Rahhal S, Richter H W
Department of Chemistry, University of Akron, Ohio 44325.
Free Radic Res Commun. 1989;6(6):369-77. doi: 10.3109/10715768909087920.
Reactions of the hydroxyl radical with ferrous and ferric diethylenetriamine-N,N,N',N",N"-pentaacetate (DTPA) complexes in neutral aqueous solution were studied using a 60Co-gamma radiolysis source for radical production. Hydroxyl radicals oxidize the ferrous chelate of DTPA to the ferric chelate, as determined by changes in the optical absorbance. In the presence of equimolar concentrations of ferric and ferrous chelates, HO. is "trapped" by Fe(III)DTPA2- and yields of Fe(III)DTPA2- are substantially reduced. Both tert-butyl alcohol and methanol react efficiently with hydroxyl radicals. tert-Butyl alcohol produces unreactive radicals, and is thus an effective scavenger. However, the reducing hydroxymethyl radical produced upon reaction of HO. with methanol effectively reduces Fe(III)DTPA2- present in the system, so that solutions initially containing the more absorbing Fe(III)DTPA2- are bleached. These results with alcoholic hydroxyl radical scavengers illustrate possible complications from scavengers such as methanol which produce reactive products which may themselves stimulate further reaction.
使用钴-60γ辐射分解源产生自由基，研究了中性水溶液中羟基自由基与二乙烯三胺-N,N,N',N",N"-五乙酸铁（Ⅱ）和铁（Ⅲ）配合物（DTPA）的反应。通过吸光度的变化确定，羟基自由基将DTPA的亚铁螯合物氧化为铁（Ⅲ）螯合物。在等摩尔浓度的铁（Ⅲ）和铁（Ⅱ）螯合物存在下，HO·被Fe(III)DTPA2-“捕获”，Fe(III)DTPA2-的产率大幅降低。叔丁醇和甲醇都能有效地与羟基自由基反应。叔丁醇产生无反应性的自由基，因此是一种有效的清除剂。然而，HO·与甲醇反应产生的还原性羟甲基自由基有效地还原了体系中存在的Fe(III)DTPA2-，使得最初含有吸收性更强的Fe(III)DTPA2-的溶液被漂白。这些使用醇类羟基自由基清除剂的结果说明了像甲醇这样的清除剂可能带来的并发症，甲醇会产生可能自身引发进一步反应的活性产物。
