Methyltrioxorhenium revisited: improving the synthesis for a versatile catalyst

Tosh, Evangeline; Mitterpleininger, J.; Rost, Alexandra M. J.; Veljanovski, Draganco; Herrmann, Wolfgang A.; Kühn, Fritz E.

doi:10.1039/b709072b

Cited by 27 publications

(19 citation statements)

References 18 publications

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“…MTO was synthesised according to literature procedures. [34] Ligand Synthesis: Ligands 1-3 were synthesised by treating a solution of 4-picoline (2.48 mmol) in THF at -60°C with an equimolar amount of lithium diisopropylamine in THF. [35] The alcoholate was formed upon addition of the corresponding aldehyde, which was subsequently eliminated by refluxing in concentrated acetic acid for 18 h to form the C-C double bond.…”

Section: Discussionmentioning

confidence: 99%

Chromophoric Lewis Base Adducts of Methyltrioxorhenium: Synthesis, Catalysis and Photochemistry

et al. 2010

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A series of chromophoric Lewis base adducts of methyltrioxorhenium (MTO) was examined. The ligands were pyridine derivatives with different size of the aromatic system and variable substituents, thus providing a variation of electronic and steric parameters. The complexes were fully characterised (UV/Vis, IR and NMR spectroscopy, single-crystal X-ray diffraction and elemental analysis) and their stability constants in dichloromethane were determined by means of UV/Vis spectroscopy. Moreover, this report presents a study of the influence of these N-donor ligands coordinated to MTO on the catalytic activity of epoxidation of 1-octene.

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Section: Discussionmentioning

confidence: 99%

Chromophoric Lewis Base Adducts of Methyltrioxorhenium: Synthesis, Catalysis and Photochemistry

et al. 2010

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“…For example, the EXAFS indicates the presence of two different Re-containing species: (1) intact MTO, interacting via the oxo ligands with Lewis acid sites present on the γ-Al 84 which evolves to [W(OCH 2 t Bu) 2 (CH t Bu)Cl 2 ] and generates "(AlOCl) n " as an incompletely characterized sideproduct. 85 To confirm the exchange of oxygen for chloride at ReO, we grafted 17 O-enriched MTO onto Cl−Al 2 O 3 and characterized the resulting material by 17 O MAS NMR. The chemical shift of ReO is observed at ca.…”

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

“…86 The spectrum of MTO/Cl−Al 2 O 3 in Figure S13c is devoid of such signals. However, supported metal-oxo species can be difficult to observe by solid-state 17 O MAS NMR, due to their large chemical shift anisotropies, and the presence of a distribution of sites which further broadens signals and prevents their efficient observation. 87 Nevertheless, a signal is visible at 13 ppm, with a shoulder at 50 ppm.…”

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

Ligand Exchange-Mediated Activation and Stabilization of a Re-Based Olefin Metathesis Catalyst by Chlorinated Alumina

Gallo¹,

Fong²,

Szeto

et al. 2016

J. Am. Chem. Soc.

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Extensive chlorination of γ-AlO results in the formation of highly Lewis acidic surface domains depleted in surface hydroxyl groups. Adsorption of methyltrioxorhenium (MTO) onto these chlorinated domains serves to activate it as a low temperature, heterogeneous olefin metathesis catalyst and confers both high activity and high stability. Characterization of the catalyst reveals that the immobilized MTO undergoes partial ligand exchange with the surface, whereby some Re sites acquire a chloride ligand from the modified alumina while donating an oxo ligand to the support. More specifically, Re L-edge EXAFS and DFT calculations support facile ligand exchange between MTO and Cl-AlO to generate [CHReOCl] fragments that interact with a bridging oxygen of the support via a Lewis acid-base interaction. According to IR and solid-state NMR, the methyl group remains intact, and does not evolve spontaneously to a stable methylene tautomer. Nevertheless, the chloride-promoted metathesis catalyst is far more active and productive than MTO/γ-AlO, easily achieving a TON of 100 000 for propene metathesis in a flow reactor at 10 °C (compared to TON < 5000 for the nonchlorinated catalyst). Increased activity is a consequence of both a larger fraction of active sites and a higher intrinsic activity for the new sites. Increased stability is tentatively attributed to a stronger interaction between MTO and chlorinated surface regions, as well as extensive depletion of the Brønsted acidic surface hydroxyl population. The reformulated catalyst represents a major advance for Re-based metathesis catalysts, whose widespread use has thus far been severely hampered by their instability.

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“…However, several well-defined transition metal epoxidation catalysts already operate at room temperature and atmospheric pressure with impressively high turnover frequencies and good stability against ''green solvents" such as water. Most prominent among them is methyltrioxorhenium (MTO) being available since quite recently from non-toxic, low price starting materials [8,9] and several organometallic and inorganic molybdenum and tungsten catalysts, employing comparatively cheap metals and being able to provide chiral ligand environments for chiral epoxidation [10,11] catalysis. The major drawback of most of these systems is their inability to utilize oxygen as an oxidizing agent, and, in part, the difficulty in immobilizing them on proper carrier materials or matrices and to obtain high epoxide selectivities [12].…”

Section: Introductionmentioning

confidence: 99%

((2-Hydroxynapthalen-1-yl)methylene)aniline derived Schiff base adducts of MTO: Synthesis and catalytic application

Capapé

Zhou

Zang

et al. 2008

Journal of Organometallic Chemistry

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Methyltrioxorhenium revisited: improving the synthesis for a versatile catalyst

Cited by 27 publications

References 18 publications

Chromophoric Lewis Base Adducts of Methyltrioxorhenium: Synthesis, Catalysis and Photochemistry

Chromophoric Lewis Base Adducts of Methyltrioxorhenium: Synthesis, Catalysis and Photochemistry

Ligand Exchange-Mediated Activation and Stabilization of a Re-Based Olefin Metathesis Catalyst by Chlorinated Alumina

((2-Hydroxynapthalen-1-yl)methylene)aniline derived Schiff base adducts of MTO: Synthesis and catalytic application

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