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| Names | |
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Preferred IUPAC name
Arsenic tribromide | |
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Systematic IUPAC name
Tribromoarsane | |
| Other names
Arsenic(III) bromide
Arsenous bromide | |
| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.029.143 |
| EC Number |
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PubChem CID
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| UNII | |
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CompTox Dashboard (EPA)
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| Properties | |
| AsBr3 | |
| Molar mass | 314.634 g/mol |
| Appearance | white to pale yellow crystalline solid |
| Density | 3.54 g/cm3 |
| Melting point | 31.1 °C (88.0 °F; 304.2 K) |
| Boiling point | 221 °C (430 °F; 494 K) |
| soluble, partial hydrolysis indicated by fumes | |
| -106.0·10−6 cm3/mol | |
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Refractive index (nD)
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2.3 |
| Hazards | |
| NIOSH (US health exposure limits): | |
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PEL (Permissible)
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[1910.1018] TWA 0.010 mg/m3 |
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REL (Recommended)
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Ca C 0.002 mg/m3 [15-minute] |
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IDLH (Immediate danger)
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Ca [5 mg/m3 (as As)] |
| Related compounds | |
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Related compounds
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Phosphorus tribromide arsenic trichloride |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Arsenic tribromide is the inorganic compound with the formula AsBr3. This pyramidal molecule is the only known binary arsenic bromide. AsBr3 is noteworthy for its very high refractive index of approximately 2.3. It also has a very high diamagnetic susceptibility. The compound exists as colourless deliquescent crystals that fume in moist air.
Preparation
Arsenic tribromide can be prepared by the direct bromination of arsenic powder. Alternatively, arsenic(III) oxide can be used as the precursor in the presence of elemental sulfur:
- 2 As2O3 + 3 S + 6 Br2 → 4 AsBr3 + 3 SO2
Bromides of arsenic
AsBr5 is not known, although the corresponding phosphorus compound PBr5 is well characterized. AsBr3 is the parent for a series of hypervalent anionic bromoarsenates including [As2Br8]2−, [As2Br9]3−, and [As3Br12]3−.
Organoarsenic bromides, (CH3)2AsBr and (CH3)AsBr2 are formed efficiently by the copper-catalyzed reaction of methyl bromide with hot arsenic metal. This synthesis is similar to the direct process used for the synthesis of methyl chlorosilanes.
Safety
Arsenic tribromide is toxic, as are most arsenic compounds.