Showing papers on "Styrene oxide published in 2021"

High-Loading Single-Atomic-Site Silver Catalysts with an Ag1–C2N1 Structure Showing Superior Performance for Epoxidation of Styrene

Abstract: Epoxidation is an efficient chemical process for manufacturing styrene oxide; however, it remains a huge challenge to develop cost-effective and environment-friendly catalysts for facilitating this...

A High-Performance Zinc-Organic Framework with Accessible Open Metal Sites Catalyzes CO2 and Styrene Oxide into Styrene Carbonate under Mild Conditions

Abstract: A new tetratopic bridging ligand 1,1′-(propane-1,3-diyl)bis(1H-pyrazole-3,5-dicarboxylic acid) (PDC) with functional pyrazole groups was designed and used for reacting with environmentally friendly

Fixation of CO2 into Cyclic Carbonates by Halogen-Bonding Catalysis.

Abstract: Halogen bonding, parallel to hydrogen bonding, was introduced into the catalytic cycloaddition of carbon dioxide into epoxide (CCE) reactions. A series of halogen-bond donor (XBD) catalysts of N-iodopyridinium halide featured with N-I bond were synthesized and evaluated in CCE reactions. The optimal XBD catalyst, 4-(dimethylamino)-N-iodopyridinium bromide ([DMAPI]Br), under screened conditions at 100 °C, ambient pressure, and 1 mol % catalyst loading, realized 93 % conversion of styrene oxide into cyclic carbonate in 6 h. The substrate scope was successfully extended with excellent yields (mostly ≥93 %) and quantitative selectivity (more than 99 %). 1 H NMR spectroscopy of the catalyst [DMAPI]Br on substrate epoxide certified that the N-I bond directly coordinated with the epoxide oxygen. A plausible mechanism of halogen-bonding catalysis was proposed, in which the DMAPI cation functioned as halogen-bond donor to activate the epoxide, and the counter anion bromide attacked the methylene carbon to initiate the ring-opening of the epoxide. CCE reactions promoted by N-iodopyridinium halide, exemplify a first case of halogen-bonding catalysis in epoxide activation and CO2 transformation.

Controllable Generation of Reactive Oxygen Species on Cyano-Group-Modified Carbon Nitride for Selective Epoxidation of Styrene.

Abstract: Summary The controlled generation of reactive oxygen species (ROS) to selectively epoxidize styrene is a grand challenge Herein, cyano-group-modified carbon nitrides (CNCYx and CN-Ty) are prepared, and the catalysts show better performance in regulating ROS and producing styrene oxide than the cyano-free sample The in situ diffuse reflectance infrared and density functional theory calculation results reveal that the cyano group acts as the adsorption and activation site of oxygen X-ray photoelectron spectroscopy and NMR spectrum results confirm that the cyano group bonds with the intact heptazine ring This unique structure could inhibit H2O2 and ⋅OH formation, resulting in high selectivity of styrene oxide Furthermore, high catalytic activity is still achieved when the system scales up to 27 L with 100 g styrene under solar light irradiation The strategy of cyano group modification gives a new insight into regulating spatial configuration for tuning the utilization of oxygen-active species and shows potential applications in industry

Kinetic study for styrene carbonate synthesis via CO2 cycloaddition to styrene oxide using silica-supported pyrrolidinopyridinium iodide catalyst

Abstract: Reaction kinetics for heterogeneous catalysis of styrene carbonate (SC) synthesis via CO2 cycloaddition to styrene oxide (SO) using silica-supported pyrrolidinopyridinium iodide (SiO2-PPI) catalyst has been investigated. The results obtained from the mixing study and theoretical analysis based on Thiele modulus (

Imidazolium-based deep eutectic solvents as multifunctional catalysts for multisite synergistic activation of epoxides and ambient synthesis of cyclic carbonates

