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The development of efficient catalyst for the epoxidation of alkenes is crucial in industrial application. Herein, bismuth molybdate samples with different surface properties (BMO-x, x = A, B, and C) were synthesized via a hydrothermal method and tested in cyclohexene epoxidation. The BMO-A catalyst exhibited superior catalytic activity, achieving a 67.3% cyclohexene conversion with 83.6% epoxide selectivity, outperforming the BMO-B (17.4% conversion, 40.2% selectivity) and BMO-C (27.0% conversion, 59.1% selectivity) catalysts. This enhanced activity is attributed to BMO-A's higher percentage of surface exchangeable oxygen, high surface Mo/Bi ratio, and optimal surface wettability. The high epoxidation performance of the BMO-A catalyst was attributed to its larger percentage of surface exchangeable oxygen, high surface Mo/Bi ratio, and suitable surface wettability. Specifically, the BMO-A with more exchangeable oxygen facilitated the adsorption of H2O2 molecules, and subsequent reaction with cyclohexene to yield epoxy-cyclohexane. The hydrophilic surface of BMO-A further enhanced H2O2 enrichment at the reaction interface. This work provides a new strategy for preparing highly active catalyst for the epoxidation of alkenes. [ABSTRACT FROM AUTHOR]

In this work, highly dispersed cobalt oxide nanoparticles on SiO2 support were prepared by a facile impregnation method and explored for aerobic selective oxidation of cyclohexene to 2-cyclohexene-1-one under base-free conditions. Among various compositions of Co3O4/SiO2 catalysts (0.5 to 5 wt% Co3O4) investigated, a 1 wt% Co3O4/SiO2 catalyst showed superior cyclohexene conversion with excellent selectivity to 2-cyclohexene-1-one. The synthesized catalysts were characterized by various physiochemical techniques namely, powder XRD, N2 physisorption, Raman spectroscopy, UV–Vis DRS, FTIR spectroscopy, XPS, FE-SEM, and HR-TEM. As revealed by various characterization results, the 1 wt% Co3O4/SiO2 catalyst shows better catalytic performance due to a more specific surface area and a high dispersion of Co3O4 nanoparticles on the SiO2 surface. Various reaction parameters like temperature, reaction time, amount of catalyst, oxidant, and solvent were also studied to optimize the reaction conditions. Further, the reusability of the catalyst was also tested up to five cycles and found to be stable with a negligible variation in the activity. [ABSTRACT FROM AUTHOR]

Here, a molecular semiconductor composite was assembled by integrating atomically precise Ti12-oxo clusters and phosphotungstic acid (PTA) into a cocrystal system. A molecular heterojunction was demonstrated to form between the two units, which allows the charge separation efficiency to be enhanced, resulting in a two-fold increase in photocatalytic activity for cyclohexene oxidation compared to the physically mixed composite. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

The Kirsanov reaction has been used to synthesise air stable, efficient and selective bifunctional aminophosphonium catalysts for the alternating ring-opening copolymerisation of cyclohexene oxide and phthalic anhydride without the need for a co-initiator. [ABSTRACT FROM AUTHOR]

One possible way to store the excess CO2 present in atmosphere is to use it as a reagent for the synthesis of commodities. In particular, CO2 and epoxides can be copolymerized to produce a large variety of polycarbonates which appear very promising in various application fields. Further, the addition of an appropriate transfer agent in the reaction mixture promotes the formation of telechelic polycarbonates which can be used where specific functional polymers are necessary. In this work, (hydroxyethyl) methacrylate and 2‐hydroxyethyl‐2‐bromoisobutyrate species are exploited as transfer agents in the copolymerization of CO2 and cyclohexene oxide, in the presence of a macrocyclic phenolate dimagnesium catalyst. The effect of the transfer agent concentration on the polycarbonate characteristics is evaluated. Finally, the obtained telechelic polycarbonates are used as macromonomers and macroinitiators in the synthesis of statistical and block copolymers. [ABSTRACT FROM AUTHOR]

In the production of cyclohexene by benzene hydrogenation, the by-product cyclohexane forms an azeotrope with cyclohexene. For the extraction and distillation of the binary azeotrope (cyclohexene + cyclohexane), the selectivity and relative volatility of 24 different entrainers were compared and the intermolecular interaction forces and interaction energies were analyzed by the DMol3 module of Materials Studio (MS). N, N-dimethylformamide (DMF) was identified as the entrainer, and vapour–liquid equilibrium (VLE) data were measured at atmospheric pressure for the binary system {cyclohexane + cyclohexene} with a temperature range of 354 K to 356 K, the binary system {cyclohexane + DMF} with a temperature range of 354 K to 390 K, and the binary system {cyclohexene + DMF} with a temperature range of 357 K to 421 K. In addition, the thermodynamic consistency of the experimental data was checked using the Wisniak and Van Ness method. The Wilson, NRTL, and UNIQUAC models were used to regress and fit the experimental data to optimize the binary interaction parameters, and the root mean square (RMSD) and average absolute deviation (AAD) values of all models were below 0.01%, indicating that the experimental data provide a basis for the simulation and optimization of the extractive distillation process. [ABSTRACT FROM AUTHOR]

