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Developing efficient electrocatalysts for acidic electrosynthesis of hydrogen peroxide (H2O2) holds considerable significance, while the selectivity and stability of most materials are compromised under acidic conditions. Herein, we demonstrate that constructing amorphous platinum–selenium (Pt–Se) shells on crystalline Pt cores can manipulate the oxygen reduction reaction (ORR) pathway to efficiently catalyze the electrosynthesis of H2O2 in acids. The Se2‒Pt nanoparticles, with optimized shell thickness, exhibit over 95% selectivity for H2O2 production, while suppressing its decomposition. In flow cell reactor, Se2‒Pt nanoparticles maintain current density of 250 mA cm−2 for 400 h, yielding a H2O2 concentration of 113.2 g L−1 with productivity of 4160.3 mmol gcat−1 h−1 for effective organic dye degradation. The constructed amorphous Pt–Se shell leads to desirable O2 adsorption mode for increased selectivity and induces strain for optimized OOH* binding, accelerating the reaction kinetics. This selenization approach is generalizable to other noble metals for tuning 2e‒ ORR pathway. Developing efficient catalysts for acidic electrosynthesis of H2O2 is desirable, while most materials are compromised in acidic conditions. Here, the authors report that constructing amorphous Pt–Se shells on crystalline Pt cores can regulate the reaction pathway to efficiently produce H2O2 in acid. [ABSTRACT FROM AUTHOR]

In this study, we employed ab initio methods to investigate the 4π-photocyclization process of substituted α-tropones. Our findings suggest that the initial stages of this reaction occur from low-energy excited states such as S2 and S3, as the barriers in higher-energy excited states are prohibitively high. Additionally, we observed that the presence of acid catalysts or substitution of tropones with electron-donating groups reduces the energy barriers. Regarding the formation of bicyclo[3.2.0]hepta-3,6-dien-2-one derivatives, both T1/S0 and S1/S0 crossings were identified as plausible pathways for this deactivation process. Specifically, electron-donating groups on the tropones promote degeneracy between S1 and S0 states during the return to the ground state. Moreover, T1/S0 crossing systems were consistently observed across all investigated scenarios. [ABSTRACT FROM AUTHOR]

Nano-assemblies such as surfactant micelles and vesicles are widely used in drug carriers, bioreactors, and gene delivery, but can also be used as catalytic systems for chemical transformations. In the current study, we introduce nano-assemblies formed by a novel sulfonate-based amphiphilic catalyst, designated Cat-2, which are responsive to acid catalyst (HBF4) and metal catalyst (Fe(BF4)2). When the amphiphilic assemblies of Cat-2 were applied for dehydrative aminations of allylic or benzylic alcohols, we obtained the desired sulfonamide or carboxamide products with reasonable to good yields (58–92%). This methodology was also applied for gram-scale synthesis of the FDA-approved drug naftifine. Cat-2 formed small micelles (∼20 nm) in water, which were transformed into large nano-assemblies (∼550 nm) upon the addition of HBF4 and Fe(BF4)2. This morphological change mainly originates from the coordination of the sulfonate group to Fe2+. The resulting Cat-2-Fe2+ assemblies contain amide groups at the hydrophilic–hydrophobic interfaces, which act as mediators for an effective proton transfer from HBF4 in a bulk solution to the alcoholic substrate in the assembly interior. As a result, the protonated alcoholic substrate undergoes dehydration to initiate a catalytic cycle for the dehydrative amination reaction. The present methodology is favorable due to its facile and green setup, cost effectiveness, and use of easily accessible and non-toxic catalysts. In addition, the current study provides insight into the design of nano-assemblies for catalyzing organic transformations. [ABSTRACT FROM AUTHOR]

The one‐carbon degradation  of aliphatic carboxylic acids has been studied using a H2IrCl6‐Ru(CO)4I2 bimetallic catalyst. Alkanes, RH, have been obtained from the corresponding RCOOH in good to near quantitative yields via a process that is thought to involve (i) a decarbonylation process that involves the formation of alkenes along with CO and H2O, (ii) a water–gas shift (WGS) reaction to give H2 and CO2, and (iii) the hydrogenation of the resulting alkenes. [ABSTRACT FROM AUTHOR]

A new protocol for the synthesis of 2‐amino‐substituted 1,3,4‐oxadiazoles and 1,3,4‐thiadiazoles, were developed using semicarbazide or thiosemicarbazide along with the various aldehydes, followed by C−X (X=O, S) bond formation using ascorbic acid as a catalyst. This rapid, efficient, accessible, and robust/scalable sequential synthesis works with aromatic, aliphatic, and cinnamic aldehydes to provide a wide range of diazole derivatives with a 2‐amino substituent without the use of any transition metals. The synthesised molecules were characterised by 1H and 13C NMR analysis. [ABSTRACT FROM AUTHOR]

This work focuses on the rapid synthesis of Schiff bases with green protocols, where P2CA (Pyridine‐2‐carboxylic acid) is utilized as a catalyst. The condensation reaction of aldehydes and anilines, facilitated by P2CA, resulted in the production of Schiff bases in good to excellent yield within a remarkably short time of up to 15 min. The electronic effect of the various substituents on aldehyde and aniline, in combination with the catalytic effect of P2CA, accelerated the reactions under mild conditions. The reusability of the catalyst was thoroughly examined, and the catalyst was characterized over every cycle. Importantly, this approach is not only green and sustainable, but also cost‐effective, harmless, and environmentally friendly, thanks to the affordability and benign nature of P2CA. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis and characterization of novel thiosemicarbazone derivatives with potential antibacterial activity. Through a systematic two‐step synthesis process, involving the preparation of substitute aldehydes (A1–A6) followed by the formation of thiosemicarbazone derivatives (S1–S6), novel compounds (S1, S2) were successfully obtained. The structures of the synthesized compounds were thoroughly characterized using FT‐IR, 1H‐NMR, 13C‐NMR, LC/MS, UV‐Vis, and SEM‐EDX. The results highlight the significance of sulfuric acid as a catalyst in the synthesis of pyrazole‐thiosemicarbazide derivatives (S1, S2), demonstrating its superior efficiency compared to acetic acid. The compounds exhibited varying degrees of antibacterial activity against E. coli, with compounds S3–S6 showing promising results with MIC values below 25 mg/mL. These findings indicate the potential of these compounds as antibacterial agents. Overall, the successful synthesis and characterization of these novel derivatives open avenues for further research into their potential pharmacological applications. The findings of this study lay the foundation for future studies aimed at optimizing these compounds for enhanced antimicrobial activity and exploring their therapeutic potential in treating bacterial infections. [ABSTRACT FROM AUTHOR]