Abstract: Novel imidazolium-based deep eutectic solvents were facilely synthesized and characterized by TGA, DSC, FT-IR, and NMR techniques. Various imidazolium salts and aromatic compounds containing active hydrogens were applied as HBAs and HBDs respectively for efficient cycloaddition of CO2 with styrene oxide under ambient conditions. The optimized [C1C2Im]I/m-DHB (1-ethyl-3-methylimidazolium iodide/m-dihydroxybenzene) DES with the molar ratio of 2:1 exhibited excellent catalytic activity at room temperature and 0.1 MPa CO2 pressure without cocatalyst, metal, and solvent. Moreover, the effects of reaction parameters, substrate scope, and catalyst recovery were studied in detail. Based on the results, the plausible reaction mechanism on the multisite synergistic activation of the epoxide by the hydrogen bonds involved with both the OH in m-DHB and C2-H in [C1C2Im]I was proposed. Finally, the reaction kinetics was studied and the cycloaddition reaction was accorded with the pseudo-first-order reaction kinetic model.

MCM-41 modified heterogeneous catalysts from rice husk for selective oxidation of styrene into benzaldehyde

Abstract: This study examined the preparation of MCM-41, Ni-MCM-41 and Co-MCM-41 from silica extracted from rice husk ash (RHA) via sol–gel technique. The materials were characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), Diffuse reflectance UV–Vis (DR/UV–Vis),Energy Dispersive X-ray Spectrometry (EDX), N 2 adsorption–desorption and NH3 TPD. XRD and TEM analyses showed reduction in the long range order upon the introduction of heteroatoms into MCM-41 framework. Successful substitution of Si 4 + with metal cations was verified by the shifting in the siloxane (Si-O-Si) bond. Presence of nickel phyllosilicates was evidenced from the FT-IR and DR/UV–Vis investigations. Mesoporous behavior with capillary condensation was unchanged even after the incorporation of Ni and Co species into the MCM-41 matrix. MCM-41 and modified MCM-41 catalysts were evaluated in the liquid-phase oxidation of styrene for 4 h under the influence of reaction parameters such as reaction temperature, catalyst loading, types of solvent and molar ratio of styrene : H2O2. Under the optimum condition of 343 K, 0.20 g catalyst, 1:4 molar ratios and DMF as the reaction medium, the activity was found to increase following the trend: Ni-MCM-41 (79.9%) >Co-MCM-41(56.6%) > MCM-41 (40.7%). Benzaldehyde was the sole product over Ni-MCM-41 and Co-MCM-41 while MCM-41 gave benzaldehyde (96.0%) and styrene oxide (4.0%). Surface characteristics and TPD acidity strength was found to govern the catalysis. Negligible leaching (0.448 ppm) and exceptional activity during successive reruns demonstrates that Ni-MCM-41 was beyond doubt, heterogeneous in nature. This research signifies a successful conversion of waste biomass into value added products.

Polyoxometalate-modified reduced graphene oxide foam as a monolith reactor for efficient flow catalysis of epoxide ring-opening reactions

Abstract: Continuous flow catalysis has been attracting significant interest due to its remarkable advantages over traditional batch reactions. In this work, a facile and broad-spectrum hydrothermal approach has been developed to construct polyoxometalate-modified reduced graphene oxide (POM@rGO) foam, which worked as a monolith reactor for efficient continuous flow catalysis of epoxide ring-opening reactions. The porous structures of rGO foam allow the high dispersion of the POM catalyst onto the substrate through electrostatic interactions. Specifically, a phosphotungstic acid (H3PW12O40, denoted as PW12)-modified rGO (PW12@rGO) monolith reactor exhibits remarkable catalytic activity and durability towards epoxide ring-opening reactions with alcohols, achieving 99% conversion and 92% selectivity for the methanolysis product in 10 min under ambient conditions without stirring. Notably, while coupling with a micro-injection pump, such PW12@rGO foam can work as an efficient continuous flow reactor towards methanolysis of styrene oxide for 38 h with 99% conversion and over 90% selectivity, reaching a turnover number (TON) as high as 28 044.

