Epoxidation Reaction Research Articles

Efficient Strategy for Characterization and Quantification of Polyunsaturated Lipids by Microwave-Assisted MMPP Epoxidation.

Lipids play integral roles in biological processes, with carbon-carbon double bonds (C═C) markedly influencing their structure and function. Precise characterization and quantification of unsaturated lipids are crucial for understanding lipid physiology and discovering disease biomarkers. However, using mass spectrometry for these purposes presents significant challenges. In this study, we developed a microwave-assisted magnesium monoperoxyphthalate hexahydrate (MMPP) epoxidation reaction, coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), to analyze unsaturated lipids. Microwave irradiation expedited the MMPP epoxidation, achieving complete derivatization in 10 min without byproducts. A diagnostic ion pair, displaying a 16 Da mass difference, effectively identified the location of the C═C bond in mass spectra. Microwave irradiation also significantly facilitated the epoxidation reaction of polyunsaturated lipids, achieving yields greater than 85% and yielding a complete epoxidation product. This simplifies chromatographic separation and aids in accurate quantification. Additionally, a purification process was implemented to remove excess derivatization reagents, significantly reducing mass spectrometry response suppression and enhancing analytical reproducibility. The method's effectiveness was validated by analyzing unsaturated lipids in rat plasma from a type I diabetes model. We quantified nine unsaturated lipids and characterized 42 fatty acids and glycerophospholipids. The results indicated that unsaturated fatty acids increased in diabetic plasma while unsaturated glycerophospholipids decreased. Furthermore, the relative abundances of Δ9/Δ11 isomer pairs also exhibited a close association with diabetes. In conclusion, microwave-assisted MMPP epoxidation coupled with LC-MS/MS provides an effective strategy for characterization and quantification of polyunsaturated lipids, offering deeper insight into the physiological impact of unsaturated lipids in related diseases.

Structure and Reactivity of Active Oxygen Species on Silver Surfaces for Ethylene Epoxidation.

The epoxidation of ethylene stands as one of the most important industrial catalytic reactions, and silver-based catalysts show superior activity and selectivity. Oxygen is activated on the surface of silver during the reaction and exerts a substantial impact on product selectivity. Notably, the oxygen species residing in the topmost atomic layers profoundly influence the reactivity of a catalyst. However, their characterization under in situ reaction conditions remains a huge challenge, and specific structures have not been identified yet. In this study, we employ in situ X-ray photoelectron spectroscopy and density functional theory calculations to determine the oxygen species formed at the topmost atomic layers of a silver foil and to assign them a structure. Three different groups of oxygen species activated on silver are identified: (i) surface lattice oxygen and two oxygen species originating from associatively adsorbed dioxygen and (ii) top and (iii) subsurface oxygen. Transient in situ photoelectron spectroscopy experiments are carried out to reveal the dynamic evolution and thus reactivity of the different oxygen species under ethylene epoxidation reaction environments. The top oxygen atom from the adsorbed associated dioxygen is the most active. Meanwhile, a frequency-selective data analysis method, developed to process time-resolved data, provides insights into the evolving trends of peak intensities for different oxygen species. The versatility of this method suggests its potential application in future time-resolved characterization studies.

Celecoxib Catalyzed the Coupling Reaction of Epoxide and CO2

Abstract: In this study, high yields of various cyclic carbonates are obtained by employing the drug celecoxib to promote the coupling reaction of CO2 and epoxide using tetrabutylammonium bromide. This strategy enables the synthesis of benzoic acid, phenylpropiolic acid, and 2, 4- quinazolinedione. In addition, the model reaction mechanism is proposed.

Catalytic Epoxidation of Carbonyl Compounds via Carbonyl Ylides: from Racemic to Enantioselective.

Transition metal-catalyzed epoxidation of carbonyl compounds through carbonyl ylides represents a highly effective method for synthesizing a diverse range of valuable epoxides. This review offers an in-depth overview of the latest developments in inter- and intramolecular epoxidation reactions involving metal carbenes and carbonyl compounds, encompassing both racemic to enantioselective transformations. These catalytic epoxidations are reviewed by highlighting their product selectivity, diversity and applicability, and the related mechanistic rationale is showcased where possible.

