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.
Alcan process When an aluminium 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.
It then disproportionates into aluminium melt and aluminium trichloride upon cooling to 900 °C.
The process is an instance of the general sub-halide catalytic distillation method (subhalide process) developed by Philipp Gross. It was sold to Alcan but never put into full-scale production.
Interstellar medium 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
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