Carbon Dioxide → 6-(1,2,2,2-Tetrafluoroethoxy)perfluorohexanoic acid

Participants

Reaction Steps

A sample of diacid fluoride, FCOCF(CF3)—O—(CF2)5COF (500 g, 1.1 mol) prepared from the hexafluoropropylene oxide (HFPO) coupling of perfluoroadipoyl fluoride as described in U.S. Pub. No. US 2004/0116742 and was added over 2 hours to a stirred slurry of sodium carbonate (500 g, 4.7 mol) in 500 g of diglyme at 85° C. to make the disalt. The reaction liberated CO2 gas. Distilled water (25 g, 1.4 mol) was added at 85° C. The mixture was heated up to 168° C. with CO2 off-gassing and held for 30 minutes. Reaction was cooled down and sulphuric acid (350 g, 3.6 mol) in 1100 g of water was added to make the reaction mixture acidic. Bottom phase was washed with 400 g of 50% sulfuric acid and vacuum distilled to give CF3—CFH—O—(CF2)5COOH 426 g, 1.0 mol for a 95% yield having a boiling point of 132-135° C./15 mm. This was followed by the addition of 46 g NaOH in 63 g of water. Dried salts in vacuum oven at 112° C./15 mm Hg to give 386 g of slight yellow sticky solids. To the salt was added sulphuric acid and the lower fluorochemical phase was vacuum distilled. The previous process was repeated two more times to yield a colorless acid. The surfactant CF3—CFH—O—(CF2)5COONH4 having a melting point of 159-165° C. was made quantitatively from the reaction of 200 g of acid reacted with excess ammonium hydroxide and dried.

Provenance & Evidence