EP0113484A1

EP0113484A1 - Novel 2-equivalant cyan-forming couplers and photographic elements containing them

Info

Publication number: EP0113484A1
Application number: EP83200020A
Authority: EP
Inventors: Marcel Jacob Monbaliu; Paul Louis Van Meerbeeck; Raphael Karel Van Poucke
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1983-01-10
Filing date: 1983-01-10
Publication date: 1984-07-18

Abstract

2-equivalent cyan-forming phenol- or naphthol type couplers capable of forming a cyan indoaniline dye in a photographic element by reaction with an oxidized aromatic primary developing agent, said couplers containing an a,a-fluorinated alkoxy substituent as coupling off group.

These cyan-forming couplers can be incorporated e.g. in a red-sensitized silver halide emulsion layer of a photographic multilayer colour element or in a non-light-sensitive colloid layer in water-permeable relationship with such a layer.

Description

The present invention relates to novel 2-equivalent cyan-forming couplers, to the use thereof in the production of photographic colour images, and to photographic elements containing such couplers.
It is known that for the production of a photographic colour image in a light-sensitive silver halide emulsion layer, the exposed silver halide is developed to a silver image by means of an aromatic primary amino compound in the presence of a coupler, which reacts with the oxidized developing substance to form a dye at the areas corresponding to the silver image.
In subtractive three-colour photography use is made of a light-sensitive photographic colour element comprising a support, red-sensitized, green-sensitized, and blue-sensitive silver halide emulsion layers, wherein upon colour development using appropriate couplers, cyan, magenta, and yellow dye images are formed in said layers, respectively. The red-sensitized silver halide emulsion layers usually contains cyan-forming couplers of the phenol or naphthol type.
The reaction between the coupler and the oxidized colour developing substance proceeds at the active site of the coupler. Couplers having a hydrogen atom at the active site are 4-equivalent couplers, which need 4 mol of exposed silver halide to form but 1 mol of dye. Couplers, however, which at their active site have a group that can be eliminated, are called 2-equivalent couplers. The eliminable group is generally known as coupling off group. The latter couplers require only 2 mol of exposed silver halide to form 1 mol of dye. This offers the great advantage that the amount of silver halide in the light-sensitive layer can be reduced, which may result in thinner light-sensitive layers and films. As a consequence of this reduction in thickness the processing time of these layers and films is shortened.
A large variety of coupling off groups are known already, among which the substituted alkoxy groups constitute an interesting class. In particular the published Japanese Patent Application 50-120334 describes couplers having B,₁3-fluorinated ethoxy coupling off groups. 2-Equivalent couplers h-ve important advantages as described above, though many of the known 2-equivalent cyan-forming couplers have-serious-disadvantages such as their high cost of synthesis, an unsatisfactory photographic reactivity, an insufficient dispersibility, and/or a poor stability.
The complex and/or lengthy reaction sequence leading to many known couplers has, of course, a bearing on their cost and consequently on the total cost of the light-sensitive element containing them.
An often encountered difficulty with water-insoluble 2-equivalent couplers is that they react very slowly with the oxidized colour developing agent.
A frequently occurring problem caused by water-insoluble couplers is that the shelf-life of dispersions of such couplers may be rather restricted. Dispersions of water-insoluble couplers, after having been prepared in bulk for economic reasons, need to be stored for a given time and are used later on batch-wise in the production of colour elements. However, most of the customarily used dispersions of couplers, are prepared with the aid of a wetting agent and an oil-former in an aqueous colloid medium e.g. a gelatin solution and thus need to be stored in cooling chambers, which results in chilling. As a consequence, the chilled dispersions have to be remelted before addition to the silver halide emulsion. This cold storage and the remelting require much energy-spending and technical background. Other techniques e.g. those described in the British Patent Specification 1,297,947 allow to make dispersions of water-insoluble couplers in water, these dispersions being stored at room temperature. However, few couplers can be dispersed successfully according to this interesting technique.
Another problem is that certain couplers, however interesting other characteristics they may have, are insufficiently stable.
It is therefore an object of the present invention to provide novel 2-equivalent cyan-forming couplers, which have improved properties and at the same time are very interesting from an economical standpoint.
Another object is to provide photographic elements containing said novel 2-equivalent cyan-forming couplers.
A further object is to provide photographic multilayer colour elements containing said novel 2-equivalent cyan-forming couplers.
Another object-of the invention is to produce a photographic colour image by development of a photographic multilayer colour element containing said novel 2-equivalent cyan-forming couplers.
Other objects of the invention will become apparent from the disclosure hereinafter.
The above objects are accomplished with the aid of novel 2-equivalent fluorine-containing cyan-forming couplers, which can be synthesized in a very economic way with high yields, have a high photographic reactivity as well as a high stability, and can be dispersed successfully in water.
According to the present invention there are provided novel phenol- or naphthol-type couplers capable of forming a cyan indoaniline dye by reaction with an oxidized aromatic primary amino developing agent, said couplers containing an α,α -fluorinated alkoxy coupling off group.
More particularly, in accordance with the present invention there are provided novel 2-equivalent cyan-forming couplers corresponding to one of the following general formulae I and II :
wherein :

Y is -CO- or -SO₂-,
R represents an alkyl group, an aryl group, or a heterocyclic 5- or 6- membered group, which groups may be substituted,
R 2 represents a -CF₂R group, R being hydrogen, -CFHCF₃, or -CFHC1,
R³ is a ballasting group of sufficient size rendering said coupler non-diffusing in an alkali-permeable layer of a photographic element.

