The following are summaries of four of the papers presented a t a Meeting of the Analytical Division, in conjunction with the Thermal Methods Group and the Historical Group of the CS, held on October 24th, 1979, at the Scientific Societies Lecture Theatre, Savile Row, London.
The reactions between silver@) ions and rhodanine and a number of related heterocyclic compounds have been investigated by simple electrometric methods, which have enabled the nature of these reactions to be elucidated. A comparison of the behaviour of suitably substituted compounds towards silver(1) ions has enabled us to ascertain the function of each group in the rhodanine molecule with respect to silver, and to establish an analyticofunctional group for silver. A suggested structure that accords with the known composition and properties of silver rhodanide is given. RHODANINE and some similar heterocyclic compounds precipitate silver(1) ions from aqueous solution. The reaction is generally assumed to involve the replacement of the acidic irnino-hydrogen by the silver ion. However, the precise analytico-functional group responsible for the highly selective action of these compounds, and the structures of the resulting complexes are not known, although Feigl has shown that there must be a C=S group adjacent to the imino-group for these sparingly soluble silver complexes to form. The formation of apparently similar silver complexes by 3-substituted rhodanines, which have no imino-hydrogen, seems to contradict previous hypotheses about the mechanism of this reaction. Such theories, however, are based on mainly qualitative investigation^.^-^ The present investigation, therefore, was designed to obtain quantitative information about the reaction of silver(1) ions with rhodanine and similar compounds, so that the reaction mechanism could be elucidated with more certainty. Potentiometric techniques were used to follow the change in silver and hydrogen ion concentrations during the reactions. The only measurements made on the precipitates were those of their infrared spectra, elemental analyses having been found to be unreliable.2The heterocyclic compounds have been selected so that each differs from rhodanine in only one part of the molecule; the function of each part in the reaction with silver(1) ions has thus been deduced, and the analytico-functional grouping determined. It has also been possible to assign a feasible structure to silver rhodanide. F. Feigl and I. Pollak, Mikrochem., 1926, 4, 185.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.