Research on Chemical Intermediates最新文献

Copper immobiolized onto the polyvinyl imidazole coated magnetic graphene oxide [MGO@PVimCu(I)] was synthesized and characterized by various analytical methods such as FT-IR, XRD, TGA, TEM, FESEM, VSM and ICP-OES. According to the FE-SEM and TEM results, the size of the snared nanoparticles in the polymer matrix was about 50–90 nm and the surface of the catalyst was rough. The loading percentage of copper onto the polyvinyl imidazole coated MGO was determined to be 17% using ICP-OES, which is far better than the many known metal-based heterogeneous catalysts. In the catalytic activity scrutiny, A³ coupling reaction for the preparation of propargylamines and coupling reaction of aryl halides with nucleophiles were aimed. In the presence of MGO@PVimCu(I), the corresponding products were gained in these reactions with moderate to excellent yields in aqueous medium (50–99%). This method demonstrates several considerable benefits including product yields, the use of various substrates, easy work-up, separation of catalyst by a simple external magnet, reusability of catalyst (at least four cycles), eco-friendliness, and avoidance of using any toxic solvent. The results of this study have shown that this catalyst can be a suitable candidate for other organic transformations.

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A theoretical investigation of the electrochemical reaction between β-nitrostyrene and benzaldehyde was conducted at the DFT M06-2X/def2-TZVP level of theory. The reaction mechanism was dissected into five proposed routes, via 3 pathways, concluding with 4 possible products (P1 to P4). To gain a comprehensive understanding, we explored these routes both in the gas phase and in solution using three solvents: dimethylformamide, methanol, and water. In the gas phase, the overall barriers of these five routes (the energy in parentheses refers to the relative G versus reactants in kcal/mol) are in this order: A2 (− 48.22) < A1 (21.29) < C1 (21.59) < B (29.81) < C2 (77.59). The ΔG for the formation of four products (the energy in parentheses refers to the relative G versus reactants in kcal/mol) are in this order: P2 (− 233.40) < P4 (− 82.13) < P3 (− 74.18) < P1 (− 46.97). Therefore, in the extra amount of both benzaldehyde and proton, P2 is the major product, in the extra amount of benzaldehyde and minimum amount of proton, P1 is preferred, and in the small amount of benzaldehyde and proton, P4 is preferred (only via C1 route). In the solvents, despite the gas phase data, path B and product P3 are a favorable path and products. Thermodynamically, the average relative G in three solvents for P3 is − 112.09 kcal/mol, for P2 is − 112.1, for P4 is − 118.46, and for P1 is − 60.25. Kinetically, the average relative G in three solvents for the transition states of P3 is − 8.25 kcal/mol, P2 is − 42.84, P4 is 34.16 via route C1 and 29.05 via route C2, and P1 is 95.81. Therefore, in the excess concentration of proton, P2 is the most favorable product by both kinetic and thermodynamic data and in low concentration of proton, P3 is the most favorable product.

The construction of heterostructures was considered to be an excellent strategy to achieve efficient charge separation and enhanced photocatalytic activity. Herein, the two-dimensional spherical In₂S₃ anchored onto the porous carbon nitride surface by a facile self-assembly process benefiting from the special structural design, and the composite material is endowed with a large specific surface area and more active sites. And the novel S-type heterojunction structure can not only greatly improve the problem of carrier recombination but also maintain a high redox potential, thus further enhancing the performance of photocatalysts. Results showed that the best total photocatalytic degradation and remarkable photocatalytic activity effect of CBZ reaches 98.3% after 120 min could be obtained at the g-C₃N₄/In₂S₃ under near room temperature and pressure and without using any sacrificial agents or promoters. The composite catalyst still exhibited excellent stability after five cycles. This work will provide the deep understanding of constructing interface engineering modulation, providing enlightenment for the design of high-performance photocatalysts.

