Abstract:
1,3-disubstitued nitrobenzenes of the general formula I: ##STR1## in which X is a hydroxyl group or an amino group and R 1  is hydrogen or a C 1-4  alkyl group and their salts are suitable for use as an oxidation dye precursor of the coupler type, together with prior art primary intermediate components, for the production of oxidation dyes, preferably for the production of hair colorants. With developers of the p-phenylenediamine, p-aminophenol, 2.5-diaminopyridine, and 2,4,5,6-tetraaminopyrimidine types, primarily brown hues with great light stability are formed.

Description:
FIELD OF THE INVENTION 
     This invention relates to the use of 1,3-disubstituted 2-nitrobenzenes for the production of oxidation dyes, more particularly for the production of hair dyes. 
     STATE OF THE INVENTION 
     Oxidation dyes contain oxidation dye precursors in a suitable carrier. The oxidation dye precursors used are primary intermediate compounds which form intensive colors by oxidative coupling with one another or with one or more color modifiers in the presence of atmospheric oxygen. Suitable primary intermediate compounds are, for example, primary aromatic amines containing another free or substituted hydroxy or amino group in the para position or ortho position and also diaminopyridines, heterocyclic hydrazone derivatives, 4-aminopyrazolone derivatives and tetraaminopyrimidines. 
     The dyes obtainable by coupling of the primary intermediate components with one another are generally unsatisfactory. However, colors of high intensity and brilliance can often be obtained by coupling with phenols or aromatic amines. 
     Suitable color modifiers are, for example, m-phenylene diamines, m-aminophenols, resorcinols, naphthols and pyrazolones. 
     One of the most important applications of oxidation dyes is in the coloring of hair. Good oxidation hair dye precursors have to satisfy above all the following requirements: they must produce the required tints in sufficient intensity in the oxidative coupling reaction. In addition, they must be readily absorbable by human hair without excessively staining the scalp. In addition, the dye should be absorbed uniformly, i.e. the more seriously damaged hair ends should not be colored to a greater extent than the less damaged hair roots. The colors produced should show high stability to heat, light and the chemicals used for permanent waving. Finally, the oxidation hair dye precursors should be toxicologically and dermatologically safe. 
     Although nitrophenols and nitroanilines have certain coloring properties for keratin fibers, they are not normally suitable as color modifiers because the nitro group deactivates the aromatic core for the coupling reaction. The use of resorcinol as a color modifier is known from DEPSS 162 625 and 276 761. However, the light stability properties of oxidation hair colors obtainable with resorcinol are only moderate. m-Phenylenediamine and m-tolylenediamine have also long been used as color modifiers. 
     DESCRIPTION OF THE INVENTION 
     However, these color modifiers do not provide natural brown tones with the usual primary intermediate components. 
     SUMMARY OF THE INVENTION 
     It has now been found that 1,3-disubstituted nitrobenzenes corresponding to general formula I: ##STR2## in which X is a hydroxyl group or an amino group and R 1  is hydrogen or a C 1-4  alkyl group, and salts thereof are suitable as color modifiers together with known primary intermediate compounds for producing intensive oxidation colors. 
     The oxidation colors obtainable in this way are readily absorbed by hair and other keratin fibers and show high stability to light and heat. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Accordingly, the present invention also relates to hair dyes containing oxidation dye precursors in a carrier, 1,3-disubstituted nitrobenzenes corresponding to formula I or salts thereof as color modifiers and one or more primary intermediate components typically encountered in oxidation dyes being present as the oxidation dye precursors. 
