Lanthanum(III) chloride

Lanthanum chloride (LaCl3) is a chemical compound. It is used as a mild Lewis acid to perform chemical reactions that usually require acidic conditions, such as converting aldehydes to acetals, under nearly neutral conditions.

The lanthanide ions are 9 coordinate in the trichloride.

The compound has been identified as a catalyst for the high pressure oxidative chlorination of methane to chloromethane with hydrochloric acid and oxygen. Interestingly in this process the +3 oxidation state of lanthanum remains unchanged.

Uses
Lanthanum chloride can be used to remove phosphates in swimming pools, which helps prevent algae growth.