Efficient Epoxidation Of Olefins Research Articles

Construction of a highly stable natural silicate-supported molybdenum catalyst for efficient epoxidation of olefins

Epoxides are important bulk chemicals, playing irreplaceable role in the chemical industry, but facing serious pollution and low productivity in the production process. Therefore, the development of green and efficient epoxidation of olefins by stable catalysts with low prices is of great significance. In this study, a Mo-MATP catalyst was prepared by modifying Mo(CO)₆ on attapulgite through Si-O bonding. Mo-MATP exhibits excellent performance (99% yield of cyclooctane oxide, CYCO) and stability (80% selectivity of CYCO after 17 cycles), highly tert-butyl hydroperoxide (TBHP) utilization, and extensive substrate scalability. Furthermore, the in-situ Fourier Transform Infrared Spectroscopy (FT-IR), Electron Spin-resonance Spectroscopy (ESR) and High Resolution Mass Spectrometry (HRMS) spectra suggest that TBHP would be activated by Mo-MATP to generate peroxyl radicals, which then oxidize alkenes to their corresponding epoxides. In this study, the stable loading of Mo would largely solve the problem of Mo loss during the catalytic process, thus providing a stable and dispersed Mo active center, enabling the catalyst to possess high catalytic performance and recycling stability.

Optimisation of greener and more efficient 1,7-octadiene epoxidation catalysed by a polymer-supported Mo(vi) complex via response surface methodology

In this study, a greener and more efficient alkene epoxidation process has been developed using a heterogeneous polybenzimidazole supported Mo(vi) catalyst and tert-butyl hydroperoxide (TBHP) as an oxidising reagent.

Efficient olefin epoxidation with high turnover rates over ordered mesoporous silica nanoparticles with uniform manganese sites

Olefin epoxidation has been studied over a series of mesoporous manganese silicate nanoparticles and tBuOOH. Partial substitution of Si by Mn in silica framework leads to highly dispersed, distorted Mn(III) sites, confirmed by various physicochemical analyses. High conversion and stable styrene oxide, stilbene oxide and epoxy cyclohexane yield have been achieved with MS75 with 1:1.5 ratio of olefin: oxidant. However, at faster reaction rates lower styrene oxide yield is observed at lower Mn-containing catalyst (MS100). High TON, TOF over manganese sites shows accessible monomeric Mn sites. Attributed to high reactant density at redox-active Mn silicate sites due to facile diffusion across shallow pore depth channels of nanoparticulate om-MSx and surface hydrophobic characteristics. The catalysts were found to be stable under recycling and filtration experiments. The excellent stability against leaching of active manganese species indicates stable sites and good textural properties in om-MSx, essential for extended activity.

Tandem catalytic efficient olefin epoxidation with integrated production of nicotinamide derivatives

Tandem catalytic efficient olefin epoxidation with integrated production of nicotinamide derivatives

Efficient Epoxidation of Olefins by Silica Supported Dioxidomolybdenum(VI) Coordination Compounds

Efficient Epoxidation of Olefins by Silica Supported Dioxidomolybdenum(VI) Coordination Compounds

The efficient heterogeneous catalyst containing copper (II) bis-benzothiazole complex supported on functionalized magnetic nanoparticles used for epoxidation of alkenes with tert-BuOOH

In this article, efficient and novel catalyst including copper (II) 3,5–bis(2–benzothiazolyl)pyridine supported on silica-coated magnetite nanoparticles, [Cu(II)Br2-BTP@MNPs], was investigated for epoxidation of alkenes. The prepared catalyst was characterized by elemental analysis, XRD, ICP, FE-SEM, VSM, TGA and FT-IR spectroscopic techniques. This new heterogeneous catalyst can be developed for efficient epoxidation of alkenes with tert-BuOOH in acetonitrile as solvent under mild conditions. Also, the reusability of this catalyst in the epoxidation reactions was investigated.

Recent Advances in Greener and Energy Efficient Alkene Epoxidation Processes

The chemical industry is considered to be one of the largest consumers of energy in the manufacturing sector. As the cost of energy is rising rapidly, coupled with the increasingly stringent standards for the release of harmful chemicals and gases into the environment, more attention is now focused on developing energy efficient chemical processes that could significantly reduce both operational costs and greenhouse gas emissions. Alkene epoxidation is an important chemical process as the resultant epoxides are highly reactive compounds that are used as platform chemicals for the production of commercially important products for flavours, fragrances, paints and pharmaceuticals. A number of epoxidation methods have been developed over the past decade with the ultimate aim of minimising waste generation and energy consumption. In this review paper, some of the recent advances in epoxides synthesis using energy efficient processes are discussed. The epoxidation methods may provide sustainability in terms of environmental impact and energy consumption.

