Calcium bromide
Calcium bromide is the name for compounds with the chemical formula CaBr2(H2O)x. Individual compounds include the anhydrous material (x = 0), the hexahydrate (x = 6), and the rare dihydrate (x = 2). All are white powders that dissolve in water, and from these solutions crystallizes the hexahydrate. The hydrated form is mainly used in some drilling fluids.[1]
Synthesis, structure, and reactions
It is produced by the reaction of calcium oxide, calcium carbonate with bromine in the presence of a reducing agent such as formic acid or formaldehyde:[1]
Solid calcium bromide adopts the rutile structure, featuring octahedral Ca2+ centres bound to six bromide anions, which also bridge to other Ca2+ centres.
When strongly heated in air, calcium bromide reacts with oxygen to produce calcium oxide and bromine:
- 2 CaBr2 + O2 → 2 CaO + 2 Br2
Uses
It is mainly used as dense aqueous solutions for drilling fluids.[1] It is also used in neuroses medication, freezing mixtures, food preservatives, photography and fire retardants.[2]
It minimizes the emission of gaseous mercury in the combustion of coal.[1]
In the laboratory
Calcium bromide forms complexes with triphenylphosphine oxide, allowing for removal of triphenylphosphine oxide from reaction mixtures without the use of chromatography.[3]
References
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