NZ247492A - Dye composition (for hair) comprising an aqueous solution of sodium chlorite and a dihydroxy indole (melanin precursor) - Google Patents

Description

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P.O. ..•• -■ r. ■ I - r NO DRAWINGS NEW ZEALAND / ? . , /' * PATENTS ACT, 1953 , U • .A § , M No.: >995 Date: V V COMPLETE SPECIFICATION COMPOSITION AND METHOD FOR DYEING HAIR WITH INDOI.IC COMPOUNDS IN THE PRESENCE OF A CHLORITE OXIDANT We, BRISTOI^MYERS SQUIBB COMPANY a corporation organized and existing under the laws of the State of Delaware, United States of America, of 345 Park Avenue, New York, New York 10154, United States of America, hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- - 1 -(followed by page la) 24749 This .r.vent:::. ::r,cerr.: r.ethcds ana compositions ::r ayeir.c: ".uzar. r.air.

BACKGROUND CF THE I^/ENTICN Moaern hair i/eir.q methodology has developed from its initiation in the 1350s to the point where today it is the third largest product type in the hair care category, following shampccs and conditioners.

One widely employed method for dyeing hair is based upon the production cf the r.atura* pigment oeianm. The exact structure :: r.eianm it not >:nown. It is a polymer produced from tyrosine 'ov a series of metabolic reactions the exact course of which remains to be clarified. To take advantage of what has been elucidated with respect to the formation cf melanin, it has become the practice of the art to utilize 5,6-dihydroxyindole DHI) cr 5,6-dihydroxyindole-2-carfcoxylie (DHICA) as the dyeing igent. These compounds have been clearly established as intermediates in the pathway leading to the production of meianm. -1a- There are a r.unxer :: prociems associated with the use cf DHI. It is difficult ana expensive to synthesize ana is extremely unstable m air. It rapidly decomposes in air to form other materials which are ineffective as hair colorants.

Diacetoxyindole (DAI) is used by the art in its attempts to avoid these problems with DHI. The practice has been to package DAI under mildly alkaline conditions in packages designed to protect the ingredients from air. Over the course of the time, between the initial packaging and the final use, the DAI is hydrolyzed to DHI. Since it is protected from air by the packaging, the DHI remains stable until it is ready for use.

It is known that use of DHI alone requires a long dyeout time. Therefore a variety of accelerators has been employed to hasten the dye formation. Oxidants, such as hydrogen peroxide, are the most widely employed of the various accelerators which have been proposed.

The use of oxidants has not been particularly successful with DHI, because oxidation takes place before the DHI penetrates the hair. Ideally, the DHI should penetrate the hair before oxidation takes place so that the pigment forms within the hair fiber. When the colorant forms in this manner, the color does not easily wash out. In contrast, if oxidation and melanin formation take place m tr.e solution there is little or no dyeing effect. If oxidation taKes place on the surface of the nair, the coloring is easily vasned away during shampooing.

In attempts to avoid these problems, the art has adopted a two step process. DHI is applied first and allowed to penetrate into the hair. The oxidant is applied in a second step. This procedure is described, for example, in US 2,934,396. Such procedures are lengthy and inconvenient.

It is one object of this invention to provide a one-step dyeing procedure, that is, a method, in which DHI and oxidant are applied to the hair simultaneously.

Dyeing with DHI is very attractive to many consumers, since its conversion to melanin is close to the natural pigmentation process. However, there are disadvantages. One such disadvantage is that, while natural hair color comes in an inexhaustible variety of shades, many oxidants which are used in combination with DHI dye the hair only to a gray or black color with little or no warmth. Extensive research efforts have been undertaken to find ways to modify the final color result after dyeing with DHI.

One way to cbtam a crown tonality is througn use of hvarogen peroxide. In tnis procedure, the hair is first dyed clack through formation of melanin and then partially fcleacnea to crown through destruction cf part of the melanin. A clear disadvantage is the waste of DHI, which is supplied at the beginning. This is important, because DHI is an expensive raw material, and will control the price of the final product.

A second disadvantage is the fact that uneven and unpredictable results are crten obtained due to the heterogeneity cf living hair and the difference in its affinities for the dye, which vary from one person to another.

A third disadvantage is the likelihood of oxidative damage to the keratin of the hair as a result of the use of a product, containing peroxide - noticeable in a coarse feel of the hair. Moreover, hydrogen peroxide is normally used under alkaline jonaitions, with ammonia or an amine as the alkaline reagent. These alkaline reagents impart strong odors to the hair dyeing compositions and are unacceptable to many users.

A fourth disadvantage is that peroxide attacks and partly destroys the natural hair pigment. This weakens the hair and changes its feel and appearance. -?'j f . 'V Vr, For tr.ese reasons, -any efforts have ceen undertaken :r. the art to avoid the problems connected with the use of hydrogen peroxide.

