Aluminium chloride (data page)

Aluminium chloride refers to a chemical compound with the formula AlCl₃. In its anhydrous form, it is a white or yellowish solid, often appearing as hygroscopic crystals. It is deliquescent and fumes in moist air due to hydrolysis, releasing hydrogen chloride gas. Aluminium chloride is commonly encountered as the hexahydrate, AlCl₃·6H₂O, which is a white or colourless crystalline solid.

Anhydrous aluminium chloride is a strong Lewis acid and a valuable catalyst in organic reactions, particularly Friedel-Crafts alkylations and acylations. It exists as a dimer (Al₂Cl₆) in the gas phase and as a polymeric network in the solid state.

The hexahydrate is used in antiperspirants and as a flocculant in water treatment. It's also employed in the preparation of other aluminium compounds.

Safety considerations include that both forms of aluminium chloride can cause irritation to the skin, eyes, and respiratory tract. Anhydrous aluminium chloride reacts violently with water. Appropriate personal protective equipment should be used when handling it.