Seed-Assisted Synthesis of Hierarchically Structured Nano-Sized Ti-β Zeolites for the Efficient Epoxidation Reaction of Alkenes.

The development of nano-sized titanosilicate zeolites with hierarchical structures is crucial in promoting the efficient epoxidation of alkenes. In the present work, nano-sized hierarchical Ti-β (*BEA) zeolites with high crystal yield are prepared by a one-pot nanoseed-assisted approach. The influence of seed size on the resultant Ti-β zeolites is investigated by complementary characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption/desorption, UV-vis diffuse reflectance spectroscopy (DRS), and UV Raman spectroscopy. The possible process for the formation of hierarchical Ti-β nanocrystals with the assistance of nanoseeds in the synthesis gel is proposed. Consequentially, the nano-sized hierarchical material prepared by the nanoseed-assisted method shows excellent mass transportation and accessibility to active sites by reducing particle size and constructing hierarchical porosity, hence showing a remarkably enhanced catalytic activity and selectivity in the epoxidation reaction of alkenes. This work will shed light on the efficient preparation of nano-sized titanosilicate zeolites.

A thermo-responsive MOF-based H2O2-in-oil “pickering emulsion in situ catalytic system” for highly efficient olefin epoxidation

A thermo-responsive MOF has been designed as a highly efficient Pickering emulsifier to stabilize the H2O2-in-oil emulsion. The resultant emulsion displayed good catalytic performance in epoxidation of olefins and easy catalyst-product separation.

Amphiphilic peroxo polyoxometalate as reaction control phase transfer catalyst for efficient epoxidation of olefins

A peroxo polyoxometalate-based catalyst was synthesized, characterized, and employed as a catalyst in the epoxidation of olefins with hydrogen peroxide (H2O2). During the reaction, the insoluble catalyst became soluble and an emulsion formed to promote the epoxidation process. Then the emulsion broke and the catalyst precipitated for reuse easily.

Selective and Efficient Olefin Epoxidation by Robust Magnetic Mo Nanocatalysts

Iron oxide magnetic nanoparticles were synthesized with different sizes (11 and 30 nm). Subsequently they were shelled with a silica layer allowing grafting of an organic phosphine ligand that coordinated to the [MoI2(CO)3] organometallic core. The silica layer was prepared by the Stöber method using either mechanical (both 11 and 30 nm nanoparticles) or ultrasound (30 nm only) stirring. The latter nanoparticles once coated with silica were obtained with less aggregation, which was beneficial for the final material holding the organometallic moiety. The Mo loadings were found to be 0.20, 0.18, and 0.34 mmolMo·g−1 for MNP30-Si-phos-Mo,MNP11-Si-phos-Mo, and MNP30-Sius-phos-Mo, respectively, with the ligand-to-metal ratio reaching 4.6, 4.8, and 3.2, by the same order, confirming coordination of the Mo moieties to two phos ligands. Structural characterization obtained from powder X-ray diffraction (XRD), scanning electron microscopy (SEM)/ transmission electron microscopy (TEM) analysis, and Fourier-transform infrared (FTIR) spectroscopy data confirmed the successful synthesis of all nanomaterials. Olefin epoxidation of several substrates catalyzed by these organometallic nano-hybrid materials using tert-butyl hydroperoxide (tbhp) as oxidant, achieved very good results. Extensive testing of the catalysts showed that they are highly active, selective, recyclable, and efficient concerning oxidant consumption.

Highly selective and efficient olefin epoxidation with pure inorganic-ligand supported iron catalysts.