It is, therefore, another object of the invention to provide a method to dye hair to a dark brown shade without using hydrogen peroxide.

Comparison with prior art As described above, US 2,934,396 teaches that dyeing with DHI requires two steps.

CJS 3,236,734 teaches dyeing with l-(alkylamino)-2,4-dihydroxy benzene and an oxidant in one or two steps. Chlorites, but not sodium chlorite specifically, are mentioned among the oxidants said to be useful, but according to the teaching of this patent, all oxidants work equally well with the specified substrate, l-(alkylamino)-2,4-dihydroxy benzene. This is clearly not the case, when DHI is used, as will be demonstrated later in the examples (Example 1). 2 4/4 It snouid be ur.aerstcoa, that under the heading "peroxide*, there sight also ce compounds, wnicn produce peroxide after being dissolved in water; ::r example, perborate, percarbonate, urea peroxide and the like.

As will be shown m the examples, at a given concentration of CHI and with egual dyeing time, sodium chlorite gives the darkest coloration on hair, and provides the most economic use of the DHI.

US 3,194,734 teaches the use of a variety of oxidizing agents with DHI or with l-,2- or 3- methyl substituted DHI derivatives in alkaline media in a one- or two-step process to color hair. Sodium chlorite is not mentioned in the patent.

As will be seen in the examples (Example 3), among all the oxidants, which are listed in the patent, only peroxide gives useful results in a one-step dyeing process with DHI. Moreover, :n order to obtain dark dyeings at a relatively low concentration of DHI, the presence of a substantial amount of ammonia is reguired. As stated above, this causes unacceptable odor problems.

US 5,032,138 teaches dyeing with standard oxidation dyes (primary intermediates and couplers) in combination with chlorite. Melanin precursors are not included in the patent. .a 2 . 3 4 4 ,8 69 teacr.es eyeing of hair with o-aipnenois and an :xidant, selected from aaaoniun and aikali metal iodates, renoaates cr persuifates. However, these oxidants, when used in s cr.e-step treatment with DHI, give only weak colors on hair, since most of the DHI is oxidized and polymerized in solution, cefcre it can penetrate the hair.

The art has long sought a suitable oxidizing agent which can oe employed without the problems discussed above. More specifically, the art has souqnt aye compositions which will produce melanin in hair and give the hair a desirable color, with lasting wear qualities, in shorter periods of time, while avoiding the use of hydrogen peroxide and its resulting oxidative and bleaching damage to the hair.

SUMMARY OF THE INVENTION Oxidative hair dyeing compositions and methods for their use have now been discovered which avoid many of the problems of prior art compositions. These novel compositions are characterized by the use cf sodium chlorite as the oxidizing agent. The use of sodium chlorite, with 5,6-dihydroxyindoline, DHI or selected analogs, homologs or derivatives thereof, or with these compounds together with oxidizable primary intermediates and couplers, or together with DHICA or its lower alkyl esters, for example methyl to hexyl esters including straight chain and . i", r^' 4 * e , f 4 ' -■ ' SL. ^rancr.ea : r. a 1 r. ./.y I ••stirrs r:as net reen s zee it i c a i 1 y tauant cr suggested by any or the .'.oove citations nor, so far as the .nventors are aware, :.y any ether prior art.

DHI and DHI derivatives, analogs and homologs which may be •mpioyed in the practice of this invention include melanin rorming compounds represented by the formula: ..■herein R represents hydrogen, alkyl, hydroxyalkyl, aminoalkyl, each alkyl group containing up to eight carbon atoms; aryl or substituted aryl containing up to three reaction inert ;ubstituents; R represents hydrogen or alkyl containing up to six arbon atoms; and mixtures of said compounds. The compound 5,6-iihydroxyindoline is also useful in this invention because under the conditions employed, it is oxidized to dopaminochrorae which redrrnnges to DHI. The DHI then converts to melanin in iccordance with the invention. a 9 I'he prererrea N-sucsritutea cccpounds cr the present invention are those or structure I where the N-substituent, P, is nyarogen, alkyl, hydroxyalkyl, ammoalkyl, containing 1 to 3 carbon atoms in the noiety or a substituted or unsubstituted aryl wherein aryl substituents are reaction inert substituents such as OH, NH^, alkyl, alkoxyl, or N02- The most preferred compound is DHI.

For convenience, the invention will hereinafter be described principally with reference to DHI, but it should be remembered that the invention is applicable to all of the compounds within the scope of the above generic formula and their equivalents. I'he various compounds may be used alone or in numerous mixtures, including mixtures with other oxidative dyes or with DHICA or its lower alkyl esters, to achieve a variety of shades and tonal qualities with hair fibers.

