Aluminium monochloride

Aluminium monochloride, or chloridoaluminium is the metal halide with the formula AlCl. Aluminium monochloride as a molecule is thermodynamically stable at high temperature and low pressure only. This compound is produced as a step in the Alcan process to smelt aluminium from an aluminium-rich alloy. When the alloy is placed in a reactor that is heated to 1,300 °C and mixed with aluminium trichloride, a gas of aluminium monochloride is produced.

$2\mathrm{A}\mathrm{l}(\mathrm{a}\mathrm{l}\mathrm{l}\mathrm{o}\mathrm{y})+\mathrm{A}\mathrm{l}\mathrm{C}\mathrm{l}{\phantom{A}}_3(\mathrm{g}\mathrm{a}\mathrm{s})⟶3\mathrm{A}\mathrm{l}\mathrm{C}\mathrm{l}(\mathrm{g}\mathrm{a}\mathrm{s})$

It then disproportionates into aluminium melt and aluminium trichloride upon cooling to 900 °C.

This molecule has been detected in the interstellar medium, where molecules are so dilute that intermolecular collisions are unimportant.

See also

• Aluminium monofluoride
• Aluminium monobromide
• Aluminium monoiodide

References

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