Cyclohexene Epoxidation Reaction Research Articles

Epoxidation of cyclohexene with cyclohexyl hydroperoxide

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%.

An Overview of Heterogeneous Transition Metal‐Based Catalysts for Cyclohexene Epoxidation Reaction

AbstractCyclohexane 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.

Synthesis of ceria nanoparticles for the catalytic activity of cyclohexene epoxidation and selective detection of nitrite

Based on a few noteworthy features, cerium oxide nanoparticles have gained significance in nanotechnology. The effective microwave combustion method (MCM) and the conventional sol–gel (CRSGM) technologies are used in this study to successfully generate the crystalline CeO2 nanoparticles (NPs). Additionally, using a variety of spectroscopic and analytical methods, the synthesized CeO2 NPs are examined to assess to understand their structure and morphology. The XRD patterns of CeO2 NPs show that the structure exhibits a face-centered cubic lattice. Then, with demonstrated good conversion and selectivity, the impact of the epoxidation reaction of cyclohexene was examined. Finally, it can be said that using CeO2 nanoparticles is an efficient strategy to increase the catalytic activity toward the epoxidation reaction of cyclohexene. In the presence of acetonitrile as a solvent and H2O2 as an oxidant, the catalyst samples utilized in the cyclohexene epoxidation reaction were examined. In this study, the CeO2 catalyst outperformed all other catalysts in terms of cyclohexene maximal conversion and selectivity. After six prolonged cycles, the conversion of cyclohexene oxidation using CeO2 NPs shows reasonable recyclability and conversion efficiency, making it the best catalyst for an industrial production application.Additionally, the upgraded CeO2 nanoparticle electrode for nitrite detection has a linear concentration range (0.02–1200 M), a low detection limit (0.22 M), and a higher sensitivity (1.735 A M−1 cm−2). CeO2 NPs, on the other hand, have a quick response time, excellent sensitivity, and high selectivity. Additionally, the manufactured electrode is used to find nitrite in various water samples. Finally, it can be said that using CeO2 NPs is an efficient strategy to increase the catalytic activity toward cyclohexene oxidation and nitrite.

Influence of platinum on mordenite properties and catalytic activity towards cyclohexene epoxidation

The Pt-containing commercial mordenite catalyst that was synthesized having different Si/Al molar ratios (SAR) = 32, 40, and 50, and it was applied in the epoxidation reaction of cyclohexene. The samples were analysed and confirmed by various physicochemical techniques in powder X-ray diffraction (XRD) for identifying phases and planes, Brunauer-Emmett-Teller (BET) for determining textural properties, Fourier-transform infrared spectroscopy (FT-IR) for distinguishing functional groups, high resolution scanning electron microscopy (HR-SEM) for finding morphology, temperature-programmed desorption (TPD) to determine stability, and transmission electron microscopy (TEM) to identify microstructural details. The catalysts were tested for cyclohexene epoxidation reaction in the presence of H2O2as oxidant and acetonitrile as solvent. In this work, cyclohexene maximum conversion and selectivity is obtained with Pt/mordenite (40%) catalyst among the catalysts investigated. The conversion of cyclohexene oxidation recyclability of the Pt/Mordenite (40%) reveals reasonably acceptable conversion efficiency after six cycles, and the catalyst is found to be most suitable for an industrial production application.

Unsymmetrical salen nickel (II) complex embracing phenol bridge: X-ray structure, redox investigation, computational calculations, antimicrobial and catalytic activities

An exhaustive description of the crystal structure, DFT, TD-DFT and redox properties of a non-symmetrical nickel complex NiLOH, N,N’-2,3-hydroxyphenol -2,3-dyil-bis (salicylideneimine)nickel(II), are reported. The complex crystallizes, in the monoclinic crystal system, with P21/c space group. Oxygen-atom of the phenolic spacer contributes in hydrogen bonding forming a zigzag chain along a axis. Cyclic voltammetric study of the complex revealed a quasi-reversible process Ni(II)/Ni(I) on a glassy carbon electrode at E1/2 = -1371, -1312, -1305 mV/SCE in DMSO, CH3CN and DCM, respectively. From DFT calculations, the electronic properties of NiLOH complex and its reactivity with DNA bases, in polar and non-polar media, shows a good agreement with the experimental results. TD-DFT revealed that the absorption electronic states correspond to a mixture of metal to ligand charge transfer (d→π*) and intra-ligand charge transfer (π→π*) transitions. The NiLOH complex as catalyst proved to be catalytically active in the cyclohexene epoxidation reaction. The ligand and the NiLOH complex were scrutinized for their antibacterial activity in agar medium by the disk diffusion method against some Gram positive and Gram negative strains. Better inhibitory potential towards some examined bacteria was shown.

