CA2422690A1

CA2422690A1 - Yellow hair color dyeing composition having improved wear properties

Info

Publication number: CA2422690A1
Application number: CA002422690A
Authority: CA
Inventors: Gottfried Wenke; Y. M. Michael Wong
Original assignee: Individual
Current assignee: P&G Hair Care Holding Inc
Priority date: 2000-09-21
Filing date: 2001-09-18
Publication date: 2002-03-28
Also published as: CN1205910C; JP2004509140A; EP1330231A1; MXPA03002461A; WO2002024155A1; EP1330231A4; CN1462183A; AU9105401A; AU2001291054B2

Abstract

Oxidative dyeing of hair to a natural blonde or yellow coloration with exceptional wearing properties can be obtained y use of a system for oxidative hair coloring in which the hair coloring system utilizes a compound of the formula (I) wherein R1 and R2 are independently H; C1-4 alkyl, optionally substituted with one or more hydroxy- or amino groups; R1 and R2 may form a 5-or 6-membered heterocyclic ring, optionally containing one additional N- or O-heteroatom in the ring as a primary intermediate and a compound of the formula (II) wherein R1 and R2 are independently H; C1-4 alkyl or hydroxy-alkyl as a coupler and optionally a yellow direct dye or a known oxidative yellow dye.

Description

YELLOW HAIR COLOR DYEING COMPOSITION
HAVING IMPROVED WEAR PROPERTIES
Field of the Invention This invention relates to hair coloring compositions for dyeing hair a yellow color, which dyed hair is characterized by improved wear properties.
More particularly, the invention relates to hair coloring compositions for dyeing hair a yellow or blonde color in which the dyed hair retains the dyed color intensity, color brightness and color vibrancy, even on exposure to light or shampooing.
Background of the Invention Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the most extensively used method employed to color hair is to color hair by an oxidative dyeing process employing hair coloring systems utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents. .
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of difFusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized complexes in the hair shaft to color the hair in a variety of shades and colors.
In order to provide a full palette of shades, a source for a yellow hair color is needed.

Oxidative hair color products sometimes employ o-aminophenol compounds, such as 6-amino-m-cresol or o-aminophenol for this purpose.
However, the resulting yellow color has poor stability to light. This is noticeable for the consumer in a loss of vibrancy and drabbing of the color with time.
Sometimes yellow direct dye additives are used in oxidative hair color products as a source of yellow hair color. However, the drawback of utilizing such a coloration process for dyeing of hair is the relative fast and large loss of the yellow coloration experienced after repeated shampooing. Again, the consumer will notice undesirable color changes and loss of vibrancy.
It would therefore be desirable if a hair coloring system and composition for dyeing of hair could be provided that produces a yellow coloration of the hair that retains its intensity, brightness and vibrancy over a period of time - instead of showing a gradual loss and drabbing of the color.
Summary of the Invention The present invention is directed to a human hair dyeing composition for the oxidative dyeing of human hair comprising, in a suitable carrier or vehicle, a compound of the formula N
R1 ~N~N NH

2.

wherein R~ and R2 are (independently) H; C~_4 alkyl, optionally substituted with one or more hydroxy- or amino group;
R~ and R2 may form a 5- or 6-membered heterocyclic ring optionally containing one additional N- or O- heteroatom in the ring as a primary intermediate and a compound of the formula HO N OH
wherein R~ and R2 are independently H; C~_4 alkyl or hydroxy-alkyl as a coupler and at least one oxidizing agent.
The present invention is also directed to a process for dyeing of human hair a yellow color which comprises applying to the hair a hair-dyeing effective amount of a composition containing, in a suitable carrier or vehicle, a compound of the formula N
R1 ~N~N NH

