Showing papers on "Styrene oxide published in 2017"
TL;DR: In this article, the acid-base duality induced by boron doped carbon nitride (BCN) enables the coactivation of CO 2 and epoxide, and the reaction follows the Langmuir-Hinshelwood mechanism, where CO 2 is activated on the basic NH sites and SO is on the acidic −B(OH) 2 sites through a hydrogen bonding.
Abstract: The cycloaddition of CO 2 and epoxides to yield cyclic carbonate under solvent-free conditions is an eco-friendly way to utilize CO 2 in environmental science and green chemistry. In this paper, we report that boron doped carbon nitride (BCN) is highly active and selective for such reactions. BCN, especially if supported on mesoporous silica SBA-15 (i.e., B 0.1 CN/SBA-15), shows above 95% conversion and selectivity for cycloaddition of CO 2 and styrene oxide (SO) to yield styrene carbonate (SC), even under solvent-free conditions. That is mainly due to the acid-base duality induced by B doping, which enables the co-activation of CO 2 and epoxide. A mechanism based on acid-base duality is proposed, where CO 2 is activated on the basic >NH sites and SO is on the acidic −B(OH) 2 sites through a hydrogen bonding. The co-activated CO 2 and SO react with each other to yield the SC. Density functional theory (DFT) calculations were conducted to support the mechanism, which show that the co-adsorption of CO 2 and SO on BCN is energetically favorable and the reaction follows the Langmuir-Hinshelwood mechanism. The BCN with acid-base duality provides an option for cheap, green and efficient catalysts for CO 2 utilization.
134 citations
TL;DR: A β-diiminato-zinc-N(SiMe3)2 complex was synthesized and fully characterised, including an X-ray diffraction study as discussed by the authors.
Abstract: A β-diiminato–zinc–N(SiMe3)2 complex (1) was synthesised and fully characterised, including an X-ray diffraction study. The activity of catalyst 1 towards the coupling reaction of CO2 and various epoxides, including propylene oxide (PO), cyclohexene oxide (CHO), styrene oxide (SO), limonene oxide (LO), octene oxide (OO) and epichlorohydrin (ECH), was investigated. Terpolymerisation of CO2, PO and LO, as well as CO2, CHO and PO, was successfully realised, resulting in polymers with adjustable glass transition temperatures and transparencies. Reaction conditions such as temperature, pressure and catalyst concentration were varied to find the optimal reaction values, especially regarding LO/CO2. In situ IR experiments hinted that at 60 °C and a critical LO concentration, polymerisation and depolymerisation are in an equilibrium (ceiling effect). Pressurising catalyst 1 with carbon dioxide resulted in a dimeric catalyst (2) with a OSiMe3 group as a new initiator. Homopolymerisation of different epoxides was carried out in order to explain the reactivity concerning copolymerisation reaction of CO2 and epoxides.
77 citations
TL;DR: The best catalytic performance was obtained for MIL-100(Cr) in combination with EMIMBr ionic liquid, which gave very high styrene carbonate yield and complete selectivity after 18 h of reaction at mild temperature (60 °C).
Abstract: Metal–organic frameworks (MOFs) with accessible Lewis acid sites are finding increasing application in the field of heterogeneous catalysis. However, the structural instability of MOFs when they are exposed to high temperature and/or high pressure often limits their applicability. In this study, two strategies were applied to achieve a MOF catalyst with high stability, activity and selectivity in the reaction of CO2 with styrene oxide to produce styrene carbonate. In the first approach, a MOF with linkers with high connectivity as MIL-100(Cr) was studied, leading to promising activity and recyclability in consecutive catalytic runs without loss of activity. In the second strategy, a MOF with linkers with lower connectivity but with encapsulated Keggin phosphotungstic acid (MIL-101(Cr)[PTA]) was prepared. However, the activity of this catalyst decreased upon reuse as a consequence of deterioration of the MOF. Further investigations were dedicated to the enhancement of the catalytic performance of MIL-100 and included the variation of the metal centre as well as the type and loading of organic salt acting as nucleophile source. This allowed tuning the nature of the organic halide to the specific porous structure of MIL-100(Cr) to prevent diffusion limitations. The best catalytic performance was obtained for MIL-100(Cr) in combination with EMIMBr ionic liquid, which gave very high styrene carbonate yield (94 %) with complete selectivity after 18 h of reaction at mild temperature (60 °C).
