Cyclohexene Oxide Research Articles

Ionic liquids assisted synthesis of graphite carbon nitride for one-pot aerobic oxidation of cyclohexane to adipic acid

Adipic acid (AA) is a crucial intermediate in the production of nylon monomers, which is generally obtained by the oxidation of cyclohexane. However, difficult C-H activation and easy overoxidation make it extremely challenging to obtain highly selective AA. Herein, ionic liquid (IL) assisted synthesis of graphitic carbon nitride (g-C3N4) was designed for one-pot oxidation of cyclohexane to AA. The incorporation of C and S elements and the formation of N vacancies were brought with the presence of IL. 26.1% conversion and 51.2% AA selectivity were achieved over [Bmim][HSO4] (1-Butyl-3-methylimidazolium hydrogen sulfate) modified g-C3N4, which significantly increased AA selectivity by 18% compared to unmodified g-C3N4. The changes in electronic structure of g-C3N4 were assumed resposible for the improvement of AA selectivity by increasing the adsorption of cyclohexanone. Besides, the reduction of alkaline sites caused by the introduction of S atoms and N vacancies was benefit to remove AA avoiding excessive oxidation.

Fe(III)-Based Phenylsilsesquioxane/Acetylacetonate Complexes: Synthesis, Cage-like Structure, and High Catalytic Activity.

Unprecedented iron-based silsesquioxane/acetylacetonate complexes were synthesized. The intriguing cage-like structure of compounds is alkaline metal-dependent: the Fe2Li2 complex includes condensed Si6-silsesquioxane and four acetylacetonate ligands; the Fe4Na4 complex exhibits two cyclic Si4-silsesquioxane and eight acetylacetonate ligands, while the Fe3K3 complex features two cyclic Si3-silsesquioxane and six acetylacetonate ligands. The latter case is the very first observation of small trimeric silsesquioxane ligands in the composition of cage-like metallasilsesquioxanes. The Fe4Na4-based complex exhibits a record high activity in the oxidation of inert alkanes with peroxides (55% yield of oxygenates in cyclohexane oxidation). It also acts as a catalyst in the cycloaddition of CO2 with epoxides, leading to cyclic carbonates in good yields (58-96%).

Cyclohexene oxide CA, a derivative of zeylenone, exhibits anti-cancer activity in glioblastoma by inducing G0/G1 phase arrest through interference with EZH2.

Introduction: Due to its highly aggressiveness and malignancy, glioblastoma (GBM) urgently requires a safe and effective treatment strategy. Zeylenone, a natural polyoxygenated cyclohexenes compound isolated from Uvaria grandiflora, has exhibited potential biological activities in various human diseases, including tumors. Methods: We designed and synthesized a series of (+)-Zeylenone analogues and evaluated their anti-GBM roles through structural-activity analysis. Cell Counting Kit-8, TUNEL, transwell and flow cytometry were employed for investigating the anticancer effects of CA on GBM cells. Western blotting, molecular docking, qRT-PCR and ChIP assays were performed to reveal the underlying mechanisms by which CA regulates the GBM cell cycle. The nude mouse xenograft model, HE staining, immunohistochemistry and was used to evaluate the anticancer effect of CA in vivo. Results: We identified CA ((1R, 2R, 3S)-3-p-fluorobenzoyl-zeylenone) as having the lowest IC50 value in GBM cells. CA treatment significantly inhibited the malignant behaviors of GBM cells and induced G0/G1 phase arrest in vitro. Furthermore, we validated the molecular mechanism by which CA interferes with EZH2, attenuating the down-regulation of cyclin-dependent kinase inhibitors p27 and p16 by the PRC2 complex. By establishing orthotopic nude mice models, we further validated the inhibitory role of CA on tumorigenesis of GBM cells in vivo and its potential values to synergistically potentiate the anti-tumor effects of EZH2 inhibitors. Conclusion: Overall, this paper elucidated the anti-GBM effects and potential mechanisms of CA, and may provide a therapeutic drug candidate for GBM treatment.

Construction of multifunctional lanthanum manganese mixed nanoparticles mediated by ionic liquids for selective aerobic oxidation of cyclohexane

Construction of multifunctional lanthanum manganese mixed nanoparticles mediated by ionic liquids for selective aerobic oxidation of cyclohexane

Tetracosanuclear nickel complexes as effective catalysts for cycloaddition of carbon dioxide with epoxides.

A series of well-defined tetracosanuclear nickel complexes 3-7 facilely produced by one-pot synthesis were active catalysts for cycloaddition of CO2 and cyclohexene oxide (CHO). These nickel complexes were doughnut-like supramolecular coordination complexes involving eight repeating units, and each of them contains one Schiff base ligand and three nickel(II) ions. Notably, the 24-nuclear nickel cluster complex 3 in combination with nucleophilic additives was the most efficient catalyst to mediate CO2 coupling with CHO to generate CO2-based cis-cyclohexene carbonates. In addition to CO2/CHO cycloaddition, complex 3 was also found to effectively couple CO2 with other alicyclic epoxides, generating the corresponding cyclic carbonates. Additionally, kinetic investigations for CO2 cycloaddition of CHO using 3 were reported.

