Selenium dioxide
Description
Selenium dioxide (CAS 7446-08-4), also known as selenious anhydride, is an inorganic oxidizing agent used primarily as a catalyst and reagent in chemical synthesis and industrial refining.
SeO2 enables selective oxidation reactions that are difficult to achieve with conventional oxidants, making it a targeted choice for specialty chemical production and advanced manufacturing.
In organic synthesis, it is the reagent of choice for allylic and benzylic oxidations, converting methylene groups to carbonyl compounds in pharmaceutical and fine chemical intermediates.
The electronics industry relies on it as a component in glass and ceramic formulations where controlled selenium incorporation modifies optical and electrical properties for high-tech use.
In metallurgy and mining, it functions as a refining agent for copper and other non-ferrous metals, removing impurities during electrorefining processes to ensure high metal purity.
It also serves as a precursor in the production of other selenium compounds used across pigment and catalyst manufacturing, supporting a wide range of industrial chemical applications.
The product is supplied as a white crystalline powder. Technical and reagent grades are the standard market offerings, with purity levels typically ranging from 99% upward for use.
Packaging is available in small quantities for research use through to bulk quantities for industrial procurement, with handling requirements reflecting its oxidizing classification.
Physical Properties
| Melting Point | 340 °C |
| Boiling Point | 684.9 °C(lit.) |
| Density | 3.954 g/cm³ @ Temp: 15 °C |
| Flash Point | 315°C |
| Appearance | Selenium dioxide is white to slightly reddish crystalline solid or yellow liquid which forms a yellowgreen vapor. It has a sour and pungent odor. Odor threshold in air50.0002 milligram per cubic meter. |
| Color | white |
| Form | powder |
| Water Solubility | 38.4 g/100 mL (14 ºC) |
| Vapor Pressure | 1 mm Hg ( 157 °C) |
| Refractive Index | nD20 <1.76 |
| pH | 2 (10g/l, H2O, 20℃) |
Safety & Handling (Learn More)
Trade & Regulatory
| HS Code | 28112900 |
| UN Number | 3440 |
| ADR Class | 6.1 |
| Packing Group | III |
| Storage Class | 6.1C - Combustible acute toxic Cat.3 toxic compounds or compounds which causing chronic effects |
| WGK (Germany) | 2 |
Documentation
Other Names
Selenous anhydride|Selenium(IV) oxide|Selenious anhydride|Selenium oxide (SeO2)|Selenium dioxide dimer|Selenous acid anhydride|Selenium(IV) dioxide (1:2)|Selenium oxide (Se2O4)|SeO2
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