Abstract:
The invention provides new yellow-dye-forming couplers, new yellow dyes formed therefrom, and new photographic elements containing the new couplers. The new couplers have the structure (I): ##STR1## wherein ##STR2## has the structure (II) ##STR3## wherein each --R-- is independently a substituted or unsubstituted alkylene, alkoxylene, arylene, or aryloxylene group, and Q-- has the structure (III): ##STR4## wherein: each R 1  -- is independently t-butyl or a substituted aryl group; 
     each Z-- is independently H--, halo, or a substituted or unsubstituted alkyl, aryl, alkoxy, or aryloxy group; 
     each M-- is independently H-- or a substituent; and each R 2  -- is independently H-- or a substituent.

Description:
FIELD OF THE INVENTION 
     This invention relates to new dye-forming couplers and new yellow dyes formed therefrom and to photographic silver halide elements containing such new couplers. More particularly, the invention concerns new yellow-dye-forming tris couplers comprising three ketomethylene-containing coupling moieties bonded to a phosphorous-containing linking group. 
     BACKGROUND 
     Color images are commonly obtained in the silver halide photographic art by reaction between the development product of a silver halide developing agent (e.g., oxidized aromatic primary amine developing agent) and a color forming compound commonly referred to as a coupler. The reaction between the coupler and oxidized developing agent results in coupling of the oxidized developing agent to the coupler at a reactive site on the coupler, known as the coupling position, and yields a dye. The subtractive process of color formation is ordinarily employed in color photographic elements, and the dyes produced by coupling are usually cyan, magenta, or yellow dyes which are formed in or adjacent to silver halide emulsion layers sensitive to red, green, or blue radiation, respectively. 
     Many couplers well known for forming yellow dyes contain an open-chain ketomethylene group in the coupling moieties. One class of such couplers comprises acylacetanilides, such as pivalylacetanilides and benzoylacetanilides, described, for example, in U.S. Pat. Nos. 2,407,210; 3,265,506; 3,408,194; 3,894,875; and 4,157,919. 
     However, such known couplers often have drawbacks. 
     One such drawback is that silver halide photographic elements containing such couplers often exhibit lower than desirable photographic speed. That is, the elements require exposure to larger than desirable amounts of actinic radiation to finally yield a given level of dye image density. 
     Another common drawback of many acylacetanilide couplers is the relatively low level of maximum density (Dmax) and/or contrast yielded by the yellow dyes formed from such couplers in silver halide photographic elements. 
     A further common drawback is the relatively high equivalent weight of many yellow-dye-forming couplers. The term, &#34;equivalent weight&#34;, as used herein is equal to the molecular weight of the coupler divided by the number of efficiently reactive coupling moieties in the coupler molecule. Each efficiently reactive coupling moiety is capable of reacting with oxidized developing agent to form a colored dye moiety. The higher the equivalent weight of the coupler is, the larger is the mass of coupler that must be included in a photographic element layer in order to be able to produce the desired amount of developed image dye optical density. The need for a larger mass of coupler in a layer results in a thicker layer, which inherently reduces the transparency and optical sharpness of the layer. Thus, lower equivalent weight couplers allow for thinner, more transparent, optically sharper layers. Unfortunately, the overall mass of a coupler molecule must be relatively large in order to provide sufficient organic ballast to properly suspend the coupler molecules in droplets of high boiling organic liquid, referred to as coupler solvent, which are dispersed in the desired layer of the photographic element, and thereby anchor the coupler in the layer and prevent it from diffusing to adjacent layers or out of the element during processing with various aqueous processing liquids. Thus, the needs for lower equivalent weight and sufficient organic ballast are at apparent cross-purposes. 
