US3443943A

US3443943A - Photographic products and processes employing ring - closing 2 - equivalent silver halide developing agents

Info

Publication number: US3443943A
Application number: US655346A
Authority: US
Inventors: Howard G Rogers; Stanley M Bloom
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1967-07-24
Filing date: 1967-07-24
Publication date: 1969-05-13
Anticipated expiration: 1986-05-13
Also published as: FR1574537A; NL6810480A; NL153683B; DE1772930A1; DE1772930B2; DE1772930C3; JPS4832128B1; GB1243047A; BE718506A

Description

United States Patent Int. Cl. G03c 5/54 U.S. Cl. 96-29 26 Claims ABSTRACT OF THE DISCLOSURE Two-equivalent silver halide developing agents capable of undergoing an intramolecular ring closure by oxidation in the development of exposed silver halide are used in novel processes and products for producing monochromatic and multicolor diffusion transfer pictures wherein separate negative and/or positive images are formed.

This invention relates to photography and, more particularly, to compositions and processes useful in the formation of photographic images.

A principal object of this invention is to provide novel silver halide developer compositions and processes employing such novel compositions for the development of silver halide emulsions, wherein the silver halide developing agent is capable of undergoing an intramolecular ringclosure as a result of oxidation.

A further object of the present invention is to provide novel chemical compounds capable of developing silver halide emulsions, said compounds being two equivalent silver halide developing agents.

A further object of the present invention is to provide novel silver halide developing agents particularly useful in diffusion transfer processes, which developing agents are colorless and which form colorless or only slightly colored oxidation products.

A further object of the present invention is to provide novel processes for forming monochromatic as well as multicolor pictures by diffusion transfer practices wherein a single reagent is utilized for the formation of a negative image as well as a positive transfer of said negative image, and wherein the quantity of reagent which is available for positive image formation is controlled as a function of the development of a silver halide latent image, said development providing, as an oxidation product of said reagent, a colored substance which is substantially nondiffusible from the photosensitive stratum, the unreacted reagent being transferred to a superposed printreceiving material, which unreacted reagent, upon subsequent oxidation, provides a colored substance to dye the print-receiving material and form said positive image.

Other objects of the invention will in part be obvious and will in part appear hereafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products and compositions possessing the features, properties, and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

Diffusion transfer processes are well known as effective and convenient means for providing monochromatic, multicolor, and black-and-white photographic reproductions. Of particular interest in this respect are those ice processes generally designated as one-step photographic processes, wherein a photographic processing composition is provided between a photoexposed photosensitive element and a superposed image-receiving element. These elements are maintained in superposed position for a sufficient time to enable image-forming components to transfer in an imagewise manner from the photosensitive element, and sometimes from the layer of processing composition as well, to the image-receiving element. Thereafter, the photosensitive element is separated from the image-receiving element to permit viewing of the transfer image.

The present invention provides a novel class of silver halide developing agents, especially suited for use in diffusion transfer processes of the general type described above. The class may be characterized as consisting of compounds which reduce exposed silver halide to silver and whose oxidation products autoreact by intramolecular cyclization in such a way as to form a new heterocyclic or carbocyclic ring which ring may be aromatic or nonaromatic. For convenience, these silver halide developing agents may be referred to as ring-closing silver halide developing agents.

The ring-closing reaction itself may be achieved by any one of a wide variety of mechanisms initiated by oxidation in a photographic system; the preferred developing agents are hydroquinones and aminophenols having a molecular structure such that internal cyclization will precede external attack by the variety of nucleophillic agents (e.g., hydroxide ions, certain quarternary ammonium salts, etc.) present in a photographic processing composition. In the reduced form (i.e., prior to reduction of silver halide), the ring-closing developing agents of this invention should be sufficiently stable in alkaline solution so as not to undergo oxidation and ring-closure within, or prior to, the processing period except as a consequence of silver halide development.

It has been found that depending in part upon the nature of the newly-formed ring and in part upon the mechanism by which this ring is formed subsequent to the oxidation of the original developing agent, numerous novel and unexpected effects may be achieved. These effects will be discussed in detail hereinafter with particular regard to diffusion transfer photographic processes; however, it will be readily apparent to those skilled in the art that many of these same effects are highly desirable in conventional tray or wet photographic developing processes.

The ring-closing silver halide developing agent may be colorless or colored in its reduced form. The newly formed ring may contribute to the spectral absorption of the oxidation product in such a manner that the oxidation product is substantially colorless or, if originally colored unchanged in color, i.e., there is no significant new absorption in the visible region, or in such a manner that a new chromophore is provided which does absorb in the visible region.

As is well known, black-and-white photographic positive prints may be prepared by silver diffusion transfer processes. In processes of this type, silver transfer images may be produced by contacting a photoexposed photosensitive silver halide element and an image-receptive element with a processing composition containing a silver halide developing agent and a silver halide solvent while said elements are in superposed relation. Examples of photographic materials useful in the production of silver transfer images are described in detail in the literature, e.g., in U.S. Patent No. 2,543,181, issued to Edwin H. Land on Feb. 27, 1951, and U.S. Patent No. 2,647,056, issued to Edwin H. Land on July 28, 1953. In a typical process employing such materials a processing composition containing a viscous aqueous solution of a silver halide developing agent, a silver halide solvent, and an alkali is spread in a uniformly thin layer between the photoexposed gelatino silver halide stratum of a photosensitive element and the silver-receptive stratum of an image-receptive element as said elements are brought into superposed relationship. The elements are maintained in superposed relation for a predetermined period, ordinarily of approximately to 120 seconds in duration, during which exposed silver ha- I lide is reduced to silver and unreduced silver halide forms a water soluble complex silver salt which diffuses through the layer of processing composition to the image-receptive stratum, where, upon being reduced or precipitated to silver, it forms a silver print. At the end of this period, the photosensitive element, preferably together with the solidified layer of processing composition, is stripped from the image-receptive element.

Image-receptive strata of the foregoing type include silver precipitating nuclei dispersed in a macroscopically continuous vehicle comprising subrnacroscopic agglomerates of minute particles of a water insoluble, inorganic, preferably siliceous material such as silica aerogel. This stratum, both before and after receiving the precipitated silver, is extremely thin, preferably being approximately 1 to 8 microns thick. Materials of the foregoing type, including suitable silver precipitating agents, are described in the literature, e.g., in U.S. Patents Nos. 2,698,237 and 2,698,245 issued to Edwin H. Land on Dec. 28, 1954. Other binders or carriers for silver precipitating nuclei include organic polymers such as gelatin and polyvinyl alcohol.

Silver transfer images usually retain traces of the photographic reagents with which 'they have been processed, the continued presence of which may adversely affect their optical properties and/or their stability. It is well known that the quinones formed upon oxidation of hydroquinone and hydroquinone derivatives, which together provide one of the more commonly employed groups of developing agents for silver transfer processes, will undergo various additional reactions, particularly in the presence of alkali and air. These reaction products include humic acids and other colored products. In addition, the quinones may attack the image silver under certain conditions.

For these reasons, it has been common practice to render the oxidation products innocuous or to prevent their subsequent formation by various techniques. One such technique is generally known as print-coating, in which the image is swabbed with a composition which serves to simulaneously wash the developing agent residue from the image-bearing surface and leave behind a protective film which may comprise, for example, gelatin or a suitable plastic. Procedures of this type are described, e.g., in U.S. Patent No 2,719,791, issued Oct. 4, 1955 to Edwin H. Land. However, while such procedures are generally satisfactory, there is always the possibility that traces of developing agent residue may remain behind.

The problems discussed aboveformation of undesirable colored oxidation products and/ or oxidation products which may attack image silver-may be avoided or at least minimized by the use of silver halide developing agents capable of undergoing an intramolecular cyclization reaction which eliminates the quinonoid-type structure usually found in the oxidation products of silver halide developing agents Where the silver halide developing agent is a hydroquinone or an amino-phenol, in intramolecular cyclization can occur between the carbon atom of the oxidation-generated carbonyl of the benzene ring with a substituent so positioned as to form a new six-membered carbocyclic or heterocyclic ring upon cyclization and 1,2-addition. The resultant cyclized oxidation product is no longer a quinone and will not undergo the by-product reactions common to photographically generated quinones.

Hydroquinones are generally considered to be fourequivalent silver halide developing agents, that is, four molecules of exposed silver halide are developed by one molecule of the hydroquinone before the reducing action of the hydroquinone is exhausted. This fact results from the ability of the initially formed quinone to 'hydroxylate to yield a new hydroquinonyl compound which also will reduce silver halide. The intramolecular cyclization with which this invention is concerned yields an oxidation product which is neither a quinone nor a hydroquinone and which is not a new reducing agent for silver halide. It has been experimentally determined, e.g., with the ringclosing developing agent that 1,2-addition occurs and that only two molecules of silver halide are reduced by one molecule of the ringclosing developing agent. Two-equivalent silver halide developing agents have several distinct and important advantags over the conventional or four-equivalent silver halide developing agents. For example, in diifusion transfer processes a given quantity of exposed silver halide will control twice as many molecules of the developing agent. Conversely, 50% less silver halide may be usd to fully develop a given quantity of silver halide developing agent. This not only reduces the cost of the photosensitive element but it makes possible the use of thinner silver halide emulsion layers which in turn permit improved resolving power and image definition.

