Epoxidation of α-pinene catalyzed by methyltrioxorhenium(VII): Influence of additives, oxidants and solvents

Michel, Typhène; Betz, Daniel; Cokoja, Mirza; Sieber, Volker; Kühn, Fritz E.

doi:10.1016/j.molcata.2011.03.017

Cited by 33 publications

(10 citation statements)

References 55 publications

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“…[13][14][15] Cyclopentadienyl (Cp) Mo complexes sometimes display activities similar to or even higher than that of the well-examined methyltrioxorhenium (MTO)-H 2 O 2 system. [16][17][18][19][20] During the past decade, monomeric CpMo tricarbonyl complexes have been established as suitable precursors for catalytically active molybdenum dioxo or oxo-peroxo complexes, which are formed in situ with organic hydroperoxides after oxidative decarbonylation. [21][22][23] Homogeneous epoxidation activities of CpMo complexes as catalysts have been compared in a recent review 10 and other reviews have discussed heterogenization and catalytic applications of the aforementioned category of molybdenum catalysts.…”

Section: Introductionmentioning

confidence: 99%

Cyclopentadienyl molybdenum alkyl ester complexes as catalyst precursors for olefin epoxidation

Grover

Pöthig

Kühn

2014

Catal. Sci. Technol.

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New molybdenum complexes of the type [CpMo(CO) 3 X] containing ligands of the formula X = CHR 2 CO(OR 1 )where R 1 = ethyl (1), menthyl (4), and bornyl (5) and R 2 = H; R 1 = ethyl and R 2 = methyl (2) and phenyl (3) have been synthesized and characterized by NMR and IR spectroscopy and X-ray crystallography.These compounds have been applied as catalyst precursors for achiral and chiral epoxidation of unfunctionalized olefins with tert-butyl hydroperoxide (TBHP) as the oxidant at 22°C (in CH 2 Cl 2 ) and 55°C (in CHCl 3 ). The substrates cis-cyclooctene, 1-octene, cis-and trans-stilbene, and trans-β-methylstyrene were selectively and quantitatively converted into their epoxides using a catalyst :substrate : oxidant ratio of 1 : 100 : 200 within 4 h at room temperature in CH 2 Cl 2 and within 15 min at 55°C in CHCl 3 . Complexes 1-5 are precursors of active epoxidation catalysts and turnover frequencies (TOFs) of ca. 1200 h −1 are obtained with cis-cyclooctene as the substrate. No enantioselectivity is observed with trans-β-methylstyrene as the substrate despite the application of enantiomerically pure precatalysts. In situ monitoring of catalytic epoxidation of cis-cyclooctene with complex 5 by 1 H and 13 C NMR spectroscopy suggests that the chiral alkyl ester side chain is retained during oxidation with TBHP. During epoxidation, the primary catalytic species is the dioxo complex [CpMoO 2 X]. After near complete conversion of cis-cyclooctene to its epoxide, further oxidation of the dioxo complex to oxo-peroxo complex [CpMo(η 2 -O 2 )(O)X] takes place. The oxo-peroxo complex is also an active epoxidation catalyst.

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Section: Introductionmentioning

confidence: 99%

Cyclopentadienyl molybdenum alkyl ester complexes as catalyst precursors for olefin epoxidation

Grover

Pöthig

Kühn

2014

Catal. Sci. Technol.

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“…The best and straightforwardly applicable system was reported only last year by Ku ¨hn and co-workers (Table 2, entry 4). 54 Camphene Camphene oxide can be successfully obtained through epoxidation of camphene with a variety of transition metal complexes, in contrast to a-pinene. Nevertheless, MTO (3) features once again among the best catalysts.…”

Section: A-pinenementioning

confidence: 99%

Epoxidation of olefins with homogeneous catalysts – quo vadis?

Hauser

Cokoja

Kühn

2013

Catal. Sci. Technol.

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“…The Lewis acidity of the rhenium centre causes hydrolysis and cleavage of the epoxide ring leading to the formation of 1,2-diols [5,[8][9][10][11][12]. The presence of water in the reaction mixture accelerates the splitting of epoxide, which reduces the possibility of using an aqueous solution of hydrogen peroxide as an oxidant.…”

Section: Introductionmentioning

confidence: 99%

“…The formation of secondary products can be partially avoided by the usage of an appropriate combination of additives. There have been published results showing that pyridine and related compounds are able to enhance the rate of the MTO-catalysed epoxidation reactions while also tempering the Lewis acidity of the Re-centre and thereby protecting the epoxide [5,[8][9][10][11][12]. Recent studies of Yamazaki [5] showed that the use of a derivative of pyrazole, 3-methylpyrazole, with MTO in the epoxidation of indene creates a system with even higher catalytic activity and also results in a longer lifetime of the catalyst [5,11,12].…”

Section: Introductionmentioning

confidence: 99%

Indene epoxidation over immobilized methyltrioxorhenium on MCM-41 silica, fumed silica and aluminosilicate materials

et al. 2014

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The presented report focuses on the testing of heterogenized methyltrioxorhenium (MTO) in indene epoxidation. A range of mesoporous materials with different SiO 2 /Al 2 O 3 ratios, namely aluminosilicates type Siral and MCM-41 silica and fumed silica, were used as supports for immobilization of MTO. The tested support materials and prepared catalytic systems exhibited high surface area, well-defined regular structure and narrow pore size distribution of mesopores and therefore represent good quality catalysts for various reactions. The immobilized MTO on various supports was tested for the preparation of 1,2-epoxyindane using two forms of hydrogen peroxide as oxidation agents, namely aqueous solution of hydrogen peroxide and its anhydrous form, urea-hydrogen peroxide. The prepared catalysts were successfully used for the preparation of 1,2-epoxyindane with achieved 100 % selectivities to the desired product at high conversions of indene.

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Epoxidation of α-pinene catalyzed by methyltrioxorhenium(VII): Influence of additives, oxidants and solvents

Cited by 33 publications

References 55 publications

Cyclopentadienyl molybdenum alkyl ester complexes as catalyst precursors for olefin epoxidation

Cyclopentadienyl molybdenum alkyl ester complexes as catalyst precursors for olefin epoxidation

Epoxidation of olefins with homogeneous catalysts – quo vadis?

Indene epoxidation over immobilized methyltrioxorhenium on MCM-41 silica, fumed silica and aluminosilicate materials

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