The synthesis and some chemistry of 2-ketopentafluoropropanesulfonic acid (1) are described. In particular, reactions at the carbonyl group of 1 found to proceed with ease were acid-catalyzed condensations and free-radical additions. The latter reaction was adapted to vinyl copolymerizations of 1 with CFz= CF2 and with CFz= CH2 to prepare new sulfonated fluoro polymers. Both the copolymer of 1 with CFz= CF2 and Nafion, a ...