Peter Bergthaller

A New Method for the Synthesis of Two-Equivalent Couplers in Colour Photography

Abstract Suitable sulfanes prepared from photographic colour couplers of the 1-naphthol, pyrazolo[5,1-c](1,2,4)triazole and 3-anilinopyrazol-5-one classes have been transformed into heteroatom-substituted transient sulfur(IV) species capable of arylating a triazolate or carboxylate ligand or an added 1H-triazole via ligand exchange and a subsequent process closely related to ligand coupling. This new reaction may be named Sulfurane Contraction and there is evidence for thiophilic control of the key steps involved. The syntheses are carried out preferably at about 0°C and provide access to photographic two-equivalent colour couplers which are inaccessible by known methods.

Organic Sulfur Compounds in Silver Halide Photography

Abstract The diversity of functions of organic sulfur compounds in the most important fields of silver halide photography is reviewed. While organic sulfur compounds of the lower oxidation states (−2 to 0) are discussed mainly as important ligands for silver ions in all stages of the photographic process, those of the higher oxidation states (+2 to +4) are shown to be useful for modifying the reactivity and physical properties of auxiliary and supplementary components.