Description
Aluminium bromide is a compound primarily existing as aluminium tribromide (
AlBr
3
AlBr
3
), composed of aluminum and bromine atoms, and most commonly found as a white to pale yellow, hygroscopic solid with a pungent odor. In its anhydrous form, it can appear lumpy or crystalline, whereas its solutions may appear light yellow.
Chemical Properties and Structure
The molecular formula for aluminium bromide is
AlBr
3
AlBr
3
, with a trigonal planar molecular shape and bond angles of 120° between bromine atoms.
It is highly moisture-sensitive, absorbing water from air and reacting violently with water.
The commonly found dimeric form in solid state is
Al
2
Br
6
Al
2
Br
6
.
It is a strong Lewis acid and Bronsted acid, able to accept electron pairs or donate protons in chemical reactions.
Physical Properties
Appearance: White to yellowish-red solid, lumpy or crystalline.
Odor: Pungent.
Density: Around
3.2
g
/
c
m
3
3.2g/cm
3
as anhydrous solid.
Melting Point: 94–98°C.
Boiling Point: 255–265°C.
Hygroscopic: Absorbs moisture from the air.
Corrosive: Highly corrosive to skin, eyes, and mucous membranes.
Uses
Organic Synthesis: Acts as a Lewis acid catalyst in reactions such as Friedel–Crafts alkylation and acylation (widely used in pharmaceuticals, dyes, and specialty chemicals).
Flame Retardants: Used in the manufacture of flame-retardant plastics and textiles for construction and electronics.
Pharmaceutical Manufacturing: Serves as a reagent for synthesis of active pharmaceutical ingredients.
Analytical Chemistry: Used as a reagent in laboratory settings.
Electroplating: Used in electroplating aluminum onto steel for a smooth, shiny finish.
Safety and Handling
Extremely corrosive and toxic, requiring careful handling and use of protective equipment.
Exposure can cause severe irritation or burns to the skin and eyes.
Aluminium bromide's strong Lewis acidity, moisture sensitivity, and catalytic properties make it important in both laboratory and industrial chemistry, especially in organic and pharmaceutical synthesis.