MXPA97010148A - Composition for dyeing by oxidation of keratinic fibers, comprising 2-amino-3-hydroxy pyridine and a base of oxidation, and tint procedure - Google Patents

Abstract

The present invention relates to a composition for the oxidation dyeing of keratin fibers, in particular human querstin fibers such as hair, comprising 2-amino-3-hydroxy pyridine as a copulator, in association with at least one adequately selected oxidation base, as well as the dyeing process that uses this composition with an oxidizing agent

Description

COMPOSITION FOR. DYEING BY OXIDATION OF FIBERS KERATINES THAT COMPRISES 2-AMINO-3-HYDROXY PYRIDINE AND AN OXIDATION BASE, AND DYEING PROCEPTION FIELD OF THE INVENTION The subject of the present invention is a composition for oxidation dyeing of keratin fibers, in particular, human keratin fibers such as hair, "comprising 2-amino-3-hydroxy pyridine a title of copulator, in association with at least one base of properly selected oxidation, as well as the dyeing procedure that uses this composition with an oxidizing agent.

It is known to dye keratin fibers and, in particular, human hair with dyeing compositions containing oxidation dye precursors, in particular, ortho or para-phenylenediamines, ortho or para-aminophenols or also heterocyclic compounds such as pyrimidine derivatives, generally called bases of oxidation. The oxidation dye precursors, or oxidation bases, are colorless or sparingly colored compounds which, associated with oxidizing products, can give rise, by a process of oxidative condensation, to colored compounds and dyes.

REF: 26396 It is also known «that the shades obtained with the oxidation bases can be modified by associating them with appropriately selected couplers or color modifiers, the latter ones being particularly found among aromatic meta-diamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds such as derivatives of pyridine. The variety of molecules used at the level of oxidation bases and copulators allows obtaining a rich palette of colors. The coloration called "permanent", obtained thanks to these dyes, must, on the other hand, satisfy a certain number of demands. Thus, it should have no drawbacks on the toxicological level, should allow obtaining tonalities in the desired intensity and present a good behavior in front of external agents (light, weather, washing, perm, perspiration, rubbing). The dyes should also make it possible to cover the white hairs, and, finally, to be the least selective; that is, to obtain the smallest possible differences in coloration along the same length of the same "keratinic" fiber, which may be, in effect, sensitized differently (ie, damaged) between its point and its root. BACKGROUND OF THE INVENTION It has already been proposed, particularly in the German patent applications DE 2,714,831 and DE 2,739,227, compositions for the oxidation dyeing of keratin fibers containing 2-amino-3-hydroxy pyridine as a copulant, in association with heterocyclic oxidation bases, in particular, 2,4,5,6-tetraamino pyrimidine or with diazo compounds such as N-phenylamino aniline. Such compositions are not, however, completely satisfactory, particularly from the point of view of the behavior of the colorations obtained with respect to various aggressions which the hair may experience and, in particular, with respect to shampoos. Now, the applicant has just discovered that it is possible to obtain new non-selective and particularly resistant dyes, capable of producing intense colorations in various shades, associating the 2-amino-3-hydroxy pyridine and at least one suitably selected oxidation base. This discovery forms the basis of the present invention.