     The 1,3-disubstituted nitrobenzenes corresponding to general formula I are compounds known from the literature or may be synthesized by methods known from the literature. 2-Nitroresorcinol is described, for example, in J. Org. Chem. 16 (1951), 611 while 2-nitro-m-phenylene diamine is described in J. Chem. Soc. Perkin Trans. I (1988), 1940-1941. They are suitable as color modifiers for a number of known primary intermediate compounds and produce intensive colors in the form of brown tones. Suitable primary intermediate components are, for example, aromatic amines or phenols containing one or more other NH 2  groups, NHR groups or NR 2  groups (R=C 1-4  alkyl) in the para or ortho position, an optionally substituted hydroxyalkyl or aminoalkyl group containing 2 to 4 carbon atoms, o- and p-aminophenol ethers, diaminopyridines, heterocyclic hydrazone derivatives such as for example, 1-methyl-2-pyrrolidone hydrazone, aminopyrazolone derivatives, such as 4-amino-1-phenyl-3-carbamoyl-5-pyrazolone, 2,4,5,6-tetraaminopyrimidine and N-substituted derivatives thereof and 4-hydroxy-2,5,6-tetraaminopyrimidines. Examples of particularly suitable primary intermediate components are given in the following as components D1-D10. 
     In the hair dyes according to the invention, the compounds corresponding to formula I may be used either in free form or also in the form of a salt. 2-Nitroresorcinols form salts with bases. Suitable salts are, for example, the alkali metal, ammonium, mono-, di- and tri-alkanolammonium salts containing 2 to 4 carbon atoms in the alkanol group or even the magnesium or calcium salt. 2-Nitro-m-phenylenediamines form salts with acids. Suitable salts are, for example, the hydrochlorides, sulfates, phosphates, acetates, propionates, lactates or citrates. 
     In addition to the 1,3-disubstituted nitrobenzenes corresponding to formula I, the hair dyes according to the invention may also contain other known color modifiers necessary for modifying the tints and for producing naturallooking tones. Known color modifiers of the type in question are, for example, m-phenylenediamines, 2,4-diaminophenol ethers, bis-(2,4-diaminophenoxy)-alkanes, o- and m-cresol, resorcinol, hydroquinone, pyrogallol, pyrocatechol, α-naphthol, 1,5- or 1,7-dihydroxynaphthalene, 1-phenyl-3-methyl-5-pyrazolone, 1-phenyl-3-amino-5-pyrazolone, 1phenyl-3,5-diketopyrazolidine, 1-methyl-7-dimethylamino-4-hydroxy-2-quinolone or imidazo[1,2a]pyridin-2(3H)-ones. 
     The 1,3-disubstituted nitrobenzenes corresponding to formula I and the color modifiers additionally used, if any, are generally added to the hair dyes according to the invention in substantially molar quantities, based on the primary intermediate components used. Although it has proved useful to employ molar quantities, there is no disadvantage in using a certain excess of individual oxidation dye precursors so that primary intermediate components and color modifiers may be present in a molar ratio of 1:0.5 to 1:2. 
     The oxidation dye precursors or substantive dyes otherwise present in the hair dyes do not have to be individual chemical compounds. On the contrary, they may also be mixtures of the modifier and primary intermediate components to be used in accordance with the invention. 
     To produce the hair dyes according to the invention, the oxidation dye precursors are incorporated in a suitable cosmetic carrier. Such carriers are, for example, creams, emulsions, gels or even surfactant-containing foaming solutions, for example shampoos or other preparations suitable for application to the hair. Typical constituents of such cosmetic preparations are, for example, wetting agents and emulsifiers, such as anionic, nonionic, ampholytic or zwitterionic surfactants, for example soaps, fatty alcohol sulfates, alkanesulfonates, α-olefin sulfonates, fatty alcohol polyglycol ether sulfates, ethylene oxide adducts with fatty alcohols, fatty acids and alkylphenols, sorbitan fatty acid esters and fatty acid partial glycerides, fatty acid alkanolamides and also thickeners such as, for example, methyl or hydroxyethyl cellulose, starch, fatty components such as, for example, fatty alcohols, paraffin oils or fatty acid esters, perfume oils and hair-care additives such as, for example, water-soluble cationic polymers, protein derivatives, pantothenic acid and cholesterol. 
     A particularly suitable carrier is a gel containing 1 to 20% by weight of a soap, preferably ammonium oleate, or s an oil-in-water emulsion containing 1 to 25% by weight of a fatty component and 0.5 to 30% by weight of an emulsifier from the group consisting of anionic, nonionic, ampholytic or zwitterionic surfactants. 
