A kineticstudy involving 4-hydroxycinnamic acid derivatives (HCAs) was performed in order to clarify the mechanism for free radical-scavenging and vitamin E-regenerating. The second-order rate con...
为了阐明自由基清除和维生素 E 再生的机制,进行了涉及 4-羟基肉桂酸衍生物 (HCA) 的动力学研究。二阶速率控制...
Formation and Decay Dynamics of Vitamin E Radical in the Antioxidant Reaction of Vitamin E
understand the dynamics of antioxidant actions of vitaminE (α-, β-, γ-, and δ-tocopherols, TocH) in biological systems, kinetic study of the formation and decay reactions of vitaminEradicals (α-, β-, γ-, and δ-tocopheroxyls, Toc•) has been performed in organic solvents, using stopped-flow spectrophotometry. By mixing α-, β-, γ-, and δ-TocH with aryloxyl radical (ArO•) in ethanol, the peaks of the UV-vis
为了了解维生素 E(α-、β-、γ-和 δ-生育酚,TocH)在生物系统中的抗氧化作用动力学,对维生素 E 自由基(α-、β -、γ- 和 δ-生育酚 (Toc•) 已在有机溶剂中使用停流分光光度法进行了分析。通过将 α-、β-、γ- 和 δ-TocH 与芳氧基 (ArO•) 在乙醇中混合,α-、β-、γ- 和 δ-Toc• 自由基引起的 UV-vis 吸收峰迅速出现在ca。430-340 nm,出现最大值,然后逐渐衰减。α-Toc• 的形成和衰变(即双分子歧化)反应的二级速率常数(kf 和 2k d )是通过将观测曲线与通过相关微分方程数值计算获得的模拟曲线进行比较来确定的。对上述反应。根据结果,确定了α-Toc•自由基的光谱的最大吸收波长(λ max i) 和摩尔消光系数(ei ) (i = 1-4)。已经观察到显着的溶剂效应对于 α-Toc• 自由基的反应速率(kf 和 2k d
Vitamin E Chemistry. Studies into Initial Oxidation Intermediates of α-Tocopherol: Disproving the Involvement of 5a-<i>C</i>-Centered “Chromanol Methide” Radicals
days of vitaminE research, one-electron oxidation of vitaminE does not involve 5a-C-centered radicals. A combined approach of analytical techniques, in particular electron paramagnetic resonance spectroscopy (EPR), organic synthesis of special derivatives, isotopic labeling, kinetic studies, and computational chemistry was used to re-evaluate the one-electron and two-electron oxidation chemistry of α-tocopherol
Absolute Rate Constants for Some Intermolecular Reactions of α-Aminoalkylperoxyl Radicals. Comparison with Alkylperoxyls
作者:Jacques Lalevée、Xavier Allonas、Jean-Pierre Fouassier、K. U. Ingold
DOI:10.1021/jo800925g
日期:2008.9.1
alpha-aminoalkylperoxyl radicals have been generated by 355 nm laser flash photolysis (LFP) of oxygen-saturated di-tert-butyl peroxide containing mono-, di-, and trialkylamines and a dialkylarylamine. All these peroxyls possess absorptions in the near-UV (strongest for the trialkylamine-derived peroxyls) which permits direct monitoring of the kinetics of their reactions with many substrates. The measured rate constants
The rate constants for the reaction of primary alkyl radicals with substituted phenolic compounds have been measured in benzene or toluene at room temperature by using the radical clock technique. With three representative phenols, containing in the ortho positions substituents of different size, the kinetics of the hydrogen transfer to alkyl radicals was studied at different temperatures to obtain the