Lithium borohydride

Lithium borohydride

Names
IUPAC name Lithium tetrahydridoborate
Other names Lithium boron hydride Lithium hydroborate Lithium tetrahydroborate
Properties
Chemical formula	LiBH4
Molar mass	21.784 g/mol
Appearance	White or grayish solid
Odor	Odorless
Density	0.666 g/cm3 (20 °C)
Melting point	268 °C (514 °F; 541 K)
Boiling point	380 °C (716 °F; 653 K) (decomposes)
Solubility in water	Reacts
Solubility	Reacts with alcohols, carboxylic acids, aldehydes, halocarbons, ketones Soluble in ethers Insoluble in cyclohexane, heptane, hexane, pentane, toluene, xylene
Solubility in 1,4-Dioxane	0.3 g/100 ml (18 °C)
Solubility in diethyl ether	1.32 g/100 ml (0 °C) 3.04973 g/100 ml (25 °C) 6.62228 g/100 ml (34 °C)
Solubility in dimethoxyethane	4.13892 g/100 ml (0 °C) 4.5746 g/100 ml (75 °C)
Solubility in dimethyl ether	1.6 g/100 ml (-45.2 °C)
Solubility in tetrahydrofuran	24.8989 g/100 ml (25 °C)
Vapor pressure	~0 mmHg
Thermochemistry
Std molar entropy (So298)	75.7 J·mol-1K-1
Std enthalpy of formation (ΔfHo298)	-198.83 kJ/mol
Hazards
Safety data sheet	Sigma-Aldrich
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	87.8 mg/kg (mouse, oral)
Related compounds
Related compounds	Sodium borohydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Lithium borohydride (LiBH₄) is a chemical compound widely used in organic synthesis as a reducing agent, often for esters.

Properties

Chemical

Lithium borohydride reacts with water to release hydrogen gas.

LiBH₄ + 4 H₂O → LiOH + B(OH)₃ + 4 H₂

Physical

Lithium borohydride is a white solid, which reacts with water and alcohols, but it's soluble in ethers.

Lithium borohydride has the highest energy density of all known chemical energy carriers, with a value of 65.2 MJ/kg or 43.4 MJ/l, higher than that gasoline.

Availability

Lithium borohydride is sold by chemical suppliers. Can be found on Alibaba.

Preparation

Lithium borohydride may be prepared by the metathesis reaction, which occurs upon ball-milling the more commonly available sodium borohydride, and lithium bromide:

NaBH₄ + LiBr → NaBr + LiBH₄

Alternatively it may be synthesized by treating lithium hydride with boron trifluoride in diethyl ether:

BF₃ + 4 LiH → LiBH₄ + 3 LiF

Projects

• Reducing agent
• Fuel cells

Handling

Safety

Lithium borohydride reacts with water and moisture, and may ignite in open air.

Storage

Lithium borohydride should be kept in closed bottles, under inert gas.

Disposal

Can be safely neutralized by adding it slowly in a large volume of alcohol or water.