     Also, some characteristics of acylacetanilide yellow-dye-forming couplers, in addition to their coupling speeds and efficiencies and their molecular and equivalent weights, can be significantly affected by the nature of any particular substituents that may be bonded to the coupling moieties at positions other than the coupling position, because such substituents remain bonded to the dye moieties formed by the coupling reaction. For example, it is known that the nature of such substituents can significantly affect the hue of the dye moieties and their mobility in a photographic element. Relatively immobile yellow dyes tend to provide images of higher granularity and higher sharpness, while more mobile yellow dyes can migrate slightly (often referred to as &#34;smearing&#34;) to provide reduced granularity and lower sharpness. The desired combination of hue and balance of granularity and sharpness may be different for various photographic elements, depending upon their intended uses. 
     There is therefore a continuing need for a new class of yellow-dye-forming couplers that can minimize the drawbacks described above, i.e., that can be incorporated in silver halide photographic elements without causing lower than desirable photographic speed, that can form yellow dyes in silver halide photographic elements that yield relatively high levels of maximum density (Dmax) and contrast, and that have relatively low equivalent weight, while at the same time having relatively high molecular weight to provide sufficient organic ballast for proper incorporation and anchoring in photographic element layers. It would also be desirable for such a new class of couplers to provide the flexibility to choose among various different substituents to have at positions on the coupling moieties other than the coupling position, in order to be able to tailor the effects of such substituents (effects such as described above) to meet particular needs in various photographic elements. Of course, the couplers should also exhibit all the other characteristics desirable for good photographic performance. 
     SUMMARY OF THE INVENTION 
     The present invention meets the above-noted need by providing new yellow-dye-forming couplers, new yellow dyes formed therefrom, and new photographic elements containing the new couplers. 
     The new yellow-dye-forming couplers provided by the invention are tris coupler compounds having the structure (I): ##STR5## wherein ##STR6## has the structure (II) ##STR7## wherein each --R-- is independently a substituted or unsubstituted alkylene, alkoxylene, arylene, or aryloxylene group, and Q-- has the structure (III): ##STR8## wherein: each R 1  -- is independently t-butyl or a substituted aryl group; 
     each Z-- is independently H--, halo, or a substituted or unsubstituted alkyl, aryl, alkoxy, or aryloxy group; 
     each M-- is independently H-- or a substituent; and each R 2  -- is independently H-- or a substituent. 
     The new yellow dyes of the invention are the dyes that are formed by coupling reaction of an oxidized photographic color developing agent and the new tris couplers of the invention. 
     The photographic elements of the invention each comprise a support having thereon a photographic silver halide emulsion layer and one or more of the new tris couplers of the invention. 
     The couplers, dyes, and photographic elements of this invention provide a number of advantages. 
     Photographic elements of the invention exhibit relatively high photographic speed that is not adversely affected by the couplers of the invention. 
     The yellow dyes of the invention formed from the couplers of the invention as image dyes in photographic elements of the invention yield relatively high levels of maximum density and contrast. 
     Couplers of the invention have relatively low equivalent weight, because each coupler molecule of structure (I) contains three efficiently reactive coupling moieties of structure (III) bonded to a central linking group of structure (II). Thus the equivalent weight of the couplers of the invention is only one third of their molecular weight, and layers in photographic elements of the invention containing such couplers can be made thinner and thus more transparent and optically sharper. 
     Conversely, the three coupling moieties plus linking group in couplers of the invention result in the couplers&#39; having relatively high molecular weights, which easily provide sufficient organic ballast to properly suspend the coupler molecules in coupler solvent and anchor them in layers of photographic elements of the invention. 
