Photolysis of fluorinated organic molecules: fluorine mass balances and the roles of nucleophiles, rings, and degree of fluorination

Organofluorine containing pharmaceuticals and pesticides are widely used resulting in their accumulation within the environment. When these chemicals are exposed to environmental conditions, abiotic degradation pathways such as photolysis may occur. Photolysis results from photon absorption by a chromophore on the molecule. Following photon absorption, chemical bond breakage, rearrangement, and product formation may occur. Indirect photolysis is a parallel process due to reactive species present within the system absorbing photons and forming photochemically produced reactive intermediates that then go on to react with the contaminant of interest. In this work fluorinated compounds were exposed to a variety of photolysis conditions. Reaction rates, quantum yields, and bimolecular rate constants were measured to gain an understanding of the reactivity of these compounds. 19F nuclear magnetic resonance spectroscopy was used to complete fluorine mass balances, to confirm the presence and identities of organofluorine degradation products, and to aid in predicting organofluorine degradation pathways. Fluoride was the major degradation product across all studies. While defluorination into inert fluoride is the ideal degradation result, a range of organofluorine products were formed. Fluoroacetic acids, acetamides, and products retaining the parent compound fluorinated motifs were observed. The results of these studies aid in understanding how organofluorine compounds will transform within the environment and guide future design of chemicals to limit the persistence of synthetic fluorinated functional groups in the environment.

Author dc:creator

• Mundhenke, Thomas

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/11299/278754

OAI identifier oai:identifier

oai:conservancy.umn.edu:11299/278754