Imidazolium-based titanosilicate nanospheres as active catalysts in carbon dioxide conversion: Towards a cascade reaction from alkenes to cyclic carbonates

Porous silica-based nanospheres bearing titanium centres as single site were successfully synthesized employing a time- and energy-efficient procedure. The influence of the post-synthesis treatment on the insertion of Ti was investigated via DR UV–Vis and XPS spectroscopy and the titanium content was quantified through ICP-OES analysis. The textural and structural properties of the different solids were evaluated via XRD, TEM and N2 physisorption. The resulting materials were thereafter covalently functionalized with imidazolium chloride, followed by characterization via 29Si and 13C solid-state NMR, N2 physisorption and chemical combustion analysis. The bi-functional catalysts were tested in the challenging conversion of CO2 with cyclohexene oxide to the corresponding cyclic carbonate as well as with various other epoxides with excellent results. The insertion of Ti as single site played a key role substantially improving the activity of the solids. The most active bi-functional material was successfully recovered and reused through multiple cycle without loss of the catalytic activity. Moreover, the cyclohexene epoxidation reaction was tested as well employing the mono-functionalized Ti-based material. The catalytic mixture, composed by the mono-functional and bi-functional solids, was efficiently used to convert the cyclohexene into cyclohexene oxide and subsequently the cyclohexene oxide into the corresponding carbonate thus opening the prospect for a cascade reaction.

Instant Cyclohexene Epoxidation Over Ni-TUD-1 Under Ambient Conditions

To avoid the aggregation problem and activity loss of nickel oxide (NiO) nanoparticles (NPs) in organic reactions, NiO NPs were incorporated into TUD-1 mesoporous material. One-step sol–gel preparation was applied to prepare four samples of Ni incorporated in TUD-1 silica matrix with different Ni content. The four samples with Si/Ni ratio = 100, 50, 20, and 10 were characterized by means of elemental analysis, powder X-ray diffraction (XRD), Raman spectroscopy, N2 sorption measurements, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and high-resolution transmission electron microscopy (HR-TEM). The characterization analysis showed that Ni2+ ions were incorporated into the silica matrix as individual isolated active sites at Ni content smaller than 2 wt%, and as nanoparticles of NiO when the loading is equal to or higher than 5 wt%. The size of NiO NPs inside the silica matrix is highly dependent on the Ni content, i.e. the size of NiO NPs when the loading was 5 wt% and 10 wt% was 5–10 and 40–60 nm, respectively. The catalytic activity of Ni-TUD-1 was investigated in the epoxidation reaction of cyclohexene at room temperature by using meta-chloroperoxybenzoic acid (m-CPBA) as an oxidant. The obtained results showed that Ni-TUD-1 exhibited superior activity in which 100% conversion of cyclohexene with > 90% selectivity towards cyclohexene oxide was obtained instantly. This result was found to benchmark not only the unsupported NiO nanoparticles, but also the reported catalysts at similar conditions.

Regulation of framework titanium siting in MWW-type titanosilicates by boron and aluminum incorporation and its effect on the catalytic performance

Abstract The exploration of efficient catalysts with more accessible active titanium species based on the titanosilicate zeolites is in incremental demands for the construction of the high utilization active centers to the various reactions. Here, we report an active oxidation catalyst MWW-type titanosilicate (Al-Ti-MWW) with more “Ti” active species distributed on the zeolite surface obtained through the implantation of the heteroatom aluminum to the conventional Ti-MWW synthesis. Combined with the overall measurements, it was deduced that more “Ti” species were regulated to evenly distributed in the zeolite crystal, which was due to the competitive occupancy of the heteroatom Al, B and Ti over T locations. Consequently, the bulky-substrate reaction results such as the cyclohexene epoxidation reaction and cyclohexanone ammoximation reaction showed that the Al-Ti-MWW catalyst had a superior catalytic oxidation activity than that of conventional Ti-MWW. It is believed that the application of the convenient treatment method could provide an effective strategy for designing high-performance titanosilicate catalysts.

