Herein,we present a copper-catalyzed carbonylative cross-coupling of unactivated alkyl bromides with aryl boronates under CO atmosphere which enabling the efficient synthesis of C(sp3)-C(sp2)ketones with extensive fun...Herein,we present a copper-catalyzed carbonylative cross-coupling of unactivated alkyl bromides with aryl boronates under CO atmosphere which enabling the efficient synthesis of C(sp3)-C(sp2)ketones with extensive functional group compatibility.This strategy represents a significant advance in copper-catalyzed carbonylation involving alkyl bromides and C(sp2)-nucleophiles.The protocol addresses key challenges commonly encountered in the coupling of C(sp3)-alkyl halides with aryl boron reagents,such as sluggish oxidative addition of alkyl halides,competing Suzuki-Miyaura cross-coupling,undesired dehalogenation and so on.Distinguished by its broad substrate scope and high functional group tolerance,this approach offers a robust and versatile platform for the streamlined synthesis of alkyl aryl ketones.展开更多
Alkali and alkaline‐earth metals from fly ash have a significant deactivation effect on catalysts used for selective catalytic reduction of NOx by NH3(NH3‐SCR).Bromides are considered effective additives to improve ...Alkali and alkaline‐earth metals from fly ash have a significant deactivation effect on catalysts used for selective catalytic reduction of NOx by NH3(NH3‐SCR).Bromides are considered effective additives to improve Hg0 oxidation on SCR catalysts.In this work,the effects of different bromides(NH4Br,NaBr,KBr,and CaBr2)on a commercial V2O5‐WO3/TiO2 catalyst were studied.NOx conversion decreased significantly over the KBr‐poisoned catalyst(denoted as L‐KBr),while that over NaBr‐and CaBr2‐poisoned catalysts(denoted as L‐NaBr and L‐CaBr,respectivity)decreased to a lesser extent compared with the fresh sample.Poor N2 selectivity was observed over L‐NaBr,L‐KBr and L‐CaBr catalysts.The decrease in the ratio of chemisorbed oxygen to total surface oxygen(Oα/(Oα+Oβ+Ow)),reducibility and surface acidity might contribute to the poor activity and N2 selectivity over L‐KBr catalyst.The increased Oαratio was conducive to the enhanced reducibility of L‐CaBr.Combined with enhanced surface acidity,this might offset the negative effect of the loss of active sites by CaBr2 covering.The overoxidation of NH3 and poor N2 selectivity in NH3 oxidation should retard the SCR activity at high temperatures over L‐CaBr catalyst.The increased basicity might contribute to increased NOx adsorption on L‐KBr and L‐CaBr catalysts.A correlation between the acid‐basic and redox properties of bromide‐poisoned catalysts and their catalytic properties is established.展开更多
Highly active, air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents. Suzuki cro...Highly active, air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents. Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid occurred efficiently using palladium phosphinous acid complexes （POPd） and phase transfer catalyst （tetrabutylammonium bromide and polyethylene glycol） in water/ethanol mixture, water/propanol mixture and neat water respectively, the corresponding yields of cross-coupling heteroaryl-aryls were satisfied. The tert-butyl substituted ligand di-tert-butylphosphino in combination with POPd was found to be more active than the same family derived catalysts dipalladium complexes POPdl and POPd2, and other two kinds of Pd-catalysts Pd（PPh3）4 and Pd2（dba）3. The mechanism of Suzuki cross-coupling reaction between heteroaryl bromides and phenylboronic acid in water was proposed with respect to the key role of phase transfer catalyst on the transmetallation step. Compared with other solid phase transfer catalysts, TBAB was tested as the ideal one. The alkalinity of base and the molar proportion between POPd and TBAB were investigated in water and alcoholic solvents. Notably, in the presence of TBAB adding alcoholic solvents into water enhanced the yields of target products. However in terms of the liquid phase transfer catalyst of PEGs, mixing water into PEGs could slightly decrease the yields with respect to the water free PEGs bulk phase, which was probably due to the homogenous liquid conditions in pure PEGs and weak interactions between PEGs and heteroaryl bromide molecules in water depending on their molecular chain lengths.展开更多
A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmissi...A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen adsorption. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid. The recovery of catalyst was simply by magnetic decantation in the presence of a magnet. The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity. No leaching of active palladium species into the reaction solution was detected.展开更多
