Peroxotantalate‐Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide

Ma, Wenbao; Chen, Chen; Kong, Kang; Dong, Qifeng; Li, Kun; Yuan, Mingming; Li, Difan; Hou, Zhenshan

doi:10.1002/chem.201605661

Cited by 20 publications

(9 citation statements)

References 101 publications

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“…The linearity of the Arrhenius plots was investigated to obtain the activation energy, E a = 52.1 kJ·mol –1 . The activation energy calculated under current conditions is slightly lower than those of niobium-based and tantalum-based homogeneous epoxidation catalysts reported previously, , and comparable with those of tungsten-based catalysts for epoxidation reported in the literature (49–86 kJ·mol –1 ). , However, the value is higher than those of some Nb-polyoxometalate and Nb-silicate catalysts. , …”

Section: Resultssupporting

confidence: 84%

Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation

Zhou

Tang

et al. 2021

Langmuir

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We present here that easily available organic salts can stabilize/modify niobium (Nb) oxo-clusters. The as-synthesized Nb oxo-clusters have been characterized by various methods. These Nb oxo-clusters were catalytically active for the epoxidation of allylic alcohols and olefins with H2O2 as an oxidant. Notably, Nb-OC@TBAF-0.5 appeared as highly dispersed nanosized particles and showed the highest catalytic activity, which can be attributed to the following reasons on the basis of characterization. First, the strong coordination of fluorine ions with Nb sites and the steric protection with bulky organic cations led to high stabilization and dispersion of the oxo-clusters in the course of the reaction. Second, a hydrogen-bond interaction between the coordinated fluorine atom and the −OH group of allylic alcohol favored the epoxidation reaction. Third, the electron density of Nb sites decreased due to the strong electron-withdrawing ability of F– adjacent to Nb sites, thus promoting the electrophilic oxygen transfer to the CC bond.

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Section: Resultssupporting

confidence: 84%

Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation

Zhou

Tang

et al. 2021

Langmuir

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“…With regard to the results of other groups and our previous research, the epoxidation of olefins showed reasonable first-order plots for the concentration of substrate and zero-order dependence on the concentration of hydrogen peroxide at low concentrations. ,, To eliminate the diffusion limitations, the effect of stirring speeds and the amount of catalysts on the reaction rate was investigated, and the results are shown in Figure S10. Next, the reaction kinetics of each catalyst were investigated and the activation energy was attained.…”

Section: Resultsmentioning

confidence: 60%

“…Recently, we have developed a series of highly catalytically active peroxoniobate (peroxotantalate)-based IL catalysts for the selective epoxidation of allylic alcohols. , These IL catalysts showed a higher turnover frequency (TOF) in comparison to the previously reported Nb-/Ta-based heterogeneous catalysts and dinuclear tungstate-based catalysts. However, these peroxoniobate (peroxotantalate)-based IL catalysts exhibited only a very limited catalytic activity for the epoxidation of olefins, which is an even more important reaction than the epoxidation of allylic alcohols in the chemical industry.…”

Section: Introductionmentioning

confidence: 99%

Identifying Catalytically Active Mononuclear Peroxoniobate Anion of Ionic Liquids in the Epoxidation of Olefins

Yuan

Wang

et al. 2018

ACS Catal.

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The organic carboxylic acid coordinated monomeric peroxoniobate-based ionic liquids (ILs) [TBA][NbO(OH)2(R)] (TBA = tetrabutylammonium; R = lactic acid (LA), glycolic acid (GLY), malic acid (MA)) were prepared and fully characterized by elemental analysis, NMR, IR, Raman, TGA, 93Nb NMR, and HRMS. These IL catalysts exhibited not only high catalytic activity for the epoxidation of olefins under very mild reaction conditions, as the turnover frequency of [TBA][NbO(OH)2(LA)] reached up to 110 h–1, but also satisfactory recyclability in the epoxidation by using only 1 equiv of hydrogen peroxide as an oxidant. Meanwhile, this work revealed that the ILs underwent structural transformation from [NbO(OH)2(R)]− to [Nb(O–O)2(R)]− (R = LA, GLY, MA) in the presence of H2O2 by a subsequent activity evaluation, characterization, and first-principles calculations. Moreover, the organic carboxylic acid coordinated monomeric peroxoniobate-based ILs were investigated using density functional theory (DFT) calculations, which identified that [Nb(O–O)2LA]− was more advantageous than [Nb(O–O)2(OOH)2]− for the epoxidation of olefins. Due to the coordination between the α-hydroxy acids and the monomeric peroxoniobate anions, the functionalized ILs can efficiently catalyze the epoxidation of a wide range of olefins and allylic alcohols under very mild conditions. Additionally, the effect of solvents on the reaction is illustrated. It was found that methanol can lower the epoxidation barriers by forming a hydrogen bond with a peroxo ligand attached to the niobium center.

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“…A new series of quaternary phosphonium salts consisting of quaternary phosphonium cation P 444n cation, n=4, 8, 14 and monomeric peroxotantalate anion Ta(O) 3 (η‐O 2 ) has been developed as efficient catalysts for epoxidation of allylic alcohols under mild conditions, by using only one equivalent of hydrogen peroxide as an oxidant . Epoxidation reaction was carried out on the model substrate 3‐methyl‐2‐buten‐1‐ol in the presence of phosphonium‐based catalysts, H 2 O 2 , in different solvents: acetonitrile, methanol, and ethyl acetate.…”

Section: The Use Of Phosphonium Ionic Liquids As Catalystsmentioning

confidence: 99%

Phosphonium‐Based Ionic Liquids Used as Reagents or Catalysts

2019

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The role and enlarged importance of ionic liquids (ILs) in chemical reactions were already exhaustively demonstrated. The aim of this review is to promote the family of the phosphonium‐based ILs used as reagents and catalysts, which gained increased interest in the last decade. The common and beneficial properties of ILs refer to their negligible vapour pressure, non‐toxicity, reusability, and high thermal stability. Therefore, phosphonium‐based ionic liquids are used successfully as catalysts and reagents in many chemical reactions, and additionally allow the syntheses in mild reaction conditions. Phosphonium ILs have proved their catalytic efficiency in many reactions such as epoxidation of olefins and allylic alcohol, in synthesis of alpha‐aminophosphonates, beta‐ketophosphonates, nitrogen‐containing bisphosphonates, the Michaelis‐Arbuzov reactions, esterification, coupling reaction, aromatic chlorination, dehydrogenation. The major advantage of phosphonium‐based ILs used as catalysts is that they can be reused with only little loss of catalytic activity. Phosphonium ILs revealed their potential as Wittig reagents, halogenation reagents for bromination and bromo‐chlorination reactions with alkenes and alkynes, as monomer and as initiator in frontal polymerization of acrylates. From the literature data, it can be concluded that due to their structure and physical‐chemical properties phosphonium ILs can be tailored function of their purpose.

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Peroxotantalate‐Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide

Cited by 20 publications

References 101 publications

Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation

Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation

Identifying Catalytically Active Mononuclear Peroxoniobate Anion of Ionic Liquids in the Epoxidation of Olefins

Phosphonium‐Based Ionic Liquids Used as Reagents or Catalysts

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