Magnesium bromide

Magnesium bromide¹
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Identifiers
CAS Number	7789-48-2 (anhydrous) Y; 13446-53-2 (hexahydrate) N; 75198-45-7 (decahydrate) N;
3D model (JSmol)	Interactive image;
ChemSpider	74219 Y;
ECHA InfoCard	100.029.246
PubChem CID	522691;
UNII	2VC6P60SLN Y;
CompTox Dashboard (EPA)	DTXSID7064865 ;
	InChI InChI=1S/2BrH.Mg/h21H;/q;;+2/p-2 Y Key: OTCKOJUMXQWKQG-UHFFFAOYSA-L Y; InChI=1/2BrH.Mg/h21H;/q;;+2/p-2 Key: OTCKOJUMXQWKQG-NUQVWONBAY;
	SMILES [Mg+2].[Br-].[Br-];
Properties
Chemical formula	MgBr2 (anhydrous); MgBr2·6H2O (hexahydrate);
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)
Solubility in water	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)
Magnetic susceptibility (χ)	−72.0·10−6 cm3/mol
Structure
Crystal structure	Rhombohedral, hP3
Space group	P-3m1, No. 164
Coordination geometry	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)	source ↗ 1 0 0
Safety data sheet (SDS)	External SDS
Related compounds
Other anions	Magnesium fluoride; Magnesium chloride; Magnesium iodide;
Other cations	Beryllium bromide; Calcium bromide; Strontium bromide; Barium bromide; Radium bromide;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

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.²³

Synthesis

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

Uses and reactions

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 tranquilizer² 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

Structure

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.¹⁰

References

Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. pp. 4–67. ISBN 0-8493-0594-2.
Gruyter, W. Concise Encyclopedia Chemistry, Walter de Gruyter & Company: Berlin, 1993; 612
Lewis, R.J. Hawley’s Condensed Chemical Dictionary, 15th ed.; John Wiley & Sons Inc.:New York, 2007; 777
Fischer, Reinald; Görls, Helmar; Meisinger, Philippe R.; Suxdorf, Regina; Westerhausen, Matthias (2019). "Structure–Solubility Relationship of 1,4-Dioxane Complexes of Di(hydrocarbyl)magnesium". Chemistry – A European Journal. 25 (55): 12830–12841. doi:10.1002/chem.201903120. PMC 7027550. PMID 31328293.
Evans, David A.; Tedrow, Jason S.; Shaw, Jared T.; Downey, C. Wade (2002). "Diastereoselective Magnesium Halide-Catalyzed anti-Aldol Reactions of Chiral N-Acyloxazolidinones". Journal of the American Chemical Society. 124 (3): 392–393. doi:10.1021/ja0119548. PMID 11792206.
Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
Bouzide, Abderrahim (2002). "Magnesium Bromide Mediated Highly Diastereoselective Heterogeneous Hydrogenation of Olefins". Organic Letters. 4 (8): 1347–50. doi:10.1021/ol020032m. PMID 11950359.
Mostashari, S. M.; Fayyaz, F. (2008). "XRD characterization of the ashes from a burned cellulosic fabric impregnated with magnesium bromide hexahydrate as flame-retardant". Journal of Thermal Analysis and Calorimetry. 92 (3): 845. doi:10.1007/s10973-007-8928-4. S2CID 94416902.
Seeger, Margarete; Otto, Walter; Flick, Wilhelm; Bickelhaupt, Friedrich; Akkerman, Otto S. (2000). "Magnesium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a15_595. ISBN 3-527-30673-0.
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.

[hand-1] Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. pp. 4–67. ISBN 0-8493-0594-2.

[ReferenceA-2] Gruyter, W. Concise Encyclopedia Chemistry, Walter de Gruyter & Company: Berlin, 1993; 612

[l-3] Lewis, R.J. Hawley’s Condensed Chemical Dictionary, 15th ed.; John Wiley & Sons Inc.:New York, 2007; 777

[4] Fischer, Reinald; Görls, Helmar; Meisinger, Philippe R.; Suxdorf, Regina; Westerhausen, Matthias (2019). "Structure–Solubility Relationship of 1,4-Dioxane Complexes of Di(hydrocarbyl)magnesium". Chemistry – A European Journal. 25 (55): 12830–12841. doi:10.1002/chem.201903120. PMC 7027550. PMID 31328293.

[5] Evans, David A.; Tedrow, Jason S.; Shaw, Jared T.; Downey, C. Wade (2002). "Diastereoselective Magnesium Halide-Catalyzed anti-Aldol Reactions of Chiral N-Acyloxazolidinones". Journal of the American Chemical Society. 124 (3): 392–393. doi:10.1021/ja0119548. PMID 11792206.

[6] Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8

[7] Bouzide, Abderrahim (2002). "Magnesium Bromide Mediated Highly Diastereoselective Heterogeneous Hydrogenation of Olefins". Organic Letters. 4 (8): 1347–50. doi:10.1021/ol020032m. PMID 11950359.

[8] Mostashari, S. M.; Fayyaz, F. (2008). "XRD characterization of the ashes from a burned cellulosic fabric impregnated with magnesium bromide hexahydrate as flame-retardant". Journal of Thermal Analysis and Calorimetry. 92 (3): 845. doi:10.1007/s10973-007-8928-4. S2CID 94416902.

[9] Seeger, Margarete; Otto, Walter; Flick, Wilhelm; Bickelhaupt, Friedrich; Akkerman, Otto S. (2000). "Magnesium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a15_595. ISBN 3-527-30673-0.

[10] 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.

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