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]

Calcium bromide
IUPAC name
Calcium bromide
Other names
Calcium dibromide
3D model (JSmol)
ECHA InfoCard 100.029.240
EC Number
  • 232-164-6
RTECS number
  • EV9328000
  • InChI=1S/2BrH.Ca/h2*1H;/q;;+2/p-2 Y
  • InChI=1/2BrH.Ca/h2*1H;/q;;+2/p-2
  • Br[Ca]Br
  • [Ca+2].[Br-].[Br-]
Molar mass 199.89 g/mol (anhydrous)
235.98 g/mol (dihydrate)
Appearance anhydrous is hygroscopic colorless crystals
sharp saline taste
Density 3.353 g/cm3
Melting point 730 °C (1,350 °F; 1,000 K)
Boiling point 1,815 °C (3,299 °F; 2,088 K) (anhydrous)
810 °C (dihydrate)
125 g/100 mL (0 °C)
143 g/100 mL (20 °C)
312 g/100 mL (100 °C)
Solubility in alcohol, acetone soluble
Acidity (pKa) 9
-73.8·10−6 cm3/mol
75 J/mol K
130 J/mol K
-647.9 kJ/mol
-656.1 kJ/mol
NFPA 704 (fire diamond)
Lethal dose or concentration (LD, LC):
4100 mg/kg (rat, oral)
1580 mg/kg (mouse, subcutaneous)
Related compounds
Other anions
Calcium fluoride
Calcium chloride
Calcium iodide
Other cations
Beryllium bromide
Magnesium 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

Synthesis, structure, and reactions

It is produced by the reaction of calcium oxide, calcium carbonate with hydrobromic acid or the reaction of calcium metal with elemental bromine.[1]

It adopts the rutile structure, featuring octahedral Ca centres bound to six bromide anions, which also bridge to other Ca centres.

When strongly heated in air, calcium bromide will react with oxygen to produce calcium oxide and bromine:

2 CaBr2 + O2 → 2 CaO + 2 Br2

In this reaction, the oxygen oxidizes the bromide to bromine.


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]

Calcium bromide has been shown to undergo complexation with triphenylphosphine oxide, allowing for removal of triphenylphosphine oxide from reaction mixtures without the use of chromatography.[3]


  1. Michael J. Dagani, Henry J. Barda, Theodore J. Benya, David C. Sanders “Bromine Compounds” Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a04_405
  2. "Chemical Land 21". Retrieved 25 December 2008.
  3. Rodríguez Hergueta, Antonio (2022). "Easy Removal of Triphenylphosphine Oxide from Reaction Mixtures by Precipitation with CaBr2". Organic Process Research & Development. 26 (6): 1845–1853. doi:10.1021/acs.oprd.2c00104. S2CID 249558328.
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