Reaction Of Acid Research Articles

Microwave-assisted green synthesis and molecular docking study of some new 4-thiazolidinone derivatives as possible bioactive agents

We have developed an economical and environmentally friendly microwave-assisted efficient method for the synthesis of a series of new 4-oxo-thiazolidine derivatives (4a-d). The method involves microwave irradiated cyclocondensation reaction of Schiff bases (3a-d) and thioglycolic acid in drug master file (DMF). 4-oxo-thiazolidine derivatives (4a-d) was also synthe 4-Oxo-Thiazolidine derivatives were also synthesized by conventional heating procedures and consequence were Compared with Microwave assisted green method. The results suggest that microwave-assisted syntheses lead to higher yields within very short reaction times. Antimicrobial screening of all the synthesized compounds was carried out using Gram-positive strains Staphylococcus aureus and Gram-negative strain encompassing Escherichia coli, Proteus vulgaris, and Salmonella typhi. The results were compared with the standard drug chloramphenicol. All the synthesized compounds were subsequently examined using molecular docking experiments against peptide deformylase (PDB ID: 1G2A), which evaluates the binding interaction of ligands with enzyme active sites.. KEYWORDS :Microwave irradiation, Thiazolidinone, Molecular docking, Peptide deformylase, Antimicrobial screening.

Cerium-doped construction of oxygen vacancies in IrO2 to promote acidic OER reaction

Proton exchange membrane electrolysis of water is currently recognized in the world as an up-and-coming method for the preparation of green hydrogen energy. Due to its sustainability and low pollution, it has attracted much attention from practitioners recently. The most advanced iridium oxide (IrO2) is the most promising catalyst.However, developing a highly efficient and stable IrO2 catalyst that can adapt to industrial conditions remains a terrific challenge. One of the main problems to be solved is that the slow oxygen evolution reaction(OER) at the anode limits the production of hydrogen. We propose a straightforward method for synthesizing Ce metal-doped IrO2 with a high oxygen vacancy concentration while simultaneously improving the IrO2 catalytic activity and stability.The Ce-doped IrO2 (Ce-IrO2) exhibits a microscopic nanoparticle morphology and a high density of oxygen vacancies, enabling a rapid oxygen evolution reaction (OER) process with a low overpotential of 240 mV at 10 mA·cm-2 and a remarkable stability of over 50 h under acidic conditions.A growing body of research shows a synergistic effect of oxygen vacancies and mental dopants on the adsorption and evolution of active intermediates in the active center so that the oxygen evolution reaction activity of the Ir-based catalyst can be improved. We hope that ourwork will provide a sample method for acquiring catalysts capable of adapting to a wide range of conditions via metal doping.

Half-metallization Atom-Fingerprints Achieved at Ultrafast Oxygen-Evaporated Pyrochlores for Acidic Water Oxidation.

The stability and catalytic activity of acidic oxygen evolution reaction (OER) are strongly determined by the coordination states and spatial symmetry among metal sites at catalysts. Herein, an ultrafast oxygen evaporation technology to rapidly soften the intrinsic covalent bonds using ultrahigh electrical pulses is suggested, in which prospective charged excited states at this extreme avalanche condition can generate a strong electron-phonon coupling to rapidly evaporate some coordinated oxygen (O) atoms, finally leading to a controllable half-metallization feature. Simultaneously, the relative metal (M) site arrays can be orderly locked to delineate some intriguing atom-fingerprints at pyrochlore catalysts, where the coexistence of metallic bonds (M─M) and covalent bonds (M─O) at this symmetry-breaking configuration can partially restrain crystal field effect to generate a particular high-spin occupied state. This half-metallization catalyst can effectively optimize the spin-related reaction kinetics in acidic OER, giving rise to 10.3 times (at 188mV overpotential) reactive activity than pristine pyrochlores. This work provides a new understanding of half-metallization atom-fingerprints at catalyst surfaces to accelerate acidic water oxidation.