DESCRIPTION OF THE INVENTION The subject of the invention is therefore a composition for the oxidation dyeing of keratin fibers and, in particular, human keratin fibers such as hair, characterized in that it comprises, in an appropriate medium for the dye: -the 2-amino-3-hydroxy pyridine and / or at least one of its addition salts with an acid, as a copulant, - and at least one oxidation base selected from: (a) the para-phenylenediamine derivatives of formula (I), and their addition salts with an acid: in which: RX, R2 and R3 / identical or different, represent a hydrogen or halogen atom, a radical to the "Cx-C4 quilo? C1-C4r alkoxy sulfo, carboxy, monohydroxyalkyl of Cj .- ^ or polyhydroxyalkyl of C2-C4, R4 and R5, identical or different, represent a hydrogen atom, an alkyl radical of C-L-, monohydroxyalkyl of L-C,!, Polyhydroxyalkyl of C2-C4, alkoxy (L-) alkyl Carbamylalkyl of acetylaminoalkyl of C ^ d, ureidoalkyl of C1-C1 carbalkoxy (Ci-C aminoalkyl (Ci-C, sulfoalkyl of 1-C4, piperidinoalkyl of C ^, morpholinoalkyl of C ^ -, or else also R4 and R5 form, together with the nitrogen atom to which they are attached, a piperidino or morpholino heterocycle, meaning "that: at least one of the radicals R1, R2, R3, R4 and R5 is different from a hydrogen atom, - when the radicals R4 and R5 simultaneously represent a hydrogen atom and when two of the radicals R?, R2 and R3 simultaneously designate a hydrogen atom, then the radical R?, R2 or R3 which does not designate a hydrogen atom, is different from a methyl radical, - when R4 and R5 do not simultaneously represent a hydrogen atom, then at least one of the radicals R1, R2 and R3 must represent a hydrogen atom; (b) para-aminophenols, and their addition salts with an acid. The oxidation dyeing composition, according to the invention, makes it possible to obtain colorations with varied shades, selective oco and which represent excellent properties of resistance at the same time with respect to atmospheric agents such as light and weathering and with respect to perspiration and humidity. different treatments that can be experienced by the hair (washed with shampoo, permanent deformations). These properties are particularly noteworthy in what concerns the resistance of colorations to shampoos. Among the C 1 -C 4 alkyl and C 1 -C 4 alkoxy radicals of the formula (I) indicated above, mention may be made in particular of the methyl, ethyl, propyl, methyloxy and ethyloxy radicals. Among the para-phenylenediamine derivatives of formula (I) indicated above, which can be used as the oxidation base in the dyeing compositions according to the invention, mention may be made more particularly of 2-chloro-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, , 6-dimethyl paraphenylenediamine, 2,6-diethyl paraphenylenediamine, 2,5-dimethyl paraphenylenediamine, 2-methyl-5-methoxy paraphenylenediamine, 2,6-dimethyl-5-methoxy paraphenylenediamine, N, N-dimethyl paraphenylenediamine, N, N-diethyl paraphenylenediamine, N, N-dipropyl paraphenylenediamine, 4-amino N, N-diethyl 3-methyl aniline, N, N-bis- (β-hydroxyethyl) paraphenylenediamine, 4-amino, N , N-bis- (j3-hydroxyethyl) 3-methyl aniline, the 4-amino 3-chloro N, N-bis-. { β-hydroxyethyl) aniline, 4-amino N, N- (ethyl, carbamylmethyl) aniline, 4-amino 3-methyl N, N- (ethyl, carbamylmethyl) aniline, 4-amino N, N (ethyl, β > -piperidinoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, -piperidinoethyl) aniline, 4-amino N, N- (ethyl, ^ -morpholinoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, 3-morpholinoethyl) aniline, 4-amino N, N- (ethyl, ji-acetylaminoethyl) aniline, 4-amino N- (Ji-methoxyethyl) aniline, 4-amino 3-methyl N, N- (ethyl, ñ -acetylaminoethyl aniline, 4-amino N, N- (ethyl, J ^ -methylaminoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, i-mesylaminoethyl) aniline, 4-amino N, N- (ethyl, β-sulfoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, J3-sulfoethyl) aniline, N- [(4'-amino) phenyl] morpholine , N- [(4'-amino) phenyl] piperidine, 2-β-hydroxyethyl paraphenylenediamine, 2-fluoride paraphenylenediamine, 2-carboxy paraphenylenediamine, 2-sulfo paraphenylenediamine, 2-isopropyl paraphenylenediamine, N- (ß - hydroxypropyl) paraphenyle n-diamine, 2-hydroxymethyl paraphenylenediamine, N, N-dimethyl 3-methyl paraphenylenediamine, N, N- (ethyl, -hydroxyethyl) paraphenylenediamine, N- (J_ >); , -dihydroxypropyl) paraphenylenediamine, 2-hydroxyethyl-oxy-paraphenylenediamine, and its addition salts with an acid. Among the para-aminophenols which can be used as oxidation bases in the context of the compositions according to the invention, mention may be made in particular of the compounds which correspond to the following formula (II), and their addition salts with acid: wherein: R6 represents a hydrogen atom, an alkyl radical of Ci-C? , monohydroxyalkyl of C ^ d, alkoxy (Cx-C4), alkoxy (CL-C4) (C 1 -C 4) alkyl or Cx-C 4 aminoalkyl. R7 represents a hydrogen or fluorine atom, an alkyl radical of C-C4, monohydroxyalkyl of C ^ C ^ polyhydroxyalkyl of C2-C4, aminoalkyl of C1-C4, cyanoalkyl of C! -C4 or alkoxy (C ^ C alkyl) (C -C4), it being understood that at least one of the radicals R6 or R7 represents a hydrogen atom Among the para-aminophenols of formula (II) indicated above, para-aminophenol, 4-amino, may be more particularly mentioned. 3-methyl phenol, 4-amino-3-fluoro-phenol, 4-amino-3-hydroxymethyl-phenol, 4-amino-2-methyl-phenol, 4-amino-2-hydroxymethyl-phenol, 4-amino-2-methoxy-methyl phenol, 4-amino-2-aminomethyl phenol, 4-amino-2-aminomethyl) phenol, and their addition salts with an acid.

