CeCl3

Cerium(III) chloride, also known as cerous chloride, has the chemical formula CeCl3. It is a white, hygroscopic solid. It is soluble in water and alcohols. Cerium(III) chloride is often encountered in its hydrated form, CeCl3·7H2O, which is a crystalline solid. The anhydrous form is less common and is prepared by heating the hydrated salt in a stream of hydrogen chloride gas or by other specialized methods.

Cerium(III) chloride is primarily used as a source of cerium in various applications. It serves as a precursor in the synthesis of other cerium compounds, including cerium oxides, which are important in catalysis, as phosphors, and in glass polishing. It is also used in metallurgy, particularly in the production of cerium alloys. In organic chemistry, anhydrous cerium(III) chloride has found application as a Lewis acid catalyst, facilitating various organic reactions such as aldol condensations and Diels-Alder reactions. Its Lewis acidity can be tuned by its coordination environment.

The compound can be synthesized by reacting cerium(III) oxide or cerium(III) carbonate with hydrochloric acid. The resulting solution is then evaporated and crystallized to obtain the hydrated form. Anhydrous CeCl3 can be obtained by dehydrating the hydrated salt under specific conditions. Care must be taken during handling due to its hygroscopic nature.