lanthanum(III) Chloride
Properties
| State | Solid (hygroscopic; commonly hydrated) |
| Color | white to colorless |
| Solubility | Very soluble in water; soluble in alcohols |
| Melting Point | 894 °C (anhydrous) |
About lanthanum(III) Chloride
Lanthanum(III) chloride is the entry-point reagent for almost any solution-phase work with the rare-earth ion La(III) — but the catch is that the form you can actually buy is almost always the heptahydrate LaCl3·7H2O (or hexahydrate), not the anhydrous solid. Try to dehydrate the hydrate by heating in air and you'll get LaOCl plus HCl gas, not the chloride: La-O bonds are too strong to peel off the last waters cleanly. Anhydrous LaCl3 has to be made the hard way — vacuum sublimation at 850°C, or heating the hydrate with NH4Cl under argon so the ammonium chloride scavenges the water before La-O bonds can form. In the crystal, La3+ sits in a 9-coordinate tricapped trigonal prism, the typical geometry for the early lanthanides where the ionic radius is large enough to fit nine ligands without strain. In synthesis, LaCl3 functions as a mild oxophilic Lewis acid: the classic Luche reduction (NaBH4 + LaCl3 in methanol) is normally written with CeCl3 but LaCl3 works almost identically for the selective 1,2-reduction of α,β-unsaturated ketones to allylic alcohols without 1,4-attack. Outside synthesis, La3+ is a textbook non-specific blocker of voltage-gated calcium channels in patch-clamp electrophysiology — IC50 in the sub-micromolar range — useful when a researcher needs to confirm whether a current is Ca2+-mediated. It's also the feedstock for electrolytic production of lanthanum metal from molten LaCl3-KCl baths.
Where you'll encounter it
If you've ever read a paper using a 'Luche reduction' on a chalcone or run a patch-clamp protocol with La3+ to silence Ca2+ currents in a hippocampal slice, you've probably been looking at LaCl3 in the methods section. Synthetic chemists running the Luche reduction on alpha,beta-unsaturated ketones add LaCl3 (or its CeCl3 cousin) to NaBH4 in methanol to selectively reduce the carbonyl to the allylic alcohol without 1,4-conjugate-addition byproducts — a classic trick written into hundreds of total syntheses. Electrophysiologists working with hippocampal or cortical brain slices dose 100-300 nM La3+ from LaCl3 stock to block voltage-gated Ca2+ channels and confirm whether a recorded current depends on calcium influx. Refineries also pull LaCl3 into FCC catalyst manufacture as the alternate ion-exchange precursor when sulfate or nitrate side chemistry is unwanted.
Common Uses
- Luche-type 1,2-selective reduction of enones with NaBH4 in methanol
- Non-specific Ca2+-channel blocker in patch-clamp electrophysiology at sub-µM
- Electrolyte component in molten-salt production of lanthanum metal
- Catalyst for petroleum-cracking zeolite-Y exchange (La-stabilized FCC)
- Phosphor host material precursor in fluorescent-lamp manufacture
- NMR shift reagent precursor in lanthanide-induced shift studies
- Doping precursor for laser-crystal growth (Ce:LaBr3 scintillators)
Safety Information
GHS classifications: H315 (skin irritation Cat 2), H319 (eye irritation Cat 2A), H335 (respiratory irritation). Hydrates release HCl on contact with strong acids or on heating. Acute oral LD50 in rats around 4180 mg/kg — moderate toxicity. No OSHA PEL specifically for lanthanum compounds; ACGIH lists no TLV but follow general dust limits of 10 mg/m3 (total) and 5 mg/m3 (respirable). Use nitrile gloves and dust mask for powder handling, especially when transferring from supplier bottles in unconditioned air.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.