Fluoroantimonic acid

Fluoroantimonic acid is a superacidic mixture of hydrogen fluoride and antimony pentafluoride. Its exceptional acidity comes from the mixture’s ability to stabilize protonated species through weakly coordinating ions.

Hydrogen fluoride: Hydrogen fluoride is a molecular compound of hydrogen and fluorine that forms strongly hydrogen-bonded liquids. It supplies the acidic component and solvent in the mixture.
Superacid: A superacid is an acid stronger than pure sulfuric acid under comparable acidity measures. Fluoroantimonic acid is a prominent example of this broader class.
Carborane acid: Carborane acids are strong acids whose bulky, weakly coordinating anions can leave reactive cations relatively undisturbed. They offer a less nucleophilic alternative for generating highly reactive cations.
Sulfuric acid: Sulfuric acid is a strong diprotic mineral acid with formula H₂SO₄. It is the conventional benchmark that superacids are defined as stronger than.
Antimony pentafluoride: Antimony pentafluoride is a strong Lewis acid composed of antimony and fluorine. It binds fluoride ions, promoting proton donation by hydrogen fluoride.
Hammett acidity function: The Hammett acidity function estimates the protonating power of highly concentrated and nonaqueous acids. It is used to compare acidity where the aqueous pH scale is unsuitable.
Protonation: Protonation is the addition of a proton to an atom, molecule, or ion. The mixture can protonate compounds that resist protonation by ordinary acids.
Magic acid: Magic acid is a superacid mixture of fluorosulfuric acid and antimony pentafluoride. It is another antimony-pentafluoride superacid, made with a different Brønsted acid.
Fluoride ion: The fluoride ion is the negatively charged monatomic ion of fluorine. Antimony pentafluoride sequesters fluoride into complex anions, making proton transfer more favorable.
pH: pH is a logarithmic measure of hydrogen-ion activity in aqueous solutions. Aqueous pH does not meaningfully describe this concentrated, nonaqueous superacid.

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