Seleninic acid

Gould has reported the following acidity constants (in H20 at 25 °C) for some substituted benzene seleninic acids ArSe 02H. 

Optically active arenetellurinic acid 23 was obtained for the first time by chromatographic resolution of the racemic sample on a chiral column in 2004.37 It is stable toward racemization in solution, whereas the corresponding seleninic acids racemize in solution under similar conditions. Its absolute configuration was assigned by comparing the circular dichroism spectra with that of an optically active seleninic acid (Scheme 10). 

Kinetic studies on racemization, oxygen exchange reaction using H2lsO, and theoretical studies clarified the mechanism for racemization of optically active chalcogenic acids.34,37 The mechanism of racemization of tellurinic acids is different from that of the corresponding seleninic acids. In fact, the mechanism for racemization of optically active tellurinic acids was found to involve an... 

Diorgano diselenides have been used extensively as precursors to seleninic acids in the presence of hydrogen peroxide.The catalytic activity of preformed seleninic acids and seleninic acids generated in situ are identical. Diorgano ditellurides have also been used as catalysts in thiolperoxidase-like reactions for the oxidation of thiols with various peroxides. However, tellurinic acids are not thought to be involved even though RTe(=0)SPh types of structures are proposed as intermediates. 

Abstract—The results of solving the Schrodinger equation for the simple case of a proton moving in a potential field with two equal minima are given for a series of physically possible parameters. Several examples of infrared spectra containing double voh bands such as potassium hydrogen phosphate, carboxylic acids, and seleninic acid, are discussed wad compared with the results of the calculations. 

Iodine in the presence of sodium hydrogen carbonate converts diselenides quantitatively into seleninic acids ... 

Dibenzyl diselenide crystallises from alcohol in yellow needles, which are slightly deeper in colour than those of the p-nitrobenzyl compound, and melt at 92° to 93° C. Exposure to light for an hour or so causes the crystals to turn red. The selenide readily dissolves in hot alcohol, but is only sparingly soluble in ether, insoluble in water. Oxidation with fuming nitric acid converts it into benzyl seleninic acid, and boiling with copper or mercury in suspension precipitates selenium. Boiling with iodine in chloroform solution gives the tetra-iodide, M.pt. 98° C. the tetrabromide melts at 137° C.5... 

Bromophenyl-p-seleninic acid, C6H4Br.Se02H, is obtained by oxidising p-bromophenylselenoglycollic acid in acetic acid solution with hydrogen peroxide. It crystallises from hot water in colourless needles, decomposing at 187° C., and giving a reddish-purple coloration with concentrated sulphuric acid. 

Methyl-j8-naphthylselenone, C10H7.SeO2.CH3, occurs when the sodium salt of naphthalene-j8-seleninic acid in methyl alcohol is boiled with methyl iodide for a long period. After treatment with water and extraction with ether, removal of the latter and crystallisation from alcohol gives a 48 per cent, yield as golden-yellow crystals, M.pt. 136° C. The selenone may also be obtained by the oxidation of methyl-j3-naphthyl selenide with permanganate. 

It has already been pointed out that this compound may be prepared by hydrolysis of the selenocyanate it may also be obtained by the interaction of sodium selenide and 1-chloroanthraquinone. By the latter process orange-red plates, M.pt. 212° C., result. If 2-chloroanthra-quinone be used in the reaction, 2-anihraquinone selenophenol is obtained as an orange-yellow product, which gives a violet-red solution in sulphuric acid. Concentrated nitric acid causes oxidation to the seleninic acid. 

In an unusual modified chromone synthesis, enaminones formally derived from o-hydroxyacetophenone react with selenium oxychloride prior to cyclisation resulting in the formation of Se-bridged bischromones. Various reactions at Se are described, including fission of an Se-Se bond, leading to chromone-3-seleninic acid (95JHC43). 

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