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Showing papers on "Cyclohexene published in 2023"


Journal ArticleDOI
TL;DR: In this article , 5% Cu-WO3 (CW5) nanosheets were synthesized using a solvothermal route for catalytic epoxidation of olefins to epoxides and hydrogen production.

4 citations


Journal ArticleDOI
TL;DR: In this paper , neutral and cationic indium complexes supported by a Schiff base ligand bearing a binaphthol linker were investigated for alternating copolymerization of CO2 and cyclohexene oxide.
Abstract: Dinuclear indium complexes have been synthesized and characterized. These include neutral and cationic indium complexes supported by a Schiff base ligand bearing a binaphthol linker. The new compounds were investigated for alternating copolymerization of CO2 and cyclohexene oxide. In particular, the neutral indium chloride complex (±)-[(ONapNiN)InCl2]2 (4) showed high conversion of cyclohexene oxide and selectivity for poly(cyclohexene carbonate) formation without cocatalysts at 80 °C under various CO2 pressures (2-30 bar). Importantly, the reactivity of the dinuclear indium chloride complex 4 is drastically different from that of the mononuclear indium chloride complex (±)-(NNiOtBu)InCl2 (5), suggesting a cooperative initiation mechanism involving the two indium centers in 4.

2 citations


Journal ArticleDOI
TL;DR: Salen, Salan, and Salalen chromium (III) chloride complexes have been investigated as catalysts for the ring-opening copolymerization reactions of cyclohexene oxide (CHO) with CO2 and of phthalic anhydride (PA) with limonene oxide(LO) as discussed by the authors .
Abstract: Salen, Salan, and Salalen chromium (III) chloride complexes have been investigated as catalysts for the ring-opening copolymerization reactions of cyclohexene oxide (CHO) with CO2 and of phthalic anhydride (PA) with limonene oxide (LO) or cyclohexene oxide (CHO). In the production of polycarbonates, the more flexible skeleton of salalen and salan ancillary ligands favors high activity. Differently, in the copolymerization of phthalic anhydride with the epoxides, the salen complex showed the best performance. Diblock polycarbonate-polyester copolymers were selectively obtained by one-pot procedures from mixtures of CO2, cyclohexene oxide, and phthalic anhydride with all complexes. In addition, all chromium complexes were revealed to be very active in the chemical depolymerization of polycyclohexene carbonate producing cyclohexene oxide with high selectivity, thus offering the opportunity to close the loop on the life of these materials.

2 citations


Journal ArticleDOI
TL;DR: In this article , the authors describe the chemical synthesis of a new oxovanadium (IV) complex of an N,N-bis(1-naphthalidimine)-o phenylenediamine (VOL).

2 citations


Journal ArticleDOI
Bi Guang, Yiwei Zhang, Yahui Xiao, Mi-mi Su, Yong Liu 
TL;DR: To bridge transition metal complexes and heterogeneous catalysts for allylic oxidation of cyclohexene to 2-cycloenene-1-one with O2 under mild conditions, Cu (Ⅱ) coordinated N-bearing heteropolyacid-based poly(ionic liquid)s (Cu-PDVD-PW) were described in this paper .
Abstract: To bridge transition metal complexes and heterogeneous catalysts for allylic oxidation of cyclohexene to 2-cyclohexene-1-one with O2 under mild conditions, Cu (Ⅱ) coordinated N-bearing heteropolyacid-based poly(ionic liquid)s (Cu-PDVD-PW) were herein...