The catalytic effects for the oxidative methylation of toluene with methane over the basic zeolite catalysts prepared by promoting KY, KX, KM, KZSM-5 or KP with alkali-metal bromides and alkali-metal oxides have been ...The catalytic effects for the oxidative methylation of toluene with methane over the basic zeolite catalysts prepared by promoting KY, KX, KM, KZSM-5 or KP with alkali-metal bromides and alkali-metal oxides have been investigated comparatively. The alkali-metal bromides promoted substrates are more effective than the alkali-metal oxides promoted systems. Moreover, the NaBr promoted systems are more active than KBr promoted systems. The most effective catalytic system (8wt%NaBr)/KZSM-5 gave a toluene conversion as high as 76.3% and a total C-8 selectivity of 76.4% (styrene/ethylbenzene=9.76) resulting in a total C-8 yield of 58.3%.展开更多
The integral heat of solution of REBr 3·3Gly·3H 2O(RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y; Gly is glycine) in water, REBr 3· n H 2O(RE=La, Ce and Pr, n =7; RE=Nd, Sm, Eu, Gd, Tb, Dy and Y, n...The integral heat of solution of REBr 3·3Gly·3H 2O(RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y; Gly is glycine) in water, REBr 3· n H 2O(RE=La, Ce and Pr, n =7; RE=Nd, Sm, Eu, Gd, Tb, Dy and Y, n =6) in aqueous glycine solution and glycine in water have been measured calorimetrically at 298 15±0 15 K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation of REBr 3·3Gly·3H 2O have been obtained and their lattice energies have been calculated.展开更多
A convenient one-pot synthesis of functionalized （E）-2-arylvinyl bromides was achieved by microwave-induced deacetylation and subsequent acylation using dicyclohexyl carbodiimide （DCC） and dimethylamino-pyridine ...A convenient one-pot synthesis of functionalized （E）-2-arylvinyl bromides was achieved by microwave-induced deacetylation and subsequent acylation using dicyclohexyl carbodiimide （DCC） and dimethylamino-pyridine （DMAP） at room temperature from （E）-4-（2-bromovinyl）phenyl acetate.展开更多
A highly efficient and metal-free catalytic system for the synthesis of various selenylated maleimides and alkene derivatives via ammonium bromide-catalyzed direct selenylation of C(sp^(2))—H bond in maleimides and 1...A highly efficient and metal-free catalytic system for the synthesis of various selenylated maleimides and alkene derivatives via ammonium bromide-catalyzed direct selenylation of C(sp^(2))—H bond in maleimides and 1,1-diaryl alkenes using elemental selenium and boronic acids as the selenyl source is developed.Simple catalytic conditions,wide substrate scope,good functional group compatibility,scalable-up,and easy operation are presented in this strategy.The preliminary mechanism reveals that a radical pathway is possibly involved.展开更多
Aiming at the problems of complex process and high cost in the production of potassium bromide at present,the solubility data and the phase diagram of the quaternary system KBr-MgBr_(2)-K_(2)SO_(4)-MgSO_(4)-H_(2)O at ...Aiming at the problems of complex process and high cost in the production of potassium bromide at present,the solubility data and the phase diagram of the quaternary system KBr-MgBr_(2)-K_(2)SO_(4)-MgSO_(4)-H_(2)O at 298.15 K were studied using the isothermal dissolution equilibrium method.The results showed that there are eight invariant points,sixteen univariant curves,and nine crystallization regions in the phase diagram which is complex and contains two double salts(K_(2)SO_(4)·MgSO_(4)·6H_(2)O and KBr·MgBr_(2)·6H_(2)O)and a metastable phase(MgSO_(4)·5H_(2)O).On the basis of the Pitzer model and HW model,the solubilities of the quaternary system were calculated,with which the corresponding phase diagram was plotted.By comparison,the evaluated phase diagram is in accordance with the measured one.Through analysis,the phase diagrams of the quaternary system at(298.15 and 323.15)K were combined to put forward a process to separate KBr from the system by evaporation and crystallization,which realized the full circulation of the mother solution.展开更多
As an important strategic reserve resource,the comprehensive development and utilization of Nanyishan oil-gas field brine will bring great economic and social value.Here,according to the composition characteristics of...As an important strategic reserve resource,the comprehensive development and utilization of Nanyishan oil-gas field brine will bring great economic and social value.Here,according to the composition characteristics of this oil-gas field brine being rich in lithium,potassium and strontium,the solid-liquid stable phase equilibria and phase diagrams of Li-containing quaternary system(LiBr-MgBr_(2)-SrBr_(2)-H_(2)O)and two quinary systems(LiBr-NaBr-MgBr_(2)-SrBr_(2)-H_(2)O and LiBr-KBr-MgBr_(2)-SrBr_(2)-H_(2)O)were studied at 298.15 K.Based on the results of phase equilibrium experimental research,the phase equilibrium relationship and crystallization-dissolution behavior of each component in liquid phase were revealed theoretically,and the changing trend was summarized.Using theoretical model of Pitzer electrolyte solution,the relevant interaction parameters of mixed ions at 298.15 K were obtained by fitting experimental data,and the solubility reaching equilibrium of various salts in above systems was calculated,and the experimental results were verified.The research results of this paper lay an important foundation for further theoretical study of multi-temperature phase equilibrium and thermodynamic properties of complex brine system in the later stage.Meanwhile,it provides basic thermodynamic data and theoretical guidance for the rational development and comprehensive utilization of this oil-gas field brine resources.展开更多
