hexafluoroantimonic

Hexafluoroantimonic acid is a strong superacid composed of antimony, fluorine, and hydrogen, with the chemical formula HSbF₆. It is a colorless, highly corrosive liquid that exhibits exceptional acidity, surpassing that of even the strongest known mineral acids like perchloric acid. This property arises from its ability to fully dissociate in certain solvents, generating a high concentration of protons (H⁺ ions).

Hexafluoroantimonic acid is typically prepared by reacting antimony pentafluoride (SbF₅) with hydrogen fluoride (HF) in the presence of a proton source, such as hydrogen chloride (HCl) or sulfuric acid (H₂SO₄). The reaction produces the acid in situ, often as a solution in anhydrous hydrogen fluoride or other low-nucleophilicity solvents. Due to its extreme reactivity, it is rarely isolated in pure form and is usually handled as a solution.

The compound is notable for its use in superacid chemistry, where it serves as a catalyst or medium for reactions that would otherwise be impossible under conventional conditions. It has been employed in studies of carbocations, Friedel-Crafts alkylations, and other highly acidic environments. However, its handling requires extreme caution due to its corrosive nature and potential to react violently with water or other nucleophilic substances.

Hexafluoroantimonic acid is also used in the synthesis of other superacids, such as magic acid (a mixture of SbF₅ and HF), which further enhances its acidic strength. Its applications extend to specialized industrial processes, though its use is limited by safety concerns and the need for controlled environments. Research into its properties continues, particularly in fields requiring extreme acidity for catalytic or synthetic purposes.