Organocatalytic Dearomative Spirocyclization Reaction of Enone-Tethered α-and β-Naphthols and Dearomatization Reaction of In Situ Generated Nitro-Olefin-Tethered α-Naphthols.

Herein, we report a catalytic dearomative spirocyclization reaction of new substrates having aryl/alkyl enone tethered α- and β-naphthols and a dearomatization reaction of in situ generated nitro-olefin-tethered α-naphthols. The spirocarbocycles were obtained in moderate to good yields with high diastereoselectivities. A preliminary catalytic asymmetric variant was reported. A few applications such as hydrogenations and epoxidation reaction have also been demonstrated. Theoretical study has also been performed to understand high diastereoselectivity in the triethylamine catalyzed spirocyclization reaction.

Functionally enhanced polyether-bridged amidopyridinium dicationic ionic liquids for highly efficient and sustainable fixation of CO2 to cyclic carbonates

Task-specific ionic liquids integrated with multi-active sites display promising potential for use in the cycloaddition reaction of CO2 and epoxides. Utilizing the functional enhancement strategy, we successfully synthesized a novel range of polyether-bridged amidopyridinium dicationic ionic liquids (PE-PyDILs) via efficient bisamidation and biquaternization reactions. Under relatively mild reaction conditions, PE-PyDILs can catalyze the coupling of CO2 with various epoxides to produce cyclic carbonates in quantitative yields, demonstrating an enhanced effectiveness and a longer service life compared to previous DILs. At a very low loading of 0.01 mol%, the TON value is as high as 7700. The excellent catalytic performance can be attributed to the intramolecular cooperative activation of epoxides with two amidopyridinium cations bridged by polyether, as supported by the spectroscopic analysis and kinetic studies. This mechanism led to a reduction in activation energy and improved the efficiency of the cycloaddition reaction.

Hydroxyl-functionalized ionic liquid-modified covalent organic frameworks for efficient CO2 cycloaddition conversion

Converting CO2 into high-value chemicals is an essential way to mitigate greenhouse impact and realize sustainable utilization of resources. In this work, the COF materials named X-QCOF (X = OH, OCH3) were synthesized by a three-component Povarov reaction, followed by chemical grafting of hydroxyl‑functionalized ionic liquid into the COFs neutral backbone via quaternization to obtain the hybrid materials IL-X-QCOF (X = OH, OCH3). The resultant IL-X-QCOF can efficiently catalyze the cycloaddition reaction of CO2 and epoxides in the absence of metals, additives and solvents. Among them, IL-OH-QCOF exhibits a yield of 97.2% of cyclochloroallyl carbonate with a high turnover frequency (TOF) value of 217.7. The inherent high specific surface area of the COF-based materials promotes mass transfer efficiency, and meanwhile the abundant hydroxyl groups and bromine anions occurring in the backbone create excellent catalytic effect. Attributed to the chemical grafting approach, the product yield keeps over 90% when IL-OH-QCOF is reused for 6 cycles.

Efficient formation of propylene oxide under low hydrogen concentration in propylene epoxidation over Au nanoparticles supported on V-doped TS-1

The direct epoxidation of propylene to propylene oxide (PO) represents a unique feature of gold nanoparticle catalysts. Different amounts of vanadium were introduced into TS-1 using a hydrothermal method to give V-TS-1, and the effect of various vanadium loadings on the catalytic performance of Au/V-TS-1 was investigated in the epoxidation of propylene under different reaction conditions. The obtained characterization results indicate that the molecular sieve pore structure and crystalline phase structure of TS-1 were maintained after vanadium incorporation, and vanadium was incorporated into the molecular sieve framework. The introduction of an appropriate amount of vanadium resulted in the homogeneous dispersion of gold particles with a small average particle size, which facilitated the epoxidation reaction. When V was introduced into TS-1, the propylene conversion decreased under the condition of 10 % H2 concentration (C3H6/H2 = 1/1) in the reaction atmosphere, but the PO selectivity was maintained. Interestingly, when the H2 concentration in the reaction atmosphere was lowered to 2 % (C3H6/H2 = 3/1), the propylene conversion in Au/TS-1 was significantly decreased compared to 10 % H2 concentration condition, while in Au/V-TS-1, the propylene conversion was maintained in 2 % H2 concentration condition compared to 10 % H2. Au/V-TS-1 also maintained its selectivity for PO even when the H2 concentration was lowered. Therefore, under low hydrogen concentration conditions, the PO formation rate of Au/V-TS-1 was much higher than that of Au/TS-1. More, the same trend was observed when Mo was added in place of V. Our strategy will guide the design of future catalysts as a way to utilize hydrogen more effectively while maintaining PO productivity.