70 citations
TL;DR: In this article, a new efficient heterogeneous catalyst was introduced for the epoxidation of styrene, which was obtained from deposition of gold nanoparticles on the cellulose aerogel.
Abstract: A new efficient heterogeneous catalyst was introduced for the epoxidation of styrene. The catalyst was obtained from deposition of gold nanoparticles on the cellulose aerogel. The catalyst was characterized with XRD, TGA, EDX, BET, FAAS and SEM. High yield and excellent selectivity were achieved for the epoxidation of styrene in solvent-free conditions at room temperature using H2O2 as a green oxidant during 1 h. The reaction has some advantages such as solvent-free and mild reaction conditions, low catalyst loading, high yield, excellent selectivity, green oxidant and short reaction duration. In addition, the catalyst is recyclable and applicable for six times without decrease in yield.
35 citations
TL;DR: A structure-performance relationship study indicated that copper(ii) in CuO was the active site for the epoxidation and oxidation of Styrene, and that CuII of rich electronic density favored the improvement of selectivity of styrene oxide.
Abstract: A highly dispersed CuO catalyst was prepared by the deposition–precipitation method and evaluated for the catalytic epoxidation of styrene with tert-butyl hydroperoxide (TBHP) as the oxidant under solvent acetonitrile conditions. Compared with MgAl hydrotalcite (MgAl-HT)-, MgO-, TiO2-, C-, and MCM-22-supported catalysts, CuO/CoAl-HT exhibited preferable activity and selectivity towards styrene oxide (72% selectivity at 99.5% styrene conversion) due to its high dispersion of CuO and surface area of Cu. The improved dispersion of CuO/CoAl-HT could be ascribed to the nature of HT support, especially the synergistic effect of acidic and basic sites on the surface, which facilitated the formation of highly dispersed CuO species. A structure–performance relationship study indicated that copper(II) in CuO was the active site for the epoxidation and oxidation of styrene, and that CuII of rich electronic density favored the improvement of selectivity of styrene oxide. Based on these results, a reaction mechanism was proposed. Moreover, the preferred catalytic performance of CuO/CoAl-HT could be maintained in five reused cycles.
34 citations
TL;DR: In this paper, a simple method for preparation of a novel nanocatalyst, composed of Ag nanoparticles, mesoporous TiO 2 and CoFe 2 O 4 nanoparticle, has been reported for three important reactions (i) epoxidation of styrene, (ii) reduction of 4-nitrophenol (4-NP) and (iii) photocatalytic degradation of Methylene Blue dye).
33 citations
TL;DR: In this article, a novel stereoselective interaction between two opposite-configuration isotactic polymers was first found in the blend of equivalent (R)- and (S) polymers, and the corresponding isotactic 3-chlorostyrene oxide/CO2 copolymer appears amorphous feature, possessing a Tg of 82.1 °C.
Abstract: Highly regioselective copolymerization of CO2 and enantiopure terminal epoxides with an electron-withdrawing group, styrene oxide and its derivatives, was achieved by the use of multichiral salenCo(III) complex-based catalyst systems, in which epoxide ring-opening predominantly occurred at methylene C–O bond, affording isotactic CO2 copolymers with up to 98% head-to-tail connectivity and 97% enantioselectivity. The stereoregular poly(styrene carbonate) with 98% isotacticity is a typical semicrystalline material, possessing a melting temperature (Tm) of 137.3 °C and an enhanced glass transition temperature (Tg) of 101.2 °C. The isotactic 3-methoxystyrene oxide/CO2 copolymer is also a semicrystalline polymer with a Tm of around 90 °C, while the corresponding isotactic 3-chlorostyrene oxide/CO2 copolymer appears amorphous feature, possessing a Tg of 82.1 °C. Notably, a novel stereoselective interaction between two opposite-configuration isotactic polymers was first found in the blend of equivalent (R)- and (...
