aluminum chloride

Short definition from Wiktionary

Noun

1. 1
   AlCl, only exists in the gas phase when AlCl₃ is heated with aluminium.
2. 2
   AlCl₃, the aluminium salt of hydrochloric acid; forms the covalent dimer Al₂Cl₆ when melted; it has very many industrial applications, including that of a catalyst in Friedel-Crafts reactions.