Novel electron donor precursors and photographic element containing them

摘要

Novel electron donor precursors have the structure: wherein: Z represents the atoms to complete a mono-, bi- or tricyclic ring system, each ring of which contains 5 to 6 nuclear atoms; n is 1 or 2; R1 is a monovalent aromatic group when n is 1 and a bivalent aromatic group when n is 2; and R2 represents hydrogen, an alkyl group, an aryl group, an acyl group, an ester group or an amido group. The compounds are useful in photographic elements, film units and processes to provide electrons to immobile compounds which must accept at least one electron before releasing a diffusible dye or photographic reagent.