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Whereas SO 2 tends to be molecular and SeO 2 is a one-dimensional chain, TeO 2 is a cross-linked polymer. [5] SeO 2 is considered an acidic oxide: it dissolves in water to form selenous acid. [6] Often the terms selenous acid and selenium dioxide are used interchangeably. It reacts with base to form selenite salts containing the SeO 2− 3 anion.
Selenium forms two oxides: selenium dioxide (SeO 2) and selenium trioxide (SeO 3). Selenium dioxide is formed by the reaction of elemental selenium with oxygen: [5] + It is a polymeric solid that forms monomeric SeO 2 molecules in the gas phase. It dissolves in water to form selenous acid, H 2 SeO 3.
Selenium oxide may refer to either of the following compounds: Selenium dioxide, SeO 2; Selenium trioxide, SeO 3; Diselenium pentoxide, Se 2 O 5
Selenium trioxide is produced in the laboratory by the reaction of anhydrous potassium selenate (K 2 SeO 4) and sulfur trioxide (SO 3). [25] Salts of selenous acid are called selenites. These include silver selenite (Ag 2 SeO 3) and sodium selenite (Na 2 SeO 3). Hydrogen sulfide reacts with aqueous selenous acid to produce selenium disulfide:
Oxidations involving selenium dioxide are often carried out with catalytic amounts of the selenium compound and in presence of a sacrificial catalyst or co-oxidant such as hydrogen peroxide. SeO 2-based oxidations sometimes afford carbonyl compounds such as ketones, [22] β-Pinene [23] and cyclohexanone oxidation to 1,2-cyclohexanedione. [24]
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In the decade that ensued, selenium-mediated oxidation rapidly expanded in use, and in 1939, Andre Guillemonat and co-workers disclosed the selenium dioxide-mediated oxidation of olefins at the allylic position. [2] Today, selenium-dioxide-mediated oxidation of methylene groups to alpha ketones and at the allylic position of olefins is known as ...
Meanwhile, economists at Goldman Sachs project GDP is pacing at 2.4% for the quarter. Still, Williamson noted the growth in the US economy remains heavily skewed to activity in the services sector.