     Also, because the linking group of structure (II) in couplers of the invention is bonded to the coupling moieties of structure (III) through a substituent on the coupling position, the new class of yellow-dye-forming couplers of the invention provides the flexibility to choose among various different substituents (represented by R 1  --, Z--, and M-- in structure (III)) to have at positions other than the coupling position of the coupling moieties. Thus, one is able to tailor the effects of such substituents described above (e.g., effects on coupling speed and efficiency, effects on coupler molecular and equivalent weight, effects on dye hue, effects on image dye granularity and sharpness, etc.) to meet particular needs in various photographic elements of the invention. 
     Furthermore, it was unpredictable that inclusion of the phosphorous-containing linking group of structure (II) in the coupler molecules would still yield couplers having the other characteristics necessary or desirable for good photographic performance. The couplers of the invention have been unexpectedly found to have such characteristics. For example, the inventive couplers are compatible with common coupler solvents and are efficiently reactive with oxidized photographic color developing agents to form dye. The inventive yellow dyes formed by the couplers exhibit good peak spectral absorptivity at desired wavelengths in the blue spectral region, and images formed by such dyes in photographic elements of the invention exhibit good thermal, hydrolytic, chemical, and light stabilities. The couplers and dyes of the invention do not adversely interact with other common components that may be included in photographic elements of the invention. 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     All the Structure (I) couplers of the invention contain the phosphorous-containing tris linking group of structure (II) above. 
     Each coupler molecule of the invention also contains three coupling moieties, each bonded to the tris linking group through a different one of each of the three free bonds shown in Structure (II) above. The particular coupling moieties employed are chosen depending upon the hue and other characteristics desired to be imparted to any particular photographic element of the invention. 
     In yellow-dye-forming couplers of the invention the coupling moieties in the coupler molecules have the structure (III) above. 
     In more preferred embodiments of Structure (III), the coupling moieties in the coupler molecule have the Structure (IV): ##STR9## wherein: R 1  --, Z--, M, and R 2  -- are as previously defined for Structure (III); and the free bond shown in Structure (IV) is connected to one of the three free bonds shown in Structure (II). 
     As used herein, the terms &#34;substituent&#34; and &#34;substituted&#34; are meant to denote a wide range various groups which can be chosen, as is well known in the art, depending upon the effect or lack of effect desired on various characteristics of the couplers, e.g., solubility, diffusion resistance, dye hue, dye stability, etc. Such groups include, for example: halo, e.g., chloro, bromo or fluoro; nitro; hydroxyl; cyano; and carboxyl and its salts; and groups which may be further substituted, such as alkyl, including straight or branched chain alkyl, such as methyl, trifluoromethyl, ethyl, t-butyl, 3-(2,4-di-t-amylphenoxy) propyl, and tetradecyl; alkenyl, such as vinyl and 2-butenyl; alkoxy, such as methoxy, ethoxy, propoxy, butoxy, 2-methoxyethoxy, sec-butoxy, hexyloxy, 2-ethylhexyloxy, tetradecyloxy 2-(2,4-di-t-pentylphenoxy) ethoxy, and 3-dodecyloxyethoxy; aryl such as phenyl, 4-t-butylphenyl, 2,4,6-trimethylphenyl, naphthyl; aryloxy, such as phenoxy, 2-methylphenoxy, alpha- or beta-naphthyloxy, and 4-tolyloxy; amido, such as acetamido, benzamido, butyramido, tetradecanamido, alpha-(2,4-di-t-pentyl-phenoxy) acetamido, alpha-(2,4-di-t-pentylphenoxy)butyramido, alpha-(3-pentadecylphenoxy)- hexanamido, alpha-(4-hydroxy-3-t-butylphenoxy)- tetradecanamido, 2-oxo-pyrrolidin-1-yl, 2-oxo-5-tetradecyl-pyrrolin-1-yl, N-methyltetradecanamido, N-succinimido, N-phthalimido, 2,5-dioxo-1-oxazolidinyl, 3-dodecyl-2, 5-dioxo-1-imidazolyl, and N-acetyl-N-dodecylamino, ethoxycarbonylamino, phenoxycarbonylamino, benzyloxycarbonylamino, hexadecyloxycarbonylamino, 