Phenyl radicals are known to rapidly abstract hydrogens and add to double bonds; H-abstraction in particular is known to have biological significance. However, rate constants for H-abstraction by neutral phenyl radicals from biomolecules are largely unknown. The present research uses p-fluorophenyl radicals generated by the photolysis of fluorophenylazoisobutyronitrile (FPAIN), which allows for product yields to be measured using F-19 NMR. DFT calculations validate this method by showing very similar SOMOs for the unsubstituted phenyl radical and the p-fluorophenyl radical, as well as nearly identical Mulliken charges on the radical carbon. Reported rate constants for phenyl radical iodine abstraction from iodoarenes (iodobenzene and m-trifluoroiodobenzene) (kI = 1 x 108 M-1 s-1) were used as kinetic reference points for determining kH for hydrogen abstraction from fatty acid methyl esters (FAMEs) as models for organic lipids. Preliminary results for methyl linoleate show that kH = 8 x 107 M-1 s-1.

F-19 NMR determination of relative rate constants for hydrogen abstraction by p-fluorophenyl radicals from fatty acid methyl esters

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.