Allosteric stem-loop multicomponent DNAzyme: A versatile stimuli-responsive switch for nanotweezer operations and multifunctional biosensing

DNAzyme, possessing the capabilities of both encoding information and catalyzing chemical reactions, holds significant value in advancing the widespread application of dynamic nanotechnology. Particularly, multicomponent DNAzyme (MNAzyme) has attracted considerable attention due to its remarkable versatility and practicality. However, the inevitable signal leakage of MNAzyme constrains the applications in complex nucleic acid reaction networks. Herein, we present an allosteric stem-loop multicomponent DNAzyme (ASLM) that incorporates a blocking domain to mitigate leakage resulting from secondary structures of MNAzyme while simultaneously stabilizing binding affinity during complex formation. As the sequence of blocking domain serves as an extension independent of the functional region in MNAzyme, this modulation structure can be flexibly assembled with conformation-switchable nanotweezer to form a time-responsive molecular device, enabling dynamic and dissipative operations through nucleic acid and RNase H. More importantly, the ASLM structure can be directly incorporated into DNA catalytic circuits for detecting multiple biomolecules (nucleic acid, protease, and small molecule). With its scalability and versatility, this effector-activated allosteric regulator will serve as a universal stimuli-responsive switch in complex and hierarchical DNA networks, expanding the scope of DNA nanotechnology in molecular device construction and diagnostic biosensing.

Temperature control technology for PCR

AbstractIn order to solve the obvious nonlinear problem of temperature and complex structure of PCR instrument during nucleic acid amplification. In this paper, a new nucleic acid amplification device and temperature control algorithm were proposed. In the device, in order to improve the rise and fall rate and make the whole reaction device smaller and simpler, this paper uses a microfluidic chip for nucleic acid reaction. At the same time, in the warming and cooling module, the temperature is controlled by the semiconductor chilling plate, the air‐cooled cooling device and the heat sink structure, which greatly improves the speed of nucleic acid amplification. In the algorithm, a hybrid algorithm is designed, using Particle Swarm Optimization (PSO) to optimize PID algorithm parameters, and then based on fuzzy theory, according to the temperature control requirements of nucleic acid amplification, fuzzy rules are analyzed and fuzzy reasoning is carried out, and then combined with PID to achieve rapid response and overshooting control of temperature control. Finally, the measurement noise is filtered by Kalman filter. Finally, COMSOL and MATLAB software are used to simulate and compare, and it is proved that the device has a certain heat dissipation effect in the process of nucleic acid amplification. This algorithm can improve the accuracy and robustness of the control system, improve the response speed, reduce the overshoot, shorten the adjustment time, and restrain the interference.

Photoinduced Metal-Free Decarboxylative Fluoroalkylation of Alkenes for the Synthesis of N-Arylbutanamides and Oxindoles.

The visible light-induced decarboxylative cascade reaction of fluoroalkyl carboxylic acids has been achieved for the efficient synthesis of fluorinated compounds. However, most of the transformations rely on noble iridium metal complex. Herein, a visible light-induced metal-free decarboxylative cascade reaction of fluoroalkyl carboxylic acids has been realized. This protocol features simple operation, transition metal, and good functional group tolerance.

Photocatalytic Decarboxylative Fluorination by Quinone-Based Isoreticular Covalent Organic Frameworks.

The strategic incorporation of fluorine atoms into molecules has become a cornerstone of modern pharmaceuticals, agrochemicals, and materials science. Herein, we have developed a covalent organic framework (COF)-based, robust photocatalyst that enables the photofluorodecarboxylation reaction of diverse carboxylic acids, producing alkyl fluorides with remarkable efficiency. The catalytic activity of an anthraquinone-based COF catalyst TpAQ outperforms other structurally analogous β-ketoenamine COFs. Through comprehensive control experiments, photoluminescence, and electrochemical studies, we have elucidated the unique features of the material and the mechanistic pathway. This in-depth understanding has paved the way for optimizing the reaction conditions and achieving high yields of alkyl fluorides. The versatility of this protocol extends to a broad range of aliphatic acids with diverse functional groups and heterocycles. It also enabled the late-stage diversification of anti-inflammatory drugs and steroid derivatives. This opens up exciting possibilities for synthesizing novel pharmaceuticals and functionalized molecules. The methodology was also generalized to other light-mediated decarboxylative halogenation reactions. Furthermore, our method demonstrates scalability under both batch and continuous flow conditions, offering a promising approach for large-scale production. Additionally, the TpAQ catalyst exhibits exceptional durability and can be reused multiple times without significant activity loss (>80% yield after the eighth cycle), making it a sustainable and cost-effective solution. This work lays the foundation for developing efficient and sustainable light-driven synthesis methods using COFs as photocatalysts with potential applications beyond alkyl halide synthesis.