Enhancing catalytic epoxide ring-opening selectivity using surface-modified Ti3C2Tx MXenes

Abstract: TKS was supported by the NWO TOP-PUNT Catalysis in Confined Spaces (Grant 718.015.004). EVRF and ASE acknowledge financial support by MINECO (Spain) through the projects MAT2017-86992-R and MAT2016-80285-P. VN and MWB thank NSF DMR 1740795 for financial support.

Lanthanide metal–organic frameworks for catalytic oxidation of olefins

Abstract: Two isostructural lanthanide metal–organic frameworks (Ln-MOF-589, Ln = La3+, Ce3+), constructed from a tetratopic linker, benzoimidephenanthroline tetracarboxylic acid (H4BIPA-TC), have been solvothermally synthesized and characterized. These Ln-MOF-589 materials consist of Lewis acid [Ln2(-COO)6(-COOH)2(H2O)6] units and a naphthalene diimide core, which exhibited promising catalytic activity for the oxidation of olefins. Among them, Ce-MOF-589 exhibited outstanding performance with high conversions of styrene and cyclohexene (94 and 90%, respectively), and good selectivities towards styrene oxide and 2-cyclohexen-1-one (85, and 95%, respectively). Notably, the catalytic activity of Ce-MOF-589 outperformed that of homogeneous and heterogeneous catalysts, and representative MOFs. Also, Ce-MOF-589 can be recycled for at least up to six cycles with no significant loss of catalytic performance.

Three-dimensional commercial-sponge-derived Co3O4@C catalysts for effective treatments of organic contaminants

Abstract: This study concerns an application of spongin-based scaffolds of commercial sponge origin as a naturally structured precursor of carbon material. Further functionalization with cobalt via a simple sorption-reduction method resulted in the preparation of novel catalysts tested in oxidation-reduction reactions. The structure and chemical composition of the prepared materials were investigated in detail, demonstrating the presence of carbonized fibers tightly covered with a metal-containing phase mainly composed of Co3O4. The fibrous structure with open porous canals provides good accessibility for substrates to the surface of the catalysts. Biocarbon material obtained at 600 °C exhibited good catalytic ability in the oxidation of styrene (with high selectivity for the formation of styrene oxide) and rhodamine B compared with other prepared catalysts and biocarbons. Interestingly, all of the prepared materials exhibit favorable activity in the reduction of 4-nitrophenol. A reusability study showed good activity even after the fifth catalytic cycle in both oxidation and reduction reactions. The study proved the adaptability of spongin-based scaffolds to prepare biocarbons with high potential to be used as a support for various catalytic applications.

Insights into the Solubility of Carbon Dioxide in Grafted Mesoporous Silica for the Catalytic Synthesis of Cyclic Carbonates by Nanoconfinement.

Abstract: Gas solubility can go beyond classical bulk-liquid Henry's law saturation under the nanoconfinement of a liquid phase. This concept establishes the foundation of the current study for developing a novel catalytic system for transformation of carbon dioxide to cyclic carbonates at mild conditions with major emphasis on application for CO2 capture and utilization. A series of mesoporous silica-based supports of various pore sizes and shapes grafted with a quaternary ammonium salt is synthesized and characterized. CO2 sorption in styrene oxide, either in bulk or nanoconfined state, as well as catalytic reactivity for CO2 transformation into styrene carbonate, are experimentally evaluated. The family of mesoporous catalysts with aligned cylindrical pores (MCM-41 and SBA-15) with pore sizes ranging from 3.5 to 9 nm exhibit enhanced sorption of CO2 in nanoconfined styrene oxide with maximum sorption capacity taking place in MCM-41 with the smallest pore size. The catalysts with interconnected cylindrical pores (KIT-6) with pore sizes ranging from 4.5 to 8.7 nm showed CO2 solubilities almost equal to the bulk solubility of styrene oxide. Monte Carlo simulations revealed that the oversolubility in styrene oxide confined complex is directly related to the density of adsorbed solvent in the nanopore, which is less than its bulk density. Catalytic reactivities correlate with CO2 sorption enhancement, showing higher turnover frequencies for catalysts having higher CO2 sorption capacity. The turnover frequency is increased by a factor of 7.5 for grafted MCM-41 with the smallest pore size with nanoconfined styrene oxide in comparison to the homogeneous reaction implemented in bulk.

