US3645742A

US3645742A - Color photography

Info

Publication number: US3645742A
Application number: US779627A
Authority: US
Inventors: Marcel Hendrik Verbrugghe; Arthur Henri De Cat; Marcel Karel Van Doorselaer
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1968-01-05
Filing date: 1968-11-27
Publication date: 1972-02-29
Anticipated expiration: 1989-02-28
Also published as: DE1816899B2; DE1816899C3; FR1601789A; GB1246114A; DE1816899A1; BE725904A

Abstract

Light-sensitive silver halide emulsions comprising a yellowforming color coupler having the formula WHEREIN: X stands for hydrogen or a group which splits off on color development, D represents a residue rendering the molecule fast to diffusion and comprising from five to 20 carbon atoms, R1 stands for hydrogen, alkyl, alkoxy, halogen, a dialkylamino group or a sulphamoyl group, and Z represents the atoms necessary to close a nucleus of the thiazole series, ARE DESCRIBED. Upon color development of the described emulsions yellow azomethine dyes are formed which have a high stability against heat and moisture and possess favorable spectral properties.

Description

limited @taies Patent Arthur lllenri De Cat, Mortsel; Marcel Karel Van Doorselaer, S-Gravenwezel, all of Belgium [73] Assignee: Gevaert-Agia N.V., Mortsel, Belgium [22] Filed: Nov. 27, 1968 [21] Appl. No.: 779,627

[30] Foreign Application Priority Data Jan. 5, 1968 Great Britain ..854/68 [52] US. Cl ..96/100, 96/563 [51] lnt. Cl .G03c 1/40 [58] Field ofSearch ..96/100, 55, 56.2, 56.3

[56] Reierences Cited UNITED STATES PATENTS 1,915,334 6/1933 Salzberg et a1 ..260/243 2,075,359 3/1937 Salzberg et al ..424/250 2,449,244 9/1948 Mueller et al.... ..96/56.2 X 2,668,112 2/1954 De Cat et al. .96/100 X 2,992,920 7/1961 De Cat et al ..96/56.2 3,245,787 4/1966 Williams et a]. 96/562 X Verhrugglie et al. Feb. 29, 1972 [54] COLOR PHOTOGRAPHY 3,369,899 2/1968 DeCatetal. ..96/100X m1 verbiage wink; 3333,32? 3/1323 viifiifigii Z, 21. 321133? Primary Examiner-William D. Martin Assistant ExaminerM. R. Lusignan Attorney-Alfred W. Breiner 57 ABSTRACT Light-sensitive silver halide emulsions comprising a yellowforming cglg coupler having the formula v s s, s, v s t l X s CO-(EHC ONHC 12 Claims, No Drawings coma rnoroemrav This invention relates to the production of photographic color images, to color couplers for yellow used therein and to photographic materials containing such color couplers.

It is known that for the production of a photographic color image in a light-sensitive silver halide layer, the exposed silver halide is developed to a silver image by means of an aromatic primary amino compound in the presence of a color coupler which reacts with the oxidized developing substance to form a dyestuff on the areas corresponding to the silver image.

In the subtractive three-color photography a light-sensitive photographic color material is used containing a red-sensitized, a green-sensitized and a blue-sensitive silver halide emulsion layer wherein on color development, by use of appropriate color couplers, a cyan, magenta and yellow dyestuff image are formed respectively.

One of the basic difiiculties confronting color photography concerns the stability of the dyes making up the colored photographic images against light, heat and humidity. Although color photography has undergone much improvement since the appearance of the use of coupler compounds for the formation of colored images, greater dye stability is still needed and sought after.

According to the present invention novel photographic coupler compounds of the benzoylacetamide type yielding yellow dyes upon coupling with the oxidized aromatic primary amino developing agent are provided corresponding to the following general formula:

wherein:

X represents a hydrogen atom or a group which splits off on color development, e.g., a halogen 'atom, an S-R group wherein R is alkyl including substituted alkyl, aryl including substituted aryl, etc.

