A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones w...A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.展开更多
LiNi0.8Co0.1Mn0.1O2 cathode was synthesized using transition metal acetates under different synthesis conditions. Simultaneous thermogravimetric–differential scanning calorimetry–derivative thermogravimetric analysi...LiNi0.8Co0.1Mn0.1O2 cathode was synthesized using transition metal acetates under different synthesis conditions. Simultaneous thermogravimetric–differential scanning calorimetry–derivative thermogravimetric analysis was applied to investigating the mixture of transition metal acetates. X-ray powder diffraction and charge–discharge test were adopted to characterize the as-prepared LiNi0.8Co0.1Mn0.1O2. The mixture of transition metal acetates undergoes dehydration and decomposition during heating. All the examined LiNi0.8Co0.1Mn0.1O2 samples have a layered structure with R3 m space group. LiNi0.8Co0.1Mn0.1O2 samples prepared with different lithium sources under different synthesis conditions exhibit very different charge–discharge performances. The sample synthesized via the procedure of sintering at 800 °C after heating lithium carbonate and transition metal acetates at 550 °C achieves a highest capacity of 200.8 m A·h/g and an average capacity of 188.1 mA ·h/g in the first 20 cycles at 0.2C.展开更多
The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column...The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column) for 20 new α\|branched phenylsulfonyl acetates. The atomic charge method was applied to develop quantitative structure retention relationships(QSRRs). Among the available geometric and electronic descriptors, surface area (S), ovality (O), and the charge of carboxyl group(Q OC ) are significant. In the model, the contribution of surface area (S) is the greatest. The molecular mechanism of retention was demonstrated through the model. With the correlation coefficient ( r 2 adj , adjusted for degrees of freedom) of 0.964, the standard error of 0.164 and the F value of 170.39, the model has good predictive capacity.展开更多
Semicarbazones, 1,1-diacetates and acetals are efficiently converted to their corresponding carbonyl compounds using synergistic effect between KBrO3 and MoO3 in refluxing CH3CN-H2O in good to high yields.
A method for locating double bond in hexadecenyl acetates has been developed by analyzing the mass spectral patterns on a fuzzy classification. The procedure was tested with the spectra of Δ~2- to Δ^(15)-isomers and...A method for locating double bond in hexadecenyl acetates has been developed by analyzing the mass spectral patterns on a fuzzy classification. The procedure was tested with the spectra of Δ~2- to Δ^(15)-isomers and the original double-bond position in these acetates was located unambiguously.展开更多
A mild and efficient method for diacetylation reaction was developed,by which diacetate could be achieved through the reaction of aldehyde with acetic anhydride,in the presence of cobalt sulfate,with an admirable yiel...A mild and efficient method for diacetylation reaction was developed,by which diacetate could be achieved through the reaction of aldehyde with acetic anhydride,in the presence of cobalt sulfate,with an admirable yield,at room temperature,without solvent.The catalyst could be recycled six times without a distinct loss of activity.展开更多
Before proposing an innovative process for the coproduction of ethyl and butyl acetates, the individual syntheses of ethyl acetate and butyl acetate by two different routes were first studied. These syntheses involved...Before proposing an innovative process for the coproduction of ethyl and butyl acetates, the individual syntheses of ethyl acetate and butyl acetate by two different routes were first studied. These syntheses involved the reaction of ethanol or n-butanol with acetic acid or acetic anhydride in the presence of ion exchange resins: Amberlyst 15, Amberlyst 16, Amberlyst 36 and Dowex 50WX8. Kinetic and thermodynamic studies were performed with all resins. The lowest activation energy (Ea) value was obtained with Dowex 50WX8, which was identified as the best-performing resin, able to be reused at least in four runs without regeneration. The presence of water-azeotropes during the synthesis of ethyl acetate makes its purification difficult. A new strategy was adopted here, involving the use of ethanol and acetic anhydride as the starting material. In order to minimize acetic acid as co-product of this reaction, a novel two-step process for the coproduction of ethyl and butyl acetates was developed. The first step involves the production of ethyl acetate and its purification. Butyl acetate was produced in the second step: n-butanol was added to the mixture of acetic acid and the resin remaining after the first-step distillation. This process yields ethyl acetate and butyl acetate at high purity and shows an environmental benefit over the independent syntheses by green metrics calculation and life cycle assessment.展开更多
