the 1 - naphthol compounds ( i ) of the present invention , or salts thereof , are quite suitable for use generally as dye couplers in oxidative dye compositions . the oxidative dye composition further contains an oxidation dye precursor such as a primary intermediate , e . g . p - phenylenediamine , or a hydroxyindole , e . g . 5 , 6 - dihydroxyindole , the composition being oxidizable with hydrogen peroxide or other oxidant to produce an array of colors . it is particularly surprising that when a compound of formula i is coupled with a p - aminophenol derivative , the color imparted to hair is much redder than when 1 - naphthol is coupled with the same p - aminophenol derivative . the bright red colors obtained when couplers of formula i are coupled with a p - amino - phenol derivative are not achievable by the current state of the art . in a particular useful and preferred aspect of the present invention , it has been found that certain of the 2 - substituted - 1 - naphthol couplers ( i ) and their salts , when employed in an alkaline oxidizing medium with a suitable oxidation dye precursor such as a primary intermediate , especially p - aminophenol primary intermediates , unexpectedly impart to the keratin fibers a brighter red shade . moreover , it has also been found that surprisingly long - lasting shades are obtainable , which resist fading caused by weathering and / or light . in this regard , they are more long - lasting than the red shades obtained when 1 - naphthol is employed as the coupler . the bright red shades produced by the couplers ( i ) when employed with p - aminophenols are particularly important to achieve a true auburn hair color having a realistic tonal impression . it should be understood that the red colors referred to herein are the actual hues obtained when the hair is dyed with the coupler ( i ) as the only coupler and a suitable primary intermediate , i . e ., a primary intermediate used in connection with this preferred aspect of the invention ( such as p - amino - phenol ), that provides with coupler ( i ) bright red color to the hair fiber . the suitable primary intermediate may be easily determined by actual testing with the couplers ( i ) of the present invention , in accordance with the procedures outlined in the examples . the dye compositions of the present invention comprise from about 0 . 001 to about 10 %, preferably from 0 . 01 to about 5 %, most preferably from about 0 . 05 to about 2 . 5 %, of a coupler , all or part of which coupler may be the coupler ( i ), from about 0 . 001 to about 10 %, preferably from about 0 . 05 to about 5 %, most preferably from about 0 . 2 to about 2 . 5 %, of an oxidation dye precursor , such as a primary intermediate or an hydroxyindole , and water . the proportions and amounts of the several constituents in the hair dye composition will depend on the nature and amount of the dye components , the tonal impression to be created , and the color of the hair to be dyed . whether to use the coupler ( i ) alone or in combination with other couplers or whether to include two or more primary intermediates , will depend on the shade of the color desired . generally , the coupler to primary intermediate molar ratio is from about 0 . 1 : 1 to about 10 : 1 , preferably from about 1 : 1 to about 4 : 1 . the dye compositions of the present invention comprise the coupler ( i ) and , optionally , one or more additional coupler compounds , for example , m - phenylenediamines , such as 2 , 4 - bis ( 2 - hydroxyethoxy )- 1 , 5 - diaminobenzene and 2 , 4 - diaminophenoxy - ethanol ; m - amino - phenols , such as m - aminophenol , 5 - amino - 2 - methylphenol , 5 -( n - 2 - hydroxyethylamino )- 2 - methylphenol , 2 - methyl - 5 - carbamyl - methylaminophenol and 5 - amino - 2 , 6 - dimethylphenol ; m - acetamidophenols , such as 5 - acetamido - 2 - methylphenol ; m - ureido - phenols ; 1 - naphthol ; resorcinols ; and heterocyclic couplers , such as 6 - hydroxy - benzomorpholine , 2 - 6 - diaminopyridine and 1 - phenyl - 3 - methylpyrazolone . the dye compositions of the instant invention contain at least one primary intermediate . combinations of primary intermediates may be employed . primary intermediates which can be utilized in the invention are well known to those skilled in the art . the primary intermediates incorporated in the dye composition of the present invention are preferably : ( i ) p - phenylenediamines , for example , dye compounds of the formula ii ## str2 ## wherein r 3 and r 4 are substituent groups including hydrogen , alkyl , hydroxyalkyl , aminoalkyl , and acylaminoalkyl ; r 5 is hydrogen , alkyl , alkoxy or halogen ; r 6 is hydrogen , halogen , alkyl or