The present invention also provides a photographic element, and in particular a photographic multilayer colour element comprising at least three silver halide emulsion layers, which have been differently optically sensitized and wherein a novel coupler as set forth above is present in the red-sensitized silver halide emulsion layer or in a non-light-sensitive colloid layer in water-permeable relationship therewith.
Examples of R¹ and R³ in the above general formulae will be described detailedly hereinafter.
In the general formula I the symbol R can represent a straight chain or branched chain alkyl group or a cyclic alkyl group, preferably an alkyl group having from 1 to 18 carbon atoms (e.g. methyl, ethyl, n-propyl, isopropyl, butyl, tert-butyl, pentyl, tert-pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, pentadecyl, heptadecyl, octadecyl, cyclohexyl), an aryl group (e.g. phenyl, naphthyl), or a 5- or 6- membered heterocyclic group (e.g. thiazolyl, furyl, thienyl, pyrrolyl, imidazolyl, pyrazolinyl, pyrazolyl, pyridyl, pyridinyl, quinolyl, pyrimidinyl, oxazolyl, oxathienyl, thiazolinyl, triazinyl, pyranyl, pyrazolidinyl, pyrazinyl, isothiazolyl, isoxazolyl, imidazolinyl, imidazolidinyl, pyrrolinyl, piperidyl, piperazinyl, morpholinyl). These groups may be substituted with one or more substituents selected from an alkyl group (e.g. methyl, ethyl, propyl, butyl, pentyl, etc.), a halogen atom (e.g. chloro, fluoro, etc.), a nitro group, a cyano'group, an aryl group (e.g. phenyl, naphthyl, etc.), an alkoxy group (e.g. methoxy, ethoxy, methoxyethoxy, 2-ethylhexyloxy, etc.), an aryloxy group (e.g. phenoxy, 4-hydroxyphenoxy, 2,4-di-tert-pentyl- phenoxy, naphthoxy, etc.), a carboxy group, an alkylcarbonyl group (e.g. acetyl, tetradecanoyl, etc.) an arylcarbonyl group (e.g. benzoyl, etc.), an alkoxycarbonyl group (e.g. methoxycarbonyl, benzyloxycarbonyl, etc.), an aryloxycarbonyl group (e.g. phenoxycarbonyl, p-tolyloxycarbonyl, etc.), an acyloxy group (e.g. acetyl- oxy, benzoyloxy, etc.), a sulphamoyl group (e.g. N-ethylsulphamoyl, 5-N-octadecyl-sulphamoyl, etc.), a carbamoyl group (e.g. N-ethylcarbamoyl, N-methyl-N-dodecylcarbamoyl, etc.), an acylamido group (e.g. acetamido, benzamido, etc.), a diacylamido group (e.g. succinimido, hydantoinyl, etc.) a ureido group (e.g. methylureido, phenylureido, etc.), an alkylsulphonamido group (e.g. methylsul- phonamido, dodecylsulphonamido, methoxyethylsulphonamido, etc.) and a hydroxy group. When_the alkyl group is substituted with fluorine atoms, it may be a so-called polyfluoroalkyl group. Preferred examples of R substituents are methyl, perfluoropropyl, and 2,4-di(2-chloro-1,1,2-trifluoro-ethoxy)phenyl.
In both the general formulae I and II the ballasting group R³ can represent an aliphatic hydrocarbon group, which may be saturated or unsaturated and may have an unbranched chain, a branched chain, or a cyclic structure, preferably an alkyl group (e.g. hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, 2,7,8-trimethyldecyl, 4-ethyl-5-methyloctyl, 2,3,5-trimethyl-4-propylheptyl, 4-isobutyl-2,5-dimethylheptyl, cyclohexyl etc.), an alkenyl group (e.g. vinyl, allyl, isopropenyl, propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-hexenyl, 1,4-hexadienyl, 3,4-dipropyl-1,3-hexadien-5-ynyl, 5-ethynyl-1,3,6-heptatrienyl, 4-vinyl-l-hepten-5-ynyl, 1,3-cyclohexadienyl etc.), an aryl group (e.g. phenyl, naphthyl etc.), an alkoxy group (e.g. methoxy, ethoxy, n-propoxy, isopropoxy, butoxy, pentoxy, hexyloxy, heptyloxy, octyloxy etc.), or an aryloxy group (e.g. phenoxy, naphthoxy etc.). These groups may be substituted with one or more substituents selected from an alkyl group, a halogen atom, an aryl group, an alkoxy group, an aryloxy group, examples of which substituents are given in the significance of R hereinbefore, and an alkylthio group or an arylthio group. Preferred examples of a substituted ballasting group R³are 1-(3-pentadecylphenoxy)propyl, 1-[2,4-(di-tert-pentyl-)phenoxy]- propyl, 1-(4-dodecyloxyphenoxy)propyl, 3-[2,4-(di-tert-pentyl)-phenoxy]-propyl, 4-[2,4-(di-tert-pentyl)phenoxy]-butyl, 1,3-(dioctyloxy)-isopropoxy-2-chloro-5-hexadecyloxycarbonyl-phenyl, 5-(p-hexadecyloxyphenyl)-1,3-thiazole-2-yl.
Novel cyan-forming 2,5-diacylamino-phenol couplers that correspond to the general formula I wherein Y represents -CO- and that carry at the 4-position a 1,1,2,3,3,3-hexafluoropropoxy substituent or a 2-chloro-1,1,2-trifluoroethoxy substituent as coupling off group can be prepared according to the following reaction scheme, wherein R and R³ have the significance as defined above :
A detailed description of the preparation of novel cyan-forming 2,5-diacylamino-phenol couplers that correspond to the general formula I wherein Y represents -CO- and that carry at the 4-position a 1,1,2,3,3,3-hexafluoropropoxy substituent as coupling off group, is given now. 1.1. 1,4-dibenzyloxy-2-perfluorobutyroylaminobenzene
A volume of 163 ml (1.87 mol) of oxalyl chloride was added dropwise in 1 h to a cooled (-15 °C) mixture of 750 ml of dimethylformamide and 750 ml of acetonitrile in such a way that the temperature did not surpass -5°C. In 15 min 215 ml (1.65 mol) of perfluorobutyric acid was added at approximately 0 °C to the resulting white suspension. The mixture was stirred for 30 min. A solution of 458 g (1.5 mol) of 2,5-dibenzyloxyaniline in a mixture of 750 ml of dimethylformamide and 312 ml of pyridine was added in 90 min at a temperature between 5 and 10°C. Next, the supsension was stirred at room temperature for 1 h. The resulting brown solution was poured out in a mixture of 8 1 of water and 200 ml of 5 N hydrochloric acid. The precipitate was filtered off, stirred in 10 1 of water, filtered again, and rinsed with 3 1 of methanol. Yield : 660 g (87%) of 1,4-dibenzyloxy-2-perfluorobutyroylaminoben- zene melting at 91°C. 1.2. 1,4-dibenzyloxy-5-nitro-2-perfluorobutyroylaminobenzene
A mixture of 128 ml of concentrated nitric acid and 50 ml of concentrated sulphuric acid was added in 15 min to a suspension of 652 g (1.3 mol) of intermediate product (1.1) in 10 1 of acetic acid. The temperature rose from 20 to 50°C. A brown solution was formed for a time, in which a product started precipitating after a short while. The reaction mixture was stirred for 10 min and then diluted with 10 1 of water. The precipitate was filtered off, rinsed with water, and dried. Yield : 679 g (95%) of 1,4-dibenzyloxy-5 nitro-2-perfluorobutyroyl- aminobenzene melting at 115°C. 1.3. 2-nitro-4 benzyloxy-5-perfluorobutyroylaminophenol
418 g (3.1 mol) of anhydrous aluminium chloride was added portionwise in 30 min to a suspension of 677 g (1.24 mol) of the intermediate product (1.2) in 3500 ml of acetonitrile. A red solution was obtained, the temperature of which rose to 60°C. The mixture was stirred for 30 min. A volume of 25 ml of pyridine was added and the temperature of the reaction mixture was kept at 60-65°C for 1 h. 3 kg of ice was added to the resulting reaction mixture. The yellow precipitate was filtered off and rinsed with water until free from acid. The wet precipitate was recrystallized from 4.5 1 of ethylene glycol monomethyl ether.
Yield : 433 g (76%) of 2-nitro-4-benzyloxy-5-perfluorobutyroyl- aminophenol melting at 140°C.