It is most unexpected to find that this specific oxidizing agent will accelerate the formation of melanin, but not to such an extent that DHI is oxidized appreciably before it is distributed in the hair fiber.

It is equally surprising and unexpected to find that sodium chlorite imparts a dark brown color of natural appearance to the hair at relatively low concentrations of DHI and without the use of ammonia or other amines. 9 2 4 7 4 9 v A further surprisma aspect cr the invention is tr.e finding that DHICA and its lower alkyl esters or oxidizaole primary intermediates and couplers can ce employed in association with sodium chlorite and DHI to achieve a wider variety of tonalities m the treated hair.

There are many advantages to the compositions and methods of the invention. These include: Melanin is formed m the hair, imparting a brown color of natural appearance with relatively low concentrations of DHI. These low concentrations are possible, because none of the melanin, which was already present in the fiber, or is formed during dyeing, is destroyed. This results is cost savings for the manufacturer as well as for the consumer. 2. Melanin is deposited in a predictable and reproducible way. Dyeing results are even and appealing. 3. The dyeing procedure is simple (one-step) and fast. 4. Sodium chlorite does not cause oxidative damage to human hair or to the natural- hair pigment, as does hydrogen peroxide. -10 . The wear quality c: the c appreciably enhanced i.e. the a longer period of time. oiors produced ir. the dyed hair original dyed color is retained is for 6. The actual coloring of the hair can be performed at a pH which is at, or close to, neutrality.

The odor may be markedly reduced because ammonia or amines are omitted from the compositions.

DETAILED DESCRIPTION OF THE INVENTION The compositions of this invention as applied to human hair, either living or in a wig or other artificial device with implanted human hair, comprise an agueous vehicle which may contain a water miscible solvent, such as a lower alkanol, typically ethanol or isopropanol to aid solubility, together with DH3, or other compound(s) of the class defined above. Other compositions of the invention may contain DHI and/or a derivative, analog or homolog together with DHICA or lower alkyl ester, or a primary intermediate/coupler combination. Of course, if such combination is employed, it may contain more than one •. nternediate or coupler to achieve a variety of shades.

A typical aqueous composition of the invention as applied to the hair may contain from substantially 0.1% to 3%, preferably 0.3% to 1.')% 1)1(1 or DHI analog, homolog or derivative, and from substantially -11- ( l •* \ • 1! t .. \ , prereraciy . t t~ 44 or soaiuz cr.lonte. It is .'onera; ;y prererrea tc eaplcy lower concentrations of the xiai2ir;a agent vnen the concentration of DHI utilized is at the aw f-nd of the range. The pH is normally from about 7 to 9, but some variation is acceptable.

All percent by weights defined in this disclosure and claims are percents by weight based on the total weight of the composition.

As stated above, the concentration of the DHI in the composition as applied to the hair is from substantially 0.1 to 3%. It was also noted above that DHI is rather unstable and subject to -iir oxidation. It is therefore normally packaged for commercial use in the form of DAI in a slightly alkaline solution, under conditions that substantially exclude air. On storage, under alkaline conditions, the DAI hydrolyzes to form DHI. The raolecuiar weight of DHI is about 60% lower than the molecular weight of DAI. Accordingly, the concentration of DAI in the original package will be higher than the concentration of DHI in the package as ready for use. Of course, it is possible, if sufficient precautions are taken, to prepare an original package containing DHI.

If, :n acccraanco with a second embodiment of this invention, the DHI and oxidant are utilized together with oxidizable primary intermediates and couplers (hereinafter sometimes called "reactants") , the amounts of reactants will be about the same as utilized in conventional oxidant compositions. The amounts which will be tinctorially effective will vary with the selected reactants, as is well known in the art. The skilled artisan will have no difficulty in selecting the reactants and the amounts to be employed. Generally each reactant will be present in an amount of from substantially 0.01 to 2%, preferably 0.01 to 0.5%.

If DHICA or a lower alkyl ester of DHICA is employed in a formulation of the invention, the amount employed will typically be from substantially 0.1 to 1%.

The oxidant will be separately formulated to mix with the other components just prior to use, as illustrated in the examples. Thus, a product of the invention may comprise a package containing two separate units of aqueous compositions, one containing the oxidant, the other containing DHI and, if employed, a primary intermediate and a coupler.

The term "package" is used in the widest possible sense. It includes retail packages such as might be sold to an individual consumer with both compositions in the same box or other container. It includes also separate compositions m large amounts, such as night ice sold to a ceauty saion, whether or not the separate compositions are sold in the same container and are intended to be used together.

