Cerium(III) chloride (CeCl₃), also known as cerous chloride or cerium trichloride, is a compound of cerium and chlorine. It is a white hygroscopic salt; it rapidly absorbs water on exposure to moist air to form a

hydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

, which appears to be of variable composition, though the heptahydrate CeCl₃·7H₂O is known. It is highly soluble in water, and (when anhydrous) it is soluble in ethanol and acetone.

Preparation of waterless CeCl₃

Simple rapid heating of the hydrate alone may cause small amounts of hydrolysis. A useful form of

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...

CeCl₃ can be prepared if care is taken to heat the heptahydrate gradually to over many hours under vacuum. This may or may not contain a little CeOCl from hydrolysis, but it is suitable for use with organolithium and

Grignard reagent A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide ...

s. Pure anhydrous CeCl₃ can be made by dehydration of the hydrate either by slowly heating to with 4–6 equivalents of ammonium chloride under high vacuum, or by heating with an excess of thionyl chloride for three hours. The anhydrous

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluor ...

may alternatively be prepared from cerium metal and hydrogen chloride. It is usually purified by high temperature sublimation under high vacuum.

Uses

Cerium(III) chloride can be used as a starting point for the preparation of other cerium salts, such as the

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

cerium(III) trifluoromethanesulfonate Lanthanide triflates are triflate salts of the lanthanides. These salts have been investigated for application in organic synthesis as Lewis acid catalysts. These catalysts function similarly to aluminium chloride or ferric chloride, but are sta ...

, used for Friedel-Crafts acylations. It is also used itself as a Lewis acid, for example as a catalyst in Friedel-Crafts alkylation reactions.

Luche reduction Luche reduction is the selective organic reduction of α,β-unsaturated ketones to allylic alcohols with sodium borohydride (NaBH4) and lanthanide chlorides, mainly cerium(III) chloride (CeCl3), in methanol or ethanol. The Luche reduction ca ...

of alpha, beta-unsaturated carbonyl compounds has become a popular method in

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

, where CeCl₃·7H₂O is used in conjunction with sodium borohydride. For example, carvone gives only the allylic

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

1 and none of the

saturated Saturation, saturated, unsaturation or unsaturated may refer to: Chemistry * Saturation, a property of organic compounds referring to carbon-carbon bonds ** Saturated and unsaturated compounds **Degree of unsaturation ** Saturated fat or fatty ac ...

2. Without CeCl₃, a mixture of 1 and 2 is formed. Luche reduction

Another important use in

is for alkylation of

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

s, which would otherwise form enolates if simple organolithium reagents were to be used. For example, compound 3 would be expected to simply form an enolate without CeCl₃ being present, but in the presence of CeCl₃ smooth alkylation occurs: Cerium alkylation

It is reported that organolithium reagents work more effectively in this reaction than do

Preparation of waterless CeCl₃

Uses

References

Further reading

Preparation of waterless CeCl3

Uses

References

Further reading

Preparation of waterless CeCl₃