1 citations


Journal ArticleDOI
TL;DR: A side-reactor column (SRC) configuration, comprising a vacuum column coupled with atmospheric side reactors, is proposed to overcome the thermodynamic restriction in the esterification of cyclohexene with acetic acid, to produce cycloenyl acetate as discussed by the authors .
Abstract: A side-reactor column (SRC) configuration, comprising a vacuum column coupled with atmospheric side reactors, is proposed to overcome the thermodynamic restriction in the esterification of cyclohexene with acetic acid to produce cyclohexyl acetate. Meantime, this configuration can avoid the utilization of the high-pressure steam and provide enough zone for catalyst loading. In order to obtain the minimum total annual cost (TAC), the process is optimized by a mixed-integer nonlinear programming optimization method based on the improved bat algorithm. The results indicate that the optimized SRC configuration saves about 44.81% of the TAC compared to the reactive distillation process. Based on the optimized SRC process, dynamic control is carried out. The dual-point temperature and temperature-composition control structures are proposed to reject throughput and feed composition disturbances. The dynamic performances demonstrate that the temperature-composition control structure is better in maintaining product purity.

1 citations


Journal ArticleDOI
TL;DR: Fe(II) complexes with pentadentate ligands, including N-heterocyclic carbene moieties, were prepared and electrostatically attached onto the perfluorinated surface of a mesoporous aluminosilicate as mentioned in this paper .

1 citations


Journal ArticleDOI
TL;DR: In this article , a thermally pre-activated LiAlH4/Fe0 catalyst was shown to be a remarkably potent cooperative catalyst for hydrogenation of multi-substituted alkenes and benzene or toluene.
Abstract: Alkenes that normally do not react with LiAlH4 (3-hexene, cyclohexene, 1-Me-cyclohexene), can be reduced to the corresponding alkanes by a mixture of LiAlH4 and Fe0 (the iron was activated by Metal-Vapour-Synthesis). This alkene-to-alkane conversion with a stoichiometric quantity of LiAlH4/Fe0 does not need quenching with water or acids, implying that both H's originate from LiAlH4. The LiAlH4/Fe0 combination is also a remarkably potent cooperative catalyst for hydrogenation of multi-substituted alkenes and benzene or toluene. An induction period of circa two hours and the minimally required temperature of 120 °C, suggests that the actual catalyst is a combination of Fe0 and the decomposition product of LiAlH4 (LiH and Al0). A thermally pre-activated LiAlH4/Fe0 catalyst did not need an induction time and is also active at room temperature and 1 bar H2. A combination of AliBu3 and Fe0 is an even more active hydrogenation catalyst. Without pre-activation, tetra-substituted alkenes like Me2C=CMe2 and toluene could be fully hydrogenated.

1 citations


Journal ArticleDOI
TL;DR: In this article , a benzothiazole-linked Fe-metalated porous organic polymers (Fc-Bz-POP) was constructed using FDC, 1,3,5-tris(4-aminophenyl) benzene (APB), and elemental sulfur (S8) via a template-free one-pot synthetic approach.
Abstract: In recent times, a self-complementary balanced characteristic feature with the combination of both covalent bonds (structural stability) and open metal sites (single-site catalysis) introduced an advanced emerging functional nanoarchitecture termed metalated porous organic polymers (M-POPs). However, the development of M-POPs in view of the current interest in catalysis has been realized still in its infancy and remains a challenge for the years to come. In this work, we built benzothiazole-linked Fe-metalated porous organic polymer (Fc-Bz-POP) using ferrocene dicarboxaldehyde (FDC), 1,3,5-tris(4-aminophenyl) benzene (APB), and elemental sulfur (S8) via a template-free, multicomponent, cost-effective one-pot synthetic approach. This Fc-Bz-POP is endowed with unique features including an extended network unit, isolated active sites, and catalytic pocket with a possible local structure, in which convergent binding sites are positioned in such a way that substrate molecules can be held in close proximity. Prospective catalytic application of this Fc-Bz-POP has been explored in executing catalytic allylic "C-H" bond functionalization of cyclohexene (CHX) in water at room temperature. Catalytic screening results identified that a superior performance with a CHX conversion of 95% and a 2-cyclohexene-1-ol selectivity (COL) of 80.8% at 4 h and 25 °C temperature has been achieved over Fc-Bz-POP, thereby addressing previous shortcomings of the other conventional catalytic systems. Comprehensive characterization understanding with the aid of synchrotron-based extended X-ray absorption fine structure (EXAFS) analysis manifested that the Fe atom with an oxidation state of +2 in our Fc-Bz-POP catalytic system encompasses a sandwich structural environment with the two symmetrical eclipsed cyclopentadienyl (Cp) rings, featuring nearest-neighbor (NN) Fe-C (≈2.05 Å) intramolecular bonds, as validated by the Fe L3-edge EXAFS fitting result. Furthermore, in situ attenuated total reflection-infrared spectroscopy (ATR-IR) analysis data for liquid-phase oxidation of cyclohexene allow for the formulation of a molecular-level reaction mechanistic pathway with the involvement of specific reaction intermediates, which is initiated by the radical functionalization of the allyl hydrogen. A deep insight investigation from density functional theory (DFT) calculations unambiguously revealed that the dominant pathway from cyclohexene to 2-cyclohexene-1-ol is initiated by an allyl-H functionalization step accompanied by the formation of 2-cyclohexene-1-hydroperoxide species as the key reaction intermediate. Electronic properties obtained from DFT simulations via the charge density difference plot, Bader charge, and density of state (DOS) demonstrate the importance of the organic polymer frame structure in altering the electronic properties of the Fe site in Fc-Bz-POP, resulting in its high activity. Our contribution has great implications for the precise design of metalated porous organic polymer-based robust catalysts, which will open a new avenue to get a clear image of surface catalysis.