Skin injury repair is a complicated process that involves wound healing.Effective wound dressings play a crucial role in enhancing this process by providing multiple functions,such as wettability,antibacterial activit...Skin injury repair is a complicated process that involves wound healing.Effective wound dressings play a crucial role in enhancing this process by providing multiple functions,such as wettability,antibacterial activity,and drug release.In this study,Calophyllum inophyllum oil(CIO)is incorporated into polyethylene oxide-polyvinyl acetate(PEO-PVAc)nanofibers using an electrospinning technique.The successful incorporation is verified by Fourier-transform infrared spectroscopy,while the morphology is observed by scanning electron microscopy.The fabricated nanofibers are beadless and have fiber diameter distributions of 333–472 nm.The addition of CIO significantly improves the wettability of the nanofibers,as indicated by a decrease in water contact angle,which is crucial for accelerating the healing process.Additionally,the CIO exhibits potent antibacterial activity against both Gram-positive(Escherichia coli)and Gram-negative(Staphylococcus aureus)bacteria,with expanding inhibition zones as the CIO concentration is increased.These findings highlight the great potential of PEO-PVAc/CIO nanofibers for advanced wound healing applications.展开更多
Efficiency of C-C bond coupling in highly inert CO_(2)is relatively low,which severely limits its efficient conversion to acetate.Here,we successfully developed a highly stable NF@CoMn_(2)O_(4)@Cu_(2)O-Ag bimetallic a...Efficiency of C-C bond coupling in highly inert CO_(2)is relatively low,which severely limits its efficient conversion to acetate.Here,we successfully developed a highly stable NF@CoMn_(2)O_(4)@Cu_(2)O-Ag bimetallic active site catalyst by anchoring Ag on the Cu_(2)O surface.In this catalyst,the Co^(3+)/Mn^(3+)-Mn^(4+)removes excess electrons from the Cu+sites via strong electronic interactions,preventing the reduction of Cu_(2)O to metallic Cu^(0),which ensures the NF@CoMn_(2)O_(4)@Cu_(2)O-Ag exhibits a high resistance to deactivation.The Cu+active sites of NF@CoMn_(2)O_(4)@Cu_(2)O-Ag efficiently electroreduce CO_(2)to the*COatop intermediate,while the Ag active sites efficiently electroreduce CO_(2)to the^(*)CO_(bridge)intermediate.The proximity of Cu+/Ag bimetallic sites shortens the distance for C-C bond coupling between the*COatop and^(*)CO_(bridge)intermediates,facilitating the efficient electrocatalytic coupling of CO_(2)to synthesize acetate.DFT analysis indicates that theΔG required for C-C bond coupling on the short-distance Cu+/Ag bimetallic sites of NF@CoMn_(2)O_(4)@Cu_(2)O-Ag is significantly lower than that of NF@CoMn_(2)O_(4)@Cu_(2)O,enabling a high Faradaic efficiency of 64.97%for acetate production at-0.3 V vs.RHE.This study provides an effective strategy for the rational design of synergistic catalysis between heterometallic catalytic sites to efficiently achieve C-C coupling for the synthesis of C2+products.展开更多
In order to address the evolving emission characteristics of oxygenated volatile organic compounds(OVOCs),it is essential to develop adsorbent materials specifically designed for the efficient adsorption of OVOCs with...In order to address the evolving emission characteristics of oxygenated volatile organic compounds(OVOCs),it is essential to develop adsorbent materials specifically designed for the efficient adsorption of OVOCs with large kinetic diameters.In this study,we used co-pyrolysis to prepare a series of graded porous carbon materials with well-developed micropores by adjusting the doping ratios of root nodules and pretreated cellulose.The material with root nodule to cellulose mass ratio of 1:1(TCC-RN-1)exhibited the highest saturated adsorption capacity for butyl acetate(834 mg/g).This can be attributed to enhanced pore size distribution from nodule doping,which facilitates the development of a micropore-graded structure.Additionally,the nodules acted as auxiliary activating agents that enhanced the KOH micropore regulation effect during the activation stage,resulting in the highest micropore volume(0.863 cm^(3)/g).The doping of root nodules facilitated the formation of additional defects on the surface of the porous carbon material,leading to a more disordered arrangement that improved pollutant adsorption.Furthermore,TCC-RN-1 demonstrated good thermal stability in an air atmosphere,main-taining a butyl acetate adsorption capacity exceeding 95%after five adsorption-desorption cycles.This indicates its favorable potential for industrial applications.展开更多