Aerobic oxidation of olefins without any co‐reductant and high temperature was studies in the presence of nano and bulky Fe‐porphyrin in a comparative manner. Nano‐particles of Fe‐porphyrin were obtained via ultrasound irradiation. The results show higher catalytic efficiency of nano‐catalyst (turnover number of 1300) with respect to the bulk catalyst (turnover number of 600) in the oxidation of cyclohexene with molecular oxygen at room temperature. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An efficient synthesis of cyclohexenes has been achieved from easily accessible tetrahydropyrans via a tandem 1,5-hydride shift-aldol condensation. We discovered that readily available aluminium reagents, e.g. Al2 O3 or Al(Ot Bu)3 are essential for this process, promoting the 1,5-hydride shift with complete regio- and enantiospecificity (in stark contrast to results obtained under basic conditions). The mild conditions, coupled with multiple methods available to access the tetrahydropyran starting materials makes this a versatile method with exceptional functional group tolerance. A wide range of cyclohexenes (>40 examples) have been prepared, many in enantiopure form, showing our ability to selectively install a substituent at each position around the newly forged cyclohexene ring. Experimental and computational studies revealed that aluminium serves a dual role in facilitating the hydride shift, activating both the alkoxide nucleophile and the electrophilic carbonyl group.

Background: The production of alkenes as by-products of the oil industry, which poses a threat to public health and natural components of the environment. To prevent negative impacts, these volatile organic compounds (VOCs) must be converted into safe, useful products like epoxides. In addition, this process must be environmentally friendly and energy-efficient. Photoepoxidation of cyclohexene in the gas phase using H2 and O2 gases as redox agents can solve this problem. However, the effectiveness of the process must be studied. Objectives: The purpose is to investigate the effectiveness of using cyclohexene photocatalysis as an environmentally friendly, low-energy process for the production of epoxides in the gas phase using H2 and O2 gases as redox agents. It is also expected to obtain a low-cost, efficient process with the ability to control the reaction products. Methods: Titanium dioxide (TiO2) and Titanium silicate (TS-1) were prepared using sol gel and wetness impregnation, and used as photocatalysts. Results: Stable production of cyclohexene oxide was achieved with the TS-1 while only total mineralisation to CO2 was achieved with the TiO2. The kinetic analysis conducted here showed that the gas-phase reaction mechanism follows the Eley–Rideal mechanism. Gas-phase cyclohexene reacted directly with the intermediate formed through reaction between Ti base and the hydroperoxyl species, to produce cyclohexene oxide. Thus, this step was considered the rate-determining step. The effect of temperature was investigated at various partial pressures of individual gas reactant. An approximate value of 31 kJ/mol of activation energy was achieved. No epoxide was produced in the absence of H2 under the experimental conditions studied here. Total mineralisation of cyclohexene to CO2 was observed when O2 was used alone in the system. Conclusions: The results obtained in this work revealed that utilizing H2 and O2 for various oxidation reactions at elevated temperatures is possible.

[(Bn-tpen)FeII(MeCN)](ClO4)2, containing the pentadentate Bn-tpen–N-benzyl-N,N′,N′-tris(2-pyridylmethyl)-1,2-diaminoethane ligand, was studied in the oxygenation of cyclohexene and limonene using low-pressure dioxygen (0.2 atm air or 1 atm pure O2) in acetonitrile. 2-Cyclohexen-1-one and 2-cyclohexen-1-ol are the main products of cyclohexene oxidations, with cyclohexene oxide as a minor product. Limonene is oxidized to limonene oxide, carvone, and carveol. Other oxidation products such as perillaldehyde and perillyl alcohol are found in trace amounts. This catalyst is slightly less active than the previously reported [(N4Py)FeII(MeCN)](ClO4)2 (N4Py–N,N-bis(2-pyridylmethyl)-N-(bis-2-pyridylmethyl)amine). Based on cyclic voltammetry experiments, it is postulated that [(Bn-tpen)FeIV=O]2+ is the active species. The induction period of approx. 3 h during cyclohexene oxygenation is probably caused by deactivation of the reactive Fe(IV)=O species by the parent Fe(II) complex. Equimolar mixtures of Fe(II) salt and the ligand (in situ-formed catalyst) gave catalytic performance similar to that of the synthesized catalyst. [ABSTRACT FROM AUTHOR]

An efficient strategy for rapid assembly of the complex substituted cyclohexene core that is present in several cyclic imine marine toxins is presented. Several of these toxins, including pinnatoxin A and recently discovered portimine A, have been the focus of much attention due to their fascinating biological activities. We demonstrate that the substituted cyclohexene-diene motif, which is a challenging feature to access synthetically, can be prepared through a stepwise Ireland–Claisen rearrangement/enyne metathesis procedure beginning from chiral esters. This approach enables a divergent strategy that can be implemented in syntheses of cyclic imines or derivatives thereof. [ABSTRACT FROM AUTHOR]