The two-equivalent property of the ring-closing silver halide developing agents is particularly significant in those embodiments of the invention which involve the control of, or the formation of, an image dye, as described in detail below.

One group of ring-closing hydroquinone developing agents within the scope of this invention may be represented by the general formula:

( 11 CHz-X wherein X is a group which is capable, upon oxidation of the hydroquinone entity to the corresponding qui-none or precursor, of forming a new ring grouping. As examples of groups which may be used as said X, mention may be made of amino, preferably primary amino, and active methylene groups, i.e., a methylene group which is adjacent to a suitable activating group such as carbonyl or sulfonyl. Thus, for example, where X is a primary amino group, the reaction which takes place upon oxidation of the developing agent may be represented as follows:

Another class of ring-closing hydroquinone developing agents may be represented by the general formula:

( OH-Y- X I OH O C eHs-S Oz-C Hz where X is NH and Y is CH i.e., 2,5-dihydroxy- 2'-amino-diphenyl methane, the reaction which takes place upon oxidation results in a colorless oxidation product (3-hydroxy-acridine) and may be represented as follows:

where Y is CR 0, S, Se or NH, it is likely that the developing agent oxidation product, when ring-closed, will be colored. Accordingly such a compound may be employed to form colored transfer images by oxidation and ring closure of imagewise transferred developing agent. Suitable substituents may be present, as is understood in the art, such that the developing agent, in its reduced form prior to ring closure, is difiusible in the processing composition, but the oxidation product is not, the diffusibility difierential being provided primarily as a. result of the newly formed ring. Techniques by which color transfer images may be formed by oxidation after transfer are well known; see, for example, U .8. Patent No. 2,909,430, issued to Howard G. Rogers on Oct. 20, 1959'.

As examples of ring-closing, hydroquinone and amino- NHz I phenol developing agents within the scope of this invention, mention may be made of the following:

( OH GHz-NH2 2 ('2',5 '-dihydroxyphenyl -b enzylamine (2) OH N112 @CIIr-[j 2,5-dihydroxy-2-amino-diphenylmethane (3) m NHz 2,5 -dihydroxy-4-ethyl-2'-amino-diphenylmethane (1)]?! NHz ONE 2 -hydroxy-5-amino-2'-amino-diphenylamine 2-(2'-aminophenoxy)-hydroquinone 2-'(2'-aminophenylthio)-hydroquinone 3,5-dimethyl-2-(2-aminophenylthio)-hydroquinone 2-(2',4'-diamino-phenoxy)-hydroquinone- (9) OH NH;

H3C- S NHz 3,5-dimethyl-4-amino-2-(2-aminophenylthio)phenol (10) on NH;

I OH

3 methyl methoxy-2-(2'-aminophenylthio)-hydroquinone 2-(2,5'-dihydroxybcnzyl)-benzyl-phenyl sulfone 5 -n-hexyl-2- (2-aminophenylthio) -hydro quin one 2-(2-amino-4'-trifiuoromethyl-phenylthioyhydroquinone These developing agents are generally prepared and used as acid salts, preferably the hydrobromide or hydrochloride.

The following examples illustrate the synthesis of ringclosing hydroquinone developing agents and their use in silver transfer photographic processes; the examples are given for purposes of illustration only, and are not intended to be limiting.

EXAMPLE l Ortho bromophenyl benzoquinone (Brassard and lEcuyer, Canadian J. Chem. 36, 700 (1958), 13 g.) was dissolved in ethyl acetate and reduced with hydrogen in the presence of palladium on barium sulphate. The syrupy hydroquinone obtained by removal of solvent was dissolved in a solution of 8.8 g. of sodium hydroxide in 100 cc. of water plus 50 cc. of ethanol, previously deaerated, and kept under nitrogen. The solution was treated with 28 g. of dimethyl sulphate in portions and refluxed one hour. The product was extracted out with ethyl ether, washed with dilute alkali and then water before drying. The ethyl ether was removed and the product crystallized on scratching or trituration with hexane, M.P. 70-71 C. Elemental analysis, assuming C H O Br, gave: calculated: C, 58,.00; H, 4.47; Br, 27.4. Found: C, 57.23; H, 4.44; Br, 27.0.

60 g. of the thus prepared 2,5-dimethoxy-2'-brom0-biphenyl and 21.5 g. of cuprous cyanide were added to 150 cc. ofidimethyl formarnide. After addition of '20 drops of pyridine, the reaction mixture was refluxed 20 hours. The reaction was then poured into a previously prepared solution of 50 g. of ferric chloride dihydrate, 21 cc. of concentrated hydrochloric acid and cc. of water. The mixture was warmed on the steam bath for A2 hour and then extracted with several portions of hot toluene. The combined toluene extract was washed with 6 molar hydrochloric acid, water, cold aqueous 10% sodium hydroxide and water, respectively. After drying, the toluene was concentrated to a small volume and hexane added. 2,5-dimethoxy-2'-cyano-biphenyl (44 g., M.P. 84-86 C.) was obtained; elemental analysis calculated for C H O N showed: Calculated: C, 75.30; H, 5.48; N, 5.85. Foundi C, 75.32; H, 5.57; N, 5.90.

3.4 g. of 2,5-dimethoxy-2'-cyano-biphenyl was dissolved in 100 cc. of ethanol and 9 cc. of concentrated ammonium hydroxide added. The mixture was hydrogenated at 34 pounds per square inch using rhodium on alumina (5% as catalyst. After the theoretical uptake of hydrogen, the solvent was removed and aqueous 6 molar hydrobromic acid added to bring down the crystalline hydrobromide of 2-[2',5-dimethoxyphenyl]-benzylamine (3.8 g., M.P. -200 C.). The compound was taken up in 20 cc. of concentrated hydrobromic acid and refluxed one hour. The hydrobromic acid was removed under nitrogen and the crystalline residue purified by dissolving in ethanol and passing through a pad of Norite. The ethanol solution was concentrated to a small volume and suflicient ethyl acetate added to give two layers. On cooling and scratching, 2.8 g. of 2-[2,5-dihydroxyphenyl]-benzylamine hydrobromide, M.P. 223-6 C. was obtained; elemental analysis calculated as C H O NBr showed: Calculated: C, 52.73; H, 4.77; Br, 27.00. Found: C, 52.69; H, 4.82; Br, 27.26.

On oxidation with silver ion in acetic acid or molecular oxygen in aqueous alkali, a new compound, M.P. 298- 300 C., was obtained in virtually quantitative yield. The compound was independently identified as 3-hydroxyphenanthridine:

EXAMPLE 2 6 g. of 2,5 dimethoxy 2'-carboxydiphenylmethane (Barnett et al., Berichte, 64, 2185) were dissolved in 40 cc. of dry benzene plus 15 cc. of oxalyl chloride and the mixture refluxed for 1 /2 hours. The solvent was removed in vacuo and fresh benzene added and again removed. The residue was dissolved in 25 cc. of acetone, stirred, and cooled to 0-5 C. using an ice-bath. Sodium azide, 1.5 g. in 5 cc. of water was added and the acetone solution stirred 20 minutes. The reaction mixture was poured into ice water and extracted with three portions of benzene. After carefully drying, the benzene extract was refluxed for 8 hours and then taken to dryness, in vacuo. Glacial acetic acid, 50 cc. and 20 cc. of concentrated hydrobromic acid were added and the mixture refluxed for 6 hours. The solvents were removed under nitrogen and the residue crystallized (Norite) from ethanol-ethyl ether to give 4 g. of 2,5-dihydroxy-2'-aminodiphenylmethanehydrobromide M.P. 226230 C.; elemental analysis, calculated for C H O NBr showed: Calculated: C, 52.73; H, 4.72; N, 4.73. Found: C, 52.86; H, 5.06; N, 4.97.

On oxidation with silver ion in acetic acid or molecular oxygen in aqueous alkali a new compound may be isolated in virtually quantitative yield, M.P. 2645 C. The

compound was independently identified as 3-hydroxyacridine:

by comparison with 3-hydroxyacridine synthesized from 7-methoxy-1,2,3,4-tetrahydroacridine by dehydrogenation followed by demethylation.

EXAMPLE 3 Water cc 160 Sodium hydroxide g 8.5 Hydroxyethyl cellulose g 7.3 Sodium thiosulfate g 14.8 Sodium sulfite g 5.2

between said exposed photosensitive element and an image-receiving element of the type used in Type 42 Polaroid Land Film. After an imbibition period of approximately 60 seconds, the image-receiving element was separated and was found to carry a silver transfer image (D 1.65, D 0.58).

EXAMPLE 4 The procedure described in Example 3 was repeated substituting 0.3 g. of 2,5-dihydroxy-2-amino-diphenylmethane hydrobromide. After 60 seconds imbibition, a silver transfer image was obtained (D 1.44, D 0.43).