wherein R~ and R2 are (independently) H; C~_4 alkyl, optionally substituted with one or more hydroxy- or amino group;
R~ and R2 may form a 5- or 6-membered heterocyclic ring optionally containing one additional N- or O- heteroatom in the ring as a primary intermediate and a compound of the formula HO N OH
wherein R~ and R2 are independently H; C~_4 alkyl or hydroxy-alkyl as a coupler and at least one oxidizing agent.
The rate of loss of hair coloration due to loss of the direct or known oxidative yellow dye will essentially match the increase in yellow coloration imparted by the oxidatively colored hair obtained by the hair coloring process and composition of this invention.
Detailed Description of the Invenfiion It has been discovered that oxidative dyeing of hair to a natural blonde or yellow coloration with exceptional wearing properties can be obtained by the use of the present composition and process. The composition and process utilize 2,4,5,6-tetraaminopyrimidine as a primary intermediate, 2,6-dihydroxypyridine as a coupler and at least one oxidizing agent. When hair is oxidatively colored according to the present invention, the colored hair retains its intensity of coloration and turns gradually brighter and more vibrant over a period of several days. The resulting bright yellow coloration has good wearing properties, especially with regard to exposure to light. The rate of loss of hair coloration due to loss of the direct or known oxidative yellow dye will essentially match the increase in yellow coloration imparted by the oxidatively colored hair obtained by the hair coloring process and composition of this invention.
The improved yellow hair coloring composition and method of this invention employs a pyrimidine compound of the formula N
R1 ~N~N NH

