Research on Chemical Intermediates最新文献

Developing efficient and environmentally sustainable pathways is a fascinating focus within the field of green chemistry. In this study, a bimetallic Co-Mg metal–organic framework (Co-Mg MOF) was synthesized through solvothermal conditions using Co²⁺ and Mg²⁺ ions along with NH₂BDC (2-amino terephthalic acid) as a rigid ligand. Comprehensive characterization was performed using powder X-ray diffraction (PXRD), nitrogen adsorption–desorption isotherm (BET method), thermogravimetric analysis (TGA), elemental mapping, and inductively coupled plasma (ICP) techniques. The as-synthesized catalyst exhibited great catalytic performance in the Knoevenagel condensation of malononitrile and benzaldehyde, possibly due to its abundance of basic and acidic sites. Besides this, the bimetallic MOF catalyst demonstrated superior catalytic activity compared to its single-metal counterparts (Co-MOF and Mg MOF), this enhanced performance is likely due to the synergic effect of incorporating Mg²⁺ into the Co-MOF framework. With the optimization of reaction conditions, a significant yield of the final products (involving various aldehydes and malononitrile) was achieved at room temperature within a short duration. The as-synthesized catalyst represented good stability and recyclability through the reaction process even after the 4th run. The results showed that the as-synthesized bimetal Co-Mg MOF exhibited superior potential as a catalyst in the Knoevenagel condensation reaction, in the presence of green solvent (ethanol).

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An efficient and environmentally sustainable domino protocol has been presented for the synthesis of spirodihydropyridines with privileged heterocyclic substructures involving a three-component reaction of isatins, β-diketones and 1-naphthylamine using ethanol as a solvent and nanostructured Eu-doped ZnO as recyclable and reusable heterogeneous catalyst. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy were used to characterise the nanostructured catalyst. The doping of europium with ZnO NPs increased catalytic efficiency and provided excellent yields of the products. The present synthetic protocol is most likely the first to explain the synthesis of spirodihydropyridines spiroannulated with chromenoquinolines, pyrimidoquinolines, indenoquinolines and acridines. The synthetic protocol is expected to be extended to synthesise a library of the hybrid molecules of pharmaceutical and medicinal interest and drug discovery research incorporating privileged heterocyclic substructure. This protocol has special features such as operation simplicity, high atom economy, shorter reaction time (10–20 min), mild reaction conditions and excellent yield (80–94%). The present synthetic methodology is advantageous for commercial uses due to the recyclability and reusability of the catalyst.

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Herein we report an efficient ionic liquid-catalyzed Gewald reaction for the synthesis of 2-aminothiophenes from 2,5-dihydroxy-1,4-dithiane and substituted activated nitriles. Under the reaction conditions of [HOEmim]PF₆:H₂O at a ratio of 0.4:0.1, a series of 2-aminothiophenes were synthesized with moderate to good yields (55–98.1%). Electrostatic potential surface map elucidated the promoting effect of an optimal water content on the reaction dynamics. Moreover, the catalytic system exhibited excellent recyclability and reusability, maintaining its activity without significant loss even after ten cycles.

Effective and notable elimination of leaching of the metal nanoparticle from the catalyst during catalytic processes is still a big challenge for researchers in the design of heterogeneous catalysts. Metal–organic frameworks in both pristine and modified types with an excellent capacity for adsorption and stabilization of metallic active species have received special attention. In this study, Zn-MOF (TMU-16-NH₂) was selected and modified with urea to enhance amino groups on the surface, and the Zn-MOF-NH₂ was further reacted with glutaraldehyde to achieve support with various sites containing nitrogen and oxygen atoms named Zn-MOF-NH₂-glutaraldehyde. This adsorbent revealed an outstanding capacity in the adsorption and stabilization of palladium nanoparticles to fabricate a novel heterogeneous catalyst Zn-MOF-NH₂-glutaraldehyde@Pd for the Suzuki coupling reaction. High performance, great yield of products, reusability, easy work-up, clean profile of reaction, and short reaction times are some of the benefits of the Zn-MOF-NH₂-glutaraldehyde@Pd catalyst.

Liquid phase dehydration of sorbitol in a solvent-free environment is carried out to examine catalytic activities of sulfated tin oxides (STO) and STO/Hβ catalysts. The catalysts were prepared by wet impregnation method and characterized by XRD, FTIR, TEM, N₂ physisorption, NH₃-TPD. Prepared catalysts were examined at different temperatures and various catalysts loading. Under optimized reaction conditions (temperature −220 °C, reaction time −3 h), both STO and STO/Hβ catalysts demonstrated complete conversion of sorbitol, achieving isosorbide selectivity of 66% and 87%, respectively. This may be due to higher surface area and high Bronsted acid sites of catalysts. Catalyst reusability was checked for 4 cycles and it was found that conversion remains intact and only minor change in selectivity of isosorbide was observed.

