Selenium trioxide

Structural formula
General
Surname	Selenium trioxide
other names	Selenium (VI) oxide Selenic anhydride
Molecular formula	SeO 3
Brief description	colorless solid
External identifiers / databases
CAS number 13768-86-0 EC number 237-385-1 ECHA InfoCard 100,033,972 PubChem 115128 Wikidata Q6070
properties
Molar mass	126.958 g mol −1
Physical state	firmly
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Selenium trioxide is an inorganic chemical compound of selenium from the group of oxides .

Extraction and presentation

Selenium trioxide can be obtained by reacting potassium selenate with sulfur trioxide .

${\displaystyle \mathrm {K_{2}SeO_{4}} +(n+1)\;\mathrm {SO_{3}} \longrightarrow \mathrm {K_{2}SO_{4}} \cdot n\;\mathrm {SO_{3}} +\mathrm {SeO_{3}} }$

properties

Selenium trioxide is a colorless solid that reacts with water under intense heating to form selenic acid. It dissolves in acetic anhydride and liquid sulfur dioxide . It does not have a defined boiling point, but begins to sublime slowly under normal pressure from around 100 ° C and decomposes from 180 ° C. The oxidative power of the compound is so strong that alcohol is already ignited at −80 ° C. It consists of eight-membered ring molecules Se ₄ O ₁₂ . In the gas phase, this tetramer is in equilibrium with monomeric selenium trioxide.

use

Selenium trioxide is suitable for the gentle selenonation of hydrocarbons . Fluoroselenic acid can be produced by reacting with hydrofluoric acid .

${\displaystyle {\ce {SeO3 + HF -> HSeO3F}}}$

Individual evidence

1. ↑ ^{a b c d} Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 422.
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ↑ Ralf Steudel : Chemistry of Non-Metals: From Structure and Bond to Application . Walter de Gruyter, 2008, ISBN 3-11-021128-9 , p. 461 ( limited preview in Google Book search).
4. ↑ Max Schmidt, Irmgard Wilhelm: Solutions of Selentrioxid. In: Chemical Reports. 97, 1964, pp. 872-875, doi : 10.1002 / cber.19640970334 .
5. ↑ Jane E. Macintyre: Dictionary of Inorganic Compounds . CRC Press, 1992, ISBN 0-412-30120-2 , pp. 3128 .