Synthesis of titanium silicalite-1 supported zinc catalysts for efficient and clean epoxidation of 1-hexene and methyl oleate

To improve the catalytic epoxidation activity of conventional TS-1 zeolite under acid-free conditions, a series of TS-1-supported zinc (xZn/TS-1) catalysts were prepared and evaluated in the epoxidation of 1-hexene and methyl oleate (MO) with H2O2 oxidant. The microstructure of xZn/TS-1 was investigated using various characterization techniques, and the results showed that the introduction of Zn species was not only well dispersed on the surface of TS-1 but also did not disrupt the crystal structure of TS-1 and tetrahedral framework titanium. Furthermore, the Ti-O-Zn structure can be formed between Zn and Ti species through O-atomic coordination, which improves the vulnerability of the Ti-O bond to attack the H2O2 molecule, and ultimately facilitates the epoxidation reaction between 1-hexene and MO. In addition, the 2% Zn/TS-1 catalysts showed optimal conversions of 45.7 % and 75.41 % for 1-hexene and MO, respectively, and exhibited good catalytic stability and regeneration during the epoxidation process.

A Syringa pinnatifolia genome assembly reveals the zerumbone biosynthesis machinery with a cytochrome P450-catalysed epoxidation reaction in eudicots.

A Syringa pinnatifolia genome assembly reveals the zerumbone biosynthesis machinery with a cytochrome P450-catalysed epoxidation reaction in eudicots.

High-resolution 3D printable inks based on functional polymeric ionic liquids for applications in carbon dioxide valorization

This study investigates the use of epoxy-functionalized acrylate-based 3D printable ink for creating high-resolution functionalized devices, exploring the possibility to further functionalize those for chemical engineering applications. In fact, the control of the epoxy-functionalized surface enables the formation of active surfaces, and this study employs supported Ionic Liquids with catalytic properties as a proof of concept. Ionic liquids (ILs) and polymeric derivatives represent a promising path to generate multifunctional complex 3D structures, playing advanced roles in multiple applications. The fine-tuning of the functionalization methodology and formulation enhances the resolution of acrylate-based resins, allowing the production of highly detailed structures that can significantly boost catalytic efficiency. Through a comparison with commercial resins, the developed formulation demonstrates superior resolution capabilities, positioning it as an effective alternative for use in vat photopolymerization technologies. Additionally, controlling the level of functionalization and accessibility of the ILs' active sites through the control of the surface area of the reactor has led to improved process performance in terms of yield and space-time yield (STY) in the CO2 cycloaddition to epoxide reaction.

Origin of Chemoselectivity of Halohydrin Dehalogenase-Catalyzed Epoxide Ring-Opening Reactions.

By performing molecular dynamics (MD), quantum mechanical/molecular mechanical (QM/MM) calculations, and QM cluster calculations, the origin of chemoselectivity of halohydrin dehalogenase (HHDH)-catalyzed ring-opening reactions of epoxide with the nucleophilic reagent NO2- has been explored. Four possible chemoselective pathways were considered, and the computed results indicate that the pathway associated with the nucleophilic attack on the Cα position of epoxide by NO2- is most energetically favorable and has an energy barrier of 12.9 kcal/mol, which is close to 14.1 kcal/mol derived from experimental kinetic data. A hydrogen bonding network formed by residues Ser140, Tyr153, and Arg157 can strengthen the electrophilicity of the active site of the epoxide substrate to affect chemoselectivity. To predict the energy barrier trends of the chemoselective transition states, multiple analyses including distortion analysis and electrophilic Parr function (Pk+) analysis were carried out with or without an enzyme environment. The obtained insights should be valuable for the rational design of enzyme-catalyzed and biomimetic organocatalytic epoxide ring-opening reactions with special chemoselectivity.

