Effects of metal ions distinguishing between one-step hydrogen- and electron-transfer mechanisms for the radical-scavenging reaction of (+)-catechin

被引：70

作者：

Nakanishi, I ^{[1
]}

Miyazaki, K

Shimada, T

Ohkubo, K

Urano, S

Ikota, N

Ozawa, T

Fukuzumi, S

Fukuhara, K

机构：

[1] Natl Inst Radiol Sci, Redox Regulat Res Grp, Res Ctr Radiat Safety, Inage Ku, Chiba 2638555, Japan

[2] Natl Inst Hlth Sci, Div Organ Chem, Setagaya Ku, Tokyo 1588501, Japan

[3] Shibaura Inst Technol, Dept Appl Chem, Minato Ku, Tokyo 1088548, Japan

[4] Osaka Univ, Dept Mat & Life Sci, Grad Sch Engn, CREST,JST, Suita, Osaka 5650871, Japan

来源：

JOURNAL OF PHYSICAL CHEMISTRY A | 2002年 / 106卷 / 46期

关键词：

D O I：

10.1021/jp026190c

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

A kinetic study of a hydrogen-transfer reaction from (+)-catechin (1) to galvinoxyl radical (G.) has been performed using UV-vis spectroscopy in the presence of Mg(ClO4)(2) in deaerated acetonitrile (MeCN).,The rate constants of hydrogen transfer from 1 to G. detennined from the decay of the absorbance at 428 rim due to G. increase significantly with an increase in the concentration of Mg2+. The kinetics of hydrogen transfer from 1 to cumylperoxyl radical has also been examined in propionitrile (EtCN) at low temperature with use of ESR. The decay rate of cumylperoxyl radical in the presence of 1 was also accelerated by the presence of scandium triflate [Sc(OTf)(3) (OTf = OSO2CF3)]. These results indicate that the hydrogen-transfer reaction of (+)-catechin proceeds via electron transfer from 1 to oxyl radicals followed by proton transfer rather than via a one-step hydrogen atom transfer. The coordination of metal ions to the one-electron reduced anions may stabilize the product, resulting in the acceleration of electron transfer.

引用

页码：11123 / 11126

页数：4