GB2109368A - Substituted benzodioxin 2- equivalent cyan-forming couplers and photographic elements containing them - Google Patents

Abstract

2-Equivalent cyan forming couplers corresponding to the formula: <IMAGE> wherein Y is hydrogen or a halogen atom, X stands for -CO-, -SO2-, -COCOO-, or -CONH-, and R is an organic ballasting group rendering said couplers non-diffusing in an alkali-permeable layer of a photographic element, can be incorporated in (a) red-sensitized silver halide emulsion layer(s) of a photographic multilayer colour element or in a non-photosensitive colloid layer in water-permeable relationship with the red-sensitized emulsion layer(s). 11 monomeric couplers are exemplified, some of which are stated to be useful in preparing polymeric couplers by emulsion polymerisation.

Description

SPECIFICATION Novel 2-equivalent cyan-forming couplers and photographic elements containing them The present invention relates to novel cyan-forming 2-equivalent couplers, to the use thereof in the production of photographic colour images, and to photographic elements containing such colour couplers.

It is known that for the production of a photographic colour 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 colour coupler, which enters into reaction with the oxidized developing substance to form a dyestuff 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) red-sensitized silver halide emulsion layer(s), (a) green-sensitized silver halide emulsion layer(s), and (a) blue-sensitive silver halide emulsion layer(s), wherein upon colour development, by the use of appropriate colour couplers, cyan, magenta, and yellow dyestuff images are formed respectively.

Fundamental difficulties affecting the subtractive three-colour photographic process are concerned with the sensitometric properties and with the stability of the dyes, which make up the coloured photographic images, against light, heat, and humidity.

Another frequently occurring problem is the insufficient or incomplete bleaching of the metallic silver formed during development, especially in the case of persulphate bleaching, which type of bleaching is increasingly used nowadays for ecological reasons.

It is therefore an object of the present invention to provide novel cyan-forming 2-equivalent couplers. A further object is to provide photographic colour elements containing said novel cyanforming 2-equivalent couplers which yield favourable sensitometric properties as well as dye images of high stability to light, heat, and humidity, and which allow complete bleaching of the metallic silver formed during development.

Another object of the invention is to produce a photographic colour image by development of a a photographic colour element containing said novel cyan-forming 2-equivalent couplers.

Other objects of the invention will become apparent from the disclosure hereinafter.

The above objects are accomplished with the aid of novel cyan-forming 2-equivalent phenol couplers carrying an ethylene-dioxy group linked to the 4,5-positions of the phenol, which upon coupling with the oxidized developing substance - instead of splitting off as is usual in the case of 2-equivalent couplers - remains permanently attached to the resulting indoaniline dye to provide high coupling activity and favourable sensitometric properties, allowing complete bleaching of the silver formed development and yielding cyan indoaniline dyes that are very stable to light, heat, and humidity.

According to the present invention there are provided novel cyan-forming 2-equivalent phenol couplers capable of forming a cyan indoaniline dye by reaction with an oxidized aromatic primary amino developing agent, said couplers corresponding to the following general formula.

wherein Y Y represents hydrogen or a halogen atom e.g. chlorine and fluorine X represents a member selected from the group consisting of -CO-, -SO2-, -COCOO- and -CONH-, R represents an organic ballasting group rendering said coupler non-diffusing in an alkalipermeable layer of photographic element, and containing at least 8 carbon atoms e.g. an aliphatic or aromatic hydrocarbon group, which may be substituted, in particular, an alkyl, alkenyl, aryloxyalkyl, aryl, or alkoxyaryl group.

The present invention also provides a photographic colour element comprising a colour coupler as defined above, in particular a colour element comprising at least three silver halide emulsion layers, which are differently optically sensitized and wherein the novel 2-equivalent colour coupler(s) as set forth above is (are) present in (a) red-sensitized silver halide emulsion layer(s) or in (a) non-light-sensitive colloid layer(s) in water-permeable relationship therewith.