Acid catalysis plays a pivotal role in the industrial landscape due to its multifaceted contributions to various chemical processes in numerous sectors, including petrochemicals, polymers, food processing, and biodiesel production, among others. Sulfonated graphenes hold notable relevance as heterogeneous acid catalysts due to their unique combination of graphene's structural properties and the introduction of sulfonic groups as catalytic acid sites. Herein, we report the preparation of three sulfonated graphene‐based materials – sulfonated reduced graphene oxide (rGO‐SO3H), chlorosulfonated reduced graphene oxide (rGO‐HSO3Cl) and sulfonated graphene oxide (GO‐SO3H) – by different synthetic approaches. Physicochemical, textural, morphological, and acidic properties of all materials were characterized in detail by different instrumental techniques. Innovatively, these materials have been evaluated as heterogeneous acid catalysts in the solketal synthesis by acetalization of glycerol, which is considered an interesting building block to produce added‐value products. The density of acidic active sites and hydrophobicity were found to be conditioning parameters of the resulting catalytic activity in terms of conversion and selectivity. The best catalytic performance was obtained by rGO‐SO3H, reaching the maximum conversion towards solketal in 15 minutes under mild reaction conditions. The reusability and stability of all materials were also examined after three consecutive acetalization reactions with only a slight loss of catalytic activity. [ABSTRACT FROM AUTHOR]

Furfural is an attractive bio‐based platform chemical that has many derivatives of commercial interest. Herein, we show that the selectivity of the direct furfural reduction can be steered from 2‐methylfuran and 2‐methyltetrahydrofuran to furfuryl alcohol and tetrahydrofurfuryl alcohol by varying the ratio of formic acid and sodium formate. These reagents take the role of terminal reductants in the disclosed heterogeneous Pd‐catalysed process. We report the development and optimisation of the reaction conditions for three different products directly from furfural: 2‐methyltetrahydrofuran, tetrahydrofurfuryl alcohol and 2‐methylfuran which were obtained in 59 %, 46 %, and 63 % selectivity, respectively. Furthermore, the protocol uses commercially available Pd/Al2O3 as catalyst and the formic acid and sodium formate can be obtained from biogenous sources. [ABSTRACT FROM AUTHOR]

A unique bifunctional catalyst comprised of acid site containing, hierarchical ZSM‐5 (contains acid sites) supported RuCo bimetal, was synthesized using a facile incipient wetness impregnation method. The synergistic interaction between zeolite acid sites and bimetals of this bifunctional material significantly improves its performance as a catalyst of hydrogen producing, dehydrogenation of ammonia borane. [ABSTRACT FROM AUTHOR]

The catastrophic ramifications of fossil fuels on the environment have prompted the search for renewable energy sources. Over the recent decades, biodiesel has garnered attention as a promising direct alternative to diesel fuel; however, reliance on homogeneous catalysts and the requirement for refined vegetable oil feedstocks present financial and sustainability concerns. Thus, there exists a need for the development of sustainable and cost‐effective catalytic solutions. Herein, the application of lignin, an abundant and renewable biomass, as an effective heterogeneous catalyst is reported for biodiesel production via the esterification of oleic acid. Lignin is extracted from corn straw using sulfuric acid, which endows sulfonic acid groups (0.85 mmol g−1) to its structure allowing it to act as an acid catalyst without additional post‐treatments. Conversion of oleic oil to biodiesel is achieved at 97% using a 1:3 oleic acid to methanol molar ratio with a 5 wt.% catalyst loading at 90 °C after only 30 min. Moreover, the catalyst exhibits a remarkable turnover frequency of 2.61 min−1 proving its efficiency. These findings demonstrate that heterogeneous catalysts can be prepared from biomass waste offering a significantly cheaper and less intensive synthesis process and allowing for a paradigm shift to non‐edible and waste cooking oils. [ABSTRACT FROM AUTHOR]

Development of new organic synthetic methods fascinating the researchers which facilitating the increasing demands of the modern society, environmental friendly with high efficiency and low cost. The introduction of chromophores in an organic molecules facilitating intersystem crossing (ISC) to harvest both singlet and triplet excitons is also currently demanding field. We report a facile synthesis of symmetrical azines from carbonyl compounds and hydrazine hydrate with carboxylic acid esters as catalyst in methanol. This reaction presents a condensation of primary amino groups in hydrazine hydrate and carbonyl compounds took place simultaneously in a very short refluxing time. The prepared azines 1–10 were structurally analysed by various analytical techniques such as LC-MS1, H NMR13, C NMR, UV-Vis, FTIR and single crystal X-ray diffraction. Photoluminescence properties of prepared azines were recorded in CCl4 at 1 × 10−3 M and excitation range from 329 to 362 nm. The photoluminescence analysis results revealed that compounds 1–10 (except 8) were showed delayed fluorescence and 8 was showed fluorescence property. The photophysical properties of compounds 1–10 such as electron density and band gap energies was calculated by density function theory. This results revealed that the intra-molecular charge transfer occurs within the azines. The azine function in the azines enabling intersystem crossing hence, it is showing phosphorescence. [ABSTRACT FROM AUTHOR]

[Cp*Ir(R‐pica)Cl] (Cp*=pentamethylcyclopentadienyl anion, pica=2‐picolineamidate) complexes bearing carbohydrate substituents on the amide nitrogen atom (R=methyl‐β‐D‐gluco‐pyranosid‐2‐yl, 1; methyl‐3,4,6‐tri‐O‐acetyl‐β‐D‐glucopyranosid‐2‐yl, 2) were tested as catalysts for formic acid dehydrogenation in water. TOFMAX values over 12000 h−1 and 50000 h−1 were achieved at 333 K for 1 and 2, respectively, with TON values over 35000 for both catalysts. Comparison with the simpler cyclohexyl‐substituted analogue (3) indicated that glucosyl‐based complexes are much better performing under the same experimental conditions (TOFMAX=5144 h−1, TON=5000 at pH 2.5 for 3) owing to a lower tendency to isomerize to the less active k2‐N,O isomer upon protonation. The 5‐fold increase in TOFMAX observed for 2 with respect to 1 is reasonably due to an optimal steric protection by the acetyl substituent, which may prevent unproductive inner‐sphere reactivity. These results showcase a powerful strategy for the inhibition of the common deactivation pathways of [Cp*Ir(R‐pica)X] catalysts for FA dehydrogenation, paving the way for the development of better performing hydrogen storage systems. [ABSTRACT FROM AUTHOR]

A ring-opening protocol of epichlorohydrin with 2-ethylhexanol was investigated for the synthesis of the corresponding chlorohydrin ether. BuSnCl3 proved to be an efficient mild Lewis acid catalyst, yielding the product with high selectivity. A scalable flow synthesis was achieved by modifying the flow setup. The flow synthesis of the corresponding glycidyl ether from the chlorohydrin ether was also carried out in an efficient manner by using the basic treatment. [ABSTRACT FROM AUTHOR]