Photothermal synergistic catalytic systems for treating volatile organic compounds(VOCs)have attracted signif-icant attention due to their energy efficiency and potential to reduce carbon emissions.However,the mechani...Photothermal synergistic catalytic systems for treating volatile organic compounds(VOCs)have attracted signif-icant attention due to their energy efficiency and potential to reduce carbon emissions.However,the mechanism underlying the synergistic reaction remains a critical issue.This study introduces a photothermal synergistic system for the removal of ethyl acetate(EA)by synthesizing Cu-doped OMS-2(denoted as Cu-OMS-2).Under ultraviolet-visible(UV–Vis)irradiation in a flow system,the Cu-OMS-2 catalyst exhibited significantly enhanced performance in the EA degradation process,nearly doubling the effectiveness of pure OMS-2,and increasing carbon dioxide yield by 20%.This exceptional performance is attributed to the synergistic effect of increased oxygen vacancies(OV)at OMS-2 active sites and Cu doping,as confirmed by H2-TPR,O_(2)-TPD,and CO consump-tion measurements.This study clarifies the catalytic mechanism of light-assisted thermocatalysis and offers a novel strategy for designing photothermal catalysts with homogeneous Cu-doped nanorods for VOC removal.展开更多
As the core of cathode materials,sensitive metals play important roles in the optimization of acetate production from carbon dioxide(CO_(2))in microbial electrochemical system(MES).In this work,iron(Fe),copper(Cu),and...As the core of cathode materials,sensitive metals play important roles in the optimization of acetate production from carbon dioxide(CO_(2))in microbial electrochemical system(MES).In this work,iron(Fe),copper(Cu),and nickel(Ni)as sensitive metal cathode materials were evaluated for CO_(2) conversion in MES.The MES with Feelectrode as a promising electrode material demonstrated a superior CO_(2) reduction performance with a maximum acetate accumulation of 417.9±39.2 mg/L,which was 1.5 and 1.7 folds higher than that in the Ni-electrode and Cu-electrode groups,respectively.Furthermore,an outstanding electron recovery efficiency of 67.7%was shown in the Fe-electrode group.The electron transfer between electrode-suspended sludge was systematically cross-evaluated by the electrochemical behavior and extracellular polymeric substances.The Fe-electrode group had the highest electron transfer rate with 0.194 s-1(k_(app)),which was 17.6 and 21.5 times higher than that of the Cu-and Ni-electrode groups,respectively.Fe-electrode was beneficial for reducing electrochemical impedance between the electrode and suspended sludge.Additionally,redox substances in extracellular polymeric substances of the Fe-electrode group were increased,implying more favorable electron transport dynamics.Simultaneously,enrichments of functional bacteria Acetoanerobium and increased key enzymes involved in the carbonyl pathway of the Fe-electrode group were observed,which also promoted CO_(2) conversion in MES.This study provides a perspective on evaluating the promising sensitive metal electrode material for the process of CO_(2) valorization in MES and offers a reference for the subsequent electrode modification.展开更多
Studies have shown that chitosan protects against neurodegenerative diseases. However, the precise mechanism remains poorly understood. In this study, we administered chitosan intragastrically to an MPTP-induced mouse...Studies have shown that chitosan protects against neurodegenerative diseases. However, the precise mechanism remains poorly understood. In this study, we administered chitosan intragastrically to an MPTP-induced mouse model of Parkinson's disease and found that it effectively reduced dopamine neuron injury, neurotransmitter dopamine release, and motor symptoms. These neuroprotective effects of chitosan were related to bacterial metabolites, specifically shortchain fatty acids, and chitosan administration altered intestinal microbial diversity and decreased short-chain fatty acid production in the gut. Furthermore, chitosan effectively reduced damage to the intestinal barrier and the blood–brain barrier. Finally, we demonstrated that chitosan improved intestinal barrier function and alleviated inflammation in both the peripheral nervous system and the central nervous system by reducing acetate levels. Based on these findings, we suggest a molecular mechanism by which chitosan decreases inflammation through reducing acetate levels and repairing the intestinal and blood–brain barriers, thereby alleviating symptoms of Parkinson's disease.展开更多
An iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates is described.This strategy employs amidines as CN units and provides a new protocol for the construction of 2,4,6-trisubstituted py...An iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates is described.This strategy employs amidines as CN units and provides a new protocol for the construction of 2,4,6-trisubstituted pyrimidines under batch and continuous flow conditions in moderate to good yields,exhibiting good functional group tolerance,scalability and operational simplicity.展开更多
This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different d...This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different degrees of substitution (DS) were prepared by the reaction of yam starch with glacial acetic acid/acetic anhydride using sulfuric acid as the catalyst. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm?1 in the Fourier transform infrared (FT-IR) spectra. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the starch acetates are more thermally stable than the native starch. The starch esters showed 50% weight loss at temperatures from 328°C to 372°C, while the native starch underwent 50% weight loss at 325°C. The glass transition temperature (T g) of the starch decreased from 273°C to 226°c. The X-ray diffraction (XRD) patterns could be classified as typical of the C-type for yam starch. X-ray diffraction also showed the loss of the ordered C-type starch crystalline structure and the degree of crystallinity of starch decreased from 36.10% to 10.96% with the increasing DS. The scanning electron microscopy (SEM) suggested that the most of the starch granules disintegrated with many visible fragments with the increasing DS.展开更多