2,4-di-t-butylphenoxycarbonylamino, phenylcarbonylamino, 2,5-(di-t-pentylphenyl) carbonylamino, p-dodecyl-phenylcarbonylamino, p-toluylcarbonylamino, N-methylureido, N,N-dimethylureido, N-methyl-N-dodecylureido, N-hexadecylureido, N, N-dioctadecylureido, N,N-dioctyl-N&#39;-ethylureido, N-phenylureido, N,N-diphenylureido, N-phenyl-N-p-toluylureido, N-(m-hexadecylphenyl)ureido, N,N-(2,5-di-t-pentylphenyl) -N&#39; -ethylureido; and t-butylcarbonamido; sulfonamido, such as methylsulfonamido, benzenesulfonamido, p-toluylsulfonamido, p-dodecylbenzenesulfonamido, p-toluylsulfonamido, p-dodecylbenzenesulfonamido, N-methyltetradecylsulfonamido, N,N-dipropylsulfamoylamino, and hexadecylsulfonamido; sulfamyl, such as N-methylsulfamyl, N-ethylsulfamyl, N,N-dipropylsulfamyl, N-hexadecylsulfamyl, N, N-dimethylsulfamyl, N-[3-(dodecyloxy)propyl]sulfamyl, N-[4-(2,4-di-t-pentylphenoxy)butyl]sulfamyl, N-methyl-N-tetradecylsulfamyl, and N-dodecylsulfamyl; carbamoyl, such as N-methylcarbamoyl, N,N-dibutylcarbamoyl, N-octadecylcarbamoyl, N-[4-(2,4-di-t-pentylphenoxy)butyl]carbamoyl, N-methyl-N-tetradecylcarbamoyl, and N,N-dioctylcarbamoyl; acyl, such as acetyl, (2,4-di-t-amylphenoxy)acetyl, phenoxycarbonyl, p-dodecyloxyphenoxycarbonyl methoxycarbonyl, butoxycarbonyl, tetradecyloxycarbonyl, ethoxycarbonyl, benzyloxycarbonyl, 3-pentadecyloxycarbonyl, and dodecyloxycarbonyl; sulfonyl, such as methoxysulfonyl, octyloxysulfonyl, tetradecyloxysulfonyl, 2-ethylhexyloxysulfonyl, phenoxysulfonyl, 2,4-di-t-pentylphenoxysulfonyl, methylsulfonyl, octylsulfonyl, 2-ethylhexylsulfonyl, dodecylsulfonyl, hexadecylsulfonyl, phenylsulfonyl, 4-nonylphenylsulfonyl, and p-toluylsulfonyl; sulfonyloxy, such as dodecylsulfonyloxy, and hexadecylsulfonyloxy; sulfinyl, such as methylsulfinyl, octylsulfinyl, 2-ethylhexylsulfinyl, dodecylsulfinyl, hexadecylsulfinyl, phenylsulfinyl, 4-nonylphenylsulfinyl, and p-toluylsulfinyl; thio, such as ethylthio, octylthio, benzylthio, tetradecylthio, 2-(2,4-di-t-pentylphenoxy)ethylthio, phenylthio, 2-butoxy-5-t-octylphenylthio, and p-tolylthio; acyloxy, such as acetyloxy, benzoyloxy, octadecanoyloxy, p-dodecylamidobenzoyloxy, N-phenylcarbamoyloxy, N-ethylcarbamoyloxy, and cyclohexylcarbonyloxy; amino, such as phenylanilino, 2-chloroanilino, diethylamino, dodecylamino; imino, such as 1 (N-phenylimido) ethyl, N-succinimido or 3-benzylhydantoinyl; azo, such as phenylazo and naphthylazo; a heterocyclic group, heterocyclic oxy group or a heterocyclic thio group, each of which may be substituted and which contain a 3 to 7 membered heterocyclic ring composed of carbon atoms and at least one hetero atom selected from the group consisting of oxygen, nitrogen and sulfur, such as 2-furyl, 2-thienyl, 2-benzimidazolyloxy or 2-benzothiazolyl; quaternary ammonium, such as triethylammonium; and siloxy, such as trimethylsiloxy. 
     The particular substituents used may be selected to attain the desired photographic properties for a specific application and can include, for example, hydrophobic groups, solubilizing groups, blocking groups, etc. Generally, the above groups and substituents thereof may typically include those having 1 to 42 carbon atoms and typically less than 30 carbon atoms, but greater numbers are possible depending on the particular substituents selected. Moreover, as indicated, the substituents may themselves be suitably substituted with any of the above groups. 
     The term &#34;alkyl&#34; or &#34;alkylene&#34; standing alone herein or as part of another term is meant to denote C 1  -C 20  alkyl or alkylene. 
     The term &#34;aryl&#34; or &#34;arylene&#34; standing alone herein or as part of another term is meant to denote C 6  -C 12  aryl or arylene. 
     In particularly preferred embodiments of yellow-dye-forming couplers of the invention containing three coupling moieties of Structure (III) above, bonded to a tris linking group of Structure (II) above: each --R-- is phenoxylene; each R 1  -- is t-butyl; each Z-- is independently ##STR10## each M-- is independently a substituted or unsubstituted sulfonamido, sulfamyl, alkoxycarbonyl, or acylamino group, with particularly preferred specific examples being ##STR11## each R 2  -- is H--. 
     Some specific examples of yellow-dye-forming couplers of the invention are illustrated in Table I, showing the tris linking group of Structure (II) and the three coupling moieties of Structure (IV) which together comprise each coupler molecule. 
     
