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首页> 美国卫生研究院文献>Biochemical Journal >Studies on the photolytic breakdown of hydroperoxides and peroxidized fatty acids by using electron spin resonance spectroscopy. Spin trapping of alkoxyl and peroxyl radicals in organic solvents.
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Studies on the photolytic breakdown of hydroperoxides and peroxidized fatty acids by using electron spin resonance spectroscopy. Spin trapping of alkoxyl and peroxyl radicals in organic solvents.

机译：用电子自旋共振光谱研究氢过氧化物和过氧化脂肪酸的光解。在有机溶剂中自旋捕获烷氧基和过氧自由基。

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Spin trapping using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) has been used to detect and distinguish between the carbon-centred, alkoxyl, and peroxyl radicals produced during the photolytic decomposition of hydroperoxides. Photolysis of tert-butyl and cumene hydroperoxides, and peroxidized fatty acids, in toluene, with low levels of u.v. light, is shown to lead to the initial production of alkoxyl radicals by homolysis of the oxygen-oxygen bond. Subsequent reaction of these radicals with excess hydroperoxide leads, by hydrogen abstraction, to the production of peroxyl radicals that can be detected as their corresponding adducts with the spin trap. Subsequent breakdown of these adducts produces alkoxyl radicals and a further species that is believed to be the oxidized spin-trap radical 5,5-dimethyl-1-pyrrolidone-2-oxyl. No evidence was obtained at low hydroperoxide concentrations, with either the cumene or lipid alkoxyl radicals, for the occurrence of beta-scission reactions; the production of low levels of carbon-centred radicals is believed to be due to the alternative reactions of hydrogen abstraction, ring closure, and/or 1,2 hydrogen shifts. Analogous experiments with 3,3,5,5-tetramethyl-1-pyrroline N-oxide (TMPO) led only to the trapping of alkoxyl radicals with no evidence for peroxyl radical adducts, this is presumably due to a decreased rate of radical addition because of increased steric hindrance.
机译：使用5,5-二甲基-1-吡咯啉N-氧化物（DMPO）的自旋捕集已被用于检测和区分在氢过氧化物的光解过程中产生的碳中心，烷氧基和过氧自由基。叔丁基和异丙苯氢过氧化物和过氧化脂肪酸在甲苯中的光解，其紫外线含量低可见，通过氧-氧键的均相分解，导致最初产生烷氧基自由基。这些自由基与过量氢过氧化物的随后反应通过夺氢导致过氧自由基的产生，过氧自由基可作为自旋阱的相应加合物而被检测到。这些加合物的随后分解产生烷氧基基团和另一种被认为是氧化的自旋陷阱基团的5,5-二甲基-1-吡咯烷酮-2-氧基。在低氢过氧化物浓度下，无论是异丙苯还是脂质烷氧基，都没有证据表明发生β-分裂反应。人们认为，产生低水平的碳中心自由基是由于吸氢，闭环和/或1,2个氢位移的交替反应所致。用3,3,5,5-四甲基-1-吡咯啉N-氧化物（TMPO）进行的类似实验仅导致了烷氧基的捕获，而没有过氧自由基加合物的证据，这大概是由于自由基加成率降低所致，因为位阻增加。

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