D represents a residue rendering the molecule fast to diffusion e.g., an acyclic aliphatic hydrocarbon residue with from five to 20 carbon atoms,

R 1 stands for hydrogen, alkyl such as methyl, alkoxy such as methoxy, decyloxy, halogen such as chlorine, dialkylamino such as dimethylamino or sulphamoyl such as diethylsulphamoyl, and

Z represents the atoms necessary to close a nucleus of the thiazole series such a thiazole, 4-methyl-thiazole, 4- tert.butyl thiazole, 4-benzyltiazole, 4-phenylthiazole, 5-

phenylthiazole, 4-( p-methoxyphenyU-thiazole, 4-(pchlorophenyl )-thiazole, 4-phenyl-5-fluorosulphonylthiazole, 4-methyl-5-sulphothiazole, 4-(m- Apart from manifesting a high stability against heat and moisture and forming yellow azomethine dye images, which possess, besides favorable spectral properties and a very good stability against light, an exceptionally high degree of resistance under conditions of high humidity and heat exceeding that of the corresponding 2-(p-alkoxybenzoylacetamido)- thiazole color couplers, these yellow color formers also have a high coupling activity, i.e., they furnish dye images with high color density, irrespective of the presence of the displaceable group. This is rather startling since it is generally known amongst others from Veroffentlichungen der wissenschaftlichen Photo-Laboratorien Wolfen Band X (1965) p. 299, S. Hirzel Verlag, Leipzig, Eastern Germany and from US. Pat No. 2,728,658 of Fred C. Mc Crossen, Paul W. Vittum and Arnold Weissberger, issued Dec. 27, 1955 that ortho-substitution, more particularly o-alkoxy substitution in the benzoyl part of benzoylacetarylide color couplers, cuts down the coupling ability of the coupler and decreases the tinctorial power of the dye formed. Thus, it would appear that in the case of 2-benzoylacetamidothiazole color couplers according to the present invention, ortho-substitution does not reduce the coupling ability of the coupler.

The preparation of the yellow-forming color couplers corresponding to the above general formula can be represented by the following reaction scheme CHgClg lCOCHa COOHCOOR -oo-cmcoon NaO CH CHaOH wherein R R R and D have the same significance as above and R represents a lower alkyl group such as methyl and ethyl.

Benzoylacetamide color couplers falling within the ambit of the above general formula I are illustrated as follows HC o-Nncoomco- CHO 1o 33 The following preparation of some specific compounds corresponding to the above general formula illustrate in detail how the yellow color formers can be prepared.

Preparation 1 :Compound 1 a. lll'dodecyloxybenzoyhacetic acid methyl ester.

153 g. (0.5 mole) of tl-dodecyloxy-benzoic acid prepared as described in JACS 64 (1942) 1,961 and 109 ml. of thionyl chloride were refluxed for 3 hours. The excess of thionyl chloride was removed by evaporation and a light brown oily residue was left.

This oily residue was added with stirring to a suspension of 152 g. (1 mole) of the sodium salt of acetyl acetic acid ethyl ester in 250 ml. of diehloromethane. Stirring was continued for 3 hours whereupon the reaction mixture was treated with 500 ml. of diluted hydrochloric acid. The dichloromethane layer was washed with water until it was acid-free, dried over magnesium sulphate and concentrated by evaporation. The oily residue formed was kept for 3 hours in a vacuum of 2-5 mm. Hg at C. in order to remove the acetyl acetic acid ethyl ester.

While stirring the oil was admixed with a solution of 30 g. of sodium methylate in 350 ml. of methanol. After standing for 24 hours the solution was acidified and extracted with dichloromethane. The dichloromethane solution was washed, dried and concentrated by evaporation. A light yellow oil was obtained.

h. Z-amino-4pheny1-thiazole was prepared as described by Dodson and King, .lACS 67 (1945) 2,242. c. 2-(o-dodecyloxybenzoylacetylamino)-4-phenyl-thiazole.

A mixture of 36.2 g. (0.1 mole) of o-dodecyloxybenzoyl acetic acid methyl ester, 17.6 g. (0.1 mole) of 2-amino-4- phenyl thiazole and 0.2 g. of sodium acetate in xylene was heated until the reflux temperature was reached. A mixture of the xylene and the methanol formed was distilled off in a period of 1 hour.