In this study, hydrogen production through the hydrolysis, ethanolysis, and methanolysis reactions of NaBH4 using adipic acid as a catalyst was investigated for the first time. Adipic acid solutions were prepared with methanol and ethanol at concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 M. In these reactions, NaBH4-MR (methanolysis) and NaBH4-ER (ethanolysis) reactions were carried out at 30, 40, and 50 °C with NaBH4 concentrations of 1.25%, 2.5%, and 5%. Hydrolysis reactions (NaBH4-HR) were conducted at 0.1 M under the same conditions. In the ethanolysis and methanolysis reactions at 30 °C, total hydrogen conversion was achieved at 0.3 M, 0.4 M, and 0.5 M. However, in the hydrolysis reactions, total hydrogen production was only obtained at 50 °C. It was observed that in the NaBH4-MR and NaBH4-ER reactions, total hydrogen conversion could be achieved within 4–5 s. The utilization of adipic acid as a catalyst for hydrogen production from NaBH4 through ethanolysis and methanolysis reactions is proposed as a highly efficient and fast method, characterized by impressive conversion rates. [ABSTRACT FROM AUTHOR]

The preparation and application of non-isocyanate polyurethane (NIPU) from biomass raw materials as a substitute for traditional polyurethane (PU) has recently become a research hot topic as it avoids the toxicity and moisture sensitivity of isocyanate-based PU. In the work presented here, self-blowing GNIPU non-isocyanate polyurethane (NIPU) rigid foams were prepared at room temperature, based on glucose, with acids as catalysts and glutaraldehyde as a cross-linker. The effects of different acids and glutaraldehyde addition on foam morphology and properties were investigated. The water absorption, compressive resistance, fire resistance, and limiting oxygen index (LOI) were tested to evaluate the relevant properties of the foams, and scanning electron microscopy (SEM) was used to observe the foams' cell structure. The results show that all these foams have a similar apparent density, while their 24 h water absorption is different. The foam prepared with phosphoric acid as a catalyst presented a better compressive strength compared to the other types prepared with different catalysts when above 65% compression. It also presents the best fire resistance with an LOI value of 24.3% (great than 22%), indicating that it possesses a good level of flame retardancy. Thermogravimetric analysis also showed that phosphoric acid catalysis slightly improved the GNIPU foams' thermal stability. This is mainly due to the flame-retardant effect of the phosphate ion. In addition, scanning electron microscopy (SEM) results showed that all the GNIPU foams exhibited similar open-cell morphologies with the cell pore sizes mainly distributed in the 200–250 μm range. [ABSTRACT FROM AUTHOR]

This study delineates the dependence of thermophysical behavior of acid‐epoxy vitrimers on their formulation. The stress relaxation due to the bond exchange reaction and the glass transition temperature of acid epoxy vitrimers are investigated, with respect to the influence of catalyst content and acid chain length. This is carried out for a range of dicarboxylic acids and catalyst concentrations formulated and characterized using calorimetry and dynamic mechanical analysis. The influence of acid chain length on the bond exchange rate, topological transition, and glass transition temperatures of the vitrimers is found to be significant. The activation energy of the exchange reaction varies over a wide range from 73 to 104 kJ/mol and the topology freezing temperature from 66 to 136°C with the behavior governed by the interplay between crosslinking density, network flexibility and density and distance of functional groups, with an increase of catalyst concentration leading to lower topological transition temperature and the dependence on chain length showing non‐monotonic behavior. The glass transition decreases by about 30°C as the carbon chain length increases from 6 to 14 carbons due to enhanced monomer flexibility and is not affected by the concentration of catalyst. [ABSTRACT FROM AUTHOR]

The production of nitric acid represents the primary source of nitrous oxide (N2O) emissions. During pilot-scale studies of N2O reduction on a low-temperature catalyst on nitric acid plants, it was observed that increasing the concentration of NH3 resulted in a decrease in the degree of N2O decomposition. This suggested that N2O was formed by the oxidation of NH3. Measurements at different temperatures, conducted after the N2O reduction trials, resulted in the N2O concentration at the inlet equal to the concentration at the outlet, indicating catalyst deactivation. To identify the causes of deactivation, the physicochemical properties of the catalyst were investigated. XRF analysis revealed the presence of sulfur. The results suggest the necessity of removing sulfur from the raw gas before the reduction of N2O on the low-temperature catalyst in practical applications. [ABSTRACT FROM AUTHOR]

Background: The efficient use of softwood in biorefineries is hampered by its recalcitrance to enzymatic saccharification. In the present study, the fungus Thermothielavioides terrestris LPH172 was cultivated on three steam-pretreated spruce materials (STEX180°C/auto, STEX210°C/auto, and STEX210°C/H2SO4), characterized by different hemicellulose content and structure, as well as on untreated biomass. The aim of the study was to map substrate-induced changes in the secretome of T. terrestris grown on differently treated spruce materials and to evaluate the hydrolytic efficiency of the secretome as supplement for a commercial enzyme mixture. Results: The cultivation of T. terrestris was monitored by endo-cellulase, endo-xylanase, endo-mannanase, laccase, and peroxidase activity measurements. Proteomic analysis was performed on the secretomes induced by the spruce materials to map the differences in enzyme production. Growth of T. terrestris on STEX180°C/auto and STEX210°C/auto induced higher expression level of mannanases and mannosidases of the GH5_7 CAZy family compared to cultivation on the other materials. Cultivation on untreated biomass led to overexpression of GH47, GH76, and several hemicellulose debranching enzymes compared to the cultivation on the pretreated materials. T. terrestris grown on untreated, STEX180°C/auto and STEX210°C/auto induced three arabinofuranosidases of the GH43 and GH62 families; while growth on STEX210°C/H2SO4 induced a GH51 arabinofuranosidase and a GH115 glucuronidase. All secretomes contained five lytic polysaccharide monooxygenases of the AA9 family. Supplementation of Celluclast® + Novozym188 with the secretome obtained by growing the fungus grown on STEX180°C/auto achieved a twofold higher release of mannose from spruce steam-pretreated with acetic acid as catalyst, compared to the commercial enzyme cocktail alone. Conclusions: Minor changes in the structure and composition of spruce affect the composition of fungal secretomes, with differences in some classes explaining an increased hydrolytic efficiency. As demonstrated here, saccharification of spruce biomass with commercial enzyme cocktails can be further enhanced by supplementation with tailor-made secretomes. [ABSTRACT FROM AUTHOR]

