Lithium bromide

Lithium bromide, or LiBr, is a chemical compound of lithium and bromine. Its extreme hygroscopic character makes LiBr useful as a desiccant in certain air conditioning systems.

Production and properties
LiBr is prepared by treatment of lithium carbonate with hydrobromic acid. The salt forms several crystalline hydrates, unlike the other alkali metal bromides. 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
Lithium bromide is used in air-conditioning systems as desiccant. Lithium bromide is used as a salt in absorption chilling along with water (see absorption refrigerator). Otherwise the salt is useful as a reagent in organic synthesis. For example it reversibly forms adducts with some pharmaceuticals.

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.

Like lithium carbonate and lithium chloride, it was used as treatment for bipolar disorder.

Doses as low as 225 mg/day of LiBr can lead to bromism.

Hazards
Lithium salts are psychoactive and somewhat corrosive. When lithium bromide is dissolved into water, the reaction is very exothermic.