Sodium trifluoromethanesulfinate

Sodium trifluoromethanesulfinate (CF₃SO₂Na) is the sodium salt of trifluoromethanesulfinic acid. Together with t-butyl hydroperoxide, an oxidant, this compound was found to be a suitable reagent for introducing trifluoromethyl groups onto electron-rich aromatic compounds by Langlois; this reagent is also known as the Langlois reagent. This reaction operates via a free radical mechanism.

This reagent is also able to trifluoromethylate electron-deficient aromatic compounds under biphasic conditions. Zinc difluoromethanesulfinate, a related polymeric coordination complex, is able to introduce difluoromethyl groups (CHF₂-) onto aromatic compounds under similar biphasic conditions as well.