The addition salts with an acid which can be used in the context of the dyeing compositions of the invention, (2-amino-3-hydroxy pyridine and oxidation bases) are chosen in particular from hydrochlorides, hydrobromides, sulfates and tartrates. The 2-amino-3-hydroxy pyridine and / or the one or more of its addition salts with an acid, preferably represent from 0.0001 to 5% by weight approximately of the total weight of the dyeing composition, and even more preferably from 0.005 to 3. % by weight approximately of this weight. The paraphenylenediamine derivative (s) of formula (I) and / or para-aminophenols of formula (II) according to the invention and / or its addition salts with an acid preferably represent from 0.0005 to 12% by weight approximately of the total weight of the dye composition, and even more preferably from 0.005 to 6% by weight approximately of this weight. The dye compositions according to the invention can contain other couplers than 2-amino-3-hydroxy pyridine and / or other oxidation bases other than the para-phenylenediamine derivatives of formula (I) and the para-aminophenols of formula (II) and / or of the direct dyes, particularly to modify the shades or enrich them with reflections.

The appropriate medium for dyeing (or support) is generally constituted by water or by a mixture of water and at least one organic solvent to solubilize compounds that are not sufficiently soluble in water. As the organic solvent, there may be mentioned, for example, the lower alkanols of C! -C4, such as ethanol and isopropanol; glycerol; glycols and ethers of glycols such as 2-butoxyethanol, propylene glycol, propylene glycol monomethylether, monoethylether and monomethylether of diethylene glycol, and aromatic alcohols such as benzyl alcohol or phenoxyethanol, analogous products and mixtures thereof.

The solvents can be present in proportions preferably comprised between 1 and 40% by weight approximately relative to the total weight of the dyeing composition, and even more preferably between 5 and 30% by weight approximately.

The pH of the dye composition, according to the invention, is generally between 3 and 12, approximately, and even more preferably between 5 and ll approximately. It can be adjusted to the desired value by means of acidifying or alkalizing agents usually used in the dyeing of keratin fibers.

Among the acidulating agents can be mentioned, example title, mineral or organic acids, such as hydrochloric acid, phosphoric acid, acids carboxylic acids, such as tartaric acid, citric acid, lactic acid, sulfonic acids.

