Aminophenyl alkylenediamines useful in oxidation hair dyes
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to new aminophenyl alkylenediamines and salts thereof and to their use as developer components in oxidation hair dyes. 
     2. Statement of Related Art 
     By virtue of their intense colors and good fastness properties, oxidation hair dyes play a prominent part in the dyeing of hair. Hair dyes such as these contain oxidation dye precursors in a cosmetic carrier. Developer substances and coupler substances are used as the oxidation dye precursors. The developer components form the actual dyes with one another or by coupling with one or more coupler components under the effect of oxidizing agents or atmospheric oxygen. 
     Good oxidation dye precursors have to satisfy various requirements. They must form the required shades with sufficient intensity during the oxidative coupling reaction. They must be readily absorbed by human hair with no significant differences in this regard between neglected and freshly washed hair. They should be stable to light, heat and the effect of chemical reducing agents especially when in the form of liquid hair dye preparations. Finally, they should not excessively stain the scalp and, above all, should be toxicologically and dermatologically safe to use. 
     The developer substances conventionally used include primary aromatic amines containing another free or substituted hydroxy or amino moiety in the para or ortho position, diaminopyridine derivatives, heterocyclic hydrazine derivatives and 4-aminopyrazolone derivatives. Useful conventional coupler substances include m-phenylenediamine derivatives, naphthols, resorcinol derivatives and pyrazolones. 
     Particular importance is attributed to the intensity of the colors formed during the oxidative coupling reaction and to the fastness properties, more especially fastness to light. N,N&#39;-bix-(4-aminophenyl)-ethylenediamines are already known as oxidation dye precursors in hair dyes from U.S. Pat. No. 4,010,200. However, the hair colors obtainable with these developer components in conjunction with standard coupler comounds do not satisfy the stringent requirements of the industry in regard to intensity and fastness properties. 
     DESCRIPTION OF THE INVENTION 
     Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term &#34;about&#34;. 
     It has now been found that considerably more intensive hair colors can be obtained by using N-4-aminophenyl-N&#39;-2,4-diaminophenyl alkylenediamines as a developer component. 
     The present invention also provides novel N-4-aminophenyl-N&#39;-2,4-diaminophenyl alkylenediamines, per se, corresponding to the formula: ##STR2## wherein: R 1  is --C n  H 2n  --, where n is 2 to 4, or ##STR3## and water soluble salts thereof. Among the compounds corresponding to this formula, N-4-aminophenyl-N&#39;-2,4-diaminophenyl ethylenediamine is the most important. 
     The new compounds corresponding to formula (I) may be prepared by a basically standard process in which N-(p-nitrophenyl)-alkylendediamines corresponding to the formula: ##STR4## wherein R 1  is as defined for formula I, are reacted with 2,4-dinitrofluorobenzene and the N-4-nitrophenyl-N&#39;-2,4-dinitrophenyl alkyenediamine obtained is catalytically hydrogenated to the N-4-aminophenyl-N&#39;-2,4-diaminophenyl alkylenediamine corresponding to formula (I). 
     The new compounds corresponding to formula (I) or salts thereof either alone or in mixtures are suitable for use as oxidation dye precursors of the developer type in hair dyes. They are capable of forming dyes under the effect of oxidizing agents alone. However, particularly intensive and brilliant dyes are formed by oxidative coupling in the presence of useful conventional coupler components. 
     The present invention also relates to hair dyes containing oxidation dye precursors in a cosmetic carrier, which contain as oxidation dye precursors N-4-aminophenyl-N&#39;-2,4-diaminophenyl alkylenediamines of formula (I) or water soluble salts thereof as a developer component in addition to conventional developer and coupler components and, optionally, substantive hair dyes. Among the many known conventional coupler substances, those containing phenolic hydroxyl moleties and those of the bis-(2,4-diaminophenyl)-alkane type and the bis-(2,4-diaminophenoxy)- alkane type, as described in U.S. Pat. No. 4,629,466 and in German patent document No. 28 52 272, are particularly suitable for combination with the new developers corresponding to formula (I). Accordingly, another particularly preferred embodiment of the invention comprises oxidative hair dyes containing phenols, naphthols, resorcinols and/or 1,3-bis-(2,4-diaminophenyl-alkanes or 1,3-bis-(2,4-diaminophenoxyl)-alkanes as a coupler component. Hair dyes such as these give particularly intensive and desirable colors in shades of blue-red, violet, blue and black. 
     The N-4-aminophenyl-N&#39;-2,4-diaminophenyl alkylenediamines corresponding to formula (I) may be isolated and used in hair dyes either as such or in the form of their water soluble salts with inorganic or organic acids, for example as hydrochlorides, sulfates, phosphates, acetates, propionates, lactates or citrates. 
     The developer substances and the coupler substances are generally used in equimolar quantities in the hair dyes according to the invention, although a certain excess of individual oxidation dye precursors is not a disadvantage, so that developer substances and coupler substances may be used in a mol ratio of 1.0:0.5-2.0. The N-4-aminophenyl-N&#39;-2,4-diaminophenyl alkylenediamines corresponding to formula (I) according to the invention or salts thereof may be used in a quantity of from 0.05-10 millimols per 100 g hair dye. The compounds corresponding to formula (I) do not have to be used as individual compounds. Instead, mixtures of the compounds may also be used. 
     Known substantive hair dyes, for example nitrophenylenediamine derivatives, anthraquinone dyes or indophenols, may also be added to the hair dyes according to the invention to modify the hair color. 
     To produce the hair dyes according to the invention, the oxidation dye precursors and, optionally, substantive dyes are incorporated in a suitable cosmetic carrier. Examples of suitable cosmetic carriers are creams, emulsions, gels, surfactant-containing foaming solutions, such as shampoos, or other preparations which are suitable for application to the hair. Standard ingredients of cosmetic preparations such as these include wetting agents and emulsifiers, such as anionic, nonionic or ampholytic surfactants, for example fatty alcohol sulfates, alkane sulfonates, alpha-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 thickeners, such as methyl or hydroxyethyl cellulose, starch, fatty alcohols, paraffin oils, fatty acids, perfume oils, and hair-care additives, such as water soluble cationic polymers, protein derivatives, pantothenic acid and cholesterol. 
     The ingredients of the cosmetic carriers are used in conventional quantities in the production of the hair dyes according to the invention. For example, the emulsifiers are used in concentrations of from 0.5 to 30% by weight and the thickeners in concentrations of from 0.1 to 25% by weight, based on the dye as a whole. The oxidation dye precursors (developers and couplers) are incorporated in the carrier minimally in hair-dye effective amounts, preferably in quantities of 0.2 to 5% by weight, most preferably 1 to 3% by weight, based on the dye as a whole. 
     One preferred formulation for the N-4-aminophenyl-N&#39;-2,4-diaminophenyl alkylenediamines corresponding to formula (I) comprises cream hair dyes in the form of an oil-in-water emulsion containing 
     (a) from 1 to 10 millimols per 100 g of inventive developer components, optionally mixed with conventional developer components, 
     (b) from 1 to 10 millimols per 100 g of conventional coupler components. 
     (c) from 1 to 10% by weight of a C 10-16  alkyl sulfate or C 10-16  alkyl ether sulfate surfactant, 
     (d) from 5 to 20% by weight of a C 12-18  fatty alcohol or C 12-18  fatty alcohol mixture, 
     (e) from 01. to 2.0% by weight of at least one oxidation inhibitor, preferably alkali sulfite, alkali ascorbate or alkali dithionite, 
     (f) ammonia q.s. to adjust the pH of the emulsion to between 8 and 10, and 
     (g) water q.s. to 100% 
     The alkyl sulfate or alkyl ether sulfate surfactant mentioned may be present as an alkali, ammonium or C 2-3  alkanolammonium salt for example as the sodium, triethanolammonium or isopropanolammonium salt. A sulfuric acid monoester salt of an adduct of 1 to 10 mols ethylene oxide with a C 10-16  fatty alcohol may be used as the alkyl (C 10-16 ) ether sulfate surfactant. 
     Basically, the hair color may be oxidatively developed with atmospheric oxygen. However, it is preferred to use a chemical oxidizing agent, particularly when it is desired not only to color, but also to lighten the hair. Particularly suitable oxidizing agents are hydrogen peroxide or adducts thereof with urea, melamine or sodium borate and also mixtures of such hydrogen peroxide adducts with potassium peroxydisulfate, present in an oxidizing effective amount. 
     The hair dyes according to the invention may be used in a mildly acidic, neutral or alkaline medium, irrespective of the type of cosmetic preparation used, for example a cream, gel or shampoo. The hair dyes are preferably used in the pH range from 8 to 10. They may be used at temperatures of from 15° C./ to 40° C. 
     After a contact time with the hair of 25-35 minutes, preferably about 30 minutes, the hair dye is removed by rinsing. The hair may then be washed with a mild shampoo and dried. Washing with a shampoo is unnecessary when a carrier of high surfactant content, for example a dye shampoo, is used. 
     The following Examples are intended to illustrate the invention without limiting it in any way. 
    
