Triflic acid

Ball-and-stick model of triflic acid showing atoms as colored balls. The white atom is hydrogen, the red atoms are oxygen, the yellow atom is sulfur, the black atom is carbon, and the yellow-green atoms are fluorine.

Triflic acid is a chemical compound related to sulfuric acid. Because it is a stronger acid than pure sulfuric acid, it is called a superacid. Triflic acid is one of the most used superacids, mostly as a catalyst. Salts of triflic acid are called triflates.

It is also known by the systematic name trifluoromethanesulfonic acid. The chemical formula of triflic acid is written CF₃SO₃H, but is also often abbreviated as TfOH, where Tf is the functional group CF₃SO₂−, called triflyl.

It is a sulfonic acid, meaning one of the pairs of hydrogen and oxygen atoms in sulfuric acid has been replaced with a carbon atom. In triflic acid, this carbon atom is connected to three fluorine atoms, which makes a functional group called trifluoromethyl.