H2O2-based epoxidation of bridged cyclic alkenes with [P{Ti(O2)}2W10O38]7- in monophasic systems:: active site and kinetics

被引:35
作者
Gao, FX
Yamase, T
Suzuki, H
机构
[1] Tokyo Inst Technol, Chem Resources Lab, Midori Ku, Yokohama, Kanagawa 2268503, Japan
[2] Nissan Chem Ind Co Ltd, Cent Res Inst, Funabashi, Chiba 2748507, Japan
基金
日本学术振兴会;
关键词
Keggin-type hydroperoxotitanium complex bridged cyclic alkene epoxidation; H2O2; PNMR spectroscopy; Ti-active species for epoxidation;
D O I
10.1016/S1381-1169(01)00445-9
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
The H2O2-based epoxidation of bridged cyclic alkenes in a monophasic system containing low concentrations (<2 mM) of [(BU4N)-N-n](4)[(Pr2NH3)-N-i](2)H[P[Ti(O-2)}(2)W10O38] (.) H2O (1) (with two eta(2)-peroxotitanium sites in the anion) has been studied in search of the catalytically active species involved. P-31 NMR spectra of 1, measured under a variety of conditions, revealed that the active species was not hydroperoxotitanium complex [P{Ti(OOH)}(2)W10O38](7-) or [P{Ti(OOH)}Ti(O-2)W10O38](7-). The reaction pathways for the alkene epoxidation are discussed to understand the kinetics (especially the initial [H2O2] dependence). It was concluded that the net catalytic reaction for the epoxidation occurred through the two-electron oxidation at the hydroperoxotitanium site in the catalyst. (C) 2002 Elsevier Science B.V. All rights reserved.
引用
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页码:97 / 108
页数:12
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