32 citations
TL;DR: A chiral MnIII-porphyrin complex covalently bonded with mesoporous SBA-15 (SBA15-[Mn(TCPP-R∗)Cl]) was synthesized and fully characterized in this article.
31 citations
TL;DR: In this paper, the first investigation of cobalt corrole catalyzed oxidation of alkene was conducted by using styrene as substrate and the best yield was obtained in acetonitrile solvent in the air with TBHP oxidant (96% yield based on oxidant, up to 96 TON).
Abstract: Four cobalt (III) corroles bearing different number of pentafluorophenyl and phenyl groups were synthesized and characterized by elemental analysis, HR-MS, UV–vis, NMR, XPS as well as cyclic voltammetry. The first investigation of cobalt corrole catalyzed oxidation of alkene was conducted by using styrene as substrate. The best yield was obtained in acetonitrile solvent in the air with TBHP oxidant (96% yield based on oxidant, up to 96 TON). Benzaldehyde was detected as the main product by using PhI(OAc)2, TBHP, KHSO5, PhIO as oxidants. In contrast, styrene oxide was found to be the major product when using m-CPBA oxidant. Nearly no products could be found by using H2O2 oxidant. Possible catalytic oxidation pathway was also discussed based on the obsewrvations of UV–vis changes of the ctatalytic system in the absence of substrate and in-situ HR-MS.
25 citations
TL;DR: In this article, the authors demonstrated the development of cooperative catalyst whereby Lewis acid/base species and nucleophilic parts are immobilized in the pores of a polyamide-imide (PAI) hollow fiber support.
Abstract: In this study, development of cooperative catalyst is demonstrated whereby Lewis acid/base species and nucleophilic parts are immobilized in the pores of a polyamide-imide (PAI) hollow fiber support. The highly solvent-stable and porous Br/APS-grafted ZrO2-PAI hollow fiber (Br/APS/Zr-PAIHF) catalyst was created by crosslinking of bare ZrO2-PAIHF polymer with 3-aminopropyltrimethoxysilane (APS) followed by alkylation with 1,2-dibromoethane at 110 °C. This bifunctional catalyst consists of a porous ZrO2-PAIHF polymer crosslinked with APS that was further immobilized with nucleophilic bromide ions. Porous ZrO2-PAIHF provides a physical barrier to prevent cooperative Lewis acid/base species and nucleophilic parts movement, aggregation, and detachment from the support into the product stream. The performance of Br/APS/Zr-PAIHFs as heterogeneous catalyst was investigated for the reaction of carbon dioxide (CO2) with styrene oxide (SO) which leads to the formation of styrene carbonate (SC). The influence of various reaction parameters including reaction temperature, reaction time, solvents, and CO2 pressure were systematically investigated in detail. Our results indicated that the synergistic cooperative effect of nucleophilic bromide ion (Br−) and Lewis acid/base species on PAIHF supports leads to a maximum SC selectivity of 99.1%. Additionally, SO conversion of 100% and excellent SC selectivity of 98% were obtained over Br/APS/Zr-PAI-HF catalyst.
23 citations
TL;DR: In this paper, a series of amidooxazolinate zinc complexes were used as highly active catalysts for the ring-opening copolymerization of styrene oxide and cyclic anhydrides.
Abstract: Polyesters have been widely applied owing to their biodegradability and biocompatibility. Recently, catalytic ring-opening copolymerization of cyclic anhydrides and epoxides has emerged as an effective approach for the synthesis of polyesters. Herein, we report a series of amido–oxazolinate zinc complexes as highly active catalysts for the ring-opening copolymerization of styrene oxide and cyclic anhydrides. Turnover frequencies up to 4000 h−1 were achieved in the reaction of styrene oxide and maleic anhydride. Analysis of the end groups provides a useful probe for the preference at the electron-poor methine site of styrene oxide for the ring-opening process.
