Instead HCl is lost leaving aluminium hydroxide or alumina (aluminium oxide):

[Al(H2O)6]Cl3 → Al(OH)3 + 3 HCl + 3 H2OLike metal aquo complexes, aqueous AlCl3 is acidic owing to the ionization of the aquo ligands:

[Al(H2O)6]3+ ⇌ [Al(OH)(H2O)5]2+ + H+Aqueous solutions behave similarly to other aluminium salts containing hydrated Al3+ ions, giving a gelatinous precipitate of aluminium hydroxide upon reaction with dilute sodium hydroxide:

AlCl3 + 3 NaOH → Al(OH)3 + 3 NaCl

Synthesis
Aluminium chloride is manufactured on a large scale by the exothermic reaction of aluminium metal with chlorine or hydrogen chloride at temperatures between 650 to 750 °C (1,202 to 1,382 °F). 2 Al + 3 Cl2 → 2 AlCl3
2 Al + 6 HCl → 2 AlCl3 + 3 H2Aluminium chloride may be formed via a single displacement reaction between copper chloride and aluminium metal. 2 Al + 3 CuCl2 → 2 AlCl3 + 3 CuIn the US in 1993, approximately 21,000 tons were produced, not counting the amounts consumed in the production of aluminium.Hydrated aluminium trichloride is prepared by dissolving aluminium oxides in hydrochloric acid. Metallic aluminium also readily dissolves in hydrochloric acid ─ releasing hydrogen gas and generating considerable heat. Heating this solid does not produce anhydrous aluminium trichloride, the hexahydrate decomposes to aluminium hydroxide when heated:

[Al(H2O)6]Cl3 → Al(OH)3 + 3 HCl + 3 H2OAluminium also forms a lower chloride, aluminium(I) chloride (AlCl), but this is very unstable and only known in the vapour phase. Natural occurrence
Anhydrous aluminium chloride is not found as a mineral. The hexahydrate, however, is known as the rare mineral chloraluminite.
Aluminium chloride monomer belongs to the point group D3h in its monomeric form and D2h in its dimeric form. Hexahydrate
The hexahydrate consists of octahedral [Al(H2O)6]3+ cation centers and chloride anions (Cl−) as counterions. Hydrogen bonds link the cation and anions. The hydrated form of aluminium chloride has an octahedral molecular geometry, with the central aluminium ion surrounded by six water ligand molecules. Being coordinatively saturated, the hydrate is of little value as a catalyst in Friedel-Crafts alkylation and related reactions. Uses
Alkylation and acylation of arenes
AlCl3 is a common Lewis-acid catalyst for Friedel-Crafts reactions, both acylations and alkylations. Important products are detergents and ethylbenzene. These types of reactions are the major use for aluminium chloride, for example, in the preparation of anthraquinone (used in the dyestuffs industry) from benzene and phosgene. In the general Friedel-Crafts reaction, an acyl chloride or alkyl halide reacts with an aromatic system as shown:
The alkylation reaction is more widely used than the acylation reaction, although its practice is more technically demanding. For both reactions, the aluminium chloride, as well as other materials and the equipment, should be dry, although a trace of moisture is necessary for the reaction to proceed. Detailed procedures are available for alkylation and acylation of arenes. A general problem with the Friedel-Crafts reaction is that the aluminium chloride catalyst sometimes is required in full stoichiometric quantities, because it complexes strongly with the products. This complication sometimes generates a large amount of corrosive waste.