1 citations


Journal ArticleDOI
TL;DR: In this article , the reactivity of organic molecules with different internal ring strain on a stainless steel surface in inert (N2), oxidizing (O2), and reducing (H2) environments at room temperature was investigated.
Abstract: Tribochemistry, which is another name for mechanochemistry driven by shear, deals with complex and dynamic interfacial processes that can lead to surface wear or formation of beneficial tribofilms. For better mechanistic understanding of these processes, we investigated the reactivity of tribopolymerization of organic molecules with different internal ring strain (methylcyclopentane, cyclohexane, and cyclohexene) on a stainless steel (SS) surface in inert (N2), oxidizing (O2), and reducing (H2) environments at room temperature. On the clean stainless steel surface, precursor molecules were found to physisorb with a broad range of molecular orientations. In inert and reducing environments, the strain-free cyclohexane showed the lowest tribochemical activity among the three molecules tested. Compared to the N2 environment, the tribochemical activity in H2 was suppressed. In the O2 environment, only cyclohexene produced tribofilms and methylcyclopentane while cyclohexane did not. When tribofilms were analyzed with Raman spectroscopy, the spectral features of diamond-like carbon (DLC) or amorphous carbon (a-C) were observed due to photochemical degradation of triboproducts. Based on infrared spectroscopy, tribofilms were found to be organic polymers containing oxygenated groups. Whenever polymeric tribrofilms were produced, wear volume was suppressed by orders of magnitudes but not completely to zero. These results support previously suggested mechanisms which involve surface oxygen as a reactant species in the tribopolymerization process.

1 citations


Journal ArticleDOI
TL;DR: In this article , a new phosphorous-free rhodium supported on a nitrogen-doped silica was successfully used as a catalyst for the hydroformylation of alkenes.
Abstract: A new phosphorous-free rhodium supported on a nitrogen-doped silica was successfully used as a catalyst for the hydroformylation of alkenes. The obtained material and the catalyst were characterized by XRD, XPS, FTIR, SEM, TEM, ICP AES, and low-temperature nitrogen adsorption–desorption measurements. The catalytic performance was studied by the example of the hydroformylation of octene-1 at temperatures of 80–140 °C and a pressure of 5.0 MPa. The catalyst provided a 99% conversion of 1-octene with a 98% yield of aldehydes and showed a good conversion of styrene and cyclohexene. The catalyst can be repeatedly used in ten consecutive cycles, with its activity remaining constant.

