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Diphenyl diselenide itself is also a source of a weakly electrophilic PhSe group in reactions with relatively powerful nucleophiles like Grignard reagents, lithium reagents and ester enolates (but not ketone enolates or weaker nucleophiles). PhSeCl is both more reactive, and more efficient, since with Ph 2 Se 2 half of the selenium is wasted.
Ketones with two available α-methylene positions react more quickly at the least hindered position.: [1] Allylic oxidation can be predicted by the substitution pattern on the olefin. In the case of 1,2-disubstituted olefins, reaction rates follow CH > CH 2 > CH 3: Geminally-substituted olefins react in the same order of reaction rates as above ...
Some selenium-containing heterocycles exhibit antiinflammatory and antitumor activity, among other medicinal uses. Using selenourea as a precursor is considered to be the most efficient means of selenium-containing heterocyclic synthesis. [9] Another class of reactions is the complexation of selenourea with transition metals and metalloids.
Selenium is found in metal sulfide ores, where it substitutes for sulfur. Commercially, selenium is produced as a byproduct in the refining of these ores. Minerals that are pure selenide or selenate compounds are rare. The chief commercial uses for selenium today are glassmaking and pigments. Selenium is a semiconductor and is used in photocells.
Selenium compounds are compounds containing the element selenium (Se). Among these compounds, selenium has various oxidation states , the most common ones being −2, +4, and +6. Selenium compounds exist in nature in the form of various minerals, such as clausthalite , guanajuatite , tiemannite , crookesite etc., and can also coexist with ...
The introduction of React Hooks with React 16.8 in February 2019 allowed developers to manage state and lifecycle behaviors within functional components, reducing the reliance on class components. This trend aligns with the broader industry movement towards functional programming and modular design.
Gpx1, Gpx2, Gpx3, and Gpx4 have been shown to be selenium-containing enzymes, whereas Gpx6 is a selenoprotein in humans with cysteine-containing homologues in rodents. Amyloid beta, when bound to heme, has been shown to have peroxidase activity. [2] A typical group of peroxidases are the haloperoxidases. This group is able to form reactive ...
Iodine supplementation in selenium-deficient populations is theoretically problematic, partly for this reason. [8] Selenocysteine (abbreviated as Sec or U, in older publications also as Se-Cys) [80] is the 21st proteinogenic amino acid, and is the root of iodide ion toxicity when there is a simultaneous insufficiency of biologically available ...