Over the past two decades, there have been major developments in the transition iron-catalyzed selective oxidation of alkenes to epoxides; a common structure found in drug, isolated natural products, and fine chemicals. Many of these approaches have enabled highly efficient and selective epoxidation of alkenes via the design of specialized ligands, which facilitates to control the activity and selectivity of the reactions catalyzed by iron atom. Herein, we report the development of the olefin epoxidation with inorganic-ligand supported iron-catalysts using 30% H2O2 as an oxidant, and the mechanism is similar to iron-porphyrin type. With the catalyst 1, (NH4)3[FeMo6O18(OH)6], various aromatic and aliphatic alkenes were successfully transformed into the corresponding epoxides with excellent yields as well as chemo- and stereo-selectivity. This catalytic system possesses the advantages of being able to avoid the use of expensive, toxic, air/moisture sensitive and commercially unavailable organic ligands. The generality of this methodology is simple to operate and exhibits high catalytic activity as well as excellent stability, which gives it the potential to be used on an industrial scale, and maybe opens a way for the catalytic oxidation reaction via inorganic-ligand coordinated iron catalysis.

Immobilization of [MoO2(acac)2] on surface of hydroxyapatite nanoparticles: A heterogeneous and reusable catalyst for olefin epoxidation reactions

AbstractA new heterogeneous catalyst was prepared by grafting [MoO2(acac)2] on the hydroxyapatite (HAP) nanoparticle surfaces. The resulting catalyst, [MoO2(acac)]@HAP, was characterized by the powder X‐ray diffraction, FT‐IR spectroscopy, inductively coupled plasma/atomic emission spectroscopy, field emission scanning electron microscopy, energy‐dispersive X‐ray analysis, thermogravimetery analysis, and transmission electron microscopy techniques. The results obtained confirmed that the catalyst could be successfully used for the efficient epoxidation of olefins with tert‐butyl hydrogen peroxide in 1,2‐dichloroethane as the solvent. This heterogeneous catalyst could be reused for several times without a significant loss in its catalytic activity and with no significant reduction in the reaction yield. This novel material showed a great catalytic performance, and the reactions carried out using this catalyst showed a good‐to‐excellent yield, high purity of the desired products, and a short reaction time.

FeNi3@SiO2 nanoparticles: an efficient and selective heterogeneous catalyst for the epoxidation of olefins and the oxidation of sulfides in the presence of meta-chloroperoxybenzoic acid at room temperature

In this article, FeNi3 nanoparticles were coated by silica and applied for green, inexpensive, selective and efficient epoxidation of alkenes as well as oxidation of sulfides to the corresponding sulfoxides. The oxidation was performed over FeNi3@SiO2 nanoparticles in the presence of meta-chloroperoxybenzoic acid as an oxygen source in dichloromethane at room temperature. High reaction conversion as well as oxidation product selectivity were obtained for both sulfoxide or epoxide compounds. The properties of the catalyst were studied by transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometer instruments. The heterogeneous nanocatalyst was magnetically recovered and could be reused in at least five consecutive runs without noticeable reactivity loss.

Self‐assembled metalloporphyrins–inorganic hybrid flowers and their application to efficient epoxidation of olefins

AbstractBACKGROUNDVarious proteins or enzymes were employed as organic components to form hybrid flowers, and they exhibited excellent properties in catalysis, adsorption, and sensing. However, there is no previous report of metalloporphyrins‐based hybrid flowers. Based on the importance of metalloporphyrins in catalytic reactions, metalloporphyrins–copper phosphate hybrid flowers were prepared and their catalytic performance in epoxidation reactions was evaluated.RESULTSThe composition, morphology, and crystallite structure of the hybrid flowers strongly depended on the incubation time (0.1–72 h) and concentration of metalloporphyrins in the mother liquor (0–47 µg mL−1). In comparison with the free metalloporphyrins, the hybrid flowers exhibited enhanced stability without any decrease in the catalytic activity. Moreover, the activity was linearly correlated with the surface content of metalloporphyrins which indicated that the metalloporphyrins on the surface were the key active species. Furthermore, the hybrid flowers showed good compatibility with a wide range of solvents and substrates.CONCLUSIONThe mechanism of formation of the hybrid flowers was proposed that involves four major successive steps: coordination, nucleation, formation, and growth. The catalytic results suggest that well‐designed hybrid materials with hierarchical nano‐structures and metalloporphyrins as organic component would be potential candidates for industrial catalysis applications. © 2017 Society of Chemical Industry

Highly efficient epoxidation of alkenes with m-chloroperbenzoic acid catalyzed by nanomagnetic Co(III)@Fe3O4/SiO2 salen complex