The compositions of this invention are particularly adapted tor co-dispensing from a compartmentalized package, such as the containers described m U.S. Pat. Nos. 3,241,722 and 4,103,772, the disclosures of which are incorporated herein by reference. In such co-dispensing pacKages, which have been employed previously with hydrogen peroxide dye svstems, the reactants are normally sealed in one compartment of the container and the hydrogen peroxide in another, and the container is constructed with means for mixing the separate ingredients in the container so that the resulting composition exits the container after such mixing.

There are two procedures for mixing which are normally employed. One utilizes an aerosol package and valve adapted so that the compositions in the compartments mix as they pass through the valve. In the other, the partition between the compartments is frangible and the container is formed with a mechanism which permits the partition to be pierced, or otherwise broken, so that the compositions mix prior to dispensing. 2epentiing upon the aesigr. cf the container, the resulting ~ixed composition can be dispensed under aerosol pressure, bv simple pouring or by any ether convenient method.

When such co-dispensing containers are employed with hydrogen peroxide systems, there is always danger of premature mixing because of accidental leakage through the partition. As a result the dye forming reaction, which is intended to take place m the open air takes place in a closed container thereby generating volumes of oxygen vnich may result in explosive pressure. There is no sucn danger when the oxidative salts of this invention are employed since the dye forming reaction does not generate oxygen.

Any of the conventional oxidizable primary intermediates and coupling agents used with ordinary oxidant compositions for hair coloring can be employed in the compositions of this invention to achieve, together with the DHI, a wide variety of tints and hues.

Table l below lists some of the preferred primary intermediates and couplers for use in this invention.

TABLE 1 Pnnary p-pnenylenediamine Intermediates: p-aminophenol o-aminophenol N,N-bis(2-hydroxyethyl)p-phenylenediamine 2,5-diaminopyridine p-toluenediamine m-aminophenol 1-naphthol -ammo-o-cresol 2-methylresorcinol 4 ,6-di (hydroxyethoxy) -meta-phenylenediamine meta-phenylenediamine Couplers: resorcinol Well known conventional additives usually employed in oxidative hair coloring compositions such as thickeners, surface active agents, antioxidants and fragrances may be included in the compositions of the invention. Such compositions are preferably liquid solutions, but they may be in the form of emulsions, suspensions, lotions, or gels. rarrace active :jer.ts enpicyea ir, the ayeing compositions cf this invention can ce aapnotenc, anionic, r.onionic or cationic. 3v way ct examples of the various types of surface active agents, there ran oe mentioned: higher aikylbenzene sulfonates: alkylnaphthalen-sulfonates: sulfonated esters of alcohols and polybasic acids; taurates; fatty alcohol sulfates; sulfates of branched chain or secondary alcohols; aikyldimethyl-benzylammonium chlorides, salts of fatty acids or fatty acid mixtures; N-oxyalkylated fatty acid 3lkanolamides, and the like. Illustrative of specific surfactants there can be mentioned: sodium lauryl sulfate; polyoxyethylene lauryl ester; myristyl sulfate: glyceryl monostearate: trlethanolamine oleate, sodium salt of palmitic methyl taurine; cetyl pyridinium chloride; lauryl sulfonate: myristyl sulfonate; 1 auric diethanolamide; polyoxyethylene stearate; ethoxylated oleoyl diethanolamide; polyethylene glycol amides of hydrogenated tallow; stearyldimethyl benzyl ammonium chloride; dodecylbenzene sodium suLfonate; 2-amino-2-methyl propanol; triethanolamine salt of p-lodecylbenzene sulfonate; triethanolamine salt of p-dodecylbenzene sulfonate; nonylnaphthalene sodium sulfonate; dioctyl sodium sulfosuccinate; sodium N-methyl-N-oleoyl taurate; oleic acid ester 3t sodium isothionate; sodium dodecyl sulfate and the sodium salt of 3-diethyl tridecanol-6-sulfate and the like. The quantity of surface active agent can vary over a wide range, such as from substantially 0.05% to 15% and preferably from substantially 0.10 to 5% by weight of the composition. -- t r.icnenir.a ^uent r.ay also be incorporated in the ayeing jomposition or this invention vnich may be one or several of those rommonr/ used in hair dyeing. These are exemplified by such rroaucts as sodium alginate or gum arabic, or cellulose derivatives, iucn as nethylcellulose e.g.. Methocel 60 HG, or the sodium salt of .-arcoxyTrethylcellulose, or hydroxyethylcellulose, e.g., Cellosize ^p-;o nr acrylic polymers, such as polyacrylic acid sodium salt, or inorganic thickeners, such as bentonite. The quantity of this thickening agent can also vary over a wide range, even as high as 20%. Ordinarily it will range from substantially 0.5 to 5% by weight of the composition. The viscosity of the composition may vary from about I cps to about 100,000 cps. For a typical lotion formulation, composition viscosity is from about 100 cps to about 10,000 cps.

