Diselenides, catalytic hydrogenation

Diorgano diselenides have been used extensively as precursors to seleninic acids in the presence of hydrogen peroxide.The catalytic activity of preformed seleninic acids and seleninic acids generated in situ are identical. Diorgano ditellurides have also been used as catalysts in thiolperoxidase-like reactions for the oxidation of thiols with various peroxides. However, tellurinic acids are not thought to be involved even though RTe(=0)SPh types of structures are proposed as intermediates. 

The catalysts applied to alkene epoxidation in fluorinated alcohol solvents can be subdivided into those which are metal/chalconide-based and those which are purely organic in nature (Scheme 4.5). The former comprise arsanes/arsane oxides [27,28], arsonic acids [29, 30], seleninic acids/diselenides ]31-35], and rhenium compounds such as Re207 and MTO (methylrhenium trioxide) ]36,37]. As shown in Scheme 4.5, their catalytic activity is ascribed to the intermediate formation of, for example, perseleninic/perarsonic adds or bisperoxorhenium complexes. In other words, their catalytic effect is due to the equilibrium transformation of hydrogen peroxide to kmetically more active peroxidic spedes. 

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