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Identifiers | |
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3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.029.246 |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
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Molar mass | 184.113 g/mol (anhydrous) 292.204 g/mol (hexahydrate) |
Appearance | white hygroscopic hexagonal crystals (anhydrous) colorless monoclinic crystals (hexahydrate) |
Density | 3.72 g/cm3 (anhydrous) 2.07 g/cm3 (hexahydrate) |
Melting point | 711 °C (1,312 °F; 984 K) 172.4 °C, decomposes (hexahydrate) |
Boiling point | 1,250 °C (2,280 °F; 1,520 K) |
102 g/(100 mL) (anhydrous) 316 g/(100 mL) (0 °C, hexahydrate) | |
Solubility | ethanol: 6.9 g/(100 mL) methanol: 21.8 g/(100 mL) |
−72.0·10−6 cm3/mol | |
Structure | |
Rhombohedral, hP3 | |
P-3m1, No. 164 | |
octahedral | |
Thermochemistry | |
Heat capacity (C) | 70 J/(mol·K) |
Std molar entropy (S⦵298) | 117.2 J/(mol·K) |
Std enthalpy of formation (ΔfH⦵298) | −524.3 kJ/mol |
Hazards | |
NFPA 704 (fire diamond) | |
Safety data sheet (SDS) | External SDS |
Related compounds | |
Other anions | |
Other cations | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Magnesium bromide are inorganic compounds with the chemical formula MgBr2(H2O)x, where x can range from 0 to 9. They are all white deliquescent solids. Some magnesium bromides have been found naturally as rare minerals such as: bischofite and carnallite. [2] [3]
Magnesium bromide can be synthesized by treating magnesium oxide (and related basic salts) with hydrobromic acid. [3] It can also be made by reacting magnesium carbonate and hydrobromic acids, and collecting the solid left after evaporation. [2]
As suggested by its easy conversion to various hydrates, anhydrous MgBr2 is a Lewis acid. In the coordination polymer with the formula MgBr2(dioxane)2, Mg2+ adopts an octahedral geometry. [4]
Magnesium bromide is used as a Lewis acid catalyst in some organic synthesis, e.g., in aldol reaction. [5]
Magnesium bromide also has been used as a tranquilizer [2] and as an anticonvulsant for treatment of nervous disorders. [6]
Magnesium bromide modifies the catalytic properties of palladium on charcoal. [7]
Magnesium bromide hexahydrate has properties as a flame retardant. [8]
Treatment of magnesium bromide with chlorine gives magnesium chloride. This reaction is employed in the production of magnesium chloride from brines. [9]
Two hydrates are known, the hexahydrate and the nonahydrate. Several reports claim a decahydrate, but X-ray crystallography confirmed that it is a nonahydrate. The hydrates feature [Mg(H2O)6]2+ ions.<ref>Hennings, Erik; Schmidt, Horst; Voigt, Wolfgang (2013). "Crystal Structures of Hydrates of Simple Inorganic Salts. I. Water-Rich Magnesium Halide Hydrates MgCl2·8H2O, MgCl2·12H2O, MgBr2·6H2O, MgBr2·9H2O, MgI2·8H2O and MgI2·9H2O". Acta Crystallographica Section C Crystal Structure Communications. 69 (11): 1292–1300. doi:10.1107/S0108270113028138. PMID 24192174.</ref it can also cause violently convulsing and potential release of bowels