Hexagonal-prismatic metal‒organic cages and metal‒organic polymers based on 1,1'-(5-methyl-1,3-phenylene)bis(1H-imidazole) ligand: Synthesis, structural characterization and magnetic property

A serial of hexagonal-prismatic metal organic cages (MOCs), [Co6(OH)2(HCOO)6(pbim)6(H2O)6]·SO4·2HCOO·8H2O (1·2HCOO·8H2O), [Ni6(OH)2(HCOO)6(pbim)6(H2O)6]·SO4·2HCOO·8H2O (2·HCOO·8H2O), {[Co6(μ3-OH)2(μ-HCOO)6(pbim)6(H2O)6]·ClO4}3+·3HCOO·solvent (3·3HCOO·solvent) and {[Ni6(μ3-OH)2(μ-HCOO)6(pbim)6(H2O)6]·ClO4}3+·3HCOO·solvent (4·3HCOO·solvent), was constructed from shuttlecock-like C3-symmetric [M3(μ3-OH) (μ-HCOO)3(H2O)3] (M = Co2+ or Ni2+) clusters generated in situ and a clip-like ligand 1,1'-(5-methyl-1,3-phenylene)bis(1H-imidazole) [pbim]. Interestingly, one SO42− or ClO4− anion was encapsulated in each cage of MOCs 1–4 through cooperative O–H⋯O and C–H⋯O hydrogen-bonding interactions. It was also found that those SO42‒-/ClO4−-encapsulated MOCs, especially SO42‒-encapsulated MOC of Ni2+, displayed quite stability in methanol. Notably, when the crystal parent solution of MOC 1 was disturbed or MOC 1 was immersed in its parent solution for a long time, it resulted in the formation of a 2D coordination polymer [Co(pbim)2(H2O)2]·2HCOO (5) with helical architecture. Unexpectedly, a novel 2D coordination polymer [Ni4(pbim)2(CH3O)4(C6H5COO)4]·2H2O (6·2H2O) based on in-situ produced cubane-like [Ni4(μ3-CH3O)4(μ-COO)2] cluster was solvothermally synthesized through the reaction of benzoic acid with relatively stable MOC 2 in DMF. Magnetic studies show that there are antiferromagnetic coupling exchanged by mixed hydroxyl/carboxylate bridges in shuttlecock-like [M3(μ3-OH) (μ-HCOO)3(H2O)3] clusters of 1 and 2 or in cubane-like [Ni4(μ3-CH3O)4(μ-COO)2] cluster of 6. The best fits for their magnetic behaviours gave the following coupling constants: J = −2.05 cm−1 for 1, J = −1.74 cm−1 for 2, and J1 = −2.85 cm−1 and J2 = −4.01 cm−1 for 6.

Persistent Post COVID-19 Endothelial Dysfunction and Oxidative Stress in Women.

