Nomenclature
CAS number: 7446-08-4
Selenium dioxide; selenious anhydride.
O
2Se; mol wt 110.96.
O 28.84%, Se 71.16%.
SeO
2.
Description and references
Prepd by burning selenium in oxygen: Berzelius, Acad. Handl. Stockholm 39, 13
(1818); Ann. Chim. Phys. [2] 9, 160, 225, 337 (1818); by burning selenium in oxygen
and nitrogen dioxide: Lenher, J. Am. Chem.
Soc. 20, 559 (1898); by oxidizing selenium
with nitric acid: A. P. Julien, ibid. 47, 1799 (1925). Toxicology: E. A. Cerwenka, W. C.
Cooper, Arch. Environ. Health 3, 189 (1961). Review: Waitkins, Clark, Chem. Rev. 36, 235-289 (1945).
Properties
Lustrous, tetragonal needles. Acidic taste; leaves
a burning sensation. Its yellowish green vapor has a pungent, sour
smell. mp 340°; d1515 3.954. Vapor pressure (mm Hg): 12.5 at 70°; 20.2 at 94°; 39.0 at
181°; 760.0 at 315°; 848.0 at 320°. nD20 <1.76. Soly (parts/100 parts solvent) in water: 38.4 (14°); in methanol:
10.16 (11.8°); in 93% ethanol: 6.67 (14°); in acetone: 4.35 (15.3°);
in acetic acid: 1.11 (13.9°). Sol in concd H2SO4. Stable to light and heat. Rapidly absorbs dry hydrogen fluoride,
hydrogen chloride, hydrogen bromide, and hydrogen iodide to form the
corresponding selenium oxyhalide. Reacts with ammonia to form nitrogen
and selenium; in alcohol soln forms ammonium ethyl selenite, HN4(C2H5)SeO3. Yields nitrogen
and black amorphous selenium with hydrazine; nitrogen and reddish-brown
amorphous selenium with hydroxylamine hydrochloride. Forms selenic
acid with nitric acid. Reduced by carbon and other organic substances.Caution
Direct contact may cause intense
local irritation of skin and eyes (Cerwenka, Cooper).Use
In the manuf of other selenium compounds; as a reagent
for alkaloids; as oxidizing agent: L. F. Fieser, M. Fieser,
Reagents for Organic Chemistry vol.
1 (New York, Wiley, 1967) p 992.