Photographic element, compound, and process

#This invention relates to a silver halide photographic element containing a phenolic cyan dye-forming coupler bearing a substituted carbonamido group in the 2-position and a carbonamido group in the 5-position containing a sulfonyl group.

#In silver halide based color photography, a typical photographic element contains multiple layers of light-sensitive photographic silver halide emulsions coated on a support with one or more of these layers being spectrally sensitized to each of blue light, green light and red light. The blue, green, and red light-sensitive layers typically contain yellow, magenta, and cyan dye-forming couplers, respectively. After exposure to light, color development is accomplished by immersing the exposed material in an aqueous alkali solution containing an aromatic primary amine color-developing agent. The dye-forming couplers are selected so as to react with the oxidized color developing agent to provide yellow, magenta and cyan dyes in the so called subtractive color process to reproduce their complementary colors, blue, green and red as in the original image.

#The important features for selecting the dye-forming coupler include, efficient reaction with oxidized color developing agent, thus minimizing the necessary amounts of coupler and silver halide in the photographic element; the formation of dyes with hues appropriate for the photographic use of interest, for color photographic paper applications this requires that dyes have low unwanted side absorption leading to good color reproduction in the photographic print; minimization of image dye loss contributing to improved image permanence under both ambient illumination and conventional storage conditions; and in addition the selected dye-forming coupler must exhibit good solubility in coupler solvents, provide good dispersibility in gelatin and remain stable during handling and manipulation for maximum efficiency in manufacturing processes.

#The following is an example of how couplers useful in the invention may be synthesized.

#6-Amino-5-Chloro-2-methylbenzoxazole (1)

#Concentrated sulfuric acid (150 mL) was stirred mechanically and cooled in an ice/water bath. To this was gradually added 5-chloro-2-methylbenzoxazole, (75 g, 0.45 Moles), at such a rate that the temperature stayed at 30° C., over a 15-20 minute period. A solution of concentrated sulfuric acid (40 mL), and concentrated nitric acid (32 mL), was prepared and added drop by drop to the benzoxazole solution at such a rate that the temperature was maintained at approximately 20° C. When this acid solution had been added the cooling bath was removed and the mixture allowed to stir at room temperature for 1 hour. At the end of this period the solution was carefully poured onto ice with good stirring. Sufficient water was then added to get good mixing. The solid was filtered off, washed well with water followed by methanol and finally air dried. Yield 5-chloro-2-methyl-6-nitrobenzoxazole, 90.6 g.