This study presented the synthesis of cerium dioxide (CeO₂) nanoparticles utilizing carboxymethyl chitosan (CMC) to augment their biocompatibility with subsequent silver doping to refine their properties. The undoped CeO₂ nanoparticles were characterized as a cubic fluorite crystal structure with an average particle size of approximately 17.5 nm. The undoped CeO₂ nanoparticles preserved the cubic fluorite crystal structure and spherical morphology of the nanoparticles; however, it induced modifications in their physical properties, including a reduction in particle size and unit cell volume and an expansion of lattice spacing. Cytotoxicity assays revealed that undoped CeO₂ nanoparticles did not exhibit cytotoxic effects on HaCaT cells within the defined concentration range, indicating that CeO₂ nanoparticles synthesized with CMC significantly enhanced their biocompatibility. The silver-doped CeO₂ nanoparticles demonstrated enhanced antioxidant activity and an elevated sun protection factor (SPF) compared to their undoped counterparts. The enhancement of these properties highlights their potential applications in biomedicine and cosmetics.

An innovative and efficient catalytic system was successfully constructed, and the accurate synthesis of benzo[4,5]imidazo[1,2-a]pyridines was realized through the coupling reaction of aminopyridine and arylboronic acid in the presence of copper (II) acetate catalyst with 4-OH TEMPO as oxidant. The present methodology offers several advantages such as high yields, shorter reaction times, easy work-up process, and mild reaction conditions.

TiO₂/RuO₂/CuO was used as a ternary nanocatalytic system to develop novel pyrazole derivatives in one-pot, three-component reaction via Knoevenagel–Michael addition. These pyrazoles were synthesized under optimized green and conventional methods using key reactants including 2-hydroxy-1-naphthaldehyde, phenyl hydrazine, and various active methylene compounds such as 1,3-dimethyl barbituric acid, barbituric acid, thiobarbituric acid, Meldrum's acid and dimedone. Chemical structures were established using various spectroscopic methods (IR, ¹H NMR and ¹³C NMR). The density functional theory (DFT) computations were performed using Gaussian 09 and Gaussview 5 software, and used the B3LYP technique and the higher-order basis set 6-311G++ (d,p). The DFT analysis of compounds 4a-e provided valuable insights into their electronic properties and chemical reactivity with compound 4e exhibiting highly reactive characteristics. The analysis also provided insights into stability and chemical reactivity, electrophilicity index and electronegativity values. The molecular electrostatic potential helped to identify reactive sites and predicting chemical interactions. The molecular docking revealed promising interactions and binding affinities for inhibiting c-Src. The binding energies and hydrogen bond interactions that have been calculated show that these compounds might be able to become useful inhibitors. This comprehensive analysis not only sheds light on specific binding interactions contributing to inhibitory activity but also sets the stage for future research. The Molecular dynamic analysis reveals a protein with distinct regions of high flexibility and stability. This pattern suggests a complex structure with potential for dynamic functional processes.

Dynamic reconstruction of the catalyst under operating conditions is crucial for the rational design of a catalyst to improve the catalytic performance. Previous reviews mainly focused on in situ characterizations of the phenomenon, and this review emphasizes the relationship between the phenomenon and the catalytic performance. Specifically, this review subdivides the dynamic reconstruction of the metal-based catalyst into four main classes, including sintering/redispersion, surface segregation, reshaping, and composition evolution. The relationship is discussed between these changes and the catalytic performance, including catalytic conversion, product selectivity, and reaction mechanism. We believe that the dynamic reconstruction is derived from the redox reagent under thermal and pressure environments. The dynamic reconstruction affects the exposed area, specific crystal facet, element valence, and multi-metallic interaction of active species in a catalyst. These changes are firmly related to the catalytic performance. Finally, we put forward the challenge and potential solutions for further development of dynamic reconstruction and catalyst science.

The effectiveness, recyclability, and easy-to-use operation of the heterogeneous Fenton catalyst are of great importance in treating dye wastewater. Herein, we prepared a fiber-loaded heterogeneous Fenton catalyst with glass fiber as the carrier, and investigated the effectiveness and recyclability in degrading organic dye wastewater. It shows that the degradation process of methylene blue (MB), Congo red (CR), and crystal violet (CV) in the catalyst and H₂O₂ system conforms to a pseudo-first-order (PFO) kinetic equation, with the maximum degradation rates of 91.95%, 94.17%, and 96.03% within 100 min at 40 °C, respectively. The catalyst exhibits excellent recyclability, maintaining a degradation rate above 80% after 6 cycles for CR and 7 cycles for MB and CV. All results demonstrate that the catalyst is an excellent heterogeneous Fenton catalyst with high dye degradation efficiency, good recyclability, mild reaction condition, and easy-to-use operation, which holds promising great potential for application in dye wastewater treatment.