US3619196A - Light-sensitive color-photographic emulsions - Google Patents

Abstract

WHEREIN R1 is a hydrogen atom or a methyl group; R2 is a hydrogen atom or an aliphatic hydrocarbon residue having one to 16 carbon atoms; R3 is an aliphatic hydrocarbon residue having one to 18 carbon atoms; n is zero or 1; and X is a hydrogen atom, a halogen atom, or a substituted or unsubstituted phenylazo group.

A light-sensitive silver halide color-photographic emulsion, characterized by containing a cyan coupler represented by the general formula

Description

United States Patent 72] Inventors Masakuni Iwama;

lsaburo lnoue; Yutaka Takei; Toshihiko Yamamoto; Takayo Endo, Tokyo, all of Japan 21] Appl. No. 868,579

22] Filed Oct. 22, 1969 45] Patented Nov. 9, 1971 73] Assignee Konishiroku Photo Industry Co., Ltd.

Tokyo, Japan 32] Priority Oct. 24, 1968 33] Japan 54] LIGHT-SENSITIVE COLOR-PHOTOGRAPHIC EMULSIONS 6 Claims, No Drawings 52] US. Cl 96/100, 96/55, 260/202, 260/471 A 51] Int. Cl G03c l/40 50] Field of Search 96/ l 00 56] References Cited UNITED STATES PATENTS 2,375,344 5/1945 Bruylants et a1. 96/100 2,474,293 6/ l 949 Weissberger et a1 96/100 1,562,528 7/1951 Corner 96/100 1,418,129 12/1968 Kimura et a1. 96/100 3,459,552 8/1969 Yoshida et a1. 96/100 3,481,741 12/1969 Yoshida et a1. 96/100 3,488,193 1/1970 Eynde et a1. 96/100 Primary Examiner.lohn T. Goolkasian Assistan! Examiner-George W. Moxon, ll Attorney-Waters, Roditi, Schwartz and Nissen ABSTRACT: A light-sensitive silver halide color-photographic emulsion, characterized by containing a cyan coupler represented by the general formula wherein R is a hydrogen atom or a methyl group; R is a hydrogen atom or an aliphatic hydrocarbon residue having one to 16 carbon atoms; R, is an aliphatic hydrocarbon residue having one to 18 carbon atoms; :1 is zero or 1; and X is a hydrogen atom, a halogen atom, or a substituted or unsubstituted phenylazo group.

This invention relates to light-sensitive color-photographic emulsions containing novel cyan couplers which are soluble in water-immiscible high-boiling solvents.

As couplers for use in light-sensitive color-photographic emulsions, there are known the so-called Agfa type couplers which are soluble in water, and the so-called protected couplers which are soluble in water-immiscible high-boiling solvents It is well known that dye images obtained by colordeveloping protected couplers contained in the emulsion layers of light-sensitive color-photographic materials have, in general, excellent stability to light, heat, humidity and chemicals for development as compared with those of the Agfa type couplers.

Heretofore, various compounds have been synthesized for use as protected couplers. Almost all of these, however, have disadvantages in that they are low in solubility for high-boiling solvents, they easily deposit in emulsions and coatings, the starting materials therefor are expensive, and the procedures for the synthesis thereof are complex which make them expensive. For example, the coupler of the formula i tCsHu which is disclosed in U.S. Pat. No. 2,474,293, has excellent solubility for high-boiling solvents. This coupler, however, uses a very expensive starting material and is only difficulty purified. A coupler synthesized from a higher fatty acid or higher aliphatic amine, e.g. the coupler ofthe formula wherein R is a hydrogen atom or a methyl group; R is a hydrogen atom or an aliphatic hydrocarbon residue having one to 16 carbon atoms; R;, is an aliphatic hydrocarbon residue having one to 18 carbon atoms; n is zero or I; and X is lhydrogen atom, a halogen atom or a substituted or unsubstituted phenylazo group.

These couplers which are used in the present invention, can overcome the disadvantages of the conventional couplers by displaying the following characteristics:

(CHDa a I. They are easily soluble in such high-boiling solvents as dibutyl phthalate, tricresyl phosphate and N ,N-dibutyl laurylamide, so that the amounts of high-boiling solvents to be added to the couplers can be decreased and stable dispersions of high concentration can be obtained.

