2,3,5,6-Tetrafluoro-4-hydroxybenzoic acid (CAS number 652-34-6) is a perfluorinated para-hydroxybenzoic acid building block. Due to its perfluorination, 2,3,5,6-tetrafluoro-4-hydroxybenzoic acid is relatively acidic with an observed pKa of 5.3, compared to non-fluorinated 4-hydroxybenzoic acid (pKa of 9.3). 2,3,5,6-Tetrafluoro-4-hydroxybenzoic acid is a precursor used to synthesize BMV109 which serves as a fluorescent activity-based probe for bioimaging. This probe is intrinsically non-fluorescent but only becomes fluorescent after reacting with a target protease.
2,3,5,6-Tetrafluoro-4-hydroxybenzoic acid is also employed in the preparation of novel inhibitors for protein farnesyltransferase (FTase) and geranylgeranyltransferase (GGTase), through Mitsunobu reaction. Enzyme inhibition studies demonstrate a potency of 2.9 µM against FTase and 7.5 µM against GGTase.