Highly effective methylated Ti MCM-41 catalyst for cyclohexene oxidation

A series of Ti containing MCM-41 materials were synthesized with different Si/Ti molar ratios and tested for cyclohexene epoxidation reaction. TiMCM-41 with Si/Ti ratio 40 which gave maximum conversion and selectivity to epoxide was methylated with methyltriethoxysilane (MTES) in this reaction. Accordingly, four different methyl loading (5, 10, 15 and 20 mol % of MTES w.r.t. TEOS) TiMCM-41(Si/Ti 40) samples were prepared. The materials were characterized by different physical techniques such as PXRD, FT-IR spectroscopy, UV–vis DRS spectroscopy, N2 adsorption-desorption isotherm, SEM-EDX, TEM, TGA and ICP-OES. The catalysts were then tested for cyclohexene epoxidation reaction in the presence of H2O2 avoiding TBHP. The conversion and selectivity for cyclohexene obtained with 10MeTiM-1 (Si/Ti 40) were found to be the best not only among the catalysts investigated in the present work, but also among all the catalysts studied so far for the reaction.

Mesoporous tin oxide: An efficient catalyst with versatile applications in acid and oxidation catalysis

Mesoporous tin oxide was prepared by template assisted and template-free methods. As-prepared materials were calcined at various temperatures to generate different nature (Brønsted and Lewis), amount and strength of acidic sites. The physico-chemical properties of the catalysts were studied by XRD, N2 sorption, pyridine-FTIR, NH3-TPD, DRS UV-vis, TGA, SEM, TEM, 1H MAS and 119Sn MAS NMR analyses. The catalytic behavior of mesoporous tin oxide catalysts was evaluated for acetalization and ketalization of glycerol with benzaldehyde and acetone respectively under solvent free conditions. The catalytic performance of mesoporous tin oxide was compared with that of other conventional solid acid catalysts namely H-ZSM-5, H-mordenite, H-beta, Al-MCM-41, Al-SBA-15 and Al-TUD-1. The efficiency of mesoporous tin oxide was also tested for cyclohexene epoxidation reaction. The catalyst prepared by template assisted method showed excellent catalytic performance compared to other catalysts due the difference in nature and amount of acidic sites in the catalyst. Meso-SnO2-T-350 was stable and reusable catalyst for four cycles without any appreciable loss in activity, and therefore it offers a good catalyst for potentially wide applications.

Co-Condensation Assisted Preparation of MoVI Schiff Base Modified Mesoporous Silica Catalyst for Enhanced Epoxidation of Olefins

An organic–inorganic catalyst was prepared by the reaction of p-salicylidine aminobenzoic acid with mesoporous silica modified with 3-chloropropyl groups. The hydrolysis and co-condensation of tetraethylorthosilicate (TEOS) and 3-chloropropyltrimethoxysilane (CPTES) took place during the preparation process. MoO2(acac)2 was then introduced into the mesoporous silica functionalized with a Schiff base ligand. The structural properties of the prepared catalysts were investigated by a series of techniques, such as elemental analysis, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption curves, and thermogravimetric analysis (TGA). The results demonstrated that the MoVI Schiff base complex was successfully tethered on the silica support, and the hexagonally ordered mesoporous structure of the SBA-15-type silica was well retained after the anchoring reaction. The heterogeneous catalyst showed good catalytic activities in the liquid-phase epoxidation of olefins with t-BuOOH as the oxygen source in 1,2-dichloroethane solvent at 80°C. Several important factors, including oxidant-to-substrate ratio, solvent, and catalyst reusability, were investigated. Under the optimum reaction conditions, using this heterogeneous catalyst for the cyclohexene epoxidation reaction, a high conversion of 97.20 % and selectivity of >99 % was achieved after 4 h, while the catalytic activity nearly remained unchanged over four runs.

Synthesis, structural determination, theoretical studies and catalytic activity of Mn(II) complex of N-isonicotinyl phosphoric triamide ligand