ZrOCl2 was found to be an effective Lewis acid catalyst for the solventless chemoselective conversion of aldehydes into geminal-diacetates in high yields at room temperature. Regeneration of the aldehydes from the ace...ZrOCl2 was found to be an effective Lewis acid catalyst for the solventless chemoselective conversion of aldehydes into geminal-diacetates in high yields at room temperature. Regeneration of the aldehydes from the acetals was also achieved using the same catalyst in water. The beneficial effect of microwave irradiation on the reaction was also described. Other advantages are the very low loading of catalyst, high yields achieved even on a gram scale, and considerably shortened reaction time compared to the conventional method.展开更多
The enantioselective allylic amination of Morita-Baylis-Hillman acetates catalyzed by chiral cyclohexane-based thiourea-phosphine catalysts was investigated. In the presence of 20 mol% rosin-derived thiourea-phosphine...The enantioselective allylic amination of Morita-Baylis-Hillman acetates catalyzed by chiral cyclohexane-based thiourea-phosphine catalysts was investigated. In the presence of 20 mol% rosin-derived thiourea-phosphine 3j, the chiral amines were obtained in up to 88% yield and up to 85% ee.展开更多
High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polym...High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.展开更多
Developing favorable bio-based polymers that replace petroleum-based plastics is an essential environmental demand.Lignin is a by-product of the chemical pulping industry.It is a natural UV protection ingredient in br...Developing favorable bio-based polymers that replace petroleum-based plastics is an essential environmental demand.Lignin is a by-product of the chemical pulping industry.It is a natural UV protection ingredient in broad-spectrum(UVA and UVB)sunscreens.It could be partially and selectively acetylated in a simple,fast,and more reliable process.In this work,a composite film was prepared with UV-resistant properties through a casting method.Bio-based cellulose acetate(CA)was employed as a major matrix while nano-acetylated kraft lignin(AL-NPs)was used as filler during synthesizing UV-shielding films loaded with various amounts(1–5 wt.%)of AL-NPs.Kraft lignin was acetylated through a simple and fast microwave-assisted process using acetic acid as a solvent and acetylating agent.The physicochemical and morphological characteristics of the prepared films were evaluated using different methods,including scanning electron microscopy(SEM),Fourier Transform Infrared Spectroscopy(FTIR),X-ray diffraction analysis(XRD),mechanical testing and contact angle measurement.The UV-Vis spectroscopy optical investigation of the prepared films revealed that AL-NPs in the CA matrix showed strong UV absorption.This feature demonstrated the effectiveness of our research in developing UV-resistant bio-based polymer films.Hence,the prepared films can be considered as successful candidates to be applied in packaging applications.展开更多
Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of meth...Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of methyl iodide and humidity interference are two major issues of the vacuum ultraviolet(VUV)lamp initiated CIMS for on-line gaseous formic and acetic acids analysis.In this work,we present a new CIMS based on VUV lamp,and the ion-molecular reactor is separated into photoionization and chemical ionization zones by a reducer electrode.Acetone was added to the photoionization zone,and the VUV photoionization acetone provided low-energy electrons for methyl iodide to generate I−,and the addition of acetone reduced the amount of methyl iodide by 2/3.In the chemical ionization zone,a headspace vial containing ultrapure water was added for humidity calibration,and the vial changes the sensitivity as a function of humidity from ambiguity to well linear correlation(R2>0.95).With humidity calibration,the CIMS can quantitatively measure formic and acetic acids in the humidity range of 0%-88%RH.In this mode,limits of detection of 10 and 50 pptv are obtained for formic and acetic acids,respectively.And the relative standard deviation(RSD)of quantitation stability for 6 days were less than 10.5%.This CIMS was successfully used to determine the formic and acetic acids in the underground parking and ambient environment of the Shandong University campus(Qingdao,China).In addition,we developed a simple model based formic acid concentration to assess vehicular emissions.展开更多
文摘A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.
