Research on Chemical Intermediates最新文献

A new mixed ligands Cobalt complex of Schiff base and 2,2′-bipyridine was anchored onto the mesoporous MCM-41 to synthesize a highly efficient and reusable heterogeneous catalyst. The prepared heterogeneous catalyst was characterized by FT-IR, UV-DRS, PXRD, SEM-EDX, ICP-OES, HR-TEM, TGA, N₂ adsorption and desorption and ¹³C-CP-MAS-NMR. The Salen-Co-MCM-41-bipy complex has been found as a more promising catalyst for Knoevenagel condensation of aryl/alkyl malononitriles using different kind of aldehydes with malononitrile in EtOH/H₂O solvent mixture under room temperature with the yield upto 99%. The catalyst was performed well against a wide range of substrates, viz, the aldehydes of aryl, fused aryl, hetero and aliphatic compounds with a variety of substituents at various positions. Moreover, the effectiveness of our catalyst against large-scale reaction up to 2.5 g of substrate was also explained. The catalyst is recovered by simple filtration and reused up to five times without any loss in activity. Hot filtration test was explored the heterogeneous nature of the recovered catalyst. Previous reports were compared and discussed to spotlight the efficiency of our catalyst.

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Sulfated trishydroxyaminomethane has been found to be an efficient solid acid catalyst for the solvent-free synthesis of bisindolylmethanes. This innovative catalytic approach’s attractive features include its sustainability, ease of workup, economic viability, and biodegradability. The sulfonated trishydroxyaminomethane catalyst was assessed using infrared spectroscopy, scanning electron microscopy, wide-angle X-ray scattering analysis, and nuclear magnetic spectroscopy analysis. The results clearly show that sulfonation has been functionalized. The catalyst could be reused six times without exhibiting a discernible drop in activity. Furthermore, chromatographic separations may not be required to achieve the desired products with good yields.

Zinc oxide (ZnO) nanoparticles have been identified as a highly efficient and recyclable catalyst for the microwave-assisted synthesis of 1,8-dioxooctahydroxanthenes in an ethanol solvent medium. In this study, ZnO nanoparticles were synthesized via a green approach using Mirabilis Jalapa flower extract as a natural reducing agent, offering an eco-friendly and sustainable alternative to conventional chemical methods.The nanoparticles were thoroughly characterized using ultraviolet–visible (UV–vis) spectroscopy, Field-Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscope (TEM), Energy Dispersive X-ray analysis (EDX), Elemental Mapping, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), X-ray Photoelectron Spectroscopy (XPS) analyses and Fourier Transform Infrared Spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis. X-ray diffraction (XRD) results confirmed the formation of a crystalline hexagonal wurtzite structure. The catalyst demonstrated excellent recyclability, being easily recovered through simple filtration and reused for up to five consecutive cycles without significant loss of efficiency. This nanostructure-based heterogeneous catalytic protocol is not only sustainable and environmentally friendly but also economically advantageous due to the high recyclability of the catalyst.

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The synthesis of 2,4,5-substituted imidazoles has garnered significant attention due to the diverse biological activities exhibited by these compounds. In this study, we report a novel approach utilizing copper ferrite-coated silica–titania nanocomposites, CuFe₂O₄@SiO₂.TiO₂, as an efficient catalyst for the one-pot synthesis of 2,4,5-substituted imidazoles. The reaction protocol involves the condensation of aryl aldehydes, benzil, and an ammonia source (ammonium acetate) under mild conditions. The synthesized nanocomposite catalyst demonstrates impressively high catalytic activity and selectivity, achieving good yields of the desired imidazole derivatives. Comprehensive characterization of the nanocomposites using techniques such as FT-IR, XRD, SEM, and TEM confirmed the successful synthesis and morphology of the catalyst. The catalyst’s effectiveness highlighted its recyclability and stability over six reaction cycles, making it a promising candidate for green synthetic methodologies. The optimized reaction conditions achieved excellent yields within a short reaction time and showcased the potential of this nanocomposite in facilitating green chemistry practices. This work highlights that the versatility of CuFe₂O₄@SiO₂.TiO₂ nanocomposites in organic synthesis opens new avenues for developing efficient catalytic systems to prepare biologically significant heterocycles, instilling hope for a more sustainable future in the field of chemistry.

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In developing effective catalytic systems, understanding the interaction between reactant(s) and organocatalysts plays a crucial role in establishing the structure–activity relationship (SAR) in catalysis. This work investigated the interaction between imidazole, an organocatalyst, with the reactants in the Knoevenagel condensation of 2-chlorobenzaldehyde with malononitrile and ethyl cyanoacetate. Due to the solvent's impact on plausible interactions between reactants, organocatalysts, and intermediates, the study was conducted using FTIR and 1D NMR spectroscopic techniques. There was a correlation between the reduction of the acid methylene group intensity in ¹³C NMR spectra and the activity of acid methylene compounds. A reduction in α-carbon intensity of 75% and 23% for the malononitrile and ethyl cyanoacetate, respectively, was observed in the presence of one equivalent of imidazole. Moreover, the study introduced a greener and more sustainable solid-state procedure for the gram-scale preparation of 2-chlorobenzylidene malononitrile and 2-chlorobenzylidene cyanoacetic acid ethyl ester using a catalytic loading of imidazole, demonstrating the economic and practical aspects of the slurry mechanochemical process. The crystalline pure products could be isolated directly from an ethanol solution, and the residue containing imidazole was used in the next reactions without purification or activation after removing ethanol with a rotary evaporator.

