In organic chemistry, triflate (systematic name: trifluoromethanesulfonate), is a functional group with the formula R−OSO2CF3 and structure R−O−S(=O)2−CF3. The triflate group is often represented by −OTf, as opposed to −Tf, which is the triflyl group, R−SO2CF3. For example, n-butyl triflate can be written as CH3CH2CH2CH2OTf.
The corresponding triflate anion, CF3SO−3, is an extremely stable polyatomic ion; this comes from the fact that triflic acid (CF3SO3H) is a superacid; i.e. it is more acidic than pure sulfuric acid, already one of the strongest acids known.