Halide substituted Schiff-bases: Different activities in methyltrioxorhenium(VII) catalyzed epoxidation via different substitution patterns

Altmann, Philipp J.; Cokoja, Mirza; Kühn, Fritz E.

doi:10.1016/j.jorganchem.2011.12.010

Cited by 20 publications

(10 citation statements)

References 46 publications

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“…Because the high activation barrier of 173 kJ mol À1 is at odds with the good observed yields (at least 50 %), the ratelimiting step has been recalculated with the experimentally used substrate (cyclooctene), which is known to be more easily epoxidized than the model olefin (ethene). [35] The resulting activation barrier of 143 kJ mol À1 demonstrates better agreement between the chosen computational model and the experimental data, as well as the far better reactivity of cyclooctene in comparison to ethene. Assuming a firstorder reaction and a pre-exponential factor of 10 13 s À1 , we estimate a barrier of about 110 kJ mol À1 based on the observed 50 % yield after 4 h.…”

Section: Mechanistic Considerations Of the Activation Of H 2 O 2 : Thmentioning

confidence: 64%

Activation of Hydrogen Peroxide by Ionic Liquids: Mechanistic Studies and Application in the Epoxidation of Olefins

Markovits

Eger

Yue

et al. 2013

Chemistry A European J

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Imidazolium-based ionic liquids that contain perrhenate anions are very efficient reaction media for the epoxidation of olefins with H2O2 as an oxidant, thus affording cyclooctene in almost quantitative yields. The mechanism of this reaction does not follow the usual pathway through peroxo complexes, as is the case with long-known molecular transition-metal catalysts. By using in situ Raman, FTIR, and NMR spectroscopy and DFT calculations, we have shown that the formation of hydrogen bonds between the oxidant and perrhenate activates the oxidant, thereby leading to the transfer of an oxygen atom onto the olefin demonstrating the special features of an ionic liquid as a reaction environment. The influence of the imidazolium cation and the oxidant (aqueous H2O2, urea hydrogen peroxide, and tert-butyl hydrogen peroxide) on the efficiency of the epoxidation of cis-cyclooctene were examined. Other olefinic substrates were also used in this study and they exhibited good yields of the corresponding epoxides. This report shows the potential of using simple complexes or salts for the activation of hydrogen peroxide, owing to the interactions between the solvent medium and the active complex.

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Section: Mechanistic Considerations Of the Activation Of H 2 O 2 : Thmentioning

confidence: 64%

Activation of Hydrogen Peroxide by Ionic Liquids: Mechanistic Studies and Application in the Epoxidation of Olefins

Markovits

Eger

Yue

et al. 2013

Chemistry A European J

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“…In our preliminary experiments using methanol or acetonitrile as ESI solvents, it was observed that the metallic triflates and triflimides, either in positive or negative mode, produced noisy mass spectra of rather poor quality. Our search for a suitable solvent led us to consider nitromethane, which is widely used as medium for synthesis and spectrometric characterization of organometallic compounds and in studies of catalytic effects, owing to its solubility properties and its weak coordinating ability. Moreover, nitromethane was frequently used as reaction medium in synthesis trials .…”

Section: Electrospray Ms Investigationmentioning

confidence: 99%

Metal triflates and triflimides as Lewis “superacids”: preparation, synthetic application and affinity tests by mass spectrometry

Gal

Iacobucci

Monfardini

et al. 2012

J of Physical Organic Chem

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Metal salts of triflic acid, CF 3 SO 2 OH and of triflimidic acid, [CF 3 SO 2 ] 2 NH, often called "Lewis superacids", are powerful catalysts for several classes of reactions. Typical applications developed at the Institut de Chimie de Nice during the last decade, mostly in the domain of inter-and intramolecular carbon-carbon, carbon-oxygen and carbon-sulfur bond formation, are illustrated. During the last three years, the characterization of metal triflates and triflimides by electrospray mass spectrometry was also accomplished in our Institute. Displacement of one anion of the salt by strong neutral ligands was developed as a mean for generating characteristic positive ions. In an effort toward the quantitative description of the ligand/metal bonding and the catalytic role of the Lewis acid, a ligand competition method was devised. An exploratory study attests that subtle structural effects on the donor/acceptor interaction can be evidenced using this simple mass spectrometric method. Al(OTf) 3 (5 mol%) CH 2 Cl-CH 2 Cl, reflux 30 min 83% S COOH O S O Scheme 9. Hydrocarboxylation of olefins catalyzed by Al(III) triflate SH In(OTf) 3 (5 mol%) CH 3 NO 2 , reflux 1.5 h S 91% Scheme 10. Hydrothiolation of olefins catalyzed by In(III) triflate

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“…[1][2][3][4] In the last decade, several soluble Schiff base complexes of Cr, [4,5] Mo, [4,6,7] Re, [8] Ni, [9] Co, [10,11] Mn, [12,13] V, [14][15][16][17] Cu, [18] Ru [19] and Ti [20] have been employed as active homogeneous catalysts in the epoxidation of alkenes. However, most of these catalysts are expensive and contaminate the environment.…”

Section: Introductionmentioning

confidence: 99%

Schiff base‐functionalized boehmite nanoparticle‐supported molybdenum and vanadium complexes: efficient catalysts for the epoxidation of alkenes

Mirzaee

Bahramian

Amoli

2015

Applied Organom Chemis

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Boehmite nanoparticles, with high surface area and high degree of surface hydroxyl groups, were prepared via hydrothermal-assisted sol-gel processing of aluminium 2-butoxide. The produced powder was covalently functionalized with 3-(trimethoxysilyl)propylamine, and then, in order to support vanadium oxosulfate and molybdenum hexacarbonyl complexes, all the terminal amine groups were changed to Schiff bases by refluxing with salicylaldehyde. These catalysts were applied in the epoxidation of cis-cyclooctene and other olefins with tert-BuOOH in CCl 4 . The catalytic procedures for both catalysts were optimized for various parameters such as solvent and oxidant. Recycling experiments revealed that these heterogeneous nano-catalysts could be repeatedly applied for the epoxidation of alkenes.

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Halide substituted Schiff-bases: Different activities in methyltrioxorhenium(VII) catalyzed epoxidation via different substitution patterns

Cited by 20 publications

References 46 publications

Activation of Hydrogen Peroxide by Ionic Liquids: Mechanistic Studies and Application in the Epoxidation of Olefins

Activation of Hydrogen Peroxide by Ionic Liquids: Mechanistic Studies and Application in the Epoxidation of Olefins

Metal triflates and triflimides as Lewis “superacids”: preparation, synthetic application and affinity tests by mass spectrometry

Schiff base‐functionalized boehmite nanoparticle‐supported molybdenum and vanadium complexes: efficient catalysts for the epoxidation of alkenes

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