A Review of Chemical Modification of Vegetable Oils and Their Applications

In order to cope with the shortage of non-renewable energy and the increasingly environmental pollution, sustainable vegetable oils, as competitive alternatives, have widely been held in the good graces of the researchers. Vegetable oils are suitable for a wide range of applications such as biofuels and biodiesel. However, the development of vegetable oils is limited due to the characteristics of unsatisfactory oxidation stability and poor cold-flow properties. Chemical modification is considered as an effective solution to enhance the performance. The research progress of the chemical modification methods and applications of vegetable oils in recent years are summarized in this review. Reducing the content of carbon–carbon double bonds and increasing the degree of saturation are the keys to improve the physicochemical properties of vegetable oils. The prospects for the development direction and challenges of vegetable oils are proposed. Future research may focus on the use of multifunctional catalysts to optimize reaction conditions or to introduce active groups with lubricating properties in epoxidation reactions and explore the combination of chemical and auxiliary methods.

Unusual Rearrangements in Cyclohex-3-ene-1-carboxamide Derivatives: Pathway to Bicyclic Lactones.

The synthesis of new bicyclic lactone derivatives was carried out starting from 2-methyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione. 6-(Hydroxymethyl)-N-methyl/phenylcyclohex-3-ene-1-carboxamide derivatives were obtained from the reduction of tetrahydro-1H-isoindole-1,3(2H)-diones with NaBH4. Bromination and epoxidation reactions of both compounds were examined, and the structures of the resulting products were determined by spectroscopic methods. Substituted bicyclic lactone compounds, which are interesting rearrangement products in both bromination and epoxidation reactions, were obtained. In particular, hydroxymethyl (-CH2OH) and amide (-CONHR) groups attached to the cyclohexene ring in the bromination and epoxidation reactions were found to be effective in product formation. As a result, a new and applicable method was developed for the synthesis of bicyclic lactone derivatives.

Facile synthesis of Al-g-C3N4/Bi2S3 with enhanced for CO2 cycloaddition reaction performance

In this paper, a high specific surface area lamellar heterogeneous composite catalyst (MCN) was synthesized for the cycloaddition reaction of CO2 and epoxides. MCN is doped aluminum with high catalytic activity in Bi2S3 and g-C3N4 with photocatalytic activity, and it was prepared by a facile one-step calcination method. This catalyst achieved 88 % and 97 % conversion and selectivity for the cycloaddition reaction of epichlorohydrin and CO2 with no change in yield after five cycles. In addition, the two compositions of Bi2S3 and g-C3N4 in MCN resulted in enhanced light absorption of the catalyst, thus providing some photothermal performance. This paper provides an idea for the design of bifunctional catalysts with Lewis acid-base.

Investigating the Mukaiyama-type epoxidation reaction of alkenes with Cr(III) salophen catalysts: A confrontation between experiments and DFT calculations

This study aimed at the complete elucidation of the mechanism of the Mukaiyama-type alkene epoxidation reaction using the [(salophen)CrIIICl] precatalyst, by combining spectroscopic (UV–visible and EPR) studies, catalytic reactivity and quantum chemical modeling. These studies performed in parallel allowed us to propose a detailed reaction scheme, in which two consecutive active species incorporating both {salophen(CrV = O)} moieties were formed in situ, resulting in two distinct catalytic regimes.

Highly efficient anionic ring-opening reactions of epoxide triggered by phosphide

Highly efficient anionic ring-opening reactions of epoxide triggered by phosphide

Multi-path asymmetric reactions of racemic epoxides mediated by an engineered Escherichia coli overexpressing SfEH2, a newfound epoxide hydrolase from Streptomyces fradiae SF-2

To enrich ‘epoxide hydrolase (EH) tool cabinet’ for preparing enantiopure epoxides and 1,2-diols, a novel microbial EH, SfEH2, was identified from Streptomyces fradiae SF-2. Bioinformatics analysis indicated that SfEH2 has typical structural characteristics of α/β-hydrolase fold superfamily. Its coding gene, sfeh2, was then codon-optimized and amplified. A recombinant (re) SfEH2-expressing E. coli BL21(DE3) strain (E. coli/sfeh2) was constructed through DNA manipulations. Substrate spectrum assay including fifteen common racemic (rac-) epoxides by E. coli/sfeh2 showed that reSfEH2 displayed the highest and best complementary regioselectivities (regioselectivity coefficients, αR = 89.7% and βS = 91.4%) towards rac-14a, as well as the highest enantioselectivity (enantiomeric ratio, E = 15.3) in S-type towards rac-15a. Molecular docking simulation revealed that SfEH2 preferentially attacked Cα of (R)-14a and Cβ of (S)-14a geometrically. In kinetic parameter analysis, the KmR (5.74 mM) of purified reSfEH2 for (R)-15a was 1.76-fold lower than KmS (10.09 mM) for (S)-15a. At last, using 50 mg dry cell weight/mL E. coli/sfeh2, the scale-up enantioconvergent hydrolysis of 100 mM rac-14a at 30 °C for 6.0 h afforded (S)-14b with 80.9% eep and 90.1% yield, while the kinetic resolution of 150 mM rac-15a retained (S)-15a with >99.0% ees and 42.2% yield.