The assessment of endothelial dysfunction and free radical homeostasis parameters were performed in 92 women, aged 45 to 69 years, divided into the following groups: women without COVID-19 (unvaccinated, no antibodies, control); women with acute phase of COVID-19 infection (main group, COVID-19+); 12 months post COVID-19+; women with anti-SARS-CoV-2 IgG with no symptoms of COVID-19 in the last 12 months (asymptomatic COVID-19). Compared to the control, patients of the main group had lower glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities, decreased advanced glycation end products (AGEs) level, higher glutathione reductase (GR) activity, and higher glutathione S transferases pi (GSTpi), thiobarbituric acid reactants (TBARs), endothelin (END)-1, and END-2 concentrations (all p ≤ 0.05). The group with asymptomatic COVID-19 had lower 8-OHdG and oxidized glutathione (GSSG) levels, decreased total antioxidant status (TAS), and higher reduced glutathione (GSH) and GSH/GSSG levels (all p ≤ 0.05). In the group COVID-19+, as compared to the group without clinical symptoms, we detected lower GPx and SOD activities, decreased AGEs concentration, a higher TAS, and greater GR activity and GSTpi and TBARs concentrations (all p ≤ 0.05). The high content of lipid peroxidation products 12 months post COVID-19+, despite decrease in ENDs, indicates long-term changes in free radical homeostasis. These data indicate increased levels of lipid peroxidation production contribute, in part, to the development of free radical related pathologies including long-term post COVID syndrome.

O,S,Se-containing Biginelli products based on cyclic β-ketosulfone and their postfunctionalization.

A one-pot three-component Biginelli synthesis of dihydropyrimidinones/thiones/selenones via acetic acid or solvent-free Yb(OTf)3-catalyzed tandem reaction of β-ketosulfone (dihydro-2H-thiopyran-3(4H)-one-1,1-dioxide), an appropriate urea, and arylaldehyde has been developed. The reaction proceeds with high chemo- and regioselectivity to give diverse DHPMs in reasonable yields up to 95%. Moreover, an SO2-containing analogue of anticancer drug-candidate enastron (SO2 vs C=O) was obtained by using the here reported method in gram scale. We also demonstrate the reactivity of the Biginelli product in various directions - synthesis of condensed thiazoles and tetrazoles. In silico assessment of ADMET parameters shows that most compounds meet the lead-likeness requirements. The biological profiles of new compounds demonstrate high probability levels of activity against the following pathogens/diseases: Candida albicans, Alphis gossypii, Tripomastigote Chagas, Tcruzi amastigota, Tcruzi epimastigota, Leishmania amazonensis, and Dengue larvicida.

Synthesis and Characterization of Palladium Catalyzed (Carbon-carbon Bond Formation) compounds

In atmospheric condition, cesium carbonate was dissolved in water in a small bottle. Aryl halides, phenyl boronic acid, tetra butyl ammonium bromide, Bis (tri phenyl phosphine) palladium II chloride catalyst and toluene were taken in another small bottle. The contents of both the small bottles were added in a pressure tube. Heating of reaction mixture was done at 80-900C and then stirred until the reaction completion, which was confirmed by TLC. After this, the reaction mixture was extracted with ethyl acetate and the organic layer was washed with brine solution and then filtered by buckner funnel prepared with celite bed. Sodium sulphate was added to the filtrate, filtered again using cotton bed and silica (60-120 mesh size) was added to the filtrate and evaporated by using rotavapour. Through column chromatography, the crude product obtained was purified using Ethyl acetate/Hexane as mobile phase.Bis (tri phenyl phosphine) palladium II chloride catalyzes the reaction of aryl halides and phenyl boronic acid at 80-900C giving moderate to high yields even when the catalyst quantity used was low.

Study on emulsion-filled gels with oxidation stability: Structure, rheology, and baking applications

Specialty oils and fats play a crucial role in enhancing the texture and flavor of foods. The findings revealed that the emulsion-filled gels containing sinapine exhibited a more uniform and consistent distribution of oil droplets and proteins, with an average particle size that was better aligned across the samples. These emulsion-filled gels also exhibited higher stability, up to 95 % oil binding capacity, 3 N higher hardness and 0.2 mJ higher adhesion compared to proanthocyanidins (PC) and catechins (EC). Additionally, they demonstrated better spread-ability. In terms of the rheological properties of the oleogel prepared with sinapine, the apparent viscosity was high and the thixotropy was good. However, the softness was poor. The groups involved in the binding of various species of polyphenols are essentially identical, and the primary non-covalent driving force in this system is hydrogen bonding along with double bonding. With a thiobarbituric acid reactant (TBARS) value of 4.5 µg/mL, sinapine is more effective at maintaining the stability of emulsion-filled gels. It also enhances the oleogel’s oil-holding capacity and antioxidant capacity. In addition, the cookies with increased levels of SPI and sinapine exhibited greater hardness and were more well-received by the public. This information will help expand the application of polyphenol-modified protein-based emulsion-filled gels in food systems.

