Arsenic tribromide
{{chembox
| Watchedfields = changed
| verifiedrevid = 443401000
| ImageFile = Arsenic-tribromide-3D-balls.png
| ImageSize =
| ImageName = Ball and stick model of arsenic tribromide
| PIN = Arsenic tribromide
| SystematicName = Tribromoarsane
| OtherNames = Arsenic(III) bromide
Arsenous bromide, Arsenicum Bromatum, Tribromoarsine
|Section1={{Chembox Identifiers
| InChI1 = 1/AsBr3/c2-1(3)4
| InChIKey1 = JMBNQWNFNACVCB-UHFFFAOYAH
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 7784-33-0
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 41CN475O7F
| PubChem = 24569
| ChemSpiderID = 22973
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| EINECS = 232-057-4
| RTECS = CG1375000
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/AsBr3/c2-1(3)4
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = JMBNQWNFNACVCB-UHFFFAOYSA-N
| SMILES = Br[As](Br)Br
| InChI = 1S/AsBr3/c2-1(3)4
| InChIKey = JMBNQWNFNACVCB-UHFFFAOYSA-N}}
|Section2={{Chembox Properties
| Formula = {{chem2|AsBr3}}
| MolarMass = 314.634 g/mol
| Appearance = white to pale yellow crystalline solid
| Density = 3.54 g/cm3
| Solubility = soluble, partial hydrolysis indicated by fumes
| MeltingPtC = 31.1
| MeltingPt_notes =
| BoilingPtC = 221
| BoilingPt_notes =
| RefractIndex = 2.3
| MagSus = −106.0·10−6 cm3/mol
}}
|Section3={{Chembox Hazards
| IDLH = Ca [5 mg/m3 (as As)]{{PGCH|0038}}
| REL = Ca C 0.002 mg/m3 [15-minute]
| PEL = [1910.1018] TWA 0.010 mg/m3
}}
|Section8={{Chembox Related
| OtherCompounds = Phosphorus tribromide
arsenic trichloride
}}
}}
Arsenic tribromide is an inorganic compound with the formula {{chem2|As Br3}}, it is a bromide of arsenic. Arsenic is a chemical element that has the symbol As and atomic number 33. This pyramidal molecule is the only known binary arsenic bromide. {{chem2|AsBr3}} is noteworthy for its very high refractive index of approximately 2.3. It also has a very high diamagnetic susceptibility.CRC handbook of Chemistry and Physics, CRC Press 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:
{{chem2|2 As2O3 + 3 S + 6 Br2 → 4 AsBr3 + 3 SO2}}
Arsenic tribromide is a highly water soluble crystalline arsenic source for uses compatible with bromides and lower (acidic) pH. Most metal bromide compounds are water soluble for uses in water treatment, chemical analysis and in ultra high purity for certain crystal growth applications. Arsenic bromide is generally immediately available in most volumes."Arsenic Tribromide" in Handbook of Preparative Inorganic Chemistry, 2nd ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 597.
It is soluble in hydrocarbons; carbon tetrachloride; very soluble in ether, benzene, chlorinated hydrocarbons, carbon disulfide, oils, and fats.{{cn|date=January 2025}}
Bromides of arsenic
{{chem2|AsBr5}} is not known, although the corresponding phosphorus compound {{chem2|PBr5}} is well characterized. {{chem2|AsBr3}} is the parent for a series of hypervalent anionic bromoarsenates including {{chem2|[As2Br8](2-)}}, {{chem2|[As2Br9](3-)}}, and {{chem2|[As3Br12](3-)}}.Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.
Organoarsenic bromides {{chem2|(CH3)2AsBr}} and {{chem2|(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.{{cn|date=January 2025}}
Safety
Arsenic tribromide is highly toxic. It is a carcinogen and a teratogen.{{cn|date=January 2025}}