TL;DR: In this paper, the structure and morphology of HKUST-1@SiO2 were characterized by X-Ray diffraction, scanning electron microscopy and low-temperature nitrogen adsorption.
Abstract: HKUST-1@silica aerogel composite pellets (HKUST-1@SiO2) were prepared by the coupled sol–gel and water-in-oil emulsion method using supercritical CO2 drying. The structure and morphology of HKUST-1@SiO2 were characterized by X-Ray diffraction, scanning electron microscopy and low-temperature nitrogen adsorption. According to these data, the composite represents physically dispersed micron-sized domains of HKUST-1 in the silica aerogel pellets. It was shown that the HKUST-1@SiO2 pellets can be used as a catalyst for isomerization of styrene oxide to phenyl acetaldehyde in a continuous flow reactor.
TL;DR: In this article, a magnetic nanocomposite catalyst with Co 3 O 4 nanoparticles immobilized on magnetic N-doped graphene was used for the epoxidation of alkenes to the corresponding epoxides.
TL;DR: In this paper, a series of g-C3N4 nanosheets were synthesized by thermal oxidation with long time heating and etching, and they showed a superior catalytic performance for the epoxidation of styrene to styrene oxide.
Abstract: A series of g-C3N4 nanosheets were synthesized by thermal oxidation with long time heating and etching. With an increase in heating time from 1.0 to 3.0 h, the g-C3N4 nanosheet was obtained with a thinner layer thickness, larger BET surface area and higher graphic nitrogen ratio. As a metal-free heterogeneous catalyst, the g-C3N4 NS-3 h nanosheets show a superior catalytic performance for the epoxidation of styrene to styrene oxide than that of the bulk g-C3N4 and other recently reported metal-free materials. The higher activity of the g-C3N4 NS-3 h synthesized by long time thermal oxidative etching might be ascribed to the enlarged specific surface, pore volume and higher graphic nitrogen ratio with the loose and soft laminar morphology. The graphitic nitrogen species play a key role in the catalytic reaction based on a good linear correlation between the content of these species and the activity results. The g-C3N4 nanosheets are very stable and can be reused 5 times without obvious loss of catalytic activity.
TL;DR: In this paper, a novel EH from Phaseolus vulgaris, PvEH2, was discovered based on the computer-aided analysis, and its encoding gene was cloned and expressed in E. coli Rossetta (DE3).
TL;DR: In this paper, the morphology effect of Zr-doped CeO2 was studied in terms of their activities in the selective oxidation of styrene to styrene oxide using tert-butyl hydroperoxide as the oxidant.
TL;DR: In this article, a terbium-organic framework (Tb-MOF) was used as a heterogeneous Lewis acid catalyst for the synthesis of β-amino alcohols.
Abstract: A terbium–organic framework (Tb-MOF) was prepared using a previously reported procedure. Tb-MOF was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction and surface area analysis. Tb-MOF was employed as a heterogeneous Lewis acid catalyst for the synthesis of β-aminoalcohols. Also, the effect of ultrasonic irradiation was examined in the catalytic aminolysis of styrene oxide. The reaction conditions were optimized by variation of reaction time, catalyst concentration and solvent. A variety of β-aminoalcohols were synthesized and characterized. The Tb-MOF catalyst showed excellent selectivity and high yield for these transformations.
TL;DR: A highly efficient, simple and environmentally friendly synthesis of 3-arylquinolines has been developed in the presence of Al2O3/MeSO3H via one-pot reaction of anilines and styrene oxide.
Abstract: A highly efficient, simple and environmentally friendly synthesis of 3-arylquinolines has been developed in the presence of Al2O3/MeSO3H via one-pot reaction of anilines and styrene oxide. This methodology provides very rapid access to 3-arylquinolines in good to excellent yields under solvent-free conditions at room temperature in air.
