Color photographic element containing a fragmentable electron donor for improved photographic response

This invention comprises a multicolor photographic element comprising a support bearing a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, wherein at least one of said layers comprises large tabular grains having an average circular diameter of greater than 2 mum and contains a fragmentable electron donating compound is of the formula: X-Y' or a compound which contains a moiety of the formula -X-Y'; whereinX is an electron donor moiety, Y' is a leaving proton H or a leaving group Y, with the proviso that if Y' is a proton, a base, beta-, is covalently linked directly or indirectly to X, and wherein:1) X-Y' has an oxidation potential between 0 and about 1.4 V; and2) the oxidized form of X-Y' undergoes a bond cleavage reaction to give the radical X. and the leaving fragment Y'; and, optionally,3) the radical X. has an oxidation potential