A new N-isonicotinyl phosphoric triamide ligand with the formula 4-NC5H4C(O)NHP(O)(NC4H8)2 (L) was synthesized and characterized by 1H, 13C, 31P NMR and IR spectroscopies. The reaction of MnCl2·4H2O with L led to the formation of a new 3D system {MnL2Cl2}n·34CH3OH (C1). X-ray crystallographic data revealed that the ligand binds to the neighboring manganese ions through the nitrogen atom of pyridine (Npy) and the oxygen atom of phosphoryl (OP) in a bidentate manner. The Mn(II) centers showed a distorted cis(Npy, Npy) cis(OP, OP) cis(Cl, Cl) octahedral configuration. In order to compare the relative stability of C1 (with all-cis configuration) and its possible all-trans isomer, C′1, density functional theory (DFT) calculations were performed and the results showed the preference of C1 over C′1 from energy point of view. Quantum theory of atoms in molecules (QTAIM) analysis was applied to elucidate the nature of interactions, and the results suggested an ionic character (closed-shell interaction) for Mn–OP bond, and a partial covalent contribution for Mn–Npy interaction. Natural bond orbital (NBO) analysis was also used to calculate the charge distribution on atoms in the complex. The complex C1 showed efficient catalytic activity in the oxidation reaction of some alkenes to their corresponding epoxides. In addition, the effect of temperature and reaction time on the conversion and selectivity of cyclohexene epoxidation reaction in the presence of C1 as catalyst was investigated.

Catalytic Epoxidation of Cyclohexene with Tert-butylhydroperoxide Using an Immobilized Molybdenum Catalyst

This work describes the synthesis of molybdenum complexes immobilized on a silica support and their performance in the epoxidation reaction of cyclohexene using tert-butylhydroperoxide as the oxidizing agent. The catalyst synthesis included solubilization of variable amounts of bis-oxomolybdenum (VI) acetylacetonate precursor in different solvents such as tetrahydrofuran (THF), ethanol, THF/water and ethanol/water mixtures and contact with the silica support. Characterization techniques demonstrated that the nature of the incorporated molybdenum species depends markedly on the solvent employed. If the solvent employed is an ethanol:water mixture, physical adsorption of the Mo-species onto the support surface occurs; however, when THF is used as the solvent (THF catalyst series), molybdenum is grafted on the silica surface via chemical bonding with the surface hydroxyl groups of silica. Specifically, these latter catalysts show similar performance to that of the homogeneous catalyst, although long-term experiments showed deactivation by leaching of the active phase.

Selective Epoxidation of Cyclohexene Catalyzed by New Bidentate Schiff Base Dioxomolybdenum(VI) Complex Immobilized on Crosslinked Polystyrene Microspheres

A new immobilized bidentate Schiff base dioxomolybdenum(VI) complex was prepared with chloromethlated crosslinked polystyrene (CMCPS) microspheres as starting carrier via two stepwise polymer reactions with p-hydroxybenzaldehyde and glycine as reagents, respectively, as well as a coordination reaction with MoO2(acac)2, and the immobilized dioxomolybdenum(VI) complex abbreviated to CPS-[MoO2(ALGL)2] (ALGL refers to the bidentate Schiff base ligand, which comes form aldehyde [AL] group and glycine [GL]) was used in the epoxidation reaction of cyclohexene with tert-butyl hydroperoxide (TBHP) as oxidant. In the epoxidation reaction of cyclohexene, this heterogeneous dioxomolybdenum(VI) complex catalyst has high catalytic activity and excellent catalytic selectivity.

Catalytic Activity of Histidine-Metal Complexes in Oxidation Reactions

Studies were carried out to determine the activity of complexes of essential amino acid histidine with heavy metals in the oxidation of cyclohexene with tert-butylhydroperoxide in toluene at 80°C. All complexes were prepared by interaction of metal ions and histidine at room temperature in aqueous solutions. Only the complexes of Mo and W were obtained from acidic aqueous solution. These complexes were characterized by UV-vis, FT-IR, Mössbauer spectroscopy, and EPR analysis. The products of the oxidation reactions were identified by GC/MS analysis. The complexes of Mo and V showed the best activity in the epoxidation reaction of cyclohexene in comparison with other complexes, such as Ni, Mn, Zn, Co, Cu, Cr, Fe, and W. The probable structures of the complexes are propounded on the basis of the analyses carried out.

Synthesis of Expanded Titanosilicate MWW-Related Materials from a Pure Silica Precursor

Titanosilicate forms of expanded MWW-related material are synthesized starting from a pure silica precursor, ITQ-1. This procedure improves the current synthetic route of the expanded titanosilicate MWW material (Ti-YNU-1), which requires the use of a borosilicate MWW as precursor and, consequently, several postsynthetic acid treatments for removing boron atoms from the framework. The expanded Ti-MWW-related materials presented here show better activity than regular Ti-MWW in the selective epoxidation reaction of cyclohexene using H2O2 as oxidant.

