Electrochemistry of aromatic diselenides and ditellurides in aprotic media. Preceding formation of mercury-containing compounds

The diorganoselenium and selenides compounds electrochemistry

The electrochemical behavior of Ar(2)SeCl(2), and Ar(2)Se(2), (Ar:CH(3)OC(6)H(5); C(2)H(5)OC(6)H(5)) in acetonitrile (AN) containing tetrabutylammonium tetrafluoroborat (TBAFB) as supporting electrolyte was studied on a stationary electrode (spe). In order to elucidate the electrode reactions linear potential scan, cyclic voltammetry and controlled-potential coulometry were employed using a platinum electrode. It is shown that Ar(2)SeCl(2) and Ar(2)Se(2) are reduced and oxidized to Ar(2)Se, Ar(2)Se(2)Ar(2), Se, and Ar(2)Se(BF(4))(2). It is generally accepted that as final electrochemical reduction products, the corresponding Ar(2)Se, Ar(4)Se(2), and Se were formed. The disappearance of the diorganoselenium and selenide in the course of the coulometric experiments was validated by measuring the limiting current of the voltammetric waves at spe and UV spectrometry.

Electrochemistry of diphenylditelluride at the hanging mercury drop electrode in a protic medium

The electrochemical behavior of diphenylditelluride, Phi2Te2, at a hanging mercury drop electrode has been studied in an aqueous-ethanol solution at pH 7 by means of cyclic and ac voltammetry. The appearance of two cathodic peaks has been attributed to the reversible reduction of the first and all the successive monolayers of a film of PhiTe-Hg, which is formed by adsorption of Phi2Te2 at the mercury/solution interface. The different electrochemical properties of such monolayers have been explained.

Synthesis, Structure, and Ligand-Based Reduction Reactivity of Trivalent Organosamarium Benzene Chalcogenolate Complexes (C5Me5)2Sm(EPh)(THF) and [(C5Me5)2Sm(μ-EPh)]2

To compare the ligand-based reduction chemistry of (EPh)(-) ligands in a metallocene environment to the sterically induced reduction chemistry of the (C(5)Me(5))(-) ligands in (C(5)Me(5))(3)Sm, (C(5)Me(5))(2)Sm(EPh) (E = S, Se, Te) complexes were synthesized and treated with substrates reduced by (C(5)Me(5))(3)Sm: cyclooctatetraene; azobenzene; phenazine. Reactions of PhEEPh with (C(5)Me(5))(2)Sm(THF)(2) and (C(5)Me(5))(2)Sm produced THF-solvated monometallic complexes, (C(5)Me(5))(2)Sm(EPh)(THF), and their unsolvated dimeric analogues, [(C(5)Me(5))(2)Sm(mu-EPh)](2), respectively. Both sets of the paramagnetic benzene chalcogenolate complexes were definitively identified by X-crystallography and form homologous series. Only the (TePh)(-) complexes show reduction reactivity and only upon heating to 65 degrees C.

Polarographic and Voltammetric Determination of Submicromolar Concentrations of Genotoxic 1,5-Dinitronaphthalene

Polarographic and voltammetric behavior of 1,5-dinitronaphthalene was investigated using tast polarography and differential pulse polarography at a classic dropping mercury electrode and differential pulse voltammetry and adsorptive stripping voltammetry at a hanging mercury drop electrode. Optimum conditions have been found for the determination of tested substance in the concentration range 2-10 μmol l-1 in tast polarography, 0.2-1 μmol l-1 in differential pulse polarography at a classic dropping mercury electrode or differential pulse voltammetry at a hanging mercury drop electrode, and 0.02-0.1 μmol l-1 using adsorptive stripping voltammetry. A possible mechanism of the electrochemical reduction of 1,5-dinitronaphthalene at mercury electrodes is discussed.

New efficient electrochemical synthesis of 1,5-dithioxylopyranosides in the presence of a sacrificial anode

Electroreduction of the disulfide derivative RSSR (5, R= [bond]C(6)H(4)[bond]CO[bond]C(6)H(4)[bond]CN) on a mercury pool or a carbon gauze electrode in the presence of 2,3,4-tri-O-acetyl-5-thio-D-xylopyranosyl bromide (1), using a sacrificial zinc anode gave an alpha,beta anomeric mixture of [4-(4-cyanobenzoylphenyl)] 2,3,4-tri-O-acetyl-1,5-dithio-D-xylopyranoside (6) in 40-70% yield, according to the experimental conditions used (nature of solvent, electrolyte salt, and temperature). High selectivity favouring the alpha anomer of 6 is observed starting from the alpha anomer of 1. Mechanistic aspects are discussed.