alkoxy , and n is 1 or when r 6 is methyl n is one or two ; each of the aforementioned alkyl moieties having from 1 to 6 , preferably from 1 to 4 carbon atoms ; compound ( ii ) being in the form of the free base or in the form of an acid salt , such as the hydrochloride ; a ( ii ) p - aminophenols , for example , dye compounds of the formula iii ## str3 ## wherein r 7 is hydrogen , c 1 - c 6 alkyl , hydroxy c 1 - c 6 alkyl , c 1 - c 6 alkoxy , c 1 carboxyl , or halogen , and n is one or when r 7 is methyl n is one or two . illustrative compounds ii include p - phenylenediamine ; 2 , 6 - dimethyl - 3 - methoxy - p - phenylenediamine dihydrochloride ; 3 - methoxy - 4 - amino - n , n - dimethylaniline sulfate ; and n , n -- bis ( 2 - hydroxyethyl )- p - phenylenediamine sulfate . illustrative of the compounds of formula iii are p - aminophenol ; 4 - amino - 2 , 6 - dimethylphenol ; 5 - aminosalicylic acid ; 4 -[( 2 - acetamidoethyl )- amino ] phenol sulfate ; 4 - amino - 2 - methylphenol ; 4 - amino - 3 - methylphenol hydrochloride , and 2 , 5 - dimethyl - 4 - aminophenol . particularly preferred primary intermediates include p - phenylenediamine , n , n - bis ( 2 - hydroxyethyl )- p - phenylenediamine , p - aminophenol , p - amino - m - methylphenol , p - amino - o - methylphenol , 5 - aminosalicylic acid , 2 , 5 - diaminotoluene , and 4 - amino - 1 - naphthol . most preferred primary intermediates include p - phenylenediamine , p - toluenediamine , p - aminophenol , 4 - amino - 2 - methylphenol , and n , n - bis ( 2 - hydroxyethyl )- p - phenylenediamine sulfate . mixtures of primary intermediates of formula ii and formula iii may be employed . for example , two or more primary intermediate compounds ( ii ) and ( iii ) may be incorporated into the dye compositions of the present invention . the hair dye composition disclosed herein may also include , in addition to the primary intermediate compounds ( ii ) and ( iii ), one or more dyes such as anthraquinones , nitrobenzenes , diphenylamines , azo dyes , indoanilines , indophenols and indamines . the dye compositions of the present invention include an aqueous , alcoholic or hydroalcoholic medium , as a vehicle or carrier . the alcohol moiety , if present , is usually a lower alkanol of from 1 to 6 carbons , especially ethanol or propanol , but may be a glycol having a total of up to 10 carbons , especially less than 6 carbons , such as propylene glycol , butyl glycol and diethyleneglycol monobutyl ether . the vehicle is generally from about 1 to 75 % by weight of the composition . typically , the alcohol moiety , if present , comprises about 10 to about 50 % by weight of said vehicle , and the vehicle is typically from about 10 to about 50 % by weight of the composition . the compositions of the present invention may further include a cationic , anionic , nonionic or amphoteric surface - active agent in an amount of up to about 20 % by weight , preferably from about 0 . 5 to about 10 % by weight . representative surface - active agents include octoxynol - 1 , nonoxynol - 4 , oleic acid and salts thereof , lauric acid and salts thereof , merquat 100 , polyquaternium 6 , cocoamidopropylbetaine and sodium oleoamphopropionate . the hair dye compositions of the present invention may also include one or more adjuvants such as perfumes ; antioxidants , such as sodium sulfite and sodium thioglycolate ; sequestering agents , such as edta ; alkalizing agents , such as ammonia or an alkanolamine ; and acidifying agents , such as oleic acid , acetic acid and phosphoric acid . these adjuvants are present in an amount effective to provide their functional activity . the ph of the compositions of the present invention ranges typically from about 8 to about 11 . although it is preferred to admix the developer , e . g ., hydrogen peroxide , and the dyeing composition at the moment of use , compositions containing hydrogen peroxide are within the scope of this invention . the hydrogen peroxide developer is typically an aqueous solution of h 2 o 2 having a concentration between 5 and 50 volumes , preferably between 10 and 40 volumes . upon mixing with the developer , the primary intermediate is oxidized and thereafter reacts with the coupler to provide the intended color . after mixing , the mixture is applied to hair for typically from about 5 to about 60 minutes , especially between about 20 and about 45 minutes . as known in the art , the dye composition often contains more than one primary intermediate and more than one coupler , to provide the shade of hair color desired . the invention is further described by way of the examples below . it should be noted that , unless otherwise indicated , all percentages herein are percentage by weight , based on the total weight of the composition . 