Lithium borohydride
| Names | |
|---|---|
| IUPAC name
Lithium tetrahydridoborate
| |
| Other names
Lithium boron hydride
Lithium hydroborate Lithium tetrahydroborate | |
| Properties | |
| 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) |
| 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 (S |
75.7 J·mol-1K-1 |
| Std enthalpy of
formation (ΔfH |
-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.
Contents
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 gasoline.
Availability
It is sold by chemical suppliers.
Preparation
Lithium borohydride may be prepared by the metathesis reaction, which occurs upon ball-milling the more commonly available sodium borohydride, and lithium bromide:[1]
- NaBH4 + LiBr → NaBr + LiBH4
Alternatively it may be synthesized by treating lithium hydride with boron trifluoride in diethyl ether:[2]
- 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.
References
- ↑ Peter Rittmeyer, Ulrich Wietelmann “Hydrides” in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim.
- ↑ Brauer, Georg (1963). Handbook of Preparative Inorganic Chemistry Vol. 1, 2nd Ed. Newyork: Academic Press. p. 775. ISBN 978-0121266011.
Relevant Sciencemadness threads
- Articles containing unverified chemical infoboxes
- Chembox articles without image
- Chemical compounds
- Inorganic compounds
- Lithium compounds
- Boron compounds
- Hydrogen compounds
- Metal hydrides
- Borohydrides
- Reducing agents
- Desiccants
- Materials unstable in acidic solution
- Materials that react with water
- Irritants
- Air-sensitive materials
- Pyrophoric materials
