Fluorine has been incorporated within pharmaceuticals at a steadily increasing rate. The addition of a fluorine motif can alter the physiochemical properties of a molecule making the pharmaceutical more useful or effective. The introduction of a strong carbon-fluorine bond can increase metabolic and thermal stability, alter pKa values, increase lipophilicity and polarity, and increase membrane permeability among other affects. With the potential of pharmaceuticals to enter the environment and water systems, it becomes of concern what possible fluorinated degradation products may be created via the pathway of photolysis. The aims of this research are to identify and quantify fluorinated photolysis byproducts of pharmaceuticals with varying motifs. To understand how each motif impacts photolysis, the fluorinated pharmaceuticals are subjected to aqueous photodegradation at pH 5, 7, and 10, as well as conditions generating hydroxyl radial or hydrated electrons using a mercury vapor lamp. Degradation kinetics are quantified via HPLC and first order degradation. 19F-NMR is being used for quantification of fluorinated reaction products. LC-MS coupled with 19F-NMR is used for compound identification. Results indicate that aromatic CF3 groups have the ability to form trifluoroacetic acid (TFA) and fluoride. Heterocyclic CF3 groups tend to be retained with possible structural alterations other than the fluorine motifs. While 19F-NMR is useful for the quantification of fluorine degradation, it must be coupled with HPLC and LC-MS to determine degradation structures due to it only reporting on the chemical environment surrounding the fluorine atoms. These results are of importance because they will give insight into pharmaceutical drug design and how these various motifs may behave within waste water treatment processes and the environment.

Photoproduct formation, determination, and quantification of the photolysis of fluorinated pharmaceuticals

ACS Spring 2022

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