Perfluoroalkyl carboxylic acids

Perfluoroalkyl carboxylic acids (PFCAs), or perfluorocarboxylic acids are compounds of the formula CnF(2n+1)CO2H that belong to the class of per- and polyfluoroalkyl substances.

These compounds are organofluorine analogues of ordinary carboxylic acids, but they are stronger by several pKa units and they exhibit great hydrophobic character.

Longer-chain perfluoroalkyl carboxylic acids, e.g. with five to nine carbons, are useful fluorosurfactants and emulsifiers used in the production of polytetrafluoroethylene (Teflon) and related fluoropolymers.

[1] These compounds are typically prepared by electrochemical fluorination of the carboxylic acid fluorides followed by hydrolysis: Long-chain PFCAs such as perfluorooctanoic acid (PFOA) are either banned or being under scrutiny because they are extremely persistent and bioaccumulative.

Short-chain PFCAs (scPFCAs) are formed from atmospheric oxidation of fluorotelomer compounds and chlorofluorocarbon (CFC) replacements introduced as a result of the Montreal Protocol.

Perfluorononanoic acid , an example of a perfluoroalkyl carboxylic acid (PFCA)
Simplified degradation pathway of urethane side-chain fluorinated polymers: hydrolysis yields fluorotelomer alcohols that are then degraded to PFCAs of different chain lengths (in the shown example PFHxA , PFHpA and PFBA ).