Catalytic copolymerization of carbon dioxide and cyclohexene oxide by a trinuclear cyclohexane-bridged tetradentate Schiff base chromium complex

The development of catalytic systems is a central area of research in carbon dioxide (CO2) and epoxy copolymerization.

Bimetallic nickel complexes containing imidazole-based phenolate ligands as efficient catalysts for the copolymerization of carbon dioxide with epoxides.

The utilization of hexadentate imidazole-derived diamine-bisphenolate ligands to construct structurally well-defined bimetallic nickel catalysts that enable the mediation of the copolymerization of carbon dioxide with alicyclic epoxides was reported for the first time. A series of dinickel carboxylate/nitrophenolate complexes were facilely prepared through a one-pot procedure and their structures were fully determined by single crystal X-ray structural analysis. Dinickel complexes 1-10 were used as single-component catalysts, and were evaluated for the copolymerization of CO2 and cyclohexene oxide (CHO), for which acetato-incorporated complex 1 was proved to exhibit the best activity. Not only has the controllability of binickel catalyst 1 for CO2/CHO copolymerization been demonstrated, but also an "immortal" character for the same polymerization has been realized. Furthermore, detailed kinetic studies of polymerization catalysis of this type were undertaken, and the kinetics results revealed a first-order dependence on both Ni complex 1 and CHO concentrations. This is a successful example of the introduction of the easily accessible nitrogen-heterocycle group, the imidazole moiety, into phenolate ligands for the development of high-performance homogeneous catalysts towards the bimetallic complex-catalyzed copolymerization of CO2 and epoxides.

Switchable, chiral aluminium catalysts for ring opening polymerisations.

A switchable, solvent-free catalytic system was developed in which Al methyl aminebis(phenolate) catalysts selectively initiate the formation of a polyether from cyclohexene oxide under CO2 atmosphere or the ring opening copolymerisation (ROCoP) of cyclohexene oxide and CO2 through the addition of a PPNCl (bis(triphenylphosphine)iminium chloride) cocatalyst to form poly(cyclohexene carbonate).

Selective synthesis of cyclic alcohols from cycloalkanes using nickel(ii) complexes of tetradentate amidate ligands.

Selective functionalisation of hydrocarbons using transition metal complexes has evoked significant research interest in industrial chemistry. However, selective oxidation of unactivated aliphatic C-H bonds is challenging because of the high bond dissociation energies. Herein, we report the synthesis, characterisation and catalytic activity of nickel(ii) complexes ([Ni(L1-L3)(OH2)2](ClO4)2 (1-3)) of monoamidate tetradentate ligands [L1: 2-(bis(pyridin-2-ylmethyl)amino)-N-phenylacetamide, L2: 2-(bis(2-pyridin-2-ylmethyl)amino)-N-(naphthalen-1-yl)acetamide, L3: N-benzyl-2-(bis(pyridin-2-ylmethyl)amino)acetamide] in selective oxidation of cycloalkanes using m-CPBA as the oxidant. In cyclohexane oxidation, catalysts showed activity (TON) in the order 1 (654) > 2 (589) > 3 (359) with a high A/(K + L) ratio up to 23.6. Using catalyst 1, the substrate scope of the reaction was broadened by including other cycloalkanes such as cyclopentane, cycloheptane, cyclooctane, adamantane and methylcyclohexane. Further, the Fenton-type reaction in the catalytic cycle was discarded based on the relatively high 3°/2° ratio of 8.6 in adamantane oxidation. Although the formation of chlorinated products during the reactions confirmed the contribution of the 3-chlorobenzoyloxy radical mechanism, the high alcohol selectivity obtained for the reactions indicated the participation of nickel-based oxidants in the oxidation process.

SiO2 supported Ce–Co mixed oxide catalyzed selective allylic oxidation of cyclohexene

CeO2–Co3O4/SiO2 catalyst exhibited superior catalytic activity compared to pure oxides for cyclohexene oxidation with 94% conversion and 90% of selectivity towards allylic products.

Unravelling the different pathways of cyclohexene oxidation via a peroxyl radical generated from tert-butyl hydroperoxide (TBHP) by various metal salts

Two different mechanisms were obtained in the selective oxidation of cyclohexene catalyzed by CuCl2 and VCl3 respectively in presence of TBHP. The two opposed mechanisms are mainly caused by the roles of the t-BuOO˙ radical in catalytic oxidations.