Heterogeneously catalyzed liquid oxidation of olefins with O2 provides an alternative way for synthesizing high-value added chemicals. Herein, we report a straightforward urea-redox and sol-gel process for synthesizing LaCoxCu1−xO3 for aerobic photo-oxidation of cyclohexene. Our research highlights a marked increase in the proportions of Co2+ and Cu+ species in a low chemical state, as well as enhanced visible light absorption through this method. Mechanistic investigations suggest that the catalytic process, particularly with LaCo0.7Cu0.3O3, involves a radical pathway mediated by reactive oxygen species. The presence of Cu+/Co2+ species and surface oxygen vacancies is proposed to boost O2 adsorption and activation on the catalyst, facilitating the formation of 2-cyclohexene-1-hydroperoxides. Furthermore, Cu2+/Co3+ species are thought to aid in generating cyclohexene-derived radical species. The efficient aerobic oxidation of cyclohexene on LaCo0.7Cu0.3O3 catalyst relies on the formation of reactive oxygen species and carbon radicals, facilitated by its strong visible light illumination. It achieves a cyclohexene conversion of 89.4% and selectivity to cyclohex-2-ene-1-one of 72.2%, along with stable recyclability after six reuses. The creation of nano-structured LaCoxCu1−xO3 through the urea-redox and sol-gel process offers a promising avenue for the development of highly efficient catalysts for the aerobic photo-oxidation of cyclohexene to cyclohex-2-ene-1-one in the future. [ABSTRACT FROM AUTHOR]

Here, we develop a new absorbent for efficient separation of cyclohexanol (CHA-ol) and cyclohexene (CHA-ene) by using crystals of pillar[6]arene with three benzoquinone units (P3QA). P3QA crystals are found to show remarkable selectivity for CHA-ol in 50 : 50 (v/v) CHA-ol : CHA-ene mixtures with a purity of 95.2%, along with vapochromic behavior. [ABSTRACT FROM AUTHOR]

Aim: Shikimic acid is a hydroaromatic intermediate in the amino acid biosynthesis pathway in bacteria, fungi, and plants. Shikimic acid is an essential agent in applied sciences, especially in pharmacy and medicine. It can be used as a reactant in organic synthesis to obtain various medicinal drugs. This study aims to evaluate the antibacterial and antifungal properties of shikimic acid comparatively and to determine the minimum inhibitory concentrations (MIC) of shikimic acid against the tested Candida and bacterial species. Materials and Methods: The inhibitory effect of pure (98.85%) shikimic acid was tested on five bacteria (two Gram-positive and three Gram-negative) and five Candida species. The broth two-fold microdilution method was used to determine the MIC values against the tested microorganisms, and the viability of microorganisms treated with shikimic acid was determined using resazurin sodium salt. Results: The MIC values of shikimic acid against Candida glabrata, Candida albicans, Candida krusei, Candida tropicalis and Candida parapsilosis were determined to be between 250 and 31.25 mg/mL. However, the MIC values against bacterial species, including Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Enterobacter aerogenes, ranged between 15.625 and 3.906 mg/mL. Therefore, the antibacterial effect of shikimic acid is almost twenty times stronger than its antifungal effect. Conclusion: This preliminary study shows that shikimic acid is also usable as an antibacterial and antifungal as a potential therapeutic agent in addition to its proven antiviral properties. Further, advanced studies in this sense will be eye-opening. [ABSTRACT FROM AUTHOR]

Twelve polyoxygenated cyclohex(a/e)ne diterpene esters, named albiflorenes A–L (1–12), were isolated from the whole plants of Kaempferia albiflora, known as "Prao Mang Mum." Their structures and relative stereochemistry were determined by extensive spectroscopic analysis. Furthermore, the comparison of experimental electronic circular dichroism (ECD) curves with the curves predicted by TDDFT was used to determine the absolute configurations. Albiflorenes contain polyoxygenated cyclohexane (or cyclohexene) derivatives, which are linked to either isopimarane or abietane diterpene acid units. The discovery marks the first occurrence of a conjugate between polyoxygenated cyclohexane (or cyclohexene) rings and diterpenoids. Among the isolates, albiflorene C specifically exhibited antibacterial activity against Bacillus cereus with MIC and MBC values of 3.13 and 6.25 μg/mL, respectively. [ABSTRACT FROM AUTHOR]

It is found that the reaction of dimethyl 2-phenylcyclopropane-1,1-dicarboxylate with 2 equivalents each of aromatic aldehydes and TaCl5 in 1,2-dichloroethane at 23 °C for 24 h after hydrolysis gives substituted 4-phenyl-3,4-dihydronaphtalene-2,2(1H)-dicarboxylates in good yield. This represents a new type of reactions between 2-arylcyclopropane-1,1-dicarboxylates and aromatic aldehydes, yielding chlorinated tetrahydronaphthalenes with a cis arrangement of the aryl and chlorine substituents in the cyclohexene moiety. A plausible reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

