ChemicalBook > Product Catalog > Inorganic chemistry > Inorganic salts > Metal halide and Halogen salt > Metal bromide and salt > Magnesium bromide
Magnesium bromide Chemical Properties
- Melting point:711 °C(lit.)
- Boiling point:1248.47°C (estimate)
- Density 3.72 g/mL at 25 °C(lit.)
- form Powder
- color off-white
- Specific Gravity3.72
- Water Solubility g/100g H2O: 100.6 (25°C), 125.4 (100°C); solid phase, MgBr2 ·6H2O [KRU93]
- Merck 13,5681
- CAS DataBase Reference7789-48-2(CAS DataBase Reference)
- NIST Chemistry ReferenceMagnesium dibromide(7789-48-2)
- EPA Substance Registry SystemMagnesium bromide (MgBr2) (7789-48-2)
Magnesium bromide Usage And Synthesis
- Occurrence and UsesMagnesium bromide occurs in sea water, surface and subterranean brines, and salt deposits. It is an electrolyte component in certain dry cells. In medicine, it is a sedative and anticonvulsant for treatment of nervous disorder. It also is used in organic synthesis forming several addition compounds.
- Physical PropertiesThe anhydrous MgBr2 is a white crystalline substance; hexagonal crystals; deliquescent; density 3.72 g/cm3; melts at 700°C; highly soluble in water (101.5g/100mL at 20°C); moderately soluble in methanol and ethanol (21.8 and 6.9 g/mL at 20°C, respectively).
The hexahydrate, MgBr2•6H2O consists of colorless monoclinic crystals; bitter taste; hygroscopic; fluoresce in x-rays; density 2.07 g/cm3; melts at 172.4°C; intensely soluble in water, 316 g/100 mL at 0°C; dissolves in methanol and ethanol; slightly soluble in ammonia solution.
- PreparationMagnesium bromide is prepared by treating magnesium oxide with hydrobromic acid and subsequent crystallization above 0°C. The product is hexahydrate, MgBr2•6H2O:
MgO + 2HBr → MgBr2 + H2O
The anhydrous MgBr2 may be obtained by heating the hexahydrate with dry hydrogen bromide gas. Magnesium bromide also can be made from its elements. Heating magnesium metal with bromine vapor yields the salt:
Mg + Br2 → MgBr2
Magnesium bromide, like the chloride salt, is obtained from sea water (see Magnesium and Magnesium chloride). In this process, magnesium hydroxide precipitated from sea water is neutralized with hydrobromic acid, and MgBr2 is obtained by crystallization.
- Chemical PropertiesColorless, very deliquescent crystals; bitter taste. Soluble in water; slightly soluble in alcohol.
- UsesOrganic syntheses, medicine (sedative).
- UsesThe major use of MgBr2 has been in the commercial
production of bromine. The Dow process is an electrolytic
method of bromine extraction from brine, and
was Herbert Dow’s second revolutionary process for
generating bromine commercially (1889).
Magnesium bromide has also been used in organic syntheses. An efficient and environmentally friendly procedure for the one-pot synthesis of tetrahydropyrimidines from aldehydes, a-diketones and urea/thiourea by using magnesium bromide as an inexpensive and easily available catalyst under solvent-free conditions has been described. Compared with the classical Biginelli reaction conditions, this new method has the advantage of good to excellent yields (74%–94%) and short reaction times (45–90 min). The structure of the Biginelli reaction product from a-diketone, salicylaldehyde and urea has been proposed to possess an oxygen bridge by cyclization (intramolecular Michael addition).
- PreparationMagnesium bromide is prepared by treating MgO
with hydrobromic acid and then crystallization
above 0.0°C in solution. The product is the hexahydrate
The anhydrous form may also be prepared by heating the hexah
- Purification MethodsCrystallise it from EtOH or H2O (3.3g/mL). Dry it in a vacuum at ~150o, or heat the hydrate in a stream of HCl. It is very deliquescent. [Ehrlich in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 909 1963.]
Magnesium bromide Preparation Products And Raw materials
- (2-(1-PYRROLIDINYLMETHYL)PHENYL)MAGNESIUM BROMIDE (1-Methyldecyl)magnesium bromide (1-Methyltridecyl)magnesium bromide Magnesium Vinylmagnesium bromide Magnesium bromide Cyclopropylmagnesium bromide PHENYLMAGNESIUM BROMIDE ETHYLMAGNESIUM BROMIDE Methylmagnesium bromide 1,2-Dibromoethane Magnesium sulfate Magnesium oxide Magnesium sulfate heptahydrate ALLYLMAGNESIUM BROMIDE Ethidium bromide Magnesium acetate Magnesium nitrate
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