The remaining xylene was distilled off under reduced pressure and to the oily residue 200 ml. hexane was added. The

mixture was allowed to cool with stirring. The precipitate 1 formed was recrystallized from acetonitrile. Melting point: 6869 C.

Preparation 2 Compound 4 a. o-hexadecyloxybenzoyl-acetic acid methyl ester.

This compound was prepared in an analogous way as described in preparation In. starting from 0.5 mole of o-hexadecyloxybenzoic acid which in its turn was prepared according to the method of Stanton et a]. in JACS 64 (1942) 1,961. The o-hexadecyloxybenzoyl-acetic acid methyl ester formed has a melting point of 53-54 C.

b. 2-amino-4-carbethoxy-thiazole was prepared as described in JACS 68 (1946) 268.

c. 2-o(hexadecyloxybenzoylacetylamino)-4-carbethoxythiazole was prepared in an analogous way as describe in preparation 1c. starting from 0.1 mole of o-hexadecyloxybenzoyl acetic acid methyl ester and 0.1 mole of 2-amino-4-carbethoxy-thiazole. A light yellow viscous oil was obtained.

d. 2-(o-hexadecyloxybenzoylacetylamino)-4-carboxythiazole.

0.1 mole of the oil obtained according to preparation 2C., 250 ml. of ethanol and 100 ml. of 2N sodium hydroxide were refluxed for 1 hour. The mixture was acidified with diluted sulphuric acid and the white light-yellow precipitate formed was recrystallized from isopropanol. Melting point: 1 C. Preparation 3 Compound 8 a. 2-(o-hexadecyloxybenzoylacetylamino)-4-(mfluorosulphonylphenyl)thiazole.

This compound was prepared in an analogous way as the compound described in preparation 1 starting from 0.1 mole o-hexadecyloxybenzoyl-acetic acid methyl ester (see preparation and 0.1 of 2-amino-4-(m-fluorosulphonyl-phenyl)- thiazole prepared as described below. A white crystalline product having a melting point of 108 C. was obtained.

b. 2-(o-hexadecyloxybenzoylacetylamino)-4-(m-sulphopheny1)thiazole.

0.1 mole of the above fluorosulphonyl compound in 400 ml. of acetone was heated till the reflux temperature was reached. With stirring, 60 ml. of 51! sodium hydroxide was gently added whereupon the mixture was refluxed for 30 minutes. The mixture was then acidified with an excess of sulphuric acid so that the free sulphonic acid precipitated.

Preparation of 2-amino-4-(m-fluorosulphonyl-phenyl)- thiazole. a. m-fluorosulphonyl-benzoyl chloride.

20.4 g. (0.1 mole) of m-fluorosulphonyl-benzoic acid, prepared by reaction of m-chlorosulphonyl-benzoic acid with potassium fluoride in aqueous dioxane medium, were allowed to react with an excess (0.45 mole) of thionyl chloride, Yield 21.3 g. (96 percent). Boiling point: 1161 17 C./2 mm. Hg. b. m-fluorosulphonyl-acetophenone.

m-fluorosulphonyl-benzoyl chloride was converted to the corresponding acetophenone, essentially according to the procedure developed by Long and Troutman, JACS, 71, 2,473 (1949) for the synthesis of p-nitroacetophenone. The crude product obtained after hydrolysis of diethyl-mfluorosulphonyl benzoyl malonate was washed with a saturated solution of sodium bicarbonate to remove about 5 percent of m-fluorosulphonyl-benzoic acid formed during hydrolysis. From 52.5 g. (0.24 moles) of m-fluorosulphonyl-benzoyl chloride were obtained after recrystallization from about 350 ml. of methanol, 36.8 g. (76 percent) of m-fluorosulphonylacetophenone with melting point 92 C. c. m-fluorosulphonyl-phenacyl bromide.

