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 Al(alloy) + AlCl3(gas) → 3 AlCl(gas)

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.