Selenium salt

In many reactions, selenium is an oxidant as well as a reductant. Strong oxidants convert selenium dioxide and its derivatives to the hexavalent state. Although hexavalent selenium compounds are oxidants, these are less active and difficult to reduce. Selenium salts resemble the corresponding sulfur and tellurium salts in behavior. 

Table 31.3 Toxicity of Selenium Salts to Aquatic Biota (Values shown are in pg/L [ppb] in medium fatal to 50% of the organisms during exposure for various intervals.)...

Newton, M.E and Lilly, L.J. (1986). Tissue specific clastogenic effects of chromium and selenium salts in vivo. Mutation Res. 169 61-69. 

The following triphenyl selenium salts are also known dichromate, decomposing at 238° C., erystallisable from dilute acetic acid picrate, crystallising from alcohol, M.pt. 141° to 142° C. and the nitrate, M.pt. 107° to 108° C., separating from a concentrated aqueous solution on addition of concentrated nitric acid. 

Small Quantities. Wear nitrile rubber gloves, eye protection, laboratory coat, and respirator (or work in hood). The selenium salt is dissolved in water and the solution is neutralized by the addition of 1 M NaOH (prepared by dissolving 4 g of NaOH in 100 mL of water) or 1 M sulfuric acid (prepared by cautiously adding 5 mL of concentrated acid to 85 mL of cold water). A 1 M solution of sodium sulfide (prepared by dissolving 7.8 g of Na2S in 100 mL of water) is added to the selenium salt solution and the pH is again adjusted to neutral with 1 M sulfuric acid solution. The precipitate is separated by filtration or decantation. Wash, dry, and recycle or send for disposal in a secure landfill.1 ... 

In 1942, significant new initiatives were stipulated into the standards. Samples for bacteriological examination from various points in the distribution system were to be obtained, requiring a minimum number of bacteriological samples for examination each month. The laboratories and the procedures used in making the examinations became subject to state and federal inspection at any time. Maximum permissible concentrations were also established for lead, fluoride, arsenic, and selenium. Salts of... 

Amphoteric, anionic, and nonionic surfactants are eliminated in the urine and feces. Selenium salts are excreted in the urine. Lindane has a half-life of 18-21 h following dermal application. 

Biswas S. 1997. Clastogenic effects of an inorganic selenium salt in human peripheral lymphocytes in vitro. Cell Chromosome Res 20(2) 67-72. 

Biswas S, Talukder G, Sharma A. 1997. Selenium salts and chromosome damage. Mutat Res 390 201-205. 

Franke K, Moxon AL, Poley WE, et al. 1936. Monstrosities produced by injection of selenium salt into hen s eggs. Anat Rec 65 15-22. 

Selenium and Selenium Salts, Tariff Information Series, F. L. 22. j, (1921). 

Biswas S, Talukder G and Sharma A (1999) Comparison of dastogenic effects in inorganic selenium salts in mice in vivo as related to concentrations and duration of exposure. BioMetals 12 361-368. 

Syntheses of Alkylidene cyclopropanes Via the Selenonium route The selenonium route proved to be more valuable. It has been specifically designed by us to replace the deficient selenoxide route (Scheme 38). It was expected to produce alkylidene cyclopropanes by a mechanism which mimics the selenoxide elimination step but which involves a selenonium ylide in which a carbanion has replaced the oxide. Cyclopropyl selenides are readily transformed to the corresponding selenonium salts on reaction with methyl fluorosulfonate or methyl iodide in the presence of silver tetrafluoroborate in dichloromethane at 20 °C and, as expected, methylseleno derivatives are more reactive than phenyl-seleno analogs. Alkylidene cyclopropanes are, in turn, smoothly prepared on reaction of the selenium salts at 20 °C with potassium tert-butoxide in THF (Scheme 38). Mainly alkyl cyclopropenes form at the beginning of the reaction. They then slowly rearranges, in the basic medium, to the more stable alkylidene cyclopropanes( 6 kcal/mol). In some cases the complete isomerisation requires treatment of the mixture formed in the above reaction with potassium fcrt-butoxide in THF. The reaction seems to occur via a selenonium ylide rather than via a P-elimina-tion reaction promoted by the direct attack of the /crt-butoxide anion on the P-hydrogen of the selenonium salt, since it has been shown in a separate experiment that the reaction does not occur when a diphenylselenonium salt (imable to produce the expected intermediate) is used instead of the phenyl-methyl or dimethyl selenonium analogs. It has also been found that the elimination reaction is the slow step in the process, since styrene oxide is formed if the reaction is performed in the presence of benzaldehyde which traps the ylide intermediately formed... 

Internal epoxides react only slowly and, therefore selective deoxygenation of diepoxides is possible. The reaction can be carried out as a catalytic process by addition of (C2H50>2P0Na (1-2 equiv.) to a solution of the epoxide and Te (0.1 equiv.) in C2H5OH. The selenium salt corresponding to 1 is much less reactive in this deoxygenation and is less suitable for catalytic deoxygenations. ... 

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