A highly efficient protocol was developed for the synthesis of fructone spice from the ketalization of ethyl acetoacetate with ethylene glycol utilizing the sulfonated polydivinylbenzene (PDVB-SO3H) solid acid catalyst. A comparative analysis revealed that PDVB-SO3H exhibited better catalytic activity and reusability than conventional H2SO4 and p-toluene sulfonic acid. The impact of reaction conditions, including temperature, reaction time, catalyst dosage, and molar ratio of reactants, was extensively investigated in order to optimize the reaction parameters. The results revealed the remarkable catalytic efficiency of PDVB-SO3H in synthesizing apple ester flavor, achieving a conversion rate exceeding 99% under reflux conditions with a ketone to alcohol ratio of 1.5. Furthermore, PDVB-SO3H solid acid demonstrated its versatility by enhancing the synthesis of a variety of fruit ketone flavors with high conversion rates. Notably, the catalyst displayed excellent recyclability, remaining active for up to six cycles without any noticeable decline in performance. Therefore, PDVB-SO3H solid acid exhibits immense potential for utilization in the chemical industry. [ABSTRACT FROM AUTHOR]

Biodiesel serves as a renewable, eco-friendly alternative fuel. Its production relies on converting triglyceride sources into methyl esters through transesterification. These triglycerides can be sourced from vegetable oils and animal fats. Previous studies often relied on acids and bases as catalysts. However, there's a lack of research exploring the use of modified zeolite and bentonite as catalysts, which hold the promise of higher yields compared to previous studies. In this study, biodiesel was derived from Calophyllum inophyllum via esterification and transesterification processes. Characterization of these catalysts was done using XRD and FTIR analyses. Transesterification to produce biodiesel occurred at temperatures ranging from 50 to 70℃ over a reaction period of 5 hours. The largest yield of biodiesel was obtained at 60℃, with 88.19% using modified zeolite catalyst, 78.84% using modified bentonite catalyst, and 82.36% using a blend of modified zeolite and bentonite catalysts in a 1:1 ratio. Biodiesel resulting from the highest yield using modified zeolite catalyst underwent characteristic testing in accordance with SNI standards. The findings revealed a density of 887 kg/m3, viscosity of 5.633 mm2/s, cetane number of 53, flash point at 121℃, and methyl ester content of 94.55%. [ABSTRACT FROM AUTHOR]

Reduction of nitric acid reaction (2NO + HNO3 + 3CH3OH → 3CH3ONO + 2H2O) can convert by-product nitric acid into raw material methyl nitrite in the coal to ethylene glycol (CTEG) technology. This not only realizes the efficient recycling of nitrogen resources but also plays a crucial role in mitigating environmental pollution. Despite being a promising catalyst, the Pd/C catalyst face challenges due to its high metal loading, substantial loss rate, and consequent issues of poor stability, presenting obstacles in meeting industrial requirements. To address this issue, a defect strategy has been employed to develop a low-loaded 0.3% Pd/NC catalyst with robust metal-support interaction, resulting in a significant enhancement of catalyst stability. Remarkably, even after undergoing five cycles, the catalyst maintains a high nitric acid conversion rate of 90%. This improved performance can be attributed to the strong metal-support interaction driven by electron transfer from the nitrogen-doped carbon (NC) substrate to the Pd nanoparticles evident in the Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma (ICP) results. This interaction effectively suppresses the leaching of the active Pd nanoparticles, leading to significantly enhanced stability and a noticeable reduction in the loss rate. Raman spectrum and electron paramagnetic resonance (EPR) results can further reveal that the increase in the defect density lead to the strong metal-support interaction after nitrogen doping (pyridinic-N-dominated). These findings highlight the significant potential of the Pd/NC catalyst and its applicability in expediting the industrialization process of catalyst. [ABSTRACT FROM AUTHOR]

Transfer hydrogenation of N‐heteroarenes was successfully achieved using a water‐soluble half‐sandwich Cp*Ir‐based catalyst containing a uracil‐based bifunctional abnormal NHC ligand, using HCOOH/HCOONa buffer solution as the hydrogen source. Reduction of N‐heteroarenes was shown to be highly pH‐dependent, and an acidic pH = 3.0 was found to be suitable for the best activity. The catalyst showed excellent functional group compatibility and high turnover number (up to 10,400), with catalyst loadings as low as 0.005 mol%. Finally, we demonstrated the catalyst's efficacy and applicability toward reusable and repetitive transfer hydrogenation using liquid/liquid extraction methodology, which underscored the significance of sustainable usage of noble metal catalysts in such transformations. [ABSTRACT FROM AUTHOR]

A detailed study on one-pot synthesis of 2,3-diaza-1,3-butadiene derivatives from various aromatic aldehydes and hydrazine by using MMZHY solid acid catalyst is reported. The role of the bifunctional nature of MMZHY and the effect of metal ions in the catalyst are described with a supportive mechanism. Both sym-metrical and unsymmetrical aldazines (hydrazone free) were prepared with excellent yields and characterized by 1H and 13C NMR spectra. The other advantages of the catalytic system like its easy preparation by the bottom-up method, reusability, multiporous nature which reduces diffusional limitations, easy separation, and mild reaction conditions with higher yield of products are also highlighted. [ABSTRACT FROM AUTHOR]

This study presents an innovative approach for the production of starch nanocrystals (SNCs) grafted with polycaprolactone (PCL). Corn starch was subjected to hydrolysis using sulfuric acid (H2SO4), resulting in the formation of SNCs. These SNCs were subsequently grafted with polycaprolactone using Maghnite-H+ (an Algerian modified montmorillonite clay) as a solid acid catalyst. The resulting nanomaterial, denoted as SNCs-g-PCL, exhibited improved hydrophobic properties. Fourier-transform infrared spectroscopy (FTIR) revealed the presence of a distinctive carbonyl C = O band at 1726 cm−1 in the SNCs-g-PCL, indicating successful grafting. Nuclear Magnetic Resonance of protons (1H-NMR) exhibited new signals from the protons of PCL in the SNCs-g-PCL. Dynamic light scattering (DLS) measurements demonstrated an increase in the diameter of the starch nanocrystals after PCL grafting. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed a reduction in crystallinity and a transition from well-defined SNCs nanocrystals to a disordered structure upon PCL grafting. Furthermore, the antioxidant properties of the SNCs, both before and after grafting, were evaluated using 1,1-diphenyl-2-phenyl hydrazine radical scavenging assays and ferric reducing antioxidant power assays. Nonetheless, the observed antioxidant activity was found to be comparable to that of ascorbic acid (vitamin C) with an EC50 (Half maximal effective concentration) of around 100 mg/ml. This study highlights the potential of SNCs-g-PCL nanocrystals as a promising nanomaterial with antioxidant properties, making them suitable for various applications in the fields of materials science. [ABSTRACT FROM AUTHOR]