It may also be useful to incorporate an antioxidant in the present dye compositions. A variety of antioxidants are known in the prior art which would be useful for this purpose. Among these mention may be made of the inorganic sulfites, e.g., sodium sulfite, thioglycollic acid and other mercaptans, butylated hydroxytoluene, sodium dithionite, various forms of ascorbic acid and their derivatives, e.g., sodium ascorbate, erythorbic acid, ascorbyl pa Imitate, ascorbyl laurate, etc. The quantity of antioxidant used can vary appreciably. However, the concentration will, in general, be up to substantially 1%, typically 0.001 to 1% by weight.

/ 'X The dyeing compositions cf this invention are preferacly aqueous compositions. The term aqueous composition is used herein in its usual generic sense as embracing any water-containing composition useful for the present purposes. This includes true solutions of the dye components aqueous medium, either alone or in conjunction with other materials, which are also dissolved or dispersed in the aqueous medium. The term aqueous composition also encompasses any mixture of the chlorite and the dye forming reactants with the aqueous medium either alone or together with other ingredients. The various components may be colloidally dispersed in the medium or may merely be intimately mixed therein. Moreover, the aqueous medium may comprise water or water and an additonal or auxiliary solvent. Typical auxiliary solvents which nay be used to enhance the solubility of the components include ethanol, carbitol, isopropanol, propylene glycol, ethylene glycol, diethylene glycol, diethylene glycol monoethyl ether, glycerine, etc.

The aqueous dyeing compositions of this invention can be prepared by conventional methods used in the hair dyeing art. Thus, they can be prepared by dissolving or suspending the components in the selected media with adequate mixing. Preparation may take place at ambient temperatures, i.e., 20° to 35°C., but solubility and rate of preparation can be enhanced utilizing elevated temperatures, for example 40° to 100°C. -19 The ccapour.as enpicyea ir. this invention are ail known cr can ce prepared by Known procedures. 3y way of specific example but without limitation, there follows a description or various known routes for the preparation of derivatives of N-suDstituted-5,6-dihydroxyindoles which are useful in the present invention. fl) Synthesis by cyciization of a dopamine derivative: A suitable i ,-i-'Uhyaroxy-N-substituted phenethylamine material is converted by oxidative cyclization followed by chemical reduction to the N'-substituted-dihydroxy indole as per the method for preparation of II-raethyl-5,6-dihydroxy indoles from opinepnrine described by G.L. Mattok and R.A. Heacock in the Canadian .Journal of Chemistry, Volume 42, p. 284 (1964). ror example, .'J-isopropyl-3, 4-dihydroxyphenethylamme (II) ran be oxidized by an alkaline ferricyanide solution folllowed by reduction with ascorbic acid to give N-isopropyl-5,6-:ihvarcxyindole 'HI) : zc m. 24 7 4 9 Similarly N-< 4-ammccuty 1; -5-6-aihyarcxyindole (V) can be obtained from 3 , 4-dihyarcxy-N-( 4-nitrabutyl) -phenethv lamme (IV): b) Synthesis by condensation of a benzenoid compound and a r.itrcqen containing compound.

An alternative synthetic procedure is available by the methods described by A. Reissert in Chemische Berichte, Volume 30, page 1030 (1897) and C.D. Nenitzecu in Bulletin of the :hemistry Society of Fumania, Volume 11, page 37 (1929) whore the .ndole :s produced upon the condensation of a benzenoid radical -■ Ltr. in appropriate M-ccntaining material. For example, N'-(2-nydrcxyethyl) 5 , 6-dihydroxy indole (VI) can be obtained upon rxiiative coupling of catechol (VII) with N-vinyl ethanolamine 33T rollowed fcv reduction. ch 3ZI ;c) Synthesis cy addition of indole to an aryl compound is ay the direct addition cf the indole to an aryl or benzyl halide cr aziae to give the aryl cr arylalkyl N-substituted-5,6-iihydroxymaole. Specifically, 5,6-diacetoxyindole (IX) is reacted with 2,4-aimtro-f luorobenzene (X) to give, after r.ydrclysis of the acetate radicals, N-(2,4-dinitropheny)-5 ,-6-iihydroxymdole (XI) : The following examples are illustrative of this invention and -heir use. They illustrate the advantages of the compositions of -he invention.

The tristimulus values in the examples are standard Hunter :hro=acity values obtained by procedures well known to those skilled in the art. The values recorded manifest the ability of the compositions of the invention to be usefully employed in hair coloring processes. 22 In the Hunter rristimuius System, L is a measure of lightness nd darkness that is, the aepth of the color of the hair tress. The over the value of L the darker the color.