wherein R~ and R2 are independently H; C~.~ alkyl, optionally substituted with one or more hydroxy- or amino group;
R~ and R2 may form a 5- or 6-membered heterocyclic ring (such as piperidine or pyrrolidine), optionally containing one additional N- or O- heteroatom in the ring (such as piperazine or morpholine) as a primary intermediate and a pyridine compound of the formula HO N OH
wherein R~ and RZ are independently H; C~_4 alkyl or hydroxy-alkyl as a coupler, and at least one oxidizing agent, preferably a peroxide providing agent, and most preferably hydrogen peroxide (H202) or precursors therefor.
The oxidative hair coloring compositions will generally comprise from about 0.01 to about 3.5 weight percent of 2,4,5,6-tetraaminopyrimidine and from about 0.01 to about 2.5 weight percent of 2,6-dihydroxypyridine. The molar ratio of primary intermediate to coupler will generally range from about 5:1 to about 1:5 and be employed in any suitable carrier or vehicle, generally an aqueous or hydroalcoholic solution, preferably an aqueous solution. The carrier or vehicle will generally comprise up to about 40 weight percent of the composition.
Optionally, the hair coloring system and compositions of this invention may also utilize a yellow direct dye or a known oxidative yellow dye. Any suitable yellow direct or known oxidative yellow dye may be employed and will preferably be selected to provide the yellow coloration desired. The rate of loss of hair coloration due to loss of the direct or known oxidative yellow dye will essentially match the increase in yellow coloration imparted by the oxidatively colored hair obtained by the hair coloring process and composition of this invention. Among the suitable yellow direct dyes that may be employed 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.
The preferred known oxidative yellow dyes that may be employed are selected from the group consisting of 6-amino-m-cresol, o-amino-phenol, and 2-amino-m-cresol.
According to a further aspect of this invention, one or more other primary intermediates and one or more other couplers may be employed in the hair coloring systems and compositions in addition to the 2,4,5,6-tetraaminopyrimidine and 2,6-dihydroxypyridine.
Suitable optional primary intermediates include, for example, p-phenylenediamine derivatives such as: 2-methyl-p-phenylenediamine, p-phenylenediamine, 2-chloro-p-phenylenediamine, N-phenyl-p-phenylenediamine, N-(2-methoxyethyl)-p-phenylenediamine, N,N-bis(2-hydroxyethyl)-p-phenylenediamine, 2-hydroxymethyl-p-phenylenediamine, 2-(1-hydroxyethyl)-p-phenylenediamine, 2-(2-hydroxyethyl)-p-phenylenediamine, 4,4'diamino-diphenylamine, 2,6-dimethyl-p-phenylenediamine, 2-isopropyl-p-phenylenediamine, N-(2-hydroxypropyl)-p-phenylene-diamine, 2-propyl-p-phenylenediamine, 1,3-bis[(N-hydroxyethyl)-N-(4-aminophenyl)-amino]-2-propanol, 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 such as: 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;
o-aminophenol derivatives such as: o-aminophenol, 2,4-diaminophenol, 5-methyl-2-aminophenol, 6-methyl-2-aminophenol, 2-ethylamino-p-cresol and 2-amino-5-acetaminophenol and 4-methyl-2-aminophenol; and heterocyclic derivatives such as: 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 primary intermediates can be employed in the form of a free base or in the form of an acid additive salt thereof, such as, for example, as a hydrochloride, a hydrobromide, a sulfate or the like.
Suitable optional additional couplers include, for example, phenols, resorcinol and naphthol derivatives such as: 1,7-dihydroxynaphthalene, resorcinol, 4-chlororesorcinol, 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;
m-phenylenediamines such as: m-phenylenediamine, 2,4-diamino-phenoxyethanol, N,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-methylphenetole, 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;
m-aminophenols such as: m-aminophenol, 2-hydroxy-4-(carbamoyl-methylamino)toluene, m-carbamoylmethylaminophenol, 6-hydroxybenzomorpholine, 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, N-hydroxyethyl-4-methoxy-6-methyl-m-aminophenol and 5-amino-4-methoxy-2-methylphenol; and heterocyclic derivatives such as: 1-phenyl-3-methyl-5-pyrazolone, 6-methoxy-8-aminoquinoline, 2,6-dihydroxy-4-methylpyridine, 5-hydroxy-1,4-benzodioxane, 3,4-methylenedioxyphenol, 4-(2-hydroxyethylamino)-1,2-methylene-dioxybenzene, 2,6-dihydroxy-3,4-dimethylpyridine, 5-chloro-2,3-dihydroxypyridine, 3,5-diamino-2,6-dimethoxypyridine, 3,4-methylene-dioxyaniline, 2,6-bis(2-hydroxyethoxy)-3,5-diaminopyridine, 4-hydroxyindole, 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 primary intermediates include:
p-phenylenediamine derivatives such as: 2-methyl-p-phenylenediamine, p-phenylenediamine, N-(2-methoxyethyl)-p-phenylenediamine, N,N-bis(2-hydroxyethyl)-p-phenylenediamine, 2-(1-hydroxyethyl)-p-phenylenediamine, 2-(2-hydroxyethyl)-p-phenylenediamine, and 2-(1,2-dihydroxyethyl)-p-phenylenediamine;
p-aminophenol derivatives such as: p-aminophenol, p-methylaminophenol, 3-methyl-4-aminophenol, 2-methoxymethyl-4-aminophenol and 1-(5-amino-2-hydroxy-phenyl)-ethane-1,2-diol;
o-aminophenol derivatives such as: o-aminophenol, 2-ethylamino-p-cresol, 5-methyl-2-aminophenol, 6-methyl-2-aminophenol and 2-amino-5-acetamino-phenol, 4-methyl-2-aminophenol; and heterocyclic derivatives such as: 4,5-diamino-1-methylpyrazole, 1-(2-hydroxyethyl)-4,5-diaminopyrazole, and 2-dimethyl-amino-5-aminopyridine.
Preferred optional additional couplers include:
phenols, resorcinol and naphthol derivatives such as: 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;
m-phenylenediamines such as: m-phenylenediamine, 2,4-diamino-phenoxyethanol, 1,3-bis(2,4-diaminophenoxy)propane, 2-amino-4-(2-hydroxyethyl-amino)anisole and 4,6-bis(2-hydroxyethoxy)-m-phenylenediamine, 3-(2,4-diamino-phenoxy)-1-propanol;
m-aminophenols such as: m-aminophenol, 6-hydroxybenzomorpholine, 2-hydroxy-4-aminotoluene, 2-hydroxy-4-(2-hydroxyethylamino)toluene and 2-methyl-m-aminophenol; and heterocyclic derivatives such as: 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-diamino-pyridine and 2-amino-3-hydroxypyridine.
Most preferred optional primary intermediates include:
p-phenylenediamine derivatives such as: 2-methyl-p-phenylenediamine, p-phenylenediamine, N,N-bis(2-hydroxyethyl)-p-phenylenediamine, 2-(1-hydroxyethyl)-p-phenylenediamine and 2-(2-hydroxyethyl)-p-phenylenediamine;
p-aminophenol derivatives such as: p-aminophenol, p-methylaminophenol, 3-methyl-4-aminophenol and 1-(5-amino-2-hydroxyphenyl)-ethane-1,2-diol;
o-amino derivatives such as: o-aminophenol, 2-ethylamino-p-cresol, 5-methyl-2-aminophenol, 6-methyl-2-aminophenol and 2-amino-5-acetaminophenol; and heterocyclic derivatives such as: 1-(2-hydroxyethyl)-4,5-diaminopyrazole.

