HK1061514A - Yellow hair color dyeing composition having improved wear properties - Google Patents

Description

Yellow hair coloring compositions with improved long wear characteristics

Technical Field

The present invention relates to hair coloring compositions for dyeing hair yellow wherein the dyed hair is characterized by improved durability characteristics. More particularly, the present invention relates to hair coloring compositions for dyeing hair to a yellow or flaxen color, which retain the intensity, color brightness and color vibrancy of the dyed color even when exposed to light or shampooed.

Background

Since ancient times, people have used various methods to color hair in practice. In modern times, the most widely used method for hair dyeing is to color the hair in an oxidative dyeing process using a hair dyeing system that utilizes one or more oxidative hair coloring agents in combination with one or more oxidizing agents.

Most commonly, a peroxide agent is combined with one or more oxidative hair coloring agents, which are generally small molecules, capable of diffusing into the hair, and comprise one or more primary intermediates and one or more couplers. In this process, small molecule primary intermediates are activated using a peroxide material (e.g., hydrogen peroxide) to react with couplers to form larger sized complexes in the hair shaft to dye the hair in different shades and colors.

In order to provide a palette of colors having various shades, a source of yellow coloration is required.

For this purpose, oxidative hair coloring products sometimes use ortho-aminophenol compounds, such as 6-amino-m-cresol or ortho-aminophenol. However, the yellow color obtained is poorly stable under light. Over time, the consumer notices that the color is devitalized and the color becomes monotonous.

Yellow direct dye additives are sometimes used in oxidative hair coloring products as a source of yellow hair color. However, the colouring process using such dyed hair has the disadvantage that a fast and substantial loss of yellow colouring occurs after repeated shampooing. Moreover, the consumer may see an undesirable color change and color loss.

There is a need for a hair coloring system and hair coloring composition that produces a yellow hair color that retains its intensity, brightness and vibrancy over time, rather than a gradual loss or loss of vibrancy of color.

Summary of The Invention

The present invention relates to a composition for the oxidation dyeing of human hair, comprising, as an initial intermediate, in a suitable support or vehicle, a compound of formula

In the formula R₁And R₂(independently) is H; c_1-4Alkyl, optionally substituted with one or more hydroxy-or amino groups;

R₁and R₂May form a 5-or 6-membered heterocyclic ring optionally containing one additional N-or O-heteroatom in the ring

And

compounds of the formula

In the formula R₁And R₂Independently is H; c_1-4Alkyl or hydroxyalkyl

And at least one oxidizing agent.

The present invention also relates to a method of dyeing human hair yellow comprising applying to the hair a dyeing effective amount of a composition comprising as an initial intermediate in a suitable carrier or vehicle

In the formula R₁And R₂(independently) is H; c_1-4Alkyl, optionally substituted with one or more hydroxy-or amino groups;

R₁and R₂May form a 5-or 6-membered heterocyclic ring optionally containing one additional N-or O-heteroatom in the ring

And

compounds of the formula

In the formula R₁And R₂Independently is H; c_1-4Alkyl or hydroxyalkyl

And at least one oxidizing agent.

Detailed Description

It has been found that hair can be oxidatively dyed to a natural, linen or yellow coloration with exceptional durability characteristics using the compositions and methods of the present invention. The compositions and methods use 2, 4, 5, 6-tetraaminopyrimidine as a primary intermediate, 2, 6-dihydroxypyridine as a coupling agent, and at least one oxidizing agent. After oxidative dyeing of hair according to the present invention, the dyed hair retains its color intensity and gradually becomes brighter and more vibrant over a period of several days. The bright yellow colourations obtained have good durability, especially in light. The gradual improvement of the brightness and the vitality is unexpected and has great superiority. This effect can be used to offset the losses observed in known yellow hair coloring formulations using ortho-aminophenols, ortho-aminophenol derivatives or yellow direct dyes.

