Reaction Conditions Research Articles

Rapid removal and catalytic decomposition of nitrate in anion-exchange resin containing gold nanoparticles toward purification of groundwater

We investigated the catalytic reduction of NO3– in various single-metal-introduced anion-exchange resins (AERs) in 1 bar H2 and observed that the reaction proceeded successfully. Among the metals considered in this study Au was optimal in terms of catalytic activity and ease of catalyst preparation, whereas Ru exhibited the highest activity. The AER with Au (Au@AER) containing the optimal amount of Au (0.3mmol/g) decomposed 0.38mmol/g of NO3– primarily into N2O under optimized reaction conditions (80°C and 5 h). The decomposition amount corresponded to 41 % conversion. The incorporation of Au into the AER increased its ion-exchange capacity from 1.18 (pristine AER) to 1.46mmol/g (Au@AER); in contrast, the ion-exchange equilibrium constant decreased from 1.4 to 0.83 L mol−1 owing to the change in the structure of the anion-exchange sites in the AER. Au@AER was reusable for ion-exchange removal and catalytic decomposition of NO3– up to five times without performance degradation.

Sulfur and nitrogen co-doped carbon nanotube membrane coating on paper-like sintered stainless steel fibres for catalytic phenol degradation in structured fixed-bed reactor

A new type of structured SNCNT/PSSF catalyst was successfully synthesized by chemical vapor deposition (CVD) method with thiourea as a precursor. Meanwhile, SCNT/PSSF was also synthesized, employing sublimed sulfur as a precursor for comparation. Both two catalysts were characterized by SEM, TEM, Raman, TG, FT-IR, and XPS. The results indicated that sulfur was presented in form of thiophenic sulfur in both catalysts, whereas nitrogen in SNCNT/PSSF presented as pyridinic nitrogen and graphitic nitrogen. Then, the performances of two catalysts for continuous catalytic wet peroxide oxidation (CWPO) of phenol were evaluated in a structured fixed bed. The results showed that SNCNT/PSSF exhibited higher activity within 7 h. This enhanced performance can be attributed to two key factors, as elucidated by density functional theory (DFT). Firstly, the incorporation of pyridinic nitrogen notably amplifies the adsorption energy for hydrogen peroxide (H2O2), achieving a remarkable value of −5.95 eV. Secondly, this modification boosts the affinity of sulfur atoms towards H2O2, promoting inter-fragment electron transfer and elongating the O-O bond in H2O2. Further insights into the reaction mechanism were gleaned from radical inhibition experiments and electron paramagnetic resonance (EPR) spectra, which confirmed the presence of hydroxyl radicals and singlet oxygen as the active oxygen species during the reaction. Moreover, the van der Waals interaction plays a pivotal role in enhancing the adsorption of H2O2 onto the confined inner surfaces of SNCNT, as opposed to a non-confined system. Upon optimizing the reaction conditions, the SNCNT/PSSF catalyst sustained an impressive 97.3 % conversion of phenol and 73.1 % TOC conversion within 7 h, demonstrating its exceptional stability and efficacy.

How substrate surface area and surface curvature determine kinetics and titanate formation during non-hydrothermal alkali treatment of titanium microspheres

Titanium surface nanostructuring using alkali treatment gains significant attention in a wide range of fields, such as biomaterials, (photo)catalysis, (metal/ion) sorption, CO2 capture, electrochromism and sodium-ion batteries. Even though the physicochemical properties and application potentials of the surface nanostructures are fairly well understood, there is still debate about their exact formation mechanism, limiting knowledge based structural control through altered synthesis conditions. Moreover, this knowledge is largely focused on hydrothermal synthesis conditions, whereas non-hydrothermal conditions might provide benefits towards industrial application. Also the impact of substrate properties, rather than chemical reaction conditions, on the nanostructure formation is only limitedly reported in literature. This work reveals new fundamental knowledge of non-hydrothermal alkali treatment of titanium, using microspheres by implementing, for the first time, in-situ hydrogen measurement during alkali treatment in combination with the ex-situ determination of the sodium and oxygen content in the recovered alkali treated samples, providing critical information on the role of dissolution apart from the precipitation process. The effect of surface area and surface curvature on the dissolution and precipitation process, and the resulting impact on the physicochemical properties of the obtained titanate layer is studied. This shows the much larger impact on dissolution in contrast to precipitation, knowledge that is lacking in literature, but important when implementing alkali surface nanostructuring on complex (e.g. 3D printed) substrates, and considering the prospective shift from lab-scale to industry. The Ti dissolution step was found to be mainly controlled by the total surface area, while the rate determining step was found to be the titanate precipitation, not influenced by either surface area or particle size.The changes in oxygen content in the samples after transformation of titanate into TiO2 provided a novel method for its quantification. The microspheres were analysed chemically (Raman), structurally (XRD) and morphologically (SEM, MIP), screening the effect of surface area, particle size and reaction time on the growth behaviour of the titanate layer. The porous layer structurally corresponds to Na2Ti2O4(OH)2 for all evaluated conditions, with pores in the range of 10 nm - 600 nm. Increasing surface area and particle size results in local and non-uniform titanate growth, while titanate nanowire and strut formation between the microspheres were enhanced by reduced microsphere size and prolonged reaction times.

Regeneration of bulk and silica-supported gallium oxide catalysts applied in the dehydrogenation of methanol to formaldehyde and hydrogen by reaction-oxygen regeneration cycles and oxygen pulses in the feed

The oxygen-free dehydrogenation of methanol to formaldehyde and hydrogen is a potential alternative to the established industrial oxidative dehydrogenation yielding aqueous formaldehyde solutions. Advantages are the production of anhydrous formaldehyde and of hydrogen as a valuable coupled product. However, fast deactivation of the catalyst occurs under the high-temperature reaction conditions mainly due to coking, which can be overcome by applying oxygen at a temperature high enough to allow fast oxidation of the carbon deposits but low enough to prevent the loss of Ga. From an engineering point of view, a stable reaction temperature in the catalyst bed and a high H2 yield have to be maintained, requiring that the catalyst enables methanol dehydrogenation, but not the oxidation of hydrogen to water. Thus, two modes of regeneration of GaOx-based catalysts were investigated using reaction − oxygen regeneration cycles and oxygen pulses in the feed. When using bulk Ga2O3 as catalyst and applying optimized reaction-regeneration cycles, a formaldehyde yield of 51 % and a hydrogen yield of 45 % at a stable methanol conversion of 65 % were achieved, whereas undiluted O2 pulsed into the feed every 30 s resulted in a continuous formaldehyde yield of 40 % and a hydrogen yield of 35 % at a stable methanol conversion of 59 % with water yields below 2 % and 4 %, respectively. The effects of the two operation modes on stability and product distribution are discussed in terms of the carbon removal rate from the surface, refilling of oxygen vacancies and parasitic reactions in the presence of oxygen. Specifically, the consumption of O2 did not lead to excessive water formation but preferentially effected the oxidation of the carbon deposits to CO and CO2.

Insights into the effect of Fe-Zn interaction on tunable reactivity in Fischer–Tropsch synthesis

In the Fischer–Tropsch synthesis (FTS) reaction, the intricate reaction conditions are prone to induce phase transitions in iron carbides, which markedly affect catalytic performance. Manipulating and stabilizing the active phase is paramount for ensuring the catalyst efficiency. In this study, we regulated the Fe-Zn interaction to investigate the influence of iron carbides and the characteristics of surface carbon species. The strong interaction significantly enhanced the adsorption and dissociation of CO on the catalyst surface, thereby facilitating the formation of carbon-rich Fe2(.2)C. Consequently, the FeZn-s catalyst exhibited the highest iron time yield (FTY) of 959 μmolCO·gFe-1·s-1. But meanwhile, the stronger Fe-Zn interaction also accelerated the carbon deposition rate and elevated the graphitization degree of the surface carbon, expediting the catalyst deactivation. These results provide an insight into the modulation and stabilization of iron carbides by adjusting the interaction between the Fe and supports, which inspires the further development of Fe-based catalysts for FTS applications.

Sustainable Synthesis of Benzimidazoles Catalyzed by Recyclable Functionalized Organosilica

A highly efficient protocol is herein reported for the preparation of benzimidazole compounds from o-phenylenediamine and various benzaldehyde derivatives in the presence of heterogeneous pyridinium protic ionic liquids supported on periodic mesoporous organosilica (PMO) in water. The synthesis of three novel benzimidazole derivatives is also reported. The proposed approach successfully afforded products in good yield under mild reaction conditions. PMO-Py-IL exhibited excellent catalyst activity and reusability for at least ten reaction cycles with no significant activity loss.

The Intra- and Intermolecular Friedel-Crafts Acylation of Amino Acid Derivatives in Stereo-retarded Manner

Abstract: The Friedel-Crafts acylation of natural or unnatural amino acids in stereoretarded manner is willing to prescribed here. Depending on its main skeleton, the typical intra- and intermolecular Friedel-Crafts reaction of amino acids can be differentiated. The unique amino acid’s general structure can contribute to the reaction between its carboxyl group and the side chain. Depending on the Friedel-Crafts reaction condition, the amino acid’s optical retention can be retarded. This perspective can contribute to the development of this one-century reaction in the field of organic chemistry.

Long-lived carriers-promoted photocatalytic deuteration of halides with D2O as the deuterium source over Cu doped quantum dots

Deuterium labeling is a highly valuable yet challenging subject of research in various scientific fields. Conventional deuteration methods often involve harsh reaction conditions and suffer from limited reactivity and selectivity. Herein, we report a visible light–driven C–X (X = halogen) to C–D (D = deuterium) exchange strategy over copper-doped cadmium sulfide quantum dots (Cu-CdS QDs) under mild conditions, eliminating the need for noble metal catalysts and expensive deuterium sources. The conversion of aryl halides into deuterated products using Cu-CdS QDs reaches up to 99%, which is four times higher than that achieved using pristine CdS QDs. The substantial enhancement in the photocatalytic activity of the QDs can be primarily attributed to the generation of long-lived charge carriers (approximately 6 μs) induced by Cu doping. Mechanistic studies reveal that the Cu dopants considerably retard the recombination of photoinduced carriers by creating intermediate energy levels that serve as hole trapping centers in CdS QDs, thereby improving the electron utilization efficiency in energetically demanding photoreduction reactions. Additionally, the introduction of Cu increases the energy offset between the conduction band of CdS QDs and molecular acceptors, facilitating the electron transfer process. Upon visible light irradiation, a series of aryl halides can be efficiently converted into the desired deuterated compounds using D2O as the deuterium source. This work demonstrates that regulating charge carrier dynamics in ultrasmall QD-based photocatalysts is a promising strategy for promoting organic transformations.

Fabrication and Electrochemical Evaluation of Cobalt Sulfide for Energy Storage Application

This work significantly contributes to this field by focusing on the synthesis and application of cobalt sulfide (CoS) as an innovative electrode material. Utilizing a straightforward hydrothermal process, we successfully synthesized CoS, emphasizing the optimization of reaction conditions. This included a detailed exploration of different solvents, primarily water and ethanol, to determine their impact on the final product. A comprehensive characterization of these parameters was conducted, shedding light on their crucial role in the material’s performance. The electrochemical attributes of the CoS electrodes were tested using cyclic voltammetry and galvanostatic charge discharge techniques. These investigations revealed that the CoS variant labeled as CoS_1 and CoS_2 demonstrated improved electrochemical properties. CoS_2 exhibited a specific capacitance of 360.0 Fg−1 at current load of 1.0 A/g. This superior performance of CoS_2 is largely attributed to its unique structural properties. The porous nature of CoS_2, coupled with its high surface area, plays a crucial role in enhancing its electrochemical capabilities. Furthermore, the material displayed impressive cyclic stability, maintaining up to 82.0% of its original capacitance. This level of durability highlights its suitability for long-term applications in energy storage devices. When tested in a three-electrode assembly, both CoS_1 and CoS_2 electrodes exhibited promising results. However, the distinct advantages of CoS_2, particularly in terms of capacitance and stability, underscore its potential as a superior candidate for energy storage applications.

Comparison of thermo-catalytic and photo-assisted thermo-catalytic conversion of glucose to HMF with Cr-MOFs@ZrO2

Abstract Thermo-catalytic and photo-assisted thermo-catalytic are two effective pathways for conversion of glucose. Thermo-catalytic and photo-assisted thermo-catalytic conversion of glucose was studied with Cr-MOFs@ZrO2 as catalysts in nitrogen atmosphere at 150 °C. Cr-MOFs@ZrO2 possesses simultaneously Lewis acid sites as well as Brønsted acid sites, and also has strong Brønsted acidity, so it can exhibit good thermos-catalytic performanc. When the glucose was 3 g/L, the reaction was carried out at 150 °C for 2 h with DMF as solvent, the glucose conversion was 97.9% while the HMF yield was 38%. The yield of HMF can be increased to 51.1% by adding 500w xenon lamp irradiation on the basis of thermal catalytic reaction condition. A comparison of the two reactions revealed that light-assisted thermal catalysis was more favorable for the reaction.

Hydrogen spillover enhances the selective hydrogenation of α,β-unsaturated aldehydes on the Cu–O–Ce interface

The industrially important selective hydrogenation of α,β-unsaturated aldehydes to allyl alcohol is still challenging to realize using heterogenous hydrogenation catalysts. Supported Cu catalysts have shown moderate selectivity, yet low activity for the reaction, due to the electronic structure of Cu. By anchoring atomically dispersed Pd atoms onto the exposed Cu surface of Cu@CeO2, we report in this work that hydrogen spillover activates the inert metal-oxide interfaces of Cu@CeO2 into highly effective and selective catalytic sites for hydrogenation under mild reaction conditions. The as-prepared catalysts exhibited much higher catalytic activity in the selective hydrogenation of acrolein than Cu@CeO2. Comprehensive studies revealed that atomically dispersed Pd species are critical for the activation and homolytic splitting of H2. The activated H atoms easily spill to the Cu–O–Ce interfaces as Cu-Hδ- and interfacial Ce–O-Hδ+ species, which makes the Cu–O–Ce interfaces as the active sites for the hydrogenation of polar C=O bonds. Moreover, the weak adsorption of allyl alcohol on the Pd and the Cu–O–Ce interfacial sites prevents deep hydrogenation, leading to selective hydrogenation of several α,β-unsaturated aldehydes. Overall, we demonstrate here a synergic effect between single atom alloy and the support for activation of an inert metal-oxide interface into selective catalytic sites.

The impact of energy flow on catalytic behavior in advanced DOC+SCR emission control systems

To further improve the catalytic efficiency of the aftertreatment system in exhaust conditions, the exhaust decoupling system is employed to investigate the effect of energy flow on aftertreatment catalytic systems (SCR & DOC+SCR) at wide engine load conditions (10–100 %). The physicochemical properties of particulate matter (PM) are analyzed by transmission electron microscopy (TEM). Furthermore, the energy flow and catalytic performances under the World Harmonized Transient Cycle(WHTC) are revealed. The research results exhibited that the energy distribution of exhaust in “DOC+SCR” was 10–15 % higher than that in “SCR” under steady state conditions, the provision of additional activation energy enhances the catalytic reaction, thereby improving the rate of the reaction, particularly in terms of NOx catalytic efficiency. On the other side, under transient conditions, the energy distribution of exhaust in “DOC+SCR” was 8.72 % higher than that in “SCR”. The NO/NO2 ratio remains stable value after the exhaust passing through DOC, thereby promoting the formation of rapid SCR reaction conditions. By revealing the PM microstructure, DOC enhances PM’s microcrystalline tortuosity and reduces particle size, thereby improving its oxidation reaction characteristics through combined catalysis. Simultaneously, this study demonstrates that the optimized combined catalytic method holds great potential for complete PM treatment.

Photochemical Fluoroalkylation and Alkylthiolation of o‐Cyano and o‐alkynyl Acrylamides: Pendant Functionality Led Divergence in Annulations

A visible‐light‐mediated, organophotocatalyzed cascade perfluoroalkylation and alkylthiolation of o‐cyano and o‐alkynyl acryla‐mides is reported. The reaction exhibits wide scope and provides polyfluorinated 1,3‐quinoline diones and trifluoromethylated fused tricyclic quinolinones under mild reaction conditions and in good yields. Access to a variety of molecular architectures and the synthetic application of aliphatic thiols are the highlights of this reactivity manifold.

Mild and Efficient Synthesis of Para-Substituted 2-Hydroxymethyl Piperazine

Abstract: 2-Hydroxymethyl piperazine is a crucial structural unit and essential intermediate in the drug development process. However, there are few reported methods for synthesizing 2- hydroxymethyl piperazine substituted at position 5. Herein, the 2-hydroxymethyl piperazines are synthesized from serine methyl ester hydrochloride and N-Boc-L-amino acids through a four-step reaction of condensation, deprotection, cyclisation, and reduction. This synthetic route has several advantages, including mild reaction conditions, availability of reagents, non-racemic composition, and the potential for gram-scale synthesis. In this study, we present a mild and effective synthetic method for preparing para-substituted 2-hydroxymethyl piperazine.

Efficient epoxidation of styrene over single-atomic copper-doped ordered mesoporous alumina (Cu-OMA) composited with carbon nitride

The present study assessed the catalytic performance in epoxidation of styrene using tert-butyl hydroperoxide (TBHP) as an oxidant over single-atomic copper-doped Ordered mesoporous alumina (Cu-OMA) composited with g-C3N4 (CN). The thermal treatment at three temperatures (300, 500, 700°C) provided a facile mean to modify the texture and electronic structure of the Cu-OMA@CN composite. The X-Ray absorption spectroscopy proved the single-atomic Cu-O-Al and Cu-O-C in Cu-OMA@CN-500 catalyst. Catalytic reaction parameters, namely temperature (60-80°C), catalyst amount (10-70 mg), substrate/oxidant ratio (1:1-1:3), and solvents (acetone, ethanol, acetonitrile, N, N-dimethylacetamide) were optimized to obtain high conversion of styrene and selectivity to styrene epoxide. Under the optimized reaction conditions (75°C, 30 mg of catalyst, 1:2 of styrene/TBHP and acetonitrile as solvent), the conversion decreased in the order of Cu-OMA@CN-500 > Cu-OMA@CN-300 > Cu-OMA@CN-700. This sequence was related to the formation of electron-rich single-atom copper sites, high surface area, medium alkaline environment of Al2O3 and high content of graphic nitrogen species. The most active Cu-OMA@CN-500 catalyst displayed a high styrene conversion (87.2%) and striking selectivity to styrene oxide (90.0%). Its catalytic activity was retained after five recyclability tests. The possible catalytic mechanism for epoxidation of styrene over Cu-OMA@CN-500 was tentatively proposed.

Transition Metals Catalyzed Direct C-H Chalcogenation of Arenes and Heteroarenes

Abstract: Transition metals catalyzed C-H bond activation reactions have appeared as an emerg-ing field to introduce different functional groups in the inactivated saturated and unsaturated C-H bonds. C-S and C-Se bond constructions in aromatic scaffolds are very interesting due to the im-portant applications of organochalcogen reagents in pharmaceutical chemistry and the material world. The introduction of sulphur or selenium moiety to an inert C-H functionality of an arene under transition metal catalysis has become one of the prime challenges and targets in recent years. In this perspective, various transition metals such as Cu, Ni, Co, Pd, Rh, Ru etc. have been extensively studied. Aromatic arenes owning bearing suitable directing groups appeared as the most promising coupling partners to selectively synthesize differently substituted aryl sulfones and aryl sulfides/selenides. The synthetic strategies were highly convenient owing to the regiose-lectivity of products, broad substrate scope, mild reaction conditions and excellent functional group tolerance. The current review article comprehensively summarizes the extent of C-S/Se bond formation via transition metal-catalyzed C-H bond activation with the assistance of directing groups to govern the site selectivity.

Biotransformation of Cinnamic Acid, Cinnamaldehyde, Furfural and Epoxidation of Cyclohexene by Plant Catalase

Background: Epoxides are widely useful in various fields such as pharmaceuticals, pesticides, cosmetics, polymer synthesis, fragrance compounds, and food additives. However, the synthesis of epoxides involves heavy metal catalysts and toxic, unstable organic catalysts which causes serious environmental and safety concerns. In recent years, biocatalysts have received a great deal of interest in the synthesis of olefin-derived epoxides due to their mild reaction conditions, environmental friendliness, good selectivity, and sustainability. This study focuses on catalases as a biocatalyst for potential epoxidation reactions of olefins. Objective:: To determine the possibility of using biocatalyst catalase from a novel source Sechium edule (squash) for epoxidation of olefins in the presence of H2O2. Methods: UV-Vis spectrophotometer was used to monitor the formation of epoxide from substrates- cyclohexene, cinnamic acid, cinnamaldehyde, furfural in acetonitrile solvent and a suitable aliquot of the enzyme solution in the presence of H2O2. The products formed were analyzed using FTIR and GC-MS. For the immobilized enzyme, chitosan beads activated with TPP were used in place of the enzyme and a similar procedure was followed for the analysis. Results: Four different olefin substrates (cyclohexene, cinnamic acid, cinnamaldehyde, and furfural) were selected to study the catalysis reaction of epoxidation by the catalase enzyme. The course of the epoxidation was monitored by UV-Vis, FTIR, and GC-MS methods. However, under optimized reaction conditions and spectral analysis, further confirmed by GC-MS, data showed only epoxide formation from cyclohexene. CAT completely catalyzed other olefins like furfural, cinnamic acid, and cinnamaldehyde into its degraded products biochemically. Therefore, cyclohexene was selected for further immobilization studies and the identified metabolites of olefins and their degradation mechanism. Major biodegradation products of cinnamic acid were found to be styrene( m/z 104.0) and benzaldehyde(m/z 105.0). GC-MS data of biotransformation of cinnamaldehyde, identified 2,4 dimethyl benzaldehyde(m/z 133) as the main product. The catalytic biotransformation of furfural investigated by GC-MS data identified 2,5 dimethyl benzaldehyde (m/z 133), dodecanol (m/z 181) and Pentanoic acid, 5 hydroxy, 2,4 dibutyl phenyl ester(m/z 306) as the major product. Three major oxidized products were detected in GC-MS data from the epoxidation of cyclohexene viz., cyclohexane diol(m/z 116), cyclohexene epoxide-1-ol(m/z 110), cyclohexene epoxide-1-one(m/z 110). Conclusion: In this investigation, catalase purified from Sechium edule(squash) was developed as an efficient catalytic tool for the biotransformation of olefins and selective epoxidation of cyclohexene. Under optimized conditions, the experimental results revealed the main products found in cinnamaldehyde as benzaldehyde (m/z 133.0) and cinnamic acid as benzaldehyde (m/z 133), styrene (m/z 104.0) and benzoic acid (m/z 122.0), while the data from furfural oxidation could not be justified from previous studies. The optimal concentration of CH3CN solvent for cyclohexene epoxidation was found to be 4 mM. Enzymatic characterization of free and immobilized catalase on chitosan was investigated using cyclohexene as a variable substrate and found to be 0.017 mM, 83.33 μmol/min for Km and Vmax values, pH 6.8 and 30˚C for free CAT and 0.03 mM, 200 μmol/min, pH 7.6 and 35˚C for immobilized one. Immobilization increases the thermal stability of the CAT and changes the pH to alkalinity. The possible oxidation of cyclohexene was deduced as the radical chain mechanism for the generation of epoxide with the key products obtained as cyclohexane diol(m/z 116), cyclohexene epoxide-1-ol(m/z 110) and cyclohexene epoxide-1-one(m/z 110). The reusability of the biocatalytic tool opens up the opportunity to reduce the cost of various catalytic reactions. Further studies can focus on the separation and advancement of epoxide yields, improved immobilization strategy for maximum repetitive cycles, and chemo-enzymatic epoxidation on biological olefins.

Controlled two-step synthesis of n-type conjugated ladder polymers using a flow reactor

The coplanar backbone of conjugated ladder polymers (cLPs) enhances electron transfer and π-π interactions, making cLPs promising materials for various applications in organic electronics and optoelectronics. Nevertheless, the limited solubility and intricate synthetic processes for cLPs make it challenging to control their molecular weight and corresponding properties, and pose as significant obstacles to their widespread application. Here, an n-type cLP, PNDI-2BocL, was synthesized using a flow reactor for the first time, with controlled molecular weights. The polymerization reaction conditions to synthesize a precursor polymer, PNDI-2Boc, were first optimized in flow, followed by sequential ladderization in batch through the injection of an acid solution. The reaction time of polymerization was varied from 7.5 to 15 min, yielding soluble PNDI-2BocL with a number-averaged molecular weight (Mn) ranging from 9.8 to 54.0 kg/mol with a deviation of 11 %. Additionally, 15 min of polymerization and ladderization were successfully conducted in a single flow system sequentially for the first time. In the molecular weight-dependent studies, higher optical absorption at longer wavelengths, increased degrees of crystallinity, and higher electron mobilities in organic field-effect transistors (OFETs) were observed for higher molecular weight PNDI-2BocL. Our results highlight the importance of controlling the molecular weights of cLPs and demonstrate that the flow synthesis technique provides a viable solution for synthesizing soluble cLPs in a controlled, reproducible, and rapid manner.

Elucidating the scale-up potential of biogenic magnetized nanocatalyst towards intensified biodiesel production

The current investigation delved into biodiesel synthesis from castor oil (CO) employing a magnetic nanocatalyst contrived from waste Citrus limetta peel ash (CLPA@Fe3O4). SEM, TEM, EDAX, XRD, XPS, VSM, and FTIR were used meticulously to analyze the synthesized catalyst. The catalyst’s core–shell arrangement kept its regulated size and shape and enhanced its surface properties, significantly increasing its stability. The optimal biodiesel yield of 97.92 % was accomplished utilizing CLPA@Fe3O4 catalyst through transesterification under the ideal reaction conditions of 30 wt% methanol concentration, the catalyst of 6 wt%, 60 °C temperature, and 3 h reaction time. The thermodynamics study advocated the transesterification process to be endothermic and nonspontaneous, while the kinetic tests were revealed to obey pseudo-first-order kinetics. The transesterification of CO employing the current catalyst was found to have an activation energy of 33.138 kJ mol−1. Nevertheless, an extraneous magnet could recover the prepared magnetic iron oxide-supported nanocatalyst from the reactor, as the catalyst showed a strong magnetization of 31.56 (emu/g). The catalyst showed excellent reusability up to 80 % for 6 consecutive cycles. The turnover frequency of the catalyst was ascertained to be 0.011 mol g−1.h−1, which measures the ability to drive biodiesel synthesis. The conversions from CO to biodiesel were validated via FTIR and GC–MS analysis. It is essential to highlight that biodiesel’s key fuel properties align with the standards set by ASTM D6751, indicating promising prospects for its future industrial use. The life cycle cost analysis of the catalyst and biodiesel, i.e., USD 0.533/kg and USD 1.005/L, indicates excellent potential for commercialization. Lastly, using creative bibliometric analysis to identify the gaps in the literature, the study made recommendations for the synthesis of biodiesel utilizing nanocatalyst.

Sustainable and versatile Aza-Michael additions promoted by acidic ionic liquids

Acidic ionic liquids are a subset of ionic liquids where the cation or anion possess acidic properties with huge applications in various fields. Here we describe environmentally safe and highly efficient conjugate addition of aromatic and aliphatic amines to α, β-unsaturated compounds in the presence of novel acidic ionic liquids. The acidic ionic liquid catalyst was prepared by combining benzyl chloride with 2-(dimethylamino) ethanol and SnCl2 in a simpler manner. The resulting acidic ionic liquid was characterized using SEM, EDS and FTIR spectroscopy. In the presence of ionic liquids, a wide variety of amines undergo facile conjugate addition to α, β-unsaturated compounds affording the corresponding β-amino compounds in good to excellent yields (72–97 %), shorter reaction times (1–4 h) and mild reaction conditions (60 °C). Furthermore, the study demonstrated the sustainability of the process by showcasing that the acidic ionic liquids could be reclaimed and reused for up to five cycles without compromising their catalytic effectiveness.