The effects of the p-toluenesulfonic acid monohydrate (TsOH∙H2O) concentration on the alkoxycarbonylation of cyclohexene over a Pd(PPh3)2Cl2–PPh3–TsOH∙H2O catalytic system were quantified at 363–383 K. Within this temperature range, the correlation between the cyclohexyl cyclohexanecarboxylate production rate and the TsOH∙H2O concentration was found to be similar to an S-shaped curve. Based on these data, as well as previous findings with regard to the effects of water and TsOH∙H2O concentrations on the cyclohexene methoxycarbonylation rate, the hydride mechanism for the alkoxycarbonylation process was updated by adding relevant ligand exchange reactions between ballast palladium complexes, specifically reactions that produce a palladium aqua complex. The accordingly-modified kinetic equation for cyclohexene alkoxycarbonylation with cyclohexanol and CO was found to be consistent with the experimental data. Effective constants were evaluated for the modified kinetic equation over the studied temperature range. A number of relevant parameters—namely, the effective activation energy and the changes in enthalpy, entropy, and Gibbs free energy during the ligand exchange between the complexes Pd(PPh3)2(C6H11OH)2 and Pd(PPh3)2(H2O)2—were further evaluated in light of the activated complex theory. This reaction was found to be nearly equilibrium at 373 K. [ABSTRACT FROM AUTHOR]

The effect of particle size and support on the catalytic performance of supported subnanometer copper clusters was investigated in the oxidative dehydrogenation of cyclohexene. From among the investigated seven size-selected subnanometer copper particles between a single atom and clusters containing 2–7 atoms, the highest activity was observed for the titania-supported copper tetramer with 100% selectivity toward benzene production and being about an order of magnitude more active than not only all the other investigated cluster sizes on the same support but also the same tetramer on the other supports, Al2O3, SiO2, and SnO2. In addition to the profound effect of cluster size on activity and with Cu4 outstanding from the studied series, Cu4 clusters supported on SiO2 provide an example of tuning selectivity through support effects when this particular catalyst also produces cyclohexadiene with about 30% selectivity. Titania-supported Cu5 and Cu7 clusters supported on TiO2 produce a high fraction of cyclohexadiene in contrast to their neighbors, while Cu4 and Cu6 solely produce benzene without any combustion, thus representing odd–even oscillation of selectivity with the number of atoms in the cluster. [ABSTRACT FROM AUTHOR]

The synthesis and structural characterization of an electron poor Au(III) trication bearing 2 imidazole and 2 acetonitrile ligands is described. The new complex is capable of aryl C–H metalation with the formation of a monomesitylene complex and also demonstrated to be highly oxidizing in the rapid room temperature conversion of cyclohexene to benzene. [ABSTRACT FROM AUTHOR]

Dearomative partial reduction is an extraordinary approach for transforming benzenoid arenes and has been well‐known for many decades, as exemplified by the dehydrogenation of Birch reduction and the hydroarylation of Crich addition. Despite its remarkable importance in synthesis, this field has experienced slow progress over the last half‐century. However, a revival has been observed with the recent introduction of electrochemical and photochemical methods. In this Minireview, we summarize the recent advancements in dearomative partial reduction of benzenoid arenes, including dihydrogenation, hydroalkylation, arylation, alkenylation, amination, borylation and others. Further, the intriguing utilization of dearomative partial reduction in the synthesis of natural products is also emphasized. It is anticipated that this Minireview will stimulate further progress in arene dearomative transformations. [ABSTRACT FROM AUTHOR]

The fruit of Choerospondias axillaris (Anacardiaceae), known as south wild jujube in China, has been consumed widely in several regions of the world to produce fruit pastille and leathers, juice, jam, and candy. A comprehensive chemical study on the fresh fruits led to the isolation and identification of 18 compounds, including 7 new (1–7) and 11 known (8–18) comprised of 5 alkenyl (cyclohexenols and cyclohexenones) derivatives (1–5), 3 benzofuran derivatives (6–8), 6 flavonoids (9–14) and 4 lignans (15–18). Their structures were elucidated by extensive spectroscopic analysis. The known lignans 15–18 were isolated from the genus Choerospondias for the first time. Most of the isolates exhibited significant inhibitory activity on α-glucosidase with IC50 values from 2.26 ± 0.06 to 43.9 ± 0.96 μM. Molecular docking experiments strongly supported the potent α-glucosidase inhibitory activity. The results indicated that C. axillaris fruits could be an excellent source of functional foods that acquire potential hypoglycemic bioactive components. [ABSTRACT FROM AUTHOR]

High-performance hydrogenation catalysts are crucial for integrating hydrogen production and storage in organic/water systems, as well as for CO2 electrocatalytic reduction reactions. In this study, ion beam sputtering, coupled electrochemical de-alloying, and hot pressing have been employed to fabricate an SPE membrane electrode containing porous AuTiCeOx/NC. Characterization techniques were utilized to analyze and discuss the phase composition, surface morphology, components, exposed crystal faces, and their relationship with the catalytic efficiency and reaction stability of the Au-based SPE membrane electrode during the hydrogenation of cyclohexene. The results revealed that the membrane electrode carrier is composed of hexagonal phase C3N4, the Au-based catalyst possesses tetragonal Au2Ti and face-centered cubic Au phases, and Ce exists as amorphous ceria at the grain boundary; electrochemical de-alloying treatment yielded uniform elemental distribution and mesopores with an average pore size of < 10 nm; the binding energy of Au's 4f reduced by 0.17 eV, the Au–Au distance decreased the interplanar spacings of Au2Ti {112} and {103} shrank by approximately 6.8% and 5.8%, respectively, and a new high-index surface (105) emerged; the cyclohexane generation rate and the current efficiency in the hydrogenation reaction of cyclohexene increased by 7.92% and 14.14% respectively. [ABSTRACT FROM AUTHOR]