The improved yellow hair coloring compositions and methods of the present invention use pyrimidine compounds of the formula as initial intermediates

In the formula R₁And R₂Independently is H; c_1-4Alkyl, optionally substituted with one or more hydroxy-or amino groups;

R₁and R₂May form a 5-or 6-membered heterocyclic ring (e.g. piperidine or pyrrolidine), optionally containing a further N-or O-heteroatom (e.g. piperazine or morpholine)

And

pyridine compounds of the formula as coupling agents

In the formula R₁And R₂Independently is H; c_1-4Alkyl or hydroxyalkyl

And

at least one oxidizing agent, preferably a peroxide-providing agent, most preferably hydrogen peroxide (H)₂O₂) Or a precursor thereof.

Oxidative hair coloring compositions typically contain from about 0.01% to about 3.5% by weight of 2, 4, 5, 6-tetraaminopyrimidine and from about 0.01% to about 2.5% by weight of 2, 6-dihydroxypyridine. The molar ratio of starting intermediate to coupling agent is generally from about 5: 1 to about 1: 5, and may be employed in any suitable carrier or vehicle, typically an aqueous or hydroalcoholic solution, preferably an aqueous solution. The carrier or vehicle is typically up to about 40% by weight of the composition.

Optionally, the hair coloring systems and compositions of the present invention may also employ yellow direct dyes or known oxidative yellow dyes. Any suitable yellow direct dye or known oxidative yellow dye may be used and is preferably selected to provide the desired yellow coloration. The rate of loss of hair coloration due to loss of direct yellow dye or known oxidative yellow dye substantially matches the increase in yellow coloration imparted by oxidatively dyed hair obtained by the hair dyeing methods and compositions of the present invention. Suitable yellow direct dyes which may be used are N, O-bis (2-hydroxyethyl) -5-nitro-O-aminophenol, 2-amino-4-nitro-6-chlorophenol, 2-amino-5-nitrophenol and 5-nitro-8-hydroxyquinoline. Preferred known oxidative yellow dyes which may be used are selected from the group consisting of 6-amino-m-cresol, o-amino-phenol and 2-amino-m-cresol.

According to another aspect of the invention, not only 2, 4, 5, 6-tetraaminopyrimidine and 2, 6-dihydroxypyridine may be used, but one or more other primary intermediates and one or more other couplers may be used in hair coloring systems and compositions.

Suitable optional starting intermediates include, for example,

p-phenylenediamine derivatives, for example: 2-methyl-p-phenylenediamine, 2-chloro-p-phenylenediamine, N-phenyl-p-phenylenediamine, N- (2-methoxyethyl) -p-phenylenediamine, N-bis (2-hydroxyethyl) -p-phenylenediamine, 2-hydroxymethyl-p-phenylenediamine, 2- (1-hydroxyethyl) -p-phenylenediamine, 2- (2-hydroxyethyl) -p-phenylenediamine, 4' -diamino-diphenylamine, 2, 6-dimethyl-p-phenylenediamine, 2-isopropyl-p-phenylenediamine, N- (2-hydroxypropyl) -p-phenylenediamine, 2-propyl-p-phenylenediamine, 1, 3-bis [ (N-hydroxyethyl) -N- (4-aminophenyl) -amino ] -2-propanol, mixtures thereof, and mixtures thereof, 2-methyl-4-dimethylamino-aniline, 2-methoxy-p-phenylenediamine, 2, 3-dimethyl-p-phenylenediamine, 2- (1, 2-dihydroxyethyl) -p-phenylenediamine, and 2-thiophen-2-yl-benzene-1, 4-diamine;

p-aminophenol derivatives, for example: p-aminophenol, p-methylaminophenol, 3-methyl-4-aminophenol, 2-hydroxymethyl-4-aminophenol, 2-methyl-4-aminophenol, 2- (2' -hydroxyethylaminomethyl) -4-aminophenol, 2-methoxymethyl-4-aminophenol, 5-aminosalicylic acid and 1- (5-amino-2-hydroxyphenyl) -ethane-1, 2-diol;

