Lanthanum(III) chloride

Lanthanum(III) chloride

Names
Other names Lanthanum trichloride
Identifiers
CAS Number	10099-58-8 20211-76-1 (heptahydrate)
3D model (Jmol)	Interactive image
ChemSpider	58275
ECHA InfoCard	100.030.202
PubChem	64735
UNII	04M8624OXV
InChI InChI=1S/3ClH.La/h3*1H;/q;;;+3/p-3 Key: ICAKDTKJOYSXGC-UHFFFAOYSA-K InChI=1/3ClH.La/h3*1H;/q;;;+3/p-3 Key: ICAKDTKJOYSXGC-DFZHHIFOAJ
SMILES Cl[La](Cl)Cl
Properties
Chemical formula	LaCl3
Molar mass	245.26 g/mol (anhydrous) 353.36 g/mol (hexahydrate) 371.37 g/mol (heptahydrate)
Appearance	white odorless powder hygroscopic
Density	3.84 g/cm^3
Melting point	858 °C (1,576 °F; 1,131 K) (anhydrous)[1]
Boiling point	1,000 °C (1,830 °F; 1,270 K) (anhydrous)
Solubility in water	very soluble
Solubility	soluble in ethanol (heptahydrate)
Structure
Crystal structure	hexagonal (UCl3 type), hP8
Space group	P63/m, No. 176
Coordination geometry	Tricapped trigonal prismatic,(nine-coordinate)
Related compounds
Other anions	Lanthanum oxide
Other cations	Cerium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Lanthanum chloride is the inorganic compound with the formula LaCl₃. It is a common salt but is mainly used in research. It is a white solid that is highly soluble in water and alcohols.

Structure

The La³⁺ centre is 9-coordinate in the trichloride. The structure is similar to that for uranium trichloride.

Preparation and reactions

It forms upon union of the elements, but a more commonly used method involves heating a mixture of lanthanum(III) oxide and ammonium chloride at 200-250 °C:^[2]

La₂O₃ + 6 NH₄Cl → 2 LaCl₃ + 6 NH₃ + 2 H₂O

From the trichloride, one can produce the other trihalides by exchange. Reduction with potassium gives metallic lanthanum.

Uses

Lanthanum chloride does not enjoy many applications. A possible application involves the precipitation of phosphate from solutions, e.g. in swimming pools to prevent algae growth. It has also shown use as a filter aid and an effective flocculent. Lanthanum chloride is also used in biochemical research to block the activity of divalent cation channels, mainly calcium channels. Doped with cerium, it is used as a scintillator material.

In organic synthesis, lanthanum trichloride functions as a mild Lewis acid for converting aldehydes to acetals.

The compound has been identified as a catalyst for the high pressure oxidative chlorination of methane to chloromethane with hydrochloric acid and oxygen.^[3]

This compound is also used in Gamma Detectors, is one of the smallest sized (massed) meters of the inorganic compounds used for Gamma Ray Detectors.

Lanthanum chloride is also frequently used as an ionisation suppressant in Atomic Emission spectroscopy.

References

1. Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.
2. Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY.
3. Podkolzin SG, Stangland EE, Jones ME, Peringer E, Lercher JA (2007). "Methyl chloride production from methane over lanthanum-based catalysts". J. Am. Chem. Soc. 129 (9): 2569–76. doi:10.1021/ja066913w. PMID 17295483.