UNITED STATES PATENT OFFICE 2,449,244 Thioindoxyl Couplers for COLOR PHOTOGRAPHY Fritz W
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Patented Sept. 14, 1948 2,449,244 UNITED STATES PATENT OFFICE 2,449,244 THIoINDoxYL couPLERs FoR COLOR PHOTOGRAPHY Fritz W. H. Mueller and Abraham Bavley, Bing hamton, N.Y., assignors to General Aniline & - Film Corporation, New York, N. Y., a corpora tion of Delaware No Drawing. Application January 25, 1945, Serial No. 574,619 6. Claims. (CI, 95-6) 1. 2 This invention relates to the production of col the following specification in which its preferred ored photographic images by color-forming de details and embodiments are described. velopment, and more particularly to arylaldehyde This invention is based on the discovery that derivatives bridged by a single methine chain as arylaldehyde derivatives which are linked to color-forming couplers therefor. gether by a single methine (-CHF) chain in It is known that compounds containing meth the reactive coupling position normally occupied ylene groups whose hydrogens are activated by by the arylimino group during azomethine dye other substituents in the molecule, such as car formation will react in color-forming develop bonyl (CO) or nitrile (CN), readily combine di ment with the oxidation product of the developer rectly with arylnitroso compounds or indirectly 0 in the absence of sodium sulfite or sodium bisul with primary aromatic amines in the presence of fite, in the usual manner, to form dye images. It an oxidizing agent, through intermediate oxidiza has been found that the methine group of the tion products, to form. azomethine dyes. For ex color-former is displaced by the arylamino group ample, l-phenyl-3-methyl-5-pyrazolone reacts during dye image formation. This discovery is with p-nitroso-dimethylaniline to form the azo 5 surprising and wholly unexpected since, ingen methine dye, -phenyl-4-dimethyl-aminophenyl eral, methine linkages are not readily displaced imino-3-methyl-5-pyrazolone. Alternatively, the by other groups in the absence of a reducing same dye results from the reaction of the above agent. mentioned pyrazolone with p-aminodimethylani The arylaldehyde derivatives bridged by a single line in the presence of an oxidizing agent such as, "20 methine chain of the present invention, are rep for example, potassium persulfate. resented by the following general formula: . The ability of these so-called coupling com pounds to react with primary aromatic amines in C the presence of oxidizing agents forms the basis Yo-on of color development in photographic subtractive i Six color processes, in which the amine developing wherein R represents a grouping of atoms nece agent becomes oxidized locally with the forma essary to complete a five-membered or six-mem tion of the silver image and immediately reacts bered heterocyclic nucleus, e. g., oxythionaph with the coupling compound to form an azo 30 thene, methyloxythionaphthene, coumaranon, methine dye image in situ with the developed sil oxyselenonaphthene, thiobarbituric acid, barbi verimage. turic acid, oxindole, homophthalimide thioox Arylaldehyde derivatives which are linked to azoledione, isohydantoin, rhodanine, selenazo gether by a single methine group and employed lonethione and the like, R1 represents an aro as filter and anti-halation dyes are already 35 matic group such as aryl, e.g., phenylnaphthyl, known. Compounds of this category are illus anthryl and the like. Said aryl group may be trated, for example, in United States Patent substituted by a radical such as an alkyl group, 2,036,546. It will be noted that the arylaldehyde e.g., methyl,ethyl, propyl, butyl, octyl, decyl, octa derivatives referred to in this patent are em decyl, stearyl, or any other, alkyl or alkylamino ployed as filter and anti-halation dyes which can 40 radical containing up to 24 carbon atoms, amino be completely and permanently decolorized with groups, e. g., primary amino, secondary amino, in a short time in photographic developing solu such as methylamino, phenylamino and the like, tions containing sodium sulfite or sodium bisulfite. or tertiary amino such as dimethylamino, di It is an object of the present invention to pro phenylamino, etc., sulfamino or solubilizing wide a new class of color-formers for the produc 45 groups such as sulfonic or carboxylic acid groups, tion of cyan and magenta, images by color-form and X represents either sulfur, oxygen, selenium, ing development. - benzo or a carbonyl radical. : A further object is to provide photographic These compounds are readily prepared by con emulsions and developer solutions which contain densing molecular proportions of an aromatic or a new class of color-formers for producing cyan cyclic aldehyde with a five-membered or six and magenta, images in situ with photographic membered heterocyclic compound containing a imageS. methylene group capable of reacting as described A still further object is to provide finished in United States Patent 2,036,546. photographs which contain stable dye images. In