A solution of 40.4 g. (0.2 mole) of m-fluorosulphonyl acetophenone in 45 ml. of dioxane was brominated at 40-50 C. with 32 g. (0.2 mole) of bromine. The oily bromoketone which separated upon diluting the reaction mixture with water was collected and the aqueous phase was extracted with methylene chloride. The oil and the methylene chloride solution were combined washed with aqueous sodium bicarbonate solution and dried over magnesium sulphate. After removal of the solvent the bromoketone distilled at 170 C./2 mm. Hg. The oily product slowly solidified to a crystalline mass. Melting point 48-50 C. Yield 3.97 g. (78.5 percent).

d. 2-amino-4-(m-fluorosulphonylphenyl)thiazole.

To a suspension of 15.2 g. (0.2 mole) of thiourea in 40 ml. of boiling ethanol was added a solution of 56.2 g. (0.2 mole) of m-fluorosulphonylphenacyl bromide in 45 ml. of dioxane at such a rate that the heat developed by the reaction was sufficient to keep the reaction mixture boiling (4060 min.). The hydrobromide of 2-amino-4-(m-fluorosulphonyl phenyl)- thiazole obtained by cooling the reaction mixture to room temperature was dissolved at 80-90 C. in about 120 cc. of water (containing about 15 percent of ethylene glycol monomethyl ether) and neutralized with sodium bicarbonate. The precipitate was collected, washed with water, and dried at C. Yield 29 g. (62.5 percent). Melting point 154-156 C.

The yellow color formers according to the present invention are of the nondiifusible type, i. e., theyv comprise in their molecule an organic radical sufiiciently large for preventing the color coupler of wandering from the colloid layer in which the coupler is incorporated to another colloid layer.

For preparing a usable photographic multilayer color material the nondiffusing color couplers for each color separation image are usually incorporated into the coating compositions of the differently sensitized silver halide emulsion layers. However, the nondiffusing color couplers may also be added to the coating compositions of non-light-sensitive colloid layers which are in water-permeable relationship with the light-sensitive silver halide emulsion layers, e.g., in layers which are in direct contact with the light-sensitive layers or which are separated from said light-sensitive layers by waterpermeable non-light-sensitive layers.

During the preparation of the light-sensitive color material the nonmigratory yellow-forming color couplers according to the above general formulas can be incorporated in the coating composition of the silver halide emulsion layers or other colloid layers in water-permeable relationship therewith according to any technique known by those skilled in the art for incorporating photographic ingredients, more particularly color couplers, into colloid compositions. For instance, the watersoluble color couplers, i.e., those containing one or more water-solubilizing groups such as sulpho or carboxyl groups (in acid or salt form) can be incorporated into the coating composition of the layer in question from an aqueous solution and the water-insoluble or insufiiciently water-soluble color couplers from a solution in the appropriate water-miscible or water-immiscible high-boiling or low-boiling organic solvents or mixtures thereof whereupon the solution obtained is dispersed, occasionally in the presence of a wetting or dispersing agent, in a hydrophilic colloid composition forming or forming part of the binding agent of the colloid layer. The hydrophilic colloid composition may of course comprise in addition to the colloid carrier all other sorts of ingredients. The water-insoluble color couplers carrying fluorosulphonyl groups or carboxylic acid ester groups such as ethoxycarbonyl groups can also be converted by alkaline hydrolysis in the corresponding sulphonic acids or carboxylic acids respectively which in their turn can be incorporated in hydrophilic colloid compositions in the form of their alkali salts from aqueous solutions.

The solution of said color coupler need not necessarily be dispersed or dissolved directly in the coating composition of the silver halide emulsion layer or other water-permeable layer. Said solution may advantageously be first dispersed or dissolved in an aqueous non-light-sensitive hydrophilic colloid solution whereupon the resultant mixture, after the occasional removal of the organic solvents employed, is intimately mixed with the said coating composition of the light-sensitive silver halide emulsion layer or other water-permeable layer just before coating. For more details about particularly suitable dispersing techniques that can be employed for incorporating the color couplers of the invention into a hydrophilic colloid layer of a photographic material there can be referred to UK. Pat. application 46,459/67 filed Oct. 11, 1967 by Gevaert- Agfa N.V., to UK. Pat. Nos. 791,219 filed Nov. 9, 1955 by Kodak, 1,099,414, 1,099,415, 1,099,416, 1,098,594 1,099,417 all filed Jan. 25, 1965 by Gevaert-Aga N.V., to Belgian Pat No. 705,889 filed Oct. 31, 1967, by Gevaert-Agfa NV. and to U.S. Pat. No. 2,304,940 of Leopold D. Marines and Leopold Godowsky, .1 r. issued Dec. 15, 1942.

The couplers according to the invention may be used in conjunction with various kinds of photographic emulsions. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chloride or mixed silver halides such as silver chlorobromide, silver bromoiodide and silver chlorobromoiodide. The couplers can be used in emulsions of the mixed packet type as described in U.S. Pat. No. 2,698,794 of Leopold Godowsky, issued Jan. 4, 1955, or emulsions of the mixed grain type as described in U.S. Pat. No. 2,592,243 of Burt l-l. Carroll and Wesley T. Manson, Jr., issued Apr. 8, 1952. The color couplers can be used with emulsions wherein latent images are formed predominantly on the surface of the silver halide crystal, or with emulsions wherein latent images are formed predominantly inside the silver halide crystal. I

The hydrophiliccolloid used as the vehicle for the silver halide may be, for example, gelatin, colloidal albumin, zein, casein, a cellulose derivative, a synthetic hydrophilic colloid such as polyvinyl alcohol, poly-N-vinyl pyrrolidone, etc. If

desired, compatible mixtures of two or more of these colloids may be employed for dispersing the silver halide.

The light-sensitive silver halide emulsions of use in the preparation of a photographic material according to the present invention may be chemically as well as optically sensitized. They may be chemically sensitized by effecting the ripening in the presence of small amounts of sulphur-containing compounds such as allyl thiocyanate, allyl thiourea, sodium thiosulphate, etc. The emulsions may also be sensitized by means of reductors, for instance tin compounds as described in French Pat. No. 1,146,955 filed Apr. 1 l, 1956 by Gevaert Photo-Producten N.V. and in Belgian Pat. No. 568,687 filed June 18, 1958 by Gevaert Photo-Producten N.V., iminoamino methane sulphinic acid compounds asdescribed in U.l(. Pat. No. 789,823 filed Apr. 29, 1955 by Gevaert Photo- Producten N.V. and small amounts of noble metal compounds such as gold, plantinum, palladium, iridium, ruthenium and rhodium. They may be optically sensitized by means of cyanine and merocyanine dyes.

The said emulsions may also comprise compounds which sensitize the emulsions by development acceleration, for example compounds of the polyoxyalkylene type such as alkylene oxide condensation products as described among others in U.S. Pat. No. 2,531,832 of William Alexander Stanton, issued Nov. 28, 1950, and 2,533,990 of Ralph Kingsley Blake, issued Dec. 12, 1950, in UK. Pat. Nos. 920,637 filed May 7, 1959, 940,051 filed Nov. 1, 1961, 945,340 filed Oct. 23, 1961, all by Gevaert Photo-Producten N.V. and 991,608 filed June 14, 1961 by Kodak and in Belgian Pat. No. 648,70 filed June 2, 1964 by Gevaert Photo-Production N.V. and onium derivatives of amino-N-oxides as described in UK. Pat. No. 1,121,696 filed Oct. 7, 1965 by Gevaert-Agfa N.V.

Further, the emulsions may comprise stabilizers e.g., heterocyclic nitrogen-containing thioxo compounds such as benzothiazoline-Z-thione and l-phenyl-2-tetrazoline-5-thione and compounds of the hydroxytriazolopyrimidine type. They can also be stabilized with mercury compounds such as the mercury compounds described in Belgian Pat. Nos. 524,121 filed Nov. 7, 1953 by Kodak 677,337 filed Mar. 4, 1966 by Gevaert-Agfa N.V., 707,386 filed Dec. 1, 1967 by Gevaert- Agfa N.V. and in U.S. Pat. No. 3,179,520 of Yoshio Miura, Akasi Kumi and Yosuke Nadajima, issued Apr. 20, 1965.

The light-sensitive emulsions may also comprise all other kinds of ingredients such as plasticizers, hardening agents, wetting agents, etc. Kodak, Kumai.

The nondifi'using yellow color formers described in the present invention are usually incorporated into a blue-sensitive silver halide emulsion. According to a common procedure in the art this silver halide emulsion is coated as the topmost color-couplercontaining layer of a photographic multilayer color material. Such photographic multilayer color material usually consists in the given sequence of a support, a red-sensitized silver halide emulsion layer with a cyan color former, a green-sensitized silver halide emulsion layer with a magenta color former and a blue-sensitive silver halide emulsion layer with a yellow color former. A yellow filter layer generally comprising colloidal silver dispersed in gelatin, is provided usually between the blue-sensitive silver halide emulsion layer containing a yellow color former and the green-sensitized silver halide emulsion layer.

The emulsions can be coated on a wide variety of photographic emulsion supports. Typical supports include cellulose ester film, polyvinylacetal film, polystyrene film, polyethylene terephthalate film and related films or resinous materials, as well as paper and glass.

For the production of photographic color images according to the present invention an exposed silver halide emulsion layer is developed with an aromatic primary amino developing substance in the presence of a color coupler according to the present invention. All color-developing agents capable of forming azomethine dyes can be utilized as developers. Suitable developing agents are aromatic compounds such as pphenylene diamine and derivatives for example N,N-dialkyl-pphenylene diamines such as N,N-diethyl-p-phenylene, diamine, N,N-dialkyl-N'-sulphomethyl-p-phenylene diamines, and N,Ndialkyl-N'-carboxymethyl-p-phenylene diamines.

The following examples illustrate the present invention.

EXAMPLE 1 To a 300 g. of a blue-sensitive silver bromoidide emulsion (2.3 mole percent of iodide) comprising 23 g. of gelatin and an amount of silver halide equivalent to 20 g. of silver nitrate, is added 0.006 mole of color coupler no. 3 of the above list of color couplers. After neutralization and addition of the common additives such as stabilizers, wetting agents, and hardeners the necessary amount of distilled water to obtain 575 g. of emulsion is added whereupon the emulsion is coated on a cellulose triacetate support pro rats of 150 g. per sq.m. The emulsion layer is dried and overcoated with a gelatin antistress layer.

After-drying, the material formed is exposed for 1/20 sec. Through a continuous wedge with constant 0.30 and then developed for 8 min. at 20 C. in a developing bath of the following composition:

N,N-diethyl-p-phenylene diamine 2.75 g.

sulphate hydroxylamine sulphate 1.2 g. sodium hexametaphosphate 4 g. anhydrous sodium sulphite 2 g. anhydrous potassium carbonate 75 g. potassium bromide 2.5 g. water to make I litre The developed material is treated for 2 min. at l820 C. in an intermediate bath comprising 30 g. of sodium sulphate in 1 liter of water.

The material is rinsed for 15 min. with water and treated in a bleach bath of the following composition:

borax 20 g. anhydrous potassium bromide 15 g. anhydrous sodium bisulphate 4.2 g. potassium hexacyanoferrate (I11) g. water to make 1 litre After bleaching, the material is rinsed with water for 5 min. and fixed in an aqueous solution of 200 g. of sodium sodium hydroxide and and 30 cc. of water, are added. After addition of the usual additives thiosulphate per liter.

After a final rinsing for 15 min. the material is dried.

A yellow-colored wedge image is obtained having an absorption maximum of 452 nm.

EXAMPLES 2-4 In three similar silver bromoiodide emulsions as described in Example 1 the color couplers no. 3 is replaced by 0.006 mole of color couplets no. 4, 5 and 7 respectively. After neutralization and addition of the usual ingredients the emulsions are coated, exposed through a continuous wedge and processed as described in example 1.

Yellow-colored wedge images are obtained having absorption maxima of 450 nm. 456 nm. and 456 nm. respectively.

EXAMPLE 5 400 g. of blue-sensitive silver homo-iodide emulsion (5 mole percent of iodide) containing 30 g. of gelatin and an amount of silver halide equivalent to 27.5 of silver nitrate are melted'and diluted with 50 ml. of distilled water. The emulsion is acidified with 72 ccs. of 0.016 N acetic acid whereupon 5 g. of the color coupler no. 2 of the above list of examples of color couplers according to the present invention, dissolved in 25 cc. of ethanol, 5 cc. of 2N sodium hydroxide and 20 cc. of distilled water, are added. Then 5 g. of the color coupler no. 8

of the said list of color couplers, dissolved in 15 cc. of ethanol,

water sodium hexametaphosphate l g. anhydrous sodium sulphite 4 g. N,N-diethyl-p-phenylene diamine hydrochloride 2.7 g. anhydrous sodium carbonate 25 g. potassium bromide 22 g. sodium bicarbonate 0.55 g. water to make 1 litre the developed material is rinsed for l-20 see. whereupon it is treated for 4 min. in a fixing bath of the following composition:

water 800 cc. anhydrous sodium thiosulphate 200 g. sodium bisulphite 12 g. acetic acid (glacial) 12 cc. borax 20 g. potassium alum l g. water to make 1 litre The material is rinsed for 3 min. and then treated for 4 min. in a bleaching bath having the following composition:

water 900 cc. potassium hexacyanoferrate (lll) 75 g. potassium bromide l5 g. acetic acid (glacial) cc. sodium acetate 5 g. potassium alum l5 g. water to make 1 litre After bleaching the material is rinsed with water for 2 min. whereupon it is fixed for another 4 min. in the above fixing bath.

After a final rinsing the material is dried.

A clear transparent yellow-colored wedge image is obtained having an absorption maximum of 439 nm.

The yellow color formers according to the invention form on color development with aromatic primary amines such as p-phenylenediamine yellow dyes which excel by their favorable light absorption in the blue region of the spectrum and little absorption in the other regions. Furthermore, the dyes formed on color development show good resistance to heat, humidity and light and manifest a high activity during development, i.e., they furnish color images having high color density.

in order to prove the favorable characteristics of the 2-(0- alkoxy-benzoylacetamido-)thiazole color couplers according to the present invention as compared with the corresponding 2-(p-alkoxybenzoylacetamide)-thiaxole color couplers comparative test were carried out. For this purpose the sensitometric characteristics were determined after development with p-phenylene diamine sulphate as developing agent of gelatino silver bromo-iodide (2.3 mole percent of iodide) emulsions comprising per kg. 73.4 g. of gelatin, an amount of silver halide equivalent to 47 g. of silver nitrate and a color coupler A having the following formula O io a:

or a color coupler B according to the present invention having the formula incorporated from a solution of 0.01 mole of color coupler in 24 ml. of distilled water, 12 ml. of ethanol and 4.5 ml. of 2N sodium hydroxide.

The sensitometric results are listed in the following table.

Color Relative Gradation Maximum Absorption coupler sensitidensity maximum (mm.)

rity in A I00 [.37 2.50 460 B 162 1.41 2.53 445 From the values of the maximum density it appears that contrary to what could be expected the coupling ability of 2-(- o-alkoxy-benzyl acetamido)-thiazole color couplers is not lower than that of the corresponding p-alkoxy derivatives. Moreover, the sensitivity obtained is markedly higher than that obtained with the corresponding p-alkoxy color couplers.

The resistance to moisture and heat of the dyestuffs formed on development by reaction with the oxidation product of pphenylene-diamine sulphate with the above color couplers is determined from the decrease in density of a developed wedge print after having stored said print for 24 hours at 60 C. and percent of relative humidity while being protected from light.

The results attained are listed in the following table.

Color Percentage decrease in density at the Coupler following density values D=0.5 D=l .0 D: 1 v5 D=2.0

A 66% 74% 75% 77% B l2% -IO% 9% ll% We claim:

1. A light-sensitive silver halide emulsion containing a yellow-forming color coupler corresponding to the general formula:

D represents a residue rendering the molecule fast to diffusion and comprising from five to 20 carbon atoms, R, stands for hydrogen, alkyl, alkoxy, halogen, a dialkylamino group or a sulphamoyl group, and Z represents the atoms necessary to close a nucleus of the thiazole series.

2. A light-sensitive silver halide emulsion according to claim 1 in which Z group represents the atoms necessary to close a thiazole nucleus or thiazole nucleus with a fused aliphatic, aromatic or heterocyclic ring system.

3. A light-sensitive silver halide emulsion according to claim 1, in which the Z group represents a thiazole nucleus submnl i m-g group wherein R is aryl.

5. The light-sensitive emulsion of claim 1 wherein R is lower alkyl or lower alkoxy.

6. The light-sensitive emulsion of claim 1 wherein the color coupler has the formula 7. Process for the production of a photographic color image which comprises imagewise exposing of a photographic element containing in a blue-sensitive silver halide emulsion layer or an adjacent water-permeable layer a color coupler corresponding to the following general formula:

wherein:

X is hydrogen or a group which splits off on color development,

D is a residue rendering the molecule fast to diffusion and comprising from five to carbon atoms,

- R, is hydrogen, alkyl, alkoxy, halogen, a dialkylamino group or a sulphamoyl group, and

Z represents the atoms necessary to close a nucleus of the thiazolc series,

and developing the imagewise exposed element with an aromatic primary amino color-developing agent.

8. The process according to claim 7 in which the Z group represents the atoms necessary to close a thiazole nucleus or thiazole nucleus with a fused aliphatic, aromatic or heterocyclic ring system.

9. The process according to claim 7, in which the Z group represents a thiazole nucleus substituted by an alkyl group, an aryl group, an aralkyl group, a heterocycle, a dialkylamino group, a sulphamoyl group, an alkoxycarbonyl group, a fluorosulphonyl group or a sulpho or carboxyl group in acid or salt form.

10. The process of claim 7 wherein X is a halogen atom or a group wherein R is aryl.

11. The process of claim 7 wherein R, is lower alkyl or lower alkoxy.

12. The process of claim 7 wherein the color coupler has the formula

Claims

2. A light-sensitive silver halide emulsion according to claim 1 in which Z group represents the atoms necessary to close a thiazole nucleus or thiazole nucleus with a fused aliphatic, aromatic or heterocyclic ring system.
3. A light-sensitive silver halide emulsion according to claim 1, in which the Z group represents a thiazole nucleus substituted by an alkyl group, an aryl group, an aralkyl group, a heterocycle, a dialkylamino group, a sulphamoyl group, an alkoxycarbonyl group, a fluorosulphonyl group or a sulpho or carboxyl group in acid or salt form.
4. The light-sensitive silver halide emulsion of claim 1 wherein X is a halogen atom or a group wherein R is aryl.
5. The light-sensitive emulsion of claim 1 wherein R1 is lower alkyl or lower alkoxy.
6. The light-sensitive emulsion of claim 1 wherein the color coupler has the formula
7. Process for the production of a photographic color image which comprises imagewise exposing of a photographic element containing in a blue-sensitive silver halide emulsion layer or an adjacent water-permeable layer a color coupler corresponding to the following general formula: wherein: X is hydrogen or a group which splits off on color development, D is a residue rendering the molecule fast to diffusion and comprising from five to 20 carbon atoms, R1 is hydrogen, alkyl, alkoxy, halogen, a dialkylamino group or a sulphamoyl group, and Z represents the atoms necessary to close a nucleus of the thiazole series, and developing the imagewise exposed element with an aromatic primary amino color-developing agent.
8. The process according to claim 7 in which the Z group represents the atoms necessary to close a thiazole nucleus or thiazole nucleus with a fused aliphatic, aromatic or heterocyclic ring system.
9. The process according to claim 7, in which the Z group represents a thiazole nucleus substituted by an alkyl group, an aryl group, an aralkyl group, a heterocycle, a dialkylamino group, a sulphamoyl group, an alkoxycarbonyl group, a fluorosulphonyl group or a sulpho or carboxyl group in acid or salt form.
10. The process of claim 7 wherein X is a halogen atom or a group wherein R is aryl.
11. The process of claim 7 wherein R1 is lower alkyl or lower alkoxy.
12. The process of claim 7 wherein the color coupler has the formula