    
     EXAMPLES 
     1. Preparation Examples 
     N-4-aminophenyl-N&#39;-2,4-diaminophenyl ethylenediamine.5 HCl.H 2  O 
     [1.1]N-4-nitrophenyl-N&#39;-2,4-dinitrophenyl ethylenediamine 
     A mixture of 9.05 g (0.05 mol) N-(p-nitrophenyl)-ethylenediamine, 4.2 g (0.05 mol) sodium hydrogen carbonate and 100 ml ethanol was heated to 50° C. 9.3 g (0.05 mol) 2,4-dinitrofluorobenzene were added dropwise at that temperature. After boiling under reflux for 2 hours, the mixture was cooled and the deposit filtered off. Yellow crystals melting at 242° C. were obtained. 
     [1.2]N-4-aminophenyl-N&#39;-2,4-diaminophenyl ethylenediamine.5HCl.H 2  O 
     7 g of the reaction product from 1.1 were dissolved in 200 ml ethanol and hydrogenated at approximately 20° C./2 bar H 2  pressure in the presence of 0.5 g palladium on carbon. After hydrogen was complete, the catalyst was filtered and the filtrate (product) was acidified with hydrochloric acid and concentrated by evaporation to dryness. Violet crystals melting at 226° C. (with decomposition) were obtained. 
     2. Application Examples 
     Hair dyes according to the invention were prepared in the form of a hair dye cream emulsion having the following composition: 
     