A decrease in the value of L indicates a darkening of the hair ress. In the case of bleached and blended gray hair, a lowering of he value of L shows deposition of hair dye on the tress.

The a value is a measure of the greenness or redness of the lair's color. As the a value increases, the hair has a more prominent red tonality. A lowering in the a value results in greener shades. The b value is a measure of the yellow and blue color. Higher b values indicate a more yellow hue in the hair.

Example l DHI WITH VARIOUS OXIDIZING AGENTS A DHI composition was prepared containing 1.85 parts by weight jt CHI, 0.2 parts by weight thioglycolic acid (TGA -an antioxidant) and "3 parts by weight of water adjusted to pH 6.5 with hydrochloric acid. This solution was employed as a standard solution to determine the efficacy of a number of oxidizing agents including those reported in United States Patent 3,236,734. c <+ 7 4.-2 "or each test, approximately 16 ml cf the DHI solution was combined with -4 g of an aqueous solution of the oxidant under test in the solutions aefinea in Table 2. The solution was applied to swatches of gray hair from the same source and left for 2 0 minutes. The treated hair was then rinsed, shampooed and dried. The dyeing conditions (concentrations, dyeing time, pH etc.) are chosen such that the experimental conditions of US 3,236,734 are reproduced as closely as possible The concentration of DHI is equivalent, on a molar basis to the concentration of the hydrochloride of 2,4-iihydroxy phenylamme (Example 19 of US 3,236,734) and the concentration of the oxidants, sodium iodate, potassium persulfate, sodium perborate, is as described in this example. Sodium bromate and sodium chlorate (listed in the patent without specification of conditions) were used at equimolar concentration as sodium iodate.

Under these conditions, only sodium chlorite (Entry 9) and perborate (Entry 3) dye the hair to colors judged to be useful based on darkness and tonality. Perborate affords peroxide in aqueous solution. It is equivalent to aqueous peroxide itself - or to other peroxide sources, such as percarbonate, urea peroxide et cetera.

TABLE 2 Dyeing of Gray Hair with Formula A (High DHI Concentration) ■:ntry Oxidant, Added to 16cc DHI Solution pH Color 0.4g NalO^, 0.4g HOAc, 3.2g H^O ; 0.8g k2S2O0, 0.4g HOAC. 2.8G H20 3 0.3g NaBO^, 0.4g Na^O,, 3.3g H20 4 0.4g NaBrOj, 0.4g HOAc, 3.2g H^O 0=4g NaClO^, 0.4g HOAc, 3.2g H20 6 4g aq. NaOCl (4-6%) 4g 6* H PO 2 2 4g 6% H2°2' 0,4<? urea 0.2g NaC102, 0.4g HOAc, 3.4g H20 4.6 35.6 0.4 6.7 Gray 2.4 34.2 0.8 7.2 Gray 9.2 22.8 0.9 2.3 Die. Gray 4.4 27.3 -0.2 4.4 Gray 4.5 34.4 0.6 6.5 Gray .7 30.7 0.2 4.8 Gray 6.0 27.9 0.5 4.4 Gray 6.0 27.0 0.5 4.2 Gray 4.4 18.7 0.6 1.6 Die. Gray/BlJc 1 undyed hair: L 35.8 a 0.2, b 6.6 Similar results are obtained with N-methyl- and N-ethyl-5 ,6,dihydroxyindole and with the corresponding 2-methyl- and 2-ethy1-compounds.

. \ 'V, EXAMPLE 2 COMPARISON OF SODIUM CHLORITE (ENTRY il) WITH OTHER OXIDANTS This example was conducted to show the unexpected superiority of sodium chlorite as an oxidant compared with hydrogen peroxide or other sources of peroxide, such as perborate.

Formulations were prepared, which contained DHI at a lower concentration than in Example l (DHI concentration 0.5% after mixing with oxidant) . This would be a preferred concentration for a commercial product, since DHI is an expensive raw material. The formulations contain different alkaline agents to adjust the pH to the desired value. This is summarized in Table 3.

Entries 1-5 demonstrate, that, in contrast to sodium chlorite, peroxide, or its substantial equivalent perborate are only efficient as oxidants at alkaline pH.

Entries 8, 9 and 10 show, that the efficacy of peroxide is further increased, when ammonia is used as the alkalizing agent. 24 7 48 Entry II illustrates the use cf sodium chlorite.

The data demonstrate, that with peroxide as oxidant, the efficacy cf sodium chlorite can be approacnea (but still not matched) only at high pH ana high ammonia concentrations both of which are unacceptable because of the strong odor of ammonia and the likelihood of hair damage at the high pH. Only sodium chlorite imparts a deep brown color at low pH, without ammonia, from solutions containing relatively low concentrations of DHI.