基金Project(2010ZC051)supported by the Natural Science Foundation of Yunnan Province,ChinaProject(20140439)supported by the Analysis and Testing Foundation from Kunming University of Science and Technology,ChinaProject(14118245)supported by the Starting Research Fund from Kunming University of Science and Technology,China
文摘LiNi0.8Co0.1Mn0.1O2 cathode was synthesized using transition metal acetates under different synthesis conditions. Simultaneous thermogravimetric–differential scanning calorimetry–derivative thermogravimetric analysis was applied to investigating the mixture of transition metal acetates. X-ray powder diffraction and charge–discharge test were adopted to characterize the as-prepared LiNi0.8Co0.1Mn0.1O2. The mixture of transition metal acetates undergoes dehydration and decomposition during heating. All the examined LiNi0.8Co0.1Mn0.1O2 samples have a layered structure with R3 m space group. LiNi0.8Co0.1Mn0.1O2 samples prepared with different lithium sources under different synthesis conditions exhibit very different charge–discharge performances. The sample synthesized via the procedure of sintering at 800 °C after heating lithium carbonate and transition metal acetates at 550 °C achieves a highest capacity of 200.8 m A·h/g and an average capacity of 188.1 mA ·h/g in the first 20 cycles at 0.2C.
基金TheNationalNaturalScienceFoundationofChina (No .2 9837180 )
文摘The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column) for 20 new α\|branched phenylsulfonyl acetates. The atomic charge method was applied to develop quantitative structure retention relationships(QSRRs). Among the available geometric and electronic descriptors, surface area (S), ovality (O), and the charge of carboxyl group(Q OC ) are significant. In the model, the contribution of surface area (S) is the greatest. The molecular mechanism of retention was demonstrated through the model. With the correlation coefficient ( r 2 adj , adjusted for degrees of freedom) of 0.964, the standard error of 0.164 and the F value of 170.39, the model has good predictive capacity.
基金The partial support of this work by the University of Guilan Research Council is gratefully acknowledged.
文摘Semicarbazones, 1,1-diacetates and acetals are efficiently converted to their corresponding carbonyl compounds using synergistic effect between KBrO3 and MoO3 in refluxing CH3CN-H2O in good to high yields.
文摘A method for locating double bond in hexadecenyl acetates has been developed by analyzing the mass spectral patterns on a fuzzy classification. The procedure was tested with the spectra of Δ~2- to Δ^(15)-isomers and the original double-bond position in these acetates was located unambiguously.
文摘A mild and efficient method for diacetylation reaction was developed,by which diacetate could be achieved through the reaction of aldehyde with acetic anhydride,in the presence of cobalt sulfate,with an admirable yield,at room temperature,without solvent.The catalyst could be recycled six times without a distinct loss of activity.
基金supported by the European Union’s Seventh Framework Program for research,technological development and demonstration(FP7/2007-2013)[Grant Agreement No.605215]CONACyT for providing funding through PhD scholarship no.383910.
文摘Before proposing an innovative process for the coproduction of ethyl and butyl acetates, the individual syntheses of ethyl acetate and butyl acetate by two different routes were first studied. These syntheses involved the reaction of ethanol or n-butanol with acetic acid or acetic anhydride in the presence of ion exchange resins: Amberlyst 15, Amberlyst 16, Amberlyst 36 and Dowex 50WX8. Kinetic and thermodynamic studies were performed with all resins. The lowest activation energy (Ea) value was obtained with Dowex 50WX8, which was identified as the best-performing resin, able to be reused at least in four runs without regeneration. The presence of water-azeotropes during the synthesis of ethyl acetate makes its purification difficult. A new strategy was adopted here, involving the use of ethanol and acetic anhydride as the starting material. In order to minimize acetic acid as co-product of this reaction, a novel two-step process for the coproduction of ethyl and butyl acetates was developed. The first step involves the production of ethyl acetate and its purification. Butyl acetate was produced in the second step: n-butanol was added to the mixture of acetic acid and the resin remaining after the first-step distillation. This process yields ethyl acetate and butyl acetate at high purity and shows an environmental benefit over the independent syntheses by green metrics calculation and life cycle assessment.
基金funded by Rekognisi Tugas Akhir(RTA)program(Contract No.5286/UN1.P1/PT.01.03/2024)supported by Universitas Gadjah Mada,Indonesia.