2. They are low in melting point and do not deposit in emulsions or in coatings. r

3. They can be synthesized by a short process, they can be easily separated and purified, they are high in yields and are inexpensive in production costs.

4. They give dye images which have desirable spectral absorption characteristics and are fast to light, heat, humidity and chemicals.

Thus, the couplers employed in the quite useful as protected couplers.

Accordingly, light-sensitive color-photographic emulsions incorporated with the couplers of the present invention can be maintained stably without any deterioration in photographic characteristics due to deposition of the couplers.

present invention are Typical couplers employed in the present invention are set forth below, but these are mere examples and the couplers usable in the present invention are not limited only to these.

(1) N-Dodecyloxycarbonyl-mo bi1OX \Ci1li)Oll \l me thy l- 1-hydroxy-2-nap hthamido COHNCHgCOOCHgCOOCuIIss (.\1.l. 74-74.5C.)

(2) N[1-(ethoxyearbonyl)pentadecyloxycarbonylmethyl]-1-hydroxy-2-naphthamido COIINCII C O ()(IUIC O O CglI (M. P. 575!lC.)

( u cv (4) N-[1-(dodecyloxycarbonyl)-cthoxycarbonylmothyl] l-hydroxy-2-naphthamide on oouNcmo0031110000211 my. 55 we.) J n,

(6) N-[l-(dodecyloxycarbonyl-motlloxycurl)onyl)- ethyl]-1-h vdroxy-2-napht llzunido (7) N -[2-(dodecyloxycarbonyl-methoxycarbonyl)- ethyl]-l-hydroxy-2-naphthamide l \-c OHNCHzCHzC o CHzC 000121125 (M.P. e 0.)

(8) N -dodecy10xycarbonyl-methoxycarbonylmethyl- 1-hydroxy-4-ehloro-2-naphthamide (9) N-dodecyloxycarbonyl-methoxycarbonylmethyll-hydroxyl- (Z-acetylphenylaz 0) -2-naphtharnide @3-0 OHNCH C O O CH COOCuHzs (M.P. 133137C l COCH:

(1 O) N-[ 1- (dodecyloxycarbonyl) -et;hoxycarbony1- methyl1-l-hydroxy-4- Z-acetylp henylaz 0) -2 naphthamide ,-ooHN c1120 0 0 mo 0 0 (3121125 (M.P. los aon o.)

| COCH:

(1 1) N-[ l-(butoxycarbonyl) -heptyloxycarbonylmethyl]-1-hydroxy-4-(Z-acetylphenylazo)-2- naphthamide COCH:

(13) N-[2-(dodecyloxycarbonyl-mcthoxycarbonyl)- ethyll-l-hydr0xy-4-(2-ethoxycarbonylphenylazo)-2- naphthamide COHNCHZCHZCOOCI'DCOO CizHes (M.P 137138 C.)

l COOC5H (14) N-[(l-methylheptyl)-0xycarbonyl methoxycarbonylmcthyl) ]-1-hydr0xy-4-( 2-ethoxycarbonylphenylazo)-2-naphthamide COOC IL;

wherein X, R and as defined above. and then this intermediate is formed into a potassium salt and is reacted in dimcthylformamide with an alkyl ester of an u-halo-fatty acid or said intermediate is reacted in dimethylformamide with an alkyl ester of halo-fatty acid in the presence of acidic potassium carbonate.

Synthesis of the couplers is exemplified below in detail. Synthesis of the coupler l) a. l-Hydroxy-Z-naphthoylglycine 84 g. of potassium hydroxide are dissolved in a mixed solution of200 ml. ofwater and 400 ml. ofalcohol and further I 12 g. of glycine are dissolved therein. To the resulting solution are added 164 g. of phenyl-l-hydroxy-Z-naphthoate and 400 ml. of alcohol and the solution is boiled under reflux for 3 hours. The solution is poured into 3 kg. of ice water and then filtered in an ordinary manner with activated charcoal. To the filtrate are added 160 ml. of concentrated hydrochloric acid and the precipitate separated thereby is filtered with suction. washed with water and pressed. The wet precipitate is then taken up in 2 liters of alcohol and boiled under reflux to completely dissolve. The resulting solution is filtered in an ordinary manner with activated charcoal. The filtrate together with 3 liters of warmed water is allowed to stand and the resulting crystals are filtered with suction, washed with 30 percent alcohol and dried to give g. of pale orange needle crystals melting at 207-209 C.