As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the current...As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the currently adopted polyatomic and metal complex anion intercalation process at the graphite electrode in ZnGB exhibits poor electrochemical performances.Alternatively,incorporating halogen anions offers exceptional electrochemical performance to graphite electrodes due to their redox process.In this work,ZnGBs are assembled using a LiCl/ZnCl2/KBr^(-)based water-in-salt electrolyte,which efficiently supplies bromide(Br^(−))ions for conversion into Br_(x)^(−)and facilitates Br_(2)intercalation at the graphite electrode.The conversion and intercalation of bromine together enable the ZnGB to achieve a discharge capacity of 2.73 mAh/cm^(2)with 91.0%of coulombic efficiency(CE)while supporting high current density operations of up to 150 mA/cm^(2).With high energy density(4.56 Wh/cm^(2)),high power density(199.5 mW/cm^(2)),and excellent rate capability(∼93.0%CE at 150 mA/cm^(2)),the ZnGB is shown to operate efficiently for as much as 800 cycles.Beguilingly,an anode-free ZnGB offers enhanced stability for up to 1100 cycles without performance decay,matching the electrochemical performance of Zn metal electrodes.This work provides insights into the bromine reaction mechanism at graphite electrodes and the role of surface exfoliation in enabling efficient Br_(x)^(−)formation,along with Br_(2)intercalation,for achieving high-performance ZnGBs.展开更多
The widespread presence of organophosphate flame retardants(OPFRs)in aquatic environments has raised significant concerns regarding environmental and hu-man health risks.In this study,the adsorption behavior of two re...The widespread presence of organophosphate flame retardants(OPFRs)in aquatic environments has raised significant concerns regarding environmental and hu-man health risks.In this study,the adsorption behavior of two representative aromatic OPFRs,triphenylphosphine ox-ide(TPPO)and triphenyl phosphate(TPhP),was system-atically investigated using organically modified montmoril-lonite(MMT).The effects of various environmental and operational parameters,including cationic surfactant dos-age,temperature,pH,ionic strength,and humic acid(HA)concentration,on OPFR adsorption were thoroughly examined.Results revealed that modification with hexa-decyltrimethylammonium bromide enhanced the TPPO and TPhP adsorption capacities of MMT.The adsorption pro-cess was largely independent of pH and HA concentration,and the presence of inorganic cations significantly improved the adsorption efficiency.Adsorption equilibrium was achieved within 30 min,with kinetics best described by a pseudo-second-order model.The adsorption isotherms ex-hibited a linear relationship,and the distribution coefficients for TPPO and TPhP were 0.16 and 0.51 L/g,respectively.Thermodynamic analysis indicated that the considered ad-sorption was more favorable at lower temperatures.The pri-mary adsorption mechanism was attributed to the partition-ing behavior facilitated by the organophilic nature of the modified MMT.Moreover,the adsorbent demonstrated ex-cellent regeneration performance,with its adsorption capac-ity remaining stable over five consecutive cycles.Overall,these findings show that cationic surfactant-modified MMT has a promising potential for application in wastewater treat-ment to effectively remove OPFRs from aqueous systems.展开更多
The coupling of fast redox kinetics,high-energy density,and prolonged lifespan is a permanent aspiration for aqueous rechargeable zinc batteries,but which has been severely hampered by a narrow voltage range and subop...The coupling of fast redox kinetics,high-energy density,and prolonged lifespan is a permanent aspiration for aqueous rechargeable zinc batteries,but which has been severely hampered by a narrow voltage range and suboptimal compatibility between the electrolytes and electrodes.Here,we unprecedentedly introduced an electric ambipolar effect for synergistic manipulation on Zn^(2+)ternary-hydrated eutectic electrolyte(ZTE)enabling high-performance Zn-Br_(2)batteries.The electric ambipolar effect motivates strong dipole interactions among hydrated perchlorates and bipolar ligands of L-carnitine(L-CN)and sulfamide,which reorganized primary cations solvation sheath in a manner of forming Zn[(L-CN)(SA)(H_(2)O)_(4)]^(2+)configuration and dynamically restricting desolvated H2O molecules,thus ensuring a broadened electrochemical window of 2.9 V coupled with high ionic conductivity.Noticeably,L-CN affords an electrostatic shielding effect and an in situ construction of organic-inorganic interphase,endowing oriented Zn anode plating/stripping reversibly for over 2400 h.Therefore,with the synergy of electro/nucleophilicity and exceptional compatibility,the ZTE electrolyte dynamically boosts the conversion redox of Zn-Br_(2)batteries in terms of high specific capacity and stable cycling performance.These findings open a window for designing electrolytes with synergetic chemical stability and compatibility toward advanced zinc-ion batteries.展开更多
