The Hammett Acidity Function H₀ of Trifluoromethanesulfonic Acid-Trifluoroacetic Acid and Related Acid Systems. A Versatile Nonaqueous Acid System

Abstract

The acidity function (H₀) of mixtures of trifluoromethanesulfonic acid (TFSA) and trifluoroacetic acid (TFA) was measured. Nonaqueous acid systems based on TFSA, which is distillable, stable, non-oxidative and only weakly nucleophilic, can cover a wide range of acidity comparable to that of aqueous sulfuric acid, and should be useful for mechanistic and synthetic studies in organic chemistry. An H₀ value lower than-16 could be obtained by adding a small amount of SbF₅ to TFSA.