Among the alkalizing agents can be cited, example title, ammonia, alkali carbonates, alkanolamines such as mono-, di- and triethanolamines, as well as their derivatives, the hydroxides of sodium or potassium and the compounds of formula (III) following: N-R-N V. (III) in which R is a propylene residue optionally substituted by a hydroxyl group or C 1 -C 4 alkyl radical; R8, R9, Rlß and R11 (identical or different, represent a hydrogen atom, an alkyl radical of CL-C4 O hydroxyalkyl of C! -C4.) The dyeing composition according to the invention can also include various adjuvants conventionally used in the compositions for the dyeing of hair, such as anionic, cationic, nonionic, amphoteric, zwitterionic surfactants or their mixtures, anionic, cationic, non-ionic, amphoteric, zwitterionic or their mixtures, mineral or organic thickeners, antioxidants , penetration agents, sequestering agents, perfumes, buffers, dispersing agents, conditioning agents such as, for example, silicones, smoke-killing agents, preservatives, opacifying agents, it is understood that the person skilled in the art will take care in choosing this or these possible complementary compounds in such a way that the advantageous properties intrinsically linked with the association , according to the invention, are not, or substantially, altered by the addition (s) considered.

The dyeing composition, according to the invention, can be presented in various forms, such as in the form of liquids, creams, gels, or in any other form suitable for dyeing keratin fibers, and particularly, human hair.

The subject of the invention is also a process for dyeing keratin fibers and, in particular, human keratin fibers such as hair using the dyeing composition as defined above.

According to this process, the dyeing composition as defined above is applied to the fibers, the color revealed being at an acidic, neutral or alkaline pH with the aid of an oxidizing agent "which is added at the moment of use to the composition. dye or that is present in an oxidizing composition applied simultaneously or sequentially separately.

According to a particularly preferred embodiment of the dyeing process, according to the invention, the dyeing composition described above is mixed, at the time of use, with an oxidizing composition "containing, in a medium suitable for dyeing, at least one oxidizing agent present in an amount sufficient to develop a coloration. The obtained mixture is then applied to the keratin fibers and allowed to sit for about 3 to 50 minutes, preferably about 5 to 30 minutes, after which it is rinsed, shampooed, rinsed again and dried.

The oxidizing agent present in the oxidizing composition as defined above can be chosen from the oxidizing agents conventionally used for the oxidative dyeing of keratin fibers, and among which may be mentioned hydrogen peroxide, urea peroxide , alkali metal bromates, persalts such as perborates and persulfates. Hydrogen peroxide is particularly preferred.

The pH of the oxidizing composition including the oxidizing agent as defined above is such that after mixing with the dyeing composition, the pH of the resulting composition applied on the keratin fibers preferably ranges from about 3 to about 12 and even more. preferably between 5 and 11. It is adjusted to the desired value by means of acidulating or alkalizing agents usually used in the dyeing of the keratin fibers and as defined above.

The oxidizing composition as defined above may also include various adjuvants conventionally used in hair dyeing compositions and as defined above.

The composition "which is finally applied to the keratin fibers may be present in various forms, such as in the form of liquids, creams, gels, or in any other form suitable for dyeing the keratin fibers, and, in particular, the human hair.

Another object of the invention is a multi-compartment dyeing or "kit" device or any other multi-compartment conditioning system of which a first compartment includes the dyeing composition as defined above and a second compartment includes the oxidizing composition such as defined above. These devices can be equipped by means that allow to provide on the hair the desired mixture, such as the devices described in patent FR-2,586,913 in the name of the applicant. The examples which follow are intended to illustrate the invention without thereby limiting the scope. EXAMPLES COMPARATIVE EXAMPLES 1 and 2 The following dyeing compositions were made (contained in grams) (*): composition that is not part of the invention. It is important to appreciate «that the dyeing compositions, of examples 1 and 2, contain the same molar amount of oxidation base, that is 1.10" 3 moles (**): Common tincture support - Polyglycerolated oleic alcohol with 2 moles of glycerol 4, 0 g - Polyglycerolated oleic alcohol with 4 moles of glycerol, 78% active material (M.A.) 5.69 g M.A. - Oleic acid 3.0 g Oleic acid with 2 moles of ethylene oxide sold under the trade name ETHOMEEN 012 by the AKZO Society 7.0 g Diethylamino-propyl lauryl amine, sodium salt, 55% of M.A. 3.0 g M.A.

