Research on Chemical Intermediates最新文献

The synthesis of ethyl (hetero)arylidene cyanoacetates, valuable intermediates in organic chemistry, has been investigated using several commercially available and synthetic nitrogen-based organocatalysts. 4,4′-Trimethylenedipiperidine (TMDP) was chosen as an efficient organocatalyst regarding short reaction times, excellent yield with a conversion of 100%, and high selectivity. The pure products could be isolated and devoid of a costly workup. The residue could be directly reused for the next catalytic run. Encouragingly, TMDP exhibited chemical stability and high recyclability in five subsequent runs without a significant loss in catalytic activity. Scale-up experiments also demonstrate the current strategy’s promising industrial application. Mechanistic studies were conducted to provide insights into the reaction pathways and possible interaction/reaction between organocatalyst and each reactant through performing control experiments and studying FTIR in neat state and NMR spectra in aprotic and protic deuterated solvents. The developed metal-free and halogen-free catalytic strategy offers cost-effectiveness, low toxicity, and enhanced sustainability.

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The synthesis of UiO-66 and UiO-67 metal–organic frameworks (MOFs) with high crystallinity, large surface area, and enhanced porosity presents a significant challenge. This study aims to investigate the effect of modulator variation on the structural and textural properties of UiO-66(Zr) and UiO-67(Zr), and to assess its impact on their catalytic performance in the catalytic transfer hydrogenation (CTH) of α-angelica lactone (AnL) to γ-valerolactone (GVL). UiO-66(Zr) and UiO-67(Zr) were synthesized via solvothermal methods, with varying amounts of modulator introduced during the process. The synthesized materials were characterized using spectroscopy and microscopy techniques. X-ray diffraction (XRD) analysis confirmed the presence of characteristic peaks for both MOFs, while FTIR spectroscopy identified the formation of Zr-O bonds, as indicated by peak broadening at wavenumbers 743 and 591 cm⁻¹ for UiO-66, and 743 and 578 cm⁻¹ for UiO-67. Field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FESEM-EDX) revealed that higher modulator concentrations enhanced the clarity of the octahedral shape and increased particle size. Nitrogen physisorption analysis demonstrated improvements in surface area, pore volume, and pore diameter with modulator addition. Thermogravimetric analysis (TGA) indicated that higher modulator content resulted in reduced ZrO₂ residue. The CTH reaction was conducted using 10 wt% catalyst at 90 °C for 6 h under reflux condition. All synthesized materials exhibited catalytic activity, producing GVL from AnL. Notably, UiO-66(Zr) synthesized without a modulator showed the highest activity, achieving 67% AnL conversion and 60% selectivity toward GVL. Interestingly, higher crystallinity, surface area, and pore volume were found to decrease catalytic activity and selectivity, likely due to size selectivity in GVL formation and a reduction in active sites or defects following modulator addition. The reusability tests confirmed the formation of carbon coke, likely due to polymerization reactions initiated by Brönsted acid sites, which subsequently lowered both the yield and selectivity.

To examine the relationship between chemical structure modification and photovoltaic performance, we designed six metal-free organic molecules (M₂-M₇) of structure D-π₁-A-π₂-A based on the base molecule M₁ of structure D-π₁-π₂-A, introducing a new auxiliary acceptor (A) and varying the π₂-spacer at the same time, to study their performance in dye-sensitized solar cells. Using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods, several parameters were calculated and discussed, including LUMO and HOMO energy levels of the HOMO–LUMO energy gap, frontier molecular orbitals, absorption properties, nonlinear optical properties (NLO), light-harvesting efficiency (LHE), electron injection driving force (ΔG_inj), dye regeneration driving force (ΔG_reg), reorganization energy (λ_total), and vertical dipole moment (μ_normal) of the studied dyes (M₁–M₇). The results of the proposed dyes proved promising for use as sensitizers in the DSSC device due to their lower energy gap, red- and NIR-shifted absorption band, higher LHE and NLO properties, lower ΔG_reg and λ_total values, negative ΔG_inj value, and higher μ_normal value reflecting higher V_OC compared to the reference dye M₁. The results of these proposed dyes (M₂-M₇) will be considered favorable indicators for experimenters to synthesize effective dyes for use in the DSSC device.