ortho-aminophenol derivatives, for example: o-aminophenol, 2, 4-diaminophenol, 5-methyl-2-aminophenol, 6-methyl-2-aminophenol, 2-ethylamino-p-cresol and 2-amino-5-acetamidophenol and 4-methyl-2-aminophenol; and

heterocyclic derivatives, for example: 4, 5-diamino-1-methylpyrazole, 2-dimethylamino-5-aminopyridine, 1- (2-hydroxyethyl) -4, 5-diaminopyrazole, 4-hydroxy-2, 5, 6-triaminopyrimidine, 2- (2-hydroxyethylamino) -6-methoxy-3-aminopyridine and 3-amino-2-methylamino-6-methoxypyridine.

The starting intermediates may be used in the form of their free bases or acid addition salts, for example, hydrochloric, hydrobromic or sulphuric acid, and the like.

Suitable optional additional coupling agents include, for example,

phenol, resorcinol and naphthol derivatives, for example: 1, 7-dihydroxynaphthalene, resorcinol, 4-chloro-resorcinol, 1-naphthol, 2-methyl-1-naphthol, 1-acetoxy-2-methylnaphthalene, 1, 5-dihydroxynaphthalene, 2, 7-dihydroxynaphthalene, hydroquinone, 2-methylresorcinol, 1-hydroxy-6-aminonaphthalene-3-sulfonic acid, 2-isopropyl-5-methylphenol, 1, 5-dihydroxy-1, 2, 3, 4-tetrahydronaphthalene, 2-chloro-resorcinol, 2, 3-dihydroxy-1, 4-naphthoquinone and 1-naphthol-4-sulfonic acid, 1, 2, 3-trihydroxybenzene;

meta-phenylenediamines, for example: m-phenylenediamine, 2, 4-diamino-phenoxyethanol, N-bis (2-hydroxyethyl) -m-phenylenediamine, 2, 6-diaminotoluene, 2-N, N-bis (hydroxyethyl) -2, 4-diaminophenetole, 1, 3-bis (2, 4-diaminophenoxy) propane, 1-hydroxyethyl-2, 4-diaminobenzene, 2-amino-4- (2-hydroxyethylamino) anisole, 4- (2-aminoethoxy) -1, 3-diaminobenzene, 2, 4-diaminophenoxyacetic acid, 4, 6-bis (2-hydroxyethoxy) -m-phenylenediamine, 2, 4-diamino-5-methylphenylether, m-phenylenediamine, 2, 4-diamino-phenoxyethanol, N-bis (2-hydroxyethyl) -m-phenylenediamine, 2, 6-diaminotoluene, 2-N, N-bis (2, 4-diaminotoluene, 2-bis (, 2, 4-diamino-5-hydroxyethoxy-toluene, 2, 4-dimethoxy-1, 3-diaminobenzene and 2, 6-bis (2-hydroxyethylamino) toluene, 3- (2, 4-diaminophenoxy) -1-propanol;

meta-aminophenols, for example: m-aminophenol, 2-hydroxy-4- (carbamoyl-methylamino) toluene, m-carbamoyl-methylaminophenol, 6-hydroxybenzomoline, 2-hydroxy-4-aminotoluene, 2-hydroxy-4- (2-hydroxyethylamino) toluene, 4, 6-dichloro-m-amino-phenol, 2-methyl-m-aminophenol, 2-chloro-6-methyl-m-aminophenol, 2- (2-hydroxyethoxy) -5-aminophenol, 2-chloro-5-trifluoroethylaminophenol, 4-chloro-6-methyl-m-aminophenol, N-cyclopentyl-3-aminophenol, methyl-ethyl-methyl-m-aminophenol, methyl-ethyl-methyl-m-amino-2-methyl-4-methyl, N-hydroxyethyl-4-methoxy-6-methyl-m-aminophenol and 5-amino-4-methoxy-2-methylphenol; and