EXAMPLE 5 A photosensitive element was prepared by coating, at feet per minute, a cellulose acetate support with a 4% solution of cellulose acetate hydrogen phthalate in an 80:20 mixture of methanol and tetrahydrofuran containing 2% by weight of 2,S-dihydroxy-2'-amino-diphenylmethane hydrobromide. Over this coating there was applied, at 10 feet per minute, a coating solution comprising cc. of blue-sensitive silver halide emulsion, 19 cc. of water, and 9 drops in a 1% aqueous succinaldehyde solution. This photosensitive element was exposed to full density and processed by applying a layer approximately 0.0026" thick of a processing composition comprising:

Water cc 100 Potassium hydroxide g 11.2 Hydroxyethyl cellulose g 4.03 Benzotriazole g 3 .5 Zinc nitrate g 0.5 Potassium thiosulfate g 0.5 Lithium nitrate g- 0.5

between said exposed photosensitive element and an image-receiving element as said elements were brought into superposed relationship. [The image-receiving element was prepared in accordance with the disclosure of the copending application of Edwin H. Land, Ser. No. 234,864, filed Nov. 1, 1962, now US. Patent No. 3,362,- 819, and comprised a layer of a 2:1 mixture by weight of polyvinyl alcohol and poly-4-vinyl pyridine, a layer of polyvinyl alcohol, and a layer of a half-butyl ester of poly- (ethylene/maleic anhydride) coated on a baryta paper support.] After an imbibition of one minute, no color was found on the separated image-receiving element, confirming the colorless character of the oxidation product.

EXAMPLE 6 The stain-forming properties of 2 (2.5- dihydroxyphenyl)-benzylamine were compared with those of 4- methylphenyl hydroquinone by exposing a photosensitive silver halide element (of the type used in Type 42 P0- laroid Land Film) in such a way that one-half of the negative was unexposed and the other half was exposed to full density. The exposed photosensitive element was processed by applying a layer approximately 0.0026" thick of the processing composition set forth in Example 5 to which was added 0.9 g. of 2-(2',5-dihydroxyphenyl)-benzylamine hydrochloride and 2.0 g. of N-benzyl-apicolinium bromide, said layer of processing composition being applied between said exposed photosensitive element and an image-receiving element (of the type described in Example 5) as said elements were brought into superposed relationship. After an imbibition period of one minute, the image-receiving element was separated. This process was repeated substituting 0.6 g. of 4-methylphenyl hydroquinone for the 2-(2,5'-dihydroxyphenyl)- benzylamine hydrochloride. A comparison of the two image-receiving elements showed that appreciably more stain resulted from the use of 4'-methylphenyl hydroquinone whose quinone can react with the active methylene quaternary ammonium salt N-benzyl-a-picolinium bro mide to form a colored prdouct.

EXAMPLE 7 The stain comparison tests described in Example 6 were repeated using (a) 0.98 g. of 2-(2',5'-dihydroxyphenyl-4'-ethyl)-benzylamine hydrochloride, and (b) 0.6 g. of 4'-methylphenyl hydroquinone in place of the 2-(2', 5'-dihydroxyphenyl)-benzylamine hydrochloride. The refiection density to visible light of the portion of the imagereceiving element corresponding to the fully exposed area of the photosensitive element was 0.14 for 4-methylphenyl hydroquinone and 0.04 for the 2-(2',5dihydroxyphenyl-4'-ethyl)-benzylamine. The corresponding density readings for the portion of the image-receiving elements corresponding to the unexposed area of the photosensitive element were 0.11 and 0.03.

As is Well known, diffusion transfer photographic processes are by no means restricted to silver transfer, but also may be used for the production of monochromatic and multicolor photographic images. In such processes a sheet of photosensitive material is exposed, the latent image is developed and, concurrent with and under the control of development, an imagewise distribution of ditfusible colorproviding material (dye-image-providing reagent) is formed. At least a portion of this imagewise distribution is transferred by means of an alkaline aqueous processing solution to a superposed image-receiving layer to form a color positive image thereon.

The following examples illustrate the formation of color transfer images by oxidation of imagewise transferred ring-closing developing agents:

EXAMPLE 8 A photosensitive silver halide element prepared by coating a cellulose acetate support, at 10 feet per minute, with a coating solution comprising 4% cellulose acetate hydrogen phthalate and 3% 2-(2-amino phenoxy)- hydroquinone in an :20 mixture of methanol and tetrahydrofuran. Over this coating there was applied, at 10 feet per minute, a coating solution comprising 10 cc. of a blue-sensitive gelatino silver halide emulsion and 10 cc. of water. This photosensitive element was exposed to blue light for 1/100 second and developed by applying a layer approximately 0.0020" thick of a processing composition comprising:

Water cc Potassium hydroxide g 11.2 Hydroxyethyl cellulose g 3.7 N-benzyl-u-picolinium bromide g 4.0 Benzotriazole g 3.5 Zinc nitrate g 0.5 Potassium thiosulfate g 0.5 Lithium nitrate g 0.5

11 Phenyl ethyl alcohol g 2.0 Uvinul 207 (ultraviolet absorber) g 0.5 Arbutin g 0.5

The color of the transfer image is in agreement with the color to be expected of this ring-closed oxidation product.

EXAMPLE 9 A photosensitive silver halide element of the type used in Type 42 Polaroid Land Film was exposed and then developed by applying a layer approximately 0.0026" thick of a processing composition comprising:

2-hydroxy-5amino-2-arnino-diphenylamine g 1.0 Water cc 100 Potassium hydroxide g 11.2 Hydroxyethyl cellulose g 3.4 Benzotriazole g 3.5 N-benzyl-a-picolinium bromide g 2.0 Zinc nitrate g 0.5 Potassium thiosulfate g 0.5 Lithium nitrate g 0.5

between said exposed photosensitive element and an image-receiving element (of the type described in Example 5) as said elements were brought into superposed relationship. After an imbibition period of one minute, the image-receiving element was separated and was found to contain an orange positive image with orange colored highlight area. The orange color of the transfer image is in agreement with the color to be expected of the ringclosed reaction product:

on Iii-Ii NH@ HZNKI ID NHz EXAMPLE A photosensitive element was prepared by dissolving 1.0 g. of 2-(2-aminophenylthio)-hydroquinone in 1 cc. of methanol, 9 cc. of water and drops of saponin. This solution was added to 5 cc. of blue-sensitive silver halide emulsion maintained at 50 C., and the resulting mixture was coated on a cellulose triacetate support at 10 feet per minute. This photosensitive element was exposed and then processed by spreading a layer of processing composition approximately 0.0026 thick between said exposed photosensitive element and image-receiving element (of the type described in Example 5) as said elements were brought into superposed relationship. The processing composition comprised:

Water cc Potassium hydroxide g 11.2 Hydroxyethyl cellulose (high viscosity Natrasol, commercially available from Hercules Powder Co., Wilmington, Del.) g 3.8 Benzotriazole g 3.5 N-benzyl-a-picolinium bromide g 2.0 Zinc nitrate g 0.5 Potassium thiosulfate g 0.5 Lithium nitrate g 0.5

after an imbibition period of one minute, the imagereceiving element was separated and contained a pink positive image. The color of this image was intensified by swabbing with sodium persulfate solution. The image color agrees with that expected of the reaction:

A pink positive image was obtained when the procedure of Example 10 was repeated using 3,6-dimethyl-2- (2'-aminophenylthio)-hydroquinone or using 4-methyl-2- (2'-arninophenylthio)-hydroquinone.

It will be appreciated that the color of the ring-closed oxidation product may vary as a function of the substrate or mordant. Thus, 2,5-dihydroxy-Z-aminodipheny1methane ring closes to an oxidation product which exhibits very little visible absorption in solution but which has been found to give a light yellow image on image-receiving layers of the type employed in Example 5.

Examples 10 and 11 above have illustrated the use of ring-closing developing agents initially positioned in the silver halide emulsion layer. This technique is particularly useful wth ring-closing developing agents which are substantially colorless in the reduced form, or which, if colored, do not significantly absorb light of wavelengths by which the silver halide emulsion is intended to be exposed. If the oxidation product is colored and nonditfusible, one may obtain a colored negative image by removing residual silver halide and developed silver by fixing and silver bleaching techniques well known in the art.

The above discussion and examples have been concerned with ring-closing developing agents which are initially colorless. It is also within the scope of this invention to incorporate a ring-closing developing moiety into a dye molecule, and to employ such ring-closing dye developers in the formation of color transfer images.

The use of dye deve-l0pers-i.e., dyes containing a silver halide developing function-4o form monochromatic and multicolor transfer images is disclosed in US. Patent No. 2,983,606, issued to Howard G. Rogers on May 9, 1961. The provision of a ring-closing moiety in a dye developer may be employed to advantage, as set forth in more detail below, to provide two-equivalent dye developers, to effect bathochromic color shifts in the color of the transferred dye developer, to provide dye developers having a greater differential in their solubility or difiusibility in the reduced as compared .with the oxidized forms, to

provide oxidized dye developers which are unable to participate in reverse redox reactions to regenerate a diffusible species, and to provide dye developers which upon ringclosure split off a diifusible dye moiety.

