Aluminum Chloride (AlCl3) figures among the most used Lewis acids and is one of the most powerful as well. Widely used as a catalyst, this compound is of major importance in organic chemistry. Examples of aluminum chloride use include alkylation of paraffin and aromatic hydrocarbons by olefins, the formation of complex ketones, aldehydes and carboxylic acid derivatives.
Aluminum chloride can be made by dissolving aluminum or aluminum hydroxide with hydrochloric acid. The solution, on concentration, deposits crystals of AIC13.6H20.
2AI(s) + 6HCl(aq) → 2AlCI3(aq) + 3H2(g)
In crystalline aluminum chloride, there are six water molecules as the water of crystallization. Hence its formula is AlCl3.6H2O.