Journal ArticleDOI
TL;DR: In this paper , it was shown that when the catalyst, dioxgen, and substrate are present simultaneously in the reaction mixture, the iron(IV) oxo adduct [(N4Py)FeIV=O]2+ is formed, which is the oxidative species.
Abstract: The use of dioxygen as an oxidant in fine chemicals production is an emerging problem in chemistry for environmental and economical reasons. In acetonitrile, the [(N4Py)FeII]2+ complex, [N4Py—N,N-bis(2-pyridylmethyl)-N-(bis-2-pyridylmethyl)amine] in the presence of the substrate activates dioxygen for the oxygenation of cyclohexene and limonene. Cyclohexane is oxidized mainly to 2-cyclohexen-1-one, and 2-cyclohexen-1-ol, cyclohexene oxide is formed in much smaller amounts. Limonene gives as the main products limonene oxide, carvone, and carveol. Perillaldehyde and perillyl alcohol are also present in the products but to a lesser extent. The investigated system is twice as efficient as the [(bpy)2FeII]2+/O2/cyclohexene system and comparable to the [(bpy)2MnII]2+/O2/limonene system. Using cyclic voltammetry, it has been shown that, when the catalyst, dioxgen, and substrate are present simultaneously in the reaction mixture, the iron(IV) oxo adduct [(N4Py)FeIV=O]2+ is formed, which is the oxidative species. This observation is supported by DFT calculations.

Journal ArticleDOI
TL;DR: In this paper , a series of MnMoP catalysts were prepared by ionic liquid assisted thermal synthesis method and characterized by powder X-ray diffraction, Fourier Transform Infrared Spectrometer, Scanning Electron Microscope, Xray Photoelectron Spectroscope and NH3-Temperature Programmed Desorption.


Journal ArticleDOI
TL;DR: In this paper , rates of ruthenium-catalyzed alternating ring opening metathesis (AROM) of cyclohexene with two different Ru-cyclohexylidene carbenes derived from bicyclo[4.2.0] oct-6-ene-7-carboxamide were investigated.
Abstract: We report an investigation of rates of ruthenium-catalyzed alternating ring opening metathesis (AROM) of cyclohexene with two different Ru-cyclohexylidene carbenes derived from bicyclo[4.2.0]oct-6-ene-7-carboxamides (A monomer) that bear different side chains. These monomers are propylbicyclo[4.2.0]oct-6-ene-7-carboxamide and N-(2-(2-ethoxyethoxy)ethanylbicyclo[4.2.0]oct-6-ene-7-carboxamide. The amide substitution of these monomers directly affects both the rate of the bicyclo[4.2.0]oct-6-ene-7-carboxamide ring opening and the rate of reaction of the resulting carbene with cyclohexene (B monomer). The resulting Ru-cyclohexylidenes underwent reversible ring opening metathesis with cyclohexene. However, the thermodynamic equilibrium disfavored cyclohexene ring opening. Utilization of triphenylphosphine forms a more stable PPh3 ligated complex, which suppresses the reverse ring closing reaction and allowed direct measurements of the forward rate constants for formation of various A-B and A-B-A′ complexes through carbene-catalyzed ring-opening metathesis and thus gradient polymer structure-determining steps. The relative rate of the propylbicyclo[4.2.0]oct-6-ene-7-carboxamide ring opening is 3-fold faster than that of the N-(2-(2-ethoxyethoxy)ethanylbicyclo[4.2.0]oct-6-ene-7-carboxamide. In addition, the rate of cyclohexene ring-opening catalyzed by the propyl bicyclooctene is 1.4 times faster than when catalyzed by the ethoxyethoxy bicyclooctene. Also, the subsequent rates of bicyclo[4.2.0]oct-6-ene-7-carboxamide ring opening by propyl-based Ru-hexylidene are 1.6-fold faster than ethoxyethoxy-based Ru-hexylidene. Incorporation of the rate constants into reactivity ratios of bicyclo[4.2.0]amide-cyclohexene provides prediction of copolymerization kinetics and gradient copolymer structures.

