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
CAS Number	7550-35-8 Y
3D model (JSmol)	Interactive image
ChemSpider	74049 Y
ECHA InfoCard	100.028.582
EC Number	231-439-8
PubChem CID	82050
RTECS number	OJ5755000
UNII	864G646I84 Y
CompTox Dashboard (EPA)	DTXSID20892222
InChI InChI=1S/BrH.Li/h1H;/q;+1/p-1 Y Key: AMXOYNBUYSYVKV-UHFFFAOYSA-M Y InChI=1/BrH.Li/h1H;/q;+1/p-1 Key: AMXOYNBUYSYVKV-REWHXWOFAS
SMILES [Li+].[Br-]
Properties
Chemical formula	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]
Solubility in water	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
Magnetic susceptibility (χ)	−34.3·10−6 cm3/mol[3]
Refractive index (nD)	1.7843 (589 nm)[4]
Structure[5]
Crystal structure	Cubic, Pearson symbol cF8, No. 225
Space group	Fm3m
Lattice constant	a = 0.5496 nm
Thermochemistry[6]
Std molar entropy (S⦵298)	74.3 J/mol K
Std enthalpy of formation (ΔfH⦵298)	−351.2 kJ/mol
Gibbs free energy (ΔfG⦵)	−342.0 kJ/mol
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H317, H319[7]
NFPA 704 (fire diamond)	2 0 0 W
Flash point	Not-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	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). Y verify (what is YN ?) 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] It forms several crystalline hydrates, unlike the other alkali metal bromides.^[10]

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 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 as newer sedatives became available and when some heart patients died after using the salt substitute lithium chloride.^[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.