Ketonization is an effective means of eliminating carboxylic acids from bio-oil and increasing the carbon chain. Oxygen vacancy defects in metal oxides affect the catalytic performance. However, few studies have investigated the specific effect of oxygen vacancy defects on carboxylic acid adsorption. In this work, the interaction between acetic acid and defect anatase TiO₂ (101) was analyzed using density functional theory (DFT). Surface oxygen vacancies are more difficult to form than subsurface, but acetic acid is more readily absorbed at the surface defects. The static point potential difference between surface Lewis acid and basic sites promotes the dissociation of acetic acid on both intact and defective surfaces, especially on the surface oxygen vacancies, which decreases the reaction energy barrier for water formation during ketonization. Additionally, surface oxygen vacancies convert the bidentate carboxylates formed on the perfect surface into more active monodentate carboxylates, which reduces the energy barrier for carbon–carbon coupling reactions in the ketonization. These results indicate that the surface oxygen vacancies can enhance the ketonization of acetic acid and demonstrate that the adsorption of macromolecular organics on catalysts is influenced by a combination of Lewis acidic strength, electrostatic site distribution, interfacial structure, and reactant active sites. Our results reveal in detail the effect of acetic acid adsorption on surface oxygen vacancies at the molecular level, which lays the foundation for further studies on the catalytic reaction mechanism as well as the regulation of catalysts.

Drug contamination is one of the most dangerous categories of impurities, which can be mitigated by photocatalysis reaction. Despite the unignorable advantage of nanophotocatalyst, their separation from batch reaction is challenging. Herein, a developed equipment is presented based on immobilizing a nanocatalyst onto the surface of a non-soluble polymeric substrate to degrade high amounts of chloramphenicol and amitriptyline under UV radiation. At first, polyvinyl alcohol plates were prepared through cross-linking by C₆H₉NaO₇ in the presence of C₅H₈O₂ and then characterized according to the water uptake amount and measuring water contact angle. The nanocatalyst was prepared by mixing two separate core–shell suspensions of Fe₃O₄@SiO₂ and WO₃@TiO₂; afterward, Fe₃O₄@SiO₂–WO₃@TiO₂ was sprayed onto the surface of the plates. The materials were characterized by X-ray diffraction spectroscopy, FTIR analysis, scanning electron microscopy, energy dispersive X-ray spectrometry, elemental mapping analysis, thermogravimetric analysis, Brunauer−Emmett−Teller and diffuse reflectance spectroscopy. The degradation recovery was optimized with respect to pH, UV radiation time and nanocatalyst amount. The adsorption efficiency, degradation efficiency, reusability, reproducibility, durability, effect of interference ions, adsorption isotherm, adsorption kinetic, photocatalytic kinetic and degradation mechanism were studied and explained. Analytical greenness metric approach is reported. Four different water samples were successfully employed as real samples.

The present study delineates the development of an optimized one-pot methodology for the synthesis of pharmacologically significant fused 1,2,3-triazole derivatives, assisted by the catalytic influence of triethylamine at ambient temperature. Noteworthy attributes of this protocol include excellent yields (up to 94%), ecological compatibility, and sustainability, rendering it advantageous from a synthetic standpoint. Green chemistry facets were integrated into the methodology, affirming its adherence to sustainable synthesis practices and highlighting its environmental friendliness. The characterization of the synthesized compounds was accomplished through comprehensive spectroscopic techniques, encompassing FT-IR, ¹H-NMR,¹³C-NMR, mass spectrometry, and elemental analysis. Furthermore, a quantum computational investigation was conducted employing density functional theory at the B3LYP/6-311G++(d,2p) level to elucidate chemical reactivity parameters. Remarkably, the HOMO–LUMO behavior was examined to ascertain the energy gap and molecular electrostatic potential of the synthesized compounds, thereby offering insights into their electronic structure and reactivity. In addition, a correlation between theoretical predictions and experimental observations were established, enhancing the credibility of the findings. Moreover, the optimized strategies for ¹H-NMR and ¹³C-NMR spectral data acquisition were devised, ensuring robust and reliable spectroscopic characterization of the synthesized compounds.