In carrying out diffusion transfer photographic processes employing dye developers, a photosensitive element containing a silver halide emulsion is exposed and wetted with a liquid processing composition, for example, by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive element superposed, prior to, during, or after wetting, on an image-receiving element. Generally, the photosensitive element contains the dye developer in a layer thereof, and the liquid processing composition is applied to the photosensitive element in a uniform layer as the photosensitive element is brought into superposed position with an image-receiving element. The liquid processing composition permeates the photosensitive element to solubilize the dye developer. As the exposed silver halide emulsion is developed, the oxidation product of the dye developer is immobilized in the developed areas, thereby providing an imagewise distribution of unoxidized, diifusible dye developer dissolved in liquid processing composition. This immobilization is believed to be due, at least in part, to a change in the solubility characteristics of the dye developer upon oxidation, and especially as regards its solubility in alkaline solutions. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer. Under certain circumstances, the layer of the liquid processing composition may be utilized as the image-receiving layer. The image-receiving layer receives a depthwise diffusion, from the emulsion, of unoxidized dye developer, without appreciably disturbing the image-wise distribution thereof, to proivde a reversed or positive, color image of the developed image. The image-receiving element may contain agents adapted to mordant or otherwise fix the diffused, unoxidized dye developer. If the color of the diffused dye developer is affected by changes in the pH of the image-receiving element, this pH may be adjusted in accordance with wellknown techniques to provide a pH affording the desired color. Imbibition periods of approximately one minute have been found to give good results, but this contact period may be adjusted where necessary to compensate for variations in temperature or other conditions. The desired positive image preferably is revealed 'by stripping the image-receiving element from the photosensitive element at the end of the imbibition period.

Dye developers generally have been utilized in the liquid processing composition or in the photosensitive element as mentioned above, for example, in or behind the silver halide emulsion, i.e., a coating or layer of the dye developer is placed on the side of the emulsion adapted to be located most distant from the photographed subject when the emulsion is exposed and preferably also adapted to be most distant from the image-receiving element when in superposed relationship therewith.

Multicolor transfer images may be produced through various methods by using at least two differentially sensitized silver halide emulsions and developing each emulsion in the presence of a differently colored dye developer. One method comprises using integral photosensitive elements and processes such, for example, as those claimed and disclosed in the copending US. application of Edwin H. Land and Howard G. Rogers, Ser. No. 565,135, filed Feb. 13, 1956 and now US. Patent No. 3,345,135, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed with a single processing solution and transferred to a common image-receiving layer. A suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion straturn, each of said emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer, and a yellow dye developer. In one of the presently preferred embodiments of photosensitive elements used in such processes, the dye developer is dis posed in a separate alkali-permeable layer behind the photosensitive silver halide emulsion .with which it is associated.

The preferred dye developers intended for use in the processes of said US. Patent No. 2,983,606 generally have contained a hydroquinonyl or substituted hydroquinonyl moiety to provide the silver halide developing ability. The desired decreased difiusibility of the oxidized dye developer has been primarily a result of the lower solubility in aqueous alkali of quinones as compared with the corresponding hydroquinones. Itis well known, however, that the quinone of one dye developer may be reduced by another dye developer, particularly if the quinone of the second dye developer is less soluble than the first-formed quinone. Such redox reactions adversely affect the color quality of the transfer image by permitting transfer of dye developer molecules which should not transfer. This ability of an oxidized dye developer to be reduced to a diffusible product is greatly reduced by employing a ringclosing hydroquinonyl developing moiety since the resulting oxidation product is less able to participate in redox reactions. In addition, the formation of an additional ring may be used to increase the difiusibility differential between the reduced and oxidized forms of the dye developer. By suitable select-ion of the ring-closing developing moiety based upon the principles and examples given above with respect to initially colorless ring-closing developing agents, one may obtain dye developers having the indicated advantages. In addition, by appropriate selection of the ring-closing developing moiety and oxidizing the transfer-red ring-closing dye developer to cause it to undergo ring closure, the color properties of the transferred dye developer may be modified, e.g., by effecting a bathochromic shift or by increasing the absorption (or saturation) within a portion of the original absorption curve.

Ring-closing dye developers may be represented by wherein D is a dye residue, Q is a group (e.g., as defined above with respect to the developing agents of Formulae A and B) which is capable of reacting with the carbonyl group of the oxidized hydroquinone moiety by 1,2-addition, thereby forming a new ring moiety, and A is a linkin g group. Where it is desired that little or no color change take place in the dye developer as a result of ring-closure, it will be appreciated that the new ring formed should have little or no color of its own or should have a color which is substantially the same as that of the dye entity. In the compounds of Formula D, appropriate selection of linking group A so as to provide an insulating link, i.e., a linking group such as -C H effective to interrupt any system of conjugation or resonance between the ringclosing moiety and the chromophoric or dye portion of the molecule will permit addition control of the color effect resulting from ring-closure. Thus, one may join an orange form-ing ring-closing developer moiety by an insulating linking group to a blue dye moiety to pro- 15 vide a green" image. The selection of suitable linking groups for this purpose will be readily apparent to those skilled in the art. (It will be understood that the hydroquinonyl group may be a part of the dye chromophoric system, i.e., there may be no independent dye residue D.)

It will be appreciated that insofar as the photosensitive element is intended for use only as the precursor for the final image on the image-receiving element, a color change by the dye developer as a result of oxidation and immobilization in the photosensitive element is of little or no consequence. However, if a color change is not desired, as between the original dye color and the desired image color (as where the original dye provides one of the three usually desired subtractive colors, i.e., magenta, cyan or yellow, which comprises the final image on the imagereceiving layer if Q is such that the resulting ring exhibits a distinct color of its own, or if, in compounds of Formula D, A is a noninsulating link) it becomes necessary to provide means in the image-receiving layer which would prevent oxidation, by aerial oxidation or otherwise, of the transferred unoxidized dye developer. One such method is to reduce the pH of the image-receiving layer, prior to exposing the image to air, to a pH substantially precluding oxidation; suitable image-receiving elements for effecting such a pH reduction are disclosed in the copending application of Edwin H. Land, Ser. No. 234,864, filed Nov. 1, 1962.

As mentioned above, it has been common practice to incorporate a dye developer in a layer behind the silver halide emulsion. It has been recognized, however, that it would be desirable in many instances to incorporate the dye devedoper in the same layer as the silver halide emulsion. This is not practical to do if the dye developer is complementary in color to the portion of the spectrum by which the silver halide emulsion is intended to be exposed. It has therefore been proposed, e.g., in U.S. Patent No. 3,307,947, issued Mar. 7, 1967 to Elbert M. Idelson and Howard G. Rogers and in U.S. Patent No. 3,320,085, issued Jan. 18, 1966 to Samual Dershowitz and Robert B. Woodward, to effect a reversible hypsochromic shift in the absorption curve of the dye, as by acylation of a hydroxyl auxochrome or by formation of a lactone which includes a hydroxyl auxochrome. Treatment with alkali after photoexposure hydrolyzes the acyl group or the lactone to regenerate the hydroxy group and the original absorption characteristics of the dye develoyer.

It has now been found that a similar color shift effect may be achieved by employing ring-closing dye developers in which the ring formed as a result of oxidation and intramolecular cyclization has a color of its own which differs from that of the original dye developer or which conjungates with the original dye developer chromophore in such a way as to alter the color thereof in the desired manner. Such dye developers may be represented by Formulae C and D above, where the ring formed by the reaction of the Q with the hydroquinone oxidation product introduces a spectral absorption within the visible region.

In diffusion transfer photographic processes using color-shifting ring-closing dye developers, each dye developer is selected so that the reduced form thereof (i.e., prior to its oxidation in photographic development) exhibits a color other than one of the desired ultimate colors (i.e., magenta, cyan or yellow); the ring-closing moiety is selected such that once oxidation and ringclosure take place, the new ring conjugates with the original dye chromophore to provide magenta, cyan, or yellow, or alternatively, if the new ring is insulated from the original dye chromophore, it has a color of its own which adds to that of the dye chromophore to provide magenta, cyan or yellow. It will also be appreciated that this new chromophore may be effective to provide a product exhibiting absorption across the visible spectrum so as to appear neutral, grey or black to the eye. The selection of suitable dye chromophores, as well as 16 the provision of insulating or noninsulating linking groups, will be readily apparent to one skilled in the art.

It will be appreciated that Where color-shifting ringclosing dye developers are employed to provide color images on the image-receiving sheet, it is necessary that the compound be oxidized thereon following its transfer from the photosensitive element. This may be achieved by simply allowing aerial oxidation to take place on the alkali-wet image-receiving sheet, but preferably, the image-receiving sheet is provided with a suitable oxidizing agent, or treated with an oxidizing agent after separation from the photosensitive element.

Dye developers containing ring-closing developer moieties may be considered to be dyes which contain a silver halide developing group having a substituent so positioned as to undergo intramolecular cyclization, preferably 1,2-addition with a carbonyl group generated by oxidation of the developing agent. The nature of such substituents has been indicated above in connection with ring-closing developing agents which are colorless in the reduced form.

