Lithium bromide

Description

Lithium bromide is an extremely hygroscopic chemical commonly used in absorption chillers, where water is the refrigerant. Because of its high affinity to water, LiBr can easily absorb excess vapor, making the system an environmentally friendly non-CFC alternative.

Chemical properties

White cubic crystals; hygroscopic; refractive index 1.784; density 3.464 g/cm3; melts at 550°C; vaporizes at 1,265°C; highly soluble in water (145g/100g at 4°C), much greater solubility in hot water (254g/100g at 90°C); soluble in methanol, ethanol and ether; slightly soluble in pyridine; vapor pressure of aqueous solutions at 52 and 68% concentrations at 25°C are 5 and 0.7 torr, respectively.

Physical properties

White cubic crystals; hygroscopic; refractive index 1.784; density 3.464 g/cm³; melts at 550°C; vaporizes at 1,265°C; highly soluble in water (145g/100g at 4°C), much greater solubility in hot water (254g/100g at 90°C); soluble in methanol, ethanol and ether; slightly soluble in pyridine; vapor pressure of aqueous solutions at 52 and 68% concentrations at 25°C are 5 and 0.7 torr, respectively.

The Uses of Lithium bromide

As humectant, in air-conditioning systems. An aqueous solution of lithium bromide containing about 50 % lithium bromide is used as an absorbent in large-scale absorption air conditioning equipment. Lithium bromide is also used in limited amounts by the pharmaceutical industry for dehydrobromination of organic compounds to form olefins.

The Uses of Lithium bromide

Lithium Bromide finds use as a desiccant in industrial air conditioning systems and industrial drying agents.

The Uses of Lithium bromide

It is used for reconstitution of brines, as swelling agent for proteins and as electrolyte component in lithium battery. Used as brazing and welding flux. Lithium bromide is used as catalyst for the condensation of carbonyl compounds with active methylene compounds in the absence of solvent, operating medium for air-conditioning and industrial drying system. Also used in manufacturing pharmaceuticals and alkylation process. It also plays an important role in the synthesis of dihydropyrimidinones.

What are the applications of Application

Lithium bromide is an inexpensive catalyst that opens epoxide rings by amines at room temperature

Definition

ChEBI: A lithium salt in which the counterion is bromide. The anhydrous salt forms cubic crystals similar to common salt.

Preparation

Lithium bromide may be prepared by the reaction of lithium hydroxide monohydrate or lithium carbonate with hydrobromic acid. The resultant solution of lithium bromide may be evaporated and cooled to crystallize a hydrate of lithium bromide, the composition of which depends on the final temperature. The lithium bromide hydrate may be filtered from the mixture and carefully dried by the application of heat in a vacuum desiccator to avoid melting the hydrate.

General Description

LiBr/Chlorotrimethylsilane reagent participates in the conversion of alcohols to bromides.

Flammability and Explosibility

Non flammable

Purification Methods

Crystallise it several times from water or EtOH, then dry it under high vacuum for 2 days at room temperature, followed by drying at 100o. Its solubility in H2O is 167% at ~20o, and 250% at ~100o. It is deliquescent and should be stored in a tightly stoppered vessel.