Fluoroantimonic acid is an inorganic compound with the chemical formula H2FSbF6 (also written H2F[SbF6], 2HF·SbF5, or simply HF-SbF5). It is an ionic liquid produced by treating hydrogen fluoride (HF) with antimony pentafluoride (SbF5) in a stoichiometric ratio of 2:1. It is the strongest superacid. It is particularly corrosive and toxic. It has been shown to protonate even hydrocarbons to afford pentacoordinate carbocations. Similar acids can be created by using excess antimony pentafluoride.
The reaction to produce fluoroantimonic acid is:
SbF5 + 2 HF → SbF−6 + H2F+
The acid is often said to...