-Alcohol oleic 5.0 g -Orthoic acid diethanolamine 12.0 g -Propylene glycol 3.5 g - Ethyl alcohol 7.0 g - Dipropylene glycol 0.5 g - Propylene glycol monomethyl ether 9.0 g Sodium bisulphite in aqueous solution, al 35Záe M.A. 0.455 g M.A.

-Ammonium acetate 0.8 g -Antioxidant, sequestrant q.s. -Perfume, preservative c.s.

-Ammonia at 20% NH3 , Og At the time of use, each dye composition was mixed with an equal amount by weight of an oxygenated water solution in 20 volumes (6% by weight). Each resulting composition had a pH of about 10 and was applied for 30 minutes on locks of natural gray hair with 90% white. The locks of hair were then rinsed, washed with a standard shampoo and then dried. The tufts of hair thus dyed then underwent a shampoo resistance test (Ahiba-Texomat machine). For this, the strands of dyed hair were placed in a basket that was immersed in a solution of a standard shampoo. The basket was subjected to a reciprocating movement of variable frequency as well as a rotating movement that reproduces the action of a manual rubbing, which has produced the formation of foam. After 3 minutes of testing, the strands that were rinsed and then dried were removed. The strands were subjected to 6 consecutive tests of shampoos. The color of the tufts was evaluated in the MUNSELL system, before and after the chalés resistance test, by means of a CM 2002 MINOLTA colorimeter. According to the MUNSELL indication, a color is defined by the expression HV / C in which the three parameters designate respectively the hue or Hue (H), the intensity or Value (V) and the purity or Chromaticity (C), the oblique bar This expression is simply a convention and does not indicate a relationship. The color difference of each strand before and after the shampoo resistance test reflects the degradation of the coloration due to the action of the shampoos and was calculated applying the NICKERSON formula: * - »< - ', as described, for example, in "Couleur, Industrie et Techni" que "; pages 14-17; vol. #5; 1978. In this formula, / ir represents the color difference between two tufts,? H,? ^ YÁC represent the variation in absolute value of the parameters H, V and C; and C0 represents the purity of the mixture in relation to which it is desired to evaluate the color difference (purity of the hair before the test). The results are given in table II given below: (*): example "that is not part of the invention. It is observed that the coloration obtained with the dye composition of example 2, according to the invention, "which includes a paraphenylenediamine derivative of formula (I), resists the action of shampoos much better than the coloration obtained with the dye composition of the example 1 which does not form part of the invention containing 2, 4, 5, 6-tetraamino pyrimidine, compound "which does not meet the definition of the oxidation bases used, according to the invention and defined above, and which correspond to a compound of the prior art as described in the German patent application DE 2,714,831. EXAMPLES 3 and 4 COMPARATIVE The following dyeing compositions were made (contained in grams): (*): composition that is not part of the invention. It is important to note 'that the dyeing compositions of Examples 3 and 4 contain the same molar amount of oxidation base, ie 3.10 ~ 3 moles. (**): Common tincture support: It is identical to that described for examples 1 and 2 indicated above. At the time of use, each dye composition was mixed with an equal amount by weight of an oxygenated water solution at 20 volumes (• &% by weight).

Each resulting composition had a pH of about 10 and was applied for 30 minutes on tufts of gray hair permanently 90% white. The locks of hair were then rinsed, washed with a standard shampoo and then dried. The tufts of hair thus dyed then underwent a shampoo resistance test (Ahiba-Texomat machine), according to the protocol described for examples 1 and 2, indicated above. The strands were subjected to 6 tests of consecutive shampoos. The color of the tufts was evaluated in the MUNSELL system, before and after the shampoo resistance test, by means of a CM 2002 MINOLTA colorimeter. The results are given in table II given below: (*): example that is not part of the invention. It is observed that the coloration obtained with the dye composition of Example 4, according to the invention, which includes a para-phenylenediamine derivative of the formula (I), much better resists the action of the shampoos than the coloration obtained with the dye composition of Example 3 that does not form part of the invention, since it contains paraphenylenediamine, a compound that does not respond to the formula (I) of the derivatives of para-phenylenediamine which can be used according to the invention and defined above.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (15)

