Thermal and photolytic stabilities of perfluoroalkane sulfonic acids and their derivatives

The use of perfluoroalkanesulfonic acids and their derivatives in drastic conditions leads us to study their behaviour with respect to temperature and radiative factors.Such acids as CF₃SO₃H and C₂F₅SO₃H, used in a pure state as well as their related pure anhydride are stable until they reach a temperature of at least 180°C.On the other hand, the solutions of anhydride with its related acid, yield perfluorosulfonic esters and SO₂ at room temperature already:

This mechanism is discussed.These results involve a new and easy synthesis of symmetrical perfluorosulfonic esters R_FSO₃R_F with acids and P₂O₅.

Further more, it occurs no transformation of the anhydride under UV and visible irradiation. But under the same conditions, a small account of acids are deshydrated into anhydrides.A further experiment combining both effects of temperature and light leads to the esters.