Copper(II) triflate catalyzed three-component reaction for the synthesis of 2,3-diarylquinoline derivatives using aryl amines, aryl aldehydes and styrene oxides

Abstract: An efficient and expedient synthetic protocol is reported for the synthesis of 2,3-diarylquinoline derivatives from readily available aryl amines, aryl aldehydes and styrene oxides using 10 mol% copper(II) triflate by employing three-component reaction. This approach involves the reaction between the in situ generated imine (derived from the aryl amine and aryl aldehyde) and styrene oxide, which enables the formation of the desired products. The present method has several advantages such as high atom-economy, high regioselectivity, easy handling, consecutive one C–N and two C–C bond formation, shorter reaction time and broader substrate scope with good yields.

Study of the Cycloaddition of CO2 with Styrene Oxide Over Six-Connected spn Topology MOFs (Zr, Hf) at Room Temperature.

Abstract: A series of MOFs with a 6-connected spn topology were synthesized (MOF-808-(Zr, Hf), PCN-777-(Zr, Hf), MOF-818-(Zr, Hf)). Through the in situ DRIFTS of NH3 adsorption-desorption, we found that the activated catalyst mainly contains Lewis acid sites. The effects of different organic ligands on the Lewis acid of the Zr6 cluster were analyzed by XPS and NH3 -TPD, and the relative Lewis acidity of the same metal was obtained: PCN-777>MOF-808>MOF-818. In the Py-FTIR results, we confirmed that MOF-818 has a higher acid site density. In the activity test, MOFs with mesoporous structure showed better catalytic activity under normal temperature and pressure. Among them, MOF-818 can still maintain a high degree of crystallinity after catalysis. Finally, we use density functional theory to propose the mechanism of the cycloaddition reaction of carbon dioxide and styrene oxide. The results show that the metal is coordinated with styrene oxide and halogens attack the β carbon of the epoxide.

Zeolite-mediated production of cyclic organic carbonates: reaction of CO2 with styrene oxide on zeolite Y impregnated with metal halides

Abstract: Zeolites LiY, NaY, KY and ZnY were impregnated with small amounts of the corresponding metal halides (chloride, bromide and iodide) and tested as catalysts for the carboxylation of styrene oxide with CO2. The KI/KY system was tested at 100 °C and 50 bar and yielded 100% of styrene carbonate, by 1H NMR, within 6 h, whereas KI alone required 15 h to achieve the same yield. The reaction occurs inside the zeolite pores, with the metal cations acting as Lewis acidic centers and the impregnated halides as nucleophiles. Theoretical calculations indicated that chlorides are better stabilized within the zeolite cage than iodides, explaining the reactivity order and suggesting a solvent-like behavior of the zeolite structure.

Epoxidation of alkene using bi-functional metal oxide supported SBA-16 catalyst

Abstract: Three dimensional (3D) cubic cage like Im3m mesoporous SBA-16 was synthesized by one pot hydrothermal method using Pluronic F127 as structure directing agent and Tetraethylorthosilicate as silica precursor. Different weight percentages (1 wt%, 3 wt% and 5 wt%) of manganese nitrate tetrahydrate were homogeneously mixed with the same weight percentages of ammonium tungsten oxide hydrate respectively and dispersed on SBA-16 by incipient wet impregnation method. Structural identification and the particle arrangement for as-synthesized SBA-16 materials were analyzed using low and high angle X-ray diffraction. Surface area, pore-diameter, pore volume and pore size distribution were observed using the N2 adsorption isotherm technique with H2 hysteresis loop. The topography of the catalyst was characterized by TEM. The chemical valence state and elemental composition were characterized by high-resolution XPS respectively. The thermal stability of the catalyst was characterized by Thermogravimetric analysis. The synthesized materials MnWO4/SBA-16 were tested for epoxidation of styrene with environmentally benign TBHP as an oxidant. Various parametric investigations were performed and reported. From the above investigation, it is inferred that the major product of styrene oxide was obtained with maximum selectivity of about 75% using MnWO4 (3 wt%)/SBA-16.

