Phenols are important in biological chemistry due to their antioxidant properties. A set of 2,6-di-t-butylated phenols with varying heterocyclic rings at their para positions were synthesized using palladium and copper coupling chemistry. The crystal structures of the phenols revealed an interesting hydrogen-bonding pattern involving the nominally quite hindered phenolic OH with heterocycle nitrogen acceptors. FTIR spectra helped to differentiate apparent H-bonds from intermolecular close contacts that involve OH groups. ESR spectra of the corresponding phenoxyl radicals were examined to establish the degree of unpaired electron delocalization (an indicator of potential reactivity). UV kinetic studies were carried out to compare the stabilities of the phenoxyl radicals. Apparently minor variation in the point of connection in azaheterocyclic rings to the hindered phenoxyl groups makes significant changes in relative radical stability.
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