Transition-metal-catalyzed epoxidations

Joergensen, Karl Anker

doi:10.1021/cr00093a001

Cited by 1,046 publications

(415 citation statements)

References 147 publications

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“…36,37 Catalytic oxidation of organic sulfides remains a topical interest due to the versatile utility of both sulfoxides and sulfones in organic synthesis. [38][39][40] While a mass of oxygen donors are available, utilization of H2O2 as "green" oxygen donor has become increasingly prominent.…”

Section: Resultsmentioning

confidence: 99%

Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides

Hong

Win

Zhang

et al. 2016

Chemistry A European J

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Structural and chemical stability of the immobilized polyoxometalates (POMs)-containing catalysts is one crucial factor for their industrial application. In this work, we discuss the preparation of a novel P2W15@Al2O3 catalyst using a facile condensation reaction between the tri-lacunary POM of Na12[α-P2W15O56]·24H2O (P2W15) and the hydroxyl groups on the surface of the spherical γ-Al2O3 under acidic conditions. The heterogeneous catalyst was characterized by the 31 P NMR, FT-IR, XRD, XPS, TG, Raman, HR-TEM and BET. The P2W15@Al2O3 catalyst showed excellent stability, highly efficient reactivity and selectivity for the oxygenation of thioethers to sulfoxides which are a very useful intermediate in organic synthesis and industrial preparation of drugs. The catalyst could be recycled and reused at least ten times without any observable loss of its catalytic efficiency, mainly due to the covalently grafted {P2W15} cluster and high dispersion onto the γ-Al2O3 surface.Polyoxometalates (POMs) are a class of discrete anionic metal-oxides of V, Mo, W and Nb etc.

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Section: Resultsmentioning

confidence: 99%

Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides

Hong

Win

Zhang

et al. 2016

Chemistry A European J

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“…Complex 3 3+ has also been tested with regards to its ability to oxidize alkenes. The catalytic reactions have been carried out using a catalyst:substrate:oxidant:water ratio of 1:2000:4000:4000 after a 120 min mixing period of catalyst 2 2+ in the absence of substrate (see Experimental Section for further details), during which the excess of water ensures the generation of the oxidant PhIO species from PhI(OAc) 2 49 and of the bis-aqua derivative 3 3+ from its chloro counterpart 2 2+ . This mixing period before substrate addition is crucial in order to improve the rate of the catalytic reaction.…”

Section: +mentioning

confidence: 99%

“…1,2 Epoxides constitute a family of essential chemicals, particularly for the synthesis of various polymers (polyglycols, polyamides, polyurethanes, etc. ), 3,4 and fine chemicals such as pharmaceuticals, food additives or flavor and fragrance compounds.…”

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confidence: 99%

Powerful Bis-facially Pyrazolate-Bridged Dinuclear Ruthenium Epoxidation Catalyst

et al. 2015

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ABSTRACT:A new bis-facial dinuclear ruthenium complex, {[Ru II (bpy)] 2 (μ-bimp)(μ-Cl)} 2+ , 2 2+ , containing a hexadentate pyrazolate-bridging ligand (Hbimp) and bpy as auxiliary ligands has been synthesized and fully characterized in solution by spectrometric, spectroscopic and electrochemical techniques. The new compound has been tested with regard to its capacity to oxidize water and alkenes. The in situ generated bis-aqua complex, {[Ru II (bpy)(H 2 O)] 2 (μ-bimp)} 3+ , 3 3+ , results in low efficiencies and selectivities when oxidizing water, but is an excellent catalyst for the epoxidation of a wide range of alkenes. High turnover numbers (TN), up to 1900, and turnover frequencies (TOF), up to 73 min -1 , are achieved using PhIO as oxidant. Moreover, 3 3+ presents an outstanding stereospecificity for both cis and trans olefins towards the formation of their corresponding epoxides due to specific interactions transmitted by its ligand scaffold. A mechanistic analysis of the epoxidation process has been performed based on DFT calculations in order to better understand the putative cooperative effects within this dinuclear catalyst.The epoxidation of olefins, a process of great industrial and economical importance, has historically constituted a great challenge for the organic synthetic chemists. 1,2 Epoxides constitute a family of essential chemicals, particularly for the synthesis of various polymers (polyglycols, polyamides, polyurethanes, etc.), 3,4 and fine chemicals such as pharmaceuticals, food additives or flavor and fragrance compounds. 5 For instance, propylene oxide monopolizes the epoxide chemical business with a yearly 8 million Ton production and an expected annual increase of 5%. 6 Ru complexes are excellent catalysts for redox transformations such as alcohol oxidation, 7,8,9,10,11,12,13,14 sulfoxidation, 15,16,17,18 water oxidation 19,20,21,22,23,24,25,26,27,28 and epoxidation. 14,29,30,31,32,33,34,35,36,37 In all these cases, a Ru IV =O or Ru V =O group has been shown to be the active catalytic unit. Most of the literature related to redox catalysis using Ru complexes is based on mononuclear complexes, since they are generally easily accessible from a synthetic point of view. In sharp contrast, two powerful diruthenium epoxidation catalysts in terms of epoxide selectivity and substrate conversion have been recently reported by our research group. 38,39 In addition, these new catalysts display distinctive reactivity with regards to cis and trans alkenes. Both features are proposed to be caused by a hydrogen bonding interaction between the second Ru IV =O site and the substrate employed, together with steric effects.Our group has an extensive experience on the synthesis, characterization and evaluation of the oxidative catalytic performance of dinuclear Ru complexes, most of them inspired by the well-known {[Ru II (trpy)] 2 (μ-bpp)(μ-Cl)} 2+ water oxidation catalyst. 40 Modifications around this paradigmatic compound, like the replacement of the trpy auxiliary ligands by facially coordinating ...

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“…Although a number of epoxidation processes that use various catalysts and oxidants have been developed, a chlorine-based noncatalytic process (the chlorohydrin process) and catalytic processes based on expensive oxidants are still used extensively [10].…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature and Reaction Time on the Synthesis of Butadiene Monoepoxide Using Iron Complex as an Efficient Catalyst

Zong¹,

Kharismadewi²,

Sup³

et al. 2012

Clean Technology

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at -10 ℃ with low catalyst loadings by using commercially available peracetic acid as an oxidant. The main aspect of our study is to investigate the effect of temperature (from -10 to -40 ℃) and time on the epoxidation reaction. The epoxidation reaction was fast and almost completed within 5 min at temperatures above -20 ℃, whereas it became slow at temperatures below -20 ℃. The yield of butadiene monoepoxide (BMO)increased with increasing the reaction time. Generally, when the more butadiene was used, the higher yield was obtained. The highest yield of BMO was 90%.

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Transition-metal-catalyzed epoxidations

Cited by 1,046 publications

References 147 publications

Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides

Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides

Powerful Bis-facially Pyrazolate-Bridged Dinuclear Ruthenium Epoxidation Catalyst

Effect of Temperature and Reaction Time on the Synthesis of Butadiene Monoepoxide Using Iron Complex as an Efficient Catalyst

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