Characterization of the Glutathione S-Transferases Involved in Styrene Degradation in Gordonia rubripertincta CWB2.

Abstract: The glutathione S-transferases carried on the plasmid for the styrene-specific degradation pathway in the Actinobacterium Gordonia rubripertincta CWB2 were heterologously expressed in Escherichia coli. Both enzymes were purified via affinity chromatography and subjected to activity investigations. StyI and StyJ displayed activity toward the commonly used glutathione S-transferase model substrate 1-chloro-2,4-dinitrobenzene (CDNB) with Km values of 0.0682 ± 0.0074 and 2.0281 ± 0.1301 mM and Vmax values of 0.0158 ± 0.0002 and 0.348 ± 0.008 U mg-1 for StyI and StyJ, respectively. The conversion of the natural substrate styrene oxide to the intermediate (1-phenyl-2-hydroxyethyl)glutathione was detected for StyI with 48.3 ± 2.9 U mg-1. This elucidates one more step in the not yet fully resolved styrene-specific degradation pathway of Gordonia rubripertincta CWB2. A characterization of both purified enzymes adds more insight into the scarce research field of actinobacterial glutathione S-transferases. Moreover, a sequence and phylogenetic analysis puts both enzymes into a physiological and evolutionary context. IMPORTANCE Styrene is a toxic compound that is used at a large scale by industry for plastic production. Bacterial degradation of styrene is a possibility for bioremediation and pollution prevention. Intermediates of styrene derivatives degraded in the styrene-specific pathways are precursors for valuable chemical compounds. The pathway in Gordonia rubripertincta CWB2 has proven to accept a broader substrate range than other bacterial styrene degraders. The enzymes characterized in this study, distinguish CWB2s pathway from other known styrene degradation routes and thus might be the main key for its ability to produce ibuprofen from the respective styrene derivative. A biotechnological utilization of this cascade could lead to efficient and sustainable production of drugs, flavors, and fragrances. Moreover, research on glutathione metabolism in Actinobacteria is rare. Here, a characterization of two glutathione S-transferases of actinobacterial origin is presented, and the utilization of glutathione in the metabolism of an Actinobacterium is proven.

Syntheses, Characterization, and Application of Tridentate Phenoxyimino-Phenoxy Aluminum Complexes for the Coupling of Terminal Epoxide with CO2: From Binary System to Single Component Catalyst

Abstract: A series of binuclear aluminum complexes 1–3 supported by tridentate phenoxyimino-phenoxy ligands was synthesized and used as catalysts for the coupling reaction of terminal epoxide with carbon dioxide. The aluminum complex 1, which is catalytically inactive toward the coupling of epoxide with CO2 by itself, shows moderate activity in the presence of excess nucleophiles or organic bases at high temperature. In sharp contrast to complex 1, bifunctional complexes 2 and 3, which incorporate tertiary amine groups as the built-in nucleophile, are able to efficiently transform terminal epoxide with CO2 to corresponding cyclic carbonates as a sole product by themselves at 100 °C. The number of amine groups on the ligand skeleton and the reaction temperature exert a great influence on the catalytic activity. The bifunctional complexes 2 and 3 are also active at low carbon dioxide pressure such as 2 atm or atmospheric CO2 pressure. Kinetic studies of the coupling reactions of chloropropylene oxide/CO2 and styrene oxide/CO2 using bifunctional catalysts under atmospheric pressure of CO2 demonstrate that the coupling reaction has a first-order dependence on the concentration of the epoxide.