Journal ArticleDOI
TL;DR: In this paper , the possibility of combining acid-catalytic cyclohexanol dehydration and alkoxy carbonylation in a single reaction in order to achieve high yields of the target cycloenecarboxylate product under mild conditions using the Pd(OAc)2-PPh3-p-toluenesulfonic acid catalytic system was studied.
Abstract: Objectives. To study the possibility of combining acid-catalytic cyclohexanol dehydration and alkoxycarbonylation of the formed cyclohexene with cyclohexanol and carbon(II) oxide in a single reactor in order to achieve high yields of the target cyclohexyl cyclohexanecarboxylate product under mild conditions using the Pd(OAc)2–PPh3–p-toluenesulfonic acid catalytic system.Methods. The combined process took place in a toluene medium in a periodic steel reactor designed to operate at elevated pressure, equipped with a glass insert, a magnetic stirrer, and a sampler, as well as gas input and discharge devices. The reaction mass with the components of the catalytic system was placed in a glass reactor inside a steel autoclave. The reaction mass samples obtained during the combined process were analyzed by gas–liquid chromatography with a flame ionization detector.Results. The possibility of combining cyclohexanol dehydration catalyzed by p-toluenesulfonic acid monohydrate and formed cyclohexene alkoxycarbonylation with cyclohexanol and CO during catalysis by the Pd(OAc)2–PPh3–p-toluenesulfonic acid system in a single reactor was demonstrated. Under mild conditions (temperature 110°C; CO pressure 2.1 MPa), the target product yield reached 64.8% in 5 h. However, the combined process is complicated by the formation of a cyclohexanecarboxylic acid by-product formed as a result of the cyclohexyl cyclohexanecarboxylate hydrolysis and the cyclohexene hydroxycarbonylation.Conclusions. The reactions of intramolecular acid-catalytic cyclohexanol dehydration and formed cyclohexene alkoxycarbonylation catalyzed by the Pd(OAc)2–PPh3–p-toluenesulfonic acid system can be combined in a single reactor. p-Toluenesulfonic acid can simultaneously act as a catalyst for the cyclohexanol dehydration and a co-catalyst of the palladium–phosphine system of cyclohexene alkoxycarbonylation. The involvement of cyclohexene, representing a product of reversible cyclohexanol dehydration, in the alkoxycarbonylation reaction is a factor in shifting the dehydration reaction equilibrium towards the formation of cyclohexene. Cyclohexanecarboxylic acid is a by-product of the proposed combined process. A factor in the reduction of target product yield is water formed as a result of cyclohexanol dehydration due to the involvement of the latter in the hydrolysis reaction and the course of the cyclohexene hydroxycarbonylation.


Journal ArticleDOI
TL;DR: In this article , the authors reported a facile and scalable approach for the synthesis of Fe-based MOF MIL-88A(Fe) via a simple liquid-phase route at atmosphere pressure, and its application as a heterogeneous catalyst for the efficient aerobic oxidation of cyclohexene to value-added 2-cycloenene-1-ol.
Abstract: Herein, we reported a facile and scalable approach for the synthesis of Fe-based MOF MIL-88A(Fe) via a simple liquid-phase route at atmosphere pressure, and its application as a heterogeneous catalyst for the efficient aerobic oxidation of cyclohexene to value-added 2-cyclohexene-1-ol. Over 130 g of spindle-shaped MIL-88A(Fe) nanocrystals with high crystallinity, monodispersed particle size, and large specific surface area were easily synthesized per batch according to our method. The resultant MIL-88A(Fe) exhibited a high catalytic activity (conversion: 81%) with 70% selectivity for 2-cyclohexene-1-ol in the aerobic oxidation of cyclohexene with O2 as the sole oxidant under mild reaction conditions (0.5 MPa of O2, 353 K for 8 h), outperforming the analogues reported in the literatures. The combined experimental and theoretical approach support the reaction mechanism of the oxidation of cyclohexene via both the free radical reaction pathway and Fe-mediated reaction pathway, resulting in the selective formation of 2-cyclohexene-1-ol.

