Aluminum Bromide

Aluminum bromide is an inorganic binary compound. The substance is a salt of aluminum and bromine-hydrogen acid. Outside, these are colorless monoclinic crystals. In solid and liquid state, it exists in form of a dimer. Its molar/atomic mass is 266.69.
The anhydrous aluminum bromide is a colorless crystalline substance melting at temperature of 97,5 °C. Its temperature of boiling in a liquid state is 255 °C.

Aluminum Bromide

The substance is highly hygroscopic: in the open air, it becomes diffuse, easily absorbing moisture with formation of the hexahydrate AlBr3•6H2O. It is well soluble in water, alcohol, carbon sulphide, acetone. The interaction of aluminum bromide with water is accompanied by an extremely violent reaction with emission of a large quantity of heat and a leakage of reaction mass. It fumes in the open air.

The commercial use of aluminum bromide is relatively insignificant at the moment. Aluminum bromide belongs as the main component to xylene electrolytes for electric precipitation of aluminum coatings. The anhydrous aluminum bromide is used in organic synthesis, in particular, in the alkylation reaction or Friedel-Crafts reaction by analogy with aluminum chloride.

While contacting with the skin, aluminum bromide can scald. The compound is moderately poisonous.

Uses

The application of aluminum bromide is relatively small. However, aluminum bromide is the main component of xylol electrolytes for electric precipitation of aluminum coatings. The anhydrous aluminum bromide is also used in organic synthesis, in particular, in an alkylation reaction, which is also called Friedel-Crafts acylation. This compound can be catalyst in a bromo-alkanes` isomerizating reaction. Aluminum bromide can also be used as bromating agent, for example, in a reaction with chloroform.

Formula for Aluminum Bromide

The structure of a molecule of aluminum bromide represents the twinned tetrahedrons, in the center of which the aluminum atoms covalently bound to bromine atoms are located. The coordination number of aluminum bromide in a molecule is equal to 4.

In solid and liquid phase, aluminum bromide exists in form of a dimer Al2Br6 partially dissociating in AlBr3.

Its empirical formula (Hill’s system) is the following: AlBr3.

Empirical formula Aluminum Bromide

Formula for Aluminum Bromide

Its structural formula is: Al2Br6

Structural formula Aluminum Bromide

The anhydrous aluminum bromide is received by interaction of elements (Al and Br2) at heating:

2Al + 3Br2 = Al2Br6

Its aqueous solution can be received by a reaction of aluminum shavings with bromine-hydrogen acid:

2Al + 6HBr = 2AlBr3 + 3H2

Properties for Aluminum Bromide

Molar mass     266.69 g/mol
Melting Point  97.8 °C (208.0 °F; 370.9 K)
Boiling Point  265 °C (509 °F; 538 K)
Density       3.205 g/cm3