PURPOSE: To speed up development and to sharpen an image by reacting a specified compd. with a 4-equiv. magenta coupler, and introducing a thioether group into the active site of said coupler in one step to obtain a 2-equiv. coupler.
CONSTITUTION: A sulfur contg. compd. represented by formula I or II is reacted at normal temp. with the active site of a 4-equiv. magenta coupler to obtain a thioether type 2-equiv. magenta coupler of formula III. In formula I WIII, R, R2, R5 are each alkyl, alkenyl, aryl, or the like; R1, R3, R4 are each H, alkyl, alkenyl, or the like, or a cation; and Coup is a magenta coupler residue free of H at the coupling active site. The 2-equiv. coupler thus obtained is better in coupling reactivity than the 4-equiv. coupler, and more suitable for rapid color development. An amt, of silver halide to be used is halved because of the 2- equiv. coupler, reduced in cost, thinned in an emulsion layer, and further, improved in resolution of a color image and its sharpness.
NINOMIYA HIDETAKA
MASUDA KOUSAKU
