Calcium bromide

Calcium bromide
Names
IUPAC name
Calcium bromide
Other names
Calcium dibromide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.029.240 Edit this at Wikidata
EC Number
  • 232-164-6
RTECS number
  • EV9328000
UNII
  • InChI=1S/2BrH.Ca/h2*1H;/q;;+2/p-2 checkY
    Key: WGEFECGEFUFIQW-UHFFFAOYSA-L checkY
  • InChI=1/2BrH.Ca/h2*1H;/q;;+2/p-2
    Key: WGEFECGEFUFIQW-NUQVWONBAA
  • Br[Ca]Br
  • [Ca+2].[Br-].[Br-]
Properties
CaBr2
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
Structure
rhomboid
Thermochemistry
75 J/mol K
130 J/mol K
-647.9 kJ/mol
-656.1 kJ/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
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).
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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]

CaO + Br2 + HCO2H → CaBr2 + H2O + CO2

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

  1. ^ a b c d Yoffe, David; Frim, Ron; Ukeles, Shmuel D.; Dagani, Michael J.; Barda, Henry J.; Benya, Theodore J.; Sanders, David C. (2013). "Bromine Compounds". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–31. doi:10.1002/14356007.a04_405.pub2. ISBN 978-3-527-30385-4.
  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.