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In this study, a mild and efficient solvent-free synthesis strategy was developed for the preparation of N-benzylidenebenzylamine via selective catalytic oxidation of benzylamine with oxygen over a composite MoO₃/SiO₂ catalyst. The result demonstrate that the 20%MoO₃/SiO₂ catalyst shows exceptional catalytic performance and stability. Even after five consecutive reaction cycles, the catalyst maintains a benzylamine conversion exceeding 97% and a N-benzylidenebenzylamine selectivity of 96%. Experiment and characterization results reveal that surface hydroxy groups of the MoO₃/SiO₂ play a critical role in the catalytic activation of benzylamine. Moreover, the existence of oxygen vacancy can facilitate the activation of oxygen. Finally, a plausible reaction pathway for the catalytic oxidation of benzylamine to N-benzylidenebenzylamine over MoO₃/SiO₂ is proposed. This study employs a cost-effective, simple, and highly active supported MoO₃/SiO₂ catalyst to selectively oxidize benzylamine into N-benzylidenebenzylamine in a solvent-free environment, demonstrating broad industrial application potential.

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A cost-effective and high photocatalytic degradation for tetracycline novel bismuth and hollow cerium oxide composite materials (Bi/h–CeO₂) photocatalyst was prepared. Hollow cerium oxide microspheres (h–CeO₂) were prepared using the traditional templating method, and the Bi/h–CeO₂ was prepared from h–CeO₂ and bismuth nitrate pentahydrate in different molar ratios by the hydrothermal process. Based on the material morphology characterization and the photocatalytic degradation performance of the sample, the results clearly indicated that the addition of nanostructured Bi significantly improved the photocatalytic property of h–CeO₂. Additionally, the 0.01Bi/h–CeO₂ photocatalyst exhibited maximum photocatalytic activity and the degradation efficiency can attain 90.2% after 30 min of irradiation. A potential mechanism has been suggested for the photocatalytic degradation of tetracycline (TC) using Bi/h–CeO₂ under visible light.

Tetracycline (TC) has the characteristics of widespread use and environmental persistence, and has become a widely residual high ecological risk pollutant. In this study, we developed a natural suspended sediment (SS)-based adsorption-catalysis bifunctional system, achieving peroxymonosulfate activation and used for efficient removal of TC. Under optimized reaction conditions (pH = 7.0, [peroxymonosulfate] = 0.4 mM, SS = 2.5 g/L, [TC]₀ = 50 mg/L), the TC removal efficiency reaches 83.9%. Adsorption analysis shows that TC adsorption by SS follows a pseudo-second-order kinetic model (R² > 0.99), with a maximum theoretical adsorption capacity of 237.51 mg/g. The adsorption process combines monolayer and multilayer mechanisms. X-ray photoelectron spectroscopy (XPS) analysis and electron paramagnetic resonance (EPR) detection confirm that Fe active sites in SS facilitate electron transfer pathways for peroxymonosulfate activation, with singlet oxygen (¹O₂) identified as the dominant reactive species responsible for TC degradation. Liquid chromatography-mass spectrometry (LC–MS) analysis elucidates three major TC degradation pathways: hydroxylation, demethylation, and demethyleneation, ultimately yielding low-toxicity or non-toxic small organic molecules and inorganic products. The SS/peroxymonosulfate system achieves a TC removal efficiency exceeding 80% across a pH range of 4–11 and demonstrates strong adaptability to TC concentrations ranging from 10 to 110 mg/L. Inorganic anions and natural organic matter (humic acid, HA) affect TC removal to varying degrees. This system effectively reduces the expression levels of antibiotic resistance genes (ARGs) in sediments by 12–17%, suggesting its suitability for the in situ remediation of antibiotic-contaminated water. Furthermore, it offers potential for the development of SS-based advanced oxidation processes (AOPs) for environmental applications.

In this study, porous MoS₂ nanoflowers (NFs) were synthesized via a facile hydrothermal approach and evaluated for their photocatalytic activity toward the degradation of methylene blue (MB) under simulated sunlight. The as-prepared MoS₂ NFs exhibit a hierarchical structure composed of ultrathin nanosheets with abundant surface area and active edge sites, facilitating efficient light absorption and charge separation. Photocatalytic experiments revealed a high degradation efficiency of 98.30% in the first cycle and excellent reusability, retaining 93.30% efficiency after three cycles. Radical scavenging tests identified superoxide radicals (O₂^·−) as the dominant reactive species involved in the degradation mechanism, supported by contributions from hydroxyl radicals (^·OH) and photogenerated holes (h⁺). The enhanced performance is attributed to the high crystallinity, large surface-to-volume ratio, and improved charge carrier dynamics enabled by the porous nanoflower architecture. These results highlight the potential of MoS₂ nanostructures as efficient and stable photocatalysts for practical wastewater treatment applications under solar irradiation.

⁵⁷Fe–N–C electrocatalysts were synthesized via ultrasonic treatment and electron beam (e-beam) irradiation, enabling rapid nanoparticle formation under mild conditions. Mössbauer spectroscopy was used to analyze the oxidation and spin states of Fe–N₄ species. The ⁵⁷Fe-labeled samples prepared using e-beam irradiation exhibited three Fe(II)–N₄ configurations: low-spin (D1), medium-spin (D2), and high-spin (D3), observed at 4.2 K. A higher proportion of low-spin Fe(II)–N₄ sites strongly correlated with improved oxygen reduction reaction (ORR) activity. Notably, e-beam irradiation promoted the selective formation of these catalytically active low-spin sites, offering a scalable and efficient synthesis strategy.