Despite the widespread use of allyl bromides in organic synthesis,the asymmetric transformation of allyl bromides has been less developed.To date,the asymmetric transformation of allyl bromides has been limited to sin...Despite the widespread use of allyl bromides in organic synthesis,the asymmetric transformation of allyl bromides has been less developed.To date,the asymmetric transformation of allyl bromides has been limited to single-site functionalization,and the development of dual-site asymmetric functionalization remains unexplored.In this work,the unprecedented asymmetric dual-site functionalization of allyl bromides has been realized through an efficient organocatalytic system,overcoming the persistent limitation of single-site transformations.Employing dinucleophiles including 3-aminobenzofurans,2-aminoindoles,and cyclohexane-1,3-diones,this methodology affords benzofuro[3,2-b]pyridines andα-carbolines in good yields with excellent stereoselectivity.The transformation proceeds via a chemoselective S_(N)2′pathway mediated by a chiral pyrrolidinyl sulfonamide catalyst,which generates ammonium salts in situ to achieve stereocontrol.The protocol was successfully extended to enantioenriched privileged pyran frameworks,and was applied to diverse downstream transformations.Gram-scale synthesis maintained high enantioselectivity,confirming practical utility.This approach effectively addresses key challenges in efficient construction of complex fused-ring heterocycles,substantially expanding the synthetic applications of allyl bromides.展开更多
The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure wer...The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.展开更多
Functionalized carbon nanotubes （CNTs） were made for the delivery of genes and drugs and CNT-based biosensors. The basis of CNTs is for binding with biomolecules in biomedical applications. The binding tendency with...Functionalized carbon nanotubes （CNTs） were made for the delivery of genes and drugs and CNT-based biosensors. The basis of CNTs is for binding with biomolecules in biomedical applications. The binding tendency with small interfering RNA oligonucleotides and cytotoxicity of cetyltrimethyl ammonium bromide （CTAB）-coated single-walled carbon nanotubes （SWNTs） were studied. The field emission scanning electron microscopy and transmission electron microscopy results show that a SWNT suspension in CTAB solution was well-dispersed and stable. CTAB is the cross-linker between SWNTs and oligonucleotides. The CTAB-coated SWNTs have less cytotoxicity to human umbilical vein endothelial cells than single SWNTs and the cytotoxicity of CTAB-coated SWNTs depended on the concentration of CTAB-coated SWNTs.展开更多
Covalent triazine-based frameworks（CTFs） are important microporous materials with a wide range of applications.Here,we demonstrate an environmentally benign and economic synthetic pathway to CTFs.The monomers used f...Covalent triazine-based frameworks（CTFs） are important microporous materials with a wide range of applications.Here,we demonstrate an environmentally benign and economic synthetic pathway to CTFs.The monomers used for CTFs,aromatic nitriles,were obtained by cyanation using nontoxic potassium hexacyanoferrate（Ⅱ） in place of commonly used toxic cyanides.Then,the CTFs were synthesized by trimerization of the corresponding cyano monomers in molten zinc chloride.A series of CTFs was synthesized,and the highest Brunauer-Emmett-Teller surface area measured in this series was 2404 m^2/g.Among the synthesized CTFs,CTF_（DCP） exhibited excellent CO_2 adsorption properties,with a CO_2 uptake of 225 mg/g at 0℃.展开更多
文摘Herein,we present a copper-catalyzed carbonylative cross-coupling of unactivated alkyl bromides with aryl boronates under CO atmosphere which enabling the efficient synthesis of C(sp3)-C(sp2)ketones with extensive functional group compatibility.This strategy represents a significant advance in copper-catalyzed carbonylation involving alkyl bromides and C(sp2)-nucleophiles.The protocol addresses key challenges commonly encountered in the coupling of C(sp3)-alkyl halides with aryl boron reagents,such as sluggish oxidative addition of alkyl halides,competing Suzuki-Miyaura cross-coupling,undesired dehalogenation and so on.Distinguished by its broad substrate scope and high functional group tolerance,this approach offers a robust and versatile platform for the streamlined synthesis of alkyl aryl ketones.