5 . 0 g of test composition are mixed with 2 . 5 g of hydrogen peroxide solution ( 20 vol .). the resultant mixture is applied to piedmont hair and permitted to remain in contact with the hair for 30 minutes . the thus dyed hair is then shampooed and rinsed with water . tristimulus values are then determined using a hunter tristimulus colorimeter ( model d25m - 9 ). the tristimulus a value is an indicator of the degree of greenness and redness . a larger a value indicates a redder color . a smaller a value indicates a greener color . the following comparative compositions a and b were prepared in accordance with the general procedure . ______________________________________ a b______________________________________1 - naphthol 0 . 58 % -- 2 - methyl - 1 - naphthol -- 0 . 64 % p - phenylenediamine 0 . 43 % 0 . 43 % ethyl alcohol 30 . 00 % 30 . 00 % ammonium hydroxide qs ph 9 qs ph 9water qs 100 % qs 100 % ______________________________________ composition a imparted a dark blue violet color to the hair . composition b imparted a vivid violet color to the hair . tristimulus values , reported in table 1 below , show that composition b ( in accordance with the present invention ) produced a swatch having a larger a value than that of the swatch dyed with composition a . thus , use of 2 - methyl - 1 - naphthol as a coupler produced a redder color than when 1 - naphthol was used as the coupler . table 1______________________________________tristimulus values dyed swatches primarycomposition intermediate coupler l a b______________________________________a p - phenylenediamine 1 - naphthol 14 . 5 3 . 6 - 3 . 7b p - phenylenediamine 2 - methyl - 1 - 14 . 0 5 . 4 - 3 . 6 naphthol______________________________________ the following comparative compositions c and d were prepared in accordance with the general procedure . ______________________________________ c d______________________________________1 - naphthol 0 . 48 % -- 2 - methyl - 1 - naphthol -- 0 . 53 % n , n - bis ( 2 - hydroxyethyl )- 0 . 97 % 0 . 97 % p - phenylenediamine sulfiteethyl alcohol 30 . 00 % 30 . 00 % sodium sulfite 0 . 40 % 0 . 40 % ammonium hydroxide qs ph 9 qs ph 9water qs 100 % qs 100 % ______________________________________ composition c imparted a greenish blue color to the hair . composition d colored the hair blue . as is evident from the results of table 2 , the swatch treated with composition d ( a composition in accordance with the present invention ) has a larger a value than the swatch treated with composition c . thus the use of 2 - methyl - 1 - naphthol as a coupler produced a redder color on hair than when 1 - naphthol was used as the coupler . table 2______________________________________tristimulus values of dyed swatchescompo - primarysition intermediate coupler l a b______________________________________c n , n - bis 1 - naphthol 20 . 3 3 . 4 - 20 . 4 ( 2 - hydroxyethyl )- p - phenylenediamined n , n - bis 2 - methyl - 20 . 4 7 . 0 - 21 . 8 ( 2 - hydroxyethyl )- 1 - naphthol p - phenylenediamine______________________________________ the following comparative compositions e and f were prepared in accordance with the general procedure . ______________________________________ e f______________________________________1 - naphthol 0 . 40 % -- 2 - methyl - 1 - naphthol -- 0 . 44 % p - aminophenol 0 . 30 % 0 . 30 % propylene glycol 30 . 00 % 30 . 00 % sodium sulfite 0 . 20 % 0 . 20 % ammonium hydroxide qs ph 9 qs ph 9water qs 100 % qs 100 % ______________________________________ composition e imparted a red - violet color to the hair . composition f imparted a red color to the hair , without the violet hue obtained with composition e . table 3______________________________________tristimulus values of dyed swatches primarycomposition intermediate coupler l a b______________________________________a p - aminophenol 1 - naphthol 32 . 8 21 . 4 8 . 8b p - aminophenol 2 - methyl - 38 . 7 26 . 3 13 . 6 1 - naphthol______________________________________ ______________________________________ compositions g h i______________________________________2 - propyl - 1 - naphthol 0 . 53 % -- -- 2 - dimethylaminomethyl - 1 - -- 0 . 57 % -- naphthol2 -( β - propenyl )- 1 - naphthol -- -- 0 . 53 % 2 - methyl - 1 - naphthol -- -- -- p - amino - m - methylphenol -- -- 0 . 35 % p - amino - o - methylphenol sulfate -- -- -- p - aminophenol 0 . 30 % 0 . 30 % -- ethyl alcohol 50 . 00 % 50 . 00 % 50 . 00 % ammonium hydroxide qs ph 9 qs ph 9 qs ph 9water qs 100 % qs 100 % qs 100 % ______________________________________ compositions j k______________________________________2 - propyl - 1 - naphthol -- -- 2 - dimethylaminomethyl - 1 - -- -- naphthol2 -( β - propenyl )- 1 - naphthol -- -- 2 - methyl - 1 - naphthol 0 . 