Generation of hydrogen peroxide and hydroxyl radical resulting from oxygen-dependent oxidation of L-ascorbic acid via copper redox-catalyzed reactions
研究了氧气与铜作为催化剂氧化L-抗坏血酸（L-AA）过程中过氧化氢（H2O2）和羟基自由基（HO）的产生，建立了O2 / Cu / L-AA工艺。苯甲酸（BA）作为探针试剂。产生的高浓度H 2 O 2经历分子内双电子转移并进一步被中间亚铜铜[Cu（I）]活化以产生HO 2作为产物，导致BA的显着降解。脱氢抗坏血酸，2,3-二酮古洛糖酸和L-木糖酮是L-AA氧化的主要检测产物。然而，H2O2的产生和BA的降解受pH的变化调节，这是由于质子化的L-AA与Cu（II）难以通过电子转移和氢离子（H +）螯合而产生的，这是必不可少的。用于产生H2O2。此外，随着L-AA剂量的增加，H2O2的浓度和BA的降解增加。痕量的Cu（II）对催化L-AA的氧化是有效的，而随着Cu（II）用量的增加，H2O2的产生和BA的降解增加。由于氯化铜（I）络合物或氯化铜（II）络合物的形成，氯化物（Cl-）的加入可以抑制H2O2的产生和BA的降解。
The generation of hydrogen peroxide (H2O2) and hydroxyl radical (HO˙) during the oxidation of L-ascorbic acid (L-AA) by oxygen with copper as a catalyst was investigated to set up the O2/Cu/L-AA process with benzoic acid (BA) as a probe reagent. The high concentration of H2O2 that is generated undergoes an intramolecular two-electron transfer and is further activated by the intermediate cuprous copper [Cu(I)] to yield HO˙ as a product, resulting in significant degradation of BA. Dehydroascorbic acid, 2,3-diketogulonic acid, and L-xylosone were the predominant detected products of the oxidation of L-AA. However, the generation of H2O2 and degradation of BA were regulated by variations in pH, which results from the contradiction between protonated L-AA that is difficult to chelate with Cu(II) via electron transfer and hydrogen ions (H+), which are indispensable for the generation of H2O2. Furthermore, the concentration of H2O2 and degradation of BA increased with an increase in the dosage of L-AA. Trace amounts of Cu(II) are effective for catalyzing the oxidation of L-AA, whereas the generation of H2O2 and degradation of BA increased with an increase in the dosage of Cu(II). Owing to the formation of Cu(I) chloride complexes or Cu(II) chloride complexes, the addition of chloride (Cl−) could inhibit the generation of H2O2 and degradation of BA.
Peng Zhou,a Jing Zhang,*a Yongli Zhang,a Ya Liu,a Juan Liang,a Bei Liua and Wei Zhanga
Generation of hydrogen peroxide and hydroxyl radical resulting from oxygen-dependent oxidation of l-ascorbic acid via copper redox-catalyzed reactions - RSC Advances (RSC Publishing) https://pubs.rsc.org/en/content/articlelanding/2016/ra/c6ra02843h#!divAbstract