Magnesium bromide is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one elemen ...

of magnesium and

bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simila ...

, with the chemical formula . It is white and

deliquescent Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

crystalline solid. It is often used as a mild sedative and as an

anticonvulsant Anticonvulsants (also known as antiepileptic drugs or recently as antiseizure drugs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment o ...

for treatment of nervous disorders. It is water-soluble and somewhat soluble in alcohol. It can be found naturally in small amounts in some minerals such as: bischofite and carnallite, and in sea water, such as that of the

Dead Sea The Dead Sea ( he, יַם הַמֶּלַח, ''Yam hamMelaḥ''; ar, اَلْبَحْرُ الْمَيْتُ, ''Āl-Baḥrū l-Maytū''), also known by other names, is a salt lake bordered by Jordan to the east and Israel and the West Bank t ...

.Gruyter, W. Concise Encyclopedia Chemistry, Walter de Gruyter & Company: Berlin, 1993; 612Lewis, R.J. Hawley’s Condensed Chemical Dictionary, 15th ed.; John Wiley &Sons Inc.:New York, 2007; 777

Synthesis

Magnesium bromide can be synthesized by treating with

magnesium oxide Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

(and related basic salts) with

hydrobromic acid Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at and contains 47.6% HBr by mass, which is 8.77 mol/L. H ...

. It can also be made by reacting magnesium carbonate and hydrobromic acids, and collecting the solid left after evaporation. As suggested by its easy conversion to various hydrates, anhydrous is a

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

. In the

coordination polymer A coordination polymer is an inorganic or organometallic polymer structure containing metal cation centers linked by ligands. More formally a coordination polymer is a coordination compound with repeating coordination entities extending in 1, 2, o ...

with the formula MgBr₂(dioxane)₂, Mg²⁺ adopts an octahedral geometry.

Uses

Magnesium bromide is used as a

catalyst Catalysis () is the process of increasing the reaction rate, rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the ...

in some

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

, e.g., in

aldol reaction The aldol reaction is a means of forming carbon–carbon bonds in organic chemistry. Discovered independently by the Russian chemist Alexander Borodin in 1869 and by the French chemist Charles-Adolphe Wurtz in 1872, the reaction combines two car ...

. In organosilicon chemistry, magnesium bromide forms adducts . Magnesium bromide also has been used as a tranquilizer. Magnesium bromide modifies the catalytic properties of palladium on charcoal. Magnesium bromide hexahydrate has properties as a flame retardant. It was found that if 0.125 mol/L of magnesium bromide hexahydrate was added to a cotton material it acted as a flame retardant.

References

{{bromine compounds Bromides Magnesium compounds Alkaline earth metal halides