Perfluoropropionic acid explained

Perfluoropropionic acid (PFPrA) or pentafluoropropionic acid is an ultra-short chain perfluoroalkyl carboxylic acid with the formula CF₃CF₂CO₂H. It is a colorless liquid that is strongly acidic. It soluble in both water and polar organic solvents. The compound is produced by electrochemical fluorination of the carboxylic acid or its acid fluoride derivative.^[1]

It has a predicted pK_a of 0.38, with an uncertainty of 0.10.^[2] In many ways, it is comparable to trifluoroacetic acid.

Occurrence and use

The perfluoropropanoate form has been found in environmental samples.^[3]

A convenient laboratory method for generating tetrafluoroethylene is the pyrolysis of the sodium salt of pentafluoropropionic acid:^[4]

C₂F₅CO₂Na → C₂F₄ + CO₂ + NaF

References

1. Book: 10.1002/14356007.a11_349 . Fluorine Compounds, Organic . Ullmann's Encyclopedia of Industrial Chemistry . 2000 . Siegemund . Günter . Schwertfeger . Werner . Feiring . Andrew . Smart . Bruce . Behr . Fred . Vogel . Herward . McKusick . Blaine . 978-3-527-30385-4.
2. Web site: Perfluoropropionic acid 422-64-0 . 2024-02-03 . ChemicalBook . en.
3. Neuwald . Isabelle J. . Hübner . Daniel . Wiegand . Hanna L. . Valkov . Vassil . Borchers . Ulrich . Nödler . Karsten . Scheurer . Marco . Hale . Sarah E. . Arp . Hans Peter H. . Zahn . Daniel . Ultra-Short-Chain PFASs in the Sources of German Drinking Water: Prevalent, Overlooked, Difficult to Remove, and Unregulated . Environmental Science & Technology . 17 May 2022 . 56 . 10 . 6380–6390 . 10.1021/acs.est.1c07949 . 2022EnST...56.6380N . 11250/3069800 . free.
4. 10.1016/j.jfluchem.2016.10.004. Preparation of tetrafluoroethylene from the pyrolysis of pentafluoropropionate salts. 2017. Hercules. Daniel A.. Parrish. Cameron A.. Sayler. Todd S.. Tice. Kevin T.. Williams. Shane M.. Lowery. Lauren E.. Brady. Michael E.. Coward. Robert B.. Murphy. Justin A.. Hey. Trevyn A.. Scavuzzo. Anthony R.. Rummler. Lucy M.. Burns. Emory G.. Matsnev. Andrej V.. Fernandez. Richard E.. McMillen. Colin D.. Thrasher. Joseph S.. Journal of Fluorine Chemistry. 196. 107–116. free.