Aluminum Bromide

Chemical properties

White Crystalline Powder

Physical properties

Colorless crystalline solid in anhydrous form; melts at 97.5°C; boils at 256°C;density 3.01 g/cm3 at 25°C; moisture sensitive, fumes in air; soluble in water (reacts violently in cold water, and decomposes in hot water, alcohols, acetone, hexane, benzene, nitrobenzene, carbon disulfide and many other organic sol_x0002_vents).

The Uses of Aluminum Bromide

Alkylation, bromination and isomerization catalyst in organic synthesis.Aluminum bromide acts as a strong Lewis acid and is used in Lewis acid-promoted reactions such as epoxide ring openings. It is used as a catalyst for Friedel-Crafts alkylation reaction. It also finds application in bromination and isomerization reactions in organic synthesis. It is also used in polymerization reaction to prepare poly(o-xylene)from benzocyclobutene.

The Uses of Aluminum Bromide

Anhydrous: bromination, alkylation, and isomerization catalyst in organic synthesis.

Preparation

Prepared from bromine and metallic aluminum.
2Al + 3Br2 ——? Al2Br6 (anhydrous).

General Description

A white to yellowish-red, lumpy solid with a pungent odor.

Reactivity Profile

An acid. May catalyze organic reactions. Corrosive to metals. Solutions of aluminum bromide in dichloromethane should be kept cold as a potentially dangerous exothermic halide exchange reaction occurs on warming, [Acc. Chem. Res., 1986, 19(3), 78].

Hazard

The anhydrous form reacts violently with water; corrosive to skin.

Health Hazard

CORROSIVE and/or TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Fire will produce irritating, corrosive and/or toxic gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Contact with molten substance may cause severe burns to skin and eyes. Runoff from fire control or dilution water may cause pollution.

Fire Hazard

EXCEPT FOR ACETIC ANHYDRIDE (UN1715), THAT IS FLAMMABLE, some of these materials may burn, but none ignite readily. May ignite combustibles (wood, paper, oil, clothing, etc.). Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff. Flammable/toxic gases may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water. Substance may be transported in a molten form.

Safety Profile

A toxic, corrosive material. See also BROMIDES and ALUMINUM COMPOUNDS. Mixtures with sodium or potassium explode violently upon impact. When heated to decomposition it emits toxic fumes of Br-. Do not add H2O to anhydrous material. Hydrolysis can be violent.

Purification Methods

Reflux it and then distil it from pure aluminium chips in a stream of nitrogen into a flask containing more of the chips. It is then distilled under vacuum into ampoules [Tipper & Walker J Chem Soc 1352 1959]. Anhydrous conditions are essential, and the white to very light brown solid distillate can be broken into lumps in a dry-box (under nitrogen). It fumes in moist air. [Becher in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 812-813 1963.]