文摘Skin injury repair is a complicated process that involves wound healing.Effective wound dressings play a crucial role in enhancing this process by providing multiple functions,such as wettability,antibacterial activity,and drug release.In this study,Calophyllum inophyllum oil(CIO)is incorporated into polyethylene oxide-polyvinyl acetate(PEO-PVAc)nanofibers using an electrospinning technique.The successful incorporation is verified by Fourier-transform infrared spectroscopy,while the morphology is observed by scanning electron microscopy.The fabricated nanofibers are beadless and have fiber diameter distributions of 333–472 nm.The addition of CIO significantly improves the wettability of the nanofibers,as indicated by a decrease in water contact angle,which is crucial for accelerating the healing process.Additionally,the CIO exhibits potent antibacterial activity against both Gram-positive(Escherichia coli)and Gram-negative(Staphylococcus aureus)bacteria,with expanding inhibition zones as the CIO concentration is increased.These findings highlight the great potential of PEO-PVAc/CIO nanofibers for advanced wound healing applications.
文摘Efficiency of C-C bond coupling in highly inert CO_(2)is relatively low,which severely limits its efficient conversion to acetate.Here,we successfully developed a highly stable NF@CoMn_(2)O_(4)@Cu_(2)O-Ag bimetallic active site catalyst by anchoring Ag on the Cu_(2)O surface.In this catalyst,the Co^(3+)/Mn^(3+)-Mn^(4+)removes excess electrons from the Cu+sites via strong electronic interactions,preventing the reduction of Cu_(2)O to metallic Cu^(0),which ensures the NF@CoMn_(2)O_(4)@Cu_(2)O-Ag exhibits a high resistance to deactivation.The Cu+active sites of NF@CoMn_(2)O_(4)@Cu_(2)O-Ag efficiently electroreduce CO_(2)to the*COatop intermediate,while the Ag active sites efficiently electroreduce CO_(2)to the^(*)CO_(bridge)intermediate.The proximity of Cu+/Ag bimetallic sites shortens the distance for C-C bond coupling between the*COatop and^(*)CO_(bridge)intermediates,facilitating the efficient electrocatalytic coupling of CO_(2)to synthesize acetate.DFT analysis indicates that theΔG required for C-C bond coupling on the short-distance Cu+/Ag bimetallic sites of NF@CoMn_(2)O_(4)@Cu_(2)O-Ag is significantly lower than that of NF@CoMn_(2)O_(4)@Cu_(2)O,enabling a high Faradaic efficiency of 64.97%for acetate production at-0.3 V vs.RHE.This study provides an effective strategy for the rational design of synergistic catalysis between heterometallic catalytic sites to efficiently achieve C-C coupling for the synthesis of C2+products.
基金supported by the National Natural Science Foundation of China(No.52370112).
文摘In order to address the evolving emission characteristics of oxygenated volatile organic compounds(OVOCs),it is essential to develop adsorbent materials specifically designed for the efficient adsorption of OVOCs with large kinetic diameters.In this study,we used co-pyrolysis to prepare a series of graded porous carbon materials with well-developed micropores by adjusting the doping ratios of root nodules and pretreated cellulose.The material with root nodule to cellulose mass ratio of 1:1(TCC-RN-1)exhibited the highest saturated adsorption capacity for butyl acetate(834 mg/g).This can be attributed to enhanced pore size distribution from nodule doping,which facilitates the development of a micropore-graded structure.Additionally,the nodules acted as auxiliary activating agents that enhanced the KOH micropore regulation effect during the activation stage,resulting in the highest micropore volume(0.863 cm^(3)/g).The doping of root nodules facilitated the formation of additional defects on the surface of the porous carbon material,leading to a more disordered arrangement that improved pollutant adsorption.Furthermore,TCC-RN-1 demonstrated good thermal stability in an air atmosphere,main-taining a butyl acetate adsorption capacity exceeding 95%after five adsorption-desorption cycles.This indicates its favorable potential for industrial applications.
基金supported by the Qilu University of Technology(Shandong Academy of Sciences),the Basic Research Project of Science,Education and Industry Integration Pilot Project(No.2022PY047).
