Synthesis of 14C‐labeled perfluorooctanoic and perfluorodecanoic acids; purification of perfluorodecanoic acid

Perfluoro‐n‐octaboic acid (PFOA) and perfluoro‐n‐decanoic acid (PFDA), two widely used industrial products, have been synthesized with 14C‐labeling in the C‐1 position. The carboxyl labeled materials were prepared in 48% and 53% yield by carbonation of perfluoroheptyllithium and perfluorononyllithium at −100°C. An efficient chemical method for purification of PFDA was also developed. Treatment of commercial PFDA with refluxing potassium hydroxide solution resulted in removal of the mono and diprotio impurities to give 99% pure PFDA.