Organo selenium

Reaction scheme for the formation of organo-selenium compounds (X = halogen). 

Methylated organo-selenium has been determined by GC/MS or fluorine-induced chemiluminescence to determine DMSe, DMDSe, and DMSeS. This last compound, dimethyl selenenyl sulfide, was mistakenly identified as dimethyl selenone (CH3Se02CH3) in earlier work with bacteria.181,182 However, much recent work with many microorganisms have shown ample evidence of DMSeS production from Gram-negative bacteria,181,183 phototrophic bacteria,167,184 phytoplankton185 and in B. juncea detailed above. SPME with microwave-induce plasma atomic emission spectrometry was recently used to... 

Selenium dioxide is also an oxygen donor to alkenes. In this case, however, the initial reaction of the double bond is with the selenium center followed by two pericyclic steps. After hydrolysis of the organo-selenium intermediate, the result is a hydroxylation at the allylic carbon position65. Thus, limonene (2) yields racemic p-mentha-l,8(9)-dien-4-ol66. The high toxicity of selenium intermediates and prevalence of many rearrangements has limited the widespread use of the reagent in synthesis. 

It has been reported occasionally that variable quantities of organo-selenium compounds are produced during the oxidation (3, 7). These compounds have been considered as side reaction products and have received little attention regarding their nature or possible role in the reaction. In this work we have studied the characteristics of these organoselenium compounds, their role in the mechanism of the oxidation of olefins with selenium dioxide, and their catalytic properties in the oxidation of olefins with other oxidants. 

Selenium atoms in organo-fluorine compounds are oxidized to higher oxidation states by the same or similar methods to those used for organosulfur compounds. Thus, fluoroalkyl selenides 1 are oxidized to higher oxidation state compounds 2 by rer(-butyl hypochlorite under mild conditions.215... 

The interaction of selenium tetrachloride and barium diacetylacetone does not give organo-selenium derivatives. 

The present volume describes 1166 selenium, 489 tellurium, 90 chromium, and 8 platinum compounds. It is the first time that the organo-derivatives of these four elements have been collectively reviewed in detail. 

Since sulfur chemistry lies beyond the scope of this review and organo-tellurium chemistry so far has not been of any impact on organometallic chemistry in general, this section will be restricted to the discussion of redistribution equilibria on selenium. 

Dietz, C., J. S. Landaluze, P. Ximenez-Embun. 2004. SPME-multicapillary GC coupled to different detection systems and applied to volatile organo-selenium speciation in yeast. J. Anal. At. Spectrom. 19 260-266. 

Bird, S.M., Ge, H., Uden, P.C., Tyson, J.F., Block, E., and Donoyer, E. 1997a High performance liquid chromatography of selenoamino acids and organo selenium compounds. Speciation by inductively coupled plasma mass spectrometry. J. Chromatogr. 789, 349-359. 

H.J. Gysling, Organo tellurium Imaging Systems, Proc. Int. Symp. Org. Selenium Tellurium Compd., 3rd,... 

In keeping with the usual group trend, selenium and even more so tellurium show cationic behavior, which manifests itself in the formation of complexes and organo derivatives. We can deal here only with a few leading examples. 

A useful modification of selenium dioxide allylic oxidation was introduced by Sharpless in 1977. An inevitable complication of the normal reaction is the production of odoriferous low-valent selenium species which may be difficult to remove from the product mixtures and which can give rise to organo-selenium by-products. Sharpless provided a solution to this problem by the introduction into tlw re-... 

Moreno, M.E., Perez-Conde, C., Camara, C. The effect of the presence of volatile organo-selenium compounds on the determination of inorganic selenium by hydride generation. Anal. Bioanal. Chem. 375, 666-672 (2003)... 

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