文摘Photothermal synergistic catalytic systems for treating volatile organic compounds(VOCs)have attracted signif-icant attention due to their energy efficiency and potential to reduce carbon emissions.However,the mechanism underlying the synergistic reaction remains a critical issue.This study introduces a photothermal synergistic system for the removal of ethyl acetate(EA)by synthesizing Cu-doped OMS-2(denoted as Cu-OMS-2).Under ultraviolet-visible(UV–Vis)irradiation in a flow system,the Cu-OMS-2 catalyst exhibited significantly enhanced performance in the EA degradation process,nearly doubling the effectiveness of pure OMS-2,and increasing carbon dioxide yield by 20%.This exceptional performance is attributed to the synergistic effect of increased oxygen vacancies(OV)at OMS-2 active sites and Cu doping,as confirmed by H2-TPR,O_(2)-TPD,and CO consump-tion measurements.This study clarifies the catalytic mechanism of light-assisted thermocatalysis and offers a novel strategy for designing photothermal catalysts with homogeneous Cu-doped nanorods for VOC removal.
基金supported by the Science and Technology Commission of Shanghai Municipality Foundation(No.22230710500)the Interdisciplinary joint research project of Tongji University(No.2023-3-YB-07).
文摘As the core of cathode materials,sensitive metals play important roles in the optimization of acetate production from carbon dioxide(CO_(2))in microbial electrochemical system(MES).In this work,iron(Fe),copper(Cu),and nickel(Ni)as sensitive metal cathode materials were evaluated for CO_(2) conversion in MES.The MES with Feelectrode as a promising electrode material demonstrated a superior CO_(2) reduction performance with a maximum acetate accumulation of 417.9±39.2 mg/L,which was 1.5 and 1.7 folds higher than that in the Ni-electrode and Cu-electrode groups,respectively.Furthermore,an outstanding electron recovery efficiency of 67.7%was shown in the Fe-electrode group.The electron transfer between electrode-suspended sludge was systematically cross-evaluated by the electrochemical behavior and extracellular polymeric substances.The Fe-electrode group had the highest electron transfer rate with 0.194 s-1(k_(app)),which was 17.6 and 21.5 times higher than that of the Cu-and Ni-electrode groups,respectively.Fe-electrode was beneficial for reducing electrochemical impedance between the electrode and suspended sludge.Additionally,redox substances in extracellular polymeric substances of the Fe-electrode group were increased,implying more favorable electron transport dynamics.Simultaneously,enrichments of functional bacteria Acetoanerobium and increased key enzymes involved in the carbonyl pathway of the Fe-electrode group were observed,which also promoted CO_(2) conversion in MES.This study provides a perspective on evaluating the promising sensitive metal electrode material for the process of CO_(2) valorization in MES and offers a reference for the subsequent electrode modification.
基金supported by the National Natural Science Foundation of China,Nos. 32260196 (to JY), 81860646 (to ZY) and 31860274 (to JY)a grant from Yunnan Department of Science and Technology,Nos. 202101AT070251 (to JY), 202201AS070084 (to ZY), 202301AY070001-239 (to JY), 202101AZ070001-012, and 2019FI016 (to ZY)。
文摘Studies have shown that chitosan protects against neurodegenerative diseases. However, the precise mechanism remains poorly understood. In this study, we administered chitosan intragastrically to an MPTP-induced mouse model of Parkinson's disease and found that it effectively reduced dopamine neuron injury, neurotransmitter dopamine release, and motor symptoms. These neuroprotective effects of chitosan were related to bacterial metabolites, specifically shortchain fatty acids, and chitosan administration altered intestinal microbial diversity and decreased short-chain fatty acid production in the gut. Furthermore, chitosan effectively reduced damage to the intestinal barrier and the blood–brain barrier. Finally, we demonstrated that chitosan improved intestinal barrier function and alleviated inflammation in both the peripheral nervous system and the central nervous system by reducing acetate levels. Based on these findings, we suggest a molecular mechanism by which chitosan decreases inflammation through reducing acetate levels and repairing the intestinal and blood–brain barriers, thereby alleviating symptoms of Parkinson's disease.
基金the National Natural Science Foundation of China(No.22078150)the National Key R&D Program of China(No.2021YFC2101904)+1 种基金the Jiangsu Province Industrial Prospects and Key Core Technologies-Competitive Projects(No.BE2021083)the Nanjing International Joint R&D Project(No.202002037)for their financial support。
文摘An iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates is described.This strategy employs amidines as CN units and provides a new protocol for the construction of 2,4,6-trisubstituted pyrimidines under batch and continuous flow conditions in moderate to good yields,exhibiting good functional group tolerance,scalability and operational simplicity.
