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Selenium is toxic in high concentrations. As sodium selenite, the chronic toxic dose for human beings was described as about 2.4 to 3 milligrams of selenium per day. [7] In 2000, the US Institute of Medicine set the adult Tolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at 400 μg/day. [8]
Representatives of selenides, diselenides, and selenols include respectively selenomethionine, diphenyldiselenide, and benzeneselenol. The sulfoxide in sulfur chemistry is represented in selenium chemistry by the selenoxides (formula RSe(O)R), which are intermediates in organic synthesis, as illustrated by the selenoxide elimination reaction.
Sodium selenate is produced by oxidation of selenium, first with nitric acid, producing selenous acid. The selenous acid is neutralized to form sodium selenite. The sodium selenite is oxidized in a basic medium hydrogen peroxide to form a selenate, which is then spray-dried. [3] Se + 2HNO 3 → H 2 SeO 3 + NO + NO 2 H 2 SeO 3 + Na 2 CO 3 → Na ...
An example is acetylcyclohexanone elimination with benzeneselenylchloride and sodium hydride. [26] Scheme 2. Selenoxide elimination of carbonyl compounds. The Grieco elimination is a similar selenoxide elimination using o-nitrophenylselenocyanate and tributylphosphine to cause the elimination of the elements of H 2 O.
Selenomethionine is readily available as a dietary supplement. It has been suggested by nutritionists that selenomethionine, as an organic form of selenium, is easier for the human body to absorb than selenite, which is an inorganic form. [8] It was determined in a clinical trial that selenomethionine is absorbed 19% better than selenite. [8]
It is a colorless, malodorous, toxic gas. It dissolves in aqueous solution, to give the hydrogenselenide or biselenide ion HSe −. At higher pH, selenide forms. Solutions of hydrogen selenide and selenide are oxidized by air to give elemental selenium: 2 SeH − + O 2 → 2 Se + 2 OH −. Most elements form selenides.
The chronic toxic dose of selenite for humans is about 2400 to 3000 micrograms of selenium per day. [141] Hydrogen selenide is an extremely toxic, corrosive gas. [ 142 ] Selenium also occurs in organic compounds, such as dimethyl selenide, selenomethionine , selenocysteine and methylselenocysteine , all of which have high bioavailability and ...
Reacts with water in an unusual or dangerous manner (e.g., caesium, sodium, diborane, sulfuric acid). SA: Simple asphyxiant gas (specifically helium, nitrogen, neon, argon, krypton, and xenon). The SA symbol shall also be used for liquified carbon dioxide vapor withdrawal systems and where large quantities of dry ice are used in confined areas. [2]