Titanium-catalyzed heterogeneous oxidations of silanes, chiral allylic alcohols, 3-alkylcyclohexanes, and thianthrene 5-oxide:: A comparison of the reactivities and selectivities for the large-pore zeolite Ti-β, the mesoporous Ti-MCM-41, and the layered alumosilicate Ti-ITQ-2

被引:53
作者
Adam, W [1 ]
Corma, A
García, H
Weichold, O
机构
[1] Univ Wurzburg, Inst Organ Chem, D-97074 Wurzburg, Germany
[2] Univ Politecn Valencia, CSIC, Inst Tecnol Quim, E-46071 Valencia, Spain
关键词
zeolites; heterogeneous oxidation; silanes; allylic alcohols; thianthrene; 5-oxide;
D O I
10.1006/jcat.2000.3043
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 comparative study of silane oxidation, olefin epoxidation, and thianthrene 5-oxide sulfoxidation with the oxidants Ti-beta /H2O2, Ti-MCM-41/t-BuOOH, and Ti-ITQ-2/t-BuOOH provides the catalytic reactivity order Ti-beta > Ti-MCM-41 > Ti-ITQ-2. The steric constraints of the narrow channels make the Ti-beta zeolite the most selective. For the more open structures of the Ti-MCM-41 and Ti-ITQ-2 hosts, such steric constraints are less pronounced and, therefore, a lower selectivity is exhibited by these heterogeneous catalysts. Both activate t-BuOOH for oxygen transfer through a transition structure analogous to the homogeneous Ti(Oi-Pr)(4)/t-BuOOH oxidant. (C) 2000 Academic Press.
引用
收藏
页码:339 / 344
页数:6
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