general, the compounds of the present in Other objects Will be apparent by reference to 55 vention are water insoluble. Their solubility in 2,449,244 3 4. water, however, is accomplished by the introduc AS examples of suitable aromatic primary lion of suitable solubilizing groups, e. g. sulfonic amino developing agents which may be employed or carboxylic acid groups into the aryl or hetero With the color coupling compound of the present cyclic nuclei of the above general formula. invention, there may be mentioned p-phenylene The compounds of the present invention when diamine, mono ethyl-p-phenylene diamine, di imployed as color-formers may ba added to the ethyl-O-phenylene diamine, 4,4'-diamino-di developer, providing they are not fast, to dif phenylamine, p-amino-dialkyl anilines, e. g., fusion in gelatin. Or to the silver-halide emul p-amino-dimethyl aniline and p-amino-di Sion in the form of a solution or a suspension in ethyl aniline. These compounds are prefer a suitable solvent. Such as 1 N-alcoholic sodium 10 ably used in the form of their salts such as or potassium hydroxide, acetone, ethyl alcohol, the hydrochloride or sulfate, since they are more isopropyl alcohol. etc. Dispersing agents. Such as Soluble and stable than the free base. The isopropylnaphthalene sulfonic acid or any of the p-amino-phenols and their substitution products dispersing agents disclosed in United States may also be used where the amino group is un Patent 2,186,717 may be used in preparing the 15 substituted. All of these compounds are char Suspension of the Water insoll be color-formers acterized by the presence of a primary amino for incorporation into developers or silver-halide group in the phenyl nucleus which enables its emulsions. Instead of gelatin the color-formers oxidation product in the developer to couple with may be incorporated in other colioidal materials, the color-forming compound to form a dye image Such as, organic esters of cellulose, super-poly 20 in the emulsion adjacent to the individual par amides, polyesters or synthetic resins. The emul ticles of the silver image. The silver image may sion may be carried by a transparent medium be removed by bleaching in the Well-known man such as cellulose esters, super-polyamides. Syn ner to leave the color image in the gelatin layer. thetic resins or a non-transparent refiecting The following example is illustrative of a suit medium such as paper, or an opaque cellulose 25 able color developing solution to which the color ester. The emulsion may be coated as a single formers may be added either as such or in the layer on the Support, or superposed layers con form of a Solution in a suitable solvent, such as taining the couplers may be coated on one or ethyl alcohol, 0.1. Nealcoholic potassium hydrox both sides of the support. The superposed layers ide, acetone and the like, or they may be dissolved may be differentially sensitized for the formation 30 in dilute sodium carbonate, sodium or potassium of a color image in the well-known manner. hydroxide solution, etc., and, added to the de When incorporating the color-formers into veloper prior to color development: photographic silver-halide emulsions, it is essen tial that the substitution of the aryl or the five p-Amino-diethylaniline HCl -----grams. 2.0 membered or six-membered heterocyclic nucleus 35 Sodium earbonate (anhydrous)---do---- 50.0 in the above general formula be such that it will Potassium bromide----------------do---- 0.2 prevent the color-formers from migrating from Water to make---------------------liter- 1. One layer to another, otherwise color distortion From the above example, it will be seen that will result upon color-forming development. the developing solution does not contain sodium Several methods have been proposed to prevent 40 Sulfite. The presence of this compound is not migration of color-formers from silver-halide necessary, Since azomethine dye formation takes emulsion layers by rendering such color-formers place in its absence during color-forming -de “fast to diffusion in gelatin.' This result may velopment. However, in order to retard the de be accomplished in several ways, as for example, veloping solution from deterioration by absorp. by substituting the aryl, or the five-membered or 45 tion of oxygen from the atmosphere, a quantity six-membered heterocyclic nucleus with suitable ranging from 2 to 5 grams may be added as a groups which impart substantive characteristics preservative, - to the color-formers which combine permanently During the course of the color-forming develop With the gelatin and other colloidal materials of ment, the reaction between the arylaldehyde de the silver-halide emulsion, or by enlarging the 50 rivative and an oxidized primary amine develop substituent group of the color-former with a long ing agent, the arylaldehyde derivative splits at chain alkyl radical so that, the color-formaer is the methine chain and is replaced by the nitro incapable of diffusing from the gelatin or other gen of the oxidized aromatic primary amine.