Synthesis of fluorinated phosphonic, sulfonic, and mixed phosphonic/sulfonic acids

Abstract

The acids (HO) 2 P(O)CFHSO 3 H, (HO) 2 P(O)(CF 2 ) 4 O(CF 2 ) 2 SO 3 H, H(CF 2 ) 2 O(CF 2 ) 2 P(O)(OH) 2 , H(CF 2 ) 2 O(CF 2 ) 4 P(O)(OH) 2 , (HO) 2 P(O)(CF 2 ) 2 O(CF 2 ) 4 H, and the acid precursor (C 2 H 5 O) 2 P(O)CF(SO 3 Na) 2 have been synthesized. Elemental analysis, 19 F, 1 H, and 31 P NMR, and mass spectroscopy were used for characterization of these materials. They are very strong acids, and exhibit a high degree of stability in aqueous solution at elevated temperature, which makes them attractive candidates for use as electrolytes in fuel cells. Keywords: fluorinated phosphonic acids; fluorinated sulfonic acids; 1 H, 19 F, 31 P NMR.