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Organoselenium chemistry is the science exploring the properties and reactivity of organoselenium compounds, chemical compounds containing carbon-to-selenium chemical bonds. [1] [2] [3] Selenium belongs with oxygen and sulfur to the group 16 elements or chalcogens, and similarities in chemistry are to be expected. Organoselenium compounds are ...
Selenium dichloride is an important reagent in the preparation of selenium compounds (e.g. the preparation of Se 7). It is prepared by treating selenium with sulfuryl chloride (SO 2 Cl 2 ). [ 10 ] Selenium reacts with fluorine to form selenium hexafluoride :
Selenium forms several allotropes that interconvert with temperature changes, depending somewhat on the rate of temperature change. When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder. When rapidly melted, it forms the black, vitreous form, usually sold commercially as beads. [14]
Polyselenides are prone to decomposition on exposure to air, in which case they are oxidized back to elemental selenium. Se 2− n + 2 H + + 1 ⁄ 2 O 2 → n Se + H 2 O. As ligands in coordination complexs, polyselenides are generally bidentate. Complexes of penta-, tetra-, and triselenide ligands are known. One example is the spirocyclic [Zn ...
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.
Its high reactivity would cause damage to cells. [19] Instead, cells store selenium in the less reactive oxidized form, selenocystine, or in methylated form, selenomethionine. Selenocysteine synthesis occurs on a specialized tRNA , which also functions to incorporate it into nascent polypeptides.
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 ...
Selenous acid is easily formed upon the addition of selenium dioxide to water. As a crystalline solid, the compound can be seen as pyramidal molecules that are interconnected with hydrogen bonds. In solution it is a diprotic acid: [ 3 ]