Nanostructured Dioxomolybdenum(VI) Catalyst for the Liquid-Phase Epoxidation of Olefins

作者：Castro Alichandra; Alonso Joao C; Valente Anabela A^*; Neves Patricia; Brandao Paula; Felix Vitor; Ferreira Paula

来源：European Journal of Inorganic Chemistry, 2010, (9): 1405-1412.

DOI：10.1002/ejic.200901093

• Molybdenum
• Mesoporous materials
• Heterogeneous catalysis
• Epoxidation

A new organosilica hybrid mesoporous material (HM) containing phosphane oxide surface groups was prepared via the "dual" organosilane templated co-condensation of 4-bis-(triethoxysilyl)benzene and (diphenylphosphanyl)propyltriethoxysilane, followed by post-synthesis oxidation of the phosphane surface groups. The HM material was used to immobilise the [Mo(O)(2)Cl(2)] complex. The resultant material (HM-Mo) is an active and selective catalyst in the liquid-phase epoxidation of olefins [cis-cyclooctene, (R)-(+)-limonene, trans-2-octene, 1-octene] with tBuOOH at 55 degrees C and gives comparable epoxide yields to those observed for the free complex [MoCl(2)(O)(2){OP(CH(2)CH(3))(Ph)(2)}(2)] (1), under similar reaction conditions: the crystal structure of complex 1 remains the same after reaction with tBuOOH. The oxidant is essentially consumed in the HM-Mo or 1 catalysed epoxidation of the olefin. In the case of limonene (possesses endo- and exocyclic C=C bonds), the molar ratio of 1,2-epoxy-p-menth-8-ene/1,2-8,9-diepoxy-p-menthane at ca. 90% conversion (reached after 24 h reaction) is ca. 5 and 10 for 1 and HM-Mo, respectively, indicating a favourable regioselectivity towards the epoxidation of the endocyclic C1-C2 double bond, especially in the case of the heterogeneous catalyst.

• 出版日期2010-3