Table 1

Coup~ Y X | R Yield Melting ler in at OC 1 H -CO- -CH(C2H5)-O-#-t-C5H11 70 150 t-C5H11 2 C1 idem idem 61 147 3 H idem -CH(C2H5)-0-# 9 45 86 C15H31 4 H idem -C1H-(CH2)7-CH=CH-C7H15 43 71 CH2COOH 5 H -S02- -C16H33 44 88 6 H -CO- -#-0-C16H33 35 113 7 H -SO2- idem 30 127 8 H -CONH- -C18H37 67 108 9 H -COCOO- -CH2CH2O-#-t-C5H11 46 155 t-C5H11 10 H -CO- -C(CH3)=CH2 55 150 11 C1 idem idem 37 1 75 Representative examples of novel cyan-forming colour couplers corresponding to the above general formula are given in table 1. However, it is to be understood that the invention is not limited to these specifically mentioned colour couplers. The symbols used in Table 1 are those used in the general formula.

The above compounds can be prepared as described in the illustrative preparations herein- after.

Preparation 1; coupler 1 a) 6-nitro- 7-benzyloxy-benzodioxin 81 g (0.75 mol) of benzylalcohol was added with thorough stirring to a suspension of 36 9 of sodium hydride (50% in oil: 0.75 mol) in 700 ml of dimethylacetamide. As a consequence of the evolution of hydrogen a strong frothing was occasioned. After 30 min a grey suspension remained, which after cooling to 10 C was added portion-wise in 15 min to a solution in 400 ml of dimethylacetamide of 113 g (0.5 mol) of 6,7-dinitro-benzodioxin prepared as described in the Research Disclosure 20 219 of February 1981, page 91, column 1.The temperature rose to 55 C. Th mixture was stirred for 30 min at 55 C. The brown-red reaction mixture obtained was poured out in a mixture of 1 kg of ice and 1 1 of water and neutralized with 50 ml of acetic acid. The resulting precipitate was rinsed with water, dried, and recrystallized from 2methoxyethanol. Yield 101 g (70%) of 6-nitro-7-benzyloxy-benzodioxin melting at 11 9'C.

b) 6-amino- 7-hydroxy-benzodioxin hydrochloride 97.5 g (0.34 mol) of 6-nitro-7-benzyloxy-benzodioxin, 17 ml of Raney nickel, and 800 ml of 2-methoxy-ethanol were placed in an autoclave. Reduction was carried out at I initial pressure of 10 MPa. After agitation for 4 h the reduction and debenzylation came to an end. The Raney nickel was filtered off. The solution was poured out in 250 ml of ethanolic hydrogen chloride (5M) and the mixture was then concentrated by evaporation. The dry product was dissolved in a mixture of 200 ml of ethanol and 50 ml of ethanolic hydrogen chloride, precipitated with 1 1 of isopropyl ether, filtered off, and dried. Yield: 53 g (75%) of 6-amino-7hydroxy-benzodioxin hydrochloride melting at approximately 85 with decomposition.

c) Coupler 1 20.35 g (0.1 mol) of 6-amino-7-hydroxy-benzodioxin hydrochloride, 25.2 g (0.3 mol) of sodium hydrogen carbonate, and 33.8 g (0.1 mol) of -(2,4-di-tert-pentylphenoxy) butanoyl chloride were stirred in 250 ml of acetonitrile for 1 h at 35-40 C. The reaction mixture was poured out in 0.5 1 of icewater and 50 ml of hydrogen chloride (2M). The resulting precipitate was filtered off, rinsed with water until free from acid, dried, and recrystallized from 150 ml of methanol Yield : 32.8 9 of coupler 1.

Preparation 2 : coupler 2 A suspension of 16.5 g (0.035 mol) of coupler 1 and 4.8 g (0.036 mol) of Nchlorosuccinimide in 150 ml of carbon tetrachloride was stirred for 2 h at 15-20 C.

Succinimide was filtered off and the filtrate was rinsed with water. After drying over magnesium sulphate the organic solvent was evaporated. The resulting oil was dissolved in a mixture of methanol and water (4:1) Yield 10.5 g of coupler 2.

Preparation 3 : coupler 5 16.3 g (0.05 mol) of n-hexadecylsulphochloride was added to a solution of 10.2 g (0.05 mol) of 6-amino-7-hydroxy-benzodioxin hydrochloride (see preparation 2b) and 8 ml (0.105 mol) of pyridine in 100 ml of acetonitrile. The mixture was kept at 40 C for 1 h and then poured out in 500 ml of icewater and 100 ml of 1 N hydrochloric acid. The resulting precipitate was rinsed with water until free from acid and recrystallized twice from methanol. Yield : 11.5 g of coupler 5.

Preparation 4 : coupler 8 40.4 9 (0.2 mol) of 6-amino-7-hydroxy-benzodioxin hydrochloride (see preparation 2b) and 21 g (0.25 mol) of sodium hydrogen carbonate were stirred for 15 min in 500 ml of acetonitrile. An amount of 70 ml (0.22 mol) of octadecyl isocyanate was added thereto and the whole was stirred for 1 h at room temperature. The reaction mixture was poured out in a mixture of 2500 ml of icewater and 100 ml of 5N hydrochloric acid. The resulting produce was rinsed with water until free from acid and recrystallized from 750 ml of ethanol. Yield : 62 g of coupler 8.

Preparation 5: coupler 10 A suspension of 36.5 g (0.18 mol) of 6-amino-7-hydroxy-benzodioxin hydrochloride (see preparation) 2b and 21.2 g (0.20 mol) of sodium carbonate in 200 ml of acetonitrile and 90 ml of dimethylformamide was stirred for 10 min at 20 C. An amount of 18.2 ml of methacryloyl chloride (95 %) was added in 15 min and the whole was stirred for 30 min. The reaction mixture was poured out in a mixture of 1 1 of icewater and 10 ml of 1 N hydrochloric acid. The resulting precipitate was dried and then stirred in 300 ml of isopropyl ether. Yield : 23.5 9 of coupler 10.

Preparation 6 : coupler 11 A suspension of 23.5 9 (0.1 mol) of 6-hydroxy-7-methacrylamido-benzodioxin (coupler 10) and 13.4 g (0.1 mol) of N-chlorosuccinimide in 100 ml of dichloromethane was stirred for 1 h at room temperature. Succinimide was then filtered off and the filtrate was concentrated by evaporation. The resulting oil was crystallized twice from a mixture of 5 parts of water and 1 part of ethanol. Yield 10 g of coupler 11.

Couplers 10 and 11 are suited for use as polymeric couplers in the form of a latex obtained by emulsion polymerization techniques with the aid of the usual addition polymerization initiators. Interesting polymerization techniques have been described e.g. in the Belgian Patent Specification 669,971, according to which latices are formed of polymeric colour couplers by emulsion polymerization in aqueous gelatin, and in the United Kingdom Patent Specification 1,130,581 according to which latices are formed of polymeric couplers by emulsion polymerization in water, as well as in the United Kingdom Patent Specification 1,453,057, according to which latices are made of polymeric colour couplers and competing couplers wherein the polymer particles are internally stabilized in the aqueous colloidal dispersion by a polymerically combined emulsifier.

Examples of polymerization initiators and suitable solvents as well as information relating to the formation of the initial emulsions and/or suspensions have been set forth in the above mentioned patents.

The non-diffusing non-polymeric cyan-forming couplers according to the present invention comprise in their molecule an organic group sufficiently large to prevent the colour coupler from wandering from the colloid layer, in which the colour coupler has been incorporated, to another colloid layer.

For the preparation of a photographic multilayer colour element the non-diffusing colour couplers for each of the colour separation images are usually incorporated into the coating compositions of the differently sensitized silver halide emulsion layers. Yet, the non-diffusing colour couplers can also be added to the coating compositions of non-light-sensitive colloid layers that are in water-permeable relationship with the light-sensitive silver halide emulsion layers.