Journal ArticleDOI
TL;DR: The thermal decomposition of isopropylcyclohexane (IPCH) has been investigated at the CBS-QB3 and CASSCF/MRCI levels of theory as mentioned in this paper .

Journal ArticleDOI
TL;DR: In this article , a cycloaddition-fragmentation sequence from benzene oxide and a nitroso-or azo-dienophile was investigated as a tool for access to highly substituted cyclohexene oxide derivatives.
Abstract: A cycloaddition-fragmentation sequence from benzene oxide and a nitroso- or azo-dienophile was investigated as a tool for access to highly substituted cyclohexene oxide derivatives. Alkyl lithium-promoted fragmentation of the cycloadducts led to the cyclic derivatives after 1,4- or 1,2-addition of a second equivalent of the lithium reagent. New fragmentation processes were observed when using non-nucleophilic bases of highly hindered alkyl lithium reagents. All reactions proceeded with complete stereocontrol.

Journal ArticleDOI
TL;DR: In this article , vanadium oxide-modified hydroxyapatite (HAP) with varying vanadium content was synthesized by coprecipitation and impregnation methods.
Abstract: Vanadium oxide-modified hydroxyapatite (HAP) with varying vanadium content was synthesized by the coprecipitation and impregnation methods. The structures of the two series of catalysts were compared, and the effects of vanadium content on catalytic properties in cyclohexane oxidative dehydrogenation (ODH) are evaluated. The XRD, UV‒Vis and XPS analyses indicate that the V species in the two series of samples exist in different chemical environments. The samples prepared by the impregnation method are mainly composed of V2O5 species, while the samples prepared by the coprecipitation method show a replacement of a part of the P in the HAP lattice by VO4. The influence of the preparation method and vanadium content on the reaction rate and reaction route for the ODH of cyclohexane is investigated. VHAP shows higher cyclohexene selectivity. The effect of VOx species on the ODH reaction of cyclohexane was investigated and the reaction mechanism was proposed.

Journal ArticleDOI
TL;DR: In this paper , the commercial ionic liquids (IL), namely tris (2-hydroxyethyl) methylammonium methylsulfate and tributyl methyl phosphonium methyl sulphate were used for the separation of three systems namely benzene-hexane, toluene-heptane and thiophene-cyclohexene at ambient conditions.

Journal ArticleDOI
TL;DR: In this paper , a thermally pre-activated LiAlH4/Fe0 catalyst was shown to be a remarkably potent cooperative catalyst for hydrogenation of multi-substituted alkenes and benzene or toluene.
Abstract: Alkenes that normally do not react with LiAlH4 (3-hexene, cyclohexene, 1-Me-cyclohexene), can be reduced to the corresponding alkanes by a mixture of LiAlH4 and Fe0 (the iron was activated by Metal-Vapour-Synthesis). This alkene-to-alkane conversion with a stoichiometric quantity of LiAlH4/Fe0 does not need quenching with water or acids, implying that both H's originate from LiAlH4. The LiAlH4/Fe0 combination is also a remarkably potent cooperative catalyst for hydrogenation of multi-substituted alkenes and benzene or toluene. An induction period of circa two hours and the minimally required temperature of 120 °C, suggests that the actual catalyst is a combination of Fe0 and the decomposition product of LiAlH4 (LiH and Al0). A thermally pre-activated LiAlH4/Fe0 catalyst did not need an induction time and is also active at room temperature and 1 bar H2. A combination of AliBu3 and Fe0 is an even more active hydrogenation catalyst. Without pre-activation, tetra-substituted alkenes like Me2C=CMe2 and toluene could be fully hydrogenated.

