Tellurium behavioral effect

In contrast to the cathodic reduction of organic tellurium compounds, few studies on their anodic oxidation have been performed. No paper has reported on the electrolytic reactions of fluorinated tellurides up to date, which is probably due to the difficulty of the preparation of the partially fluorinated tellurides as starting material. Quite recently, Fuchigami et al. have investigated the anodic behavior of 2,2,2-trifluoroethyl and difluoroethyl phenyl tellurides (8 and 9) [54]. The telluride 8 does not undergo an anodic a-substitution, which is totally different to the eases of the corresponding sulfide and selenide. Even in the presence of fluoride ions, the anodic methoxylation does not take place at all. Instead, a selective difluorination occurs at the tellurium atom effectively to provide the hypervalent tellurium derivative in good yield as shown in Scheme 6.12. 

The similar behavior of CO and CHO in reactions 0 + C2H and O + C2H provided confirmation to the conclusion that the same CH2 radical is formed by the primary steps of these reactions. In an earlier work4 (using discharge in H20 vapor involving less 02 molecules in the reaction vessel), the formation of CH2 in a reaction of O atoms with C2H4 was evident from its effect on a tellurium mirror. The reaction yielding... 

Test of Uptake Model Based on a Slow Surface Reaction Combined with Diffusion within the Particle. Since the simple diffusion model is inadequate to describe the uptake behavior of the molybdenum and tellurium oxide vapors by the clay loam particles, a more complex model is required, in which the effects of a slow surface reaction and of diffusion of the condensed vapor into the particle are combined. Consider the condensation of a vapor at the surface of a substrate (of any geometry) and the passage by diffusion of the condensed vapor through a thin surface layer into the body of the substrate. The change in concentration of solute per unit volume in the surface layer caused by vapor condensa-... 

Where the condensation coefficient of the vapor is quite small, as for molybdenum and tellurium oxides condensing on the clay loam particles, the initial rate seems to be determined by the combined effect of a slow reaction and slow diffusion of the condensed vapor into the substrate. An equation has been derived which relates the amount of vapor uptake to the condensation coefficient of the vapor onto the substrate material, the equilibrium uptake of the vapor by the substrate material, and the diffusion constant of the condensed vapor in the substrate material. This equation has yet to be tested extensively in other systems, but it does describe successfully the uptake behavior of molybdenum oxide vapor by the clay loam particles. 

---