基金the funds for New Century Elite of Education Ministry (Grant No. E105001)the funds from the Tianjin Municipal Science and Technology Commis-sion (Grant No. 07JCZDJC05400)Natural Science Foundation of Tianjin Mu-nicipal (Grant No. 08JCZDJC15300)
文摘This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different degrees of substitution (DS) were prepared by the reaction of yam starch with glacial acetic acid/acetic anhydride using sulfuric acid as the catalyst. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm?1 in the Fourier transform infrared (FT-IR) spectra. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the starch acetates are more thermally stable than the native starch. The starch esters showed 50% weight loss at temperatures from 328°C to 372°C, while the native starch underwent 50% weight loss at 325°C. The glass transition temperature (T g) of the starch decreased from 273°C to 226°c. The X-ray diffraction (XRD) patterns could be classified as typical of the C-type for yam starch. X-ray diffraction also showed the loss of the ordered C-type starch crystalline structure and the degree of crystallinity of starch decreased from 36.10% to 10.96% with the increasing DS. The scanning electron microscopy (SEM) suggested that the most of the starch granules disintegrated with many visible fragments with the increasing DS.
文摘ZrOCl2 was found to be an effective Lewis acid catalyst for the solventless chemoselective conversion of aldehydes into geminal-diacetates in high yields at room temperature. Regeneration of the aldehydes from the acetals was also achieved using the same catalyst in water. The beneficial effect of microwave irradiation on the reaction was also described. Other advantages are the very low loading of catalyst, high yields achieved even on a gram scale, and considerably shortened reaction time compared to the conventional method.
基金We are grateful for the financial support from the National Natural Science Foundation of China （Nos. 21242007, 21102043）, Science and Technology Com- mission of Shanghai Municipality （No. 15ZR1409200）, and the Fundamental Research Funds for the Central Universities.
文摘The enantioselective allylic amination of Morita-Baylis-Hillman acetates catalyzed by chiral cyclohexane-based thiourea-phosphine catalysts was investigated. In the presence of 20 mol% rosin-derived thiourea-phosphine 3j, the chiral amines were obtained in up to 88% yield and up to 85% ee.
文摘High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.
文摘Developing favorable bio-based polymers that replace petroleum-based plastics is an essential environmental demand.Lignin is a by-product of the chemical pulping industry.It is a natural UV protection ingredient in broad-spectrum(UVA and UVB)sunscreens.It could be partially and selectively acetylated in a simple,fast,and more reliable process.In this work,a composite film was prepared with UV-resistant properties through a casting method.Bio-based cellulose acetate(CA)was employed as a major matrix while nano-acetylated kraft lignin(AL-NPs)was used as filler during synthesizing UV-shielding films loaded with various amounts(1–5 wt.%)of AL-NPs.Kraft lignin was acetylated through a simple and fast microwave-assisted process using acetic acid as a solvent and acetylating agent.The physicochemical and morphological characteristics of the prepared films were evaluated using different methods,including scanning electron microscopy(SEM),Fourier Transform Infrared Spectroscopy(FTIR),X-ray diffraction analysis(XRD),mechanical testing and contact angle measurement.The UV-Vis spectroscopy optical investigation of the prepared films revealed that AL-NPs in the CA matrix showed strong UV absorption.This feature demonstrated the effectiveness of our research in developing UV-resistant bio-based polymer films.Hence,the prepared films can be considered as successful candidates to be applied in packaging applications.
基金supported by the National Special Fund for the Development of Major Research Equipment and Instrument(No.2020YFF01014503)the Young Taishan Scholars(No.tsqn201909039)the College 20 Project fromJi Nan Science&Technology Bureau(No.2021GXRC058).
文摘Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of methyl iodide and humidity interference are two major issues of the vacuum ultraviolet(VUV)lamp initiated CIMS for on-line gaseous formic and acetic acids analysis.In this work,we present a new CIMS based on VUV lamp,and the ion-molecular reactor is separated into photoionization and chemical ionization zones by a reducer electrode.Acetone was added to the photoionization zone,and the VUV photoionization acetone provided low-energy electrons for methyl iodide to generate I−,and the addition of acetone reduced the amount of methyl iodide by 2/3.In the chemical ionization zone,a headspace vial containing ultrapure water was added for humidity calibration,and the vial changes the sensitivity as a function of humidity from ambiguity to well linear correlation(R2>0.95).With humidity calibration,the CIMS can quantitatively measure formic and acetic acids in the humidity range of 0%-88%RH.In this mode,limits of detection of 10 and 50 pptv are obtained for formic and acetic acids,respectively.And the relative standard deviation(RSD)of quantitation stability for 6 days were less than 10.5%.This CIMS was successfully used to determine the formic and acetic acids in the underground parking and ambient environment of the Shandong University campus(Qingdao,China).In addition,we developed a simple model based formic acid concentration to assess vehicular emissions.
