Lithium bromide (LiBr) is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...

and

bromine Bromine is a chemical element; it has chemical symbol, symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between th ...

. Its extreme

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

character makes LiBr useful as a

desiccant A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccant ...

in certain

air conditioning Air conditioning, often abbreviated as A/C (US) or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature, and in some cases, also controlling the humidity of internal air. Air c ...

systems.Wietelmann, Ulrich and Bauer, Richard J. (2005) "Lithium and Lithium Compounds" in ''Ullmann's Encyclopedia of Industrial Chemistry'' Wiley-VCH: Weinheim.

Production and properties

LiBr is prepared by treating an aqueous suspension of lithium carbonate with hydrobromic acid or by reacting

lithium hydroxide Lithium hydroxide is an inorganic compound with the formula LiOH. It can exist as anhydrous or hydrated, and both forms are white hygroscopic solids. They are soluble in water and slightly soluble in ethanol. Both are available commercially. While ...

with bromine. It forms several crystalline

hydrates In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

, unlike the other alkali metal bromides. 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

. It is also used in absorption chilling along with water (see absorption refrigerator). Solid LiBr is a useful reagent in

organic synthesis Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...

. It is included into oxidation and

hydroformylation In organic chemistry, hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes () from alkenes (). This chemical reaction entails the net addition of a formyl group () and a hydrogen ...

catalysts; it is also used for deprotonation and dehydration of organic compounds containing acidic protons, and for the purification of

steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...

s and

prostaglandin Prostaglandins (PG) are a group of physiology, physiologically active lipid compounds called eicosanoids that have diverse hormone-like effects in animals. Prostaglandins have been found in almost every Tissue (biology), tissue in humans and ot ...

Medical applications

Lithium bromide was used as a

sedative A sedative or tranquilliser is a substance that induces sedation by reducing irritability or Psychomotor agitation, excitement. They are central nervous system (CNS) Depressant, depressants and interact with brain activity, causing its decelera ...

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. Like

lithium carbonate Lithium carbonate is an inorganic compound, the lithium salt of carbonic acid with the chemical formula, formula . This white Salt (chemistry), salt is widely used in processing metal oxides. It is on the WHO Model List of Essential Medicines, Wor ...

and

lithium chloride Lithium chloride is a chemical compound with the formula Li Cl. The salt is a typical ionic compound (with certain covalent characteristics), although the small size of the Li+ ion gives rise to properties not seen for other alkali metal chlorid ...

, it was used as treatment for

bipolar disorder Bipolar disorder (BD), previously known as manic depression, is a mental disorder characterized by periods of Depression (mood), depression and periods of abnormally elevated Mood (psychology), mood that each last from days to weeks, and in ...

Hazards

Lithium salts are

psychoactive A psychoactive drug, psychopharmaceutical, mind-altering drug, consciousness-altering drug, psychoactive substance, or psychotropic substance is a chemical substance that alters psychological functioning by modulating central nervous system acti ...

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

References

Cited sources

External links

* {{Authority control Bromides Lithium salts Metal halides Mood stabilizers Sedatives GABAA receptor positive allosteric modulators Alkali metal bromides Rock salt crystal structure