Selenides oxidation potentials

The oxidation potentials of diphenyl selenides ° and diphenyl tellurides have been measured by electrochemical methods, as well as by pulse radiolysis. Pulse electrolysis was used to determine E° values for diphenylsulfide (84), diphenylselenide (85), and diphenyltelluride (23). In each case, equilibrium... 

For comparison within the chalcogens, the oxidation potentials of the Ph-E-Me series 94, 95b, 96b, and 97b, where E = O, S, Se, Te, respectively, were evaluated by pulse radiolysis.Consistent with the analogous diaryl series, the values for this series indicate that the compounds are increasingly easy to oxidize, with telluride 97b most easily oxidized (0.74 V) and ether 94 least easily oxidized (1.62 V), with these values vs. NHE (Table 10). Eor a broader comparison, series of four or five para-substituted arylmethylsulfides, selenides, and tellurides, 95a-e, 96a-e, and 97a-d were prepared and their values determined in the same manner (Table 10). The same trends were observed, with the thioethers least... 

Table 12 Oxidation potentials of alkyl phenyl selenides...

Table 15 Oxidation potentials and peak potentials of selenides and diselenides...

As a second example of chemical properties we have considered peak oxidation potentials of 4,4 -disubstituted diphenyl selenides and diphenyl tellurides. We consider these quantities to be chemical properties because no covalent bonds have been formed or broken. The best regression equations obtained were for the selenides ... 

The differences between the oxidation potentials of like forms of selenium and sulfur probably account for the separation of selenium and sulfur in the weathering cycle (Table III). Hydrogen selenide is readily oxidized to elemental selenium. Selenium dioxide is easily reduced to... 

The oxidation potentials of various fluoroalkyi sulfides, selenides, and tellurides have been determined by use of cyclic voltammetry. These substances exhibit irreversible multiple anodic waves. In Table 5 is summarized the first oxidation peak potentials ( p) of these substances together with those of some nonfluorinated and other electronegatively substituted chalcogeno compounds. In all cases, the fluorinated compounds are oxidized at more positive potentials than the corresponding nonfluorinated compounds because of the electron-withdrawing effects of fluoroalkyi groups. It should be noted... 

Because the redox potential of selenides is sufficiently low, oxidative generation of Se-Se and S-Se dications on treatment with sulfuric acid is more general than in the case of disulfonium dications. For example, formation of dications 106 and 108 occurs readily when the corresponding bis-selenide 105 and... 

More recent research has focused on the binary Ru sulfides and selenides. Schulenberg et al. showed that modifying a Ru/C with Se (via H2Se03) improved activity by a factor of three. It was concluded that the Se inhibited surface oxide formation that limits active sites with Ru/C. Both catalysts showed some H2O2 formation at lower potentials (e.g., 3% at... 

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