Organoselenides

Selenium. Selenium is determined by atomic absorption after the organoselenides are broken down with acidic persulfate and all forms of selenium have been converted to H2Se. The reduction is brought about in acidic solution of KI—SnCl2 or borohydride, and H2Se is generated by addition... 

Ojima-Holton method 670 olefin insertion 569 (+)-ophiobolin C 716 f. organoselenides 397 ortlio-quinodimethane 155 f.,... 

Since only catalytic quantities of selenium dioxide are required, the danger of handling large quantities of this material (Note 1) is avoided. Furthermore, the problems associated with the formation of selenium and organoselenides, which commonly arise in oxidations using molar quantities of selenium dioxide, are not encountered. 

Oxidation of thiols and related compounds with organoselenium(IV) and organotellurium(rV) compounds 102 Other oxidations with selenoxides and telluroxides 106 Thiolperoxidase and haloperoxidase-like activity of organoselenides and organotellurides 108... 

Fig. 19 Representative examples of organoselenides and tellurides in the +2 and +4 oxidation states with an odd number of ligands to selenium or tellurium.

THIOLPEROXIDASE AND HALOPEROXIDASE-LIKE ACTIVITY OF ORGANOSELENIDES AND ORG ANOTET. 1.1 JRIDF..S... 

Figure 9.26. Se NMR spectra of CdSe molecular clusters isolated by encapsulation with covalently-bonded Se-phenyl or Se-butyl moieties. The Se spectra relate to the internal portion of the cluster rather than to the organoselenide ligand. Note the change in relative proportions of the three-line fitted components, shifting towards the position of the bulk material with increasing cluster size. From Thayer et at. (1988), by permission of the copyright owner.

The cleavage of diselenides to generate organoselenide ions, which are useful for the preparation of unsymmetrical selenides through alkylation, is readily achieved with Sm-MejSiCl-Hp. ... 

Se NMR spectroscopy has been considered a suitable method for tracing selenium metabolites or the fate of organoselenides in a hydrobromic acid -bromine digestion system. In particular, selena analogues of the amino acids... 

Selenium is a chalkophilic chemical trace element. It belongs to group VI of Mendeleev s periodic table, sub-group of oxygen and is similar to sulfur by its chemical properties (Figure 1). Chemical species include the seleneous and selenic acids, selenides, selenites and organoselenides. 

Organoselenide-catalyzed oxidative chlorination reactions included halolactonization, a-chlorination of ketones, and aUyhc chlorination. The ability of selenium to undergo reversible 2e oxidation-reduction chemistry facilitates halogenation through selenium-bound halogen intermediates. ... 

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