44 % 0 . 44 % p - amino - m - methylphenol -- -- p - amino - o - methylphenol sulfate -- 0 . 97 % p - aminophenol 0 . 35 % -- ethyl alcohol 30 . 00 % 30 . 00 % ammonium hydroxide qs ph 9 qs ph 9water qs 100 % qs 100 % ______________________________________ the above compositions g , h , i , j and k were prepared in accordance with the general procedure composition g dyed the hair an orange - red . composition h dyed the hair a reddish - brown . composition i dyed the hair a red - violet color . composition j dyed the hair a deep red . composition k dyed the hair a cherry red . european patent application 345 , 728 indicates that 5 - amino - salicylic acid and 1 - naphthol produced a vivid reddish color on hair . composition l ( a composition in accordance with european patent application 345 , 728 ) and composition m ( a composition in accordance with the present invention ) were prepared by the general procedure . ______________________________________ l m______________________________________1 - naphthol 0 . 40 % -- 2 - methyl - 1 - naphthol -- 0 . 44 % 5 - aminosalicylic acid 0 . 45 % 0 . 45 % ethyl alcohol 50 . 00 % 50 . 00 % ammonium hydroxide qs ph 9 qs ph 9water qs 100 % qs 100 % ______________________________________ tristimulus values of the dyed swatches are reported in table 4 , below . it was evident from the results reported in table 4 and confirmed by visual observation that the use of 2 - substituted - 1 - naphthol as a coupler afforded a red color whereas , contrary to the teaching of european patent application 345 , 728 , when 1 - naphthol was employed as the coupler , the resultant color was violet not red . table 4______________________________________tristimulus values of dyed swatches primarycomposition intermediate coupler l a b______________________________________l 5 - aminosalicylic 1 - naphthol 64 . 8 7 . 3 15 . 7 acidm 5 - aminosalicylic 2 - methyl - 1 - 63 . 2 10 . 8 16 . 7 acid naphthol______________________________________ to demonstrate that dyestuffs prepared through use of a 2 - substituted - 1 - naphthol coupler of the present invention are more acid - resistant ( in other words , more acid - fast ) than dyestuffs prepared through use of the 1 - naphthol coupler , the following test was conducted . a tress of bleached hair was dyed with a combination of p - aminophenol and 2 - methyl - 1 - naphthol . as a control , a like tress was dyed with a combination of p - aminophenol and 1 - naphthol . both dyed tresses were treated as follows : the dyed tress was immersed for 3 hours , at a temperature of 50 ° c ., in a solution having the following composition : ______________________________________sodium chloride 1 % ( w / w ) lactic acid 0 . 1 % ( w / w ) dibasic sodium phosphate 0 . 1 % ( w / w ) histidine monohydrochloride 00 . 25 % ( w / w ) deionized water qs 100 % ______________________________________ after such treatment with tristimulus values of the treated tresses were determined . the results are reported below . table 5______________________________________tristimulus values of treated tresses l a b______________________________________tress dyed using2 - methyl - 1 - naphtholas the couplerinitial value 28 . 4 24 . 2 11 . 8final value 32 . 0 23 . 7 13 . 0tress dyed using1 - naphthol as thecouplerinitial value 26 . 7 19 . 0 7 . 7final value 29 . 8 14 . 4 6 . 3______________________________________ in considering the above results it should be noted that the less the a value the greater the acid - fastness of the dye . the results reported above show that the change in a value ( a ) for the tress dyed with 2 - methyl - 1 - naphthol employed as the coupler was 0 . 5 ( 24 . 2 - 23 . 7 ). while the change in a value ( a ) for the tress dyed with 1 - naphthol employed as the coupler was 4 . 6 ( 19 . 0 - 14 . 4 ). thus , it is readily apparent that the use of 2 - substituted - 1 - naphthol as the coupler , in accordance with present invention , resulted in a dyestuff more than 9 times more acid - fast that the dyestuff prepared through use of the 1 - naphthol coupler of the prior art .
2 - substituted - 1 - naphthols when coupled with an oxidation dye precursor in an oxidative dye system produce a long lasting intense color to hair . use of such couplers makes available to the colorist novel oxidation hair dyes which surprisingly show a color shift to the red . dyestuffs prepared through use of the 2 - substituted - 1 - naphthol couplers are substantially more acid - fast compared to like dyestuffs using a 1 - naphthol coupler . compositions and a method of dyeing hair are also disclosed .