Hydrazide redox-dye-releasing compounds for photothermographic elements

A photothermographic element comprising a support bearing at least one heat-developable, photosensitive, image-forming photothermographic emulsion layer comprising:

• (a) a photosensitive silver halide;
• (b) a non-photosensitive, reducible source of silver;
• (c) a reducing agent for the non-photosensitive, reducible silver source;
• and
• (d) a binder;
• wherein the reducing agent comprises a hydrazide redox-dye-releasing compound of the general formulae:
• ##STR10## wherein:
• D represents a chromophore of a thermally mobile dye;
• X represents a divalent linking group;
• n.gtoreq.1;
• and R.sup.1 and R.sup.2 are each independently selected from the group consisting of a ballasting group;
• an alkyl or alkenyl group of up to 20 carbon atoms;
• an alkoxy group of up to 20 carbon atoms;
• an aryl group of up to 20 carbon atoms;
• an alkaryl group of up to 20 carbon atoms;
• an aralkyl group of up to 20 carbon atoms;
• an aryloxy group of up to 20 carbon atoms;
• a non-aromatic heterocyclic ring group containing up to 6 ring atoms;
• an aromatic heterocyclic ring group containing up to 6 ring atoms;
• an alicyclic ring group comprising up to 6 ring carbon atoms;
• a fused ring group comprising up to 14 ring atoms;
• and a bridging group comprising up to 14 ring atoms.

A method of producing an image comprising:

• (a) imagewise exposing an element comprising a support bearing at least one heat-developable, photosensitive, image-forming photothermographic emulsion layer comprising:
• (i) a photosensitive silver halide;
• (ii) a non-photosensitive, reducible source of silver;
• (iii) a reducing agent for the non-photosensitive, reducible silver source;
• and
• (iv) a binder;
• wherein the reducing agent compound comprises a hydrazide redox-dye-releasing compound of the formulae:
• R.sup.1 --[--C(O)--NH--NH--SO.sub.2 --X--D].sub.n or [D--X--C(O)--NH--NH--SO.sub.2 --].sub.n --R.sup.2
• wherein:
• D represents a chromophore of a thermally mobile dye;
• X represents a single bond or a divalent linking group;
• R.sup.1 or R.sup.2 independently represent an organic group;
• and n.gtoreq.1, and
• (b) developing the element to form an image.