A new type of heterogeneous Co(III) complex was synthesized by covalent grafting of homogeneous Co(III) salen complex onto the surface of Fe3O4/SiO2 nanoparticle (NP). The heterogeneous nanocatalyst was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), atomic absorption spectroscopy (AAS), vibrating sample magnetometer (VSM) and nitrogen adsorption–desorption isotherm (BET). The catalytic activity was investigated for the epoxidation of alkenes using m-chloroperbenzoic acid as oxidant at room temperature and the corresponding epoxide was achieved with excellent yields and selectivity. In addition, the effect of axial ligand was studied on the epoxidation reaction and pyridine N-oxide (PNO) was chosen as an excellent axial ligand in dichloromethane. Furthermore, the heterogeneous catalyst showed good stability and the magnetic properties (which made possible the easy recovery of catalyst with external magnet) without significant decrease in the activity in the epoxidation reaction.

Recyclable Pd supported catalysts with low loading for efficient epoxidation of olefins at ambient conditions

Epoxides are a kind of useful synthetic intermediates. This work reports that activated carbon-supported Pd nanoparticles (Pd/C) efficiently catalyzed cyclohexene epoxidation in the presence of molecular oxygen and isobutyraldehyde with 91.5% conversion, 95.6% selectivity to cyclohexene oxide, ~400h−1 activity and excellent stability for at least 5 catalytic runs. The epoxidation was examined on Pd catalysts supported on seven supports, and Pd/C exhibited superior catalytic performance possibly due to the inert support surface. The epoxidation reaction on Pd/C is via radical intermediate. Pd/C is also applicable to catalyze other olefins epoxidation.

Graphene oxide nanosheets supported manganese(III) porphyrin: a highly efficient and reusable biomimetic catalyst for epoxidation of alkenes with sodium periodate

Efficient epoxidation of alkenes catalyzed by tetrakis(p-aminophenyl)porphyrinatomanganese(III) chloride, [Mn(TNH2PP)Cl], supported on graphene oxide nanosheets, is reported. The catalyst, [Mn(TNH2PP)Cl]@GO, was prepared by covalent attachment of amino groups of porphyrin to carboxylic acid groups of GO. This new heterogenized catalyst was characterized by ICP, FT-IR and diffuse reflectance UV–vis spectroscopies, scanning electron microscopy and transmission electron microscopy. This catalyst was applied as an efficient and reusable catalyst in the epoxidation of alkenes with NaIO4 at room temperature, in the presence of imidazole as axial ligand. The most noteworthy advantage of [Mn(TNH2PP)Cl]@GO is its high reusability in the oxidation reactions, in which the catalyst was reused several times without significant loss of its catalytic activity.

Catalytic activity of multi-wall carbon nanotube supported manganese (III) porphyrin: an efficient, selective and reusable catalyst for oxidation of alkenes and alkanes with urea–hydrogen peroxide

ABSTRACTManganese complex of meso-tetrakis(4-hydroxyphenyl)porphyrin immobilised onto functionalised multi-wall carbon nanotubes (MWCNT) has been synthesised and characterised by elemental analysis, Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis) spectroscopy, powder X-ray diffraction and scanning electron microscopy. This catalyst, [Mn(THPP)OAc@MWCNT], was successfully applied for efficient epoxidation of alkenes and alkanes with urea–hydrogen peroxide. The role of the stoichiometric amounts of the acetic anhydride as an oxidant activator which introduce in situ peracetic acid has been discussed. This heterogeneous catalyst was highly reusable in the oxidation reactions and reused several times without significant loss of its catalytic activity.

A Phytic Acid Induced Super-Amphiphilic Multifunctional 3D Graphene-Based Foam.

Surfaces with super-amphiphilicity have attracted tremendous interest for fundamental and applied research owing to their special affinity to both oil and water. It is generally believed that 3D graphenes are monoliths with strongly hydrophobic surfaces. Herein, we demonstrate the preparation of a 3D super-amphiphilic (that is, highly hydrophilic and oleophilic) graphene-based assembly in a single-step using phytic acid acting as both a gelator and as a dopant. The product shows both hydrophilic and oleophilic intelligence, and this overcomes the drawbacks of presently known hydrophobic 3D graphene assemblies. It can absorb water and oils alike. The utility of the new material was demonstrated by designing a heterogeneous catalytic system through incorporation of a zeolite into its amphiphilic 3D scaffold. The resulting bulk network was shown to enable efficient epoxidation of alkenes without prior addition of a co-solvent or stirring. This catalyst also can be recovered and re-used, thereby providing a clean catalytic process with simplified work-up.