In the analogous manner, the following are obtained:

granulated sugarlike crystals of pale pink l-Hydroxy-Z-naphthoyl-/3-alanine m.p. l49l50 C.; needle crystals of pale pink b. Dodecyl-a-chloroacetate 94.5 g. of a-chloroacetic acid and 186.3 g. of dodecyl alcohol are dissolved in L5 liters of dehydrated benzene. The solution added with 5 g. of p-toluenesulfonic acid is boiled under reflux for 2 to 3 hours and the water produced during the reaction is eliminated by azeotropic distillation with benzene. The reaction solution is then shaken with aqueous sodium carbonate solution and the benzene layer is dehydrated and distilled under reduced pressure to remove the benzene. Distillation of the residue gives 155 g. of dodecyl-a-chloroacetate boiling at 187188 C./l4 mm.Hg. This product may be used in the subsequent reaction stage even after benzene is distilled off without effecting further distillation.

In an analogous manner, the following are obtained:

l-Methyl-heptyl-a-chloroacetate b.p. l20-l23 C./l3

mm.Hg.

Dodecyl-a-bromopropionate b.p. (decomp.); used without distillation Butyl-a-bromo caproate used without distillation c) N-Dodecyloxycarbonyl-methoxycarbonylmethyl l hydroxy-2-naphthamide 123 g. Of I-hydroxy-2-naphthoylglycine are dissolved in 600 ml. of methanol and mixed with a solution of 56 g. of potassium hydroxide in 600 ml. of methanol. Methanol is distilled off under reduced pressure. The residue is added with 1 liter of dimethylformamide and l3] g. of dodecyl-achloroacetate and the mixture is heated with stirring for 2 hours at a bath temperature of 95100 C. After standing to cool, the reaction mixture is poured into 10 liters of water and the separated precipitate is filtered with suction, washed with water and dried. Recrystallization from 1.5 liters of methanol gives 200 g. of the product and further recrystallization from 5 liters of n-hexane gives 170 g. offlake crystals of pale pink.

In an analogous manner, the afore-said couplers (2)(7) are obtained. Synthesis ofthe coupler (8) 188 g. Of the coupler (l), N-dodecyloxycarbonyl-methoxycarbonylmethyl-l-hydroxy-Z-naphthamide, are dissolved in 500 ml. of chloroform. The resulting solution is cooled to below C. and mixed'with a mixed solution of 66 g. of sulfuryl chloride and 200 ml. of chloroform. The solution is then allowed to stand at room temperature for 1 hour and solvent is removed by the distillation under reduced pressure. The residue is mixed with 1 liter of n-hexane and allowed to stand. The separated precipitate is filtered with suction, washed with n-hexane and dried to give 13 g. of N-dodecyloxycarbonylmethoxycarbonylmethyl-l-hydroxy-4-chloro-2-naphthamide. Recrystallization from 1.3 liters of n-hexane gives 90 g. of powderly crystals of pale brown, melting at 69-70 C. Synthesis of the coupler (9) H3 g. Of o-aminoacetophenone are dissolved in diluted hydrochloric acid and diazotized with an aqueous sodium nitrite solution. The resulting solution is added to a solution of 471 g. of the coupler l N-dodecyloxycarbonyl-methoxycarbonylmethyl-l-hydroxy-Z-naphthamide in a mixed solution of 4 liters of pyridine and 10 liters of acetonitrile at a temperature below 10 C. with stirring. Stirring is continued for 30 minutes at room temperature and 400 ml. of concentrated hydrochloric acid is added to the reaction solution and the separated precipitate is filtered with suction, washed with water and dried to give 550 g. of N-dodecyloxy-carbonylmethoxycarbonylm ethyl- I -hydroxy-4-( 2-acetylphenylazo-2- naphthamide. Recrystallization from ethyl acetate gives 3 l 0 g. of featherlike red crystals.

in the above process, use of the couplers (4), (5) and (6) in place of the starting coupler (1) provides the aforesaid couplers (10),(l l and 12), respectively.

The couplers (l3) and (I4) can be obtained from diazotized ethyl o-aminobenzoate and the couplers (3) and (7), respectively.

