Abstract

An electrochemical study related to the electrooxidation of the 3-hydroxyl and 3-methyl derivatives of 1-phenyl-4-butyldithio-carboxylate-5-hydroxypyrazol in aqueous ethanolic solutions covering a wide pH interval has been performed. In this study, these compounds are considered as potential collector agents for copper mineral sulfide flotation. From the potentiodynamic parameters for both compounds in solution, as well as for the 3-methyl derivative adsorbed on a glassy carbon electrode surface, it was established that these compounds undergo a dimerization process involving the formation of the respective bisthiocarbonyl disulfide derivative. On the basis of the voltammetric and coulometric data, as well as from the analysis of the product obtained after a preparative electrolysis carried out with the 3-methyl derivative, a mechanism accounting for the nature of the reaction product in aqueous ethanolic solutions is proposed. (C) 2000 Elsevier Science B.V. All rights reserved.