Patent GB-504376-A (GB)
Title: Improvements in the production of colour photographic pictures
IPC: G03C7/36
Filed: 1937-08-24
Abstract: 504,376. Colour photography. GROVES, W. W. (I. G: Farbenindustrie Akt.-Ges.) Aug. 24, 1937, No. 23190. [Class 98 (ii)] [Also in Group IV] In the production of colour photographic pictures by colour development, the exposed silver halide emulsion is developed with a colour developer in the presence of a colour coupler consisting of a pyridine derivative of the general formula wherein h is an organic radical such as an alkyl, aryl, or aralkyl radical, and X is an inorganic acid residue such as C1, Br, or I, and wherein the pyridine ring may contain substituents or may be fused on to another ring. The colour coupler may be in a silver halide emulsion, and may be in one or more layers of a multilayer material, and may contain a group which hinders its diffusion from the emulsion. The colour-coupler may alternatively be in the developer. Colour couplers obtained by the reaction of a pyridine compound such as pyridine, picoline, 3-aminopyridine, and dipyridine, with an alpha-halogenketone such as w-chloracetophenone, w-bromacetophenone, monochloracetone, symmetrical dichloracetone, w-bromoalpha- or #-acetonaphthone, p-phenyl-w-bromacetophenone, p-phenylw-chloracetophenone, and diphenylene-p, p<1>- dichloromethyl ketone are referred to. On development with a p-dialkylaminoaniline developer, yellow dyestuff pictures are produced. The colour couplers may be made fast to diffusion by the introduction of groups as described in Specifications 458,400, 465,823, 479,838, 483,000, 484,698, 489,093, 489,274, 491,958, and 491,959. The groups may be present in the ketone, or may be introduced into the pyridine nucleus or into any other position in the molecule. They may be linked with the nucleus directly or through an amino, hydroxyl, or carboxyl group in the form of the acid anide or an ester. Single or multilayer materials with the layers on the same or opposite sides of the support may contain the colour couplers, or a mixture of emulsion particles containing different colour couplers may be applied to a support. The material may be developed by ordinary colour development or by reversal development as described in Specifications 468,946 and 481,501. A developing composition includes p-dimethylaminoaniline and phenacylpicolinium chloride. After removal of the developed silver a yellow picture is obtained. P-phenylphenacylpyridinium chloride may be added to a gelatine silver halide emulsion, and the exposed emulsion may be developed with p-dimethylaminoaniline to give a yellow picture. The pyridine derivatives of the general formula referred to above are obtained by reacting an alpha-halogen ketone with a pyridine derivative containing a tertiary nitrogen atom. Pyridine compounds referred to are pyridine, picoline, 3-aminopyridine, and dipyridine. alpha-Halogen ketones referred to are w-chloracetophenone, w-bromacetophenone, monochloracetophenone, symmetrical dichloracetone, w-bromo-alpha-or #- acetonaphthone, p-phenyl-w-bromacetophenone p-phenyl-w-chloracetophenone, and diphenylene p-p<1>-dichloromethyl ketone. The reaction may proceed in the absence of a solvent, or in the presence of a solvent such as benzene or ether. Chlorates, sulphates, and the like may be prepared from the halogen derivatives by double decomposition. In examples : (a) phenacylpicolinium chloride is prepared by heating a mixture of d-picoline and w-chloracetophenone for several hours at 120 C., and (b) p-phenylphenacylpyridinium chloride is prepared by heating a mixture of pyridine and p-phenyl-w-chloracetophenone at 120 C. until the mixture solidifies. The Provisional Specification describes also a developing composition including p-dimethylaminoaniline and phenacyl-2-hydroxy-3-nitro-5-chloropyridinium chloride giving a yellow picture.