Numerous dye developers have been described in the literature, and one skilled in the art will readily recognize how such known dye developers may be modified structurally to incorporate a ring-closing developing moiety of either the color-contributing type or of the non-color-contributing type. One such technique involves the addition of a suitably substituted mercaptan to a quinone of a dye developer; the preparation of dye developer quinones by selective oxidation is described in U.S. Patent No. 3,116,279, issued to Richard S. Corley on Dec. 31, 1963. The reaction, for example, of mercaptans with quinones to form developing agents, including dye developers, is described in U.S. Patents Nos. 3,009,958, 3,043,690 and 3,173,906, all issued to Milton Green and Howard G. Rogers.

As examples of ring-closing dye developers, mention may be made of:

on on -N=N- s -HCI -om-on NH:

| 0 on, on

on, on NH:

s -on (IJOI-Ia I OH CH3 I I=NNHC0--HB1- born (16) nt lTlH-C O-GFa OH (|)CH3 OCHs HO NH:

OCH; 3011 no N=N-NHC O-Q-qdpsmn H porn 0H l I=N-N-HC OQ-H'Br Cat) The following examples illustrate the use of ring-closing dye developers:

EXAMPLE 12 A photosensitive element was prepared by coating, at 10 feet per minute, a gelatin-subcoated cellulose triacetate base with a coating solution comprising 8 cc. of 2- methoxyethanol, 2 cc. of acetone, 12 drops of dimethyl formamide, 0.2 g. of cellulose acetate hydrogen phthalate and 0.25 g. of the ring-closing dye developer of Formula 18 above. A layer of blue-sensitive emulsion was then applied at 10 feet per minute employing a coating solution comprising 26 cc. of water, cc. of a blue-sensitive gelatino silver halide emulsion, and 4 cc. of a 1% solution of Aerosol OT wetting agent. This photo-sensitive element was exposed to blue light for 1/ 100 second, and processing by spreading a layer of processing composition approximately 0.0032" thick between the exposed photosensitive element and an imagereceiving element as said elements were brought into superposed relationship. (The image-reciving element comprised an image-receiving layer of a 2:1 mixture by weight of polyvinyl alcohol and poly-4-vinyl pyridine, as described in US. Patent No. 3,148,061, issued to Howard C. Hass on Sept. 8, 1964. The processing composition was the same as that used in Example above, except that 0.2 g. of 4-methylphenyl hydroquinone was added.) After an imbibition period of one minute, the image-receiving layer was separated and contained a positive red-brown dye image, D 2.3. (The layer of ring-closing dye developer as coated in the photosensitive element was orange.) Treatment of the transfer image with alkaline persulfate solution changed the image color to an almost neutral black with a slight bluish cast; the resulting image was quite stable in Xenon arc accelerated fading tests. When this experiment was repeated omitting the poly-4-vinyl pyridine from the image-receiving layer, a more light stable black image was obtained. Swabbing of the transfer image with a copper salt instead of alkaline persulfate gave a greenish black image which was very stable.

EXAMPLE 13 The ring-closing developing agent of Formula 15 above gave a violet-brown transfer image when used in a manner similiar to that set forth in Example 12. When the image was acidified with dilute hydrochloric acid, the image was a dark blue. Swabbing with alkaline persulfate solution shifted the image color to a brownish purple. (The dye developer of Formula 16 has had the original color of that of Formula 15 shifted by acetylation with the alkali-removable trifluoracetyl group.)

EXAMPLE 14 Use of the ring-closing dye developer of Formula 17 gave photographic test results very similar to those of the dye developer of Formula 18 in Example 12.

EXAMPLE 15 The ring-closing dye developer of Formula 13 gave a pink-magenta transfer image. In this instance, ring closure creates a pink color as demonstrated in Example 10, and thus there is no significant change in the image color 18 as compared with the same dye developer unsubstituted by the l NHz group.

The ring-closing developing agents discussed above for the formation of color transfer images have had the property of being diffusible in the reduced form and of providing a colored oxidation product by oxidation after transfer to the image-receiving layer. It has also found that the internal cyclization or ring-closing reaction may be utilized to displace or kick-out a portion of the original molecule as a result of oxidation during photographic processing. The displaced portion may be colored and diffusible in the processing composition, in which event it may be transferred imagewise by diffuson to a superposed image-receiving layer to provide a color image. Alternatively, the displaced portion may have served as an anchoring moiety or ballast rendering the ring-closing developing agent initially non-diifusible in the processing composition; in this instance, the remainder of the molecule, including the new ring formed by internal cyclization, should contain solubilizing groups effective to render it diffusible to the image-receiving layer. It will be recognized that either of these types of ring-closing developing agents are types of ring-closing dye developers. Thus they may be considered to be initially nondiifusing splittable ring closing dye developers containing a color-providing moiety and an anchoring moiety, wherein the color-providing moiety is free to transfer as a result of oxidation and intramolecular ring-closure.

The ring-closing reaction involved may be considered to be a 1,4 addition and illustrated as follows (R being as defined below with respect for Formula E):

-NH S Dye I N NH i l HSOr-Dye Ag+ I /C:Ha

The split-off HSO Dye is ditfusible and is transferred to provide the desired transfer image. The splitoff dye is preferably unable to undergo further reaction in the developing photosensitive element and thus will transfer without undesirable participation in side reactions and consequent immobilization.

Such splittable ring-closing dye developers may be represented by the following formula:

wherein A represents the atoms necessary to complete an aromatic ring, e.g., a benzene or naphthalene nucleous, which nucleons may be further substituted;

D is a color-providing moiety, e.g., a complete dye such as a monoazo, disazo or anthraquinone dye, which may, if desired, be metallized in known manner;

Z is an aromatic amino radical, e.g., an anilino substitu- 20 directly or indirectly to a different carbon atom of the aromatic nucleus formed by the A moiety; R is hydrogen, an alkyl such as methyl, ethyl, propyl,

butyl, hexyl, octyl, dodecyl, cyclohexyl, etc.; or a substituted alkyl such as 2-hydroxyethyl, S-dihydroxy- 2 5 propyl, carboxymethyl, carboxyethyl, carboxybutyl, carboxydecyl, hydroxyethyl-ether, polyglycoloxyethyl, furnanemethyl, benzyl, phenylethyl, carboxythenylwhere each R is hydrogen or a lower alkyl radical, and 222 sulfa phenylethyl acylammo phenylethyl incluffing the sklbstituteq denvatlves i More n is a positive integer from 1 to 2 provided that when R 2 3 1 12 bi fi g fgggzliz z gigggf fg gg z 232 or R alone or together comprise one of those named e b i hydroxy-naphthalamino radical, including substituted i: g igg gggigi s gf gg ggggg fig g i i ggi del'lvatlves therfiof havmg a free ,posftlon ortho to 3 15 prises an aromatic nucleus contributing an anchoring sPbstltutFnb Whlch may comm moiety alone or in conjunction with said R and/or R an anchorlng moiety to be descrlbed with more parmoieties, n may be 1, but when R1, R3 or Z alone or Q Y hefemafieri together do not provide such a substituent, n must be 2. Y 15 any substituent which completes or forms an amide with, and reduces the basic character of, the amino vanous Substlments descnbed above P f may group in the 3-position, such as the residue of an acid, P the R, R1, R2, and/01 Y moietles and linking the co1or pwviding moiety D to the 3 nitmgen ifllustrative1 compounds contairfniling tfhtl:l same zirIesdisclosed, atom, and which is ca able of bein eliminated during one of more 0 t 6 0 Owing Patents! the ring formation tc be describe d with more par- 2,414,491, 2,486,440, ,8 2, 2,536,010, 2,543,338, ticularity hereinafter, 3,227,550, 3,227,551, 3,227,552, 3,227,554, 3,243,294

and 3,245,795. 0 0 In general, compounds within the scope of Formula E g g g L. g il {i may be readily synthesized by appropriate reaction bet 5 40w alkyl tween an acid salt of the desired dye and the 3-amino substltuent of the aromatic ring, as follows:

