Se° oxidation

I lu se oxide aic easily decomposed. With water, ethylene oxide loi ins glycol with hydrochloi ic acid, the chloihydrin with hydio-i, mi(. K id, the cyanhydi in. Epichloihydi in behaves similarly. 

Purification of industrial oils, kerosene/jet fuel, lubricating oils Mono- dicumyldiphenylamine Mono- dioctyldiphenylamine Dimer fatty acids Purification of xylenes Improvement of bromine number of recycle cumene in phenol plants Improvement of bromine number of recycle ethylbenzene in styrene plants based on liquid pha.se oxidation Alkylation of xylenes with diisobutylenes to mono-/ rr-butyI derivatives Phenyl xylyl ethane... 

Another mode of antioxidant activity of ebselen is the suppression of peroxynitrite formation. Ebselen rapidly reacts with peroxynitrite to form ebselen Se-oxide [332]. Ebselen Se-oxide is reduced by glutathione [333] therefore, ebselen can be regenerated under in vivo conditions by redox cycling (Figure 29.20). 

El hierro puede protegerse de la corrosidn mediante la aplicacidn de una cubierta de otro metal o de pintura, que alslen al hierro del aire y el agua o anadiendo una pieza de metal ( nodo sacrificatorio) que se oxide con m s facilidad que el hierro. 

Due to its 4s24p4 electron configuration, selenium, like sulfur, forms many divalent compounds with two covalent bonds and two lone pairs, and d hybridization is quite common, to form compounds with Se oxidation states of 4+ and 6+. 

Figure 8.4. Cation exchange HPLC-ICP-MS analysis of 77Se-enriched yeast using two enzymatic sample preparation strategies (a) sequential use of /3-glucosidase and a protease mixture (b) protease XIV and (c) mass balance of selenium and selenium species fractionated during the sample preparation and HPLC separation procedure. SeMet = selenomethionine SeOMet = selenomethionine Se-oxide. Reproduced from [133] by permission of The Royal Society of Chemistry.

In contrast to Mo(OSiRR 2)(bdt)2 complexes, [Mo(OR )(S2C2R2)21 (R = Ph, Ad, or -Pr R = Me or Ph) complexes react readily with N-, S-, and Se-oxides (Fig. 14) and a detailed kinetic investigation of these OAT reactions has been accomplished (84, 85). Equation (6) summarizes the overall reaction sequence and the first step has been shown to proceed by direct OAT,... 

The [W(OR )(S2C2R2)2r (R = Ph, 2-Ad, -Pr, or p-C6H4X, where X = CN, Br, Me, OMe, or NH2 R = Me or Ph) complexes react with an N-, P-, As-, S-, or Se- oxide (QO) to form the corresponding [WO(OR )(S2C2R2)2] complex (85). As for the reactions described above, the direct nature of the OAT reaction has been demonstrated by the transfer of lsO to the W center from Ph2Se180. These reactions are second order and involve a large negative entropy of activation (Table III), indicative of an associative transition state. The relative rates of the reactions vary with the substrate as ... 

Table 21 The Numbers of Known Compounds MnXj-nL for the N, P, As, S and Se Oxide Ligands...

The dehydrogenation of steroidal and other ketones can be accomplished with (43) at elevated temperatures. Similar reactions with lactones and lactams have also been reported. Other interesting oxidations include the angular hydroxylation of ketones and the oxidation of benzylic hydrocarbons, as shown in Scheme 14. In some cases, the selenium reagent may be employed catalytically in the presence of a less expensive cooxidant that reoxidizes Se by-products back to the required Se oxidation state. 

The mechanism of these reactions leading to retention is SE(oxidative), whereas an Se(2)... 

The opposite process of Se oxidation can occur in soils (Dowdle and Oremland, 1998 Losi and Frankenberger, 1998). It is possible that Se oxidation is similar to S oxidation and may be mediated by heterotrophs and autotrophs (Losi and Frankenberger, 1998). In aerobic soil slurries, Se + was the main product, with lower amounts of Se " " being produced as a result of the activities of eterotrophic and autotrophic thiobacilli (Dowdle and Oremland, 1998). 

A batch of Se-labeled and enriched yeast was characterized with regard to isotopic composition and content of selenium species for later use in a human absorption study based on the method of enriched stable isotopes. SeMet constituted 53% of the total Se content in the yeast. Oxidation of SeMet to selenomethionine-Se-oxide (SeOMet) occurred during sample preparation... 

Benzocondensed systems like (59) have been described formed by the reaction of 5HJH-dibenzo[(>, ]-l,5-diselenocine Se-oxide with silyl triflate <92JCS(Pl)2247>. 

I.r. and radioactive tracer studies have shown that Se and Sb trace impurities in AsCl, are in the form of SeOCl2 and SbCls, respectively. The literature concerning the stereochemical behaviour of Se oxides, fluorides, and oxy-fluorides has been surveyed.Several other elements, including l e were also dealt with. 

---