Most preferred optional additional couplers include:
phenols, resorcinol and naphthol derivatives such as: 2-methyl-1 naphthol, 1-acetoxy-2-methylnaphthalene, resorcinol, 4-chlororesorcinol, 1 naphthol and 2-methylresorcinol;
m-phenylenediamines such as: 2,4-diaminophenoxyethanol, 2-amino 4-(2-hydroxyethylamino)anisole and 4,6-bis(2-hydroxyethoxy)-m phenylenediamine and 3-(2,4-diaminophenoxy)-1-propanol;
m-aminophenols such as: m-aminophenol, 6-hydroxybenzomorpholine, 2-hydroxy-4-aminotoluene, 2-hydroxy-4-(2-hydroxyethylamino)toluene and 2-methyl-m-aminophenol; and heterocyclic derivatives such as: 1-phenyl-3-methyl-5-pyrazolone, 2-amino-3-hydroxypyridine and 6-hydroxyindole.
The dye composition in this invention can be formulated in a lotion or in a cream or gel by including the appropriate types and amounts of surfactants, emulsifiers or polymers and alkalizing agents. The surfactants and emulsifiers can be anionic, cationic or nonionic, and they can be hydrophobic or hydrophilic. Examples of these surfactants and emulsifiers are: Sodium lauryl sulfate, ammonium lauryl sulfate, cetyl alcohol, cetearyl alcohol, oleic acid, dilinoeic acid, polyethylene glycols of various fatty alcohols, lauramide DEA, lauramide MEA, behenetrimonium chloride, cetrimonium 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 use on hair. At the end of the coloring period, which can range from 5 minutes to 40 minutes, the composition is washed from the hair with ordinary water rinse followed by a shampoo. Typical dye compositions are described in the following examples:
INGR_E_DIENTS ~ EXAMPLE 1 EXAMPLE 2 _~ E__X_AMPLE

Cocamidopropyl betaine7 Cetyl alcohol 7 5 Propylene glycol 15 3 Oleic acid 1 15 10 Octylpolyglycoside 5 Steareth-21 3 C12-15 Pareth-3 5 Ammonium hydroxide 5 10 7 Monoethanolamine 2 3 EDTA 0.1 0.1 0.1 Sodium sulfite 0.1 0.1 0.1 Fragrance 0.5 0.5 0.5 DYES:

2,4,5,6-tetraaminopyrimidine1.0 1.0 1.0 2,6 dihydroxypyridine1.0 1.0 1.0 Water qs to 100 qs to 100 qs to 100 ~

In the following examples untreated Piedmont hair was dyed with an oxidative dyeing composition of this invention and with comparative prior art compositions. For comparison purposes, dyeing results are presented for typical prior art oxidative dyeing compositions employed to produce yellow coloration, namely compositions employing o-aminophenol, as the primary intermediate, and 1-naphthol, 5-amino-o-cresol or resorcinol as couplers. The dyeing solution comprised the primary intermediate and coupler at 1 weight percent in 100 g of a typical common dye base.
The dyeing solution was mixed with an equal amount of 6% hydrogen peroxide. The resulting dyeing formulation was applied to the hair and permitted to remain in contact with the hair for 30 minutes. The dyed hair was then shampooed and rinsed with water and dried. After dyeing and after exposure to a fade-o-meter, an instrument that simulates sun exposure, coloration results were measured using a Minolta spectrophotometer Chroma Meter 3700d reflectometer. The Minolta Chroma Meter 3700d spectrophotometer uses reflected light from a surface and gives results in terms of the CIE (International Commission on Illumination) tristimulus values.
These values are subsequently transformed mathematically into the L* a* b*
color space, wherein the magnitude of changes in hue and intensity of color correspond closely with those perceived by the human eye.
L*, being achromatic, ranges from black (L*=0) to white (L*=100); this term is called "metric lightness" and is a measure of how light or dark a color is, relative to a matching shade of gray. Hue is measured in terms of the chromaticity coordinates a* and b*, where a* indicates redness (a*>0) and b*
indicates yellowness. (b*>0). The values of a* and b* can be plotted with a*
as the x-axis and b* as the y-axis to give quantitative color information:
"metric chroma" is the length of a line from the origin (a*=0, b*=0) to the point of a sample reading while metric hue angle is the angle between the a* axis and the metric chroma line. Metric chroma indicates the strength of a color response (i.e., the extent to which a color differs from its matching shade of gray). Metric hue angle quantifies hue in degrees, with larger values indicating more yellow hues and smaller values indicating more red (or less yellow) hues.
The results of the tests are set forth in the following Table 1 for the comparative compositions and in Table 2 for the composition of this invention.
The baseline average values of L*, a* and b* for undyed, untreated Piedmont hair were L* 72.32, a* 2.0, b* 23.2.