A series of Mn+/silicalite-1 was prepared to be used as a Lewis acid heterogeneous catalyst for a one-pot multicomponent Biginelli reaction. The catalysts were characterized by FTIR, XRD, NH3-TPD, and BET. The mesoporous catalysts possess a pore diameter of 13.83 nm (138.3 Å), a surface area of 282.43 m²/g, and a pore volume of 0.98 cm3/g, which can facilitate the transport of reactants and products smoothly during the catalytic process. Besides the acidity of the catalyst, the maximum temperature of NH3-desorption plays an important role in the catalytic activity. Cr3+/silicalite-1 showed the most active catalyst, while Zn2+/silicalite-1 showed the most selective one. Besides DHPM derivatives as a major Biginelli product, C6-styril of DHPM and Knoevenagel products were isolated if the reaction was conducted using Cr3+/- and Fe3+/silicalite-1. Catalyst Cr3+/silicalite-1 can be used to produce DHPM attaching various substituents and showed a green catalyst potential due to its reusability capacity. [ABSTRACT FROM AUTHOR]

Para-aminophenol (PAP) was synthesized from nitrobenzene through a two-step homogeneous acid catalyst reaction. In the first step, the intermediate of phenyl hydroxylamine was synthesized from the reduction of nitrobenzene with zinc. Next, the intermediate undergoes a Bamberger rearrangement in the presence of sulfuric acid into PAP. The PAP was purified with toluene extraction, an adsorption process with activated carbon, and crystalized by adjusting the pH solution. The reaction temperature, H2SO4 concentration, and reaction time on PAP yield were also optimized and validated. The process validation result showed that about 46.60 % PAP yield and 80 % PAP purification were obtained within the conditional process, such as a reaction temperature of 70oC, H2SO4 concentration of 1.5 M, reaction time of 150 min, and crystallization temperature of 5oC. Furthermore, the PAP product was identified with FT-IR and UPLC-MS. FT-IR spectrum showed pattern similarity with the standard of PAP, and the molar mass of the PAP synthesized measured by UPLC-MS was 109.23 g/mole, similar to PAP in the literature. [ABSTRACT FROM AUTHOR]

First case of regiospecific formation of indole fused with a triterpene scaffold is observed. Starting from 3‐oxo‐24‐nor‐allobetulin Fischer reaction with phenylhydrazine under the influence of weak acid catalyst led to 3H‐indole (indolenine) 4. This process was accompanied by a change in the configuration of the methyl group at C‐4 that was confirmed by x‐ray diffraction method. On the other hand, 3,2‐indole 5 was synthesized under the influence of strong acid catalyst (using phenylhydrazine hydrochloride in AcOH acid or phenylhydrazine in MeOH with a few drops of HCl). [ABSTRACT FROM AUTHOR]

The researchers of this study synthesized a new magnetic solid acid catalyst by processing Fe3O4 with glycine, pyrrole-2-carbaldehyde, and sulfuric acid as an acid group via a simple method. Its chemical structure was determined through a variety of analyses, including Fourier transform infrared spectroscopy, vibrating sample magnetometer, thermal gravimetric/derivative thermal gravimetric, field emission scanning electron microscope, energy-dispersive X-ray spectroscopy (EDX), EDX-mapping, transmission electron microscopy, inductively coupled plasma, X-ray diffraction, and Brunauer–Emmett–Teller. Following this, this efficient strong solid acid catalyst was used for the synthesis of of 2-amino-3-cyano-4H-pyran and polyhydroquinoline derivatives (84–95% yield in 5–30 min and 88–96% in 5–15 min, respectively). The nano-catalyst could be easily separated from the reaction mixture using a permanent magnet and utilized up to five times without experiencing any significant decrease in its catalytic activity. The implementation of this method offers several benefits including effortless separation, excellent catalytic activity, environmentally friendly reaction conditions, relatively high product yield, and low cost. Moreover, the recent research has demonstrated the notable antiviral effects of certain pyran and quinoline derivatives against COVID-19. [ABSTRACT FROM AUTHOR]

A powerful carbon-based solid acid catalyst and furfural were obtained from rice straw (RS) biomass resource. The acid catalyst was prepared through the carbonization and sulfonation of RS. Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, N2 adsorption-desorption, and ammonia temperatureprogrammed desorption (NH3-TPD) were used to characterize the catalysts. The effect of sulfonation time (4 h to 16 h) on the structure and acidity of the catalysts was elucidated. After 16 h of sulfonation, the BET surface area and the total acidity of the catalyst reached 415 m2/g and 7.48 mmol/g, respectively. Moreover, strong acid sites accounted for more than 63% of acidity. The catalyst was then used for the conversion of RS into furfural in water. The influence of reaction temperature and time while using the catalyst on the conversion process was also investigated. The catalyst exhibited high activity in the conversion of RS, with a furfural yield of 68.3 g/kg RS at 160 °C in 5 h. [ABSTRACT FROM AUTHOR]

Objective: To synthesize bis-Schiff bases bearing thiobarbituric acid and to screen their anti-urease inhibitory potential. Methods: In this study, 1,3-dimethylbarbituric acid derivatives were synthesized by a four-step process. Using K2CO3, 2,4-dihydroxy benzaldehyde and chloro ethyl acetate were esterified in DMF in the first step under reflux condition. The reaction was then carried out by combining the esterified aldehyde with 1,3-dimethylbarbituric acid at room temperature for about an 1 h. Hydrazine hydrate was then mixed with compound (II) in ethanol solvent with acetic acid acting as catalyst. Finally, substituted aromatic aldehydes were treated with bis-hydrazide (III) using ethanol and acetic acid as a catalyst. Results: The newly synthesized compounds were screened for their urease inhibition (in vitro). Four analogs, including (IIIj) (IC50 = 15.22 ± 0.49 μM), (IIIg) (IC50 = 16.05 ± 0.16 μM), (IIIa) (IC50 = 16.29 ± 0.73 μM), and (IIIb) (IC50 = 21.17 ± 0.21 μM) were found most powerful inhibitors than standard thiourea (IC50 = 22.80 ± 2.20 μM). The urease inhibition was also seen in compound (IIIi), (IIIc), (IIIh), (IIIe), (IIId), and (IIIf) however it was less from standard. The structure stability and chemical reactivity of the compounds were checked by density functional theory (DFT) method. Furthermore, the molecular docking simulation was performed to check the protein (urease) and ligand interactions and binding affinities by using AutoDock Vina. Conclusions: The synthesized derivatives attributed temendous potential against urease enzyme. Compound (IIIj) was found as the most potent anti-urease agent. Additional research including taxicological and in vivo is necessary to know the safety, effectivness and mechanism of action of these potent molecules. [ABSTRACT FROM AUTHOR]

In the [Bmim]Cl reaction medium, five different acidic ionic liquids were used as catalysts to study the effects of reaction time, reaction temperature, system water content, catalyst dosage, microwave power, and other factors on cellulose hydrolysis under microwave irradiation. The results showed that in the [Bmim]Cl reaction system, using N-methylpyrrolidone methylsulfonic acid salt as a catalyst, controlling the microwave reaction time at 10 min, reaction temperature at 130 °C, catalyst dosage at 1 g/g (cellulose), water addition at 0.756 μL/g ([Bmim]Cl), and microwave power at 480 W, resulted in the best cellulose hydrolysis effect with a glucose yield of 74.49%. Compared to conventional heating, the glucose yield increased by 24% and the hydrolysis time was reduced by 77%. Microwave irradiation significantly enhances the cellulose hydrolysis process in an ionic liquid medium. [ABSTRACT FROM AUTHOR]

Linear chlorinated phosphazene acid is prepared using PCl5 and NH4Cl as raw materials. Using hexaethylcyclotrisiloxane as the monomer, 1,1,3,3-tetramethyldisiloxane or 1,3-divinyl-1,1,3,3-tetramethyldisiloxane as the end-capping agent, and linear chlorinated phosphazene acid as the catalyst, polydiethylsiloxane oligomers terminated with active Si-H or Si-CH=CH2 groups have been prepared. Using hexaethylcyclotrisiloxane and 1,3,5,7-octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane or hexamethyldisiloxane as the end-capping agent, or using hexaethylcyclotrisiloxane and octamethylcyclotetrasiloxane as comonomers, 1,1,3,3-tetramethyldisiloxane as the end-capping agent, copolymers containing active Si-H bonds and dimethylsiloxane segments have been prepared under the catalysis of linear chlorinated phosphazene acid. The effects of catalyst dosage, reaction temperature, reaction time, end-capping agent, and polymerization monomer dosage on polymer yield and structure were investigated. Using 300 ppm of linear chlorinated phosphazene acid, oligomers and copolymers containing an active Si-H bond and diethylsiloxane segment were prepared under mild conditions. The molecular weight of the obtained polymers was close to their designed values, but their PDI values were small. The highest yield of α, ω-bisdimethylsiloxyl-terminated PDES oligomers reached 93%. Using oligomers and copolymers containing Si-H bonds and diethylsiloxane segments as crosslinkers, a silicone gel containing diethylsiloxane segments was prepared by hydrosilylation reaction. With the introduction of a diethylsiloxane segment, the glass transition temperature of the silicone gel decreased relative to that of the PDMS oligomer, but the temperature at 5% weight loss in nitrogen atmosphere decreased from 347 °C to 312 °C. The mechanism of the ring-opening polymerization of hexaethylcyclotrisiloxane catalyzed by linear chlorinated phosphazene acid is also discussed. [ABSTRACT FROM AUTHOR]

This study is aimed at fabricating composite films by cross‐linking polyvinyl alcohol (PVA) and dialdehyde cellulose (DAC) in varying ratios using citric acid as a catalyst. The acetal formation between the two components was studied using FTIR. Characterizations of the physiochemical properties revealed that increasing the DAC ratio of the composite film improved the hydrophobicity, tensile strength and barrier properties (water vapour, UV and oxygen) of the films while reducing elongation at break (flexibility), swelling and solubility of the film in water. When the DAC ratio was elevated to 50%, the tensile strength was enhanced to 98 MPa. In comparison, flexibility diminished to 29%, the solubility of the film reduced to 10% and water vapour permeability was lower by two orders of magnitude than that of the control PVA film. The peroxide value of linoleic acid decreased from 21.2% ± 7.6 (packed with PVA film) to 9.9% ± 0.9 (packed with 50% DAC composite film) after 15 days. Furthermore, the composite films demonstrated effective absorption of UV radiation, with the order of effectiveness being UV‐C > UV‐B > UV‐A radiation. No significant difference in biodegradability was detected in the composite films with an increase in DAC ratio during indoor soil burial tests for 30 days. This study implies that the composite film could serve as an alternative sustainable packaging option, especially when transparency and high oxygen barrier properties are desired. [ABSTRACT FROM AUTHOR]

Liquid-phase oxidation of dearomatized oil distillate from a mixture of Azerbaijan crudes in the presence of homogeneous catalysts based on Mn(II), Cr(III), and Со(II) bromobenzoates was studied. These catalysts allow preparation of synthetic petroleum acids and hydroxy acids in high yield (>40 wt %). The influence of the kind of the catalyst on the composition of the oxidation products was examined. Manganese(II) bromobenzoate showed the highest catalytic activity. We have determined for it the optimum process conditions at the feed rate of 300 L/(kg h) and atmospheric pressure: oxidation time 5 h; catalyst concentration 1 wt %; 140°С. The total yield of petroleum acids under these conditions was 46%. [ABSTRACT FROM AUTHOR]

In the present study, a green and readily effective route is presented, using for the first time, methanesulfonic acid (MSA) as a catalyst to produce alkyl levulinates (ALs) via the addition of alcohols to α-angelica lactone (α-AL). A smooth procedure was developed that resulted in the production of high-purity ALs, with complete conversions and high yields (99.1–99.8%), within 20 to 60 min of reaction in the presence of 0.5 mol% MSA. The reactions were carried out solvent-free, at room temperature, and in atmospheric air. Reaction conditions were optimized, and equimolar amounts of alcohol reagent were used. This work presents the main advantages of the use of a catalyst (MSA) that is low cost, easily biodegradable, and does not release toxic gases into the environment, but has an acidic strength comparable to that of other mineral acids. Therefore, this study proves the remarkable efficiency of MSA as a catalyst in the synthesis of ALs through an economically and environmentally favorable route. [ABSTRACT FROM AUTHOR]

The management of coffee and peapod waste presents significant environmental challenges, with millions of tons generated annually, leading to disposal issues and resource inefficiencies. Hydrothermal processes offer a promising valorization method, though biomass characteristics significantly influence the resulting products. Biomass characterization revealed distinct profiles for coffee cherry waste (moisture: 10.94%, ashes: 7.79%, volatile matter: 79.91%, fixed carbon: 1.36%, cellulose: 27.6%, hemicellulose: 12.5%, and lignin: 13.7%) and peapods (moisture: 7.77%, ashes: 4.22%, volatile matter: 74.18%, fixed carbon: 13.0%, cellulose: 20.2%, hemicellulose: 17.4%, and lignin: 5.0%). Experiments were conducted in 100 mL and 500 mL hydrothermal reactors with varying conditions for temperature (120–260 °C), time (1–4 h), stirring (none and at 5000 and 8000 rpm), biomass/water ratio (1:5, 1:10, 1:20, and 1:40), particle size (0.5–5 mm), and catalysts (acids and bases). The results showed that peapods produced over 30 times more platform chemicals than coffee. High temperatures (over 180 °C) degraded peapods, whereas coffee yields increased. Both biomasses were influenced similarly by reaction conditions: lower biomass/water ratios, smaller particle sizes, acid catalysts, and no stirring increased yields. Peapods consistently had higher yields than coffee in all conditions. Biochar analysis revealed anthracite from coffee and coal from peapods. [ABSTRACT FROM AUTHOR]

Industrial sulfuric acid waste catalysts contain a large amount of vanadium, sodium, potassium, sulfur, and a small amount of aluminum, iron, and arsenic. They are often used as important raw materials for extracting vanadium and alkali metal salts. Rapid and accurate determination of relevant components in waste catalysts and leaching residues is crucial for their separation and extraction. On the basis of column chromatography separation, this article investigated the leaching rates of V, Na, S, and K in the samples after leaching treatment, which were 95.28%, 98.39%,98.88%, and 97.82%, respectively. SEM showed that the sediment dissolved and disappeared on the surface of the carrier and in the pores. At the same time, the inductively coupled plasma emission spectroscopy (ICP-OES) method was used for determination, and the spectral lines of each element (V 309.311 nm, Na 589.490 nm, K 766.490 nm, S 180.731 nm, Al 394.401 nm, Fe 238.204 nm, As 189.042 nm) were determined. The results showed that the mass concentration of each element was linear with emission intensity within a certain range, and the linear correlation coefficient of the calibration working curve was greater than 0.9999, except for arsenic, which was 0.999 7, The detection limit of each element was 0.004-0.017 µg/g, and the relative deviation (RSD,n=11) of the determination results excluding As was 2.2%. The other elements were less than 0.90%, and the recovery of the added standard was between 98. 9% and 102%. The accuracy and precision of the method can meet the requirements for testing various elements in industrial sulfuric acid waste catalysts, providing data reference for the content of each element in the leaching and separation process of waste catalysts. [ABSTRACT FROM AUTHOR]

The asymmetric synthesis of 3,4-dihydropyrimidin-2-(1H)-one thioacetals was achieved for the first time using a chiral imidodiphosphoric acid catalyst. The Biginelli reaction involving aromatic aldehydes, thiourea, and 1,3-cyclohexanedione as a multi-component reaction was conducted in ethyl acetate at 40 °C with a chiral imidodiphosphoric acid catalyst. Under mild conditions, a series of chiral polycyclic 3,4-dihydropyrimidin-2-(1H)-one thioacetals were obtained with high yields and excellent enantioselectivity (up to 99% ee). [ABSTRACT FROM AUTHOR]

AbstractIn this study, CuO@HNTs-SO3H was investigated as a novel eco-friendly heterogeneous solid acid catalyst prepared by straightforward co-precipitation method. Thus, the cost-effective CuO NPs was used to modify halloysite nanotubes initially, which were subsequently further functionalized with sulfonic acid. The prepared catalyst was analyzed by means of FT-IR, XRD, EDX, SEM and TGA methods. Its catalytic activity is investigated in the solvent-free one-pot condensation of various aromatic aldehydes, dimedone, and β-naphthol to produce tetrahydrobenzo[a]xanthen-11-one derivatives. A few benefits of the discovered method are its simple process, quick reaction time, high yields (96%), affordable cost, and the catalyst ability to be reused without losing its activity. [ABSTRACT FROM AUTHOR]

After optimization for retention of catalytic activity, 4‐chlorobenzoic acid emerged as the optimal catalyst for the aliphatic ketone Claisen rearrangement. The optimal catalyst enables a one‐pot, metal‐free, catalytic protocol from allylic alcohols to γ,δ‐unsaturated ketones. The optimized process tolerates a range of substrates, including substituents with acid‐labile protecting groups. Reaction monitoring and DFT studies of the aliphatic ketone Claisen process agree that the ultimate rearrangement step typically has the highest activation barrier. [ABSTRACT FROM AUTHOR]

We developed a second generation of Lewis acid catalyst enabling selective and user‐friendly phosphonylation of diverse alcohols. This one‐pot method utilizes P(III) reagent bis(2,2,2–trifluoroethyl) phosphite under mild conditions. Exploring the influence of metal selection in Lewis acid catalysts revealed four highly active complexes for alcohol phosphonylation: Zn(II), Al(III), Zr(IV), and Hf(IV). Notably, Hf(IV) displayed superior selectivity compared to the previously developed Zn(II) catalyst. [ABSTRACT FROM AUTHOR]

This review focused on the potential applications of sulfonated carbon–based heterogeneous acid catalysts for the hydrolysis of lignocellulosic biomass (LCB) fuel feedstock and the development of membrane electrode assembly (MEA) for the direct biomass redox flow fuel cell (DBRFFC). LCBs are hydrolysed to yield simple sugars, which are subsequently oxidized over catalysts in the anode tank of the DBRFFC to generate electricity. Ferric chloride used as a catalyst in the DBRFFC is not efficient for glucose production from LCB, such that the power performance of the DBRFFC is affected during glucose oxidation due to low glucose yield from LCB for electron generation. Sulfonated carbon–based solid acid catalysts (SCSACs) have been established as efficient catalysts for the hydrolysis of LCB and as metal catalyst supports for the fabrication of MEA for further oxidation of glucose and its oxidation by‐products. These capabilities of SCSACs can be explored and applied to significantly improve the power output of the DBRFFC through efficient hybrid catalyst design. There is still a scarcity of literature on this subject and their combination with ferric chloride to enhance glucose yield and oxidation in DBRFFC. This gap was filled by discussing the various types of sulfonated carbon–based catalysts, highlighting their synthesis routes, and their applications in organic compound synthesis, and membrane electrode development in DBRFFC. The knowledge derived will certainly be beneficial to researchers willing to improve the performance of DBRFFC through molecular catalyst design and electrode membrane development for application in DBRFFC. [ABSTRACT FROM AUTHOR]

Ammonia borane (AB), with high hydrogen density and stability under ambient conditions, readily releases hydrogen via catalyzed hydrolysis. However, ammonia, a byproduct of hydrogen release, limits its utilization. Citric acid, a safe and cost-effective acid catalyst, for the acid catalyst of AB hydrolysis was investigated in this study to mitigate ammonia emissions while enhancing hydrogen release. Maximal hydrogen release (3 eq.H 2) and ammonia emission suppression (<0.5 ppm) were achieved using a 2-mol/L AB aqueous solution adding into citric acid powder (molar ratio of AB: citric acid = 1:1). In contrast, the amount of hydrogen release at other concentrations and/or using the mixing method was below 2.7 mol/mol AB within several hours. Ammonia re-released even after hydrogen release in the case of high AB concentration (e.g. >4 mol/L AB aqueous solution with citric acid powder (molar ratio of AB: citric acid = 1:1)) in the solution because of formation of borate ester (1:2 borate–diol molar ratio) via mono-ammonium citrate (a borate-ester precursor), which was revealed by the solution NMR. These results reveal a cost-effective and simple on-way method for hydrogen release with suppressed impurities. Furthermore, understanding impurity generation mechanisms can contribute to utilizing AB-derived hydrogen. [Display omitted] • H 2 and NH 3 release from citric acid-catalyzed AB hydrolysis was evaluated by continuous measurement. • The theoretical maximum H 2 release and NH 3 suppression were achieved. • NH 3 release from ammonia borane was started after 5 h from the start of reaction. • The delayed NH 3 release was caused by the formation of borate ester. [ABSTRACT FROM AUTHOR]

