Dioxomolybdenum(VI) Epoxidation Catalyst Supported on Mesoporous Silica Containing Phosphane Oxide Groups

Abstract

A new mesoporous hybrid material (denoted LP-TEPPPOMo) has been prepared by tethering [MoO 2 Cl 2 ] onto mesoporous silica previously functionalised with phosphane oxide spacer ligands. The LP-TEPPPO-Mo material was tested in the liquid-phase epoxidation of olefins [cis-cyclooctene, (R)-(+)-limonene, trans-2-octene and 1-octene] with tBuOOH, at 55°C, and without a co-solvent, giving at least 90 % selectivity to the corresponding epoxide at 36-77 % conversion: in the case of limonene, regioselectivity favours the epoxidation of the endocyclic double bond, giving mainly 1,2-epoxy-p-

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

“…High catalyst stability has also been reported by the group of Thiel for (i) complexes of the type [MoO(O 2 ) 2 ] supported on hybrid supports synthesised by sol-gel copolymerisation of a chelate ligand with TEOS, [26,27] and (ii) the complex [MoO-(O 2 ) 2 L] {L = (3-triethoxysilylpropyl)-[3-(2-pyridyl)pyrazol-1-yl]acetamide} supported on a hydrophobic phenylenebridged mesoporous organosilica. [48] The catalytic performance of HM-Mo is superior to that recently reported for a catalyst prepared by tethering [Mo(O) 2 Cl 2 ] onto a preformed mesoporous silica functionalised with phosphane oxide spacer ligands: [28] Mo and P leaching and a concomitant decrease in catalytic activity were observed for the used catalyst. The higher catalyst stability of HMo in compari-son to the catalyst prepared through the tethering synthetic approach may be related to its hydrophobic, uniform, single-site features.…”

“…[25] Alternatively, efficient solid epoxidation catalysts have been prepared by supporting molybdenum(VI) complexes on MesoSiHyb materials via ligand exchange reactions. [26,27] Recently, some of us reported on the catalytic performance of a mesostructured hybrid materials prepared by introducing [Mo(O) 2 Cl 2 ] in a preformed mesoporous silica functionalised with phosphane oxide spacer ligands: [28] in general, epoxide selectivity was excellent, albeit the occurrence of Mo and P leaching during catalysis and a concomitant decrease in catalytic activity of the used catalyst was observed, which could be related to the diversity of surface metal species. In this work, a new hybrid mesoporous material (HM) has been prepared by co-condensation of the organosilanes 1,4-bis(triethoxysilyl)benzene (BTEB -carries the organic component of the matrix) and (diphenylphosphanyl)propyltriethoxysilane (TEPPP -for pending phosphane groups) in the presence of Pluronics P123 as a template, followed by template removal (through chemical treatment) and post-synthesis oxidation of the phosphane surface groups into phosphane oxide.…”

Borane-Protecting Strategy for Hydrosilylation of Phosphorus-Containing Olefins

“…13 Diphenyl[3-(triethoxysilyl)propyl]phosphine Oxide (5a). 34 In a test tube with a PTFE screw cap, DABCO (56.0 mg, 0.5 mmol) was equipped. Toluene (2.5 mL) and 2a (100.0 mg, 0.25 mmol) were successively added to the test tube.…”

Recent Advances in Facile Liquid Phase Epoxidation of Light Olefins over Heterogeneous Molybdenum Catalysts

“…The good performance of the catalyst rendered this protocol very useful in industry. Castro et al . prepared a new mesoporous hybrid material (LP‐TEPPPO‐Mo) by tethering MoO 2 Cl 2 onto functionalized mesoporous silica.…”

“…The good performance of the catalyst rendered this protocol very useful in industry. Castro et al [114] prepared a new mesoporous hybrid material (LP-TEPPPO-Mo) by tethering MoO 2 Cl 2 onto functionalized mesoporous silica. The LP-TEPPPO-Mo catalyst ( Table 5, #48-50) showed higher reaction rate and epoxide selectivity than those of LP-TEPPPO (Table S5, #51).…”