Design, synthesis, and calibration of peroxyl-radical clocks for the determination of kinh's of antioxidants and kp's of hydrocarbons

Abstract

The projects described herein show the effect of double bond geometry on the ƒÒ-fragmentation of biologically relevant methyl octadecadienoate peroxyl radicals and analogous pentadecadiene peroxyl radicals. From these experiments, two new peroxyl radical clocks were developed. The allylbenzene peroxyl radical clock was designed to determine rate constants of hydrogen atom donors occurring between 104 and 106 M-1s-1, while the conjugated methyl linoleate clock was designed to determine rate constants of hydrogen atom donors between 100 and 104 M-1s-1. The rate constants (kinh) of many commercially useful antioxidants can be determined with relative ease and with the use of general instrumentation found in an organic chemistry lab. Allylbenzene derivatives were also used to offer insight into the mechanism of the allylperoxyl radical rearrangement, a biologically important process in the general oxidation of biomolecules.