Pentafluorophenol

Pentafluorophenol is an organofluorine compound consisting of a phenolic ring in which five hydrogen atoms are replaced by fluorine atoms, leaving a single hydroxyl group. Its chemical formula is C6HF5O. It is typically a colorless to pale liquid that is soluble in many organic solvents and has limited solubility in water. The compound behaves as a moderately strong acid for an aromatic alcohol; its conjugate base, the pentafluorophenoxide anion, is stabilized by the electron-withdrawing fluorine substituents. In water, its pKa is about 5.5, making it considerably more acidic than phenol.

Pentafluorophenol is used mainly as a precursor to pentafluorophenyl esters, which are highly activated carboxylating agents in organic synthesis and bioconjugation. These esters are commonly employed to activate carboxylic acids for amide and ester formation, including peptide bond formation. The fluorinated phenol can also serve as a leaving group in various substitution reactions and is encountered in the synthesis of pharmaceuticals and agrochemicals.

Safety and handling: Pentafluorophenol is corrosive and may cause skin and eye irritation. Vapors can be harmful if inhaled, and exposures should be minimized. It should be handled under proper ventilation with protective equipment, and waste disposed as hazardous fluorinated organic material under applicable regulations. Environmental concerns include persistence and potential toxicity of fluorinated aromatics.

Synthesis and availability: It can be prepared by fluorination of suitably substituted phenols or by conversion of pentafluorinated arenes to the phenol, and it is available from specialty chemical suppliers.