TL;DR: A kinetic study showed that the cycloaddition of CO2 adsorbed on [Nb10 O28 ]6- with SO corresponds to the rate-determining step in the Eley-Rideal mechanism.
Abstract: The decaniobate cluster (TBA)6 [Nb10 O28 ] (TBA+ =tetrabutylammonium cation) was found to act as a Lewis base catalyst for fixation of carbon dioxide (CO2 ) to styrene oxide (SO). A kinetic study showed that the cycloaddition of CO2 adsorbed on [Nb10 O28 ]6- with SO corresponds to the rate-determining step in the Eley-Rideal mechanism. Density functional theory calculation predicted that CO2 on the corner and edge O atoms of [Nb10 O28 ]6- is negatively charged and thus activated for nucleophilic attack on SO.
TL;DR: In this paper, an emerging strategy to improve the performance of porous metal-organic framework (MOF) materials as heterogeneous catalysts is reported, leading to a novel composite based MOF material, PW11Fe@NH2-MIL-101(Fe), which is revealed to be a remarkable selective heterogeneous catalyst for the studied reaction (100% selectivity to the 2-phenylamino-2phenylethanol isomer) with significant robustness and recyclability.
Abstract: An emerging strategy to improve the performance of porous metal–organic framework (MOF) materials as heterogeneous catalysts is reported. The incorporation of the iron-substituted polyoxometalate (POM) TBA4[PW11Fe(H2O)O39] (PW11Fe) in porous MOF NH2-MIL-101(Fe), leading to a novel composite based MOF material, PW11Fe@NH2-MIL-101(Fe), was revealed to be a significant approach to increase the efficiency of the MOF material as a regioselective catalyst for the ring opening of styrene oxide with aniline. The conversion after 1 h of reaction using NH2-MIL-101(Fe) is 22% and increases to 100% when PW11Fe@NH2-MIL-101(Fe) is employed as catalyst. It is noteworthy that the catalytic performance of this composite material is also considerably better than that obtained with the respective physical mixture under similar conditions. Furthermore, PW11Fe@NH2-MIL-101(Fe) revealed to be a remarkable selective heterogeneous catalyst for the studied reaction (100% selectivity to the 2-phenylamino-2-phenylethanol isomer) with significant robustness and recyclability.
TL;DR: In this paper, the photochemical oxidation of styrene under UV-A irradiation in acetonitrile solution containing H2O2 was investigated in absence or in presence of TiO2 or ZnO.
Abstract: The photochemical oxidation of styrene under UV-A irradiation in acetonitrile solution containing H2O2 was investigated in absence or in presence of TiO2 or ZnO. The effects of the molar ratio H2O2/styrene and of the pH on the disappearance rate and on the selectivity into benzaldehyde and benzene oxide were investigated. Under H202/UV, a conversion of about 6% and a total selectivity into benzaldehyde was observed. In presence of TiO2 the conversion is multiply by 2 and styrene oxide was detected. However, its selectivity is only 10%. At basic pH, in presence of TiO2 or ZnO, the conversion of styrene are 47% and 60% respectively. A similar selectivity of styrene oxide (50%) was found for the both catalysts. However, in presence of TiO2 benzoic acid is formed with a selectivity of 20% whereas only benzaldehyde was found on ZnO. The impact of the nature of the catalyst and of the active species generated under irradiation were suggested for explaining the difference of reactivity observed. A mechanism of the formation of benzaldehyde and styrene oxide in absence or presence of photocatalyst and of NaOH was proposed.
TL;DR: In this article, the TiO 2 -SiO 2 composite aerogels were prepared via sol-gel synthesis followed by ambient pressure drying technology, and then hydrophobically modified via the surface silylation reaction.
TL;DR: In this article, the isomerization of styrene oxide to phenyl acetaldehyde was investigated over a series of TS-1 catalysts with different crystal sizes and post-treatment methods under a gas-phase atmosphere free of solvents.