Some aryl E-imines were synthesized by nano-fly-ash H₃PO₄-catalyzed condensation of various aryl anilines and benzaldehydes under ultrasound irradiated greener solvent medium. In this condensation, the obtained yield was more than 75%. These E-imines were characterized by their physico-chemical data, microanalysis, and spectroscopic data. The characteristic spectral frequencies were employed for spectral quantitative structure–activity relationship study. The spectral QSAR study was performed with single and multi-regression analysis using Hammett σ, σ, σ_I, σ_R F R, and Swain–Lupton’s constants. From the outcome of the regression, the effect of substituents on the spectral frequencies was predicted. The molecular docking study of these imines was performed by the assessment of protein–ligand interaction study with a characteristic protein. The antimicrobial activities of these imines were studied using the Bauer–Kirby disk diffusion technique with various bacterial and fungal microbes. The in vitro antimalarial activity of these imines was measured using P. Falciparum Thai protein microbes.

In this study, we investigated the effectiveness of charge charge-enhanced dry impregnation (CEDI) method on a ceria-supported nickel-based catalyst (10Ni/CeO₂) used to produce synthesis (syngas) under biogas dry reforming conditions. The CEDI method was used to enhance the electrostatic adsorption of nickel precursor onto the ceria support during dry impregnation (DI), hence charge-enhanced dry impregnation. The other ceria-supported nickel-based catalyst (labelled 10Ni/CeO₂-DI) was prepared by the commonly used DI method and used as the reference catalyst. The catalysts were then tested for stability and catalytic performance (biogas conversion and syngas yield) under biogas reforming conditions using CatLab-QGA equipment supplied by Hidden Analytical. The characterisation studies: X-ray diffraction (XRD), N₂ adsorption/desorption, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), oxygen temperature programmed oxidation (O₂-TPO), temperature programmed reduction (TPR), and H₂-chemisorption were performed on the fresh and spent catalysts to gain insight into the influence of the CEDI method on dispersion, nanoparticles size of the active phase, metal-support interaction, bulk composition, and phase composition. The results showed that enhancing electrostatic attraction during the DI method produced 10Ni/CeO₂-CEDI with smaller nanoparticles (3.33 nm), improved nickel dispersion from 1.40 to 5.04% and improved metal-support interaction inferred from TPR values increased from 290 to 340 °C. These favourable physicochemical properties had a positive correlation with the improvement in the conversion of model biogas feed and the least coke formation.

In the current work, a new aliphatic tertiary poly(amic acid) with linear and cyclic spacers was synthesized via the catalyst-free process. The ring opening of ethylenediaminetetraacetic acid dianhydride (EDTADA) by piperazine, a bifunctional cyclic secondary diamine, was conducted in a polar solvent (DMF) in a nitrogen atmosphere for 3 h. The characterization was conducted by FTIR and NMR analysis. The morphology and elemental composition were investigated by field emission scanning electron microscopy and energy-dispersive X-ray (FESEM-EDX). As-synthesized aliphatic tertiary poly(amic acid) could be separated as a white powder with an O/N ratio of 0.93 and morphology of woven fiber. The white powder showed an average molecular weight (M̅w) of ∼12,000 and a polydispersity index (PDI) of 1.52 ± 0.05. In addition, the poly(amic acid) TGA/DTA analysis showed a high thermal stability with stepwise degradation with the onset of 346 °C. The poly(amic acid) DSC profile displayed a high glass transition at 124 °C. The Brunauer–Emmett–Teller (BET) surface area and pore volume were determined to be 146.05 m²/g and 0.78 cm³/g. The poly(amic acid) contains the mesopores and macropores based on its pore size distribution curve. Regarding an acidic pH and abundance of functional groups, as-prepared tertiary poly(amic acid) was employed as a heterogeneous catalyst for preparing 3,4,5-trisubstituted furan-2-ones in ethanol. A conversion of 100% and pure products could be isolated in good to excellent yields directly from ethanol. No remarkable loss of catalytic activity was observed in the recycling of the catalytic system even after the 5th recycling. A gram scale of model reaction gave an 82% yield of the respective product. Therefore, 3,4,5-trisubstituted furan-2-one derivatives could be prepared in the laboratory and gram scale by an energy-, cost-, and time-saving strategy with a halogen-free and metal-free heterogeneous catalyst.

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