Lithium perchlorate

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.

Lithium perchlorate
Names

Li⁺Cl+7O−2 Unit cell of lithium perchlorate.
IUPAC name Lithium perchlorate
Other names Perchloric acid, lithium salt; Lithium Cloricum
Identifiers
CAS Number	7791-03-9^Y
3D model (JSmol)	Interactive image
ChemSpider	133514^Y
ECHA InfoCard	100.029.307
PubChem CID	23665649
UNII	Q86SE98C9C^N
CompTox Dashboard (EPA)	DTXSID40872829
InChI InChI=1S/ClHO4.Li/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1^Y Key: MHCFAGZWMAWTNR-UHFFFAOYSA-M^Y InChI=1/ClHO4.Li/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1 Key: MHCFAGZWMAWTNR-REWHXWOFAR
SMILES [Li+].[O-]Cl(=O)(=O)=O
Properties
Chemical formula	LiClO ₄
Molar mass	106.39 g/mol (anhydrous) 160.44 g/mol (trihydrate)
Appearance	White crystals
Odor	Odorless
Density	2.29 g/cm³ (20 °C (68 °F))
Melting point	236 °C (457 °F; 509 K)
Boiling point	430 °C (806 °F; 703 K) decomposes from 400 °C (752 °F)
Solubility in water	42.7 g/100 mL (0 °C (32 °F)) 49 g/100 mL (10 °C (50 °F)) 59.8 g/100 mL (25 °C (77 °F)) 71.8 g/100 mL (40 °C (104 °F)) 119.5 g/100 mL (80 °C (176 °F)) 300 g/100 mL (120 °C (248 °F))
Solubility	79.3 g/100 g 1-butanol 58 g/100 g isobutanol
Solubility in acetone	137 g/100 g
Solubility in methanol	182 g/100 g
Solubility in ethanol	152 g/100 g
Solubility in 1-propanol	105 g/100 g
Solubility in ethyl acetate	95.2 g/100 g
Solubility in ethyl ether	113.7 g/100 g
Structure
Space group	Pnma, No. 62
Lattice constant	a = 865.7(1) pm, b = 691.29(9) pm, c = 483.23(6) pm
Formula units (Z)	4 formula per cell
Coordination geometry	tetrahedral at Cl
Thermochemistry
Heat capacity (C)	105 J/mol⋅K
Std molar entropy (S^⦵₂₉₈)	125.5 J/mol⋅K
Std enthalpy of formation (Δ_fH^⦵₂₉₈)	−380.99 kJ/mol
Gibbs free energy (Δ_fG^⦵)	−254 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Oxidizer, irritant
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H272, H315, H319, H335
Precautionary statements	P210, P220, P221, P260, P264, P270, P271, P280, P301+P312+P330, P301+P330+P331, P303+P361+P353, P304+P340+P310, P305+P351+P338+P310, P363, P370+P378, P403+P233, P405, P501
NFPA 704 (fire diamond)	1 0 0 OX
Lethal dose or concentration (LD, LC):
LD₅₀ (median dose)	1150+850 −850 mg/kg (Oral - Rat - Female)
Safety data sheet (SDS)	MSDS
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). N verify (what is ^YN ?) Infobox references

Applications

Inorganic chemistry

Lithium perchlorate is used as a source of oxygen in some chemical oxygen generators. It decomposes at about 400 °C (752 °F), yielding lithium chloride and oxygen:

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, and higher oxygen to volume ratio than liquid oxygen.

Lithium perchlorate is used as an oxidizer in some experimental (as of 1975) solid rocket propellants, and rarely to produce red colored flame in pyrotechnic compositions.

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.^{[page needed]}

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.

Solid lithium perchlorate is found to be a mild and efficient Lewis acid for promoting cyanosilylation of carbonyl compounds under neutral conditions.

Batteries

Lithium perchlorate is also used as an electrolyte salt in lithium-ion batteries. Lithium perchlorate is chosen over alternative salts 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. 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.

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 (68 °F).

Safety

Perchlorates often give explosive mixtures with organic compounds, finely divided metals, sulfur, and other reducing agents.