heterocyclic derivatives, for example: 1-phenyl-3-methyl-5-pyrazolone, 6-methoxy-8-aminoquinoline, 2, 6-dihydroxy-4-methylpyridine, 5-hydroxy-1, 4-benzodioxan, 3, 4-methylenedioxyphenol, 4- (2-hydroxyethylamino) -1, 2-methylenedioxybenzene, 2, 6-dihydroxy-3, 4-dimethylpyridine, 5-chloro-2, 3-dihydroxypyridine, 3, 5-diamino-2, 6-dimethoxypyridine, 3, 4-methylenedioxyaniline, 2, 6-bis (2-hydroxyethoxy) -3, 5-diaminopyridine, 4-hydroxyindole, pyrazolone, 2, 6-dihydroxy-4-methylpyridine, 5-hydroxy-1, 4-benzodioxan, 3, 4-methylenedioxybenzene, 2- (2-hydroxyethylamino) -1, 2-methylenedioxybenzene, 2, 6-dihydroxy-, 3-amino-5-hydroxy-2, 6-dimethoxypyridine, 5, 6-dihydroxyindole, 7-hydroxyindole, 5-hydroxyindole, 2-bromo-4, 5-methylenedioxyphenol, 6-hydroxyindole, 2-amino-3-hydroxypyridine, 2, 6-diaminopyridine, 5- (3, 5-diamino-2-pyridyloxy) -1, 3-dihydroxypentane, 3- (3, 5-diamino-2-pyridyloxy) -2-hydroxypropanol and isatin.

Preferred optional starting intermediates include:

p-phenylenediamine derivatives, for example: 2-methyl-p-phenylenediamine, N- (2-methoxyethyl) -p-phenylenediamine, N-bis (dihydroxyethyl) -p-phenylenediamine, 2- (1-hydroxyethyl) -p-phenylenediamine, 2- (2-hydroxyethyl) -p-phenylenediamine, and 2- (1, 2-dihydroxyethyl) -p-phenylenediamine;

p-aminophenol derivatives, for example: p-aminophenol, p-methylaminophenol, 3-methyl-4-aminophenol, 2-methoxymethyl-4-aminophenol and 1- (5-amino-2-hydroxyphenyl) -ethane-1, 2-diol;

ortho-aminophenol derivatives, for example: o-aminophenol, 2-ethylamino-p-cresol, 5-methyl-2-aminophenol, 6-methyl-2-aminophenol and 2-amino-5-acetaminophenol, 4-methyl-2-aminophenol; and

heterocyclic derivatives, for example: 4, 5-diamino-1-methylpyrazole, 1- (2-hydroxyethyl) -4, 5-diaminopyrazole and 2-dimethyl-amino-5-aminopyridine.

Preferred optional additional coupling agents include:

phenol, resorcinol and naphthol derivatives, for example: 2-methyl-1-naphthol, 1-acetoxy-2-methylnaphthalene, 1, 7-dihydroxynaphthalene, resorcinol, 4-chloro-resorcinol, 1-naphthol, 1, 5-dihydroxynaphthalene, 2, 7-dihydroxynaphthalene, hydroquinone, 2-methylresorcinol, and 2-isopropyl-5-methylphenol;

meta-phenylenediamines, for example: m-phenylenediamine, 2, 4-diamino-phenoxyethanol, 1, 3-bis (2, 4-diaminophenoxy) propane, 2-amino-4- (2-hydroxyethylamino) anisole and 4, 6-bis (2-hydroxyethoxy) -m-phenylenediamine, 3- (2, 4-diaminophenoxy) -1-propanol;

meta-aminophenols, for example: m-aminophenol, 6-hydroxybenzomorpholine, 2-hydroxy-4-aminotoluene, 2-hydroxy-4- (2-hydroxyethylamino) toluene and 2-methyl-m-aminophenol; and

heterocyclic derivatives, for example: 1-phenyl-3-methyl-5-pyrazolone, 3, 4-methylenedioxyphenol, 3, 4-methylenedioxyaniline, 4-hydroxyindole, 5, 6-dihydroxyindole, 7-hydroxyindole, 5-hydroxyindole, 6-hydroxyindole, isatin, 2, 6-diaminopyridine and 2-amino-3-hydroxypyridine.