基金supported by the National Key R&D Program of China(2016YFC0203900,2016YFC0203901)National Natural Science Foundation of China(51778619,21577173)~~
文摘Alkali and alkaline‐earth metals from fly ash have a significant deactivation effect on catalysts used for selective catalytic reduction of NOx by NH3(NH3‐SCR).Bromides are considered effective additives to improve Hg0 oxidation on SCR catalysts.In this work,the effects of different bromides(NH4Br,NaBr,KBr,and CaBr2)on a commercial V2O5‐WO3/TiO2 catalyst were studied.NOx conversion decreased significantly over the KBr‐poisoned catalyst(denoted as L‐KBr),while that over NaBr‐and CaBr2‐poisoned catalysts(denoted as L‐NaBr and L‐CaBr,respectivity)decreased to a lesser extent compared with the fresh sample.Poor N2 selectivity was observed over L‐NaBr,L‐KBr and L‐CaBr catalysts.The decrease in the ratio of chemisorbed oxygen to total surface oxygen(Oα/(Oα+Oβ+Ow)),reducibility and surface acidity might contribute to the poor activity and N2 selectivity over L‐KBr catalyst.The increased Oαratio was conducive to the enhanced reducibility of L‐CaBr.Combined with enhanced surface acidity,this might offset the negative effect of the loss of active sites by CaBr2 covering.The overoxidation of NH3 and poor N2 selectivity in NH3 oxidation should retard the SCR activity at high temperatures over L‐CaBr catalyst.The increased basicity might contribute to increased NOx adsorption on L‐KBr and L‐CaBr catalysts.A correlation between the acid‐basic and redox properties of bromide‐poisoned catalysts and their catalytic properties is established.
基金supported by the Natural Science Foundation of Liaoning Education Department (No. 2008T094)
文摘Highly active, air-stable and water-soluble palladium-phosphinous acid complexes have been applied to Suzuki cross-coupling reaction of heteroaryl bromides under mild conditions in water/alcoholic solvents. Suzuki cross-coupling reaction of heteroaryl bromides with phenylboronic acid occurred efficiently using palladium phosphinous acid complexes （POPd） and phase transfer catalyst （tetrabutylammonium bromide and polyethylene glycol） in water/ethanol mixture, water/propanol mixture and neat water respectively, the corresponding yields of cross-coupling heteroaryl-aryls were satisfied. The tert-butyl substituted ligand di-tert-butylphosphino in combination with POPd was found to be more active than the same family derived catalysts dipalladium complexes POPdl and POPd2, and other two kinds of Pd-catalysts Pd（PPh3）4 and Pd2（dba）3. The mechanism of Suzuki cross-coupling reaction between heteroaryl bromides and phenylboronic acid in water was proposed with respect to the key role of phase transfer catalyst on the transmetallation step. Compared with other solid phase transfer catalysts, TBAB was tested as the ideal one. The alkalinity of base and the molar proportion between POPd and TBAB were investigated in water and alcoholic solvents. Notably, in the presence of TBAB adding alcoholic solvents into water enhanced the yields of target products. However in terms of the liquid phase transfer catalyst of PEGs, mixing water into PEGs could slightly decrease the yields with respect to the water free PEGs bulk phase, which was probably due to the homogenous liquid conditions in pure PEGs and weak interactions between PEGs and heteroaryl bromide molecules in water depending on their molecular chain lengths.
基金supported by the Ho Chi Minh City Department of Science and Technology, Viet Nam
文摘A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen adsorption. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid. The recovery of catalyst was simply by magnetic decantation in the presence of a magnet. The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity. No leaching of active palladium species into the reaction solution was detected.