Non-Noble-Metal-Based Electrocatalysts for Acidic Oxygen Evolution Reaction: Recent Progress, Challenges, and Perspectives.

The oxygen evolution reaction (OER) plays a pivotal role in diverse renewable energy storage and conversion technologies, including water electrolysis, electrochemical CO2 reduction, nitrogen fixation, and metal-air batteries. Among various water electrolysis techniques, proton exchange membrane (PEM)-based water electrolysis devices offer numerous advantages, including high current densities, exceptional chemical stability, excellent proton conductivity, and high-purity H2. Nevertheless, the prohibitive cost associated with Ir/Ru-based OER electrocatalysts poses a significant barrier to the broad-scale application of PEM-based water splitting. Consequently, it is crucial to advance the development of non-noble metal OER catalysis substance with high acid-activity and stability, thereby fostering their widespread integration into PEM water electrolyzers (PEMWEs). In this review, a comprehensive analysis of the acidic OER mechanism, encompassing the adsorbate evolution mechanism (AEM), lattice oxygen mechanism (LOM) and oxide path mechanism (OPM) is offered. Subsequently, a systematic summary of recently reported noble-metal-free catalysts including transition metal-based, carbon-based and other types of catalysts is provided. Additionally, a comprehensive compilation of in situ/operando characterization techniques is provided, serving as invaluable tools for furnishing experimental evidence to comprehend the catalytic mechanism. Finally, the present challenges and future research directions concerning precious-metal-free acidic OER are comprehensively summarized and discussed in this review.

Solvent-Free Synthesis of HKUST-1 with Abundant Defect Sites and Its Catalytic Performance in the Esterification Reaction of Oleic Acid.

HKUST-1 has received increasing attention because of its potential applications in many fields, such as heterogeneous catalysis, sensors, gas storage, and separation. Herein, we report that HKUST-1 can be facilely prepared by heating a ground mixture of copper nitrate trihydrate and 1,3,5-benzenetricarboxylic acid in an autoclave at 80 °C for 10 h. The data from nitrogen sorption show that the obtained material, named HKUST-1-free, possesses a high BET specific surface area of 1671 m2/g and a pore volume of 0.8 cm3/g. The results from acid-base titration indicate that the number of defect sites in HKUST-1-free is more than that in HKUST-1-solvent prepared by the solvothermal method. As a heterogeneous catalyst, HKUST-1-free gave a high yield (91%) of methyl oleate in the esterification reaction of oleic acid with methanol at room temperature compared to HKUST-1-solvent (70%). Additionally, it is proven that HKUST-1-free is a heterogeneous catalyst and can be reused.

Ultrastable monolithic electrodes with single-atom platinum-oxygen sites for efficient hydrogen evolution in acidic conditions

PtNC single-atom catalysts (SACs) single-atom catalysts (SACs) are promising for acidic hydrogen evolution reaction (HER) but suffer from instability at high current densities, limiting their large-scale application. Herein, PtO bonds are constructed to securely anchor atomically dispersed Pt for single-atom (SA) catalysis, utilizing etched vertical graphene (EVG) nanosheets as monolithic supports (Pt-SAs/EVG). Compared to PtNC, the resultant PtO4 coordination demonstrates improved stability while maintaining significant catalytic activity. When applying this catalyst in the acidic HER, a high turnover frequency (34.6 s−1) is achieved at 70 mV, accompanied by exceptional durability exceeding 100 h at −100 mA cm−2. Theoretical analyses indicate that the PtO bonds confer stability to the Pt atoms, facilitating the efficient adsorption of protons and the subsequent desorption of hydrogen. The prepared Pt-SAs/EVG can also be directly employed as the cathode to afford stable operation at 0.5 A cm−2 in a proton exchange membrane electrolyzer cell. This study offers novel insights into enhancing the performance of SACs for industrial applications in electrocatalysis.