A series of novel amine triphenolate iron complexes were synthesized and characterized using UV, IR, elemental analysis, and high-resolution mass spectrometry. These complexes were applied to the ring-opening polymerization (ROP) of cyclohexene oxide (CHO), demonstrating excellent activity (TOF > 11050 h−1) in the absence of a co-catalyst. In addition, complex C1 maintained the dimer in the presence of the reaction substrate CHO, catalyzing the ring-opening polymerization of CHO to PCHO through bimetallic synergy. Furthermore, a two-component system consisting of iron complexes and TBAB displayed the ability to catalyze the reaction of CHO with CO2, resulting in the formation of cis-cyclic carbonate with high selectivity. Complex C4 exhibited the highest catalytic activity, achieving 80% conversion of CHO at a CHO/C4/TBAB molar ratio of 2000/1/8 and a CO2 pressure of 3 MPa for 16 h at 100 °C, while maintaining >99% selectivity of cis-cyclic carbonates, which demonstrated good conversion and selectivity. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Zhengzhou University (Natural Science Edition) is the property of Journal of Zhengzhou University (Natural Science Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The development of the zeolite molecular sieves (ZSM-5) molding technique is essential for the cyclohexene hydration reaction distillation process in both industrial and research settings. The reactive distillation process can solve many of the drawbacks associated with the existing technique of manufacturing cyclohexanol via cyclohexene hydration, such as high catalyst digestibility, low conversion rate, and operational challenges. This study developed a series of molded ZSM-5 catalysts with various binder types and contents were constructed. The suggested pseudo-boehmite and hydroxypropyl methylcellulose were chosen as binders for extrusion molding of ZSM-5. The effects of binders on the strength reliability were investigated by strength tests and statistical analysis of the Weibull function. The effects of binders on the physical structure, acidity, and catalytic performance of ZSM-5 were investigated by X-ray diffraction, scanning electron microscopy, physical adsorption of N2, and desorption of NH3. The findings demonstrate that the addition of binder has no effect on ZSM-5's crystal structure. The experiment's results showed that the molded catalyst could be used for the hydration process with over 95% selectivity and a yield of 10.45% cyclohexanol. [ABSTRACT FROM AUTHOR]

The synthesis of nylon 6 and nylon 66 can be performed, starting with the selective hydrogenation of benzene to cyclohexene, which is deemed to be environmentally friendly and cost-saving and to have higher atom efficiency. Nano-Ru catalyst was synthesized via a precipitation method. The prepared catalyst was evaluated in the selective hydrogenation of benzene toward cyclohexene generation in the presence of ZnSO4 in a liquid batch reactor. The promotion effect of the addition of amines, i.e., ethylenediamine, ethanolamine, diethanolamine, and triethanolamine, was investigated. The fresh and spent catalysts were thoroughly characterized by XRD, TEM, AES, N2-sorption, FT-IR, and TPR. It was found that the addition of amines could significantly improve the catalytic selectivity toward cyclohexene formation in the presence of ZnSO4. This was attributed to the formation of (Zn(OH)2)5(ZnSO4)(H2O)x (x = 0.5, 3 or 4) through the reaction between ZnSO4 and the amines, which could be chemisorbed on the Ru surface. This led to retarding the formation of cyclohexane from the complete hydrogenation of benzene and, thus, increased the catalytic selectivity toward cyclohexene synthesis. Therefore, with the presence of ZnSO4, the amount of chemisorbed (Zn(OH)2)5(ZnSO4)(H2O)x increased with increasing amounts of added amines, leading to a decline in the catalytic activity toward benzene conversion and selectivity toward cyclohexene generation. When 7.6 mmol of diethanolamine and 10 g of ZrO2 were applied, the highest cyclohexene yields of 61.6% and 77.0% of benzene conversion were achieved over the Ru catalyst. Promising stability was demonstrated after six runs of catalytic experiments without regeneration. These achievements are not only promising for industrial application but also beneficial for designing other catalytic systems for selective hydrogenation. [ABSTRACT FROM AUTHOR]

When considering the usage of ionic liquids (ILs) for reactions and separations involving non-polar or weak-polar hydrocarbons, the knowledge of the mutual solubility behaviors of ILs and hydrocarbons is of the utmost importance. In this work, taking four typical C6-hydrocarbons namely benzene, cyclohexene, cyclohexane, and hexane as representatives, the mutual solubility of ILs and non-polar or weak-polar hydrocarbons are systematically studied based on the COSMO-RS model. The reliability of COSMO-RS for these systems is first evaluated by comparing experimental and predicted hydrocarbon-in-IL activity coefficient at infinite dilution and binary/ternary liquid-liquid equilibria of related systems. Then, the mutual solubility of the four hydrocarbons and 13,650 ILs (composed by 210 cations and 65 anions) are predicted. The effect of different IL structural characteristics including alkyl chain length, cation family/symmetry/functional group, and anion on the IL-hydrocarbon mutual solubility behaviors are further analyzed by the analyses of interaction energy and screen charge distribution. The mutual solubility databases and the structural effects identified thereon could provide useful guidance for IL selection in related applications. [ABSTRACT FROM AUTHOR]