                                           TABLE I__________________________________________________________________________CouplerTris Linking Group    Coupling Moieties__________________________________________________________________________Y-1 ##STR12##                       ##STR13##Y-2 ##STR14##                       ##STR15##Y-3 ##STR16##                       ##STR17##Y-4 ##STR18##                       ##STR19##Y-5 ##STR20##                       ##STR21##__________________________________________________________________________ 
    
     Couplers of the invention can be readily prepared by known general condensation reactions starting with appropriate known derivatives of the coupling moieties and linking group. One convenient general scheme is as follows, wherein R 1  --, R 2  --, Z--, M--, and --R-- are as described in regard to Structures (II) and (III) above. ##STR22## 
    
    
     A working example of a specific preparation of a specific coupler of the invention is as follows: 
     PREPARATION EXAMPLE 
     Coupler Y-1 of Table I ##STR23## 
     To a solution of 24.2 g (0.03 mol) of (5) in 150 mL of dried tetrahydrofuran (THF) was added with vigorous stirring 1.2 g (0.03 mol) of sodium hydride followed by the slow addition of 1.2 g (0.01 mol) of phosphorus oxychloride (7) dissolved in 50 mL of dried THF. The reaction mixture was stirred at room temperature for 3 hours then poured into ice-water containing 5 mL of concentrated hydrochloric acid. The gummy solid was separated, triturated first with methanol and then with ligroine. Separation of the resulting material by filtration under suction afforded 18 g (73.2%) of (Y-1) as a white solid. Thin layer chromatography (CH 2  Cl 2  /AcOEt: 5/1) indicated one spot material. Physical and spectroscopic data are consistent with the assigned structure. Anal. Calc&#39;d for 
     C 123  H 168  Cl 3  N 6  O 25  S 6  P: C, 60.05; H, 6.88; N, 3.42; P, 1.26. Found: C, 59.98; H, 6.85; N, 3.43; P, 1.29. 
     Dyes in accordance with the invention are those formed by well-known coupling reaction of an oxidized photographic color developing agent with a coupler, in this case a coupler in accordance with the invention. 
     The photographic elements of the invention each comprise a support having thereon a photographic silver halide emulsion layer and one or more of the new tris couplers of the invention. Such elements can contain any of the layers and components known in the photographic art, with at least one of the yellow-dye-forming couplers therein being a coupler of this invention. 
     Couplers of the invention can be used in any of the ways and in any of the combinations in which couplers are used in the photographic art. Many such ways and combinations are well known to those in the photographic art. Typically, the coupler is incorporated in a silver halide emulsion and the emulsion is coated on a support to form a photographic element of the invention. Alternatively, the coupler can be incorporated in an element of the invention at a location adjacent to the silver halide emulsion where, during development, the coupler will be in reactive association with development products such as oxidized color developing agent. Thus, as used herein, the term &#34;associated&#34; signifies that the coupler is in the silver halide emulsion layer or in an adjacent location where, during processing, the coupler is capable of reacting with silver halide development products. 
     The photographic elements of the invention can be single color elements or multicolor elements. Multicolor elements contain dye-image-forming units sensitive to each of the three primary regions of the spectrum. Each unit can comprise a single emulsion layer or multiple emulsion layers sensitive to a given region of the spectrum. The layers of the element, including the layers of the image-forming units, can be arranged in various orders as known in the art. In an alternative format, the emulsions sensitive to each of the three primary regions of the spectrum can be disposed as a single segmented layer. 
     A typical multicolor photographic element of the invention comprises a support bearing a cyan-dye-image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan-dye-forming coupler, a magenta-dye-image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta-dye-forming coupler, and a yellow-dye-image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow-dye-forming coupler, at least one of the yellow-dye-forming couplers in the element being a coupler of this invention. The element can contain additional layers, such as filter layers, interlayers, overcoat layers, subbing layers, and the like. 