TABLE 3 Dyema of Gray Hair With Low Concentration of DHI 0.5% Entrv Oxidant (%) H2°2 H2°2 •j o 2 2 NaBO 3 NaBO.

NaBO, NaBO 3 NaBO 3 (0.5) (0.5) (0.5) (1.5) (1.5) (1.5) (3.0) (1.5) Base< %) MBA (1.8) HEA MEA HEA MEA Et NH(1.6) Et NH(1.6) NH3 (0.5) pH Hunter L 9.9 27.6 8.0 32.7 7.0 32.4 9.9 28.3 8.0 32.8 .5 27.8 .5 27.3 9.8 25.4 Crist, val. a b 0.2 2.9 0.2 0.4 0.2 0.4 0.3 0.4 0.6 6.2 5.9 3.0 6.1 3.3 3.4 2.8 color dark gray gray gray dark gray gray gray gray dark gray NaBO. 2.2, '.H. 5.3 Z5.0 :.5 2.C iarK :: NaBO. (1.5) NH. 1.31 10.8 21.7 3.8 ; . 0 dark gray :: NaClO. 3.6) -7.0 ::.9 1.5 3.9 dark brown Similar results are ootained with N-isopropyl-5,6-dihydroxyindole and with N-(2,4-dinitropneny1)-5,6-dihydroxyindole.

EXAMPLE 3 ADDITIONAL COMPARISONS OF SODIUM CHLORITE This example was conducted to compare the efficacy of sodium chlorite with oxidizing agents specifically mentioned in United States Patent 3,194,734.

The following compositions were prepared: (as described in US ; ,194,734) FORMULA 3 FORMULA C FORMULA D Nonyi-Nonoxynol-49 3 MSA 2 TGA 150%) 0.1 Water 87.9 3AI i Nonyl-Nonoxynol-49 9 Ammonia (20%) 3 TGA (50%) 0.1 i'ater 86.9 DAI 1 Nonyl-Nonoxynol-49 9 Urea 7.5 Diethylamide 2 TGA (50%) 0.1 Water 80.4 All components were dissolved in water with heating to about 50-60°C, until complete dissolution of the various ingredients. This temperature increase brings about the deacetylation of DAI and therefore the formation of 5,6-dihydroxyindole (DHI). l g DAI results in approximately 0.64 g DHI.

The ingredients and methods of preparation of the formulations ire identical to what has been described in US 3,194,7 34 (examples 1,2 and 3) with one exception: Nonyl-Nonoxynol 49 was used instead of "Cemulsol 132", due to the unavailability of this component, cemulsol 132 is a non-ionogen condensation product of ethylene oxide and a naphthol compound. Nonyl-Nonoxynol 49 is a non-ionogen condensation product of ethylene oxide and a benzene compound. This substitution has no effect on the described dyeing results. 2 4 7 4 9 2 In each entry the oxidant was added immediately before use to he formulation (ambient temperature), applied to hair and left for 3 nnutes. The hair was rinsed with water, shampooed and dried, lunter Tristimulus values were measured.

The results are shown in Table 4.

TABLE 4 Dyeing of Gray Hair with Formulas B, C and D (Low DHI Concentration) Entrv Dye Solution es! Color lOcc formula c, icc 6% H10.0 lOcc formula D, 0.2g(NH4)2S20fl 9.2 lOcc formula C, 0.02g CoCl^ 9.9 lOcc formula C, 0.02g Mn-lact. 9.2 lOcc formula B, lcc 6% H202 9.9 lOcc formula B, 0.4g NaClOjin lg HjO 7.0 22.5 1.2 31.9 0.6 27.6 0.0 29.4 -0.3 26.8 0.2 21.9 1.5 1.0 4.7 2.7 3.4 2.8 3.9 Ok. Gray Gray Gray Bluish Gray Gray Brown After addition of oxidant. with H202 (Table 4, Entry 1), the darkness of the hair is comparable to sodium chlorite (Table 3, Entry 6). However, the tonality is different.

To oDtam a aarx dyeing as m Table 4, Entry 1 (with rei. low DHI concentration and H„02 as oxidant) the presence of a substantial amount of ammonia is required. Without ammonia at equal DHI-concentration, the dyeing is weaker (see Table 4, Entry 5).

Tonality; An example of Hunter Tristimuius values of natural dark and medium brown hair is the following: L a b dark brown 16.0 1.8 2.6 med. brown 23.6 3.0 6.9 It is apparent that at a darkness level of L at about 22, the fa-value should be more than twice the amount of the a-value. This is achieved with hair dyed with DHI/sodium chlorite (Table 4, Entry 6), but not with hair dyed with DHI/H202 at the conditions of Entry l, Table 4. Only the DHI/sodium chlorite dyed hair appears natural brown.