1. CLAIMS 1. Composition for the oxidation dyeing of keratin fibers and, in particular, of human keratin fibers such as hair, characterized in that it comprises, in a medium suitable for dyeing: -la 2 -amino-3- hydroxy pyridine and / or at least one of its addition salts with an acid, as a coupler, and at least one oxidation base selected from: (a) the para-phenylenediamine derivatives of formula (I), and their salts Addition with an acid:
2. in which: R, R 1 and R 3, identical and different, represent a hydrogen or halogen atom, an alkyl radical of C! -C4, alkoxy of CL-C4, sulfo, carboxy, monohydroxyalkyl of C! -C4 or C2-C4 polyhydroxyalkyl,
3. R4 and R5, identical or different, represent a hydrogen atom, a monohydroxyalkyl alkyl radical of C, a C2-C4 polyhydroxyalkyl, a (Cx-C4) alkoxy alkyl (L-), a carbamylalkyl-C, a mesylaminoalkyl of C] C4, acetylaminoalkyl of C ^ C ^ ureidoalkyl of ^ -C ^, carbalkoxy (CÍ-CÍ) aminoalkyl (Ci-C4), sulfoalkyl of Ci-C4, piperidinoalkyl of C! -C4, morpholinoalkyl of ^ - ^, or alternatively R4 and R5 also form, together with the nitrogen atom to which they are attached, a piperidino or morpholino heterocycle, it being understood that:
4. at least one of the radicals R1, R2, R3, R4 and R5 is different from a hydrogen atom,
5. - when the radicals R4 and R5 simultaneously represent a hydrogen atom and because two of the radicals R1; R2 and R3 simultaneously designate a hydrogen atom, while the remaining radical R?, R2 or R3 does not designate - a hydrogen atom, is different from a methyl radical, - when R4 and R5 do not simultaneously represent a hydrogen atom, then at least one of the radicals R?, R2 and R3 must represent a hydrogen atom; (b) para-aminophenols, and their addition salts with an acid. 2.Composition, according to claim 1, characterized in that "the para-phenylenediamine derivatives are chosen from 2-chloro-para-phenylenediamine, 2,3-dimethyl paraphenylenediamine, 2,6-dimethyl paraphenylenediamine, 2,6- diethyl paraphenylenediamine, 2, 5-dimethyl paraphenylenediamine, 2-methyl 5-methoxy paraphenylenediamine, 2,6-dimethyl 5-methoxy paraphenylenediamine, N, N-dimethyl paraphenylenediamine, N, N-diethyl paraphenylenediamine, N, N-dipropyl paraphenylenediamine, 4-amino N, N-diethyl 3-methyl aniline, N, N-bis- (β-hydroxyethyl) paraphenylenediamine, 4-amino N, N-bis- (p-hydroxyethyl) 3- methyl aniline, 4-amino 3-chloro N, N-bis- (β-hydroxyethyl) aniline, 4-amino N, N- (ethyl, carbamylmethyl) aniline, 4-amino 3-methyl N, N- ( ethyl, carbamylmethyl) aniline, 4-amino N, N (ethyl, β-piperidinoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, JJ -piperidinoethyl) aniline, 4-amino N, N- (ethyl, ji - morpholinoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, β -morfolinoe useful) aniline, 4-amino N, N- (ethyl, β-acetylaminoethyl) aniline, 4-amino N- (β-methoxyethyl) aniline, 4-amino 3-methyl N, N- (ethyl, Ji - acetylaminoethyl) aniline, 4-amino N, N- (ethyl, β-mesylaminoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, β-mesylaminoethyl) aniline, 4-amino N, N- ( ethyl, β-sulfoethyl) aniline, 4-amino 3-methyl N, N- (ethyl, β-sulfoethyl) aniline, N [(4'-amino) phenyl] morpholine, N- [(4'-amino) phenyl] piperidine, 2- ß-hydroxyethyl paraphenylenediamine, 2-fluoro paraphenylenediamine, 2-carboxy paraphenylenediamine, 2-sulfo paraphenylenediamine, 2-isopropyl paraphenylenediamine, N- (ß-hydroxypropyl) paraphenylenediamine, 2-hydroxymethyl paraphenylenediamine, N, N-dimethyl 3-methyl paraphenylenediamine, N, N-. { ethyl, J > -hydroxyethyl) para-phenylenediamine, N- (J3,? dihydroxypropyl) para-phenylenediamine, 2-hydroxyethyloxy paraphenylenediamine, and its addition salts with an acid. 3. Composition according to claim 1, characterized in that the para-aminophenols are chosen from the compounds of formula (II), and their addition salts with an acid:
