Abstract
Aromatic ring hydroxylation of phenolic compounds proceeded selectively in a Cu 2+-ascorbic acid-O 2 system. In contrast to usual oxidation systems, unusual substituent effects were observed: electron-withdrawing groups accelerate and electron-donating groups retard the hydroxylation. Hydroxyl radicals generated by γ-radiolysis also converted phenols into catechols and hydroquinones. The close resemblance of these two systems led us to presume that the active intermediate in the Cu 2+-ascorbic acid-O 2 system is hydroxyl radical or an equivalent species. The unusual substituent effects were also observed in the hydroxylation of p-substituted phenol by microsomes, a cytochrome P-450-dependent reaction. These results imply that the Cu 2+-ascorbic acid-O 2 system is an effective biominietic oxidation system.
Published Version
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