Journal ArticleDOI
TL;DR: In this article , a new method is proposed for the preparation of 4,4-dimethyl-2-cyclohexene-1-one in high yield by selective catalytic pyrolysis of cellulose with FeCl3-doped [Bmim]OTf magnetic ionic liquids.
Abstract: 4,4-dimethyl-2-cyclohexene-1-one is a valuable ketone compound, which is an important (±)-cuparene and filicinic acid intermediate, but the synthetic method of 4,4-dimethyl-2-cyclohexene-1-one is rarely mentioned in the marketplace. This article, a new method is proposed for the preparation of 4,4-dimethyl-2-cyclohexen-1-one in high yield by selective catalytic pyrolysis of cellulose with FeCl3-doped [Bmim]OTf magnetic ionic liquids. By studying the effect of temperature on the yield of pyrolysis products in [Bmim]OTf, the results showed that the optimal pyrolysis temperature of cellulose in [Bmim]OTf was 330°C and the maximum relative content of 4,4-dimethyl-2-cyclohexen-1-one was 86.81%. In addition, different FeCl3/[Bmim]OTf mass ratios were found at 330°C. The relative yield of the target product reached a maximum (91.31%) when iron ions with excellent catalytic activity were introduced, at which the FeCl3/[Bmim]OTf mass ratio was 10%. At last, based on the basic model of cellulose monomer, the evolution pathway of ketones products was proposed, which provides ideas for the production of sustainable chemical products from cellulose.

Journal ArticleDOI
TL;DR: In this paper , the BEA-Ti and porphyrin H2MTPP catalysts were combined with (metallo)porphyrin, TiIV sites and tert-butyl hydroperoxide (TBHP) catalysts to obtain cyclohexene oxide and 2-cyclohexen-1-one.
Abstract: Selective epoxidation and allylic oxidation of cyclohexene were realized in the presence of BEA-Ti and (metallo)porphyrin catalysts. The integration of BEA-Ti and porphyrin H2MTPP afforded cyclohexene oxide with excellent selectivity (cyclohexene oxide/ 2-cyclohexen-1-one=85:15). BEA-Ti and metalloporphyrin MnMTPP yielded 2-cyclohexen-1-one with high selectivity (cyclohexene oxide/ 2-cyclohexen-1-one=12:88). Resulting active species involving of (metallo)porphyrin, TiIV sites and tert-butyl hydroperoxide (TBHP) promoted the oxidation process of cyclohexene. A possible mechanism resulting in the formation cyclohexene oxide and 2-cyclohexen-1-one was proposed. The outer-sphere effect constructed by (metallo)porphyrin, TiIV sites and TBHP on the surface of BEA-Ti framework improved the epoxidation and allylic oxidation both in the conversion and selectivity.

Journal ArticleDOI
TL;DR: In this paper , a supported ionic liquid (IL) functionalized organic ligand that is able to accept metal sites was used as a single component solid catalyst for the copolymerization of CO2 and cyclohexene oxide.
Abstract: The capture and conversion of anthropogenic CO2 is a paramount challenge for our global ecosystem. An optimal way of to cope with the emitted CO2 is to efficiently convert it to value‐added materials. Whereas nature sequesters CO2 by making sugar‐based polymers, utilizing CO2 to make highly demanded synthetic polymers such as polycarbonates is of great value. The present work reports the synthesis of a new supported ionic liquid (IL) functionalized organic ligand that is able to accept metal sites. After incorporating di‐nuclear magnesium, it was utilized as a single‐component solid catalyst for the copolymerization of CO2 and cyclohexene oxide. The obtained solid catalyst was found to be active under mild CO2 pressures of (1–15 atm) giving a turnover number of up to 283 and turnover frequency up to 11.8 h−1. To the authors knowledge, these rates are the highest obtained using a heterogeneous catalyst, maintaining 96–99 % polycarbonates selectivity and 97–99 % carbonate repeat units. In addition, the obtained polymers showed high molecular weights (16.7 to 11.7 kg/mol) with 1.05 to 1.6 dispersity (Đ). The catalyst was recycled 4 times, under regular laboratory conditions and without any intermediate reactivation steps, which provided ∼3 g of polycarbonate for ∼0.03 g catalyst (100 : 1) at 80 °C in neat cyclohexene oxide and 15 atm CO2.

