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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Nitrogen Dioxide Reaction with Nitroxide Radical Derived from Hydroxamic Acids: The Intermediacy of Acyl Nitroso and Nitroxyl (HNO)
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Nitrogen Dioxide Reaction with Nitroxide Radical Derived from Hydroxamic Acids: The Intermediacy of Acyl Nitroso and Nitroxyl (HNO)

机译：衍生自羟肟酸的氮二氧化氮反应：酰基亚硝基和硝基氧基（HNO）的中间体

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摘要

Hydroxamic acids (RC(O)NHOH) form a class of compounds that display interesting chemical and biological properties The chemistry of RC(O)NHOH) is associated with one- and two-electron oxidations forming the respective nitroxide radical (RC(O)NHO~(?)) and acyl nitroso (RC(O)N═O), respectively, which are relatively unstable species. In the present study, the kinetics and mechanism of the ~(?)NO_(2) reaction with nitroxide radicals derived from acetohydroxamic acid, suberohydroxamic acid, benzohydroxamic acid, and suberoylanilide hydroxamic acid have been studied in alkaline solutions. Ionizing radiation was used to generate about equal yields of these radicals, demonstrating that the oxidation of the transient nitroxide radical by ~(?)NO_(2) produces HNO and nitrite at about equal yields. The rate constant of ~(?)NO_(2) reaction with the nitroxide radical derived from acetohydroxamic acid has been determined to be (2.5 ± 0.5) × 10~(9) M~(–1) s~(–1). This reaction forms a transient intermediate absorbing at 314 nm, which decays via a first-order reaction whose rate increases upon increasing the pH or the hydroxamic acid concentration. Transient intermediates absorbing around 314 nm are also formed during the oxidation of hydroxamic acids by H_(2)O_(2) catalyzed by horseradish peroxidase. It is shown that HNO is formed during the decomposition of these intermediates, and therefore, they are assigned to acyl nitroso compounds. This study provides for the first time a direct spectrophotometric detection of acyl nitroso compounds in aqueous solutions allowing the study of their chemistry and reaction kinetics.
机译：羟肟酸（RC（O）NHOH）形成一类显示有趣的化学和生物学性质的化合物，RC（O）NHOH的化学与形成相应的硝基氧化物基团的单电子氧化（RC（O）相关联NHO〜（α））和酰基亚硝基（RC（O）NO═O），它们是相对不稳定的物种。在本研究中，已经研究了碱性溶液中衍生自乙酰致羟肟酸，脱氟羟肟酸，苯羟肟酸和Suberoylanilide羟肟酸的氮氧化物自由基的动力学和机制。使用电离辐射产生约相等的这些基团的产率，证明了通过〜（α）NO_（2）产生的瞬时氮氧化物的氧化在约相等产率下产生HNO和亚硝酸盐。 〜（α）NO_（2）与衍生自乙酰致羟肟酸的氮氧化物自由基的速率常数已被确定为（2.5±0.5）×10〜（9）m〜（-1）〜（-1）。该反应在314nm处形成瞬态中间吸收，其经由一阶反应衰减，其速率在增加pH或羟肟酸浓度时增加。在通过辣根过氧化物酶催化的H_（2）O_（2）催化的羟肟酸的氧化过程中也形成吸收约314nm的瞬态中间体。结果表明，在这些中间体的分解过程中形成HNO，因此，它们被分配给酰基亚硝基化合物。该研究提供了第一次直接分光光度测量检测水溶液中的酰基亚硝基化合物，允许研究其化学和反应动力学。

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