Organo-selenium compounds

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

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. 

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. 

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)... 

The bio-availabilities of these elements through the gastrointestinal tract vary markedly. Molybdenum, iodine, fluorine, and arsenic are apparently highly bio-available, whereas medium uptake occurs with haem iron, cobalt, zinc, chromium in the presence of a glucose tolerance factor, selenium, either as selenate or as organo selenium compounds, whereas only low bio-availability is experienced with non-haem iron,... 

Speciation of the many inorganic and organo-selenium compounds is performed by various coupling techniques based on liquid and gas chromatography combined with the major detection methods (e.g.,... 

The initial interest in selenium in medicine was caused by its potential toxicity, although the discovery of selenium as an essential element in human metabolism influenced explosively the need of selenium determinations in biological materials. In the determination of selenium in human materials it is necessary to take the various naturally occurring chemical forms of Se into consideration. When administered to humans or animals, the organic forms of the element are readily converted to various organo-selenium compounds. The available information suggest that the behaviour of selenium in man is quite similar to that in rats and other animals (Bopp et al.. 1982)... 

A modification of the method described in Clesceri et al. (1998) was used to quantify the concentrations of selenite (Se(lV)) in the samples. An aliquot of the filtered sample was reacted with sodium borohydride to distill off any Se(lV) as selenium hydride. The concentration of selenium remaining in solution after the reaction was measured. The difference between original concentration (total dissolved) Se and residual Se in solution is taken as the value for Se(IV). Because of the high concentrations of organo-selenium compounds in the samples, attempts to separate Se(VI) and Se(IV) in the sample by this method (see Clesceri et al., 1998) were not successful. 

A wide variety of microorganisms (including those common in wastewater treatment systems) and fungi have the ability to convert SeO , SeOf , Se(0), and various organo-selenium compounds into the volatile form (Doran and Alexander, 1977 Cook and Bruland, 1987 ... 

Ebselen (2-phenyl-l,2-benzisoselenazol-3(2H)-one) is an organo-selenium compound that functions as an anti-oxidant it can directly scavenge hydrogen peroxide and peroxynitrite, mimics GSH peroxidase, and acts as an anti-inflammatory agent (Schewe, 1995). Ebselen itself reduced HN2-mediated inflammation at 24 h in the MEVM when applied in three treatments after exposure, with the first starting at 15 min. Although several ebselen derivatives are in development and have shown efficacy... 

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