Reactions of Some Heterocyclic Thioamides with Silver Halides in Aqueous Media

The reactions of five heterocyclic thioamides with aqueous dispersions of silver chloride, silver bromide and silver iodide have been investigated. The formation of sparingly soluble silver-thioamide compounds by the replacement of halide ions by thioamide anions plays an important role in these processes. However, physical interactions between the precipitated compound and unionized thioamide also influences the course of these reactions, especially in the case of phenyl-thioamide derivatives. Some evidence has been obtained which suggests that the photo-sensitivity of silver halide crystals is significantly reduced by the formation of a surface layer of silver-thioamide compound.