l X in-l) T f R k --Ni H i (XI-l5 -l nun L2 1; Y 9-) Lifl-y-r, z

z X is hydroxy or amino, eg, a primary, secondary or where X is amino, it may be necessary or desirable to tertiary amino substltuent of the formula 40 employ the corresponding l-nitro analogues in the aforementioned reaction followed by reduction, e.g., with hydrogen in the presence of a Raney nickel catalyst, to R8 10m; a l-amlino Igzorgpo unltjil within the scope of Formula may a so e esrra e, in some instances to have wherein each R may be hydrogen, hydrocarbon radithe l-amino substituent protected during reaction, e.g., cal, e.g., alkyl, such as methyl, ethyl, butyl, dodecyl, y an pp p blocking p, to in ure reaction beetc., aryl such as phenyl or naphthyl attached through tween the acid salt and the 3-amino substituent. at carbon atom thereof to the nitrogen atom, a cyclic As was mentioned previously in the description of the alkyl such as cyclopentyl or cyclohexyl, i.e., where both compounds of Formula E, Z is an aromatic amino sub- R s are alkyleue comprising together with the nitrogen stituent, particularly one which is the radical of an aroatom a heterocyclic ring, a substituted alkyl, such as matic primary amino color developer of the p-phenylhydroxyethyl, methoxyethoxyethyl, polyglycoloxyethyl, enediamine and p-aminophenol series, or a naphthylcarboxymethyl, carboxyethyl,ethylcarboxymethyl, benamino radical, including p-aminonaphthylamino and pzyl, phenylethyl, sulfo-phenylethyl, acetylamlinophenylhydroxynaphthylamino analogues thereof, provided that ethyl, succinylamino-phenylethyl furanmethy etc.; or a all of these aromatic substituents have a free osition Substituted W Such as y p Q y p y ortho to theNHsubstituent to permit ring-clos zire and w Z one of fiescnbed amlln? naphthyl' elimination of the color-providing moiety in the desigammo Tadlcak comammg para'ammo Para nated manner. These compounds may be represented by hydroxy substituent, X may be hydrogen; or the sub the following formula: stituent R; R is an anchoring or immobilizing substituent rendering the compound nondifiusible, e.g., higher alkyl such as decyl, dodecyl, strearyl, oleyl, etc. linked directly to the aromatic nucleus or linked indirectly thereto through x an appropriate linking group, e.g., alky1ene-CONH, (F ,L 1 CONH, n-1)? f G coma N Y D etc., an aromatic ring, e.g., of the benzene or naphthalene series, or a heterocyclic ring, which rings may be either bonded to a single carbon atom of the aromatic 1 1' nucleons or fused thereto, i.e., bonded to a pair of (n 1 adjacent carbon atoms, or R may be a plurality of short chain radicals which together provide the anchoring 2 moiety, each of said short chain radicals being linked x 21 wherein X is hydrogen, hydroxy, an amino group of the formula:

such as may be contained by said X moiety, as previously described, or the substituent R provided that one of said X and X moieties must be hydroxy or amino; A represents the atoms necessary to complete a benzene or naphthalene ring, which ring may be further substituted; R has the same meaning as R; n like n, is a positive integer from 1 to 2, provided that when R or R alone or together comprise One of those heretofore named substituents rendering the compound non-ditfusible, either or both n and n may be 1, but when R and R alone or together do not provide such an anchoring moiety, at least one of n and n must be 2.

Where X and/or X is hydroxy, it may be necessary or advisable for the hydroxy moiety to be present as a protected derivative, e.g., as an alkoxy substituent, during coupling, in which event the desired hydroxy analogue may subsequently be obtained by hydrolysis.

The preferred compounds of Formula F may be represented by the formula:

I NH

I OH

wherein the anchoring moiety R or R comprises a long chain amide, e.g., of at least 13 carbon atoms bonded directly to a nuclear carbon atom of the designated benzene nucleus or linked thereto through a phenylene or alkylene linking substituent and nuclear substituted derivatives thereof, e.g., where any of the nuclear carbon atoms of the respective benzene moieties not containing one of the specifically designated substituents may contain a carboxy, alkoxy, alkyl, chloro, hydroxy or an amide substituent, etc.

The preferred subclass of Formula G may be prepared by coupling in the manner described with regard to the broader class of Formula E, followed by dealkylation of the protected hydroxy group. They may also be prepared by coupling of any of the protected derivatives of the known p-aminophenol developers with an ortho-fluoronitrobenzene, followed by reduction of the nitro group, coupling of the dye-containing moiety D-SO -Cl, and hydrolysis in the aforementioned manner, according to the procedure described and claimed in the copending application of Harris L. Curtis, Ser. No. 655,304, filed concurrently.

As examples of useful compounds contemplated by Formula F mention may be made of the following:

O Hr-CHr--Ill-( im- 3 5 1 :11 H? NHSOr- CaH'l-NHOiS Compound 26 contains a color-shifted yellow dye moiety; and Compound 27 contains a color-shifted magenta dye moiety. These compounds upon hydrolysis, e.g., in an alkaline photographic processing fluid, provide yellow and magenta dyes, respectively. Compounds containing such color-shifted dye moieties and the advantages in photography are described in US. Patents Nos. 3,230,085 and 3,307,947, respectively.

It will be observed that the compounds of Formula F, e.g., illustrative Compounds 19-26 contain both a dye moiety and a developing moiety, e.g., an aromatic amino moiety containing a p-hydroxy or p-amino substrtuent. When oxidized .imagewise, as for example, by reducing silver halide to image silver during processing, the oxidation product thereof auto-reacts intramolecularly in the manner previously described to eflect ring-closure and elimination of the dye moiety from the remainder of the molecule.

As these compounds are relatively non-dilfusible in the photosensitive element, they should be employed in systems wherein the oxidizing material, e.g., silver halide reducible to silver, is brought to the compound instead of vice versa.

For example, the non-dilfusible compound may be present in the photosensitive element, e.g., in a layer behind the light-sensitive silver halide emulsion, along with silver precipitating or physical development nuclei (such as pre viously described).

A photosensitive element of this description may comprise a support having thereon a layer of color-providing material of Formula F, e.g., a nonditfusible compound such as one of the illustrative Compounds 1926, and a 7 silver precipitating agent; and a silver halide emulsion layer.

When such a photosensitive element is exposed and then developed with an aqueous alkaline processing composition including a silver halide developing agent (to be described with more particularity hereinafter) and a silver halide solvent, e.g., sodium or potassium thiosulfate, etc., in known manner exposed silver halide is reduced to silver while a soluble silver complex is formed in terms of unexposed and undeveloped areas of the emulsion. This imagewise distribution of soluble silver complex is at least in part transferred into contact with the nondiffusibie color-providing compound where, in the presence of the precipitating nuclei, it is reduced and the splittable ring-closing dye developer in turn oxidized in an imagewise pattern corresponding to unexposed areas of the emulsion. The oxidation product then ring-closes with elimination of diifusible dye which is then free to transfer, by imbibition, to an image-receiving layer to form a positive image thereon.

Two competing reactions are possible in the system just described: (1) the described reaction between the soluble silver complex and the splittable ring-closing dye developer in the presence of silver precipitating nuclei to release an imagewise distribution of ditfusible dye in terms of unexposed areas of the silver halide emulsion layer, and (2) a redox reaction between oxidized silver halide developing agent resulting from the development of exposed silver halide, whereby oxidation and ring closure would release a ditfusible dye in terms of exposed and developed areas of the silver halide emulsion layer. (If the silver precipitating agent is omitted, this redox reaction may be utilized to provide a negative transfer image.) Without appropriate controls, it would be possible for both reactions to occur at the same time so that a uniform transfer of dye occurs in both exposed and unexposed areas, thereby precluding formation of a usable color transfer image. Stated another way, without proper controls, it is possible for transfer in the so-called D and D areas to be of substantially equal density so that no image is obtained or, if a recognizable image is obtained, the image is of undesirable quality.

To obviate this difiiculty so as to obtain a positive color image in the previously described manner, it will, therefore, be apparent that this redox reaction which releases diffusible color-providing material in exposed areas, must be avoided, at least in terms of exposed areas.

One such procedure is to employ as the silver halide developing agent for development of exposed silver halide a relatively immobile developing agent which, at least in its oxidized form, cannot migrate to the ring-closing dye developer in any appreciable amount during processing, i.e., if the oxidized developing agent cannot migrate to contact the ring-closing dye developer, the undesired redox reaction cannot occur. On the other hand, the developing agent must be of sufiicient mobility in the developing composition, at least in its unoxidized form, to develop the silver halide emulsion. Developing agents meeting these qualifications are heretofore known in the art and per se comprise no part of this invention. As examples of such useful developers, mention may be made of hydroquinonyl-type developers containing bulky substituents, e.'g., the triptycene diol developing agents described and claimed in US. Patent No. 3,064,075. It is also contemplated that one may employ developing agents which are irreversibly oxidized as a function of development, i.e., the oxidized form of which is not reducible, e.g., the hydroxylamine developers.

Another'system for obviating the redox reaction is to include the photosensitive element, e.g., in a suitably positioned interlayer, a material which will intercept any oxidized developing agent and render it innocuous before it can migrate to the ring-closing dye developer. Such materials may be defined as being scavengers for oxidized developing agent.

