US3253924A - Two-equivalent thiocyano couplers - Google Patents

Description

United States Patent 3,253,924 v TWO-EQUIVALENT THIOCYANO COUPLERS Anthony Loria and lilnlari F. Salminen, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N .Y., a corporation of New Jersey No Drawing. Filed Feb. 8, 1965, Ser. No. 431,219 Claims. (Cl. 96-100) This invention relates to photography and particularly to compounds which form dyes on coupling with the oxidized developing agent to produce dye images.

This application is a continuing application of Loria and Salminen, U.S. Serial No. 25,233, filed April 28, 1960.

The formation of colored photographic images by the coupling of oxidized aromatic amino developing agents with color-forming or coupling compounds is well known. In these processes the substractive process of color formation is ordinarily used and the image dyes are intended to be cyan, magenta and yellow, the colors that are complementary to the primary colors. The couplers which produce the yellow dyes are ordinarily compounds containing a methylene group having two carbonyl groups attached to it. Those producing the magenta dyes are ordinarily pyrazolones and the couplers which produce the cyan dyes are usually :phenols or naphthols.' The dyes produced by coupling are azomethines, indamines or indophenols depending upon the composition of the coupler and of the developer.

Conventional color-forming coupler compounds such as the acetoacetanilides, S-pyrazolones, phenols and naphthols each have an active methylene group which reacts with oxidized color developer during color development to produce the dyes. These coupler compounds are 4-equivalent couplers because they are characterized by requiring the development of four exposed silver halide molecules in order to produce one molecule of dye from the coupling reaction between a coupler molecule and a developer molecule.

It is therefore an object of the present invention to provide a novel class of color-forming coupler compounds for color photography which are 2-equivalent, that is, couplers that require the development of only two exposed molecules of silver halide to produce one molecule of dye.

A further object of the invention is to provide a novel class of color-forming couplers which are not only 2- equivalent but which are characterized by having all the desirable features of prior art couplers from which they are produced.

A still further object is to provide silver halide emulsions containing our novel 2-equivalent coupler compounds.

Still further objects will become apparent from the following description.

These and other objects are accomplished by means of our invention as described hereinafter.

We have discovered a novel class of color-forming coupler compounds that are valuable for use in color photography. Our couplers are characterized by being 2-equivalent couplers which require the development of only two exposed silver halide molecules during color development to form one molecule of dye from a molecule of coupler and a molecule of developer.

Two-equivalent couplers have several important and distinctive advantages over the conventional or 4-equivalent couplers, for example, the amount of silver halide used in an emulsion is reduced 50%. This not only reduces the cost of producing the emulsions containing our color-forming coupler but results in improved quality of pictures made using these emulsions. The reduced silver halide emulsion requirements make possible thinner butoxy, pentoxy, hexoxy, octoxy, nonoxy, decoxy, do-.

emulsion layers. It is known that improved image definition and resolution result from reducing the thickness of emulsion layers. Reductions of emulsion thickness have the further'advantage of decreasing the optical opacity of the emulsion layer which allows more light to penetrate into emulsion layers underneath the emulsion layer containing our coupler.

Our couplers are further characterized by releasing the thiocyanate ion upon colordevelopment. It is known that the thiocyanate ion is a silver halide solvent so that its release by the couplers of our invention may be used to advantage in color development processes. It is possible to use blends of the couplers of our invention with the corresponding parent coupler in order to predeterrnine the amount of thiocyanate ion and thus the silver halide solvent effect produced by color development.

The couplers of our invention have the general formula:

wherein W represents. a coupler radical such as those having the formula:

N=C R radicals C-CH radicals, and radicals in which R represents an alkyl radical having from 1 to 32 carbon atoms which may be a normal alkyl radical having from-1 to 18 carbon atoms, e.g methyl, propyl, hexyl, octyl, dodecyl, pentadecyl, octade-cyl, etc.,, a secondary alkyl radical in which the secondary carbon atom is preferably attached directly to the carbonyl radical and has attached to it two alkyl radicals each of .Which may have from 1 to 18 carbon atoms, as defined above, provided that the. R group does not have more than a total of 32 carbon atoms, a tertiary alkyl radical in which the tertiary carbon atom is preferably attached directly to the carbonyl radical and has attached to it three alkyl radicals each of which may have from 1 to 18 carbon atoms, as defined above, provided that the R group does not have more than a total of 32 carbon atoms and in which one or two of these alkyl radicals attached to the tertiary carbon may themselves be secondary or tertiary alkyl radicals having from 1 to 18 carbon atoms, a tertiary alkyl radical in which one, two, or three of the alkyl groups defined above that are attached to the tertiary carbon atom, are replaced by alkoxy radicals having from 1 to 18 carbon atoms such as methoxy, ethoxy, propoxy,

decoxy, tridecoxy, tetradecoxy, pentadecoxy, hexadecoxy, octadecoxy, etc., or'alkoxyalkyl having from 1 to 18 carbon atoms in which the alkoxy and alkyl radicals are among those defined above such as methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, hexoxymethyl, decoxymethyl, pentadecoxymethyl, methoxypr-opyl, methoxyhexyl, methoxyoctyl, methoxydecyl, methoxydodecy-l, methoxypentadecyl, nonoxynonyl, etc. or R represents a cylclohexyl radical substituted with an' alkyl radical, an alkoxy radical, an alkoxyalkyl radical, each nonoxydecylcyclohexyl, etc., l-phenylcyclohexyl, l-t-olylcyclohexyl, etc., or R represents a bicycloalkyl radical such as a terpenyl radical, e.g., 7,7-dimethylnorbornyl, a 2 alkyl 7,7 dimethylnorbornyl, a 2-a=lkoxy 7,7 dimethylnorbornyl, a 2 alkoxyalkyl 7,7 dimethylnorbornyl, preferably although not necessarily attached to the carbonyl group through the bridgehead carbon, and

in which the alkyl, alkoxy and alkoxyalkyl substituentsmay each have from 1 to 18- carbon atoms as defined above, such as 2 methyl 7,7 dimethylnorbornyl, 2- octyl 7,7 dimethylnorbornyl, 2 octadecyl 7,7 dimethylnorbornyl, etc., Z-ethoxy 7 ,7 dimethylnorbornyl, 2 nonoxy 7,7 dimethylnorbornyl, 2 octadecoxy- 7,7 dimethylnorbornyl, etc., 2 methoxybutyl 7,7- dimethylnorbornyl, 2 octoxydecyl 7,7 dimethylnorbornyl, etc., a 2 aryl 7,7 dimethylnorbornyl such as 2 phenyl 7,7 dimethylnorbornyl, 2 tolyl 7,7 dimethylnorbornyl, etc., an aryl radical, e.g., phenyl, an alkphenyl radical in which the alkyl radical has from 1 to 18 carbon atoms, e.g., 3 methylphenyl, 2 butylphenyl, 4 octylphenyl, 2 dodecylphenyl, 3 octadecylphenyl, etc., an alkoxyphenyl radical in which the alkyl group has from 1 to 18 carbon atoms, e.g., Z-methoxyphenyl, 2 propoxyphenyl, 2 hexoxyphenyl, 2 nonoxyphenyl, 2 decoxyphenyl, 2 octadecoxyphenyl, etc., R represents an aryl radical such as phenyl, alkoxyphenyl in which the alkyl radical may have from 1 to 18 carbon atoms as defined above, for R, halophenyl radicals such as 2 chlorophenyl, 2,4 dichlorophenyl, 2,4,6-trichlorophenyl, the corresponding bromoand corresponding fluorophenyl radicals, etc., sulfonamidophenyl radicals, e.g., benzenesulfonyl N ('y phenyl npropyl) p toluidine, 2 chlorobenzenesulfonmethylanili de, 2 chlorobenzenesulfon p toluide, etc., amidophenyl, e.g., 4 [a (4 tert butylphenoxy) propionamidolphe'nyl, 4 ['a (4' tert amylphenoxy)- butyramidolphenyl, etc., an aroyl radical, e.g., benzoyl, etc., R" represents a phenyl radical, a halogen substituted phenyl radical, e.g., 2 chlorophenyl, 2,4 dichlorophenyl, 2,4,6-trichlorophenyl or the corresponding bromoand fluorophenyl radicals, alkoxyphenyl and alkphenyl in which the alkyl radical may have from 1 to 18 carbon atoms as defined above, a phenoxyphenyl radical, a cyanophenyl radical, etc., R represents an amino radical, an alkamino radical in which the alkyl group may have from 1 to 18 carbon atoms, e.g., methylamino, butylamino, dodecylamino, octadecylamino, dimethylamino, dipropylamino, dioctylamino, didodecylamino, etc., an arylamino radical, e.g., anilino, toluidino, etc., amido radicals, e.g.,