Selective oxidation of cyclohexane to KA oil over Co and Fe nanoparticles immobilized on layered double hydroxide nanocatalytic system

In this study, we prepared Co and Fe nanoparticles supported on a layered double hydroxide abbreviated as CoNPs@LDH and FeNPs@LDH.

Enabling a bioinspired N,N,N-copper coordination motif through spatial control in UiO-67: synthesis and reactivity.

Metal-organic frameworks (MOFs) featuring zirconium-based clusters are widely used for the development of functionalized materials due to their exceptional stability. In this study, we report the synthesis of a novel N,N,N-ligand compatible with a biphenyl dicarboxylic acid-based MOF. However, the resulting copper(I) complex exhibited unexpected coordination behaviour, lacking the intended trifold coordination motif. Herein, we demonstrate the successful immobilization of a bioinspired ligand within the MOF, which preserved its crystalline and porous nature while generating a well-defined copper site. Comprehensive spectroscopic analyses, including X-ray absorption, UV/Vis, and infrared spectroscopy, were conducted to investigate the copper site and its thermal behaviour. The immobilized ligand exhibited the desired tridentate coordination to copper, providing access to a coordination motif otherwise unattainable. Notably, water molecules were also found to coordinate to copper. Upon heating, the copper centre within the MOF exhibited reversible dehydration, suggesting facile creation of open coordination sites. Furthermore, the copper site displayed reduction at elevated temperatures and subsequent susceptibility to oxidation by molecular oxygen. Lastly, both the molecular complexes and the MOF were evaluated as catalysts for the oxidation of cyclohexane using hydrogen peroxide. This work highlights the successful immobilization of a bioinspired ligand in a zirconium-based MOF, shedding light on the structural features, thermal behaviour, and catalytic potential of the resulting copper sites.

Synthesis and characterization of mesoporous silica supported metallosalphen-azobenzene complexes: efficient photochromic heterogeneous catalysts for the oxidation of cyclohexane to produce KA oil.

The oxidation of cyclohexane to produce KA oil (cyclohexanone and cyclohexanol) is important industrially but faces challenges such as low cyclohexane conversion at high KA oil selectivity, and difficult catalyst recyclability. This work reports the synthesis and evaluation of new heterogeneous catalysts consisting of Co(ii), Mn(ii), Ni(ii) and Cu(ii) salphen-azobenzene complexes [ML1] immobilized on amino-functionalized mesoporous silica (SBA-15, MCM-41, MCM-48) through coordination bonding. In the first step, the salphen-azobenzene ligand was synthesized and complexed with Co, Mn, Ni and Cu metal ions. In the second step, aminopropyltriethoxysilane (APTES) was grafted onto the surface of different types of commercial mesoporous silica. The immobilization of [ML1] onto the mesoporous silica surface and the thermal stability of the obtained materials were confirmed using different characterization techniques such as FT-IR, powder XRD, SEM, TEM, BET, and TGA. The obtained results revealed high dispersion of [ML1] through the silica surface. The catalytic activity of the prepared materials Silica-N-ML1 was evaluated on the cyclohexane oxidation to produce KA oil using various oxidants. The cis-trans isomerization of the azobenzene upon UV irradiation was found to affect the catalytic performance of Silica-N-ML1. The cis isomer of SBA-15-N-CoL1 exhibited the highest cyclohexane conversion (93%) and KA selectivity (92%) under mild conditions (60 °C, 6 h) using m-CPBA as oxidant. Moreover, The SBA-15-N-CoL1 showed high stability during four successive cycles.

Effect of surface modification on silica supported Ti catalysts for cyclohexene oxidation with vapor-phase hydrogen peroxide.

Surface modification via grafting of organic moieties on a Lewis acid catalyst (silica supported Ti catalyst, Ti-SiO2) alters the activation of H2O2 in vapor-phase cyclohexene epoxidation. Grafting a fluorous group (1H,1H-perfluoro-octyl) suppresses activity of Ti-SiO2. Conversely, grafting either a nonpolar group (octyl) or a polar aprotic group (triethylene glycol monomethyl ether) enhances rates and shifts selectivity toward trans-1,2-cyclohexanediol.

Terpolymerizations of cyclohexene oxide, CO2, and isocyanates or isothiocyanates for the synthesis of poly(carbonate–urethane)s or poly(carbonate–thioimidocarbonate)s

Terpolymerization of cyclohexene oxide (CHO), CO2, and aryl isothiocyanates produced poly(carbonate–thioimidocarbonate)s with gradient character, while that of CHO, CO2, and aryl isocyanates furnished poly(carbonate–urethane)s with random sequences.

Cd(ii) and Zn(ii) coordination polymer-assisted CO2/cyclohexene oxide copolymerization with a double metal cyanide catalyst

Three new coordination polymers with Zn(ii) and Cd(ii) metal centers were synthesized and applied to cocatalyze CO2/CHO polymerization with DMC.

