Polarographic behaviour of mercaptopyrimidines

Oxidation process induced by 2-mercaptopyrimidine at a mercury electrode

“…Note that Reaction (2) involves one electron per 2MP molecule, which means that the results in Ref. [9] are also compatible with the occurrence of Reaction (2) under dc polarographic conditions. Furthermore, cathodic stripping voltammetry at the hanging mercury drop electrode (HMDE) was used in the analytical determination of 2MP, on the basis of Reactions (1) and/or (2) [11].…”

“…Its limiting current is proportional to the concentration of 2MP, and its half-wave potential depends on this variable, changing in +0.11 V when the 2MP concentration increases from 4 × 10 −5 to 4 × 10 −4 M. It is also apparent that, at low concentrations, the wave extends over a wide range of potentials. Based on the previous reports [9,13], this wave results in the formation of an HgSR or an Hg(SR) 2 species according to Reaction (1) or (2), respectively.…”

“…[8]. ) A few electrochemical investigations concerning 2MP have been published previously [9][10][11][12][13]. With one sole exception [13], they were performed in aqueous solutions with polarographic or voltammetric techniques, and show that 2MP is involved in an oxidation and a reduction process at mercury and silver electrodes.…”

“…From the value of the limiting current and the pH dependence of the half-wave potential of the main wave, it was established that one electron and (at pH lower than pK for the equilibrium in Scheme 1) one proton per 2MP molecule are involved in the overall oxidation reaction. On this basis-and because 2MP was considered to be a thiol compound-Izquierdo et al [9] proposed the reaction Nevertheless, a complex of the type Hg(SR) 2 was obtained by bulk electrolysis using an acetonitrile solution of 2MP and a sacrificial anode of mercury, according to Reaction (2) [13]:…”

“…In Ref. [9], the electrooxidation process at mercury was studied using a dropping mercury electrode in connection with dc polarography. It was found that 2MP gives a main anodic wave, which is accompanied by a prewave "small noticeably" at more negative potentials.…”