25 As examples of useful scavengers, mention may be made of:

EXAMPLE 16 11.0 g. (0.05 mole) of -nitrodehydrocoumarin was dissolved in 100.0 cc. of methyl Cellosolve. 12.0 g. (0.064 mole) of n-dodecylamine was then added. (The reaction was exothermic and a yellow solid separated out.) The mixture was heated until a clear solution was obtained and then cooled to give 14.0 g. of light yellow crystals, M.P. 168-170 C., an amide of the formula:

A mixture of 16.5 g. (0.0437 mole) of this amide, 7.0 g. (0.056 mole) of dimethylsulfate, 9.2 g. (0.066 mole) of potassium carbonate and 250 ml. of xylene was refluxed overnight. The xylene was then removed by steam distillation and an oily product crystallized on standing. Recrystallization of this product from hexane-chloroform yielded 13.3 g. of light tan needles, M.P. 106-l08 C. of the formula:

13.3 g. of this latter amide was hydrogenated in 95% eth anol in the presence of a Raney-nickel catalyst. The reaction mixture was filtered and the filtrate evaporated. The resulting solid was recrystallized from hexane-ether to ob- 2 6 tain 9 g. of a pure white amine, M.P. 82 C. of the formula:

OCH;

IIIHZ 52 g. (0.145 mole) of the amine prepared in the above manner, 21.0 g. (0.145 mole) of 2-fiuoronitrobenzene, 7.85 g. (0.195 mole) of magnesium oxide and 100.0 ml. of water were heated in a sealed bomb at 180 C. for 18 hours. The contents of the bomb were then filtered and the solid obtained by filtering was stirred in boiling ethyl acetate and filtered. Cooling of the filtrate yielded 40 g. of a light yellow solid, M.P. 125-126 C. of the formula:

OCHQ

10.0 g. of the last-named product was hydrogenated with 5% Pd/BaSo in ethyl acetate to reduce the nitro group to the corresponding amine. The reaction mixture was filtered and the filtrate was then cooled in Dry Ice. Filtration yielded 9 g. of an off-white solid, M.P. 8l83 C. an amine of the formula:

OCH3

4.54 g. (0.01 mole) of this amine and 3.5 g. (0.1 mole) of the sulfonyl chloride of Orange II, a dye of the formula:

were allowed to stand overnight at room temperature in ml. of pyridine. The reaction mixture was then heated on the steam bath for 30 minutes, allowed to cool and poured into 500 ml. of 10% NCl and 50 g. of ice. The resulting solid was filtered and recrystallized from ethyl acetatemethanol to yield 3.6 g. of an orange solid, M.P. 191193 C. of the formula:

OCH3

27 2.6 g. (0. 0034 mole) of this solid in 50 ml. of methylene chloride was reacted with a large excess of boron tribromide in methylene chloride and the reaction mixture was allowed to stand at room temperature overnight. Water was cautiously added and when the reaction was complete, the mixture was stirred for one hour while bubbling nitrogen through the solution. The resulting orange solid was collected by filtration and crystallized from methanol to yield 2.6 g. of the compound, M.P. ISO-151 C. of Formula 25.

EXAMPLE 17 A photosensitive element was prepared by coating onto a cellulose acetate support at a rate of feet per minute a mixture containing 10 cc. of 2% cellulose acetate hydrogen phthalate in acetone, 3.5 cc. of an aqueous colloidal silver mixture containing 0.08 g. of Ag/ 100 cc. of water, and 1.5 g. of the compound of Formula and thereafter coating onto the thus formed layer at the Same rate a mixture containing 4.0 cc. of a panchromatic silver halide emulsion, 24.0 cc. of water and 1.0 cc. of 2% Aerosol O.T. (trademark of American Cyanamid Co. for a wetting agent, dioctyl sodium sulfosuccinate). This photosensitive element was exposed and then developed by spreading between the thus exposed element and a superposed dyeable sheet material at a gap of 0.0024" a processing composition containing the following proportions of ingredients:

Water cc 100.0 Hydroxyethyl cellulose g 3.9 Sodium hydroxide g 5.0 Sodium thiosulfate g 2.0 Triptycene diol g 1.0

After an imbibition period of about two minutes, the elements were separated to reveal a positive dye image.

In the above example, it will 'be observed that a low mobility developing agent triptycene diol was employed to obviate the redox reaction which could occur between a mobile quinone formed by development and the compound of Formula 25 and thus release dye to transfer from exposed and developed areas, thereby obtaining a positive dye transfer image. The following two examples together illustrate the use of a scavenger to remove mobile oxidized developing agent and thus obtain a positive dye transfer image.

EXAMPLE 18 A gelatin layer containing the compound of Formula 25 and the aforementioned colloidal silver precipitating agent was coated on a cellulose acetate support in the manner described in Example 17 to provide a calculated coverage of 136 mgm. per square foot of each of the color-providing compound and the silver precipitating agent. On top of this was applied a layer containing a calculated coverage of 136 mgm. per square foot of gelatin and the same amount of a scavenger of the formula:

Over this was coated a gelatin layer containing a calculated coverage of 100 mgm. per square foot of a bluesensitive silver iodobromide emulsion to provide a photosensitive element. This element was then exposed and developed by spreading between the thus exposed element and a superposed dyeable sheet material at a gap of 28 0.0026" 3. processing composition containing the following proportions of ingredients:

Water cc 100.0

Hydroxyethyl cellulose g 3.9 Sodium hydroxide g 5.0 Sodium thiosulfate g 2.0 Sodium sulfite g 2.0 Metol g 1.6

After an imbibition time of about two minutes, the elements were separated to reveal a positive dye transfer image.

EXAMPLE 19 A photosensitive element prepared in the manner described in Example 18 but containing no scavenger was exposed and developed in the manner described in Example 18.

When the elements were separated following imbibition, dye had transferred in both exposed (from redox reaction with oxidized metol) and unexposed areas (by reaction with transferred silver complex) so that no image formation was observable.

The following example illustrates the concept of employing a relatively immobile developing agent in the photosensitive element to obtain a positive transfer image, it being observed that the same compound employed as the scavenger in Example 18 was here employed as the silver halide developing agent.

EXAMPLE 20 A photosensitive element was prepared as in the foregoing examples except that the compound employed in Example 18 as the scavenger was included in the silver halide emulsion layer at a calculated coverage of 68 mgm. per square foot, the silver halide also being at a calculated coverage of 68 mgm. per square foot. This element was exposed and developed in the manner described in the previous examples with a developing composition containing the following proportions of ingredients:

Water cc 100.0 Hydroxyethyl cellulose g 3.9 Sodium hydroxide g 5 .0 Sodium thiosulfate g 1.0

The gap employed was 0.0016. After two minutes the elements were separated to reveal a positive dye image.

In the preceding description pertaining to the embodiment employing the compounds of Formula F, reference has been made to the use of silver-precipitating nuclei. However, if the color-providing material is a non-discriminating silver halide developing agent, silver-precipitating nuclei need not be employed. As will be apparent to those skilled in the art, the compounds of Formula F may be rendered nondiscriminating by the presence of various substituents on one of the aromatic rings formed by A and A e.g., the substitution of an hydroxyl or amine radical ortho to one of the X and X moieties. The use of such non-discriminating developer-color-providing materials is therefore also contemplated.

In the foregoing description, examples of monoazo, disazo and anthraquinone dyes have been recited. However, it will be appreciated that the split-off color-providing moiety is not restricted to complete dyes such as those disclosed. Included within the field of useful colorproviding materials are those which are initially colorless or of a color other than that ultimately desired in a particular environment, but which provide the desired color during or subsequent to transfer image formation, e.g., upon a change in environment and/ or upon chemical reaction. This change of environment may, for example, be a change in pH, e.g., to an acid environment. Colorproviding materials of this nature include indicator dyes, leuco dyes, and carbinols of basic dyes, as well as incomplete dyes or color formers which may react with another substance, e.g., a diazonium salt, subsequent to transfer to the image-receiving layer, to form a dye image or to modify the color of the transferred moiety; such materials include color couplers of the phenol and naphthol series which will couple with a diazonium salt to form an azo dye. The diazonium salt may be contained on the imagereceiving element to effect azo dye formation following elimination and subsequent transfer thereto of the color coupler, or dye formation may be effected by a separate treatment following transfer. Another class of useful materials of this nature are cyanine dye precursors, e.g., compounds which in alkali provide an active methine coupler.

The above described uses of splittable ring-closing dye developers which upon oxidation and intramolecular ringclosure displace a colored moiety or an anchoring moiety are the subject of the copending application of Stanley M. Bloom and Howard G. Rogers, Ser. No. 655,440 filed concurrently herewith, which application discloses additional examples of such dyes, their synthesis and photographic use. The use of silver ions to react with a compound containing a dye moiety and an immobilizing moiety or anchor and thereby release the dye moiety for diffusion transfer is the subject of the copending application of Howard G. Rogers, Ser. No. 655,502 filed concurrently herewith.

Certain of the ring-closing developing agents herein disclosed, e.g., Compounds 6, 7, 9, 10, 12 and 13, are novel species of the class of developing agents disclosed in U.S. Patent No. 3,043,690, issued to Milton Green and Howard G. Rogers on July 10, 1962. Similarly, Compounds and 8 are species within the class of developing agents disclosed in U.S. Patent No. 3,061,434, issued to Milton Green and Warren E. Solodar on Oct. 30, 1962, and Compound 2 is a species of the class of developing agents disclosed in U.S. Patent No. 3,019,107, issued Jan. 30, 1962, to Elkan R. Blout et al. In each instance, the novel species herein disclosed exhibit the property of undergoing intramolecular ring closure upon oxidation, a property not possessed by any of the compounds specifically disclosed in said patents, i.e., the corresponding metaor para-isomers.

Examples of suitable oxidizing agents for incorporation in image-receiving elements or otherwise used to oxidize transferred image-forming materials may be found in U.S. Patent No. 2,909,430, issued Oct. 20, 1959 to Howard G. Rogers. In general, oxidation is preferably performed at an alkaline pH.