TL;DR: Partially purified epoxide hydrolase enzyme isolated from red mung beans was used for the first time for enantioselective hydrolysis of ( R,S )-styrene oxide to ( R )-1-phenyl-1,2-ethanediol, and it was found that the optimal reaction temperature, buffer pH, and substrate concentration were 40 °C, 7.5 and 20 mM, respectively.
TL;DR: In this paper, the coke and deactivation behavior of ZSM-5 in the isomerization of styrene oxide to phenylacetaldehyde was investigated under gas-phase free of solvents.
TL;DR: In this article, the impacts of reaction parameters including catalyst amount, initial volume ratio of solvent and temperature on styrene conversion and selectivity of products were evaluated to find a way for the regulation of oxidation products of styrene.
Abstract: By using common cobalt(II) complex as catalyst and oxygen as oxidant, styrene could be oxidized to styrene oxide and benzaldehyde under mild conditions. The impacts of reaction parameters including catalyst amount, initial volume ratio of solvent and temperature on styrene conversion and selectivity of products were evaluated to find a way for the regulation of oxidation products of styrene. The relationship of product yield and some main parameters could be established, which help to provide the target product as more as possible. Kinetic and thermodynamic calculation were also studied for a better understanding of reaction process. Beside the reaction system, the choice of reactors is another important aspect for the regulation of the product. Airlift loop reactor and bubble column reactor were compared for the styrene oxidation reaction.
TL;DR: In this paper, a series of manganese (Mn) containing 3D cubic mesoporous KIT-6 materials with different Si/Mn ratio (100, 50 25 and 10) having Ia3d space group were synthesized for the first time by a facile one-pot hydrothermal process.
TL;DR: It is demonstrated that mesT possessed epoxide hydrolase activity and styrene oxide might be its physiological substrate, and its expression under hypoxic condition suggested its role in intracellular survival of bacteria.
Abstract: Aim: mesT of Mycobacterium tuberculosis, a hypothetical/putative epoxide hydrolase, is predicted to convert toxic epoxides to the more water-soluble and less toxic diols. Detailed characterization of the protein was carried out. Results: mesT demonstrated esterase as well as epoxide hydrolase activity. It was membrane bound and was upregulated under hypoxic conditions. The enzyme was able to degrade styrene oxide. The presence of antisense against this gene resulted in the inhibition of in vitro bacterial growth/survival in the presence of styrene oxide. Conclusion & future perspective: We demonstrated that mesT possessed epoxide hydrolase activity and styrene oxide might be its physiological substrate. Inhibition of mesT reduced the growth of the bacteria in presence of styrene oxide and its expression under hypoxic condition suggested its role in intracellular survival of bacteria.
TL;DR: In this paper, a promising new strategy for immobilizing a water-soluble oligomeric ionic liquid by coating it with mesoporous silica was established, which exhibited a good catalytic activity for the production of cyclic carbonates through the cycloaddition of different epoxides with CO2 under solvent-free conditions.
Abstract: A promising new strategy for immobilizing a water-soluble oligomeric ionic liquid by coating the ionic liquid with mesoporous silica was established. The immobilized ionic liquid (IL@SiO2) exhibited a good catalytic activity for the production of cyclic carbonates through the cycloaddition of different epoxides with CO2 under solvent-free conditions. The IL@SiO2 catalyst was characterized by different techniques such as FTIR spectroscopy, XRD, TG analysis, FESEM-EDX spectroscopy, map analysis, BET analysis, and TEM. Use of 30 mg of the IL@SiO2 catalyst, which contained 0.023 mmol of the oligomeric ionic liquid IL-3, resulted in a yield of cyclic carbonate with styrene oxide of greater than 95% and a selectivity to the cyclocarbonate of almost 100%. We realized that the hydroxyl groups on the surface of silica could play an important role in the reaction through the hydrogen-bonding interactions between the epoxides and the hydroxyl groups. Moreover, the prepared catalyst was very stable under the reaction...
TL;DR: In this article, two diketone complexes of Cu(II and Co(II) were easily synthesized in reaction of M(CH3COO)2 with 2-Hydroxybenzophenone (bpoH).