acetamido, butyramido, etc., and R" represents a halogen atom, e.g., chlorine, bromine, iodine or fluorine, a hydrogen atom, an alkyl radical having from 1 to 8 carbon atoms such as methyl, propyl, amyl, octyl, etc., or aryl, e.g., phenyl, etc.

The couplers of our invention are further illustrated by the following representative examples.

a-Benzoyl-a-thiocyanoacet-3,5-d1carboxyani11de Coupler3 O1 0 o H C-CH 01 1- (2,4,6-trichlorophenyl) -3-pentadecyl-4-thlocyano-5- pyrazolone 1- (2,4,6-trlchlorophenyl) -3- 3- 2,4-61-tert-amylphenoxyacetamldo)benzam1do] -4-th10cyano-5pyrazolone Coupler 5 1- (p-tert-bu tylphenoxyphenyl) 3-a- (p-tert-butylphenoxy) proprionamido--thlocyano-5-pyrazolone 5 Coupler 6 NE (CH2),O-C H1. (t)

s o N 1-hydr0xy-4-thiocyano-N- a- 2,4-di-tert-ainy1phenoxy butyl] 2-n aphthumide The couplers of our invention are in general prepared by reacting the parent coupler with the product of the reaction of an alkali metal or ammonium thiocyanate with bromine.

Any of the 4-equivalent color-forming couplers known in the art of color photography are used to'advantage as the parent coupler in the immediate synthesis for making our 2-equivalent couplers.

Among the couplers of our invention are those prepared from parent prior art couplers such as the following:

(a) The yellow couplers of Weissberger et al., US. 2,407,210, issued September 3, 1946, and the yellow couplers of Weissberger et a1. 2,439,352, issued April 6, 1948.

(b) The 5-pyrazolone magenta-forming couplers of Porter et al. US. 2,369,489, issued February 13, 1945, Weissberger et al. US. 2,511,231, issued June 13, 1950, Loria et al. US. 2,600,788, issued June 17, 1952, and Feniak et al. US. 2,865,748, issued December 23, 1958, and

(c) The cyan-forming phenol and naphthol couplers of Weissberger et al. US 2,474,293, issued June 28, 1949, Salminen et al. US. 2,367,531, issued January 16, 1945, and Vittum et a1. U.S. 2,369,929, issued February 20, 1945.

The preparation of specific coupler examples will further illustrate the synthesis used.

EXAMPLE I ot-Benzoyl-a-thiocyanoacetanilide Ammonium thiocyanate 7.6 g. (0.1 mole) was dissolved in 150 ml. of 95% acetic acid and the solution cooled to -18 C. To this solution was added a solution of 4 ml. of bromide (0.082 mole) in 50 ml. of glacial acetic acid while stirring. After 15 minutes, the reaction mixture was diluted with 2 volumes of water and the oil which separated was washed several times with ice water by decantation and then taken up in 125 ml. of ethyl ether. The ether solution was dried with anhydrous sodium sulfide and filtered.

To the ether solution was added all at once, 14.3 g. (0.06 mole) of a-benzoylacetanilide. The reaction mixture was stirred for 3 hours at room temperature and left to stand overnight. The product obtained on evaporation of the ether was extracted with boiling methyl alcohol, from which the u-benzoyleu-thiocyanoacetanilide crystallized as pale yellow needles. After a second crystallization from methyl alcohol, the product melted at 148-150 C.

EXAMPLE II a-Benzoylacet-3,5-dicarb0methoxyanilide A 5-liter flask fitted with a mechanical stirrer and a 6-inch Vigreux distillation column was charged with 840 g. (4.35 moles) of ethyl benzoylacetate, 2100 ml. of

xylene and 41 g. of sodium acetate. The mixture was heated to reflux and 100 ml. of xylene was distilled out. The heating was temporarily stopped and 862 g. (4.15 moles) of dimethyl S-aminoisophthalate (M.P. 178180 C.) was added to the stirred, hot reaction mixtures. The heating was then continued at such a rate that ethanol was distilled out through the column; the temperature at the head of the column was not allowed to go above C. After about 8 hours, ethanol had essentially stopped distilling, and the temperature was slowly raised to 130 C. An additional 50 m1. of distillate was collected at this point. An additional 1000 ml. of xylene was added to the mixture. It was again brought to a boil, filtered through a heated funnel and the filtrate was allowed to stand at room temperature overnight. The solid which had separated was filtered off and washed with 1 liter of xylene followed by 1 liter of methanol. It was taken up in 20 liters of boiling 90% ethyl alcohol. The solution was filtered and allowed to stand overnight at room temperature. The product was filtered 01f, washed with 2 liters of 90% ethyl alcohol, and dried. 'Eight hundred thirty-eight grams (57%) of fluffy cream-colored solid, which melted at 163165 C. was obtained.

u-Benzoy laser-3 ,5 -d icarboxyani lide Three equivalents of alcoholic KOH were added to an alcohol solution of the diester and the. mixture was stirred at room temperature overnight. Acidification with dilute hydrochloric acid and crystallization of the product from dioxane gave material melting at 240-242 C.

oa-Benzoyl-ot-thiocyanoacet-3,5-dicarb0xyanilide Ammonium thiocyanate (7.6 g.; 0.1 mole) in 250 m1. of acetic acid was treated with 4'ml.- (0.082 mole) of bromine in 50 ml. of glacial acetic acid with stirring and cooling to 1215 C. After 5 minutes, 16.4 g. (0.05 mole) of a-benzoylacet-3,5-dicarboxyanilide was added all at once and stirring continued for 3 hours at room temperature.

The reaction mixture was poured into 2 liters of ice water; the solid which formed was filtered and washed free of acetic acid and dried in a steam cabinet. Crystallized twice from methyl alcohol, the product melted at 273-5" C. (dec.).

EXAMPLE III 1-(2,4,6-trichl0r0phenyl) -3-pentadecyl-4-thi0cyanofi-pyrazolone Ammonium thiocyanate (7.6 g.; 0.1 mole) in 200 ml. of 95 acetic acid was treated with 4 ml. (0.082 mole) of bromine in 50 ml. of acetic acid with stirring at 1520 C. After 5 minutes, 9.46 g. (0.02 mole) of l-(2,4,6-trichlorophenyl)-3-pentadecyl-5-pyrazolone (prepared as described in Feniak et al. US. Serial No. 608,310) was added during 10 minutes and stirring was continued for 3 hours longer at room temperature. The reaction mixture was left to stand overnight. The yellow-brown precipitate which had formed was collected, washed free of acetic acid, and air dried.

The dry product was extracted with 400 ml. of boiling methyl alcohol in 2 portions. The combined extracts were diluted with an equal volume of hot water and the solution was allowed to cool slowly with stirring. The pinkish solid which formed was collected, washed well with cold water, and dried. It was purified by recrystallizing it from acetonitrile (charcoal) and twice from methylalcohol. The white product melted at 106 C.

Analysis:

Calculated roi- CQH34C13N3OS 56.7 6. Found 6.

EXAMPLE IV 1-(2,4,6-trichl0rophenyl) 3- [3-(2,4-di-tert-amylphenoxyacetamido) benzamido] -4-thiocyano-S-pyrazolone This coupler was prepared by a process similar to that used for Example III but in which a molecular equivalent amount of l (2,4,6-trichlorophenyl)-3-[3-(2,4-di-tertamyl phenoxyacetamido)benzamido-S-pyrazolone prepared as in Loria et al. U.S. 2,600,788, issued June 17, 1952, was used in place of 1-(2,4,6-trichlorophenyl)-3- pentadecyl-S-pyrazolone. The coupler produced by this process had a melting point of 110 C.

Analysis:

Calculated for C H NZOsS Found EXAMPLE V I-(p-tert-butylphenoxyphenyl)-3 u-(p-tert-butylphenoxy) propionamido-4-thiocyano-S-pyrazolone Calculated for C H N40 S 6. 17 Found 6. 20

EXAMPLE VI 1-hydr0xy-4-thi0cyan0-N-[u-(2,4-di-tert-amylphenoxy) butyl] -2-naphthamide A cooled solution of 7.6 g. (0.1 mole) of ammonium thiocyanate and 23.8 g. (0.05 mole) of l-hydroxy-N-[a- (2,4 di tert-arnylphenoxy)butyl]-2-naphthamide (prepared as given in Weissberger et a1. U.S. 2,474,293, issued June 28, 1949) in 300 ml. of 95% acetic acid was treated with 4 ml. (0.082 mole) of bromine in 25 ml. of glacial acetic acid. The bromine solution was added during minutes at 10-12 C. while stirring vigorously. The stirring was continued for 3 hours and the reaction mixture was allowed to come to room temperature.

After standing overnight, the orange-yellow precipitate which had formed was filtered and discarded. The filtrate was diluted with 3 volumes of cold water and stirred for 2 hours. The precipitate which formed was filtered, washed free of acetic acid, and dried. The dried product was recrystallized twice from methyl alcohol using decolorizing carbon in the first crystallization. The white solid melted at 112114 C.

Analysis:

Calculated f0! CazHqoNzOsS Found Some of our couplers'which'have lower alkyl groups as s'ubstituents are diffusible and are used advantageously in color developer solutions for developing dye images in photographic emulsions according to conventional processes.

The non-diifusing couplers of our invention are advantageously incorporated in emulsion layers of the developing-out type for color'photography. Emulsions containing our couplers are coated on transparent supports such as glass, cellulose esters, etc., or on a non-transparent reflecting material such as paper, opaque cellulose esters,

etc.

The emulsions of our invention are color developed with developer solutions containing any of the well known primary aromatic amino silver halide developing agents such as the phenylenediamines including the alkyl phenylenediamines' and the alkyl toluenediamines. These are generally used in the salt form such as the hydrochloride or sulfate. The para-aminophenols and their substituted products may also be used where the amino group is unsubstituted. All of the developing agents have an unsubstituted amino group which enables the oxidation product of the developer to couple with the color-forming coupler compounds to form the dye image.

Typical developers containing these developing agents are illustrated by the following:

DEVELOPER 1 G. 2-amino-5-diethylaminotoluene hydrochloride 2.5 Sodium sulfite (anhydrous) 5 Sodium carbonate (anhydrous) 20 Potassium bromide 2 Water to 1 liter.

DEVELOPER 2 N-ethyl-B-methanesulfonamidoethyl-3-methyl-4- aminoaniline sulfate 2 Sodium sulfite (anhydrous) .5 Sodium carbonate (anhydrous) 30 Water to 1 liter.

Our couplers are incorporated in light-sensitive silver halide emulsion layers as described in Mannes and God-owsky U.S. Patent 2,304,940 or'Jelley and Vittum U.S. Patent 2,322,027. A wide range of coupler to coupler-incorporating solvent ratios may be used. For example, this ratio may range from 1:3 to 1:0. 'The preferred range of coupler to coupler-solvent ratios is from 1:2 to 1: /2.

Any of the standard emulsion addenda may be used in the emulsions containing our couplers such as the emulsion addenda disclosed in Dann and Gates, U.S. Serial No. 797,577, filed March 6, 1959, now U.S. Patent No.