The processes of this invention are especially useful in composite film units intended for use in a Polaroid Land Camera sold by Polaroid Corporation, Cambridge, Mass., or a similar structure, such as the camera forming the subject matter of U.S. Patent No. 2,435,717, issued to Edwin H. Land on Feb. 10, 1948. In general, such composite film units comprise a photosensitive element, such as one of those heretofore described, an image-receiving element and a rupturable pod containing an aqueous alkaline processing composition. The photosensitive element, image-receiving element and pod are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pod may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. In addition to the alkaline material, the processing composition may include additional reagents performing specific desired functions, e.g., viscous film-forming reagents such as hydroxyethyl cellulose, sodium carboxymethyl cellulose, etc., antifoggants, etc., it being understood that any of these ingredients may be present initially in the film unit, in which case the processing composition containing the developer, alkaline material, etc., is formed by contacting the film unit with the aqueous medium therefor. In any event, the processing composition may, if desired, be confined in a frangible container or pod 30 such as described, for example, in U.S. Patents Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

The processing composition may also contain an auxiliary or accelerating silver halide developing agent, as well as an onium salt, particularly a quaternary ammonium salt of the type described in U.S. Patent No. 3,173,- 786, issued to Milton Green and Howard G. Rogers. An ultraviolet absorber may be positioned in the image-receiving element or in the processing composition to provide additional protection against light fading. Numerous image-receiving elements useful in the process of this invention are known in the art, including the patents and applications noted above.

By way of recapitulation, there has been disclosed the use of silver halide developing agents which autoreact to undergo intramolecular ring closure to form a new ring as a result of oxidation during processing of an exposed photosensitive silver halide element. In a particularly useful embodiment, the attacking group is basic, i.e., a primary or secondary amine, or an active methylene group. The attacking group is positioned ortho to a carbonyl group generated by oxidation of a benzenoid hydroxyl group and undergoes a 1.2 addition reaction. Where the new ring is saturated and there is no further substitution, the ring-closed oxidation product, if originally colorless will be substantially colorless or only slightly colored. The more highly substituted the newly formed ring is, the more likey it will be that the ring-closed oxidation will be highly colored. As with all photographic image-forming compounds, the selection of mordant and/or substrate may be utilized to shift the absorption curve. In another useful embodiment, the ring closure may be effected by a 1,4-addition reaction, and a more diffusible moiety, preferably a dye, may be split-out of the original molecule. The ring-closing developing agents may be initially colorless or colored; in either case, oxidation of the imagewise transferred image-forming material may be utilized to create a visible color or to modify an existing color.

Since certain changes may be made in the above products, processes and compositions without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photographic process comprising contacting an exposed silver halide emulsion with an aqueous alkaline solution of a silver halide developing agent containing a hydroquinonyl moiety or an aminophenol moiety to develp exposed silver halide, characterized in that said silver halide developing agent upon oxidation undergoes an intramolecular cyclization to form a new carbocyclic or heterocyclic ring.

2. A process as defined in claim 1, wherein said oxidation product containing said carbocyclic or heterocyclic ring is substantially less soluble in said solution than is said silver halide developing agent.

3. A process as defined in claim 1, wherein said oxidation product is colored.

4. A process as defined in claim 1, wherein said oxidation product is substantially colorless.

5. A diffusion transfer process for forming a colored transfer image comprising the steps of developing an exposed silver halide emulsion in the presence of a silver halide developing agent containing a hydroquinonyl moiety or an aminophenol moiety which upon oxidation undergoes an intramolecular cyclization to form a new ring, forming as a function of said development an imagewise distribution of a ditfusible dye-image-forming reagent selected from the group consisting of (a) an image dye and (b) said silver halide developing agent, and transferring by diffusion at least a portion of said imagewise distribution to a superposed image-receiving layer to provide thereon a colored image.

6. A diffusion transfer process as defined in claim 5, wherein said transferred dye-image-forming reagent is 31 said silver halide developing agent, said process including the steps of oxidizing said transferred silver halide developing agent to effect said intramolecular cyclization thereby forming said color transfer image.

7. A diffusion transfer process as defined in claim 5, wherein said ring-closing silver halide developing agent contains a hydroquinonyl moiety.

8. A diffusion transfer process as defined in claim 5, wherein said ring-closing silver halide developing agent contains an aminophenol moiety.

9. A diffusion transfer process for forming a color transfer image comprising the steps of exposing a photosensitive element containing a silver halide emulsion and a dye developer containing a hydroquinonyl moiety or an aminophenol moiety, said dye developer containing a substituent capable of auto-reacting to eifect an intramolecular cyclization with a carbonyl group formed upon oxidation of said dye developer thereby forming a less diifusible oxidation product, developing said exposed photosensitive element and thereby forming an imagerwise distribution of unoxidized diifusible ring-closing dye developer and transferring at least a portion of said imagewise distribution of unoxidized ring-closing dye developer to a superposed image-receiving layer to provide thereon a color transfer image.

10. A diffusion transfer process as defined in claim 9, including the steps of oxidizing said transferred ringclosing dye developer, thereby effecting a change in the spectral absorption properties of said transferred dye developer.

11. A photosensitive element comprising a support, a layer carried by said support containing a photosensitive silver halide emulsion and a layer on said support containing a silver halide developing agent containing a hydroquinonyl moiety or an aminophenol moiety and which upon oxidation is capable of undergoing an intramolecular cyclization to form a new carbocyclic or heterocyclic ring.

12. A photosensitive element as defined in claim 11, wherein said ring-closing silver halide developing agent is contained in the layer containing said silver halide emulsion.

13. A photosensitive element as defined in claim 11, wherein said ring-closing silver halide developing agent contains a hydroquinonyl moiety.

14. A photosensitive element as defined in claim 11, wherein said ring-closing silver halide developing agent contains an aminophenol moiety.

15. A photosensitive element as defined in claim 11,

32 wherein said ring-closing silver halide developing agent is a dye.

16. A photosensitive element as defined in claim 11 is associated with an image-receiving layer so positioned as to be capable of receiving by diifusion transfer an imagewise distribution of an image-forming reagent.

17. A photosensitive element as defined in claim 11, wherein said developing agent is 2-(2',5 dihydroxyphenyl)-benzylamine.

18. A photosensitive element as defined in claim 11, wherein said developing agent is 2,5-dihydroxy-2-aminodiphenylmethane.

19. A photosensitive element as defined in claim 11, wherein said developing agent is 2-hydroxy-5-amino-2- aminodiphenylamine.

20. A photosensitive element as defined in claim 11, wherein said developing agent is 2-(2-aminophenoxy)- hydroquinone.

21. A photosensitive element as defined in claim 11, wherein said developing agent is 2-(2-aminophenylthio)- hydroquinone.

22. A photographic process as defined in claim 1, wherein said developing agent is 2-(2',5 dihydroxyphenyl) -benzylamine.

23. A photographic process as defined in claim 1, wherein said developing agent is 2,5-dihydroxy2-aminodiphenylmethane.

24. A photographic process as defined in claim 1, wherein said developing agent is 2-hydroxy-5-amino-2'- amino-diphenylamine.

25. A photographic process as defined in claim 1, wherein said developing agent is 2-(2'-aminophenoxy)- hydroquinone.

26. A photographic process as defined in claim 1, wherein said developing agent is 2-(2-aminophenylthio)- hydroquinone.

References Cited UNITED STATES PATENTS 3,043,690 7/1962 Green et a1. 9629 FOREIGN PATENTS 731,301 6/1955 Great Britain.

NORMAN G. TORCHIN, Primary Examiner.

A. T. SUROPICO, Assistant Examiner.

US. Cl. X.-R. 96-66 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,443,943 May 13, 1969 Howard G. Rogers et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 58, "hereafter" should read hereinafter Column 3, line 64, after "agents" insert a period; line 65, "in" should read an Column 4, line 25, "advantags" should read advantages Column 5, lines 3 to 9, the formula should appear as shown below:

X :H i Y same column 5 lines 25 to 36 the right-hand formula should appear as shown below:

C H5-SO2 same column 5, lines 26 to 34, the left-hand portion of the left-hand formula should appear as shown below:

Column 7, line 72, "58, .00" should read 58.00 Column 15, line 32, "devedoder" should read developer line 38, "No. 3,320,085" should read No. 3,230,085 line 52, "conjungates" should read conjugates Column 17, line 38, "4-methy1- phenyl" should read 4 methy1pheny1 Column 19, line 26,

at the end of the formula insert etc. line 72, "nucleous" should read nucleus Column 20, line 8, "furnanemethyl" should read furanemethyl line 8, "carboxythenylethyl" should read carboxyphenylethyl line 23, 2,552,802" should read 2,522,802 Column 30, lines 48 and 49, "develp" should read develop line 51, cancel "new"; line 66, "to form a new ring" should read to form a carbocyclic or heterocyclic ring Column 31, line 37, "to

form a new carbocyclic" should read to form a carbocyclic Signed and sealed this 13th day of October 1970.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents