Pyridines as bifunctional co-catalysts in the CrO3-catalyzed oxygenation of olefins by t-butyl hydroperoxide

被引：42

作者：

Rothenberg, G ^{[1
]}

Wiener, H ^{[1
]}

Sasson, Y ^{[1
]}

机构：

[1] Hebrew Univ Jerusalem, Casali Inst Appl Chem, IL-91904 Jerusalem, Israel

来源：

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL | 1998年 / 136卷 / 03期

关键词：

allylic oxidation; olefin epoxidation; pyridine; t-butyl hydroperoxide; chromium trioxide; semi-empirical calculations; chelated complexes;

D O I：

10.1016/S1381-1169(98)00070-3

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：

t-Butyl hydroperoxide (TBHP) oxidizes olefins to epoxides and allylic oxidation products in the presence of a Cr(VI) catalyst. A concurrent decomposition of the oxidant occurs. Pyridine-derived additives alter the behavior of this catalytic system: monodentate pyridines and trans-chelated bidentate bipyridines retard the decomposition of TBHP, and arrest the epoxidation reaction, shifting the product selectivity towards allylic oxidation. Adversely, cis-chelated bipyridines accelerate the decomposition of TBHP. Depending on ligand nature and concentration, the initial decomposition rate can be slowed down to 1/8th, or accelerated up to two orders of magnitude, (relative to CrO3 catalysis). The allylic oxidation and the TBHP decomposition are free-radical reactions, but the epoxidation is evidently not. A reaction mechanism is proposed, where the diverse role of the pyridine ligands is attributed to specific complex formations. (C) 1998 Elsevier Science B.V. All rights reserved.

引用

页码：253 / 262

页数：10

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