Lithium perchlorate

Lithium perchlorate
The orthorhombic unit cell of lithium perchlorate under standard conditions.
Unit cell of lithium perchlorate.
Names
IUPAC name
Lithium perchlorate
Other names
Perchloric acid, lithium salt; Lithium Cloricum
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.307
UNII
Properties
LiClO
4
Appearance white crystals
Odor odorless
Density 2.42 g/cm3
Melting point 236 °C (457 °F; 509 K)
Boiling point 430 °C (806 °F; 703 K)
decomposes from 400 °C
42.7 g/100 mL (0 °C)
49 g/100 mL (10 °C)
59.8 g/100 mL (25 °C)
71.8 g/100 mL (40 °C)
119.5 g/100 mL (80 °C)
300 g/100 g (120 °C)[1]
Solubility soluble in alcohol, ethyl acetate[1]
Solubility in acetone 137 g/100 g[1]
Solubility in alcohol 1.82 g/g (0 °C, in CH3OH)
1.52 g/g (0 °C, in C2H5OH)
1.05 g/g (25 °C, in C3H7OH)
0.793 g/g (0 °C, in C4H9OH)[1]
Structure
Pnma, No. 62
a = 865.7(1) pm, b = 691.29(9) pm, c = 483.23(6) pm[2]
4 formula per cell
tetrahedral at Cl
Thermochemistry
105 J/mol·K[1]
125.5 J/mol·K[1]
-380.99 kJ/mol
-254 kJ/mol[1]
Hazards
Main hazards Oxidizer, irritant
Safety data sheet MSDS
GHS pictograms [3]
GHS signal word Danger
H272, H315, H319, H335[3]
P220, P261, P305+351+338[3]
NFPA 704
Related compounds
Other anions
 Lithium chloride
Lithium hypochlorite
Lithium chlorate
Other cations
 Sodium perchlorate
Potassium perchlorate
Rubidium perchlorate
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

Lithium perchlorate is the inorganic compound with the formula LiClO4. This white or colourless crystalline salt is noteworthy for its high solubility in many solvents. It exists both in anhydrous form and as a trihydrate.

Applications

Inorganic chemistry

Lithium perchlorate is used as a source of oxygen in some chemical oxygen generators. It decomposes at about 400 °C, yielding lithium chloride and oxygen:[4]

LiClO4 → LiCl + 2 O2

Over 60% of the mass of the lithium perchlorate is released as oxygen. It has both the highest oxygen to weight and oxygen to volume ratio of all practical perchlorate salts.

Organic chemistry

LiClO4 is highly soluble in organic solvents, even diethyl ether. Such solutions are employed in Diels-Alder reactions, where it is proposed that the Lewis acidic Li+ binds to Lewis basic sites on the dienophile, thereby accelerating the reaction.[5]

Lithium perchlorate is also used as a co-catalyst in the coupling of α,β-unsaturated carbonyls with aldehydes, also known as the Baylis-Hillman reaction.[6]

Batteries

Lithium perchlorate is also used as an electrolyte in lithium-ion batteries. Lithium perchlorate is chosen over alternative electrolytes such as lithium hexafluorophosphate or lithium tetrafluoroborate when its superior electrical impedance, conductivity, hygroscopicity, and anodic stability properties are of importance to the specific application.[7] However, these beneficial properties are often overshadowed by the electrolyte's strong oxidizing properties, making the electrolyte reactive toward its solvent at high temperatures and/or high current loads. Due to these hazards the battery is often considered unfit for industrial applications.[7]

Biochemistry

Concentrated solutions of lithium perchlorate (4.5 mol/L) are used as a chaotropic agent to denature proteins.

Production

Lithium perchlorate can be manufactured by reaction of sodium perchlorate with lithium chloride. It can be also prepared by electrolysis of lithium chlorate at 200 mA/cm² at temperatures above 20 °C.[8]

Safety

Perchlorates often give explosive mixtures with organic compounds.[8]

References

  1. 1 2 3 4 5 6 7 http://chemister.ru/Database/properties-en.php?dbid=1&id=612
  2. ↑ doi:10.1002/zaac.200300114
  3. 1 2 3 Sigma-Aldrich Co., Lithium perchlorate. Retrieved on 2014-05-09.
  4. ↑ M. M. Markowitz, D. A. Boryta, and Harvey Stewart, Jr. (1964). "Lithium Perchlorate Oxygen Candle. Pyrochemical Source of Pure Oxygen". Ind. Eng. Chem. Prod. Res. Dev. 3: 321–330. doi:10.1021/i360012a016.
  5. ↑ Charette, A. B. "Lithium Perchlorate" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
  6. ↑ Lithium Perchlorate Product Detail Page
  7. 1 2 Xu, Kang (2004). "Nonaqueous liquid electrolytes for lithium-based rechargeable batteries" (PDF). Chemical Reviews. 104 (10): 4303–4417. doi:10.1021/cr030203g. PMID 15669157. Retrieved 24 February 2014.
  8. 1 2 Helmut Vogt, Jan Balej, John E. Bennett, Peter Wintzer, Saeed Akbar Sheikh, Patrizio Gallone "Chlorine Oxides and Chlorine Oxygen Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH. doi:10.1002/14356007.a06_483
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