Water Extract of Pomegranate Ash (WEPA) emerges as a highly effective green catalyst in the one-pot multicomponent synthesis of orthoaminocarbonitrile tetrahydronaphthalene and its derivatives. The catalyst's utility extends to the novel synthesis of orthoaminocarbonitrile methyltetrahydronaphthalene, achieved through a reaction involving 4-methylcyclohexanone, malononitrile and aromatic aldehydes. The protocol boasts pleasing features including an easy workup procedure, short reaction time, high yield of products (92–96%) and a developed synthesis pathway that circumvents purification processes like chromatography. This research highlights the promising potential of WEPA as a green catalyst in the synthesis of valuable orthoaminocarbonitrile methyltetrahydronaphthalene compounds. Our research provides valuable insights into the stability and reactivity profiles of the derivatives of orthoaminocarbonitrile methyltetrahydronaphthalene through computational studies. DFT studies show that the synthesized compounds exhibit good reactivity, as the band gap of all compounds lies in the range of 4.4 eV.

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Prins reaction of isoprenol with butanal provides important intermediate 4-methyl-2-propyltetrahydro-2H-pyran-4-ol, which can be esterified to 4-methyl-2-propyltetrahydro-2H-pyran-4-yl acetate. This desired fragrance with fruity and rose scent is known, e.g., as Clarycet®. Molybdenum-modified MCM-41 materials were obtained by a wet impregnation method using a water solution of ammonium molybdate. We prepared several materials with different MoO₃ loadings. These materials were thoroughly characterized (nitrogen physisorption, acidity—temperature-programmed desorption, elemental composition, etc.). The activity of prepared materials was tested in Prins reaction of isoprenol with butanal in batch arrangement. The influence of various reaction conditions (catalyst type, solvent, and water addition) was tested. We showed that modification of MCM-41 with MoO₃ led to a significant increase of catalytic activity (butanal conversion at 4 h of reaction: 7% for nonmodified MCM-41 compared to 93% for material 5 wt% of MoO₃-MCM-41). Water addition to the reaction mixture positively influenced the selectivity of the desired substituted tetrahydropyranol (selectivity > 70%). Mo-modified materials were also active in the esterification of 4-methyl-2-propyltetrahydro-2H-pyran-4-ol with acetanhydride to 4-methyl-2-propyltetrahydro-2H-pyran-4-yl acetate providing desired product after 5 h with 100% selectivity and total conversion. Reaction in the “one-pot” arrangement was also performed.

Glycerol Carbonate (GC) production via carbonylation of glycerol with CO₂ reaction takes attention to its properties of enabling both the utilization of biodiesel by-product glycerol and the use of major greenhouse gas CO₂. Herein, the synthesis of GC via glycerol carbonylation with CO₂ over a series of ZIF-8 on nickel-loaded Alumina Aerogel catalysts was examined for the first time in literature. ZIF-8 growth on nickel-impregnated Alumina aerogel was executed using an in situ method. Synthesized catalysts were analyzed using SEM–EDX, FT-IR, DRIFTS, XRD, and N₂ sorption techniques. The carbonylation reaction of glycerol was conducted in the presence of a co-reactant (propylene oxide) and solvent (methanol). The influence of reaction parameters (temperature, catalyst loading, glycerol/co-reactant molar ratio, co-reactant type, catalyst type, and reaction time) on the catalytic activity (glycerol conversion, GC selectivity and yield) of the catalysts were investigated. It obtained high glycerol conversion (73%) for AA-2Ni-5ZIF, yield (31%), and selectivity (77%) of GC for AA-5Ni-15ZIF under optimized reaction conditions (150 °C, 7 bar, 2 h, 6% catalyst loading and 0.5 glycerol/propylene oxide). Compared to the literature, this activity was found under lower CO₂ pressure and reaction time. Unique features of catalysts such as suitable acidity, high surface area, more than one active crystal, and the presence of propylene oxide as a co-reactant promoted the rise of glycerol conversion, GC selectivity, and yield.

