Triflic acid

Triflic acid, or trifluoromethanesulfonic acid, is a strong, non-oxidizing Brønsted acid with formula CF₃SO₃H. Its weakly coordinating conjugate base makes it useful in acid catalysis and synthesis.

Triflate: The trifluoromethanesulfonate anion, CF₃SO₃⁻, formed when triflic acid loses a proton. This conjugate base stabilizes charge while interfering relatively little with reactive cations.
Acid catalysis: Reaction acceleration through proton donation or other acid-mediated activation. Triflic acid activates substrates without serving as a stoichiometric oxidant.
Sulfonic acid: An organic acid containing the functional group R–SO₃H. Triflic acid is the exceptionally strong perfluorinated member of this acid family.
Sulfuric acid: A strong diprotic mineral acid with formula H₂SO₄ and substantial dehydrating properties. Triflic acid can be stronger while avoiding sulfuric acid’s characteristic dehydrating behavior.
Brønsted–Lowry acid–base theory: A theory defining acids as proton donors and bases as proton acceptors. Triflic acid catalyzes reactions by donating protons to substrates.
Friedel–Crafts reaction: An electrophilic aromatic substitution that installs alkyl or acyl groups on aromatic rings. Triflic acid can promote these reactions by generating or activating electrophiles.
Trifluoromethyl group: The –CF₃ substituent, in which three fluorine atoms replace hydrogen on a carbon group. This group strongly withdraws electron density from triflic acid’s sulfonic acid center.
Hydrochloric acid: A strong aqueous acid formed by hydrogen chloride dissolved in water. Its chloride conjugate base is more nucleophilic than triflate in many reactions.
Superacid: An acid stronger than pure sulfuric acid by the Hammett acidity scale. Triflic acid can reach superacidic strength in suitable media or mixtures.
Esterification: A reaction that forms an ester, commonly from a carboxylic acid and an alcohol. Triflic acid can catalyze ester formation by activating carbonyl groups.

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Carborane acidCompared with: Triflic acid is a familiar strong acid, but is substantially less acidic than the strongest carborane acids.