Mechanisms of hydrogen-, oxygen-, and electron-transfer reactions of cumylperoxyl radical

被引:90
作者
Fukuzumi, S
Shimoosako, K
Suenobu, T
Watanabe, Y
机构
[1] Osaka Univ, Dept Mat & Life Sci, Grad Sch Engn, Suita, Osaka 5650871, Japan
[2] Nagoya Univ, Grad Sch Sci, Dept Chem, Chikusa Ku, Nagoya, Aichi 4648602, Japan
关键词
D O I
10.1021/ja035156o
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Rates of hydrogen-transfer reactions from a series of para-substituted N,N-dimethylanilines to cumylperoxyl radical and oxygen-transfer reactions from cumylperoxyl radical to a series of sulfides and phosphines have been determined in propionitrile (EtCN) and pentane at low temperatures by use of ESR. The observed rate constants exhibit first-order and second-order dependence with respect to concentrations of N, N-dimethylanilines. This indicates that the hydrogen- and oxygen-transfer reactions proceed via 1:1 charge-transfer (CT) complexes formed between the substrates and cumylperoxyl radical. The primary kinetic isotope effects are determined by comparing the rates of N,N-dimethylanilines and the corresponding N,N-bis(trideuteriomethyl)anilines. The isotope effect profiles are quite different from those reported for the P-450 model oxidation of the same series of substrates. Rates of electron-transfer reactions from ferrocene derivatives to cumylperoxyl radical have also been determined by use of ESR. The catalytic effects of Sc(OTf)(3) (OTf = triflate) on the electron-transfer reactions are compared with those of Sc(OTf)(3) on the hydrogen- and oxygen-transfer reactions. Such comparison provides strong evidence that the hydrogen- and oxygen- transfer reactions of cumylperoxyl radical proceed via a one-step hydrogen atom and oxygen atom transfer rather than via an electron transfer from substrates to cumylperoxyl radical.
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页码:9074 / 9082
页数:9
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