基金The project was supported by the National Natural Science Foundation of China !(GrantNo.29803005) China Postdoctoral Science
文摘The catalytic effects for the oxidative methylation of toluene with methane over the basic zeolite catalysts prepared by promoting KY, KX, KM, KZSM-5 or KP with alkali-metal bromides and alkali-metal oxides have been investigated comparatively. The alkali-metal bromides promoted substrates are more effective than the alkali-metal oxides promoted systems. Moreover, the NaBr promoted systems are more active than KBr promoted systems. The most effective catalytic system (8wt%NaBr)/KZSM-5 gave a toluene conversion as high as 76.3% and a total C-8 selectivity of 76.4% (styrene/ethylbenzene=9.76) resulting in a total C-8 yield of 58.3%.
文摘The integral heat of solution of REBr 3·3Gly·3H 2O(RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y; Gly is glycine) in water, REBr 3· n H 2O(RE=La, Ce and Pr, n =7; RE=Nd, Sm, Eu, Gd, Tb, Dy and Y, n =6) in aqueous glycine solution and glycine in water have been measured calorimetrically at 298 15±0 15 K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation of REBr 3·3Gly·3H 2O have been obtained and their lattice energies have been calculated.
基金supported by the Natural Science Foundation of Shanghai,China(No.06ZR14085)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry.
文摘A convenient one-pot synthesis of functionalized （E）-2-arylvinyl bromides was achieved by microwave-induced deacetylation and subsequent acylation using dicyclohexyl carbodiimide （DCC） and dimethylamino-pyridine （DMAP） at room temperature from （E）-4-（2-bromovinyl）phenyl acetate.
基金Project supported by the National Natural Science Foundation of China(No.22301128)。
文摘A highly efficient and metal-free catalytic system for the synthesis of various selenylated maleimides and alkene derivatives via ammonium bromide-catalyzed direct selenylation of C(sp^(2))—H bond in maleimides and 1,1-diaryl alkenes using elemental selenium and boronic acids as the selenyl source is developed.Simple catalytic conditions,wide substrate scope,good functional group compatibility,scalable-up,and easy operation are presented in this strategy.The preliminary mechanism reveals that a radical pathway is possibly involved.
基金supported by the National Natural Science Foundation of China (22008049 and 22478095)Hebei Provincial Key Research Projects (22374101D)+3 种基金Central Guidance Project for Local Science and Technology Development from S&T Program of Hebei (246Z1009G)Special Proof-of-concept Project on Basic Research from S&T Program of Hebei (E2024402143)Science and Technology Project of Hebei Education Department (CXY2023004)Hebei University of Engineering Doctoral Scientific Research Start-up Foundation (SJ2401002210).
文摘Aiming at the problems of complex process and high cost in the production of potassium bromide at present,the solubility data and the phase diagram of the quaternary system KBr-MgBr_(2)-K_(2)SO_(4)-MgSO_(4)-H_(2)O at 298.15 K were studied using the isothermal dissolution equilibrium method.The results showed that there are eight invariant points,sixteen univariant curves,and nine crystallization regions in the phase diagram which is complex and contains two double salts(K_(2)SO_(4)·MgSO_(4)·6H_(2)O and KBr·MgBr_(2)·6H_(2)O)and a metastable phase(MgSO_(4)·5H_(2)O).On the basis of the Pitzer model and HW model,the solubilities of the quaternary system were calculated,with which the corresponding phase diagram was plotted.By comparison,the evaluated phase diagram is in accordance with the measured one.Through analysis,the phase diagrams of the quaternary system at(298.15 and 323.15)K were combined to put forward a process to separate KBr from the system by evaporation and crystallization,which realized the full circulation of the mother solution.
基金supported by the Natural Science Foundation of Qinghai Province(2024-ZJ-901).
文摘As an important strategic reserve resource,the comprehensive development and utilization of Nanyishan oil-gas field brine will bring great economic and social value.Here,according to the composition characteristics of this oil-gas field brine being rich in lithium,potassium and strontium,the solid-liquid stable phase equilibria and phase diagrams of Li-containing quaternary system(LiBr-MgBr_(2)-SrBr_(2)-H_(2)O)and two quinary systems(LiBr-NaBr-MgBr_(2)-SrBr_(2)-H_(2)O and LiBr-KBr-MgBr_(2)-SrBr_(2)-H_(2)O)were studied at 298.15 K.Based on the results of phase equilibrium experimental research,the phase equilibrium relationship and crystallization-dissolution behavior of each component in liquid phase were revealed theoretically,and the changing trend was summarized.Using theoretical model of Pitzer electrolyte solution,the relevant interaction parameters of mixed ions at 298.15 K were obtained by fitting experimental data,and the solubility reaching equilibrium of various salts in above systems was calculated,and the experimental results were verified.The research results of this paper lay an important foundation for further theoretical study of multi-temperature phase equilibrium and thermodynamic properties of complex brine system in the later stage.Meanwhile,it provides basic thermodynamic data and theoretical guidance for the rational development and comprehensive utilization of this oil-gas field brine resources.
