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Following rearrangement and loss of water, a second equivalent of water attacks the alpha position. Red amorphous selenium is liberated in the final step to give the 1,2-dicarbonyl product. [8] [9]: 4331 Allylic oxidation using selenium-dioxide proceeds via an ene reaction at the electrophilic selenium center.
Selenium is a chemical element; it has the symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in Earth's crust.
A selenocyanate is an ion or chemical compound that contains the -SeCN group, which could be in the form of an anion, SeCN −. Organic selenocyanates also exist. Some complex ions with transition metals such as silver and mercury (mercuriselenocyanates) are known. Mercuriselenocyanate salts also include K, Fe, Co, Ni, Cu, Zn, and Cd. [1]
Form, link and image elements could be referenced with a hierarchical name that began with the root document object. A hierarchical name could make use of either the names or the sequential index of the traversed elements. For example, a form input element could be accessed as either document.myForm.myInput or document.forms[0].elements[0].
Selected reaction monitoring (SRM), also called multiple reaction monitoring (MRM), is a method used in tandem mass spectrometry in which an ion of a particular mass is selected in the first stage of a tandem mass spectrometer and an ion product of a fragmentation reaction of the precursor ions is selected in the second mass spectrometer stage ...
In organic chemistry, the Wurtz reaction, named after Charles Adolphe Wurtz, is a coupling reaction in which two alkyl halides are treated with sodium metal to form a higher alkane. 2 R−X + 2 Na → R−R + 2 NaX. The reaction is of little value except for intramolecular versions, such as 1,6-dibromohexane + 2 Na → cyclohexane + 2 NaBr.
In molecular biology a selenoprotein is any protein that includes a selenocysteine (Sec, U, Se-Cys) amino acid residue. Among functionally characterized selenoproteins are five glutathione peroxidases (GPX) and three thioredoxin reductases, (TrxR/TXNRD) which both contain only one Sec. [1] Selenoprotein P is the most common selenoprotein found in the plasma.
Xenon does not react with oxygen directly; the trioxide is formed by the hydrolysis of XeF 6: [115] XeF 6 + 3 H 2 O → XeO 3 + 6 HF. XeO 3 is weakly acidic, dissolving in alkali to form unstable xenate salts containing the HXeO − 4 anion. These unstable salts easily disproportionate into xenon gas and perxenate salts, containing the XeO 4− ...