         ______________________________________                                    
C.sub.12-14 fatty alcohol                                                 
                       10.0      g                                        
C.sub.12-14 fatty alcohol + 2 E.O sulfate,                                
                       25.0      g                                        
Na salt, 28%                                                              
Water                  60.0      g                                        
N--4-aminophenyl-N&#39;--2,4-diaminophenyl                                    
                       7.5       mmol                                     
ethylenediamine.5 HCl.H.sub.2 O                                           
Coupler component      7.5       mmol                                     
N.sub.2 SO.sub.3 (inhibitor)                                              
                       1.0       g                                        
Concentrated ammonia solution                                             
                       to pH 9.5                                          
Water                  q.s. to 100                                        
                                 g                                        
______________________________________                                    
 
    
     The constituents were mixed together in the above order. After addition of the oxidation dye precursors and the inhibitor, the pH of the emulsion was first adjusted to 9.5 with concentrated ammonia solution, after which the emulsion was made up with water to 100 g. 
     The hair color was oxidatively developed with 3% hydrogen peroxide solution as oxidizing agent. To this end, 50 g hydrogen peroxide solution (3%) were added and mixed with 100 g of the emulsion. 
     The dye cream was applied to approximately 5 cm long strands of standardized, 90% gray, but not specially pretreated human hair and left thereon for 30 minutes at 27° C. After dyeing, the hair was rinsed, washed with a standard shampoo and then dried. 
     The compounds shown in Table I were used as couplers in combination with the developer of Example I. The hair colors likewise shown in Table I were obtained. 
     The hair colors according to Examples 2.1 to 2.3 were additionally tested for fastness to light. 
     Testing of light fastness: 
     The fastness to light of the dyed hair strands was determined in accordance with DIN (German Industrial Norm) 54,004 (April 1966), Section 7.5.2 the method essentially comprises exposing the dyed hair strands alongside fabric samples with 6 fastness-graduated blue standard dyes of the fastness scale to the light of a xenon arc lamp with a color temperature of 5500 to 6500 °K. To this end, the strands and the fabric samples are fastened alongside one another to a card and the marginal zones of the strands and fabric samples are covered parallel to the longitudinal edge of the sample holder. Exposure is carried out with frequent inspection by removal of the cover plate until standard 3 of the light fastness scale shows a just noticeable difference between the exposed part of the unexposed part. The samples are then inspected for changes and the changes, if any, are evaluated by comparison with the changes in standards 1, 2 and 3 of the fastness scale. Exposure is then continued until standard 4 of the light fastness scale also shows a just noticeable difference in color between the exposed part and the unexposed part. The cover plate is then replaced by a larger cover plate which covers approximately 1/3 of the previously exposed surface parallel to the longitudinal edge. Exposure is then continued until standard 6 of the scale shows a just noticeable color difference. Light fastness is determined by comparing the contrasts on the stands of hair with the contrasts of the standard colors of the light fastness scale. 
     The result of the light fastness test are also shown in Table I. 
     
                       TABLE I                                                     
______________________________________                                    
Example                   Color                                           
No.     Coupler component obtained   Fastness                             
______________________________________                                    
2.1     1-naphthol        dark ruby  4                                    
2.2     resorcinol        brown-olive                                     
                                     4                                    
2.3     m-aminophenol     black      4                                    
2.4     5-amino-2-methylphenol                                            
                          dark violet                                     
2.5     5-amino-4-chloro-2-                                               
                          black violet                                    
        methylphenol                                                      
2.6     2,4-dichloro-3-aminophenol                                        
                          black                                           
2.7     1,3-bis-(2,4-diaminophenyl)-                                      
                          blue black                                      
        propane                                                           
______________________________________                                    
 
    
     All of the above obtained colors are considered desirable for hair dye purposes. Similarly the light fastness value of 4 indicates a hair dye whose light fastness is desirable for hair dye purposes.