Selenides Selenium dioxide

Contact with elemental selenium does not injure the skin. Selenium dioxide, however, upon contact with water, sweat, or tears, forms selenous acid, a severe skin irritant. Selenium oxyhaHdes are extremely vesicant and cause bums when in contact with human skin (91,92). Hydrogen selenide affects the mucous membranes of the upper respiratory tract and the eyes (93). 

The method described here is a modification of that of Schoeller.1 Diphenyl selenide has also been prepared from diazotized aniline and alkali monoselenides 2 by the Friedel-Crafts reaction with benzene and selenium tetrachloride3 or selenium dioxide 4 from diphenyl sulfone and selenium 5 from phenylmagnesium bromide and selenium,6 selenium dichloride,7... 

Compounds Selenium dioxide selenium trioxide selenium oxychloride sodium selenite sodium selenate hydrogen selenide selenic acid selenium sulfide selenium disulfide... 

The oxidation of 2-butene with selenium dioxide in acetic acid solution produces l-acetoxy-2-butene as the oxidation product of the olefin and bis(l-methyl-2-acetoxypropyl)-selenide (I) as the final reduced state of the oxidant instead of elemental selenium. Further, (I) may act as a catalyst for the oxidation of 2-butene with peracetic acid or oxygen to 3-acetoxy-1-butene. A mechanism is proposed to explain the formation of selenides in the oxidation of olefins with selenium dioxide and their catalytic activity in the oxidation of olefins with other oxidants. 

Purification of the Organoselenium Compounds. After the oxidation of 2-butene with selenium dioxide was completed, the acetic acid solvent and the volatile reaction products were distilled at reduced pressure (10 mm. HgA). The residue, a yellow oil, was purified by adsorption chromatography in a column packed with silica gel. n-Hexane and ethyl ether were used as eluents. The same procedure was applied to the fractionation and purification of the organoselenium compounds obtained from the oxidation of bis(l-methyl-2-acetoxypropyl) selenide with peracetic acid. 

Oxidation of 2-Butene with Selenium Dioxide. The stoichiometry of the reaction of 2-butene with selenium dioxide shows that approximately 0.85 mole of l-acetoxy-2-butene plus 0.85 mole of bis(l-methyl-2-acetoxypropyl) selenide are produced per mole of selenium dioxide consumed. This suggests that, at least for this particular group of olefins, in the mechanism of olefin oxidation with selenium dioxide the formation of selenides should be considered as the final reduced state of the oxidant rather than elemental selenium. 

When passed over heated iron boride, the gas interacts, forming iron selenide and selenium boride.7 With water no stable compound is produced, although the existence of an unstable crystalline hydrate has been observed.8 Sulphur dioxide and selenium dioxide oxidise a solution of hydrogen selenide, the product in the latter case being red selenium 9... 

Hydrogen selenide irritates the nose, eyes, and lung tissue, and disturbs the digestive and nervous systems. Solutions of selenium compounds may burn the skin and cause severe pain by skin absorption. Selenium dioxide dust irritates the respiratory system, eyes, and... 

Selenium is generally reduced during cellular metabolism (76) Therefore, selenate would yield selenite, followed by a further reduction to selenide (77, 79) Greeder and Milner (67) and Milner and Hsu (74) have reported little difference exists in the efficacy of sodium selenite, sodium selenate and selenium dioxide to inhibit tumor proliferation. 

Iron diselenide, FeSe2, is prepared by heating anhydrous ferric chloride to dull red heat in hydrogen selenide.3 When ignited in oxygen, it yields ferric oxide and selenium dioxide. 

Toxicity and health effects Selenium causes hair and nail loss, discoloration and decay of the teeth, and CNS disturbances, including pain and anesthesia of the extremities. Inhalation of hydrogen selenide causes pulmonary edema. The dusts of selenium produce respiratory tract irritation, while the fumes of selenium dioxide produce metal fume fever. Dermal exposure and ingestion of selenium oxychloride cause skin burns, corrosive injury to the gastrointestinal tract, stupor, respiratory depression, and refractory hypotension. Ingestion of selenious acid causes corrosive injury to the gastrointestinal tract, stupor, respiratory depression, and refractory hypotension... 

The oxidation of linalyl acetate with selenium dioxide in methanol affords, in addition to the usual allylic oxidation products, two cyclic selenides 1 and 284. 

A rough estimate of (C - Se) may be obtained from the heat of combustion of diethyl selenide, measured by Merten and Schliiter to be 749 7 0 7 kcal, the selenium-containing product being selenium dioxide. Estimating the heat of vaporization, we obtain (G -Se)/ 50 kcal. 

Heating diaryl ditellurium compounds in pyridine with selenium dioxide or diselenium dichloride led to the insertion of a selenium atom into the Te — Te bond and the oxidation of one or more of the chalcogen atoms in the bis[aryltelluro] selenides. ... 

It also combines with a number of metals to form compounds called selenides. An example is magnesium selenide (MgSe). One of selenium s interesting properties is its reaction with oxygen. It burns in oxygen with a bright blue flame to form selenium dioxide (Se02). Selenium dioxide has a characteristic odor of rotten horseradish. 

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