Chemical Papers最新文献

In this work, the potassium promoted Fe–Ce composite oxides supported on the monolithic three-dimensional (3D) macroporous nickel foam substrates (KFeCe@NF) were synthesized by sequential wetness impregnation method and used for catalytic soot combustion. The best catalytic performance was obtained over K(0.1)FeCe@NF catalyst under 10%H₂O/800ppmNO/20%O₂/N₂ atmosphere using a wet contact mode and the lowest T₁₀, T₅₀ and T₉₀ values could reduce to 274 ℃, 313 ℃ and 353 ℃, respectively. A detailed comparison of the structural properties for the samples before and after potassium loading was conducted by XRD, FESEM, EDS and XPS. The addition of K could lead to reduction of partial Fe₂O₃ to FeO and make the Fe₂O₃ nanosheets transform into agglomerated nanoparticles. Moreover, the enhanced catalytic performance of KFeCe@NF for soot combustion is main due to the abundant active oxygen species inspired by the strong interaction between potassium and transition metal oxides.

Improving the accessibility of bioactive compounds enriched ripen graviola fruit (Annona muricata) by the application of post-harvest processing technology would overcome their climatic barriers and be used as a folk medicine. Therefore, hot air drying technique was applied at various temperatures (40 °C, 50 °C and 60 °C) to evaluate the nutritional efficiency of the medicinal fruit. Drying characteristics of the ripen graviola fruit were determined, and predictive capability of artificial neural network and eight semiempirical models was evaluated. The Weibull model gave satisfactory results over the other models. Levenberg–Marquardt’s algorithm along with LOGSIGMIOD transfer function, predicted the moisture content and moisture ratio with better accuracy. Interestingly, the R² value of ANN was 0.9999, which was significantly more than that of the semiempirical model. Moisture diffusivity and mass transfer coefficient increased to 4.73 × 10⁻⁶m²/s and 2.386 × 10⁻⁶ m/s, respectively, as the temperature rose. Activation energy proved the conservative requirement of energy and was obtained as 24.659 kJ/mol. Radical scavenging activity (IC 50), polyphenol and flavonoid content were found to be maximum at 60 °C, and the values were 933.975 µg/ml, 7.088 mg GAE/g, 18.42 mg QE/g, respectively. Fruits dried at 60 °C showed lower moisture content (8% d.b), lower drying time, higher drying rate, better physico-chemical properties and sustainable colour value. Therefore, drying at 60 °C was recommended for commercialization in various nutraceutical applications and biotechnology aspects.

The development of effective techniques to produce functionalized indoles has garnered a lot of interest in synthetic organic chemistry. One of the most efficient processes for creating C–C bonds between indoles and electron-deficient substrates is the alkylation reaction. Since the advent of chiral transition metal-catalyzed alkylation reactions, Cu-catalyzed processes have gained attention for their ability to yield alkylated products. In this review, an overview of Cu-catalyzed alkylation reaction of indoles with various substrates, such as nitroalkenes, β,γ-unsaturated α-ketoesters, alkylidene malonates, N-sulfonyl aldimines, diazo compounds, alcohols, and other alkylating agents are discussed, covering the literature up to 2021.

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Indoles belong to a significant class of heterocycle due to its wide range of biological properties. As a result, indoles and its derivatives are of great interest to researchers. Transition metal-based Friedel–Crafts alkylation reaction for synthesizing alkylated indoles has gained more attention because they can afford the Friedel–Crafts adducts with high efficiency and selectivity. Among the various transition metals used, Cu has acquired considerable acceptance since it is less hazardous, inexpensive, eco-friendly, and has a huge spectrum of substrate scope. Cu-catalyzed alkylation reaction of indoles are highlighted in this review.

The electroreduction of CO₂ has been abundantly studied, but little attention has been given to the reaction occurring at the anode of this electrolyzer. Herein, we report one of the rare attempts to investigate the anode and potential reactions that could occur on this electrode during CO₂ electrolysis. The electrooxidation of several aqueous pollutants, sulfamethazine (SMT), carbamazepine (CMP), ketamine and acetaminophen (ACE) was investigated at the anode of a CO₂ electrolysis cell. Pulsed laser ablation in liquid (PLAL) was used to prepare the catalysts. PLAL is a versatile, environmentally safe technique used to create nanoparticles for electrocatalysis. Herein, bismuth nanoparticles were prepared as the CO₂ reduction catalyst, as previously reported. Nickel nanoparticles were used for both the oxygen evolution reaction (OER) and the oxidation of the aqueous pollutants. Transmission electron microscopy (TEM) of the nickel nanoparticles indicates the production of monodisperse nanoparticles, with a 7.8 ± 2.8 nm average diameter. After evaluating the stability of the targeted pollutants, we focused on sulfamethazine, carbamazepine and acetaminophen due to their stability in aqueous environment. Among the various anode catalysts tested, nickel nanoparticles were the most versatile in degrading these pollutants; thus, further measurements were taken with this catalyst. A brief optimization of the degradation conditions (pH and potential) was also done, showing most efficient degradation at pH = 9 and 1.4 V vs Ag/AgCl. Once completed, CO₂ reduction was coupled with the oxidation of a matrix of all three pollutants. The results show that the efficiency of the CO₂ reduction was mostly unaffected by the combined presence of the pollutants at the anode. Oxidation of the target pharmaceuticals was also comparable to previous tests, reaching 62% for CMP, 53% for SMT and 33% for ACE within 20 min.

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Capsaicin (CC), the dominant pungent compound in hot chilies, is widely used as a flavoring agent, preservative, and active compound in packaging film and functional foods. Capsicum chinense cv Bhut Jolokia is one of the richest sources of CC, yet scarcely studied. The present investigation aimed to optimize a clean and green method for extracting CC through supercritical fluid extraction (SFE) method. Low-grade, culled, and discarded fruits were used for the extraction, and process was optimized through central composite design of RSM. The optimized extraction condition, 68.31 °C/347.98 bars/102.50 min, resulted in maximum CC content (367.14 ± 1.12 mg/g) and oleoresin yield (7.23 ± 2.15%) in a shorter extraction time (< 2 h). Accelerated thermal stability study suggested first-order degradation kinetics of CC at temperatures from 80 to 140 °C. The activation energy (kJ/mol) of the reaction was 71.86, while temperature quotient (Q₁₀) for 80 to 100 °C, 100 to 120, and 120 to 140 were 0.0548, 0.0574, and 0.1456, respectively. Valorization of Bhut Jolokia for targeting an oleoresin with maximum CC opens a new window for its commercial exploitation in food industry. Furthermore, the study opens avenues for exploration of SFE-based extraction as a clean and sustainable method with reduced carbon footing.

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