Objectives. To investigate the regularities of the process of joint production of epoxycyclohexane, cyclohexanol, and cyclohexanone using the cyclohexene epoxidation reaction with cyclohexyl hydroperoxide in the presence of an ammonium paramolybdate catalyst, representing an alternative to the method of cyclohexanol and cyclohexanone synthesis by alkaline catalytic decomposition of cyclohexyl hydroperoxide.Methods. The qualitative and quantitative analysis of the obtained intermediate and target compounds was determined using modern physicochemical research methods: gas–liquid chromatography using the Chromatec-Crystal 5000.2 hardware and software complex with a flame ionization detector and infrared spectroscopy on an RX-1 infrared Fourier spectrometer. The content of hydroperoxide in the oxidation products was determined using iodometric titration, while the carboxylic acid content was determined by the titrimetric method based on the neutralization reaction.Results. The presented method for obtaining cyclohexanol and cyclohexanone together with epoxycyclohexane by the reaction of cyclohexene epoxidation with cyclohexyl hydroperoxide containing cyclohexane in the products of high-temperature liquid-phase oxidation is experimentally substantiated. The influence of various technological parameters on the process of liquid-phase oxidation of cyclohexane to hydroperoxide is described. The conditions for carrying out this reaction are determined to ensure the achievement of a content of cyclohexyl hydroperoxide of 1.5 wt % in the products of oxidation. The regularities of the epoxidation reaction of the synthesized cyclohexyl hydroperoxide with cyclohexene in the presence of an ammonium paramolybdate catalyst are analyzed.Conclusions. Epoxidation of cyclohexene with cyclohexyl hydroperoxide produced epoxycyclohexane at a yield of 80–90% and a conversion of cyclohexane hydroperoxide of 85%.

Cyclohexane (CHA), cyclohexene (CHE), and 1,4-cyclohexadiene (CHD) derivatives have a wide variety of applications and scope in synthetic and industrial organic chemistry. These cyclic hydrocarbons are found in a variety of natural products, including herbal plants and fruits as basic fragrance components. The extraction and isolation of these essential hydrocarbons are too complex and difficult to pursue. However, the reduction of benzene and its derivatives is an essential and effective approach for producing CHA, CHE, and CHD derivatives. To obtain CHA, CHE, and CHD derivatives, several types of reduction techniques for benzene and its derivatives have been developed over the years, including various forms of catalytic hydrogenation, Benkeser reduction, classic and many modified Birch reductions such as ammonia-free, metal-free photochemical, solvent-free, electrochemical and electride-mediated Birch reduction. In this study, the comparison of chemoselectivity, regioselectivity, reaction conditions, reduction efficiency, and environmentally acceptable approaches of these techniques used for benzene reduction are summarized. [ABSTRACT FROM AUTHOR]

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, qRTPCR 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 antitumor 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. [ABSTRACT FROM AUTHOR]

O,N-Heterocyclic phospholenes (tBuAp)PCl, (PhAp)PCl, (PhAp)PPh and (PhenoxAp)PCl based on sterically hindered 4,6-di-tert-butyl-N-(R)-о-aminophenols (RAp, R = tBu, Ph) and 2,4,6,8-tetra-tert-butyl-1H-phenoxazin-1-one (PhenoxAp) were synthesized and structurally characterized. The diverse reactivity of the synthesized compounds towards reducing, oxidizing agents and Lewis acids was observed. Reduction of (tBuAp)PCl leads to a dimeric diphosphole. The oxidative addition of 3,6-di-tert-butyl-o-benzoquinone and 4,6-di-tert-butyl-N-(2,6-di-isopropyl-phenyl)-o-iminoquinone to the phosphorus in (PhAp)PCl gives new pentacoordinated PV compounds containing two different dianionic redox-active ligands. Bis-o-amidophenolate (PhenoxAp)2PBr was prepared by the reaction of 2,4,6,8-tetra-tert-butyl-1H-phenoxazin-1-one with PBr3 and cyclohexene. Dissolution of (PhenoxAp)2PBr in THF promotes the ring opening reaction of the cyclic ether. The reaction of (PhAp)PCl with Ni(CO)4 and Fe2(CO)9 leads to the stable PIII adducts (PhAp)P(Cl)–Ni(CO)3 and (PhAp)P(Cl)–Fe(CO)4. [ABSTRACT FROM AUTHOR]

Ultrafast tunnel ionization enables femtosecond time-resolved dynamic measurements of the retro-Diels–Alder reactions of positively charged cyclohexene, norbornene, and dicyclopentadiene. Unlike the reaction times of 500–600 ps that are observed following UV excitation of neutral species, on the ionic potential energy surfaces, these reactions occur on a single picosecond timescale and, in some cases, exhibit vibrational coherence. In the case of norbornene, a 270 cm−1 vibrational mode is found to modulate the retro-Diels–Alder reaction. [ABSTRACT FROM AUTHOR]

