Aluminium borohydride
Encyclopedia
Aluminium borohydride, also known as aluminium tetrahydroborate, (in American English
, aluminum borohydride and aluminum tetrahydroborate, respectively) is the chemical compound with the formula
Al(BH4)3. It is a volatile pyrophoric liquid which is used as rocket fuel or jet fuel
, or as a reducing agent
in laboratories. Unlike most other metal–borohydrides, which are ionic structures
, aluminium borohydride is a covalent compound.
with aluminium chloride
:
or as the non-pyrophoric tetrahydrofuran
(THF) adduct, by the analogous reaction of calcium borohydride and aluminium chloride
in THF:
gas, and reduces carboxylic esters, aldehyde
s, and ketone
s to alcohol
s.
American English
American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....
, aluminum borohydride and aluminum tetrahydroborate, respectively) is the chemical compound with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
Al(BH4)3. It is a volatile pyrophoric liquid which is used as rocket fuel or jet fuel
Jet fuel
Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardized international specification...
, or as a reducing agent
Reducing agent
A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...
in laboratories. Unlike most other metal–borohydrides, which are ionic structures
Ionic compound
In chemistry, an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually, the positively charged portion consists of metal cations and the negatively charged portion is an anion or polyatomic ion. Ions in ionic compounds are held together...
, aluminium borohydride is a covalent compound.
Preparation
Aluminium borohydride is formed by the reaction between sodium borohydrideSodium borohydride
Sodium borohydride, also known as sodium tetrahydridoborate, is an inorganic compound with the formula NaBH4. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a technical scale. Large amounts are...
with aluminium chloride
Aluminium chloride
Aluminium chloride is the main compound of aluminium and chlorine. It is white, but samples are often contaminated with iron trichloride, giving it a yellow colour. The solid has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large...
:
- 3 NaBH4 + AlCl3 → Al(BH4)3 + 3 NaCl
or as the non-pyrophoric tetrahydrofuran
Tetrahydrofuran
Tetrahydrofuran is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. This heterocyclic compound has the chemical formula 4O. As one of the most polar ethers with a wide liquid range, it is a useful solvent. Its main use, however, is as a precursor...
(THF) adduct, by the analogous reaction of calcium borohydride and aluminium chloride
Aluminium chloride
Aluminium chloride is the main compound of aluminium and chlorine. It is white, but samples are often contaminated with iron trichloride, giving it a yellow colour. The solid has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large...
in THF:
- 3 Ca(BH4)2 + 2 AlCl3 → 3 CaCl2 + 2 Al(BH4)3
Reactions
Like all borohydrides, this compound is a reducing agent and hydride donor. It reacts with water to give elemental hydrogenHydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
gas, and reduces carboxylic esters, aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
s, and ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
s to alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s.