     The oxidation dye precursors are incorporated in the carrier in quantities of 0.2 to 5% by weight and preferably in quantities of 1 to 3% by weight, based on the dye as a whole. The content of 2-nitroresorcinol in the hair dyes according to the invention may be between about 0.05 and 10 millimoles per 100 g of the hair dye. 
     Basically, the color can be oxidatively developed with atmospheric oxygen. However, it is preferred to use a chemical oxidizing agent, particularly when the hair is to be both colored and lightened. Particularly suitable oxidizing agents are hydrogen peroxide or adducts thereof with urea, melamine, or sodium borate and mixtures of such hydrogen peroxide adducts with potassium peroxydisulfate. 
     A preparation of the oxidizing agent is preferably mixed with the preparation of oxidation dye precursors and carrier immediately before coloring of the hair. The ready-to-use hair-coloring preparation formed should preferably have a pH value of 6 to 10. 
     In a particularly preferred embodiment, the hair dyes are applied in a mildly alkaline medium. The application temperatures may be in the range from 15° C. to 40° C. After a contact time of about 30 minutes, the hair dye is removed from the hair to be colored by rinsing. The hair is then washed with a mild shampoo and dried. There is no need for washing with a shampoo in cases where a carrier of high surfactant content, for example a coloring shampoo, has been used. 
     The following Examples are intended to illustrate the invention without limiting it in any way. 
     EXAMPLES 
     Hair dyes according to the invention were prepared in the form of a hair-dyeing cream emulsion having the following composition: 
     
         ______________________________________C.sub.12-18 fatty alcohol                   10     gC.sub.12-14 fatty alcohol + 2EO sulfate,                   25     gNa salt, 28%Water                   60     gPrimary intermediate (component D1-D10)                   7.5    mmoleColor modifier (component M1, M2)                   7.5    mmoleNa.sub.2 SO.sub.3 (inhibitor)                   1.0    gConcentrated ammonia solution                   to pH 9.5Water                   ad 100 g______________________________________ 
    
     The constituents were mixed together in this order. After addition of the oxidation dye precursors and the inhibitor, the emulsion was first adjusted to pH 9.5 with concentrated ammonia solution and then made up with water to 100 g. 
     The color was oxidatively developed with 3% hydrogen peroxide solution as oxidizing agent. To this end, 50 g of hydrogen peroxide solution (3%) were added to and mixed with 100 g of the emulsion. 
     The dyeing cream was applied to about 5 cm long strands of standardized, 90% grey, but not specially pretreated human hair and left thereon for 30 minutes at 27° C. After dyeing, the hair was rinsed, washed with a normal shampoo and subsequently dried. 
     The following compounds were used as the primary intermediate components (components D1-D10): 
     D1: p-phenylenediamine 
     D2: p-tolylenediamine 
     D3: 2-chloro-p-phenylenediamine 
     D4: N-methyl-p-phenylenediamine 
     D5: N-(2-methoxyethyl)-p-phenylenediamine 
     D6: N,N-bis-(2-hydroxyethyl)-p-phenylenediamine 
     D7: p-aminophenol 
     D8: 2,5-diaminopyridine 
     D9: 1-phenyl-3-carboxyamido-4-amino-5-pyrazolone 
     D10: 2,4,5,6-tetraaminopyrimidine. 
     The following color modifiers were used: 
     M1: 2-nitroresorcinol 
     M2: 2-nitro-m-phenylenediamine. 
     The hair colors obtained are listed in the following Table: 
     
         ______________________________________Hair dyeexample   Primary  intermediate  Modifier Tint______________________________________1         D1       M1            Dark brown2         D2       M1            Brown3         D3       M1            Dark brown4         D4       M1            Dark violet5         D5       M1            Dark violet6         D6       M1            Dark violet7         D7       M1            medium brown8         D8       M1            Deer-brown9         D9       M1            Grey-magenta10         D10     M1            Yellow-brown11        D2       M2            Brown-violet12         D10     M2            Red-brown______________________________________