Cyclohexane epoxide, which contains highly active epoxy groups, plays a crucial role as an intermediate in the preparation of fine chemicals. However, controlling the epoxidation pathway of cyclohexene is challenging due to issues such as the allylic oxidation of cyclohexene and the ring opening of cyclohexane epoxide during the cyclohexene epoxidation process to form cyclohexane oxide. This review focuses on the structure‐activity relationships and synthesis processes of various heterogeneous transition metal‐based catalysts used in cyclohexene epoxidation reactions, including molybdenum(Mo)‐based, tungsten(W)‐based, vanadium(V)‐based, titanium(Ti)‐based, cobalt(Co)‐based, and other catalysts. Initially, the mechanism of cyclohexene epoxidation by transition metal‐based catalysts is examined from the perspective of catalytic active centers. Subsequently, the current research of cyclohexene epoxidation catalysts is summarized based on the perspective of catalyst support. Additionally, the differences between alkyl hydroperoxide, hydrogen peroxide (H2O2), and oxygen (O2) as oxidants are analyzed. Finally, the main factors influencing catalytic performance are summarized, and reasonable suggestions for catalyst design are proposed. This work provides scientific support for the advancement of the olefin epoxidation industry. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAP) contains abundant defect sites and easily releases hydroxyl groups to produce new vacancies under calcination at high temperature. The highly dispersed VOx/HAP catalyst was prepared by an impregnation method using these defects as inducement. VOx species with different structures were analysed by XRD, XPS, H2‐TPR, Raman and UV–vis spectroscopy. At low calcination temperatures (500 °C and 600 °C), the V species are mainly V2O5 crystals. At high calcination temperatures (above 700 °C), VOx on the HAP surface fills these defect sites and strongly interacts with HAP to form Ca−O−V or P−O−V bands. These scattered defects improved the dispersion of V species. These highly dispersed VOx/HAP catalysts were used for oxidative dehydrogenation (ODH) of cyclohexane to cyclohexene. The highly dispersed VOx/HAP catalyst showed a high selectivity for cyclohexene, and the selectivity reached 48.2 % when the conversion of cyclohexane was 13.1 % at 410 °C. [ABSTRACT FROM AUTHOR]

In this paper, reinforced porous Pt-based alloy SPE membrane electrodes were synthesized by using ion beam sputtering, combinatorial electrochemical acid etching, and hot-pressing technology. The influences of combinatorial electrochemical acid etching on the phase structure, geometric specific surface area (SSA), electrochemical surface area (ESA), surface morphology, chemical state, exposed crystal surface, and catalytic hydrogenation performance of a Pt-based alloy catalyst and SPE membrane electrodes were investigated. The results shown that the Pt-based alloy catalyst was composed of the body-centered orthogonal Pt5Ti3 phase and simple orthogonal PtTi phase with the Ce element dispersed at grain boundaries in the form of amorphous cerium oxide. On the surface, there were mesopores ranging from 3 to 15 nm in diameter, Pt-rich grains less than 10 nm in size, and a few polyhedral grains of 20–50 nm. The crystal plane spacings of the exposed (2 2 ¯ 0), (400), and (220) high-index crystal planes of the Pt5Ti3 phase showed some interplanar space shrinkage of 5–7%. The contribution of the geometric surface area of the Pt-based alloy catalyst to the ESA was up to 352.16%. The energy consumption of catalytic cyclohexene hydrogenation was reduced by 39.33%. The current efficiencies of cyclohexene hydrogenation and the cyclohexene conversion rate were increased by 41.40% and 132.65%, respectively. The reinforced porous Pt-based alloy SPE membrane electrodes have advantages such as short process synthesis with pure products, and high-index exposed crystal planes regulation, strong catalytic activity, and low energy consumption. [ABSTRACT FROM AUTHOR]

Thus, in the acidic atmosphere of the PEM electrolyzer, oxidation of the allyl moiety and the olefinic moiety of cyclohexene occurred concurrently and the oxidation products could not be selectively and efficiently synthesized at either potential or on either catalyst. The fact that this cyclohexene oxidation current was not observed on the unmodified Au catalyst anode (Figure S1 in SI) suggests that the cyclohexene is oxidized by reactive oxygen species formed on the Au catalyst. In potentiostatic bulk electrolysis using the PEM electrolyzer, oxidation of cyclohexene proceeded efficiently; however, there is competition between oxidation of the allylic and olefinic moieties of cyclohexene. Keywords: electrocatalytic oxidation; proton-exchange membrane electrolyzer; anion-exchange membrane electrolyzer; cyclohexene EN electrocatalytic oxidation proton-exchange membrane electrolyzer anion-exchange membrane electrolyzer cyclohexene 2979 2984 6 08/31/23 20230915 NES 230915 Graph Oxidation can be used as a synthetic tool to manufacture many chemical products and is therefore one of the most important reactions in the chemical industry. [Extracted from the article]