Among the couplers employed in the present invention. those in which X is a halogen atom can be synthesized by treating a coupler, in which X is a hydrogen atom, with a halogenating agent such as sulfuryl chloride, thereby substituting the hydrogen atom with a halogen atom. Further, those in which X is a substituted or unsubstituted phenylazo group are synthesized by coupling a coupler, in which X is a hydrogen atom, with a substituted or unsubstituted aromatic diazonium compound.

Couplers of the aforesaid formula, in which R, and R are hydrogen atoms and R is a straight chain alkyl group, show excellent solubility for high-boiling solvents. However, they can be markedly enhanced in solubility by changing R to a methyl group; R to an alkyl group; R to a branched alkyl group; or n to l. R, can be changed by selecting, as the starting material, glycine, a-alanine or B-alanine; R by selecting a chloroacetic acid, a-bromopropionic acid, a-bromo-n-butyric acid, a-bromo-i-butyric acid, a-bromocaprylic acid or crbromolauric acid; R,, by selecting lauryl alcohol, 2-ethylhexyl alcohol, 2-octyl alcohol or 7-ethyl-2-methyl-undecyl alcohol- 4; ,and n by selecting glycine or B-alanine. All these starting materials are easily obtainable, commercially available products. in the preparation of intermediate also, alkyl esters of the a-halo-fatty acids are obtained by reacting an a-halofatty acid with an equimolar amount of an aliphatic alcohol and can be synthesized with such high purity and yield. Further, the reaction of this intermediate with l-hydroxy-Z naphthoyl-amino acid can also be carried out easily as mentioned previously, and the desired product can be obtained with high purity and yield by simple isolation and purification operations.

Thus, the couplers employed in the present invention have such advantages that they can be synthesized through three and four steps, without necessitating any complex steps, from inexpensive and easily obtainable starting materials and can be greatly reduced in production costs as compared with conventional couplers.

Using the couplers synthesized in the above manner, lightsensitive color-photographic materials are prepared in the following manner:

For example, a cyan coupler employed in the present invention is dissolved in a high-boiling solvent having a boiling point of more than C. such as tricresyl phosphate or dibutyl phthalate, either singly or, if necessary, in admixture with a low-boiling solvent such as butyl acetate or butyl propionate. This solution is mixed with an aqueous gelatine solution containing a surface active agent and is then emulsified by means of a high speed rotary mixer or a colloid mill. Then, the thus formed coupler dispersion is directly added to a silver halide photographic emulsion, which is coated onto a film base, a baryta paper or the like support, following by drying to remove a major proportion of the low-boiling solvent. Alternatively, the above-mentioned coupler dispersion is set and then extruded to noodle form, which is freed from the lowboiling solvent by water-washing or the like means. Then the noodle is added with warming to a silver halide photographic emulsion, which is then coated onto the aforesaid support, followed by drying.

The above-mentioned manner of incorporation of the coupler are merely illustrative and are not limitative. The'amount of the coupler to be added to the silver halide photographic emulsion is preferably in the range of lO-lOO g. per mole of silver halide, but is not always limited thereto. As the silver halide employed in the photographic emulsion. there may be used such silver salts as silver chloride, silver iodide or silver iodobromide. This emulsion may contain chemical sensitizers, e.g. sulfur sensitizers, natural sensitizers present in gelatine, reductive sensitizers and noble metal salts. The emulsion may further contain ordinary photographic additives such as, for example, antifoggants, stabilizers, antistain agents, antiirradiation agents, coating aids, and other high molecular additives. Furthermore, it may contain known carbocyanine dyes, merocyanine dyes, etc. as optical sensitizers.

The thus obtained light-sensitive color-photographic material is exposed to radioactive rays, X-rays, visible rays, infrared rays, etc., is developed with a color-developing solution containing a p-phenylene-diamine type developer and is then bleached and fixed to obtain a cyan dye image favorable in transparency and high in resistance to light, heat and humidity. The dye image is excellent in spectral absorption characteristics and has a maximum absorption in the vicinity of 680-690 m,u. Alternatively, when a light-sensitive colorphotographic material incorporated with an arylazo type coupler, which itself has a reddish orange or red color as in the case of the coupler (l) exemplified previously, is exposed and is then treated according to the ordinary color development process, there are simultaneously obtained a cyan color negative image and a reddish orange to red color positive image. This positive color image serves, in printing the negative image onto a positive material, as a mask for correcting the undesirable absorptions in blue light and green light regions which are characteristic of the cyan color negative image. Preferable as couplers of this type are substituted phenylazo compounds having in the position ortho to the azo linkage, an alkoxycarbonyl group or a fatty acyl group.