基金The authors acknowledge the University of Sharjah for financial support through a competitive research project grant(project number:23020406277)。
文摘As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the currently adopted polyatomic and metal complex anion intercalation process at the graphite electrode in ZnGB exhibits poor electrochemical performances.Alternatively,incorporating halogen anions offers exceptional electrochemical performance to graphite electrodes due to their redox process.In this work,ZnGBs are assembled using a LiCl/ZnCl2/KBr^(-)based water-in-salt electrolyte,which efficiently supplies bromide(Br^(−))ions for conversion into Br_(x)^(−)and facilitates Br_(2)intercalation at the graphite electrode.The conversion and intercalation of bromine together enable the ZnGB to achieve a discharge capacity of 2.73 mAh/cm^(2)with 91.0%of coulombic efficiency(CE)while supporting high current density operations of up to 150 mA/cm^(2).With high energy density(4.56 Wh/cm^(2)),high power density(199.5 mW/cm^(2)),and excellent rate capability(∼93.0%CE at 150 mA/cm^(2)),the ZnGB is shown to operate efficiently for as much as 800 cycles.Beguilingly,an anode-free ZnGB offers enhanced stability for up to 1100 cycles without performance decay,matching the electrochemical performance of Zn metal electrodes.This work provides insights into the bromine reaction mechanism at graphite electrodes and the role of surface exfoliation in enabling efficient Br_(x)^(−)formation,along with Br_(2)intercalation,for achieving high-performance ZnGBs.
基金The National Natural Science Foundation of China (No. 42377020)the Innovation Project of Nanjing Water Group Co.,Ltd.(No. YF2025-009)。
文摘The widespread presence of organophosphate flame retardants(OPFRs)in aquatic environments has raised significant concerns regarding environmental and hu-man health risks.In this study,the adsorption behavior of two representative aromatic OPFRs,triphenylphosphine ox-ide(TPPO)and triphenyl phosphate(TPhP),was system-atically investigated using organically modified montmoril-lonite(MMT).The effects of various environmental and operational parameters,including cationic surfactant dos-age,temperature,pH,ionic strength,and humic acid(HA)concentration,on OPFR adsorption were thoroughly examined.Results revealed that modification with hexa-decyltrimethylammonium bromide enhanced the TPPO and TPhP adsorption capacities of MMT.The adsorption pro-cess was largely independent of pH and HA concentration,and the presence of inorganic cations significantly improved the adsorption efficiency.Adsorption equilibrium was achieved within 30 min,with kinetics best described by a pseudo-second-order model.The adsorption isotherms ex-hibited a linear relationship,and the distribution coefficients for TPPO and TPhP were 0.16 and 0.51 L/g,respectively.Thermodynamic analysis indicated that the considered ad-sorption was more favorable at lower temperatures.The pri-mary adsorption mechanism was attributed to the partition-ing behavior facilitated by the organophilic nature of the modified MMT.Moreover,the adsorbent demonstrated ex-cellent regeneration performance,with its adsorption capac-ity remaining stable over five consecutive cycles.Overall,these findings show that cationic surfactant-modified MMT has a promising potential for application in wastewater treat-ment to effectively remove OPFRs from aqueous systems.
基金provided by the National Natural Science Foundation of China(Grant No.52373208 and 61831021)the ECNU Academic Innovation Promotion Program for Excellent Doctoral Students(YBNLTS2024-021).