EXAMPLE 4 COMPOSITIONS CONTAINING PRIMARY INTERMEDIATE AND COUPLER An aqueous solution, containing 0.3% DHI, 0.4% p-aminophenol, 0.4% 5-amino-o-cresol in a pH 7 phosphate buffer was prepared (solution l). 3 ml of an aqueous solution of sodium chlorite (4 %) was added

Claims (14)

to r zi cr solution 1; tr.e mixture was applied to (gray) hair and Left tor 15 minutes. The hair was rinsed with water, shampooed and :riea. The nair had a medium brown color with Hunter Tristimulus values L21.Sal.9b5.i. If sodium chlorite was omitted in an otherwise identical dyeing solution, the hair was dyed to a light crown color having the Hunter Tristimulus values L 28.5 a 1.3 b 6.9. If DHI was omitted in an otherwise identical dyeing solution (with sodium chlorite), the hair was dyed to a light brown color with Hunter Tristimulus values L 27.9 a 2.1 b 7.4. Similar results are obtained with N-methyl- and N-ethyl-5,6,dihydroxyindole and with the corresponding 2-methyl- and 2-ethyl- compounds. -32- 2 4 / h 9 2 WHAT WL CLAIM IS:

1. A dye composition comprising an aqueous solution containing from substantially 0.1% to 5% by weight of sodium chlorite together with from substantially 0.1% to 3% by weight of a compound selected from the group consisting of an indole which is a melanin nrcrursor represented by the formula: wherein R is hydrogen, alkyl, hydroxyalkyl, aminoalkyl, each alkyl containing up to eight carbon atoms, aryl, or substituted aryl containing up to three reaction inert substituents, is hydrogen or alkyl containing up to six carbon atoms; 5,6-dihydroxyindoline? and mixtures of said compounds.

?, A dye composition of claim 1 wherein the melanin precursor is 5,6-dihydroxyindole. R

3. A hair dye composition of claim 1 or ^ further comprising at least one of the following: surface active agent in an amount up to substantially 15% by weight, thickening agent in an amount up to substantially 20% by weight and antioxidant in an amount up to substantially 1% by weight.

4. An oxidative dye composition of claim 1, 2 or 3 additionally containing sufficient amounts of an oxidative primary intermediate and coupler to react and form a tinctorially effective amount of a hair dye.

5. An oxidative dye composition of claim 4 wherein the amounts of oxidative primary intermediate and coupler are each from substantially 0.01 to substantially 2% by weight.

6. An oxidative dye composition of any one of claims 1 to 5 additionally containing from substantially 0.1 to 1% by weight of 5,6-dihydroxyindole-2-carboxylic acid or a lower alkyl ester thereof.

7. A package containing two separate compositions, the first comprising an aqueous solution containing sodium chlorite, the second comprising an aqueous solution containing a compound selected • V r -34 £14 i H 3 2 tron the group consisting cf an indole which is a melanin precursor represented by the formula: wherein R is hydrogen, alkyl, hydroxyalkyl, aminoalkyl, each alkyl containing up to eight carbon atoms, aryl, or substituted aryl containing up to three reaction inert substituents, is hydrogen or alkyl containing up to six carbon atoms; 5,6-dihydroxyindoline and mixtures of said compounds; the amount of sodium chlorite in the first composition being sufficient so that when the two compositions dre mixed, the amount of sodium chlorite salt in the resulting composition will be from substantially 0.1% to 5% by weight; the amount of melanin precursor in the second composition being sufficient so that when the two compositions are mixed, the resulting composition will contain from substantially 0.1% to 3% by weight of melanin precursor .

8. A package of claim 7 wherein the melanin precursor is 5,6-dihydroxyindole. R 35 / "

9. A package zf cia;:- 7 or 8, either of the first or second compositions further comprising at least one of the following in an amount such that resulting composition will contain: surface active agent in an amount up to substantially 15% by weight, thickening agent in an amount up to substantially 20% by weight and antioxidant in an amount up to substantially 1% by weight.

10. A package of claims 7, 8 or 9, the second composition additionally containing sufficient amounts of an oxidative primary intermediate and coupler to react and form a tinctorially effective amount of a hair dye.

11. A package of claim 10 wherein the amounts of oxidative primary intermediate and coupler are each from substantially 0.01% to substantially 2% by weight.

12. A package of any one of claims 7 to 11, additionally containing from substantially 0.1 to 1% by weight of 5,6-dihydroxy-indole-2-carboxylic acid or a lower alkyl ester thereof.

13. A method of dyeing hair comprising applying to the hair an oxidative composition of any one of claims 1 to 6.

14. A dye composition of claim 1 substantially as reinbefore defined with particular reference to any one ofJ the foregoing Examples.