Most preferred optional starting intermediates include:

p-phenylenediamine derivatives, for example: 2-methyl-p-phenylenediamine, N-bis (dihydroxyethyl) -p-phenylenediamine, 2- (1-hydroxyethyl) -p-phenylenediamine, and 2- (2-hydroxyethyl) -p-phenylenediamine;

p-aminophenol derivatives, for example: p-aminophenol, p-methylaminophenol, 3-methyl-4-aminophenol and 1- (5-amino-2-hydroxyphenyl) -ethane-1, 2-diol;

ortho-aminophenol derivatives, for example: o-aminophenol, 2-ethylamino-p-cresol, 5-methyl-2-aminophenol, 6-methyl-2-aminophenol and 2-amino-5-acetamidophenol; and

heterocyclic derivatives, for example: 1- (2-hydroxyethyl) -4, 5-diaminopyrazole.

Most preferred optional additional coupling agents include:

phenol, resorcinol and naphthol derivatives, for example: 2-methyl-1-naphthol, 1-acetoxy-2-methylnaphthalene, resorcinol, 4-chloro-resorcinol, 1-naphthol, and 2-methylresorcinol;

meta-phenylenediamines, for example: 2, 4-diamino-phenoxyethanol, 2-amino-4- (2-hydroxyethylamino) anisole, 4, 6-bis (2-hydroxyethoxy) -m-phenylenediamine, and 3- (2, 4-diaminophenoxy) -1-propanol;

meta-aminophenols, for example: m-aminophenol, 6-hydroxybenzomorpholine, 2-hydroxy-4-aminotoluene, 2-hydroxy-4- (2-hydroxyethylamino) toluene and 2-methyl-m-aminophenol; and

heterocyclic derivatives, for example: 1-phenyl-3-methyl-5-pyrazolone, 2-amino-3-hydroxypyridine and 6-hydroxyindole.

The dye composition of the present invention can be formulated into a lotion or cream or gel form by including appropriate types and amounts of surfactants, emulsifiers or polymers and alkalizing agents. Surfactants and emulsifiers may be anionic, cationic or nonionic, and they may be hydrophobic or hydrophilic. Examples of such surfactants and emulsifiers are: sodium lauryl sulfate, ammonium lauryl sulfate, cetyl alcohol, cetostearyl alcohol, oleic acid, dilinoleic acid, polyethylene glycols of various fatty alcohols, lauramide DEA, lauramide MEA, behenyltrimethylammonium chloride, cetyltrimethylammonium chloride and cocamidopropyl betaine. Examples of alkalizing agents are monoethanolamine, ammonium hydroxide, sodium hydroxide and sodium carbonate. The composition is mixed with an oxidizing agent, such as hydrogen peroxide, prior to application to the hair. At the end of the dyeing phase (which may be from 5 minutes to 40 minutes), the composition is rinsed from the hair with plain water and then with shampoo. In thatTypical dye compositions are described in the following examples:

composition (I)	Example 1	Example 2	Example 3
				Cocamidopropyl betaine	7
Cetyl alcohol		7	5
				Propylene glycol		15	3
Oleic acid	1	15	10
				Octyl polyglycoside	5
Stearyl ether-21			3
				C12-15 Pareth-3			5
Ammonium hydroxide	5	10	7
				Ethanolamine	2		3
EDTA	0.1	0.1	0.1
				Sodium sulfite	0.1	0.1	0.1
Aromatic agent	0.5	0.5	0.5
Dye:
				2, 4, 5, 6-tetraaminopyrimidine	1.0	1.0	1.0
2, 6-dihydroxypyridine	1.0	1.0	1.0
Water (W)	Proper amount to 100	Proper amount to 100	Proper amount to 100

In the following examples, untreated pidgeon hair was dyed with the oxidation dyeing compositions of the invention and the prior art compositions used as comparison. For comparison, the dyeing effect achieved by producing a yellow color with a typical prior art oxidation dyeing composition is presented, i.e., using o-aminophenol as the initial intermediate and 1-naphthol, 5-amino-o-cresol or resorcinol as the coupler. The staining solution comprises 1% by weight of the starting intermediates and couplers in 100 grams of a typical common staining matrix.