1.₄. 2-(1,1,2,3,3,3-hexafluoropropoxy)-4-perfluorobutyroylamino-5-benzyloxy-nitrobenzene.

228 g (0.5 mol) of intermediate product (1.3) was dissolved in 1000 ml of dimethylformamide and 82.8 ml (0.6 mol) of triethylamine. A volume of 14 1 of hexafluoropropene was introduced into the solution in 1 h whilst cooling with carbon dioxide and isopropanol. The temperature gradually rose to 35°C and then started falling after 30 min. The brown solution was acidified with 200 ml of 5 N hydrochloric acid and diluted with 5 1 of water. The resulting precipitate was filtered and rinsed with water. The red precipitate was recrystallized from 1.2 1 of ethanol.
Yield : 270 g (89%) of 2-(1,1,2,3,3,3-hexafluoropropoxy)-4-per- fluorobutyroylamino-5-benzyloxy-nitrobenzene melting at 75°C.

1.5. 2-(1,1,2,3,3,3-hexafluoropropoxy)-4-perfluorobutyroylamino-5-hydroxy-aniline.

A solution of 79 g (0.13 mol) of the intermediate product (1.4) in 500 ml of ethylene glycol monomethyl ether was shaken with 0.52 g of Pd-C (5%) at 120°C in an autoclave with an initial pressure of 100 bar. After 4 h of shaking 0.52 mol of hydrogen had been taken up for the reduction of the nitro group and for the debenzylation. The catalyst was filtered off and the filtrate was diluted with 2 1 of water. The white precipitate was filtered and dried.
Yield : 61.5 g (97%) of 2-(1,1,2,3,3,3-hexafluoropropoxy)-4-per- fluorobutyroylamino-5-hydroxy-aniline melting at 144°C.
1.6. Couplers corresponding to general formula I ( Y representing

-_CO- and R² representing -CF CHFCF ₃

0.1 mol of the aniline (intermediate product 1.5) was dissolved in 200 ml of acetonitrile or in a mixture of equal volumes of acetonitrile and dimethylformamide. An amount of 12.6 g of sodium hydrogen carbonate and 0.1 mol of the acid chloride R³COC1 was added. After 30 min of stirring at 50°C 2 ml of pyridine was added to the resulting mixture. The temperature of the mixture was kept at 50°C for 30 to 60 min. The reaction mixture was acidified with 5 N hydrochloric acid and diluted with 2 1 of water. The product obtained was recrystallized from an appropriate solvent or purified by column chromatography.
The preparation of novel cyan-forming 2,5-diacylamino-phenol couplers that corresponds to the general formula I wherein Y represents -CO-, but that carry at the 4-position a 2-chloro-1,1,2-trifluoroethoxy substituent in stead of a 1,1,2,3,3,3-hexafluoropropoxy substituent as coupling off group, can be performed as described in 1.1 to 1.3 above, followed by e.g. adding 136.8 g (0.3 mol) of intermediate product (1.3) portion-wise to a suspension of 15.84 g (0.33 mol) of 50% sodium hydride in oil in 500 ml of dry dimethylformamide; adjusting the temperature of the red solution to 80°C; introducing trifluorochloroethylene slowly for 2 h; acidifying the solution with 50 ml of 5 N hydrochloric acid and diluting with 1.5 1 of water; stirring the resulting oil for a few hours so that it granulated; filtering off the resulting precipitate and recrystallizing from 400 ml of a mixture of methanol/water (1:8), thus yielding 125 g (73%) of 2-(2-chloro-1,1,2-trifluoroethoxy)-4- perfluorobutyroylamino-5-benzyloxy-nitrobenzene melting at 92°C, which is analogous to intermediate product (1.4), and finally following the procedure described in steps 1.5 and 1.6 hereinbefore.
The novel cyan-forming 2-sulphonamido-5-acylamino-phenol couplers that correspond to the general formula I wherein Y represents -S0₂-and that carry at the 4-position a 1,1,2,3,3,3-hexafluoropropoxy substituent or a 2-chloro-1,1,2-trifluoroethoxy substituent as coupling off group can be prepared as described hereinafter in detail: 2.1. 2,5-dibenzyloxy-methylsulphonylaminobenzene.
61 g (0.2 mol) of 2,5-dibenzyloxy-aniline was dissolved in 250 ml of acetonitrile and 18 ml of pyridine. A volume of 16.8 ml (0.21 mol) of methanesulphochloride was added thereto. The reaction mixture was refluxed for 2 h. The solution was poured out in 1 1 of 0.1 N hydrochloric acid and the resulting precipitate was dried and stirred in 250 ml of methanol.
Yield : 70 g (90%) of 2,5-dibenzyloxy-methylsulphonylaminobenzene melting at 136°C.

2.2. 2,5-aibenzyloxy-4-methylsulphonylamino-nitrobenzene

A mixture of 13 ml of concentrated nitric acid and 7.5 ml of concentrated sulphuric acid was added in 5 min to a suspension of 62.5 g (0.16 mol) of intermediate product (2.1) in 500 ml of acetic acid. The reaction mixture was kept at 50°C for 90 min. The suspension obtained was poured out in two liters of water and the precipitate was recrystallized from ethylene glycol monomethyl ether.
Yield : 55 g (80%) of 2,5-dibenzyloxy-4-methylsulphonylamino- nitrobenzene melting at 153°C.

2.3. 2-nitro-4-benzyloxy-5-methylsulphonylamino-phenol.

166 g (1.25 mol) of anhydrous aluminium chloride was added portionwise to a suspension of 214 g (0.5) mol) of intermediate product (2.2). The temperature rose to 70°C. The reaction temperature was kept at 70°C for 1 h. The reaction mixture was decanted carefully in 5 1 of 1 N hydrochloric acid. The yellow precipitate was rinsed with water until free from acid and recrystallized from ethylene glycol monomethyl ether.
Yield : 268 g (63%) of yellow 2-nitro-4-benzyloxy-5-methylsul- phonylamino-phenol melting at 192°C.

2.4. 2-(1,1,2,3,3,3-hexafluoropropoxy)-4-methyisulphonylamino-5-benzyloxy-nitrobenzene.

101.5 g (0.3 mol) of intermediate product (2.3.) was dissolved in 500 ml of dimethylformamide and 63 m1 (0.5 mol) of triethylamine. Hexafluoropropene was introduced for 1 h whilst cooling with carbon dioxide and isopropanol. The temperature rose to 40°C and started falling after 1 h to 30°C. The reaction mixture was poured out in 3 1 of water and 100 ml of 10 N hydrochloric acid. The precipitation was recrystallized from ethanol.
Yield : 120 g (82%) of 2-(1,1,2,3,3,3-hexafluoropropoxy)-4-me- thylsulphonylamino-5-benzyloxy-nitrobenzene melting at 152°C.

2.5. 2-metnylsulphonylamino-4-(1,1,2,3,3,3-hexafluoropropoxy)-5-aminophenol.

A solution of 120 g (0.24 mol) of intermediate product (2.4.) in 550 m1 of ethylene glycol monomethyl ether was shaken in an autoclave with 5 ml of Raney nickel suspension at 120°C and an initial pressure of 100 bar. After 4 h of agitation no hydrogen was taken up any longer. The catalyst was filtered off and the filtrate was diluted with 100 ml of a 1% aqueous sodium dithionite solution. The mixture was concentrated by evaporation to a volume of 1/3 and then poured out in 3 1 of water.
Yield : 70.5 g (80%) of 2-methylsu1phonylamino-4-(1,1,2,3,3,3-hexafluoropropoxy)-5-aminophenol melting at 166°C.

Coupler 12

A solution of 31.7 g (0.09 mol) intermediate product (2.5.), 37.2 g (0.091 mol) of -(3-pentadecylphenoxy)butyryl chloride in 10 ml of pyridine and 250 ml of acetonitrile was refluxed for 2 h. the reaction mixture was poured out in 2 1 of water and the resulting precipitate was recrystallized from methanol.

Yield : 47 g (70%) of coupler 12 melting at 91°C.

Phenol couplers comprising instead of the 1,1,2,3,3,3-hexafluoropropoxy coupling off group a 2-chloro-1,1,2-trifluoroethoxy coupling off group can be prepared analogously to the 2,5-diacylamino-phenol couplers comprising such a 2-chloro-1,1,2-trifluoroethoxy group, as described hereinbefore.
Hydrolysis of certain couplers corresponding to the general formula I may lead to the formation of corresponding aminophenols, which may themselves serve as starting products in the preparation of other interesting couplers according to general formula I. For illustrative purposes, the hydrolysis of coupler 6 is described hereinafter.
55.2 g (0.070 mol) of coupler 6 was dissolved in 500 ml of acetonitrile and 15 ml of hydrazine hydrate. The resulting mixture was stirred for 2 h, left standing for 2 days, and then diluted with 1 1 of water. The precipitate was filtered off, dried, and recrystallized from ethanol.
Yield : 37 g (80%) of 2-amino-4-(1,1,2,3,3,3-hexafluoropropoxy) -5-[2-(m-pentadecylphenoxy)-butyramido]-phenol melting at 83°C. From this aminophenol i.a. coupler 15 can be prepared according to known methods.
The novel cyan-forming 2-N-substituted carbamoyl-4-,x,a-fluorinated alkoxy-naphthols corresponding to the general formula II can be prepared according to the following reaction scheme, wherein R³ has the significance as defined above :
A detailed description of the preparation of novel cyan-forming 2-N-substituted carbamoyl-4-α,αfluorinated alkoxy-naphthol couplers corresponding to the general formula II is given hereinafter. 3.1. 4-(1,1,2,3,3,3-hexafluoropropoxy)-1-hydroxy-2-naphthoic acid
102 g (0.50 mol) of 1,4-dihydroxy-naphthoic acid was dissolved in 500 ml of anhydrous dimethylformamide. An amount of 104 g (0.75 mol) of potassium carbonate was added thereto. In 90 min 22 1 of hexafluoropropene was introduced into the reaction mixture. Initially the temperature rose to 45°C and started falling after 1 h. Evolution of gas was avoided by cooling with carbon dioxide in isopropanol. The reaction mixture was acidified with 100 ml of acetic acid and diluted with 2 1 of water. The precipitate obtained was filtered off, dried, and recrystallized from 1000 ml of dichloroethane.
Yield : 85 g (55%) of 4-(1,1,2,3,3,3-hexafluoropropoxy)-I-hydroxy-2-naphthoic acid melting at 222°C.

3.2. 4-(1,1,2,3,3,3-hexafluoropropoxy}-1-hydroxy-2-naphthoic acid

phenyl ester

39 g (0.105 mol) of intermediate product (3.1.) and 11.3 g (0.12 mol) of phenol were dissolved in a mixture of 300 ml of acetonitrile and 10 ml of dimethylformamide. A volume of 13 ml (0.14 mol) of phosphoryl chloride was added thereto and the reaction mixture was refluxed for 3 h. The mixture was diluted with 1 1 of water and then neutralized with sodium hydroxide to pH 5. The precipitate was filtered off, dried, and recrystallized from 100 ml of ethanol.
Yield : 32 g (70%) of 4-(1,1,2,3,3,3-hexafluoropropoxy)-1-hydroxy -2-naphthoic acid phenyl ester.

3.3. 4-(1,1,2,3,3,3-hexafiuoropropoxy)-2-N-di-tert-pentylphenoxybutyl- carbamoyl-naphthol (coupler 18)

A mixture of 31 g (0.072 mol) of intermediate product (3.2.) and 24.4 g (0.08 mol) of 2,4-di-tert-pentylphenoxybutylamine was heated to 125°C at a reduced pressure of 20 mm Hg. The condensation had come to an end after 3 h. The reaction product was then purified by column chromatography.
Yield : 35 g (76%) of 4-(1,1,2,3,3,3-hexafluoropropoxy)-2-N-di-tert-pentylphenoxybutylcarbamoyl-naphthol melting at 93°C.
Naphthol couplers according to the invention comprising instead of the 1,1,2,3,3,3-hexaftuoropropoxy coupling off group a 2-chioro-1,1,2-trifluoroethoxy coupling off group can be prepared as follows :

4.1. 4-(2-chloro-1,1,2-trifluoroethoxy)-1-hydroxy-2-naphthoic acid

414 g (3 mol) of dry potassium carbonate and 5 g of sodium dithionite were stirred in 1.5 1 of N-methyl-pyrrolidone. An amount of 306 g (1.50 mol) of 1,4-dihydroxy-naphthoic acid was added thereto batch-wise in 30 min. The temperature rose to 40°C. The mixture was the heated to 100°C and trifluorochloroethylene was introduced. The temperature rose to 110-115°C. Gas was introduced for 6 h at this temperature. The reaction mixture was poured out with stirring in 10 1 of 1 N hydrochloric acid (frothing). The oil obtained gradually granulated upon stirring. The precipitate was filtered off and dried.
457 g of product was obtained. After recrystallization from 1.8 1 of toluene 330 g (69%) of 4-(2-chloro-1,i,2-trifluoroethoxy)-1-hydroxy-2-naphthoic acid melting at 225°C (decomposition) was obtained. 4.2. 4-(2-chloro-1,1,2-trifluoroethoxy)-2-N-hexadecylcarbamoylnaphthol (coupler 19)
15.4 g (0.075 mol) of dicyclohexyl carbodiimide was added to a suspension of 22.4 g (0.07 mol) of 4-(2-chloro-1,1,2-trifluoroethoxy) -1-hydroxy-2-naphthoic acid in 150 ml of dry ethyl acetate. The mixture was refluxed for 4 hours and then cooled to room temperature. The N₁, N₂-dicyclohexyl urea was filtered off and the resulting filtrate was concentrated by evaporation. The residual oil was recrystallized from 200 ml of hexane.
Yield : 23.2 g (78%) of 4-(2-chloro-1,1,2-trifluoroethoxy)-2-N-hexadecylcarbamoylnaphthol melting at 74°C.
Another naphthol coupler comprising a 2-chloro-1,1,2-trifluoroethoxy coupling off group was prepared as follows :

5.1. 4-(2-chloro-1,i,2-trifluoroethoxy)-1-hydroxy-2-naphthoic acid (see preparation described under 4.1 hereinbefore)
5.2. 4-(2-chloro-1,1,2-trifluoroethoxy)-1-hydroxy-2-naphthoic acid phenyl ester

This product was synthesized in an analogous was as described under 3.2 hereinbefore but starting from 32 g of intermediate product (5.1.), 13,2 g of phenol, and 14 ml of phosphoryl chloride in a mixture of 300 ml of acetonitrile and 10 ml of dry dimethylformamide.
Yield : 15 g of 4-(2-chloro-1,1,2-trifluoroethoxy)-1-hydroxy-2-naphthoic acid phenyl ester melting at 103°C.

5.3. 4-(2-chlora-1,1,2-trifluoroethoxy)-1-hydroxy-2-N-(2-chloro-5-n-hexadecyloxycarbonyl-phenyl)-carbamoyl-naphthol (coupler 20)

This product was synthesized in an analogous way as described under (3.3.), but starting from 11.5 g (0.029 mol) of intermediate product (5.2.) and 11.5 g (0.029 mol) of 3-amino-4-chlorobenzoic acid-n-hexadecyl ester. The crude product was purified by recrystallization from ethanol. Yield : 14.2 g (70%) of 4-(2-chloro-1,1,2-trifluoroethoxy)-1-hydroxy-2-N-(-chloro-5-n-hexadecyloxycarbonyl- phenyl)-carbamoyl-naphthol melting at 85°C.
Naphthol couplers according to the invention comprising instead of a 1,1,2,3,3,3-hexafluoropropoxy or 2-chloro-1,1,2-trifluoroethoxy coupling off group a difluoromethoxy coupling off group can be prepared as follows :

6.1. 4-difluoromethoxy-l-hydroxy-2-naphthoic acid

112.3 g (0.55 mol) of 1,4-dihydroxy-2-naphthoic acid was dissolved in a mixture of 300 ml of dioxan and a solution of 100 g of sodium hydroxide and 2 g of sodium dithionite in 300 ml of water. The temperature was adjusted to 80°C. Next, chlorodifluoromethane was introduced. After 4 h another 100 g of sodium hydroxide was added and gas was introduced for 6 h. The dark solution obtained was diluted with 1 1 of water and acidified with 200 ml of 5 N hydrochloric acid. The brown precipitate was filtered off and purified by chromatography.
Yield : 53 g of 4-difluoromethoxy-l-hydroxy-2-naphthoic acid melting at 200-205°C (decomposition).

6.2. 4-difluoromethoxy-2-N-di-tert-pentylphenoxybutyl-carbamoyl-

naphthol (coupler 22)

This product was synthesized in an analogous way as described under (4.2.), but starting from 12.7 g (0.05 mol) of intermediate product (6.1.), 15.9 g (0.051 mol) of 2,4-di-tert-pentyl-aminobutyl- oxybenzene, 11 g (0.052 mol) of dicyclohexyl carbodiimide, and 150 ml of ethyl acetate.
Yield : (after chromatographic purification) 12 g of 4-difluoromethoxy-2-N-di-tert-pentylphenoxybutyl-carbamoyl-naphthol melting at 99°C.
Representative examples of novel cyan-forming couplers corresponding to the above general formulae I and II are given in the following table 1, the symbols used therein having the significance as defined hereinbefore. It is to be understood, however, that the invention is not limited to these specified couplers.
As illustrated in the above reaction schemes and preparation examples, the « ,d -fluorinated alkoxy coupling off group can be built in in the coupler molecule in but one step by an addition reaction. This contributes greatly to the economical accessability of the novel couplers. Moreover, the reaction sequence leading to the couplers of the present invention offers high yields.
The novel 2-equivalent couplers of the present invention can be dispersed successfully in water. Aqueous dispersions of the couplers of the invention can be stored for long periods in normal conditions, which means that they have not to be kept in special cooling rooms. The stability of the aqueous dispersions of couplers according to he present invention has proven to be excellent. The afore-mentioned advantages of the aqueous dispersions of the couplers of the present invention permit the coating of layers containing small amounts of hydrophilic colloid, preferably gelatin. As a consequence of the reduced amount of colloid in the light-sensitive layers, the sharpness of the dye images formed therein is improved.
It has been established also that the sensitometric results obtained with photographic elements comprising couplers according to the present invention are at least as good as those obtained with photographic elements comprising known couplers.
The term "non-diffusing" used herein with respect to couplers has the meaning commonly applied to the term in photography and means that in any practical application migration or wandering of such non-diffusing coupler compound through organic colloid layers such as gelatin layers in an alkaline medium, in the photographic elements of the invention is substantially unexisting.
For the preparation of a photographic multilayer colour element the dispersions of the couplers for each of the colour separation images are usually incorporated into the coating composition of the differently sensitized silver halide emulsion layers. Yet, the couplers can also be added to the coating composition of non-light-sensitive colloid layers that are in water-permeable relationship with the light-sensitive silver halide emulsion layers.
During the preparation of the light-sensitive colour element the non-diffusing cyan-forming couplers corresponding to the above general formulae can be incorporated into the coating composition of the silver halide emulsion 1ayer_° 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 colour couplers, into colloid compositions. The cyan-forming couplers according to the present invention can be dispersed, occasionally in the presence of a wetting or dispersing agent, in a hydrophilic composition constituting or forming part of the binding agent of the colloid layer. Very suitable wetting agents that can be used to disperse the cyan-forming couplers of the invention are the fluorine-containing surface active agents of U.S. Patent Specification no. 4,292,402. For more details about particularly suitable techniques that can be employed for incorporating the couplers of the invention into a hydrophilic colloid layer of a photographic element there can be referred to U.K. Patent Specifications 791,219 - 1,098,594 - 1,099,414 - 1,099,415 - 1,099,416 - 1,099,417 - 1,199,570 - 1,218,190 - 1,297,947, to the U.S. Patent Specifications 2,269,158 - 2,284,887 - 2,304,939 - 2,304,940 - 2,322,027, to the French Patent Specification 1,555,663, and to the Belgian Patent Specification 722,026.
Another technique for incorporating colour couplers is via polymeric latices as described in the published German Patent Applications DE-OS 2,541,230 and 2,541,274.
The cyan-forming couplers according to the present invention can be used in conjunction with various kinds of photographic emulsions. Various silver salts can be used as the light-sensitive salt. For instance silver bromide, silver iodide, silver chloride or mixed silver halides such as silver chlorobromide, silver bromoiodide, and silver chlorobromoiodide can be employed. The couplers can be used in emulsions of the mixed packet type as described in the U.S. Patent Specification 2,698,794, or emulsions of the mixed grain type as described in the U.S. Patent Specification 2,592,243. The colour couplers can be used with emulsions wherein latent images are formed predominantly at the surface of the silver halide crystal or with emulsions wherein latent images are formed predominantly inside the silver halide crystal.
The hydrophilic colloid used as the binder for the silver halide can be e.g. gelatin, colloidal albumin,, zein, casein, a cellulose derivative, a synthetic hydrophilic colloid such as polyvinyl alcohol or poly-N-vinyl pyrrolidone. If desired, compatible mixtures of two or more of these colloids can be employed for dispersing the silver halide.
The light-sensitive silver halide emulsions used in the manufacture of a photographic element according to the present invention can be sensitized chemically as well as optically. They can be sensitized chemically by carrying out the ripening in the presence of small amounts of sulphur-containing compounds such as allyl thiocyanate, allyl thiourea, or sodium thiosulphate. The emulsions can also be sensitized by means of reducing agents e.g. tin compounds as described in the French Patent Specification 1,146,955 and in the Belgian Patent Specification 568,687, imino-aminomethane sulphinic acid compounds as described in U.K. Patent Specification 789,823 and small amounts of noble metal compounds such as gold, platinum, palladium, iridium, ruthenium, and rhodium compounds. They can be sensitized optically by means of cyanine and merocyanine dyes.
The said emulsions can also comprise compounds that sensitize the emulsions by development acceleration e.g. compounds of the polyoxyalkylene type such as alkylene oxide condensation products as described i.a. in U.S. Patent Specifications 2,531,832, 2,533,990, and 4,292,400 in U.K. Patent Specifications 920,637 - 940,051 - 945,340 - 991,608 and 1,091,705 and onium derivatives of amino-N-oxides as described in U.K.Patent Specification 1,121,696.
Further, the emulsions may comprise stabilizers e.g. heterocyclic nitrogen-containing thioxo compounds such as benzothiazoline-2-thione and 1-pheny1-2-tetrazo1ine-5-thione and compounds of the hydroxytriazolopyrimidine type. They can also be stabilized with mercury compounds such as the mercury compounds described in Belgian Patent Specifications 524,121 - 677,337, and in the U.K. Patent Specification 1,173,609.
The light-sensitive emulsions containing the couplers of the present invention may also comprise any other kind of ingredient such as those described for such emulsions in Research Disclosure no. 17643 of December 1978, in particular development-inhibitor-releasing compounds and competing couplers. Such compounds and couplers can be incorporated in layers in water-permeable relationship with the emulsion layers containing the couplers of the present invention.
The non-diffusing cyan-forming couplers of the present invention are usually incorporated into a red-sensitized silver halide emulsion of the photographic multilayer colour element. Such photographic multilayer colour element usually comprises the cyan-forming coupler in (a) red-sensitized silver halide emulsion layer(s), the magenta-forming coupler in (a) green-sensitized silver halide emulsion layer(s), and the yellow-forming coupler in (a) blue-sensitive silver halide emulsion layer(s).
The emulsions can be coated on a wide variety of photographic emulsion supports. Typical supports include cellulose ester film, e.g. cellulose triacetate film, polyvinylacetal film, polystyrene film, polyethylene terephthalate film and related films or resinous materials, as well as paper or coated paper e.g. polyethylene-coated paper, and glass.
For the production of photographic colour images according to the present invention an exposed silver halide emulsion layer is developed with an aromatic primary amino developing agent in the presence of a cyan-forming coupler according to the present invention. All colour developing agents capable of forming a cyan indoaniline dye with the cyan-forming couplers according to the invention, can be utilized as developers. Suitable developing agents are aromatic compounds in particular p-phenylenediamine and derivatives thereof, e.g.
N,N-dialkyl-p-phenylenediamines, N,N-dialkyl-N'-sulphomethyl-p-phenylenediamines, N,N-dialkyl-N'-carboxymethyl-p-phenylenediamines, the sulphonamido- substituted p-phenylenediamines disclosed in US P 2,548,574 and other substituted p-phenylenediamines disclosed in US P 2,566,271.
Typical examples of suitable p-phenylenediamines are N,N-diethyl- p-phenylenediamine, 2-amino-5-diethylaminotoluene, N-butyl-N-sulpho- butyl-p-phenylenediamine, 2-amino-5-[-N-ethyl-N-(B-methylsulphonami- do)-ethyl]-aminotoluene, N-ethyl-N-B-hydroxyethyl-p-phenylenediamine, etc. These developing agents are often used in their salt form e.g. as hydrochloride or sulphate.
The following examples illustrate the present invention.

Example 1

The dispersability of the 2-equivalent cyan-forming couplers comprising an α,α-fluorinated alkoxy-coupling off group according to the present invention was compared with that of analogous cyan-forming couplers differing from the couplers of the present invention only in that they comprise known coupling off groups.
It was therefore tried to make aqueous dispersions of several of the non-diffusing cyan-forming couplers according to the invention and equally of several analogous non-diffusing cyan-forming couplers comprising known coupling off groups according to the following procedure.
2 g of non-diffusing cyan-forming coupler was dissolved in 10 ml of ethyl acetate at room temperature. The resulting solution was added in 10 s to a solution consisting of 16 ml of demineralized water and 2 ml of a 10% aqueous solution of decyl benzene sulphonic acid sodium salt in a high speed stirrer. The mixture was stirred for 5 min to disperse the coupler in the aqueous medium, if at all possible. The ethyl acetate was then removed by evaporation under reduced pressure (27 to 53 kPa) at 65°C. Next, demineralized water was added to a reach a total volume of 20 ml. If succeeded, a 10% aqueous dispersion of coupler was thus obtained, which was fully suited for admixture with the usual light-sensitive silver halide gelatin emulsions.
Whenever an aqueous dispersion was obtained, the average size of the dispersed coupler particles was determined with the COULTER (registered trade mark) NANO-SIZER marketed by Coulter Electronics Ltd., Coldharbour Lane, Harpenden, Hertfordshire, AL 54 UN, United Kingdom.
The measuring principles used in this instrument are those of Brownian Motion and autocorrelation spectroscopy of scattered laser light. The frequency of this Brownian Motion is inversely related to particle size. The instrument also computes a polydispersity index, which is a measure of the width of the size distribution. For instance an index of 0 or 1 would describe an essentially monosized distribution, whereas 8 or 9 would describe a wide range distribution.
The stability of the aqueous dispersions of coupler was checked after long periods of storage (48 h; 7 days; and 28 days) at 40°C. Whenever crystallization appeared to be inexisting after these long periods of storage, the average size of the still dispersed coupler particles and the polydispersity index were determined again as described hereinbefore.
The results of these measurements are listed in the following table 2 (for cyan-forming phenol couplers) and table 3 (for cyan-forming naphthol couplers).
The 5 tested phenol couplers all corresponded to the following structural formula :
wherein X represents hydrogen, chloro, and methoxy (for the 3 comparison phenol couplers A, B, and C respectively) as well as 2-chloro-1,1,2- trifluoroethoxy and 1,1,2,3,3,3-hexafluoropropoxy (for the couplers 3 and 5 according to the invention respectively).
The 6 tested naphthol couplers listed in table 3 corresponded to the following structural formula :
wherein Y represents hydrogen, chloro, 2-p-methylphenylsulphonyl- ethoxy, and N-methoxyethyl-carbamoylmethoxy (for the 4 comparison naphthol couplers D, E, F, and G respectively) as well 1,1,2,3,3,3,- hexafluoropropoxy and 2-chlaro-1,1,2-trifluoroethoxy (for the couplers 18 and 24 according to the invention).
The results listed in tables 2 and 3 clearly demonstrate that the couplers according to the present invention can be dispersed successfully in water -and--that-the-resulting aqueous dispersions remain stable for long periods, so that their admixture with silver halide gelatin emulsions can be delayed optionally for a time.

Example 2

114.6 g of a red-sensitized silver bromoiodide emulsion (2.3 mole % of iodide) comprising per kg an amount of 73.4 g of gelatin and an amount of silver halide equivalent to 47 g of silver nitrate were diluted with 127 g of a 7.5 % by volume solution of gelatin in 100 ml of distilled water.
A dispersion of each of the cyan-forming couplers listed in table 4 hereinafter was prepared as described in example 1 hereinbefore.
Each of the resulting dispersions was added to a red-sensitized silver halide emulsion.
After neutralization of each of the emulsions and addition thereto of the usual additives such as stabilizing agents e.g. 5-methyl-7-hydroxy-s-triazolo[1,5-a]pyrimidine, wetting agents, and hardening agents the necessary amount of distilled water to obtain 575 g of emulsion was added.
Each of the emulsions was coated on film support in a ratio of 150 g per sq.m. Each emulsion layer was dried and covered with a gelatin antistress layer. The dried light-sensitive elements were exposed in a Herrnfeld sensitometer for 1/20th second through a continuous wedge with a constant of 0.30. The exposed elements were colour-developed for 10 min at 24°C with a developer containing as developing agent 2-amino-5-diethylamino-toluene hydrochloride (CD-2), then bleached, fixed, and washed in the conventional way.
Table 4 shows the results of speed, gradation and maximum density (Dmax) obtained with both processed elements, the first of which comprising 2-perfluorobutyroylamino-4-chloro-5-di-n-octyloxyiso- propoxycarbonamido-phenol as comparison coupler H, the second element comprising the phenol coupler 7 according to the present invention.
The speed was measured at 0.2 above fog. The values given for the speed are relative values, a value of 100 being given to the element containing the comparison coupler H, the value 200 corresponding to a doubling of the speed.
It appears from the results in table 4 that the speed, gradation, and maximum density of the photographic element containing the phenol coupler 7 according to the invention are better than those of the element containing the comparison coupler H.

Example 3

A dispersion of each of the cyan-forming couplers listed in table 5 hereinafter was prepared as described in example 1 hereinbefore. Each of the resulting dispersions was added to a red-sensitized silver halide emulsion prepared as described in example 2 hereinbefore. The procedure of treating and coating each emulsion, as well as exposing and developing each element, as described in example 2 hereinbefore, was repeated.
Table 5 shows the results of speed, gradation and maximum density obtained with the 6 processed elements, all of them comprising a different cyan-forming 2-N-di-tert-pentylphenoxybutyl-carbamoyl- naphthol coupler, the difference between these couplers residing only in their coupling off group. These different coupling off groups are indicated in table 5.
For the understanding of the values there can be referred to the explanation given in Example 2.
It appears from the results that the speed, gradation, and maximum density obtained with the elements comprising couplers 18, 24, and 22 according to the present invention, which comprise an α,α--fluorinated alkoxy coupling off group, are at least as good as those obtained with the elements comprising a coupler that has a usual coupling off group (hydrogen or chloro) and are far better than those obtained with the element comprising the known B,B-fluorinated ethoxy coupling off group as described in the published Japanese Patent Application 50-120 334.

Example 4

A dispersion of each of the cyan-forming couplers listed in table 6 hereinafter was prepared as described in example 1 hereinbefore. Each of the resulting dispersions was added to a red-sensitized silver halide emulsion prepared as described in example 2 hereinbefore. The procedure of treating and coating each emulsion, as well as exposing and developing each element, as described in example 2 hereinbefore, was repeated.
Table 6 shows the results of speed, gradation and maximum density obtained with the 3 processed elements, all of them comprising a different cyan-forming N-hexadecylcarbamoyl-naphthol coupler, the difference between these couplers residing only in their coupling off group. These coupling off groups are indicated in table 6.
For the understanding of the values reference is made to the explanation in Example 2.
It appears from the results that the speed, gradation, and maximum density obtained with the elements comprising couplers 23 and 19 according to the present invention, which comprise an α,α-fluorinated alkoxy coupling off group, are as good as those obtained with the elements comprising a coupler that has a usual coupling off group (chloro).

Claims

1. Phenol- or naphthol-type couplers capable of forming a cyan indoaniline dye by reaction with an oxidized aromatic primary amino developing agent and carrying a fluorinated alkoxy coupling off group, characterized in that said fluorinated alkoxy coupling off group is an α,α-fluorinated alkoxy coupling off group.

2. A coupler according to claim 1, characterized in that it corresponds to one of the following general formulae I and II :

wherein :

Y is -CO- or -SU2-,

R represents an alkyl group, an aryl group, or a heterocyclic 5-or 6- membered group, which groups may be substituted,

R² represents a -CF₂R group, R being hydrogen, -CFNCF3, or -CFHC1,

R³ is a ballasting group of sufficient size rendering said coupler non-diffusing in an alkali-permeable layer of a photographic element.

3. Photographic element comprising a light-sensitive silver halide emulsion layer and a coupler according to claim 1 or 2.

4. Photographic multilayer colour element wherein one of the light-sensitive silver halide emulsion layers or a non-light-sensitive water-permeable colloid layer in water-permeable relationship with the light-sensitive silve halide emulsion layer contains a coupler according to claim 1 or 2.

5. Photographic multilayer colour element according to claim 4 comprising at least three silver halide emulsion layers, which are differently optically sensitized, characterized in that a red-sensitized silver halide emulsion layer or a non-light-sensitive colloid layer in water-permeable relationship therewith incorporates said coupler.