6. wherein: R6 represents a hydrogen atom, an alkyl radical of
7. CÍ-C4, monohydroxyalkyl of (Cx-C4) alkoxy alkyl! (C-C4) or aminoalkyl of C ^, R7 represents a hydrogen or fluorine atom, an alkyl radical of Cx-C4, monohydroxyalkyl of C ^ C ^ polyhydroxyalkyl of C2-C4, aminoalkyl of Cx-C4, cyanoalkyl of Cx -C4 or (Cx-C4) alkoxy alkyl (Ci-C, it being understood that at least one of the radicals R6 or R7 represents a hydrogen atom 4. Composition according to claim 3, characterized in that the para-aminophenols are chosen between para-aminophenol, 4-amino-3-methyl phenol, 4-amino-3-fluoro-phenol, 4-amino-3-hydroxymethyl-phenol, 4-amino-2-methyl-phenol, 4-amino-2-hydroxymethyl-phenol , 4-amino-2-methoxymethyl phenol, 4-amino-2-aminomethyl phenol, 4-amino 2- (β-hydroxyethyl aminomethyl) phenol, and their addition salts with an acid. of the preceding claims, characterized in that the addition salts with an acid are chosen from the hydrochlorides, the hydrobromides, the sulfates and the tart 6. Composition according to any of the preceding claims, characterized in that the 2-amino-3-hydroxy pyridine and / or the addition salts thereof with an acid represent from 0.0001 to 5% by weight of the total weight of the dyeing composition. 7. Composition according to claim 6, characterized in that "the 2-amino-3-hydroxy pyridine and / or the addition salt (s) thereof with an acid represent from 0.005 to 3% by weight of the total weight of the dyeing composition.
8. 8. Composition according to any one of the preceding claims, characterized in that the one or more paraphenylenediamine derivatives of formula (I) and / or the para-aminophenols of formula (II) and / or their addition salts with an acid they represent from 0.0005 to 12% by weight of the total weight of the dyeing composition.
9. 9. Composition according to claim 8, characterized in that "the paraphenylenediamine derivative (s) of the formula (I) and / or the para-aminophenol (s) of the formula (II) and / or its addition salts with an acid represent 0.005. to 6% by weight of the total weight of the dyeing composition.
10. 10. Composition, according to any of the preceding claims, characterized by the fact that "the suitable medium for dyeing (or support) is constituted by water or by a mixture of water and at least one organic solvent selected from the lower alkanols of C1 -C4, glycerol, the glycols and ethers of glycols, the aromatic alcohols, the analogous products and their mixtures.
11. ll. Composition according to any of the preceding claims, characterized in that it has a pH comprised between 3 and 12.
12. 12. Composition according to any of the preceding claims, characterized in that it occurs in the form of liquids, of creams, of gels, or in any other form suitable for dyeing the keratin fibers, and particularly, of the human hair.
13. 13. Processes for dyeing keratin fibers and, in particular, for human keratin fibers such as hair, characterized in that at least one dyeing composition as defined in any one of the claims is applied to these fibers. at 12, the color being revealed at an acidic, neutral or alkaline pH with the aid of an oxidizing agent which is added at the time of use to the dyeing composition or which is present in an oxidizing composition applied simultaneously or sequentially of separate form.
14. 14. Process according to claim 13, characterized in that the oxidizing agent is chosen from hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulfates.
15. 15. Multi-compartment device, or wkit "of multi-compartment dyeing, of which a first compartment includes a dye composition as defined in any of the claims, from 1 to 12, and a second compartment that includes a oxidizing composition