Chromium(III) bromide
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| Names | |
|---|---|
| IUPAC name
Chromium(III) bromide | |
| Other names
Chromium tribromide, Chromium bromide, Chromic bromide | |
| Identifiers | |
| 10031-25-1 13478-06-3 (hexahydrate) | |
| 3D model (Jmol) | Interactive image |
| ChemSpider | 74280 |
| ECHA InfoCard | 100.030.068 |
| EC Number | 233-088-6 |
| PubChem | 82309 |
| UNII | WZB719DDER  |
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| Properties | |
| CrBr3 | |
| Molar mass | 291.71 g/mol |
| Appearance | Black lustrous crystals; green in transmitted light, reddish in reflected light[1] |
| Density | 4.25 g/cm3[2] |
| Melting point | 1,130 °C (2,070 °F; 1,400 K) (anhydrous)[2] 79 °C (hexahydrate) |
| insoluble in cold water, soluble with addition of Chromium(II) ion salts,[1] soluble in hot water[2] | |
| Structure | |
| trigonal | |
| Hazards | |
| US health exposure limits (NIOSH): | |
| PEL (Permissible) |
TWA 1 mg/m3[3] |
| REL (Recommended) |
TWA 0.5 mg/m3[3] |
| IDLH (Immediate danger) |
250 mg/m3[3] |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Chromium(III) bromide is an inorganic compound with the chemical formula CrBr3. It is a dark colored solid that appears green in transmitted light but red with reflected light. It is used as a precursor to catalysts for the oligomerization of ethylene.
Synthesis
The compound is prepared in a tube furnace by the reaction of bromine vapor and chromium powder at 1000 °C. It is purified by extracting with absolute diethyl ether to remove any CrBr2, and is subsequently washed with absolute diethyl ether and absolute ethanol.[1]
Analogous to the behavior of related chromium(III) halides, the tribromide dissolves in water to give CrBr3(H2O)3 only upon the addition of catalytic amounts of a reducing agent, which generates CrBr2.[1] The reducing agent generates chromous bromide on the surface of the solid, which dissolves and re-doxidizes to Cr(III).
References
- 1 2 3 4 Brauer, Georg (1965) [1962]. Handbuch Der Präparativen Anorganischen Chemie [Handbook of Preparative Inorganic Chemistry] (in German). 2. Stuttgart; New York, New York: Ferdinand Enke Verlag; Academic Press, Inc. p. 1340. ISBN 978-0-32316129-9. Retrieved 2014-01-10.
- 1 2 3 Perry, Dale L. (2011). Handbook of Inorganic Compounds, Second Edition. Boca Raton, Florida: CRC Press. p. 122. ISBN 978-1-43981462-8. Retrieved 2014-01-10.
- 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0141". National Institute for Occupational Safety and Health (NIOSH).