Chem. J. Chinese Universities ›› 1998, Vol. 19 ›› Issue (6): 890.

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The ESR Spin Trapping Studies of Reaction Between Ascorbic Acid with Hydrogen Peroxide

BAI Ling-Jun, WANG Jian-Ying   

  1. Department of Chemistry, Nankai University, Tianjin, 300071
  • Received:1997-05-10 Online:1998-06-24 Published:1998-06-24

Abstract: Using 5,5-dimethyl-1-pyrroline N-oxide(DMPO) as a spin-trapping reagent, the oxidation reaction of ascorbic acid was studied. The radical generated in autoxidation process was ascorbate radical anion(A-·) only. In the presence of hydrogen peroxide, several radical intermediates were found and their structure were determined. The ESR parameters of A-· and DMPO/radical adducts were measured to be g =2.0056 and α H=0.17 mT for A-·, g =2.0059, αN=1.60 mT and αHβ=2.28 mT for DMPO/1, g =2.0059, αN=1.58 mT, αHβ=2.13 mT and αHγ=0.17 mT for DMPO/2, g =2.0059 and αN= αHβ=1.49 mT for DMPO/·OH, and g =2.0059 and αN=1.50 mT for DMPO/3(or 4). The mechanisms for the oxidation reactions of ascorbic acid were proposed on the basis of those observation.

Key words: Ascorbic acid, ESR-spin trapping, Hydrogen peroxide, Ascorbate radical anion

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