Structure and reactivity of vanadium(V) complexes formed in the reaction between vanadyl acetylacetonate and alkyl hydroperoxides. To the mechanism of selective epoxidation of olefins

Talsi, Evgenii P.; Chinakov, V. D.; Babenko, V. P.; Zamaraev, K. I.

doi:10.1007/bf02068415

Cited by 9 publications

(6 citation statements)

References 9 publications

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“…In our earlier theoretical modeling work on the homogeneous VO(acac) 2 catalyst, we found that first vacant coordination sites should be created to activate the catalyst 30 . This is in accordance with earlier literature data 34 . For the MIL-47, free coordination positions should also be created by removing a ligand or by folding one terephthalic acid ligand away from the vanadium center or by removing bridging oxygen between the neighboring vanadium centers from the O-V-O axis.…”

Section: Selection Of the Cluster Modelsupporting

confidence: 94%

The coordinatively saturated vanadium MIL-47 as a low leaching heterogeneous catalyst in the oxidation of cyclohexene

Leus

Vandichel

Liu

et al. 2012

Journal of Catalysis

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A Metal Organic Framework, containing coordinatively saturated V +IV sites linked together by terephthalic linkers (V-MIL-47) is evaluated as a catalyst in the epoxidation of cyclohexene. Different solvents and conditions are tested and compared. If the oxidant TBHP is dissolved in water, a significant leaching of V-species into the solution is observed and also radical pathways are 2 prominently operative leading to the formation of an adduct between the peroxide and cyclohexene. If however the oxidant is dissolved in decane, leaching is negligible and the structural integrity of the V-MIL-47 is maintained during successive runs. The selectivity towards the epoxide is very high in these circumstances. Extensive computational modelling is performed to show that several reaction cycles are possible. EPR and NMR measurements confirm that at least two parallel catalytic cycles are co-existing: one with V +IV sites and one with pre-oxidized V +V sites, and this in complete agreement with the theoretical predictions.

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Section: Selection Of the Cluster Modelsupporting

confidence: 94%

The coordinatively saturated vanadium MIL-47 as a low leaching heterogeneous catalyst in the oxidation of cyclohexene

Leus

Vandichel

Liu

et al. 2012

Journal of Catalysis

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“…Concomitantly, AC6 complexes are also the most common AC species in the Sharpless epoxidation process. 13,14,16,38,39 Moreover, the results do not support the hypothesis that the regioselectivity of the Sharpless epoxidation toward allylic alcohols is thermodynamically driven, as previously proposed. 40,41 TSs and Activation Barriers.…”

Section: ■ Results and Discussioncontrasting

confidence: 85%

“…A detailed description of the catalytic cycle for the VO(acac) 2 /TBHP system has eluded the efforts of several authors because of the lability of the acac ligands , and their tendency to irreversibly decompose into acetic acid (AcOH) and carbon dioxide (CO 2 ) . Recently, Vandichel et al published a comprehensive theoretical study of the catalytic cycle for the epoxidation of cyclohexene using the VO(acac) 2 /TBHP system.…”

Section: Introductionmentioning

confidence: 99%

Driving Forces in the Sharpless Epoxidation Reaction: A Coupled AIMD/QTAIM Study

et al. 2017

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In order to better understand the epoxide-formation step of the Sharpless epoxidation process, a set of 263 oxygen-transfer reactions reflecting the complexity of the Sharpless epoxidation process were studied using density functional theory (DFT) and Bader's quantum theory of atoms in molecules (QTAIM). The diversity within these reactions reflects the different ligands in the coordination sphere of vanadium and also different substrates (alkene and an allylic alcohol both free and in the form of an alcoxo ligand). The transition states for 76 of these reactions were also characterized using DFT and QTAIM, allowing for an estimation of the impact of the different ligands and substrates on the activation barriers. A smaller subset of the latter was further subjected to an ab initio molecular dynamics (AIMD) simulation coupled to QTAIM analysis. The results show that the type of active catalyst plays an important role in the thermodinamic outcome of these reactions, with vanadium(V) tert-butylhydroperoxide adducts being responsible for the most exoenergetic reactions. On the other hand, the different ligands tested play only a limited role in modulating the thermodynamics and kinetics of these reactions. Moreover, no evidence was found to support a thermodynamic or kinetic preference for the epoxidation of an allylic alcohol over that of an unfunctionalized alkene. However, the results suggest that the reaction path is strongly influenced by the orientation of the substrate upon approximation to the active catalyst, confirming the well-known regioselectivity of the Sharpless epoxidation process.

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“…The allyl alcohol (30 %) and minor amounts (<2 %) of enones were formed as byproducts [47,48] . VO(acac) 2 is also known to catalyze the epoxidation of alkenes with sacrificial inexpensive peroxides such as H 2 O 2 or tert ‐butyl hydroperoxide [49–51] . Accordingly, we adopted an epoxidation protocol by addition of 30 mol% t BuOOH to the cardanyl hydroperoxide mixture which enhanced the yield of the desired epoxy alcohols to 88 % and prevented the formation of allyl alcohol byproducts.…”

Section: Resultsmentioning

confidence: 99%

Light‐Driven Waste‐To‐Value Upcycling: Bio‐Based Polyols and Polyurethanes from the Photo‐Oxygenation of Cardanols

Stuhr

Bayer²,

Stark

et al. 2021

ChemSusChem

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The upcycling of waste biomass into valuable materials by resource‐efficient chemical transformations is a prime objective for sustainable chemistry. This approach is demonstrated in a straightforward light‐driven synthesis of polyols and polyurethane foams from the multi‐ton waste products of cashew nut processing. The photo‐oxygenation of cardanol from nutshell oil results in the formation of synthetically versatile hydroperoxides. The choice of the workup method (i. e., reduction, hydrogenation, epoxidation) enables access to a diverse range of alcohols with tunable alkene and OH functions. Condensation with isocyanates to give rigid polyurethane foams provides a resource‐efficient waste‐to‐value chain that benefits from the availability of cardanol and installation of OH groups from aerial O2.

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Structure and reactivity of vanadium(V) complexes formed in the reaction between vanadyl acetylacetonate and alkyl hydroperoxides. To the mechanism of selective epoxidation of olefins

Cited by 9 publications

References 9 publications

The coordinatively saturated vanadium MIL-47 as a low leaching heterogeneous catalyst in the oxidation of cyclohexene

The coordinatively saturated vanadium MIL-47 as a low leaching heterogeneous catalyst in the oxidation of cyclohexene

Driving Forces in the Sharpless Epoxidation Reaction: A Coupled AIMD/QTAIM Study

Light‐Driven Waste‐To‐Value Upcycling: Bio‐Based Polyols and Polyurethanes from the Photo‐Oxygenation of Cardanols

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