抗坏血酸在水溶液缓冲液中与 2-苯基-4,4,5,5-四甲基咪唑啉-1-氧自由基 3-氧化物（PTIO˙）反应的大动力学同位素效应。
A large kinetic isotope effect in the reaction of ascorbic acid with 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO˙) in aqueous buffer solutions.
机构信息
Quantitative RedOx Sensing Group, Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), Quantum Medical Science Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan.
出版信息
Chem Commun (Camb). 2020 Sep 29;56(77):11505-11507. doi: 10.1039/d0cc05214k.
A large kinetic isotope effect (KIE, kH/kD) of 12.8 was observed for the hydrogen-transfer reaction from ascorbic acid to 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO˙) in a phosphate buffer solution (0.05 M, pH/pD 7.0) at 298 K. The isotopic difference in the activation energies (6.8 kJ mol-1) determined from the temperature dependence of the KIE suggests that quantum mechanical tunneling may partly play a role in the reaction, although the isotopic ratio of the Arrhenius prefactor (AH/AD = 0.86) is within the semiclassical limits.
在 298 K 下，在磷酸盐缓冲溶液（0.05 M，pH/pD 7.0）中，观察到抗坏血酸向 2-苯基-4,4,5,5-四甲基咪唑啉-1-氧-3-氧化物（PTIO˙）的氢转移反应的大动力学同位素效应（KIE，kH/kD）为 12.8。从 KIE 的温度依赖性确定的活化能的同位素差异（6.8 kJ mol-1）表明，量子力学隧道效应可能部分参与了反应，尽管 Arrhenius 前因子的同位素比（AH/AD = 0.86）在半经典极限内。
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