Typical developing agents employed in developing the lightsensitive color-photographic materials of the present invention include sulfates, sulfites and hydroehlorides of N,N- diethyl-p-phenylenediamine, N-ethyl-N- B-methane-sulfonamidoethyl-3-methyl-4-aminoaniline, N-ethyl-N-hydroxyp-phenylenediamine N-ethyl-N-hydroxy-2-methyl-p-phenylenediamine and N,N-diethyl2-methyl-p-phenylenediamine.

The present invention is illustrated in further detail below with reference to examples, but it is needless to say that the examples are merely illustrative and the invention is not limited thereto.

EXAMPLE 1 20 g. of the previously exemplified coupler (l) were added to a mixed liquid comprising 20 ml. of dibutyl phthalate and 60 ml. of butyl acetate, and the mixture was completely dissolved at 80 C. This solution was mixed with 10 ml. of a 10 percent aqueous solution of Alkanol B (alkyl naphthalene sulfonate produced by Du Pont) and 200 ml. ofa 5 percent aqueous gelatine solution, and the mixture was subjected to a colloid mill to form a coupler dispersion. This coupler dispersion was added to 1 kg. of a high speed gelatinous silver iodobromide emulsion, which was then coated onto a film base and was dried to prepare a light-sensitive color-photographic material having a stable coating layer.

The thus prepared light-sensitive material was exposed according to an ordinary procedure and was then developed at 20 C. for minutes with a developing solution of the following composition:

N,N-Diethyl-p-phenylenediamine hydrochloride 2.5 g. Anhydrous sodium sulfite 2.0 g. Sodium carbonate (monohydrate) 82.0 g. Potassium bromide 2.0 3. Water to make I000 ml.

Potassium ferricyanide 100 g. Potassium bromide 50 g. Water to make 1000 ml.

The bleached material was further washed with water for 5 minutes and was then fixed for 5 minutes with a fixing bath having the following composition:

Sodium thiosulfale (pentahydrale) Water to make 250 g. 1000 ml.

Thereafter, the fixed material was washed with water for -25 minutes and was then dried to obtain a brilliant cyan dye image having a maximum absorption at 685 mu.

EXAMPLE 2 10 g. of the exemplified coupler (8) were added to a mixed liquid comprising 10 ml. of tricresyl phosphate and 30 ml. of butyl acetate, and the mixture was completely dissolved at 60 C. This solution was mixed with 5 ml. ofa 10 percent aqueous solution of the following composition: 1

Melhol 3.0 g. Anhydrous sodium sulfite 60.0 g. Hydroquinone 6.0 g. Anhydrous sodium carbonate 50.0 g. Potassium bromide l.0 g.

Water to make Subsequently, the developed material was subjected to ordinary stopping and film-hardening treatments and to waterwashing. After subjecting it to second exposure by means ofa white light,- the material was developed at 20 C. for 12 minutes with a developing solution of the following composition: 1

N.N-Diethyl-p-phenylenediaminc hydrochloride 5.0 Anhydrous sodium sulfite 2.0 g. Sodium carbonate (monohydrate) 82. 1. Potassium bromide l.0 g. Water to make I000 ml.

Thereafter, the material was subjected to ordinary stopping, fixing. water-washing and bleaching treatments, was washed with running water for 20 minutes and was then dried to obtain a brilliant cyan color positive image having a maximum absorption at 685 mu.

EXAMPLE 3 10.0 g. of the exemplified coupler (4) were mixed with 20 ml. of dibutyl phthalate, and the mixture was completely dissolved at 50 C. This solution was mixed with 5 ml. ofa l0 percent aqueous solution of Alkanol B and 200 ml. ofa 5 percent aqueous gelatine solution, and the mixture was passed several times through a colloid mill to form a dispersion. The disper sion was added to 500 g. of a gelatinous silver chlorobromide emulsion, which was then coated onto a baryta paper and was dried to prepare a light-sensitive color-photographic material.

The thus prepared light-sensitive material was exposed and then developed at 20 C. for 10 minutes with a developing solution ofthe following composition:

N-Ethyl-Nhydroxyethyl-pphenylenediaminc sulfate 25 g. Anhydrous sodium sulfite 2.0 g. Hydroxyaminc hydrochloride 1.0g Sodium carbonate (monohydratc) 810g. Potassium bromide 2.0 g.

