Epoxidation, heterogeneous

Among the large bulk of work regarding titanium(IV) silsesquioxanes, specific studies have been focused on synthesizing close molecular models of the active sites of titanium heterogeneous epoxidation catalysts in siUcaUte and in mesostruc-tured MCM-41 silica (Figure 14.3 gives some selected examples) [54, 61-66]. 

Interestingly, the enantiomeric excess in trans-(l/ ,27 )- 1-phenylpropylene oxide was 76%. This enantioselectivity is the highest one ever observed during heterogeneous epoxidation starting from trans P-methylstyrene. 

NEW POLYDENTATE Mo(VI) - GRAFTED POLY(AMIDO AMINE) RESINS AS HETEROGENEOUS EPOXIDATION CATALYSTS... 

The search for new environmentally-friendly epoxidation methods using 02 as a sole oxidant has attracted much interest. Although there has been some success with 02 and homogeneous catalyst systems in the liquid phase without the use of reducing reagents, there have been few reports concerning heterogeneous epoxidation of olefins [45, 46]. 

Ueno, S., Yamaguchi, K., Yoshida, K., Ebitani, K. and Kaneda, K. Hydrotalcite catalysis heterogeneous epoxidation of olefins using hydrogen peroxide in the presence of nitriles, Chem. Commun., 1998, 295-296. 

Various methods for anchoring Gp titanium derivatives onto organic or inorganic supports have been developed. Heterogeneous epoxidation catalysts have been prepared by the co-polycondensation of Cp2TiCl2 and (CpTiCl2)20 with tetraethoxysilane by a modified sol-gel procedure, and the use in epoxidations of non-activated olefins have been described.1936... 

Epoxidation, where PO and a,a-dimethylbenzyl alcohol (cumyl alcohol, CA) are obtained from CHP and propene, in the presence of a proprietary heterogeneous epoxidation catalyst. 

CATALYSTS AND RATES IN COMMODITY AND HETEROGENEOUS EPOXIDATION PROCESSES... 

A. Klust, R. J. Madix, Selectivity limitations in the heterogeneous epoxidation of olefins Branching reactions of the oxametallacycle intermediate in the partial oxidation of styrene, /. Am. Chem. Soc. 128 (2006) 1034. 

Mechanisms in Homogeneous and Heterogeneous Epoxidation Catalysis DOI 10.1016/B978-0-444-53188-9.00002-X... 

K. Yamaguchi, C. Yoshida, S. Uchida, N. Mizuno, Peroxotungstate immobilized on ionic liquid-modified silica as a heterogeneous epoxidation catalyst with hydrogen peroxide, J. Am. Chem. Soc. 127 (2005) 530. 

R. M. Lambert, R. L. Cropley, A. Husain, M. S. Tikhov, Halogen-induced selectivity in heterogeneous epoxidation is an electronic effect—fluorine, chlorine, bromine and iodine in the Ag-catalysed selective oxidation of ethene, Chem. Comm. (2003) 1184. 

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