Journal ArticleDOI
TL;DR: In this article , a series of dihydroxybenzene-derived ILs was synthesised via a halide-free, eco-friendly methodology and fully characterized, observing that methyltrioctylammonium hydroquinolate was the most active catalyst in the proposed optimized conditions.
Abstract: A series of dihydroxybenzene‐derived ILs was synthesised via a halide‐free, eco‐friendly methodology and fully characterized. Their activity as single component catalyst towards synthesis of cyclic organic carbonates (COCs) via CO2 insertion into terminal epoxides was evaluated, observing that methyltrioctylammonium hydroquinolate, [N1888][HYD], was the most active catalyst in the proposed optimized conditions ([N1888][HYD] 10 % mol, T=120 °C, t=6 h, p0(CO2)=2.0 MPa, 12 examples, conversion >99 %, yield up to 98 %). Interestingly, [N1888][HYD] was also an active catalyst for CO2 insertion reactions with cyclohexene oxide (CHO), observing formation of both the COC and polycarbonate product. It is proposed that for p0(CO2)≥1.0 MPa, the catalytically active species is the hemicarbonate derivative of the hydroquinolate anion, active towards epoxide ring opening via an unusual hemicarbonate‐alkoxide pathway.

Journal ArticleDOI
01 Jul 2023-Fuel
TL;DR: In this article , surface-silylated titania-silica catalysts can be prepared by a silylation method using hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS) as the silane reagents.

Journal ArticleDOI
TL;DR: In this article , a series of Cu(II and Mn(II) complexes with Schiff base ligands derived from 2-furylmethylketone (Met), 2furaldehyde (Fur), and 2-hydroxyacetopheneone (Hyd) have been synthesized in situ on SBA-15-NH2, MCM-48-NH 2, and MCM41-N2 functionalized supports.
Abstract: New series of Cu(II) and Mn(II) complexes with Schiff base ligands derived from 2-furylmethylketone (Met), 2-furaldehyde (Fur), and 2-hydroxyacetopheneone (Hyd) have been synthesized in situ on SBA-15-NH2, MCM-48-NH2, and MCM-41-NH2 functionalized supports. The hybrid materials were characterized by X-ray diffraction, nitrogen adsorption–desorption, SEM and TEM microscopy, TG analysis, and AAS, FTIR, EPR, and XPS spectroscopies. Catalytic performances were tested in oxidation with the hydrogen peroxide of cyclohexene and of different aromatic and aliphatic alcohols (benzyl alcohol, 2-methylpropan-1-ol, and 1-buten-3-ol). The catalytic activity was correlated with the type of mesoporous silica support, ligand, and metal–ligand interactions. The best catalytic activity of all tested hybrid materials was obtained in the oxidation of cyclohexene on SBA-15-NH2-MetMn as a heterogeneous catalyst. No leaching was evidenced for Cu and Mn complexes, and the Cu catalysts were more stable due to a more covalent interaction of the metallic ions with the immobilized ligands.

Journal ArticleDOI
01 Jan 2023-Fuel
TL;DR: In this paper , the potential energy surfaces and rate constants of cyclohexene plus H, OH, HO 2 radicals were investigated with high-level quantum chemistry methods, and the molecular geometries and vibrational frequencies were calculated for all stationary points at BHLYP/6-311++G(d,p) level.