Lithium bromide

Lithium bromide (LiBr) is a chemical compound of lithium and bromine. Its extreme hygroscopic character makes LiBr useful as a desiccant in certain air conditioning systems.[9]

Lithium bromide

__ Li+     __ Br−
Names
IUPAC name
Lithium bromide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.582
EC Number
  • 231-439-8
RTECS number
  • OJ5755000
UNII
Properties
LiBr
Molar mass 86.845 g/mol[1]
Appearance White hygroscopic solid[1]
Density 3.464 g/cm3[1]
Melting point 550 °C (1,022 °F; 823 K)[1]
Boiling point 1,300 °C (2,370 °F; 1,570 K)[1]
143 g/100 mL (0 °C)
166.7 g/100 mL (20 °C)
266 g/100 mL (100 °C)[2]
Solubility soluble in methanol, ethanol,[1] ether,[1] acetone
slightly soluble in pyridine
−34.3·10−6 cm3/mol[3]
1.7843 (589 nm)[4]
Structure[5]
Cubic, Pearson symbol cF8, No. 225
Fm3m
a = 0.5496 nm
Thermochemistry[6]
74.3 J/mol K
-351.2 kJ/mol
-342.0 kJ/mol
Hazards
GHS pictograms
GHS Signal word Warning
H315, H317, H319[7]
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
2
0
Flash point Not-flammable
Lethal dose or concentration (LD, LC):
1800 mg/kg (oral, rat)[8]
Related compounds
Other anions
 Lithium fluoride
Lithium chloride
Lithium iodide
Other cations
 Sodium bromide
Potassium bromide
Rubidium bromide
Caesium 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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Infobox references

Production and properties
Solubility of LiBr in water as a function of temperature
Phase diagram of LiBr

LiBr is prepared by treating an aqueous suspension of lithium carbonate with hydrobromic acid or by reacting lithium hydroxide with bromine.[9] The salt forms several crystalline hydrates, unlike the other alkali metal bromides.[10] The anhydrous salt forms cubic crystals similar to common salt (sodium chloride).

Lithium hydroxide and hydrobromic acid (aqueous solution of hydrogen bromide) will precipitate lithium bromide in the presence of water.

LiOH + HBr → LiBr + H2O

Uses

A 50–60% aqueous solution of lithium bromide is used in air-conditioning systems as desiccant. It is also used as a salt in absorption chilling along with water (see absorption refrigerator). Solid LiBr is a useful reagent in organic synthesis. It is included into oxidation and hydroformylation catalysts; it is also used for deprotonation and dehydration of organic compounds containing acidic protons, and for the purification of steroids and prostaglandins.[9]

Medical applications

Lithium bromide was used as a sedative, beginning in the early 1900s, but it fell into disfavor in the 1940s when some heart patients died after using it as a salt substitute.[11] Like lithium carbonate and lithium chloride, it was used as treatment for bipolar disorder.

Hazards

Lithium salts are psychoactive and somewhat corrosive. Heat is quickly generated when lithium bromide is dissolved into water because it has a negative enthalpy of solution.

References
  1. Haynes, p. 4.70
  2. Haynes, p. 5.169
  3. Haynes, p. 4.128
  4. Haynes, p. 10.249
  5. Seifert, H.-J.; Dau, E. (1972). "Über die Systeme Alkalimetallbromid/Mangan(II)-bromid". Zeitschrift für Anorganische und Allgemeine Chemie. 391 (3): 302–312. doi:10.1002/zaac.19723910311.
  6. Haynes, p. 5.25
  7. Lithium bromide. SIgma Aldrich
  8. Chambers, Michael. "ChemIDplus – 7550-35-8 – AMXOYNBUYSYVKV-UHFFFAOYSA-M – Lithium bromide – Similar structures search, synonyms, formulas, resource links, and other chemical information". chem.sis.nlm.nih.gov. Retrieved 3 April 2018.
  9. Wietelmann, Ulrich and Bauer, Richard J. (2005) "Lithium and Lithium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH: Weinheim. doi:10.1002/14356007.a15_393.pub2
  10. Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, ISBN 0-12-352651-5
  11. "Bipolar Disorder: Treatment and Care". webmd.com. Retrieved 3 April 2018.

Cited sources
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