An eco-benign, efficient, cost-effective, high energy-efficient method has been devised for synthesizing diamino-4-phenyl-3,5-dicyano-2-pyridone through a one-pot, three-component reaction. The technique involves the reaction of aryl aldehyde, malononitrile, and cyanoacetic acid hydrazide at 60 °C, utilizing water extract of incense stick ash as a catalyst and recyclable medium. Utilizing water extract as a solvent and catalyst reduces dependency on hazardous and harmful solvents, which are typically non-renewable and contribute to unfavorable emissions. The used incense stick ash was characterized by XRD and EDS analysis. The ash extract consists of metal oxides and carbonates which are basic and can act as catalysts. The reaction proceeds through the Knoevengel reaction, subsequent Michael addition and followed by intramolecular cyclization to furnish N-amino-2-pyridone in good to excellent yields. The structures of the synthesized compounds were confirmed based on IR, ¹H, and ¹³C NMR spectral data analysis.

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Catalytic converters are used to convert harmful gases such as carbon monoxide (CO), nitrogen oxides (NOₓ), and unburned hydrocarbons (HC) into less harmful or harmless gas emissions like carbon dioxide (CO₂), nitrogen (N₂), and water vapor (H₂O). In this study, supported catalysts for use of these CO and NO were developed by deposition of noble metals on cordierite (Cor) support with impregnation (IMP) in aqueous media. Effects of catalysts and washcoating for cordierite support were evaluated for carbon monoxide and nitrogen oxide activity in a batch reactor. They were characterized using XRD, BET, Raman, FTIR, and SEM–EDS. All catalysts were found to be effective in carbon monoxide conversion. The washcoating of catalyst support with cerium, lanthanum, zirconium, and yttrium changed the activity of the catalyst. The catalytic activity increased 20% with the washcoating. The coating enhanced catalytic activity by using cerium and zirconium oxides which improved thermal stability, while rare earth elements like lanthanum and yttrium helped stabilize the catalyst and optimize carbon monoxide conversion although some combinations had a negative impact on performance. It was observed that the C-Cor-Rh catalyst (99.96%) and C-Cor-Pd converted almost all (99.94%) harmful NO gas. The results showed that these catalysts had high efficiency for converting harmful NO_x gaseous to different components. This study shown that innovative, cost-effective and highly efficient catalytic converters can be obtained by shaping the quality and quantity of the precious metals to be dopped to the support material through effective washcoating modeling.

The silica and silica-alumina nanolayers were prepared on an individual titania nanoparticle surface using photocatalytically-induced reactions. The spectroscopic and kinetic analyses for the degradation of the organic dye molecules were discussed in order to elucidate the overall mechanism. The silica and silica-alumina nanolayer surface, more acidic than the titania, enhanced the adsorption of the cationic methylene blue (MB), while the silica nanolayer surface, much more acidic than silica-alumina and titania, suppressed the adsorption of the neutral or anionic fluorescein (FC). The photocatalytic degradation of MB mainly proceeded by the titania excitation, while it was slightly triggered by the MB excitation. The dye-sensitized degradation process, i.e., the electron transfer from the dye molecules to the titania, is negligible. On the other hand, the FC degradation proceeded by both the titania excitation and the FC excitation depending on the FC species adsorbed on the titania and silica surface. The main species are the dianion interacting with the surface on the titania and the neutral or anionic one on the silica. The silica suppressed the adsorption and degradation of the FC due to its acidity. The electron transfer from the adsorbed FC molecules to the titania promoted the dye-sensitized degradation. The silica nanolayer effectively functioned as an adsorbent and enhanced the photocatalytic degradation of MB. A higher density of photons effectively decomposed a higher amount of the MB adsorbed on the photocatalyst surface. The dye adsorption process plays an important role in the dye degradation during the photocatalytic reaction.