A new method for recovering waste alkaline perfluoro-n-butanesulfonate

A new method for recovering perfluoro-n-butanesulfonic acid from its waste alkaline salts and re-converting it into the corresponding 2,2,2-trifluoroethyl ester alkylating agent is described. Alkaline perfluoro-n-butanesulfonate can be converted into the corresponding acid by treating it with gaseous HCl in methanol; perfluoro-n-butanesulfonic acid is then directly esterified by treatment with 2,2,2-trifluoroethanol in thionyl chloride. Easy procedures and high yields could make this method important for industrial application, with possible economic and environmental benefits.