Aluminium borohydride explained

Aluminium borohydride, also known as aluminium tetrahydroborate, is the chemical compound with the formula Al(BH₄)₃. It is a volatile pyrophoric liquid which is used as a reducing agent in laboratories. Unlike most other metal–borohydrides, which are ionic structures, aluminium borohydride is a covalent compound.^[1]

Preparation

Aluminium borohydride is formed by the reaction between sodium borohydride with aluminium chloride:^[2]

3 NaBH₄ + AlCl₃ → Al(BH₄)₃ + 3 NaCl

or as the non-pyrophoric tetrahydrofuran (THF) adduct, by the analogous reaction of calcium borohydride and aluminium chloride in THF:^[3]

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 hydrogen gas,^[2] and reduces carboxylic esters, aldehydes, and ketones to alcohols.^[3]

Further reading

• 10.1021/ie50599a044 . Aluminum Borohydride and Mixtures with Hydrocarbons in Jet Engine Combustor Ignition . 1959 . Fletcher . Edward . Foster . Hampton . Straight . David . Industrial & Engineering Chemistry . 51 . 1389 . 11.
• 10.1021/ie50548a032 . Aluminum Borohydride Preparation . 1955 . Hinkamp . James B. . Hnizda . Vincent . Industrial & Engineering Chemistry . 47 . 1560 . 8.

Notes and References

1. . 2007. 446–447 . 310–314 . 10.1016/j.jallcom.2006.11.140 . K. . Miwa . N. . Ohba . S. . Towata . Y. . Nakamori . A. . Züttel . S.. Orimo . First-principles study on thermodynamical stability of metal borohydrides: Aluminum borohydride Al(BH₄)₃ . cond-mat/0610853 . 97032806.
2. Book: Perry. Dale L.. Phillips. Sidney L.. 1995. Handbook of Inorganic Compounds. CRC Press. 0-8493-8671-3. 3–4. 2007-12-09.
3. J. Kollonitsch & O. Fuchs . Preparation of Aluminium Borohydride and its Applications in Organic Reductions . . 176 . 1081 . 1955 . 10.1038/1761081a0 . 4492. 1955Natur.176.1081K . free .