The staining solution was mixed with an equal amount of 6% hydrogen peroxide. The resulting dyeing formulation was applied to the hair and allowed to remain in contact with the hair for 30 minutes. The dyed hair was shampooed, rinsed with water and dried. After staining and exposure on a fadeometer (an instrument that simulates sun exposure), the staining results were measured with a Minolta spectrophotometer chromameter 3700d reflectometer. The Minolta chromameter 3700d spectrophotometer utilizes the reflected light from a surface and gives results in terms of CIE (International Commission on illumination) tristimulus values.These values are then mathematically converted to L^*a^*b, wherein the hue and intensity of the color vary by a magnitude close to what is perceivable by the human eye.

L^*Is colorless and ranges from black (L)^*0) to white (L)^*100); this term, called "metric brightness," is a measure of the lightness and darkness of a color, relative to the shade of gray. Color calling chromaticity coordinate a^*And b^*To determine wherein a^*Indicates red color (a)^*＞0)，b^*Represents yellow (b)^*＞0)。a^*And b^*May be given a^*Is the x-axis, b^*To assemble the graph for the y-axis, quantitative color information is provided: "metric chroma" is from the origin (a)^*＝0，b^*0) length of line to the point represented by the sample value, and metric hue angle is a^*The angle between the axis and the metric chromaticity line. Metric chroma indicates the intensity of the color reaction (i.e., how different a color is from its gray shade). Metric hue angle quantifies hue in degrees, with larger values indicating a darker yellow hue and smaller values indicating a darker red hue (or lighter yellow).

Table 1 shows the results of the comparative compositions and Table 2 shows the results of the compositions of the invention. L of undyed, untreated piment hair^*、a^*And b^*Mean baseline value of L^*72.32、a^*2.0、b^*23.2。

TABLE 1 comparative examples dye component L^* a^* b^*

A1-Naphthol/o-aminophenol 66.95.236.8

66.15.229.3 after 12 hours under the fading instrument

67.35.227.9 after 24 hours under the fading instrument

B5-amino-o-cresol/o-aminophenol 64.99.634.9

64.08.329.5 after 12 hours under the fading instrument

65.57.627.8 after 24 hours under the fading instrument

C Resorcinol/o-aminophenol 63.24.436.5

65.13.130.1 after 12 hours under the fading instrument

67.12.026.5 after 24 hours under the fading instrument

Table 2 examples dye component L^* a^* b^*

2, 6-dihydroxypyridine

2, 4, 5, 6-Tetraaminopyrimidine 55.4-1.520.5

58.10.537.5 after 1 day

61.21.144.9 after 4 days

63.20.645.2 after 5 days

63.81.648.1 after 10 days

After 10 days and thereafter

24 hours 66.72.646.8 under fading instrument

The spectrophotometer readings in table 1 indicate that the prior art oxidative yellow stains exhibit a weaker yellow coloration and poor stability under light. In contrast, the spectrophotometer readings in table 2 show that the yellow coloration with the compositions of the present invention increases in brightness after 10 days of dyeing, and that the coloration is stable under light even after 10 days of coloration followed by 24 hours of exposure to a fadeometer.

From the foregoing description of the invention, those skilled in the art will appreciate that modifications may be made thereto without departing from the spirit of the invention. Accordingly, the scope of the invention is not limited to what has been illustrated and described with respect to specific embodiments.

Claims (17)

1. A composition for the oxidation dyeing of human hair, which comprises as an initial intermediate, in a suitable carrier or vehicle, a compound of formula

In the formula R₁And R₂Independently is H; c_1-4Alkyl, optionally substituted with one or more hydroxy-or amino groups;

R₁and R₂May form a 5-or 6-membered hetero ring optionally containing one further N-or O-heteroatom in the ringRing (C)

And

compounds of the formula

In the formula R₁And R₂Independently is H; c_1-4Alkyl or hydroxyalkyl

And at least one oxidizing agent.