The following specific examples illustrate typical ways in which representative members of our couplers are incorporated in emulsion layers and used to produce dye images.

EXAMPLE VII Twenty-five ml. of a dispersion of 1 g. of coupler No. 3 in 2 g. of tri-o-cresylphosphate and 2.2 g. of gelatin was mixed with 2 /2 ml. of a conventional medium-speed silver halide emulsion and the mixture was coated on a suitablysubbed cellulose acetate support. After being dried, the coating was exposed under an image and developed in a developer solution having the formula of Developer No. l

'max value at 538 m but showed improved image resolv ing power and image definition.

9 EXAMPLE VIII A light-sensitive silver halide emulsion coating prepared as in Example VII was exposed under an image and developed in a developer composition having the formula of Developer No. 2 to form a negative silver and magenta dye image. After removal of the silver image and residual silver halide according to the method used in Example VII, a good magenta dye image was left having a A max value of .5 36 m This image also had excellent resolving power and definition.

EXAMPLE IX A light-sensitive silver halide emulsion coating was prepared as in Example VII but containing 1 g. of Coupler No. 4 and 0.5 g. of tri-o-cresylphosphate instead of l g. of Coupler No. 3 and 2 g. of tri-o cresylphosphate. This emulsion coating .was exposed and processed as in Example VII to produce a magentadye image having a A max value of 538 m This image also showed good resolving power "and definition characteristics.

EXAMPLE X vA light-sensitive silver halide emulsion coating prepared as in Example VH was made containing Coupler No. 5 in place of Coupler No. 3. This was exposed and processed according to the method used in Example VII to produce a good magenta dye image having a A max value of 549 [In/L. This magenta image also had good definition and excellent resolving .power.

EXAMPLE XI A light-sensitive silver halide emulsion coating was prepared in a similar manner to the emulsion coating of Example VII but in which 1 g. of Coupler No. 6 and 0.5 g. oat di-n-butylphthalate was used in place of Coupler No. 3 and tri-o-cresylphosphate. After exposure to an image and processing according to the method of Example VII, a good cyan dye image was produced having a A max value of 700 III/L.

EXAMPLE XII A photographic emulsion coating prepared as in Example XI was exposed and developed in a developer having the formula of Developer No. 2 then bleached and fixed as in Example VII to produce a cyan dye image having good definition and resolving power and a k max value of 690 m The novel Z-equivalent dye-forming thiocyano couple-rs of our invention are valuable for use in color photography. Some of them are advantageously used in color developer solutions while the other couplers of our invention are advantageously incorporated in light-sensitive silver halide emulsion layers for color photography. In addition to having the advantages of the prior art parent couplers from which they are made, our couplers are characterized by requiring only one-half of the amount of silver halide that conventional couplers require in emulsion layers to produce equivalent dye images. Photographic emulsions containing our color forming couplers or photographic emulsions developed in color developers containing our couplers are characterized by being considerably thinner than coresponding emulsions containing or used with prior ant couplers. The thinner emulsion coatings which are made possible by use of our coloraforming couplers are very effective in color photography since they make possible the production of images of improved resolving power and definition. In addition to these advantages, the reduced optical opacity of thinner emulsion layers allows more light to penetrate into emulsions coated under our emulsion which makes it possible to produce photographic products of higher speed.

The invention has been described in detail with particular reference to preferred embodiments thereof but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We "claim:

1. A silver halide emulsion containing a color-forming coupler having the formula:

wherein W represents a coupler radical selected from those of the class consisting of RN radicals C C H II I radicals, and radicals RI!!! in which R represents a radical selected from the class consisting of "alkyl radicals having from 1 to 32 carbon atoms, cycloalkyl radicals, bicycloalkyl radicals, phenyl radicals, alkphenyl radicals in which the alkyl group has from 1 to 18-carbon atoms, and alkoxyphenyl radicals in which the alkyl group has from 1 to -18 carbon atoms, R represents a radical selected from the class consisting of phenyl radicals, carboxyphenyl radicals, alkoxyphenyl radicals, halophenyl radicals, sulfonamidop'henyl radicals, amidophenyl radicals, and aroyl radicals, R" represents a radical selected tfrom the class consisting of phenyl radicals, cyanophenyl radicals, halophenyl radicals, alkphenyl radicals in which the alkyl radical has from 1 to 6 carbon atoms, alkoxyphenyl in which the alkyl radical has from 1 to 6 carbon atoms and phenoxyphenyl radicals, R represents a radical selected from the class consisting of alkyl radicals having from 1 to 18 carbon atoms, caubamyl radicals, amino radicals, alkamino radicals, phenylamino radicals, and amido radicals, and R"" represents a radical selected from the class consisting of halogen atoms, hydrogen atoms, alkyl radicals having from 1 to 8 carbon atoms and aryl radicals.

2. A silver halide emulsion containing a color-forming coupler having the formula:

in which R represents a radical selected from the class consisting of alkyl radicals having from 1 to 32 carbon atoms, cycloalkyl radicals, bicyclo'alkyl radicals, phenyl radicals, alkphenyl radicals in which the alkyl group has from 1 to 18 carbon atoms, and alk-oxyphenyl radicals in which the alkyl group has [from 1 to 18 carbon atoms, and R represents a radical selected from the class consisting of phenyl radicals, carboxyphenyl radicals, alkoxyphenyl radicals, halophenyl radicals, sulfonamidophenyl radicals, amidop-henyl radicals and ar oyl radicals.

3. A silver halide emulsion containing a color-forming coupler having the formula:

in which R" represents a radical selected from the class consisting of phenyl radicals, cyanophenyl radicals, halophenyl radicals, alkp henyl radicals in which the alkyl radical has from 1 to 6 carbon atoms, alkoxyphenyl in l 1 which the alkyl radical has from 1 to 6 carbon atoms and phenoxyphenyl radicals, and R represents a radical selected from the class consisting of alkyl radicals having firorn 1 to 18 carbon atoms, carbamyl nadicals, amino radicals, alkamino radicals, phenylamino radicals, and amido radicals.

4. A silver halide emulsion containing a color-forming coupler having the formula:

I SON in which R' represents a radical selected from the class consisting of alkyl radicals having from 1 to 18 carbon atoms, carbamyl radicals, amino radicals, alkamino radicals, phenylamino radicals, and amido radicals, and 'R represents a radical selected from the class consisting of halogen atoms, hydrogen atoms, alkyl radicals having from 1 to 8 carbon atoms and aryl radicals.

5. A silver halide emulsion containing a color-forming coupler having the formula:

phenoxy) butyl] -2-11a1phfihalmide.

. oN in which R represents a radical selected from the class consisting of alkyl radicals "having irom 1 to 18 carbon atoms, carbamyl radicals, amino radicals, alkamino radicals, phenylamino radicals, and amido radicals.

6. A silver halide emulsion containing a color-forming coupler u-benzoyl-a-thiocyanoacetanilide.

7. A silver halide emulsion containing a color-forming coupler l-(2,4,6-trichlorophenyl) 3 pentadecyl-4- thiocyano-S-rpyrazolone.

8. A silver halide emulsion containing a color-forming coupler 1-(2,4,6-trichlorophenyl)-3-[3-(2,4-di-tertamylphenoxyacetamido)benzamido] 4 thiocyano 5- pyrazolone.

9. A silver halide emulsion containing a color-forming coupler l-(p tert butylphenoxyphenyD-3-a-(p-tertbutyl-phenoxy)ipropionamiclo-4thiocyano-5-pyrazolone.

10. A silver halide emulsion containing a color-forming coupler 1-hydroxy-4-thiocyano-N-[u-(l,4-di-tert-arnyl- No references cited.

NORMAN G. TORCHIN, Primary Examiner. J. T. BROWN, Examiner.

Claims (1)

1. A SILVER HALIDE EMULSION CONTAINING A COLOR-FORMING COUPLER HAVING THE FORMULA: