Synthesis Reaction Research Articles

Synthesis, structure, and oxygen reduction reaction of three copper complexes supported by ethylenediamine derivatives with outer-sphere oxoboron clusters

Three copper complex borates, [Cu(en)2]·[B4O5(OH)4]·2H3BO3 (1, en = ethylenediamine), [Cu(Eten)2]·[B5O6(OH)4]2 (2, Eten = N-ethyl ethylenediamine) and [Cu(Dmen)2]·[B10O13(OH)6] (3, Dmen = N,N-dimethyl ethylenediamine) have been successfully synthesized and structurally characterized by single-crystal X-ray diffraction, PXRD, and FTIR. Their oxoboron clusters are [B4O5(OH)4]2−, [B5O6(OH)4]− and [B10O13(OH)6]2−, respectively. Copper ion was used as the central atom, ethylenediamine and its derivatives were selected as ligand. The structure of oxoboron clusters in 1, 2 and 3 can be modulated through varying ethylenediamine derivative ligand, as well as temperature and pressure of reaction system. These copper complex borates exhibited open framework formed by the interconnection of hydrogen bonds of oxoboron clusters. Moreover, the oxygen reduction reaction activity of these borate-based catalysts was investigated. The half-wave potential values of the products after heating1–3with carbon at 600 °C (1/C-600, 2/C-600 and 3/C-600) were 0.817, 0.80 and 0.73 V, respectively.

Sulfonated mesoporous TUD-1: An innovative environmentally friendly solid acid catalyst for various organic transformations

TUD-1, a novel sponge-like three-dimensional mesoporous silica material, was synthesized in one-step using a hydrothermal technique and triethanolamine as a template. To enhance its acidic properties, the TUD-1 material underwent sulfonation with varying amounts of sulfonic groups (1 and 3 wt%). Structural characteristics were determined using XRD, FTIR, Raman, BET analysis, HRTEM, SEM, and XPS. Surface acidities of the catalysts were evaluated through non-aqueous potentiometric titration and FTIR analysis of chemisorbed pyridine. The performance of catalysts was assessed in various reactions, including the Pechmann reaction, Friedel-Crafts acylation reaction, and Biginelli reaction for synthesis of 7-hydroxy-4-methyl-2H-chromen-2-one, aromatic ketones and 3, 4-dihydropyrimidin-2(1H)-one. The findings confirm that the TUD-1 mesoporous structure did not undergo any significant alteration post sulfonation. The sulfonated catalysts exhibited higher surface acidities than TUD-1. A correlation between surface acidity, particularly Brönsted acid sites, and catalytic efficiency in selected reactions was evident from both catalytic testing and characterization. Under moderate conditions, TUD-1-3SO3H exhibited outstanding catalytic performance and remarkable reusability across all selected reactions.

Basic microstructural, mechanical, electrical and optical characterisation of BaTiAl6O12 ceramics

In progressive particle or layered composites based on a combination of BaTiO3 and Al2O3, serving as e.g. ceramic harvesters, new phases are formed during heat treatment. The dominant one is BaTiAl6O12. This study provides information about the microstructural, mechanical and optical properties of the BaTiAl6O12 ceramics. The evolution of the phases during the solid-state reaction synthesis of the BaTiAl6O12 was monitored. The fully dense samples prepared by spark plasma sintering had indentation Vickers hardness and indentation elastic modulus within ranges of 10.1–13.7GPa and 132.0–187.0GPa, depending on loading force. The three-point bending tests of the BaTiAl6O12 samples resulted in flexural strength of 129.9MPa and fracture toughness of 1.8MPam1/2. The sample showed blue broad-band emission under UV excitation due to the charge-transfer transition of the Ti4+ and defect sites. The BaTiAl6O12 evinced low permittivity (ɛ′)=16 and dielectric loss (tanδ) <0.0003 at a frequency 1kHz.

Co-pyrolysis of fly ash with sewage sludge for PCDD/F removal.

Fly ash generated from municipal waste incineration (MWI) contains various toxic substances, and it has to be properly treated before disposal or reuse. Water washing and thermal pyrolysis can improve the destruction efficiency of PCDD/Fs in fly ash generated from municipal solid waste incinerators. Since sulfur oxides and nitrogen compounds generated by the heating of the sewage sludge poison the catalytic active sites for PCDD/Fs formation on fly ash surface, co-pyrolysis of fly ash with sewage sludge effectively inhibits precursor formation and de novo synthesis reaction, resulting in the great reduction of PCDD/F formation. The results of the pyrolysis at 350 °C show that the PCDD/Fs removal efficiencies based on mass concentration are over 99%. The results at 350 °C of different reaction times show that the reaction time of 10 min is sufficient to reach the European End of Waste criteria (≤ 20 pg TEQ/g) when the ratio of fly ash/sewage sludge is controlled at 1:1.

Innovative cascade reaction for 2H-indazole derivative synthesis.

In the realm of synthetic organic chemistry, by using a one-pot sequential combination of MCR, it is possible to manufacture chemical commodities (fine chemicals, agrochemicals, and pharmaceutical substances) that enhance our quality of life while generating less waste materials and increasing economic advantages. With this motivation, using a "one-pot" method with multiple components, we present a relatively simple way to make stereoselective substitute 2H-indazole analogues for this study. Firstly, functionalised 3-bromo-4-((methylthio)methyl) derivatives were produced using DMSO as both a carbon source and a solvent, in conjunction with TMSOTf as the Lewis acid promoter. These derivatives were then utilised in the synthesis of 2-H-indazole derivatives with an up to 80% yield using t-Bu3PHBF4 as the ligand and Cs2CO3 as the base, in the presence of a Pd catalyst at 100°C in an airtight tube. The phenyl ring is endowed with an electron-releasing group situated at position C-6, which efficiently synthesises several 2-H-indazol derivatives with cost-efficient and noteworthy yields by using this method. A comparative analysis of a number of halogen derivatives was also undertaken, using a variety of solvents that were classified according to their halogen group. To confirm the structures of the synthesised target compounds, spectrometric analysis (1H NMR, 13C NMR, and LCMS) was performed.

A cost-effective purification strategy of ultra-long AgNWs for enhancing stability and durability of AgNWs/PU sensor

A large amount of silver nanoparticles (AgNPs) and short-sized silver nanowires (AgNWs) were produced in the reaction of AgNW synthesis by the polyol method. These impurities immensely affected the practical application of AgNWs dispersion. To promote the electrical property of AgNWs, it is necessary to develop a cost-effective method to separate impurities in AgNWs dispersion. Herein, we developed a new purification strategy called centrifugation-sedimentation separation-centrifugation to purify the ultra-long AgNWs (average length of 98.26 μm and the aspect ratio of 1240) synthesized by an improved polyol method. The yield of sedimentation separation was up to 78.1 % in this strategy. Based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the sedimentation mechanism of the ultra-long AgNWs and impurities was systematically investigated. The AgNWs/polyurethane (PU) composite foam prepared by the impregnation method with purified ultra-long AgNWs demonstrated a superior conductivity of 13227 S/m, which was twice than that of the composite foam with unpurified ultra-long AgNWs. The resistance variation of the purified ultra-long AgNWs-5/PU sensor was only elevating 11 % after 100 cycles of 100 % strain compression at 1 Hz frequency, while the AgNWs-5/PU sensor prepared from commercial 20 μm AgNWs showed a resistance change of up to 492 %. Our study provides a low-cost, highly selective, and efficient purification strategy for ultra-long AgNWs dispersions, and also demonstrates that ultra-long AgNWs can enhance the sensing stability and durability of AgNWs/PU foam sensors.

Chemoselective Synthesis of α-Halo-α,α-difluoromethyl Ketones from Trimethyl(phenylethynyl)silane.

Here, we describe a novel strategy for chemoselective synthesis of α-halo-α,α-difluoromethyl ketones (-COCF3 and -COClCF2 motifs) from trimethyl(phenylethynyl)silane under catalyst-free and mild conditions. Commercially available Selectfluor or additional NaCl as halogen reagent was employed to complete this transformation, thereby demonstrating the potential synthetic value of this new reaction in organic synthesis.

Spatially Confined Radical Addition Reaction for Electrochemical Synthesis of Carboxylated Graphene and its Applications in Water Desalination and Splitting.

Due to the chemical stability of graphene, synthesis of carboxylated graphene still remains challenging during the electrochemical exfoliation of graphite. In this work, a spatially confined radical addition reaction which occurs in the sub-nanometer scaled interlayers of the expanded graphene sheets for the electrochemical synthesis of highly stable carboxylated graphene is reported. Here, formate anions act as both intercalation ions and co-reactant acid for the confinement of electro-generated carboxylic radical (●COOH) in the sub-nanometer scaled interlayers, which facilitates the radical addition reaction on graphene sheets. The controllable carboxylation of graphene is realized by tuning the concentration of formate anions in the electrolyte solution. The high crystallinity of the obtained product indicates the occurrence of spatially confined ●COOH addition reaction between the sub-nanometer interlayers of expanded graphite. In addition, the carboxylated graphene have been used for water desalination and hydrogen/oxygen reduction reaction. Therefore, this work provides a new method for the in situ preparation of functionalized graphene through the electrolysis and its applications in water desalination and hydrogen/oxygen reduction reactions.

In situ synchrotron X-ray diffraction study of synthesis reactions in mechanically activated Ti + Al powder mixture under linear heating conditions

In the present work, we studied the features of phase formation in mechanically activated Ti + Al powder mixture at various heating rates for the first time. The study was carried out using high-resolution diffractometry method which made it possible to study the processes of phase formation in situ at any stage of heating. It was established that ignition of the activated mixture can be initiated in the solid phase with an extremely low content of reaction products formed at the preheating stage. An increase in the heating rate leads to a decrease in the average burning rate and an increase in the ignition temperature. At high heating rates, the ignition is initiated in the presence of a liquid phase when the ignition temperatures are close to the melting temperature of aluminum. In this case, the content of reaction products formed during preheating stage is relatively high. It was found that the all main compounds presented in the equilibrium diagram of Ti-Al system are synthesized in parallel. The content of phases in the reaction products depends on the heating rate.

DNA Polymerase-Endonuclease Efficiently Synthesizes DNA to Prepare DNA Materials and Develop Novel Signal Amplification System.

DNA biosynthesis, a focus of fundamental and applied research, typically involves DNA polymerases by using templates, primers, and dNTPs. Some polymerases can polymerize dNTPs for DNA de novo synthesis, although this is generally to occur randomly. This novel synthesis method has garnered our attention and practical use. Herein, we observed that the addition of endonuclease significantly enhances the efficiency of the de novo synthesis reaction catalyzed by the DNA polymerase. We further investigated the reaction conditions that influence this efficiency. Building on the optimal reaction conditions, we developed a rapid and efficient strategy for preparing DNA hydrogel. Further, coupled with the CRISPR-Cas system, we developed a nucleic acid signal amplification system characterized by versatility, sensitivity, specificity, and no risk of aerosol contamination. We successfully detected viral nucleic acids in clinical samples. In summary, our study demonstrates the significant potential of DNA polymerase- and endonuclease-catalyzed DNA de novo synthesis in diverse applications.

Experimental PSA reactor for methanol-enhanced production VIA CO2 hydrogenation

Methanol synthesis via catalytic CO2 hydrogenation has emerged as one of the main ways to valorize CO2. The main problem is that the methanol synthesis reaction is thermodynamically controlled, and there is a parallel endothermic reaction, reverse water gas shift (RWGS), so low methanol production ratios are achieved.In this scenario, process intensification, particularly multifunctional reactors where reaction and separation occur simultaneously, is of great interest. Sorption-enhanced reaction processes (SERP) technologies are widely used in equilibrium-controlled processes to increase reagent conversion through selective product removal.Various authors have proposed SERP processes for CO2 hydrogenation to methanol, but most of them are simulations studies and it is difficult to find experimental data. The aim of the work is the experimental study of the CO2 conversion and selectivity to methanol of a SERP process based on a four-step PSA reactor. The process has been carried out with a commercial Cu/ZnO/Al2O3 catalyst and commercial 3A zeolite as adsorbent.Conversions beyond the equilibrium have been achieved in the SERP process, even complete conversion of CO2 at 50 bar, 250 °C, and 300 °C. In the cyclic process, high CO2 conversions far from equilibrium are achieved in all the range of temperatures, 200–300 °C. The best results of methanol yield are achieved at 250 °C and 50 bar, followed closely by 200 °C. It is worth mentioning that methane is detected in the transitory state at 300 °C and 50 bar. Also, the purge step has been studied, concluding that it is necessary for adsorbent regeneration, improving CO2 conversion in the cyclic steady state.

Numerical Simulation of In Situ Reaction Synthesis of TiC-Reinforced Steels from Elemental Fe-Ti-C Powders

Numerical Simulation of In Situ Reaction Synthesis of TiC-Reinforced Steels from Elemental Fe-Ti-C Powders

Cu-catalyzed click reaction in synthesis of eugenol derivatives as potent antimalarial agents

Eugenol(1), a terpenoid found in Ocimum, has various biological activities. The present study aims at extraction, isolation of the plant secondary metabolite eugenol (1), it’s derivatisation and structure identification as bioactive molecules. Synthesis and antiplasmodial activity (in-vitro and in-vivo), of a series of fourteen novel eugenol-based 1,2,3-triazole derivatives was done in the present study. Derivatives 5a–5n showed good antimalarial activity against the strain Plasmodium falciparum NF54. Derivative 5 m, IC50 at 2.85 µM was found to be several times better than its precursor 1 (106.82 µM) whereas the derivative 5n showed three fold better activity than compound 1, in vitro. The structure-activity relationship of the synthesised compounds indicated that the presence of triazole ring in eugenol analogues is responsible for their good activity. Compound 5m, was further evaluated for in-vivo antimalarial activity which showed about 79% parasitemia suppression. It is the first report on antimalarial activity of triazole eugenol derivatives.

Sustainable process intensification: Ultrasonic preparation of MIL-88A for benzoxazole synthesis

This study provides a biodegradable fumaric acid-based MIL-88A metal-organic framework, a cost-effective and non-toxic catalyst, for biologically active benzoxazoles synthesis. Initially, the ultrasonic approach is used for MIL-88A preparation at room temperature, significantly reducing the synthesis time compared to conventional heating protocols. The ultrasonic approach is once again used for the three-component production of benzoxazoles in the presence of MIL-88A catalyst. Subsequently, the benzoxazole reaction is accelerated and yields are also improved. Impressive yields ranging between 84 % and 96 % were obtained within one hour at room temperature for the three-component synthesis of benzoxazoles. Characterization techniques, including FT-IR, TEM, XRD, and SEM-EDS mapping, confirm the successful synthesis of MIL-88A. Moreover, a large-scale reaction for benzoxazole synthesis can be performed with minimal yield loss, indicating its practical application. Notably, fumaric acid, found in many fruits and vegetables, serves as the precursor for catalyst synthesis. Catechol, sourced from various plant sources, is employed for three-component production of benzoxazoles. By integrating sustainable techniques, including ultrasound-assisted synthesis and naturally available substrates, an innovative strategy was developed utilizing a renewable catalyst for an eco-friendly reaction.

Copper-Catalyzed Decarboxylation Cross-Coupling Cascade Reaction for Synthesis of Fused Dihydro-benzoxazinones.

A protocol for a tandem copper-catalyzed intermolecular decarboxylation cross-coupling cascade between o-bromobenzoic acids and proline or piperic acid has been disclosed. The developed protocol allows access to a variety of synthetically useful fused benzoxazinones scaffolds with high efficiency and good functional group compatibility. A mechanistically sequential approach for the decarboxylation and dehydration coupling process was presented.

Enhancing Charging Efficiency with Lithium Silicate in Silicon Composite Anode Materials Through Lithiothermic Reduction Reaction Synthesis

AbstractThis study synthesizes silicon (Si) powders with lithium silicates including lithium orthosilicate (Li4SiO4), lithium metasilicate (Li2SiO3), and lithium disilicate (Li2Si2O5), creating a composite structure of crystalline Si within a LixSiyOz matrix through the lithiothermic reduction reaction (LTRR) process. The reduction of Li‐ion consumption of the anode is investigated by 1) initial solid electrolyte interphase (SEI) layer formation, 2) SEI layer formation in response to Si expansion‐induced damage, 3) trapping of Li ions at Si defects, and 4) side reactions during initial charge and discharge cycles. Si/LixSiyOz electrode exhibits a specific capacity of 1522.2 mAh g−1 and an initial coulombic efficiency of 83.5%. The effect of the calendering process is observed, and a pressurization condition of 5000 kgf cm−2 or less is set, and the ICE is improved to 93.4%–96%. Si/LixSiyOz electrodes outperform pure crystalline Si electrodes in specific capacity (7.3%), ICE (42%), and retention characteristics (17%). The integration of the LixSiyOz matrix into Si anodes enhances Li‐ion transport and partially suppresses Si expansion. Additionally, the Si/LixSiyOz electrode exhibits superior rate capability in the 0.2–1.6 A g−1 range.

Late-stage diversification of bacterial natural products through biocatalysis.