Mechanistic insight into the cyclohexene epoxidation with VO(acac)2 and tert-butyl hydroperoxide

The epoxidation reaction of cyclohexene is investigated for the catalytic system vanadyl acetylacetonate (VO(acac)2) with tert-butyl hydroperoxide (TBHP) as oxidant with the aim to identify the most active species for epoxidation and to retrieve insight into the most plausible epoxidation mechanism. The reaction mixture is composed of various inactive and active complexes in which vanadium may either have oxidation state+IV or+V. Inactive species are activated with TBHP to form active complexes. After reaction with cyclohexene, each active species transforms back into an inactive complex that may be reactivated again. The reaction mixture is quite complex containing hydroxyl, acetyl acetonate, acetate, or a tert-butoxide anion as ligands, and thus, various ligand exchange reactions may occur among active and inactive complexes. Also, radical decomposition reactions allow transforming V+IV to V+V species. To obtain insight into the most abundant active complexes, each of previous transformation steps has been modeled through thermodynamic equilibrium steps. To unravel the nature of the most plausible epoxidation mechanism, first principle chemical kinetics calculations have been performed on all proposed epoxidation pathways. Our results allow to conclude that the concerted Sharpless mechanism is the preferred reaction mechanism and that alkylperoxo species V+IVO(L)(OOtBu) and V+VO(L1)(L2)(OOtBu) species are most abundant. At the onset of the catalytic cycle, vanadium+IV species may play an active role, but as the reaction proceeds, reaction mechanisms that involve vanadium+V species are preferred as the acetyl acetonate is readily oxidized. Additionally, an experimental IR and kinetic study has been performed to give a qualitative composition of the reaction mixture and to obtain experimental kinetic data for comparison with our theoretical values. The agreement between theory and experiment is satisfactory.

La Complex@Fe–PILM Offering Resilient Option for Efficient and Green Processing toward Epoxidation of Cyclohexene

An overview focused on the synthesis, structural features, and catalytic applications of lanthanum salen complex heterogenized in iron pillared montmorillonite is described here. In this approach the pillaring species was introduced in the interlayers of montmorillonite by a simple cation-exchange mechanism. The material on subsequent calcination resulted in the formation of iron pillared montmorillonite. Consequently, lanthanum salen complex was intercalated into the porous structure of iron pillared montmorillonite. The prima facie evidence of pillaring and complex anchorage inside the pillared clay was established by various spectroscopic and analytical characterization techniques. The heterogeneous catalyst was identified to promote the cyclohexene epoxidation reaction very efficiently with tert-butylhydroperoxide (TBHP) as the oxidant, affording the desired product with a yield up to 95%. Again the reusability of the catalyst and its stability were investigated from its postcatalytic XRD and FT-IR an...

Fabrication of VMn@mesoporous silica for epoxidation of cyclohexene

Vanadium-manganese containing mesoporous silica (VMnS) was prepared by an in situ grafting route by varying the wt% of vanadium and manganese. The materials were characterized by SXRD, BET-surface area, pore size distribution, SEM, EDAX-semiquantitative analysis, XPS, TPR, DRUV-vis, FTIR. The modification of silanol groups were evidenced from the characterization results. The activity of the catalysts was evaluated for cyclohexene epoxidation reaction. VMnS (2:2) showed highest conversion of 75% with selectivity 94%. Interestingly, only side product 2-cyclohexene-1-one (5%) was produced over the same catalyst.

A novel approach towards solvent-free epoxidation of cyclohexene by Ti(IV)–Schiff base complex-intercalated LDH using H 2O 2 as oxidant

A novel heterogeneous catalyst has been developed by immobilizing Ti(IV)–Schiff base complex in Zn–Al/LDH by an ion-exchange method. Powder X-ray diffraction, Fourier transform infrared spectroscopy, diffuse reflectance UV–Visible spectroscopy, N 2-adsorption and thermal studies confirm the successful intercalation of the Ti-complex within the LDH structure. The supported catalyst shows an excellent catalytic activity in cyclohexene epoxidation reaction. In this paper, we report an environmentally benign reaction pathway in a solvent-free condition, taking H 2O 2 as oxidant. As high as 95% conversion of cyclohexene took place at 70 °C in 6 h. The heterogeneous catalyst can be recovered easily and reused multiple times without significant loss in catalytic activity and selectivity, which is a better green alternative for practical applications.