Structure Sensitive Reaction Kinetics of Chiral Molecules on Intrinsically Chiral Surfaces.

Enantiospecific heterogeneous catalysis utilizes chiral surfaces to resolve enantiomers via structure sensitive surface chemistry. The catalyst design challenge is the identification of chiral surface structures that maximize enantiospecificity. Herein, we develop data driven models for the enantiospecificity of tartaric acid reactions on chiral Cu(hkl)R&S surfaces. Measurements of enantiospecific rate constants were obtained by using curved Cu(hkl)R&S surfaces that enable kinetic measurements on hundreds of chiral surface orientations. One model uses feature vectors derived from generalized coordination numbers to capture the local structure around Cu atoms exposed by the Cu(hkl)R&S surfaces. The second model introduces the use of chiral cubic harmonic functions to capture the symmetry constraints of the face-centered cubic Cu structure. The model using 58 generalized coordination numbers has a fitting error similar to that of the model using only 5 cubic harmonic functions. The two models predict maxima in the enantiospecificity on surfaces with very similar surface orientations. The models developed in this work are applicable for any enantiospecific reaction happening on any chiral material with a cubic lattice structure, opening the way to understanding the surface structure sensitivity of the enantiospecific reaction kinetics.

Elucidating the Synergistic Promotional Mechanism of Water and Oxygen in the Aerobic C-C Homocoupling Reaction Catalyzed by Visible-Light-Derived Core-Shell Pd@A-CQDs Nanostructures.

Rational design and precise synthesis of biogenic noble-metal-based catalysts possessing distinctive structure and composition play a crucial role in the chemical industry, enabling sustainable construction of an inclusive range of chemical resources. In this study, we have effectively fabricated Pd@A-CQDs through a straightforward one-pot aqueous protocol assisted by visible light employing renewable biomass-derived amine-rich carbon quantum dots (A-CQDs). The remarkable visible light harnessing capability (bandgap, ca. 2.81 eV), high density (35.7 × 1018 cm-3), and long lifetime (25 ps) of photocharge carriers and amine-rich surface in A-CQDs make them ideal candidates as both reducing and stabilizing agents, thereby facilitating the in situ construction of metallic Pd(0) nanoparticles. Comprehensive physicochemical characterizations have provided compelling evidence for the spherical morphology of Pd@A-CQDs core-shell nanostructures, with ultrathin A-CQDs shells of ca. 1.9 nm and an average diameter of 14 ± 1 nm. The effectiveness of the synthesized Pd@A-CQDs catalysts was assessed in the ligand- and base-free homocoupling reaction of arylboronic acids in water at ambient temperature. The catalytic tests demonstrated the selective production of the homocoupled compound over protodeboronation products with excellent yield and high catalyst recyclability under ambient conditions. The protocol employed exhibited a high TOF (1.05 × 10-2 mol g-1 min-1) and a low E-factor, with a remarkably low palladium loading. XPS analysis confirmed the retention of the metallic nature of the palladium core within the catalysts during the reaction. The catalytic function of the palladium core in conjunction with the A-CQDs shell, along with the promotional effects provided by water and oxygen for the formation of nucleophilic tetravalent boron, was conclusively recognized by 11B NMR and O2-TPD measurements. The obtained experimental results deliver valuable insights into the probable reaction pathway for the homocoupling reaction catalyzed by the Pd@A-CQDs catalysts. Through a comprehensive and sustainable evaluation, the current methodology exhibits superior performance compared to previously documented techniques in relation to estimated circularity and adherence to good manufacturing practices (GMP).