Developing non‐noble metal catalysts that can efficiently and selectively hydrogenate arenes remains a significant challenge. In this study, we developed efficient Ni catalysts for the arene hydrogenation based on an organic acid‐regulated impregnation strategy. These easily accessible Ni catalysts demonstrated exceptional efficiency, selectivity, reusability, and good substrate compatibility. The influence of carbon chain lengths and side‐chain hydroxyl or amino groups on dicarboxylic acids used in the catalyst preparation was comprehensively investigated. Characterizations and kinetic studies demonstrated the influence of organic acids on the size of Ni nanoparticles, the proportion of metallic nickel, and the strength of surface acidity. These factors influenced the activation of arene and hydrogen, thereby affecting the hydrogenative activity. Notably, hydroxyapatite‐supported Ni catalyst, assisted by tartaric acid (Ni‐TA/HAP) with an appropriate tartaric acid‐to‐nickel ratio, resulted in relatively smaller Ni nanoparticles, an increased proportion of Ni0, and more acidic sites, thereby exhibiting the best hydrogenation performance. [ABSTRACT FROM AUTHOR]

The storage and transportation of hydrogen gas, a non-polluting alternative to carbon-based fuels, have always been challenging due to its extreme flammability. In this regard, formic acid (FA) is a promising liquid organic hydrogen carrier (LOHC), and over the past decades, significant progress has been made in dehydrogenating FA through transition metal catalysis. In this review, our goal is to provide a detailed insight into the existing processes to expose various mechanistic challenges associated with FA dehydrogenation (FAD). Specifically, methodologies catalyzed by pincer-ligated metal complexes were chosen. Pincer ligands are preferred as they provide structural rigidity to the complexes, making the isolation and analysis of reaction intermediates less challenging and consequently providing a better mechanistic understanding. In this perspective, the catalytic activity of the reported pincer complexes in FAD was overviewed, and more importantly, the catalytic cycles were examined in detail. Further attention was given to the structural modifications, role of additives, reaction medium, and their crucial effects on the outcome. [ABSTRACT FROM AUTHOR]

The absence of catalytic asymmetric methods for synthesizing chiral (hetero)bicyclo[n.1.1]alkanes has hindered their application in new drug discovery. Here we demonstrate the achievability of an asymmetric polar cycloaddition of bicyclo[1.1.0]butane using a chiral Lewis acid catalyst and a bidentate chelating bicyclo[1.1.0]butane substrate, as exemplified by the current enantioselective formal (3 + 3) cycloaddition of bicyclo[1.1.0]butanes with nitrones. In addition to the diverse bicyclo[1.1.0]butanes incorporating an acyl imidazole group or an acyl pyrazole moiety, a wide array of nitrones are compatible with this Lewis acid catalysis, successfully assembling two congested quaternary carbon centers and a chiral aza-trisubstituted carbon center in the pharmaceutically important hetero-bicyclo[3.1.1]heptane product with up to 99% yield and >99% ee. The absence of catalytic asymmetric methods for synthesizing chiral (hetero)bicyclo[n.1.1]alkanes has hindered their application in new drug discovery. Herein the authors report an enantioselective formal (3 + 3) cycloaddition of bicyclobutanes with nitrones using a chiral Lewis acid catalyst for the synthesis of hetero-bicyclo[3.1.1]heptane. [ABSTRACT FROM AUTHOR]

Catalytic esterification in water has been achieved with the aid of a commercially available polymer-supported lipase, Novozym-435. Remarkably, this well-known biocatalyst demonstrates significant activity towards esterification using just water as the reaction medium. This methodology features representative esterifications of complex acids and alcohols, in the presence of unprotected amines. The work disclosed leading to esters typically requires only two equivalents of alcohol, although conversion for water-soluble alcohols appears to require increased loadings. Recycling of both the aqueous medium and catalyst are documented, highlighting the potential of this new technology, especially using directed evolution on the enzyme involved. Pharmaceutically relevant compounds are efficiently esterified (e.g., Ibuprofen, Tolmetin, and Ticagrelor) and multi-step, one-pot chemoenzymatic sequences can be performed to demonstrate the robustness of this catalytic aqueous system. [ABSTRACT FROM AUTHOR]

The extraction of vanadium from spent industrial catalysts is a widely practiced process globally due to the large quantities of material available with appreciable vanadium content. However, some of these spent catalysts are unresponsive to established extraction methods because they have different properties. Therefore, separate studies are necessary to deal with specific cases. This work demonstrates how the leaching step can limit the recovery of vanadium to the solution before the coprecipitation step. The NH4Cl‐H2SO4 synergetic system achieved a high vanadium leaching rate of up to 95 %, resulting in the preparation of high‐purity NH4VO3 with 75.45 % V2O5 content. This demonstrates the potential of the prepared V2O5 as a precursor for vanadium materials used in sodium‐ion batteries, allowing for the adjustment of the valence of vanadium. The Na3V2(PO4)3@C particles exhibit a discharge capacity of 110 mAh g−1 at a current density of 0.1 C and 90 mAh g−1 at 1 C. The synergistic leaching system provides a sustainable method for the recovery and reuse of vanadium from spent vanadium catalysts. This contributes to recycling efforts and the development of sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

To eliminate the harm of nitrogen oxides to human health and ecological environment, selective catalytic denitrification using methane as a reducing agent (CH4-SCR) has received widespread attention. Developing highly active CH4-SCR denitrification catalysts has become a research focus of this technology. In this article, Co(x)/ZRP catalysts were prepared by impregnation method, and the effects of Co(x)/ZRP catalysts with different cobalt loading amounts on the denitrification performance of CH4-SCR were investigated. The physicochemical properties of Co (x)/ZRP catalysts were characterized using XRD, H2-TPR, Py-IR, NH3-TPD and NO-TPD methods. The CH4-SCR denitrification performance of Co(x)/ZRP catalysts was evaluated on fixed bed micro-reactor under atmospheric pressure. The results showed that the cobalt species in the Co(x)/ZRP catalyst were Co3O4. With the increase of cobalt loading, the Co3O4 grains became larger, the redox ability and NO adsorption and desorption performance of the catalyst were improved. With the increase of cobalt loading, the denitrification activity of Co(x)/ZRP catalyst first increased and then decreased, which was consistent with the variation of medium strong acid amount in the total acid of the catalyst. Among them, the Co(20)/ZRP catalyst had a higher amount of medium strong acid, and the CH4-SCR denitrification performance was good, with Tm of 342 °C, XNomax of 39.2%. The L-acid and medium strong acid content of the catalyst played an important role in the CH4-SCR catalytic denitrification activity of the catalyst. [ABSTRACT FROM AUTHOR]