     If desired, the photographic element can be used in conjunction with an applied magnetic layer as described in Research Disclosure, November, 1992, Item 34390 published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire P010 7DQ, ENGLAND. 
     In the following discussion of some suitable materials for use in the emulsions and elements of this invention, reference will be made to Research Disclosure, Issue Number 908, December, 1989, Item 308119, pages 993-1015, available as described above, which will be identified hereafter by the term &#34;Research Disclosure.&#34; The contents of the Research Disclosure, including the patents and publications referenced therein, are incorporated herein by reference, and the Sections hereafter referred to are Sections of the Research Disclosure. 
     The silver halide emulsions employed in the elements of this invention can be either negative-working or positive-working. Some suitable emulsions and their preparation as well as methods of chemical and spectral sensitization are described in Sections I through IV. Color materials and development modifiers are described in Section IX, and various additives such as brighteners, antifoggants, stabilizers, light absorbing and scattering materials, hardeners, coating aids, plasticizers, lubricants and matting agents are described, for example, in Sections V, VI, VIII, X, XI, XII, and XVI. Manufacturing methods are described in Sections XIV and XV, other layers and supports in Sections XIII and XVII, processing methods and agents in Sections XIX and XX, and exposure alternatives in Section XVIII. 
     Preferred supports are paper, cellulose acetate, and poly(ethylene terephthalate). 
     Photographic elements can be exposed to actinic radiation, usually in the visible region of the spectrum, to form a latent image and then processed to form a visible dye image. Processing to form a visible dye image includes the step of contacting the element with a color developing agent to reduce developable silver halide and oxidize the color developing agent. Oxidized color developing agent in turn reacts with the coupler to yield a dye of the invention. 
     Preferred color developing agents are p-phenylenediamines. Especially preferred are: 
     4-amino N,N-diethylaniline hydrochloride, 
     4-amino-3-methyl-N,N-diethylaniline hydrochloride 
     4-amino-3-methyl-N-ethyl-N-(b-(methanesulfonamido)ethyl)aniline sesquisulfate hydrate, 
     4-amino-3-methyl-N-ethyl-N-(b-hydroxyethyl)aniline sulfate, 
     4-amino-3-b-(methanesulfonamido)ethyl-N,N-diethylaniline hydrochloride, and 
     4-amino-N-ethyl-N-(2-methoxyethyl)-m-toluidine di-p-toluene sulfonic acid. 
     With negative working silver halide this processing step leads to a negative image. To obtain a positive (or reversal) image, this step can be preceded by development with a non-chromogenic developing agent to develop exposed silver halide, but not form dye, and then uniformly fogging the element to render the unexposed silver halide developable. Alternatively, a direct positive emulsion can be employed to obtain a positive image. 
     Development is followed by the conventional steps of bleaching, fixing, or bleach-fixing, to remove silver and silver halide, washing and drying. 
     The following example is presented to further illustrate a specific photographic element of the invention containing a coupler of the invention. 
     A comparative example is also provided containing a coupler outside the scope of the present invention. The comparative coupler employed is as follows: ##STR24## 
     EXAMPLE 1 and COMPARATIVE EXAMPLE A 
     Preparation of Photographic Elements 
     Dispersions of the couplers were prepared in the following manner: The quantities of each component are found in Table II. In one vessel the coupler, stabilizer [2,2&#39;-methylenebis(3-t-butyl-5-methylphenol)monoacetate], coupler solvent (dibutyl phthalate), and ethyl acetate were combined and warmed to dissolve. In a second vessel, gelatin, Alkanol XC™ (surfactant and Trademark of E.I. DuPont Co., USA) and water were combined and warmed to about 40° C. The two mixtures were mixed together and passed three times through a Gaulin colloid mill. The ethyl acetate was removed by evaporation and water was added to restore the original weight after milling. 
     
