Cerium(III) chloride

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 to form hydrates, which may be of variable composition.The hexa- and heptahydrate CeCl₃·7H₂O are known.^[1] All forms are highly soluble in water, and the anhydrous derivative is soluble in ethanol and acetone.^[2][3]

Cerium(III) chloride

Cerium(III) chloride
Names
IUPAC names Cerium(III) chloride Cerium trichloride
Other names Cerous chloride
Identifiers
CAS Number	7790-86-5 Y 18618-55-8 (heptahydrate) Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:35458 Y
ChemSpider	23038 Y
ECHA InfoCard	100.029.298
EC Number	232-227-8
Gmelin Reference	1828
PubChem CID	24636
UNII	TH8E3IE00V Y 188BE3J495 (heptahydrate) Y
CompTox Dashboard (EPA)	DTXSID1037199
InChI InChI=1S/Ce.3ClH/h;3*1H/q+3;;;/p-3 Y Key: VYLVYHXQOHJDJL-UHFFFAOYSA-K Y InChI=1/Ce.3ClH/h;3*1H/q+3;;;/p-3 Key: VYLVYHXQOHJDJL-DFZHHIFOAZ
SMILES [Cl-].[Cl-].[Cl-].[Ce+3]
Properties
Chemical formula	CeCl3
Molar mass	246.48 g/mol (anhydrous) 372.58 g/mol (heptahydrate)
Appearance	fine white powder
Density	3.97 g/cm3
Melting point	817 °C (1,503 °F; 1,090 K) (anhydrous) 90 °C (heptahydrate, decomposes)
Boiling point	1,727 °C (3,141 °F; 2,000 K)
Solubility	soluble in alcohol
Magnetic susceptibility (χ)	+2490.0·10−6 cm3/mol
Structure
Crystal structure	hexagonal (UCl3 type), hP8
Space group	P63/m, No. 176
Coordination geometry	Tricapped trigonal prismatic (nine-coordinate)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H315, H318, H319, H335, H410
Precautionary statements	P261, P264, P271, P273, P280, P302+P352, P304+P340, P305+P351+P338, P310, P312, P321, P332+P313, P337+P313, P362, P391, P403+P233, P405, P501
Flash point	Non-flammable
Related compounds
Other anions	Cerium(III) oxide Cerium(III) fluoride Cerium(III) bromide Cerium(III) iodide
Other cations	Lanthanum(III) chloride Praseodymium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation of anhydrous CeCl3

Simple rapid heating of the hydrate alone may cause small amounts of hydrolysis.^[4]

A useful form of anhydrous CeCl₃ can be prepared if care is taken to heat the heptahydrate gradually to 140 °C (284 °F) over many hours under vacuum.^[2][5][6] This may or may not contain a little CeOCl from hydrolysis, but it is suitable for use with organolithium and Grignard reagents. Pure anhydrous CeCl₃ can be made by dehydration of the hydrate either by slowly heating to 400 °C (752 °F) with 4–6 equivalents of ammonium chloride under high vacuum,^[4][7][8][9] or by heating with an excess of thionyl chloride for three hours.^[4][10] The anhydrous halide may alternatively be prepared from cerium metal and hydrogen chloride.^[11][12] It is usually purified by high temperature sublimation under high vacuum. Soxhlet extraction of CeCl₃ with thf gives CeCl₃(thf)_1.04.^[13]

Uses

Cerium(III) chloride can be used as a starting point for the preparation of other cerium salts, such as the Lewis acid cerium(III) trifluoromethanesulfonate.^[14]

Organic synthesis

Cerium(III) chloride is a reagent in several procedures used in organic synthesis.^[15] Luche reduction^[16] of alpha, beta-unsaturated carbonyl compounds has become a popular method in organic synthesis, where CeCl₃·7H₂O is used in conjunction with sodium borohydride. For example, carvone gives only the allylic alcohol 1 and none of the saturated alcohol 2. Without CeCl₃, a mixture of 1 and 2 is formed.

It can also deprotect MEM group to alcohol in the presence of other acetal protecting groups (e.g. THP.)

Another important use in organic synthesis is for alkylation of ketones, 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: ^[5]

It is reported that organolithium reagents work more effectively in this reaction than do Grignard reagents.^[5]