文摘The coupling of fast redox kinetics,high-energy density,and prolonged lifespan is a permanent aspiration for aqueous rechargeable zinc batteries,but which has been severely hampered by a narrow voltage range and suboptimal compatibility between the electrolytes and electrodes.Here,we unprecedentedly introduced an electric ambipolar effect for synergistic manipulation on Zn^(2+)ternary-hydrated eutectic electrolyte(ZTE)enabling high-performance Zn-Br_(2)batteries.The electric ambipolar effect motivates strong dipole interactions among hydrated perchlorates and bipolar ligands of L-carnitine(L-CN)and sulfamide,which reorganized primary cations solvation sheath in a manner of forming Zn[(L-CN)(SA)(H_(2)O)_(4)]^(2+)configuration and dynamically restricting desolvated H2O molecules,thus ensuring a broadened electrochemical window of 2.9 V coupled with high ionic conductivity.Noticeably,L-CN affords an electrostatic shielding effect and an in situ construction of organic-inorganic interphase,endowing oriented Zn anode plating/stripping reversibly for over 2400 h.Therefore,with the synergy of electro/nucleophilicity and exceptional compatibility,the ZTE electrolyte dynamically boosts the conversion redox of Zn-Br_(2)batteries in terms of high specific capacity and stable cycling performance.These findings open a window for designing electrolytes with synergetic chemical stability and compatibility toward advanced zinc-ion batteries.
基金Qingdao Marine Science and Technology Center(No.2022QNLM030003-2)Taishan Scholar Program of Shandong Province(No.tsqn202103152)National Natural Science Foundation of China(Nos.22201270,22471250)for financial support.
文摘Despite the widespread use of allyl bromides in organic synthesis,the asymmetric transformation of allyl bromides has been less developed.To date,the asymmetric transformation of allyl bromides has been limited to single-site functionalization,and the development of dual-site asymmetric functionalization remains unexplored.In this work,the unprecedented asymmetric dual-site functionalization of allyl bromides has been realized through an efficient organocatalytic system,overcoming the persistent limitation of single-site transformations.Employing dinucleophiles including 3-aminobenzofurans,2-aminoindoles,and cyclohexane-1,3-diones,this methodology affords benzofuro[3,2-b]pyridines andα-carbolines in good yields with excellent stereoselectivity.The transformation proceeds via a chemoselective S_(N)2′pathway mediated by a chiral pyrrolidinyl sulfonamide catalyst,which generates ammonium salts in situ to achieve stereocontrol.The protocol was successfully extended to enantioenriched privileged pyran frameworks,and was applied to diverse downstream transformations.Gram-scale synthesis maintained high enantioselectivity,confirming practical utility.This approach effectively addresses key challenges in efficient construction of complex fused-ring heterocycles,substantially expanding the synthetic applications of allyl bromides.
基金Projects(51102285,81170912)supported by the National Natural Science Foundation of ChinaProject supported by the Open Foundation of State Key Laboratory of Powder Metallurgy,China
文摘The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.
基金Project (30770838) supported by the National Natural Science Foundation of China Project (2008WK2003) supported by Hunan Science and Technology Foundation, China+1 种基金 Project (2010QZZD006) supported by the Key Program of Central South University Advancing Front Foundation, China Project (200806) supported by Opening Foundation of State Key Laboratory of Powder Metallurgy, Central South University, China
文摘Functionalized carbon nanotubes （CNTs） were made for the delivery of genes and drugs and CNT-based biosensors. The basis of CNTs is for binding with biomolecules in biomedical applications. The binding tendency with small interfering RNA oligonucleotides and cytotoxicity of cetyltrimethyl ammonium bromide （CTAB）-coated single-walled carbon nanotubes （SWNTs） were studied. The field emission scanning electron microscopy and transmission electron microscopy results show that a SWNT suspension in CTAB solution was well-dispersed and stable. CTAB is the cross-linker between SWNTs and oligonucleotides. The CTAB-coated SWNTs have less cytotoxicity to human umbilical vein endothelial cells than single SWNTs and the cytotoxicity of CTAB-coated SWNTs depended on the concentration of CTAB-coated SWNTs.
基金supported by the National Natural Science Foundation of China(21373202,21525315)~~
文摘Covalent triazine-based frameworks（CTFs） are important microporous materials with a wide range of applications.Here,we demonstrate an environmentally benign and economic synthetic pathway to CTFs.The monomers used for CTFs,aromatic nitriles,were obtained by cyanation using nontoxic potassium hexacyanoferrate（Ⅱ） in place of commonly used toxic cyanides.Then,the CTFs were synthesized by trimerization of the corresponding cyano monomers in molten zinc chloride.A series of CTFs was synthesized,and the highest Brunauer-Emmett-Teller surface area measured in this series was 2404 m^2/g.Among the synthesized CTFs,CTF_（DCP） exhibited excellent CO_2 adsorption properties,with a CO_2 uptake of 225 mg/g at 0℃.