A new type of catalyst by metal loaded on UiO-66-NH2 was prepared by modification of UiO-66-NH2 and post-synthesis with salicylaldehyde and impregnation by transition metals (Co, Mn, Cr, and Cu) to catalyze oxidation of cyclohexene in liquid phase at high pressure condition. The reactions were carried out in a high pressure batch reactor in the presence of tert-butyl hydroperoxide (TBHP) as oxidant in different temperature and pressure. Results showed high catalytic activity for oxidation of cyclohexene (100%) in the high pressure conditions. Maximum selectivity was achieved using Mn/UiO-66-Sal for 2-cyclohexen-1-one production (70%) at T = 50°C and P = 2.2 bar. Other products were 2-cyclohexen-1-ol and cyclohexene 3‑(tert-butyl) peroxide. Analysis of the products showed that the reaction pathway proceeds allylic mechanism instead of epoxidation pathway. Catalytic selectivity for 2-cyclohexen-1-one followed as Mn > Cr > Co ≈ Cu. [ABSTRACT FROM AUTHOR]

Gold nanospecies produced by a historically inspired two-liquid phase system were immobilized on plate-like mesoporous silica, SBA-15, functionalized with mercaptopropyl groups by a post-synthesis method, and the resulting materials were tested in the oxidation of cyclohexene with molecular oxygen at atmospheric pressure. The main purpose of this approach was to compare the physicochemical properties and catalytic performance of these materials with those of previously reported related materials functionalized by in situ methods during synthesis. In addition, catalytic tests under ambient lighting and darkness and also in the presence and absence of the initiator tert-butyl hydroperoxide (TBHP) were carried out. The samples were characterized by chemical analysis, N2 adsorption/desorption, TGA, SEM, HRTEM, UV-vis spectroscopy and XPS. Gold nanoclusters and isolated gold atoms but no AuNPs were found in the catalysts (0.31–2.69 wt.% of gold). The XPS shows that nearly 60% of the -SH groups (1.33 wt.% of S) were oxidized to sulphonic groups upon gold immobilization. The AuNCs and isolated gold atoms evolved in the the reaction medium to form AuNPs. The activity of the samples was lower than that of the catalysts supported on related S-bearing SBA-15 functionalized in situ, which was attributed to their different Au/S ratios, which in turn regulated the evolutionary process of the gold species during the reaction. The catalysts turned out to be inactive in darkness, which evidences that the cyclohexene oxidation carried out at ambient illumination is actually photocatalyzed by the AuNPs formed in situ during the reaction. The TBHP initiator is required to obtain the activity in order to counteract the inhibitors of cyclohexene auto-oxidation present in the commercial reagent. On the other hand, no major differences in the selectivity among the different catalysts and reactions were observed, with 2-cyclohexen-1-one and 2-cyclohexen-1-ol resulting from the allylic oxidation as main products (selectivity of (one + ol) ~80% at a conversion ≥ 35%; one/ol~2).

While chain‐walking stimulates wide interest in both polymerization and organic synthesis, site‐ and stereoselective control of chain‐walking on rings is still a challenging task in the realm of organometallic catalysis. Inspired by a controllable chain‐walking on cyclohexane rings in olefin polymerization, we have developed a set of chain‐walking carboborations of cyclohexenes based on nickel catalysis. Different from the 1,4‐trans‐selectivity disclosed in polymer science, a high level of 1,3‐regio‐ and cis‐stereoselectivity is obtained in our reactions. Mechanistically, we discovery that the base affects the reduction ability of B2pin2 and different bases lead to different catalytic cycles and different regioselective products (1,2‐ Vs 1,3‐addition). This study provides a concise and modular method for the synthesis of 1,3‐disubstituted cyclohexylboron compounds. The incorporation of a readily modifiable boronate group greatly enhances the value of this method, the synthetic potential of which was highlighted by the synthesis of a series of high‐valued commercial chemicals and pharmaceutically interesting molecules. [ABSTRACT FROM AUTHOR]

Herein, we present a manganese‐catalyzed, branched‐selective hydroalkenylation of terminal alkynes, under mild conditions through facile installation of a versatile silanol as a removable directing group. With an alkenyl boronic acid as the coupling partner, this reaction produces stereodefined (E,E)‐1,3‐dienes with high regio‐, chemo‐ and stereoselectivity. The protocol features mild reaction conditions such as room temperature and an air atmosphere, while maintaining excellent functional group compatibility. The resulting 1,3‐dienesilanol products serve as versatile building blocks, as the removal of the silanol group allows for the synthesis of both branched terminal 1,3‐dienes for downstream coupling reactions, as well as stereoselective construction of linear (E,E)‐1,3‐dienes and (E,E,E)‐ or (E,E,Z)‐1,3,5‐trienes. In addition, a Diels–Alder cycloaddition can smoothly and selectively deliver silicon‐containing pentasubstituted cyclohexene derivatives. Mechanistic investigations, in conjunction with DFT calculations, suggest a bimetallic synergistic activation model to account for the observed enhanced catalytic efficiency and good regioselectivity. [ABSTRACT FROM AUTHOR]

The kinetics of the oxidation of CO to CO2 in the PdBr2–CuBr2–THF–H2O system outside the coupled process of cyclohexene hydrocarboxylation was studied. A kinetic model was constructed, and a reaction mechanism was proposed. It was found that the alkene hydrocarboxylation affects the oxidation of CO to CO2 in the coupled process, which was investigated previously. [ABSTRACT FROM AUTHOR]