T~hln ~1 Comparative Dyeing Components L* a* b*

Example A 1-Naphthol/o-aminophenol 66.9 5.2 36.8 after 12 hr fade-o-meter 66.1 5.2 29.3 after 24 hr fade-o-meter 67.3 5.2 27.9 B 5-Amino-o-cresol/o-aminophenol64.9 9.6 34.9 after 12 hr fade-o-meter 64.0 8.3 29.5 after 24 hr fade-o-meter 65.5 7.6 27.8 C Resorcinol/o-aminophenol 63.2 4.4 36.5 after 12 hr fade-o-meter 65.1 3.1 30.1 after 24 hr fade-o-meter 67.1 2.0 26.5 Table 2 Example Dyeing Components L* a* b*

2,6-Dihydroxypyridine/

2,4,5,6-tetraaminopyrimidine 55.4 -1.5 20.5 after 1 day 58.1 0.5 37.5 after 4 days 61.2 1.1 44.9 after 5 days 63.2 0.6 45.2 after 10 days 63.8 1.6 48.1 after 10 days and subsequent 24 hour fade-o-meter 66.7 2.6 46.8 The spectrophotometer readings in Table 1 demonstrate the poor yellow coloring and poor light stability of the oxidatively dyed yellow coloring of the prior art. In contrast, the spectrophotometer readings in Table 2 demonstrate the increasing brightness of the yellow coloration of the composition of the invention over a period of ten days following dyeing, and the light stability of the coloration even after ten days and subsequent exposure to 24 hours of the fade-o-meter.
With the foregoing description of the invention, those skilled in the art will appreciate that modifications may be made to the invention without departing from the spirit thereof. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.

Claims

WE CLAIM:

1. A human hair dyeing composition for the oxidative dyeing of human hair comprising, in a suitable carrier or vehicle, a compound of the formula wherein R1 and R2 are independently H; C1-4 alkyl, optionally substituted with one or more hydroxy- or amino groups;
R1 and R2 may form a 5- or 6-membered heterocyclic ring optionally containing one additional N- or O- heteroatom in the ring as a primary intermediate and a compound of the formula wherein R1 and R2 are independently H; C1-4 alkyl or hydroxy-alkyl as a coupler and at least one oxidizing agent.

2. The composition according to Claim 1 further comprising a yellow direct dye or a known oxidative yellow dye.

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

6. The composition according to Claim 5 further comprising a yellow direct dye or a known oxidative dye.

7. The composition according to 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 according to 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 process for the oxidative dyeing of human hair a yellow color which comprises applying to the hair a hair-dyeing effective amount of a composition containing, in a suitable carrier or vehicle, a compound of the formula wherein R1 and R2 are independently H; C1-4 alkyl, optionally substituted with one or more hydroxy- or amino groups;
R1 and R2 may form a 5- or 6-membered heterocyclic ring optionally containing one additional N- or O- heteroatom in the ring as a primary intermediate and a compound of the formula wherein R1 and R2 are independently H; C1-4 alkyl or hydroxy-alkyl as a coupler and at least one oxidizing agent.

10. The process according to Claim 9 further comprising a yellow direct dye or a known oxidative yellow dye.

11. The process according to 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 process according to Claim 9 wherein the oxidative yellow dye is selected from the group consisting of 6-amino-m-cresol, o-amino-phenol, and 2-amino-m-cresol.

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

14. In an improved human hair dyeing composition for the oxidative dyeing of human hair wherein the improvement comprises a 2,4,5,6-tetraaminopyrimidine primary intermediate, a 2,6-dihydroxypyridine coupler and at least one oxidizing agent in a suitable carrier or vehicle.

15. The composition according to Claim 14 further comprising a yellow direct dye or a known oxidative yellow dye.

16. The composition according to Claim 15 wherein the yellow direct dye 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 according to 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.