Quinone Hemiacetal Formation from Protocatechuic Acid during the DPPH Radical Scavenging Reaction

Abstract

  Protocatechuic acid was rapidly converted to protocatechuquinone 3-methyl hemiacetal and protocatechuquinone during the reaction with DPPH radical in methanol. The structure of the acetal was determined by comparing the NMR data with those of an authentic compound prepared by (diacetoxy)iodobenzene oxidation of protocatechuic acid.