Bacterial natural products (BNPs) are very important sources of leads for drug development and chemical novelty. The possibility to perform late-stage diversification of BNPs using biocatalysis is an attractive alternative route other than total chemical synthesis or metal complexation reactions. Although biocatalysis is gaining popularity as a green chemistry methodology, a vast majority of orphan sequenced genomic data related to metabolic pathways for BNP biosynthesis and its tailoring enzymes are underexplored. In this review, we report a systematic overview of biotransformations of 21 molecules, which include derivatization by halogenation, esterification, reduction, oxidation, alkylation and nitration reactions, as well as degradation products as their sub-derivatives. These BNPs were grouped based on their biological activities into antibacterial (5), antifungal (5), anticancer (5), immunosuppressive (2) and quorum sensing modulating (4) compounds. This study summarized 73 derivatives and 16 degradation sub-derivatives originating from 12 BNPs. The highest number of biocatalytic reactions was observed for drugs that are already in clinical use: 28 reactions for the antibacterial drug vancomycin, followed by 18 reactions reported for the immunosuppressive drug rapamycin. The most common biocatalysts include oxidoreductases, transferases, lipases, isomerases and haloperoxidases. This review highlights biocatalytic routes for the late-stage diversification reactions of BNPs, which potentially help to recognize the structural optimizations of bioactive scaffolds for the generation of new biomolecules, eventually leading to drug development.

Selective Hydrogenation of 2‐Methyl‐3‐butyn‐2‐ol Over Supported Cu Nanocatalysts

Nanosized copper is an interesting alternative to noble metal‐based catalysts in gas phase selective hydrogenation, but little is known about its performance in liquid phase catalysis. We investigated the activity and selectivity of 2 and 7 nm Cu on SiO2 catalysts for the three‐phase partial hydrogenation of 2‐methyl‐3‐butyn‐2‐ol, a highly relevant reaction for fine chemical synthesis. Next to the desired 2‐methyl‐3‐buten‐2‐ol, also 2‐methyl‐2‐butanol was formed as a result of over‐hydrogenation. The 7 nm Cu nanoparticles were intrinsically 2.5 times more active than 2 nm Cu (in terms of turnover frequency), and they were also more selective. At 180 °C the selectivity was only 15% at 50% conversion, but lowering the reaction temperature to 160 and 140°C led to 80% and even ~100% selectivity (at 50% conversion). The unselective step was around two times faster than the selective one, hence the high selectivity is due the stronger adsorption of the reactant than of the desired product, which limits over‐hydrogenation.

Pd-catalyzed asymmetric Larock reaction for the atroposelective synthesis of N─N chiral indoles.

Atropisomeric indoles defined by a N─N axis are an important class of heterocycles in synthetic and medicinal chemistry and material sciences. However, they remain heavily underexplored due to limited synthetic methods and challenging stereocontrol over the short N─N bonds. Here, we report highly atroposelective access to N─N axially chiral indoles via the asymmetric Larock reaction. This protocol leveraged the powerful role of chiral phosphoramidite ligand to attenuate the common ligand dissociation in the original Larock reaction, forming N─N chiral indoles with excellent functional group tolerance and high enantioselectivity via palladium-catalyzed intermolecular annulation between readily available o-iodoaniline and alkynes. The multifunctionality in the prepared chiral indoles allowed diverse post-coupling synthetic transformations, affording a broad array of functionalized chiral indoles. Experimental and computational studies have been conducted to explore the reaction mechanism, elucidating the enantio-determining and rate-limiting steps.

Photocatalytic CO2 reduction of CuO-Zn1-xCuxO (ZCO)/Ti3C2Tx MXene heterojunctions with enhanced interfacial charge transfer

Photocatalytic CO2 reduction reaction (CO2RR) synthesis of recycled fuel is a promising pathway to assist the mitigating fossil fuel depletion. Finding efficient and inexpensive high performance CO2RR semiconductor photocatalysts is a giant challenge in the field of photocatalytic reduction. This work constructs the novel-designed interfacial Schottky junction of CuO-Zn1-xCuxO (ZCO)/Ti3C2Tx via electrostatic spinning and electrostatic self-assembly techniques. The catalysts exhibit tight contact heterogeneous interface companies with enhanced CO2 chemisorption capability and proved by various characterizations for efficient carrier separation and migration capacity. The optimized ZCO/Ti3C2Tx nanosheet composites significantly improved their photocatalytic performance. The best samples yielded 5.855 and 2.518 μmol g−1 h−1 of CO and CH4, which are 6 and 1.73 times higher than the conversion of ZCO, respectively, and maintain stability after four cycles without the use of sacrificial agents. In addition, the mechanism and reaction pathways of the photocatalytic process are proposed through In-situ diffuse reflectance Infrared Fourier Transform Spectroscopy (In-situ DRIFTS) and X-ray absorption near edge structure (XANES) analysis. This work provides a new semiconductor/co-catalyst system for the photocatalytic reduction of CO2 and demonstrates that Ti3C2Tx MXene is a hopeful and inexpensive co-catalyst.