Exploring enantiopure zinc-scorpionates as catalysts for the preparation of polylactides, cyclic carbonates, and polycarbonates.

New and simple ligand design strategies for the preparation of versatile metal-based catalysts capable of operating under greener and eco-friendly conditions in several industrially attractive processes are in high demand for society development. We present the first nucleophilic addition of an organolithium to ketenimines which incorporates a stereogenic centre in an N-donor atom to prepare new enantiopure NNN-donor scorpionates. We have also verified its potential utility as a valuable scaffold for chirality induction through the preparation of inexpensive, non-toxic and asymmetric zinc complexes. The pro-ligands and the corresponding zinc-based complexes have been characterized by X-ray diffraction studies. DFT studies were carried out to rationalize the different complexation abilities of these pro-ligands. These complexes have proved to act as highly efficient catalysts for a variety of sustainable bioresourced processes that are industrially attractive, with a wide substrate scope. Thus, complex 7 behaves as a highly efficient initiator for the well-behaved living ring-opening polymerization (ROP) of rac-lactide under very mild conditions. The PLA materials produced exhibited enhanced levels of isoselectivity, comparable to the highest value reported so far for zinc-based catalysts (Pi = 0.88). In addition, the combination of 7 with onium halide salts functioned as a very active and selective catalyst for CO2 fixation into five-membered cyclic carbonates through the cycloaddition of CO2 into epoxides under very mild and solvent-free conditions, reaching very good to excellent conversions (TOF = 227 h-1). Furthermore, this bicomponent system exhibits a broad substrate scope and functional group tolerance, including mono- and di-substituted epoxides, as well as the very challenging bio-renewable tri-substituted terpene-derived cis/trans-limonene oxide, whose reaction proceeds with high stereoselectivity. Finally, complex 7 also achieved high activity and selectivity as a one-component initiator for the synthesis of poly(cyclohexene carbonate)s via ring-opening copolymerization (ROCOP) of cyclohexene oxide and CO2 under very soft conditions, affording materials with narrow dispersity values.

Automatic Potential Energy Surface Exploration by Accelerated Reactive Molecular Dynamics Simulations: From Pyrolysis to Oxidation Chemistry.

Automatic potential energy surface (PES) exploration is important to a better understanding of reaction mechanisms. Existing automatic PES mapping tools usually rely on predefined knowledge or computationally expensive on-the-fly quantum-chemical calculations. In this work, we have developed the PESmapping algorithm for discovering novel reaction pathways and automatically mapping out the PES using merely one starting species is present. The algorithm explores the unknown PES by iteratively spawning new reactive molecular dynamics (RMD) simulations for species that it has detected within previous RMD simulations. We have therefore extended the RMD simulation tool ChemTraYzer2.1 (Chemical Trajectory Analyzer, CTY) for this PESmapping algorithm. It can generate new seed species, automatically start replica simulations for new pathways, and stop the simulation when a reaction is found, reducing the computational cost of the algorithm. To explore PESs with low-temperature reactions, we applied the acceleration method collective variable (CV)-driven hyperdynamics. This involved the development of tailored CV templates, which are discussed in this study. We validate our approach for known pathways in various pyrolysis and oxidation systems: hydrocarbon isomerization and dissociation (C4H7 and C8H7 PES), mostly dominant at high temperatures and low-temperature oxidation of n-butane (C4H9O2 PES) and cyclohexane (C6H11O2 PES). As a result, in addition to new pathways showing up in the simulations, common isomerization and dissociation pathways were found very fast: for example, 44 reactions of butenyl radicals including major isomerizations and decompositions within about 30 min wall time and low-temperature chemistry such as the internal H-shift of RO2 → QO2H within 1 day wall time. Last, we applied PESmapping to the oxidation of the recently proposed biohybrid fuel 1,3-dioxane and validated that the tool could be used to discover new reaction pathways of larger molecules that are of practical use.

The study on distribution coefficient of polonium between tri-octylphosphine oxide (TOPO) and tri-butylphosphate (TBP) in toluene and cyclohexane and selected inorganic acids

In this work the distribution coefficients (D) of polonium between 0.1 mol dm−3 TOPO/toluene; TOPO/cyclohexane; TBP/toluene and TBP/cyclohexane and aqueous solutions of inorganic acids (HCl, HNO3, H2SO4 and H3PO4) were determinated. The molarities of inorganic acids were between 0.5 and 12.0 mol dm−3. The activity of extracted Po-209 was measured by means of liquid scintillation counting. The best result was obtained for TOPO/toluene and 2 mol dm−3 H2SO4 system (D = 62 ± 9). The most stable conditions of extraction were found for TOPO/toluene-HCl system.