2-(4-ETHILTHIOPHENYL) PYRROLE AS A REAGENT FOR PALLADIUM DETERMINATION

Abstract

The purpose of this research was to develop a selective rapid method for verifying the presence of palladium. For the first time, 2-(4-ethilthiophenyl) pyrrole has been used as a reagent for palladium determination. The reagent was obtained by the Trofimov reaction from 4-ethylthiophenylketoxime and acetylene at atmospheric pressure (Potassium Hydroxide/Dimethyl Sulfoxide, 96 °С, 5 h). It is established that Pd (II) and 2-(4-ethilthiophenyl) pyrrole form a complex compound of yellow colour in hydrochloric solutions (6 M of HCl, with a pH of up to 5). This compound absorbs in the visible region, λ = 415 nm. The properties of the palladium pyrrole complex were studied by an extraction-photometric method. The limits of Pd (II) concentrations (0,5-5,0 μg/ml), obeying the basic law of photometry, were revealed. The developed method for verifying the presence of Pd has been tested on complex solutions and the samples of industrial catalyst RC-404. It is shown that the new reagent provides a high selectivity of Pd (II) determination in the presence of Ag (I), Mn (II), Zn (II), Pb (II) and Ni (II), Al (III), Fe (III), Bi (III), Th (IV), Pt (IV), (VI), W (VI) and (VI), with the accuracy of analysis being ± 4%. In comparison with other analytical reagents, 2-(4-ethylthiophenyl) pyrrole is characterized by a high accuracy and good reproducibility of results, as well as by the selectivity and promptness of the analysis (4-5 min).