds may comprise one to three conjugated or unconjugated carbon-carbon double bonds.

The esters according to this variant may also be chosen from mono-, di-, tri- and tetraesters, polyesters, and mixtures thereof.

These esters may be, for example, oleates, laurates, palmitates, myristates, behenates, cocoates, stearates, linoleates, linolenates, caprates and arachidonates, or mixtures thereof such as, in particular, oleopalmitate, oleostearate and palmitostearate mixed esters.

More particularly, use is made of monoesters and diesters and especially sucrose, glucose or methylglucose monooleate or dioleate, stearate, behenate, oleopalmitate, linoleate, linolenate or oleostearate.

An example that may be mentioned is the product sold under the name Glucate® DO by Amerchol, which is a methylglucose dioleate.

Examples of esters or mixtures of esters of sugar and of fatty acid that may also be mentioned include:

- the products sold under the names F160, F140, Fl 10, F90, F70 and SF40 by the company Crodesta, respectively denoting sucrose palmitate/stearates formed from 73% monoester and 27% diester and triester, from 61% monoester and 39% diester, triester and tetraester, from 52% monoester and 48% diester, triester and tetraester, from 45% monoester and 55% diester, triester and tetraester, from 39% monoester and 61% diester, triester and tetraester, and sucrose monolaurate; - the products sold under the name Ryoto Sugar Esters, for example referenced B370 and corresponding to sucrose behenate formed from 20% monoester and 80% diester-triester-polyester;

- the sucrose mono-dipalmito-stearate sold by the company Goldschmidt under the name Tegosoft® PSE.

The non-silicone wax(es) other than solid fatty alcohols and solid synthetic esters are chosen especially from camauba wax, candelilla wax, esparto wax, paraffin wax, ozokerite, plant waxes, such as olive tree wax, rice wax, hydrogenated jojoba wax or absolute flower waxes, such as the blackcurrant blossom essential wax sold by the company Bertin (France), or animal waxes, such as beeswaxes or modified beeswaxes (cerabellina); other waxes or waxy raw materials that may be used according to the invention are especially marine waxes, such as the wax sold by the company Sophim under the reference M82, polyethylene waxes or polyolefin waxes in general.

The fatty substance(s) do not comprise any C2-C3 oxyalkylene units.

Preferably, they do not contain any glycerol units. More particularly, the fatty substances are other than fatty acids.

More particularly, the fatty substances are chosen from compounds that are liquid or pasty at ambient temperature and at atmospheric pressure.

Preferably, the fatty substance is a compound that is liquid at a temperature of 25°C and at atmospheric pressure, or oil.

According to one preferred variant, the fatty substances are not silicone-based.

The fatty substances are preferably chosen from C6-C16 hydrocarbons, hydrocarbon-based oils comprising more than 16 carbon atoms, of plant, animal, mineral or synthetic origin, triglycerides of plant or synthetic origin, fatty alcohols, fatty acid and/or fatty alcohol esters, or mixtures thereof.

Preferably, the fatty substance is chosen from linear or branched hydrocarbon- based oils, of mineral or synthetic origin, comprising more than 16 carbon atoms, or mixtures thereof, for instance liquid petroleum jelly.

When the ready-to-use composition used in the method of the invention comprises one or more fatty substances, which are preferably liquid, the total content preferably ranges from 1% to 90% by weight, more preferentially from 10% to 80% by weight, better still from 20% to 70%, even more preferentially from 25% to 60%, even better still from 35% to 65% by weight, relative to the total weight of the ready-to-use composition. The ready-to-use composition may also comprise one or more surfactants, preferably one or more non-ionic surfactants. Preferably, the non-ionic surfactant(s) are chosen from oxyalkylenated (OA), preferably oxyethylenated, non-ionic surfactants.

According to one particular embodiment, the ready-to-use composition comprises at least one oxyalkylenated (OA) non-ionic surfactant comprising a number of OA units ranging from 1 to 9 and at least one oxyalkylenated (OA) non-ionic surfactant comprising at least 10 OA units.

The weight ratio, in the composition of the invention, of the amount of oxyalkylenated non-ionic surfactant(s) comprising a number of OA units ranging from 1 to 9 to the amount of oxyalkylenated non-ionic surfactant(s) comprising at least 10 OA units is greater than 1, preferably greater than or equal to 1.2, better still greater than or equal to 1.5 and even better still greater than or equal to 2.

Preferably, the oxyalkylenated non-ionic surfactants according to the invention are chosen from oxyethylenated non-ionic surfactants.

Preferably, according to this embodiment, the ready-to-use composition according to the invention comprises at least one oxyethylenated (OE) non-ionic surfactant comprising a number of OE units ranging from 1 to 9 and at least one oxyethylenated (OE) non-ionic surfactant comprising at least 10 OE units.

The weight ratio, in the ready-to-use composition of the invention, of the amount of oxyethylenated non-ionic surfactant(s) comprising a number of OE units ranging from 1 to 9 to the amount of oxyethylenated non-ionic surfactant(s) comprising at least 10 OE units is greater than 1, preferably greater than or equal to 1.2, better still greater than or equal to 1.5 and even better still greater than or equal to 2.

This weight ratio may range, for example, from 1.2 to 15, better still from 1.5 to 10 and even better still from 2 to 5.

The oxyethylenated non-ionic surfactants comprising a number of OE units ranging from 1 to 9 and the oxyethylenated (OE) non-ionic surfactants comprising at least 10 OE units can be chosen from the following categories:

•oxyethylenated (C8-C2₄)alkylphenols,

• saturated or unsaturated, linear or branched, oxyethylenated, C₈-C₃₀ and preferably C12-C22 fatty alcohols,

•saturated or unsaturated, linear or branched, oxyethylenated C₈-C₃₀ amides,

•esters of saturated or unsaturated, linear or branched, C₈-C₃₀ acids and of polyethylene glycols,

•polyoxyethylenated esters of saturated or unsaturated, linear or branched, Cs- C30 acids and of sorbitol, •saturated or unsaturated, oxyethylenated plant oils,

and mixtures thereof.

Preferably, the oxyethylenated non-ionic surfactant comprising at least 10 OE units and the oxyethylenated non-ionic surfactant comprising from 1 to 9 OE units are chosen from oxyethylenated, saturated or unsaturated, linear or branched, preferably linear, C8-C30, preferably C12-C22 and better still C14-C20, fatty alcohols, for instance cetyl alcohol, oleyl alcohol, oleocetyl alcohol, behenyl alcohol, cetearyl alcohol and stearyl alcohol, and mixtures thereof, and more preferably stearyl alcohol.

Use is preferably made, as oxyethylenated non-ionic surfactant comprising from 1 to 9 OE units, of oxyethylenated non-ionic surfactants comprising from 2 to 8 and preferably from 2 to 4 OE units, for instance the products of addition of ethylene oxide and stearyl alcohol such as stearyl alcohol 2 OE (CTFA name: Steareth-2).

The oxyethylenated non-ionic surfactants comprising at least 10 OE units used in the invention may in particular contain a number of oxyethylene groups, ranging from 10 to 50, preferably from 15 to 30 and better still from 15 to 25, for instance the products of addition of ethylene oxide and stearyl alcohol such as stearyl alcohol 20 OE (CTFA name: Steareth-20).

The content of oxyalkylenated, preferably oxyethylenated, non-ionic surfactant(s) comprising from 1 to 9 oxyalkylene units, preferably oxyethylene units, in the ready-to-use composition according to the invention may range from 0.5% to 15% by weight, preferably from 1% to 10% by weight and better still from 2% to 6% by weight relative to the total weight of the composition.

The content of oxyalkylenated, preferably oxyethylenated, non-ionic surfactants comprising at least 10 oxyalkylene groups, preferably oxyethylene groups, in the ready-to-use composition according to the invention may range from 0.1% to 15% by weight, preferably from 0.5% to 10% by weight and better still from 1% to 5% by weight relative to the total weight of the composition.

The total amount of oxyalkylenated, preferably oxyethylenated, non-ionic surfactants in the ready-to-use composition may range from 1% to 25% by weight, preferably from 2% to 15% by weight and better still from 3% to 7% by weight relative to the total weight of the composition.

The ready-to-use composition used in the method of the invention generally comprises water. When the composition is aqueous, the water content can range from 10% to 95%, preferably from 20% to 70%, better still from 20% to 50% by weight, relative to the total weight of the ready-to-use composition. The composition comprising one or more compounds of formulae (I) and (II) and/or the addition salts thereof and/or the solvates thereof may comprise one or more additional ingredients chosen from ionic liquids, organic solvents, anionic surfactants, cationic surfactants or non-ionic surfactants, other than those listed above, and amphoteric surfactants, cationic, anionic, non-ionic or amphoteric polymers or mixtures thereof, antidandruff agents, anti-seborrhoea agents, agents for preventing hair loss and/or for promoting hair regrowth, vitamins and provitamins including panthenol, sunscreens, mineral or organic pigments, sequestrants, plasticizers, solubilizers, acidifying agents, mineral or organic thickeners, especially polymeric thickeners, opacifiers or nacreous agents, antioxidants, hydroxy acids, fragrances, preservatives, pigments and ceramides.

Another subject of the invention is a method for stripping the artificial colour from human keratin fibres, such as the hair, which comprises the steps consisting:

- in mixing, immediately before use, one or more compounds of formula (I) defined above, and/or the addition salts thereof and/or the solvates thereof, with a composition comprising one or more chemical oxidizing agents, preferably hydrogen peroxide,

- in applying the mixture obtained to the human keratin fibres to be stripped,

- in leaving on the mixture for a sufficient time, for example between 1 minute and 1 hour, preferably between 5 and 50 minutes, more preferentially between 15 and 45 minutes, in order to obtain the desired stripping, and

- in removing the stripping mixture by rinsing with water, optionally followed by washing with a shampoo, then optionally by drying.

Another subject of the invention is a method implementing:

- a step of stripping the artificial colour from said fibres using a composition comprising one or more compounds of formula (I) and/or the addition salts thereof and/or the solvates thereof as previously described, preferably in the presence of one or more chemical oxidizing agents, preferably hydrogen peroxide.

According to this embodiment, the method preferably uses a composition C) as defined above.

Finally, a subject of the invention is the use of a composition comprising one or more compounds of formula (I) and/or the addition salts thereof and/or the solvates thereof as previously described, for stripping the artificial colour from human keratin fibres such as the hair.

The examples that follow serve to illustrate the invention without, however, being limiting in nature.

EXAMPLES

Example 1

The following oxidizing composition A was prepared from the following ingredients in the following proportions indicated as % by weight of product relative to the total weight of the composition in Table 1 :

Table 1

A Moroccan henna powder was mixed with water in a weight ratio of 1 :3 at a temperature of 50°C.

The mixture was then applied to a lock of natural hair containing 90% grey hairs, in a bath ratio of 5 : 1 , then the lock was wrapped in cellophane and the mixture was left on for 1 hour on a plate at 33°C.

The lock was then rinsed, washed with a shampoo, and then dried.

10 g of l-(2-oxo-propyl)pyridinium chloride (compound 1 according to the invention) were mixed with 90 g of oxidizing composition A. The pH was 2.5 ± 0.5. This mixture was then applied to the lock for 30 minutes, in a proportion of 10 g of mixture per 1 g of hair, at a temperature of 40°C.

The lock was then rinsed, then shampooed and dried. Example 2 (comparative example)

The following oxidizing composition B was prepared from the following ingredients in the following proportions indicated as % by weight of product relative to the total weight of the composition in Table 2:

Table 2

Another lock dyed beforehand with henna in the same way as that indicated in Example 1 was subjected to stripping using the oxidizing composition B mixed with hot water in a 1 :2 weight ratio for 30 minutes at a temperature of 33°C. 10 g of mixture were applied to 1 g of lock of hair. The lock was then rinsed, then shampooed and dried.

Example 3 (Estimation of lightening)

In order to demonstrate the impact of each of the methods on the melanin pigments of the hair, undyed natural chestnut locks (tone depth 4, TD4) were treated either with the method Example 1 using compound 1 according to the invention, or with the method of Example 2 using the oxidizing composition B. This estimation was carried out on locks that had not been artificially dyed so that the effect was not masked by the dyeing.

The colour of the locks treated in Examples 1 , 2 and 3 was then evaluated with an SF600X Datacolor spectrocolorimeter (illuminant D65, angle 10°, specular component included), in the CIELab system.

In this L* a* b* system, the three parameters denote, respectively, the colour intensity (L*), the green/red colour axis (a*) and the blue/yellow colour axis (b*). The higher the value of L*, the lighter the colour.

In the case of the stripping of the previously dyed locks of Examples 1 and 2, the colour variation between the coloured locks of hair and the locks of hair after stripping is defined by the parameter AEab* and is calculated according to the following Equation 1 :

Equation

In this Equation 1, the parameters L*, a* and b* represent the values measured on the locks of hair after stripping with:

- compound 1 of the invention combined with the oxidizing compound A or

- the oxidizing composition B mixed with water,

and the parameters Lo*, ao* and bo* represent the values measured on the locks of hair dyed with henna.

The higher the AEab* value, the better the stripping of the keratin fibres.

In the case of the treatment of the natural chestnut locks of Example 3, the colour variation between the coloured locks of hair and the locks of hair after treatment is defined by the parameter DE’ and is calculated according to the following Equation 2:

Equation 2

In this Equation 2, the parameters L’*, a’* and b’* represent the values measured on the locks of hair after treatment with:

- compound 1 of the invention combined with the oxidizing compound A or

- the oxidizing composition B mixed with water, and the parameters L’o*, a’o* and b’o* represent the values measured on the natural chestnut locks.

The lower the AE’ value, the less the lock is lightened, which corresponds to less degradation of the melanin pigments.

The results are collated in the Table 3 below.

Table 3

The method using compound 1 according to the invention results in a higher AEab* value, and thus in better stripping compared with the comparative method, on previously dyed locks.

Moreover, the treatment carried out with compound 1 on natural locks results in a lower AE’ value, and thus in less degradation of the melanin pigments of the hair compared with the comparative treatment.

Example 4

A lock was dyed with henna in the same way as that indicated in Example 1.

10 g of 2-methyl- 1 -(2 -oxo-propyl)-pyridinium chloride (compound 4 according to the invention) were mixed with 90 g of oxidizing composition A of example 1. This mixture was then applied to the lock for 30 minutes, in a proportion of 10 g of mixture per 1 g of hair, at a temperature of 40°C.

The lock was then rinsed, then shampooed and dried.

Other locks were prepared according to Examples 2 and 3.

The colour of the locks treated in Examples 4, 2 and 3 was then evaluated with the same procedure as described above, with a Konica-Minolta CM 3600A spectrocolorimeter (illuminant D65, angle 10°, specular component included), in the CIELab system .

The results are collated in the Table 4 below. Table 4

The method using compound 4 according to the invention results in a higher AEab* value, and thus in better stripping compared with the comparative method, on previously dyed locks.

Moreover, the treatment carried out with compound 4 on natural locks results in a lower DE’ value, and thus in less degradation of the melanin pigments of the hair compared with the comparative treatment.

Claims

1 . Method for stripping the artificial colour from human keratin fibres such as the hair, which comprises applying to said artificially dyed fibres a composition comprising one or more compounds of formula (I) and/or the addition salts thereof and/or the solvates thereof:

formula (I)

in which:

- a hydrogen atom or a halogen atom,

- a -CO2R⁹ radical, or

- a -COR¹⁰ radical;

• or two adjacent radicals R¹ and R², R² and R³, R³ and R⁴ and/or R⁴ and R⁵ can form together with the carbon atoms to which they are attached a cycloalkyl group including 5 to 10 members or an aryl group including 6 to 10 members, it being understood that said cycloalkyl or aryl group optionally comprises one or more heteroatoms and is optionally substituted with one or more halogen atoms, one or more linear or branched C1-C1₀ alkyl radicals, one or more linear or branched Ci- C1₀ alkoxy radicals, one or more hydroxyl groups, one or more C1-C4

hydroxyalkyl radicals and one or more -NR⁷R⁸ groups;

• ALK represents a linear or branched, saturated or unsaturated C1-C10 alkyl radical; • R⁶ represents:

- a hydrogen atom or a halogen atom,

- a linear or branched, saturated or unsaturated C1-C1₀ alkyl radical, optionally interrupted by one or more heteroatoms chosen from oxygen and nitrogen and/or optionally substituted with one or more hydroxyl, C1-C1₀ alkoxy, C1-C4 hydroxyalkyl and -NR⁷R⁸ groups;

- an aryl radical including 5 to 12 members optionally substituted with one or more halogen atoms, one or more linear or branched C1-C1₀ alkyl radicals, one or more linear or branched C1-C1₀ alkoxy radicals, one or more hydroxyl groups, one or more C1-C4 hydroxyalkyl radicals and one or more -NR⁷R⁸ groups;

• Q represents an anion or a mixture of organic or inorganic anions that ensure electrical neutrality in compounds of formula (I).

2. Method according to Claim 1 , characterized in that X represents an oxygen atom.

3. Method according to Claim 1 or 2, characterized in that ALK represents a linear C1-C10 alkylene radical, a linear C2-C10 alkenylene radical or a linear C2-C10 alkylnylene radical.

4. Method according to any one of the preceding claims, characterized in that the R¹ and R⁵ radicals represent a hydrogen atom or a C1-C4 alkyl radical, such as a methyl radical.

5. Method according to any one of the preceding claims, characterized in that the R² and R⁴ radicals, which may be identical or different, represent a hydrogen atom or a linear C1-C4 alkyl radical, in particular a methyl radical.

6. Method according to any one of the preceding claims, characterized in that R³ represents a hydrogen atom or a -COR¹⁰ radical with R¹⁰ denoting a linear Ci-Cio alkyl radical, particularly a linear C1-C4 alkyl radical.

7. Method according to any one of the preceding claims, characterized in that R⁷, R⁸, R⁹ and R¹⁰, which may be identical or different, denote a linear or branched C1-C1₀ alkyl radical optionally substituted with one or more hydroxyl or Ci- C1₀ alkoxy and amino groups.

8. Method according to any one of Claims 1 to 4, characterized in that the compound(s) of formula (I) are chosen from the compounds of formula (II) and also the addition salts thereof and the solvates thereof:

formula (II)

in which:

• R² and R⁴, which may be identical or different, represent:

- a hydrogen atom,

- a -CO2H radical,

- a -COR⁹ radical, or

- a -COR¹⁰ radical;

• R³ represents: - a hydrogen atom,

- a -CO2R⁹ radical, or

- a -COR¹⁰ radical;

• ALK represents a methylene radical;

• R⁶ represents a methylene radical;

9. Method according to any one of Claims 1 to 3, characterized in that the compound(s) of formula (I) are chosen from the following compounds:

and also mixtures thereof.

Q being as defined according to Claim 1.

10. Method according to any one of the preceding claims, characterized in that the pH of the composition ranges from 1 to 7, preferably from 1 to 6, better from 2 to 5.

1 1 . Method according to any one of the preceding claims, using one or more chemical oxidizing agents.

12. Method according to Claim 11 , characterized in that the chemical oxidizing agent is hydrogen peroxide.

13. Method for stripping the artificial colour from human keratin fibres such as the hair, using a composition comprising one or more compounds of formula (I) as defined in any one of Claims 1 to 9, and/or the addition salts thereof and/or the solvates thereof, and one or more chemical oxidizing agents, preferably hydrogen peroxide.

14. Stripping method according to Claim 13, characterized in that it comprises the steps consisting:

- in mixing, immediately before use, one or more compounds of formula (I), and/or the addition salts thereof and/or the solvates thereof, with a composition comprising one or more chemical oxidizing agents, preferably hydrogen peroxide,

- in applying the mixture obtained to the human keratin fibres to be stripped,

- in leaving on the mixture for a time sufficient to obtain the desired stripping, and

- in removing the stripping mixture by rinsing with water, followed by washing with a shampoo, then by drying.

15. Method for treating human keratin fibres such as the hair, implementing:

- a step of stripping the artificial colour from said fibres using a composition comprising one or more compounds of formula (I) as defined in any one of Claims 1 to 9 and/or the addition salts thereof and/or the solvates thereof, preferably in the presence of one or more chemical oxidizing agents, preferably hydrogen peroxide.

16. Use of a composition comprising one or more compounds of formula (I) as defined in any one of Claims 1 to 9 and/or the addition salts thereof and/or the solvates thereof, for stripping the artificial colour from human keratin fibres such as the hair.