Lithium Chloride
Properties
| State | Solid at room temperature |
| Color | White crystalline powder (hygroscopic) |
| Solubility | Very soluble in water (84.5 g/100 mL at 20 °C) |
| Melting Point | 605 °C |
| Boiling Point | 1382 °C |
About Lithium Chloride
Lithium chloride looks like a boring alkali halide on paper but behaves nothing like NaCl or KCl in practice. The Li+ ion has an ionic radius of just 76 pm, giving it the highest charge density of any group 1 cation, and that translates directly into LiCl's two defining quirks: extreme hygroscopicity and unusual solubility in non-aqueous solvents. A bottle of LiCl left uncapped on the bench will deliquesce into a clear syrup within hours by pulling moisture out of the air — a 30% w/w LiCl solution maintains 24% relative humidity at equilibrium, which is why LiCl brines are the working fluid in absorption-cycle dehumidifiers and HVAC desiccant wheels in commercial buildings. Unlike NaCl (insoluble in alcohols), LiCl dissolves freely in methanol, ethanol, acetone, pyridine, and even certain ethers because the small Li+ forms strong ion-dipole interactions with polar organic solvents. That property is what lets LiCl/DMAc dissolve cellulose without derivatization, the basis for the Lyocell process for making Tencel fibers. Industrially, the largest single use is as the molten-salt electrolyte (with KCl, mp 352 °C eutectic) in the Downs-style electrolysis cells that produce metallic lithium for battery anodes and aluminum-lithium aerospace alloys. Brazing fluxes for aluminum, air-conditioning desiccants, organic-synthesis additives that solubilize cellulose or modify Pd-catalyzed coupling selectivity all depend on the same small-cation chemistry.
Where you'll encounter it
If you've ever set up a humidity-controlled chamber for protein crystallography by sitting your trays over a saturated LiCl bath, or run a Mizoroki-Heck coupling with LiCl added to suppress beta-hydride elimination, you've used the lithium-cation polarizing-power tricks that make this salt useful. Crystallographers seeding 96-well sitting-drop trays exploit the LiCl saturated-salt 24% RH equilibrium to slow vapor diffusion and grow larger single crystals over days instead of hours. Pd-coupling chemists adding 1-2 equivalents of LiCl to a Heck reaction find that the chloride ligand reroutes the catalytic cycle to favor anti-Markovnikov regioselectivity by changing the active Pd species. Industrial Lyocell plants dissolving cellulose pulp in LiCl/DMAc skip the xanthate chemistry of the older viscose process entirely, which is the entire technical case for the Tencel fiber line.
Common Uses
- Molten LiCl/KCl electrolyte for electrolytic production of lithium metal
- LiCl/DMAc solvent system for cellulose dissolution (Lyocell/Tencel process)
- Saturated-salt humidity standard for calibrating hygrometers (24% RH at 20 °C)
- Desiccant brine in commercial dehumidification and absorption-cycle HVAC systems
- Brazing flux component for aluminum joining
- Additive in Pd-catalyzed Mizoroki-Heck and Stille couplings to modulate selectivity
- Source of Li+ for psychiatric research (in vitro studies; not clinical use)
- Pyrotechnic colorant producing crimson-red flame color in flares and signal fires
Safety Information
GHS: Acute Tox. 4 oral (H302), Eye Irrit. 2A (H319). Less toxic than the carbonate but still systemic — large oral doses produce the same lithium-toxicity syndrome (tremor, ataxia, renal injury) that limits psychiatric lithium dosing. OSHA does not list a specific PEL; dust handling under standard nuisance-particulate controls. Hygroscopic — store under desiccant or in a dry box. Historically used as a salt substitute in the 1940s and pulled from the market after fatal lithium intoxications in cardiac patients on low-sodium diets, an episode that ironically led to the discovery of lithium's mood-stabilizing properties.
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. We deliberately do not publish occupational exposure limits or other regulatory thresholds: those values are revised over time and differ between jurisdictions, so the only correct source is the current SDS and the regulations that apply where you work.