Surface‐Segregated IrCo Nanoparticles on CoO Nanosheets with Ultralow Ir Loading for Efficient Acidic Water Splitting

AbstractIrO2 is the benchmark catalyst for acidic oxygen evolution reaction (OER), however, the high cost and low earth abundance hinder its large‐scale application. Herein, surface‐segregated IrCo nanoparticles on CoO nanosheets with a strong electronic interaction are synthesized through the ion exchange‐pyrolysis method. The resulting IrCo−CoO heterostructures, containing an ultra‐low Ir content of 4.73 wt %, demonstrate exceptional performance in the acidic OER. The catalyst exhibits a low overpotential of 270 mV at a current density of 10 mA cm−2 and remarkable stability, with noticeable activity decay observed only after 140 hours of continuous operation. These results surpass most reported Ir‐based electrocatalysts. Specifically, the mass activity at the overpotential of 300 mV for the IrCo−CoO catalyst reaches 124.52 mA mgIr−1, which is 20 times higher than that of commercial IrO2. Furthermore, we constructed a home‐made overall water splitting cell utilizing IrCo−CoO heterostructures as both anode and cathode electrodes, achieving a current density of 10 mA cm‐−2 at a voltage of 1.51 V. Our findings present a promising strategy for designing high‐efficient catalysts with significantly reduced noble metals loading.

Palladium-Catalyzed Trifluoroacetylation of Arylboronic Acids Using a Trifluoroacetylation Reagent.

A new trifluoroacetylation reagent was developed by using inexpensive and readily available trifluoroacetic anhydride and N-phenyl-4-methylbenzenesulfonamide for the first time. The reaction of (het)aryl boronic acids with the new trifluoroacetylation reagent, N-phenyl-N-tosyltrifluoroacetamide, proceeded smoothly in the presence of a palladium catalyst to provide trifluoromethyl ketones in satisfactory to excellent yields. Various groups, including the synthetically useful functional groups Cl, TMS, and PhCO, were tolerated well under the current reaction conditions. This new trifluoroacetylation reagent can be used in the large-scale synthesis of trifluoromethyl ketones, even at a low palladium catalyst loading.

Micromechanism of the effect of coal functional groups on the catalytic/esterification reaction of acetic acid

Acidification modification has proven to be a successful approach for enhancing the permeability of low-permeability coal seams and increasing coalbed methane extraction. To explore the influence of acetic acid on the organic structure of coal, a combined approach of experimental research and quantum chemical calculation is employed to examine the reaction mechanism of coal organic structure in response to acetic acid. Fourier transform infrared spectroscopy reveals a reduction in the content of hydroxyl and C–O bonds in the treated samples, along with the appearance of an absorption peak of C=C bonds. This demonstrates that the main site of acetic acid acidification modification on coal molecules is the hydroxyl functional group. Therefore, glycerol can be used as a simplified model of coal molecules for further investigation. In addition, three typical functional groups (phenyl, hydroxyl, amino) are selected as the research objects. The electronic density topological properties, molecular surface electrostatic potential, Mayer bond orders and CM5 charge of coal molecules were calculated based on quantum chemical theory. This reveals the intrinsic strength of each chemical bond between single atoms in a molecule, thereby predicting potential reaction pathways between acetic acid and coal molecules. The micro-mechanism of acetic acid catalyzing/esterifying the organic structure of coal is studied using transition state methods. The computational results show that there are two main modes of reaction between acetic acid and coal molecules: (1) acetic acid catalyzes the dehydration reaction of coal molecules; (2) acetic acid reacts with coal molecules to form ester intermediates, followed by decomposition through various reactions. Among the 14 reaction pathways, acetic acid provides protons or groups to trigger the dehydration of coal molecules. Interestingly, it is found that the overall hydroxyl group participates in the reaction is easier than the individual hydrogen atom on the hydroxyl group, and the overall carboxyl group participates in the reaction is easier than the individual hydroxyl group. This indicates that the higher the overall atomic reactivity of acetic acid, the lower the reaction barrier. Compared with catalytic reactions, acetic acid tends to undergo esterification reactions with hydroxyl groups, with the phenyl ring functional group significantly affecting the reaction barrier. The introduction of various oxygen-containing functional groups like ketone, aldehyde, and ester in the reaction products will hinder the adsorption of non-polar methane, reduce the adsorption capacity of coal seams for gas, and play an essential role in promoting gas desorption. The research findings can provide theoretical guidance for the organic acidification modification of low-permeability coal seams to enhance gas permeability and coalbed methane extraction.