2. The composition of claim 1, further comprising a yellow direct dye or a known oxidative yellow dye.

3. The composition of claim 2, wherein the yellow direct dye is selected from the group consisting of:

n, O-bis (2-hydroxyethyl) -5-nitro-O-aminophenol,

2-amino-4-nitro-6-chlorophenol,

2-amino-5-nitrophenol, and

5-nitro-8-hydroxyquinoline.

4. The composition of claim 2, wherein the oxidative yellow dye is selected from the group consisting of: 6-amino-m-cresol, o-amino-phenol and 2-amino-m-cresol.

5. A human hair coloring composition for the oxidative dyeing of human hair comprising a 2, 4, 5, 6-tetraaminopyrimidine primary intermediate, a 2, 6-dihydroxypyridine coupling agent, and at least one oxidizing agent in a suitable carrier or vehicle.

6. The composition of claim 5, further comprising a yellow direct dye or a known oxidation dye.

7. The composition of claim 6, wherein the yellow direct dye is selected from the group consisting of:

n, O-bis (2-hydroxyethyl) -5-nitro-O-aminophenol,

2-amino-4-nitro-6-chlorophenol,

2-amino-5-nitrophenol, and

5-nitro-8-hydroxyquinoline.

8. The composition of claim 6, wherein the oxidative yellow dye is selected from the group consisting of: 6-amino-m-cresol, o-amino-phenol and 2-amino-m-cresol.

9. A method for oxidative dyeing of human hair to yellow comprising applying to the hair a dyeing effective amount of a composition comprising as an initial intermediate in a suitable carrier or vehicle

In the formula R₁And R₂Independently is H; c_1-4Alkyl, optionally substituted with one or more hydroxy-or amino groups;

R₁and R₂May form a 5-or 6-membered heterocyclic ring optionally containing one additional N-or O-heteroatom in the ring

And

compounds of the formula

In the formula R₁And R₂Independently is H; c_1-4Alkyl or hydroxyalkyl

And at least one oxidizing agent.

10. The method of claim 9, further comprising a yellow direct dye or a known oxidative yellow dye.

11. The method of claim 9, wherein the yellow direct dye is selected from the group consisting of:

n, O-bis (2-hydroxyethyl) -5-nitro-O-aminophenol,

2-amino-4-nitro-6-chlorophenol,

2-amino-5-nitrophenol, and

5-nitro-8-hydroxyquinoline.

12. The method of claim 9, wherein the oxidative yellow dye is selected from the group consisting of: 6-amino-m-cresol, o-amino-cresol and 2-amino-m-cresol.

13. A method for oxidative dyeing of human hair to a yellow color comprising applying to the hair a dyeing effective amount of a composition comprising 2, 4, 5, 6-tetraaminopyrimidine, 2, 6-dihydroxypyridine and at least one oxidizing agent in a suitable carrier or vehicle.

14. An improved composition for the oxidative dyeing of human hair, wherein said improved composition comprises a 2, 4, 5, 6-tetraaminopyrimidine starting intermediate, a 2, 6-dihydroxypyridine coupling agent, and at least one oxidizing agent in a suitable carrier or vehicle.

15. The composition of claim 14, further comprising a yellow direct dye or a known oxidative yellow dye.

16. The composition of claim 15, wherein the yellow direct dye is selected from the group consisting of:

n, O-bis (2-hydroxyethyl) -5-nitro-O-aminophenol,

2-amino-4-nitro-6-chlorophenol,

2-amino-5-nitrophenol, and

5-nitro-8-hydroxyquinoline.

17. The composition of claim 16, wherein the oxidative yellow dye is selected from the group consisting of: 6-amino-m-cresol, o-amino-phenol and 2-amino-m-cresol.