Facile encapsulation of a cobalt complex inside the micropores of ZIF-8 through the bottle around the ship method: A novel heterogeneous catalyst for epoxidation of alkenes

A novel and stable heterogeneous catalyst for alkene epoxidation reaction, named as CoDMG@ZIF-8, has been synthesized by facile encapsulation of Co(III) complex i.e. [Co(DMGH)(DMGH2)Cl2] (abbreviated as CoDMG, DMGH2 denotes for dimethylglyoxime and DMGH denotes for dimethylglyoxime mono anion) inside the ZIF-8 micropores via a solvothermal process. Based on the results of fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) technique and field emission scanning electron microscopy (FE-SEM), it was observed that the catalyst has maintained the structure, crystallinity and morphology of the parent ZIF-8 as well. Furthermore, CHN, DRS (diffuse reflectance spectra), energy dispersive X-ray (EDX), induced coupled plasma (ICP-OES), thermal gravimetric (TGA) and nitrogen adsorption-desorption (BET method) analyses have confirmed the encapsulation of the CoDMG complex. The epoxidation reaction was performed using tert‑butyl hydroperoxide (TBHP) in CH3CN solvent in the presence of catalyst. By optimizing the reaction parameters, a total conversion of 96 % with 82 % selectivity towards the epoxide product, was achieved. It was found that both CoDMG complex and ZIF-8 exhibited lower efficiency individually, while the encapsulation of this complex inside the ZIF-8 micropores has resulted to superior activity. Finally, the epoxidation of various alkenes such as cyclohexene, 2-norbornene, α-pinene, styrene and 1-hexene under the optimized reaction condition, have been studied and the catalytic mechanism was also proposed.

Synthesis and photoinitiated cationic polymerization of epoxy monomers derived from oleic acid comprising one to three epoxy groups

A series of bio-based epoxy compounds based on oleic acid combined with aliphatic or aromatic structures were studied regarding selected properties such as melting behavior and viscosity as well as their reactivity in a photoinitiated cationic polymerization. The new epoxy compounds derived from oleic acid and either eugenol or isoeugenol, epoxidized triolein, and an epoxy compound derived from oleic acid and popane diol-1,3 contain 100 % renewable carbon. Atom economy differs not only for the esterification and epoxidation reaction, also selection of hydrogen peroxide or m-chloroperbenzoic acid for the epoxidation significantly influences the atom economy of this reaction step. Variation of the chemical structure of the bio-based epoxy compounds derived from oleic acid and either an aliphatic alcohol or a phenolic compound results in differences in both melting behavior and viscosity of the epoxy monomers that is important for the photoinitiated cationic polymerization. Kinetic investigation of the photoinitiated cationic polymerization of the bio-based epoxy compounds using photo-DSC shows significant differences in the polymerization rate and conversion as a function of the irradiation time for the epoxy monomers. RT-FTIR spectroscopy gives additional information about the polymerization kinetics for epoxy monomers that are liquid at room temperature. The glass transition temperature of the photopolymers analyzed by DSC is mostly below room temperature that is attributed to the high content of flexible structures containing in the polymers. Additional investigation of the soluble photopolymers by GPC resulted in a molecular weight corresponding to the oligomer region and a dispersity higher than one. The bio-based epoxy monomers comprising two or three epoxy groups may be interesting for application, e. g. in coatings or adhesives, because photoinitiated polymerization results in crosslinking. Epoxy compounds containing only one epoxy group may be useful for viscosity reduction of the photopolymerizing mixtures because of their lower viscosity compared to the epoxy monomers comprising more than one epoxy group.