                                           TABLE II__________________________________________________________________________                Grams                     Grams                          Grams                              GramsDispersion Coupler      Grams           Grams                Coupler                     Ethyl                          12.5%                              Alkanol                                    GramsNumber Number      Coupler           Stabilizer                Solvent                     Acetate                          Gelatin                              XC (10%)                                    Water__________________________________________________________________________1     Y-1  1.725           0.700                0.956                     5.117                          19.20                              2.40  9.87A     C-1  1.891           0.834                1.058                     5.672                          19.20                              2.40  8.95__________________________________________________________________________ 
    
     The photographic elements were prepared by coating the following layers in the order listed on a resin-coated paper support: 
     
         ______________________________________1st Layer        3.23 g/m.sup.2Gelatin2nd LayerGelatin          1.61 g/m.sup.2Coupler Dispersion            7.0 × 10.sup.-4 mole coupling            moieties/m.sup.2AgCl emulsion    0.24 g Ag/m.sup.2 and blue-sensitized3rd LayerGelatin          1.33 g/m.sup.22-(2H-benzotriazol-2-yl)-4,6-            0.73 g/m.sup.2bis-(1,1-dimethylpropyl)phenolTinuvin 326 ™ (Ciba-Geigy)            0.13 g/m.sup.24th LayerGelatin          1.40 g/m.sup.2Bis(vinylsulfonylmethyl)ether            0.14 g/m.sup.2______________________________________ 
    
     Exposing and Processing of Photographic Elements 
     The photographic elements were given stepwise exposures to blue light and processed as follows at 35° C. 
     
         ______________________________________Developer         45 secondsBleach-Fix        45 secondsWash (running water)             90 seconds______________________________________ 
    
     The developer and bleach-fix were of the following compositions: 
     
         ______________________________________DeveloperWater                   700.00  mLTriethanolamine         12.41   gBlankophor REU ™ (Mobay Corp.)                   2.30    gLithium polystyrene sulfonate (30%)                   0.30    gN,N-Diethylhydroxylamine (85%)                   5.40    gLithium sulfate         2.70    gN-{2-[4-amino-3-        5.00    gmethylphenyl)ethylamino]ethyl}-methanesulfonamide, sesquisulfate1-Hydroxyethyl-1,1-diphosphonic                   0.81    gacid (60%)Potassium carbonate, anhydrous                   21.16   gPotassium chloride      1.60    gPotassium bromide       7.00    gWater to make           1.00    LpH at 26.7° C. adjusted to 6.7Bleach-FixWater                   700.00  mLSolution of Ammonium thiosulfate                   127.40  g(56.4%) plus Ammonium sulfite (4%)Sodium metabisulfite    10.00   gAcetic acid (glacial)   10.20   gSolution of Ammonium ferric                   110.40  gethylene-diaminetetraacetate (44%) +Ethylenediamine-tetraacetic acid(3.5%)Water to make           1.00    LpH @ 26.7° C. adjusted to 6.7______________________________________ 
    
     Photographic Tests 
     Yellow dyes were formed upon processing. The following photographic characteristics were determined: D-max (the maximum density to blue light), D-min (the minimum density to blue light), Contrast (the ratio (S-T)/0.6, where S is the density at a log exposure 0.3 units greater than the Speed value, and T is the density at a log exposure 0.3 units less than the Speed value), relative photographic speed (the relative reciprocal of exposure required to yield a density to blue light of 1.0), and Lambda-max (the wavelength of peak absorption at a density of 1.0). These values for each example are tabulated in Table III. 
     
                       TABLE III______________________________________Example  Disper- Coup-   D-   D-   Con-       Lambda-Number sion    ler     max  min  trast                                 Speed max______________________________________1      1       Y-1     2.03 0.07 2.27 188   447Comp. A  A       C-1     1.49 0.06 1.60 176   445______________________________________ 
    
     The equivalent weight of the coupler, which is important in determining the amount of coupler that must be coated, is equal to the molecular weight divided by the number of coupling moieties in the molecule. The equivalent weight advantage of the couplers of the invention is illustrated in Table IV. 
     
                       TABLE IV______________________________________Coupler Number       Molecular Weight                    Equivalent Weight______________________________________Y-1         2460         820C-1          909         909______________________________________ 
    
     The data in the Tables III and IV confirm that the couplers of the present invention provide higher coupling efficiency (Dmax, contrast and speed) than the comparative example. Also, the couplers of this invention have lower equivalent weight than the comparative coupler, thus, providing a reduction of chemical load in the coating, resulting in a thinner coating that improves transparency and optical sharpness. 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it should be appreciated that variations and modifications can be effected within the spirit and scope of the invention.