Water to make I000 ml.

Subsequently, the material was dipped in a stopping bath comprising 10 ml. of glacial acetic acid, 3.0 g. of caustic soda and 1000 ml. of water, and was then immediately dipped for 4 minutes in an acidic. film-hardening fixing bath. Subsequently, the material was washed with water for 10 minutes and was bleached at 20 C. for 8 minutes in a bath of the following composition:

EDTA ZNa (disodium salt of ethylencdiamine tetraacclic acid) 40.0 g. Ferric chloride 30.0 g. Sodium carbonate (monohydrate) 20.0 Potassium bromide 30.0 g. Sodium thiosulfate (pentahydrate) 200.0 Water to make I000 ml.

After washing with water for 20 minutes, the bleached material was dipped in a stabilizing bath for 2 minutes and then dried to obtain a cyan color image having a maximum absorption at 685 mp. which was favorable in resistance to light and heat and was excellent in stability.

EXAMPLE 4 2.0 g. of the exemplified coupler (10) were added to a mixed liquid comprising 2 ml. of dibutyl phthalate and 6 ml. of butyl acetate, and the mixture was dissolved at 80 C. This solution was mixed with 1 ml. ofa 10 percent aqueous solution of Alkanol B and 20 ml. of a percent aqueous gelatine solution, and the mixture was subjected to a colloid mill to form a coupler dispersion. The coupler dispersion was added to 100 g. of a high speed gelatinous silver iodobromide emulsion, which was then coated onto a film base and dried to prepare a high-sensitive color-photographic material.

The thus prepared light-sensitive material was exposed according to an ordinary procedure and was then treated with the same developing solution as in example 1 to obtain a red positive image having a maximum absorption at 500 mp. and a cyan color image having a maximum absorption at 685 mu.

EXAMPLE 5 2.0 g. of the exemplified coupler (7) were dissolved in 5 ml. of butyl acetate. This solution was mixed with 1.5 ml. ofa percent aqueous solution of Alkanol B and 20 ml. of a 5 percent aqueous gelatine solution, and the mixture was subjected to a colloid mill to form a coupler dispersion. The coupler dispersion was added to 100 g. of a red color-sensitive, high speed gelatinous silver iodobromide emulsion, which was then coated onto a film base and dried to prepare a light-sensitive color-photographic material. The thus prepared light-sensitive material was exposed according to an ordinary procedure and was then developed with the same developing solution as in example 1 to obtain a brilliant cyan color image having a maximum absorption at 685 mu.

EXAMPLE 6 5.0 g. of the exemplified coupler (2) were added to a mixed liquid comprising 5.0 ml. of dibutyl phthalate and ml. of butyl acetate, and the mixture was dissolved at 60 C. This solution was mixed with 2.5 ml. of a 10 percent aqueous solution of Alkanol B and 50 ml. of a 5 percent aqueous gelatine solution, and the mixture was subjected to a colloid mill to form a coupler dispersion. The coupler dispersion was added to 500 g. of a red sensitized silver chloride emulsion, which was then coated onto a film base and dried.

On the other hand, 5.0 g. of a-[3-(2,4-di-tertamyl-phenoxyacetamide)-benzoyll-2-methoxy-acetanilide were dissolved and mixed with a gelatine solution in the same manner as above to form a dispersion. The dispersion was added to 500 g. of a silver bromide emulsion, which was then coated onto the above-mentioned coating to prepare a light-sensitive color-photographic material.

The thus prepared light-sensitive material was exposed to X-rays according to an ordinary procedure, was developed at C. for 10 minutes with the same developing solution as in example I, and was subjected to ordinary stopping and filmhardening treatments andto water-washing. After subjecting to second exposure by means of a yellow light (using Agfa color Separation Filter L exposure time 30 seconds), the material was again developed at 20 C. for 10 minutes with the above-mentioned developing solution, was subjected to ordinary stopping, fixing, bleaching and water-washing treatments, and was then dried to obtain a yellow color image with a blue background.

EXAMPLE 7 5.0 g. of the exemplified coupler (5) were added to a mixed liquid comprising 5.0 ml. of dibutyl phthalate and l5 ml. of butyl acetate, and the mixture was completely dissolved by heating to 60 C. This solution was mixed with 2.5 ml. ofa 10 percent aqueous solution of Alkanol B and 50 ml. of a 5 percent aqueous gelatine solution, and the mixture was subjected to a colloid mill to form a coupler dispersion. The coupler dispersion was added to 500 g. of a high speed silver iodobromide emulsion, which was then coated onto a film base and dried to prepare a light-sensitive color-photographic material.

On the other hand, a gelatine layer having a thickness of about 5 u was formed on a cellulose triacetate film base. Onto said gelatine layer was spotted a thymidine solution, which had been labeled with tritium so that the amount thereof corresponded to 10 ac. per cm Thereafter, spotting was repeated by doubling diluting of the said solution to form a standard radioactive source with a stepwedge 0N2 with respect to radioactivity.

The surface of this gelatine film was brought in close contact with the film surface of the above-mentioned light-sensitive color-photographic material. After allowing it to stand for 15 hours, the light-sensitive material was subjected to the same development as in example I to obtain a brilliant cyan dye image showing the presence of radioactive substance at the portion corresponding to the radioactive source.

What we claim is:

l. A light-sensitive silver halide color-photographic emulsion, comprising a cyan coupler represented by the general formula wherein R, is a hydrogen atom or a methyl group; R is a hydrogen atom or an aliphatic hydrocarbon residue having one to 16 carbon atoms; R is an aliphatic hydrocarbon residue having one to l8 carbon atoms; n is zero or 1; and X is a hydrogen atom, a halogen atom, or a substituted or unsubstituted phenylazo group.

2. A light-sensitive silver halide color-photographic emulsion as claimed in claim 1, in which said cyan coupler is N-[ l- (Dodecyloxycarbonyl-methoxycarbonyl) -ethyl]-l-hydroxy2 -naphthamide of the formula COHNCIIC ()OCII C O ()C13II35 3. A light-sensitive silver halide color-photographic emulsion as claimed in claim 1, in which said cyan coupler is N- [2(Dodecyloxycarbonyl-methoxycarbonyl) -ethyl] 1 -hydroxy- 2-naphthamide of the formula l 3-o oIINomomc o o cmo o o Gully,

4. A light-sensitive silver halide color-photographic emulsion as claimed in claim 1, in which said cyan coupler is N- Dodecyloxycarbonyl-methoxycarbonylmethyll -hydroxy-4- chloro-2naphthamide ofthe formula 11 2. 5. A light-sensitive silver halide color-photographic emul- 6. A light-sensitive silver halide color-photographic emulsion as claimed claim 1, in which said cyan coupler is N-[ lsion as claimed in claim 1, in which said cyan coupler is N-[2- (Dodecyloxycarbonyl-methoxycarbonyl) -ethyl]- l -l1ydroxy-4 Dodecyloxycarbonyl-methoxycarbonyl) -ethyl l -hydroxy-4 -(2-acetylphenylazo-2-naphthamide of the formula 2-ethoxycarbonylphenylazo)-2-naphthamide of the formula 5 R I (I311 v V -c OHNCHzCHzCOOCHzCOOCnHu -0 OHN(|3H2COOCH2COOC12H24 i CH3 l0 l N=N v N=N C 0 O CZHS (I30 CH1

Claims (4)

1. 2. A light-sensitive silver halide color-photographic emulsion as claimed in claim 1, in which said cyan coupler is N-(1-(Dodecyloxycarbonyl-methoxycarbonyl) -ethyl)-1-hydroxy-2-naphthamide of the formula
2. 3. A light-sensitive silver halide color-photographic emulsion as claimed in claim 1, in which said cyan coupler is N-(2(Dodecyloxycarbonyl-methoxycarbonyl) -ethyl)1-hydroxy-2-naphthamide of the formula
3. 5. A light-sensitive silver halide color-photographic emulsion as claimed in claim 1, in which said cyan coupler is N-(1-(Dodecyloxycarbonyl-methoxycarbonyl) -ethyl)-1-hydroxy-4-(2-acetylphenylazo)-2-naphthamide of the formula
4. 6. A light-sensitive silver halide color-photographic emulsion as claimed in claim 1, in which said cyan coupler is N-(2-(Dodecyloxycarbonyl-methoxycarbonyl) -ethyl)-1-hydroxy-4-(2-ethoxycarbonylphenylazo)-2-naphthamide of the formula