During the making of the light-sensitive colour element the non-diffusing cyan-forming couplers according to the above general formula can be incorporated into 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 colour couplers, into colloid compositions.

The non-polymeric cyan-forming couplers according to the 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 colour couplers of the invention are the fluorine-containing surface active agents of European Patent Application no. 80/200 101.6, interesting representatives of these fluorine-containing surface-active agents being 2, 3.4-tris-(2 H-hexafluoropropyloxy) benzene sulphonic acid and the salts thereof e.g. the sodium salt. For more details about particularly suitable techniques that can be employed for incorporating the colour 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 1,199,415 - 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 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 and in the Research Disclosure no. 18 815 of December 1979.

The cyan-forming couplers according to the invention can be used in conjunction with various kinds of photographic emulsions for the production of photographic colour images.

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 vehicle 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 making of photographic elements 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 sulphurcontaining 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 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 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, in U.K.

Patent Specifications 920,637 - 940,051 - 945,340 - 991,608 and 1,091,705, onium derivatives of amino-N-oxides as described in U.K. Patent Specification 1,121,696, and thioethers as described in the U.K. Patent Application 79/33608.

Further, the emulsions may comprise stabilizers e.g. heterocyclic nitrogen-containing thioxo compounds such as benzothiazoline-2-thione and 1-phenyl-2-tetrazoline-5-thione and compounds of the hydroxytriazolopyrimidine type. They can also be stabilized with an aromatic or heterocyclic mercapto compound as described in the U.K. Patent Application 80/39457 or 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 colour couplers of the invention may also comprise any other kind of ingredient such as those described for such emulsions in Research Disclosure no. 17 643 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 for forming one of the differently sensitized silver halide emulsion layers of a photographic multilayer colour element e.g. positive motion-picture film.

Such photographic multilayer colour element usually comprises a support, (a) red-sensitized silver halide emulsion layer(s) with cyan-forming coupler, (a) green-sensitized silver halide emulsion layer(s) with (a) magenta-forming coupler, and (a) blue-sensitive silver halide emulsion layer(s) with yellow-forming coupler. They can also be used for the production of radiographic colour images as described e.g. in the U.S. Patent Specifications 3,721,823; 3,734,735; 3,820,991; 3,809,906; and 4,049,454. Radiographic colour elements, which can comprise at least one colour coupler according to the present invention for the production of monochromic radiographic images, optionally together with a silver image, are described in the above U.S. Patent Specifications.Radiographic colour elements preferably comprise colour couplers in dispersed state as referred to hereinbefore or in the form of polymer latices as also referred to hereinbefore. The silver halide emulsions are silver bromoidide emulsions, which may contain minor amounts of non-image forming silver chloride or they are silverchlorobromide (iodide) emulsions containing at least 15% and preferably at least 50 mole % of chloride. These radiographic colour materials can be used in combination with UV-, blue- or green-emitting screens.

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 colour 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 colour coupler according to the present invention. All colour developing agents capable of forming azomethine dyes 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-phenylenediamine, N, N-dialkyl-N '-carboxymethyl-p-phenylenediamine, the sulphonamido-substituted p-phenylenediamines disclosed in the U.S. Patent Specification 2,548,574 and other substituted pphenylenediamines disclosed in the U.S. Patent Specification 2,566,271.

Typical examples of p-phenylenediamines are N, N-diethyl-p-phenylenediamine, 2-amino-5 diethylaminotoluene, N-butyl-N-sulphobutyl-p-phenylenediamine, 2-amino-5- [ N-ethyl-N-(ssme- thylsulphonamido)-ethyl] -aminotoluene, N-ethyl-N-P hydroxyethyl-p-phenylenediamine, etc.

These developing agents are often used in their salt form e.g. as hydrochloride or sulphate.

The following example illustrates the present invention.

Example 114.6 g of a red-sensitized silver bromoiodide emulsion (2.3 mole % of iodide) comprising per kg an amount of 73.4 9 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 cyan-forming colour coupler was made by dissolving 0.006 mole of the colour coupler as specified in the table hereinafter in 16 ml of ethyl acetate and 2 g of dibutyl phthalate, dispersing the resulting solution in 100 ml of a 5% by volume aqueous solution of gelatin containing 0.4 g of the sodium salt of dodecylbenzene sulphonic acid by means of an ultrasonic power generator, and eliminating the ethyl acetate by evaporation under reduced pressure.

The resulting dispersion was added to the red-sensitized silver halide emulsion.

After neturalization of the emulsion and addition thereto of the usual additives such as stabilizing agents e.g. 5-methyl-7-hydroxy-s-triazolo [ 1 ,S-a ] pyrimidine, wetting agents, and hardening agents the necessary amount of distilled water to obtain 575 g of emulsion was added.

The emulsion was coated on a film support in a ratio of 150 g per sq. m. The emulsion layer was dried and covered with a gelatin antistress layer. The dried emulsion material was cut and the resulting strips were exposed in a Herrnfeld sensitometer for 1 /20th second through a continuous wedge with a constant of 0.30. The exposed strips were colour-developed, bleached, fixed, and washed in the conventional way using two different types of developers viz.

- the first developer containing as developing agent 2-amino-5-diethylamino-toluene hydrochloride (CD-2); development time : 10 min; temperature of development : 24 C, - the second developer containing as developing agent N, N-diethyl-p-phenylene diamine sulphate (TSS); development time: 4 min; temperature of development : 25 C.

In the table 2 hereinafter the values of speed, gradation and maximum density obtained after processing with the above-mentioned 2 developers of the strips of red-sensitized emulsion containing the cyan-forming couplers are given.

Table 2: sensitometric results.

Cyan-forming CD-2 TSS coupler in red sensitized speed gradation Dmax speed gradation Dmax emulsion Comparison 100 1.3 2.5 100 1.9 2.9 coupler A coupler 2 105 1.8 2.8 110 2.8 4.0 coupler 3 100 1.4 2.3 115 1.7 2.7 coupler 7 120 1.6 2.0 115 2.3 2.5 "Comparison coupler A corresponds to the following structural formula:

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 emulsion containing the comparison coupler A.

It appears from the results in table 2 that the speed and gradation obtained with the red sensitized emulsion containing the cyan-forming couplers 2, 3, and 7 are at least as good as those obtained with the comparison coupler A and in general are even better than those obtained with coupler A. The values of maximum density appear to be good as well.

The stability of the dyes obtained against light, heat, and humidity were found to be good also.

It was experienced also that during the bleaching step with persulphate, the developed silver was bleached out completely.

Claims (7)

1. 2-Equivalent phenol coupler capable of forming a cyan indoaniline dye by reaction with an oxidized aromatic primary amino developing agent, characterized in that said coupler carries an ethylene-dioxy group that is linked to the 4, 5-positions of the phenol.

2. A 2-equivalent phenol coupler according to claim 1 characterized in that it corresponds to the general structural formula:

wherein: Y represents hydrogen or a halogen atom X represents a member selected from the group consisting of -CO-, -SO2, -COCOO-, -CONH-, and R represents an organic ballasting group rendering said coupler non-diffusing in an alkalipermeable layer of a photographic element, and containing at least 8 carbon atoms.

3. A 2-equivalent phenol coupler according to claim 2, characterized in that R is an aliphatic or aromatic hydrocarbon group, which may be a substituted group.

4. Photographic element comprising one or more photosensitive silver halide emulsion layers containing a colour coupler according to any of claims 1 to 3.

5. Photographic colour element containing in at least one of the photosensitive silver halide emulsion layers or in a non-photosensitive water-permeable colloid layer in water-permeable relationship with said photosensitive silver halide emulsion layer(s) a colour coupler according to any of Claims 1 to 3.

6. Photographic colour element 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-photosensitive colloid layer in water-permeable relationship therewith incorporates at least one colour coupler according to any of claims 1 to 3.

7. Radiographic colour element for the production of monochromic colour images, characterized in that said element comprises at least one colour coupler according to any of claims 1 to 3.