The synergistic extraction of Pr^3＋ from hydrochloric medium using mixture of 2-ethylhexyl phosphonic acid mono- 2-ethylhexyl ester （P507, HL） and 8-Hydroxyquinoline （HQ） in heptane was investigated. The effect o...The synergistic extraction of Pr^3＋ from hydrochloric medium using mixture of 2-ethylhexyl phosphonic acid mono- 2-ethylhexyl ester （P507, HL） and 8-Hydroxyquinoline （HQ） in heptane was investigated. The effect of equilibrium of aqueous acidity on extraction of Pr^3＋ was discussed. The effect of extractant concentraction, different diluents, equilibrium time and acetate ion concentration oil extraction reaction were also studied. With a method of double-logarithmic slope, composition of the extracted species on 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester and 8-Hydroxyquinoline was derived. The result shows that the synergistic extraction system not only overcomes emulsification of 8-Hydroxyquinoline, but also shows perfect capacity of synergistic extraction. The largest synergistic enhancement factor can be calculated to be 5.49 at pH 3.6 for Pr^3＋.展开更多
A method using N,O-bis（trimethylsilyl）acetamide/N-hydroxysuccinimide ester（BSA/NHS） as coupling agents for dipeptide synthesis is descried. The coupling reaction between N-hydroxysuccinimide（NHS）esters and amine...A method using N,O-bis（trimethylsilyl）acetamide/N-hydroxysuccinimide ester（BSA/NHS） as coupling agents for dipeptide synthesis is descried. The coupling reaction between N-hydroxysuccinimide（NHS）esters and amines could be performed under mild conditions with N,O-bis（trimethylsilyl）acetamide（BSA） as coupling reagent and no additional acid/base is required. All byproducts and excessive reactants are water soluble or hydrolysable and easy to eliminate through water-washing at the purification stage.Moreover, all the reactants are inexpensive and widely used in conventional drug production.展开更多
（S）-2-aminobutyric acid being initial raw material,（S）-2-hydroxybutyric acid methyl ester was synthesized by means of a three step reaction of hydroxylation, salification and esterification. The product had a yiel...（S）-2-aminobutyric acid being initial raw material,（S）-2-hydroxybutyric acid methyl ester was synthesized by means of a three step reaction of hydroxylation, salification and esterification. The product had a yield rate of 60.4%, purity of 99% and ee value higher than 99% by characterization of GC, HPLC and 1H NMR. This synthesis technique has advantages of high purity and ee value, low cost, short reaction time and mild reaction conditions so that it is suitable for production on industrial scale.展开更多
To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversibleβ-hydroxyl ester bonds w...To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversibleβ-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth(GFC@BNNSs).The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs.Then,the GFC@BNNSs were impregnated with the mixture of lower concentration(3-glycidyloxypropyl)trimethoxysilane grafted BN micron sheets,3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride,which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances.The resultant GFREP composite containing less boron nitride particles(17.6 wt%)exhibited superior in-plane(3.29 W·m^(-1)·K^(-1))and through-plane(1.16 W·m^(-1)·K^(-1))thermal conductivities,as well as high Tg of 204℃(Tg of the unfilled epoxy=177℃).The reversible transesterification reaction enabled closure of interlaminar cracks within the composite,achieving decent healing efficiencies estimated by means of tensile strength(71.2%),electrical breakdown strength(83.6%)and thermal conductivity(69.1%).The present work overcame the disadvantages of conventional thermally conductive composites,and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application.展开更多
Various aromatic α-keto esters were rapidly and selectively reduced to aromatic α-hydroxy esters by commercially available zinc dust and ammonium formate in the presence of other functional groups such as halogens, ...Various aromatic α-keto esters were rapidly and selectively reduced to aromatic α-hydroxy esters by commercially available zinc dust and ammonium formate in the presence of other functional groups such as halogens, methoxy and esters.展开更多
We report here a generic,green synthesis of 17 valuable syn-aryl-(2S,3R)-2–chloro-3–hydroxy esters(syn-(2S,3R)-1)in 73%-99%isolated yields along with 6.1:1–83:1 dr and 31%~>99%ee,through dynamic reductive kineti...We report here a generic,green synthesis of 17 valuable syn-aryl-(2S,3R)-2–chloro-3–hydroxy esters(syn-(2S,3R)-1)in 73%-99%isolated yields along with 6.1:1–83:1 dr and 31%~>99%ee,through dynamic reductive kinetic resolution of racemic arylα–chloroβ-keto esters(2)catalyzed by an engineered ketoreductase which was obtained via ep PCR-based directed evolution.The hectogram scale synthesis of syn-(2S,3R)-1b at a substrate concentration of 120 g/L showcased the application potential of the biocatalytic method developed presently.展开更多
An electrochemically promoted decarboxylative borylation reaction is reported. The reaction proceeds under mild conditions in an undivided cell without use of transition metal-or photo-catalysts. The key feature of th...An electrochemically promoted decarboxylative borylation reaction is reported. The reaction proceeds under mild conditions in an undivided cell without use of transition metal-or photo-catalysts. The key feature of the reaction is the compatibility of diboron reagents with the electrochemical conditions. This reaction exhibits broad substrate scope, good functional group tolerability, and easy scalability.展开更多
An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist o...An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist of inexpensive rose bengal as photocatalyst to prepare a series of alkyl substituted oxazolines in moderate to excellent yields. High regioselectivity, operational safety, mild conditions and excellent substrate generality give this protocol broad application prospects.展开更多
Starch grafted poly-hydroxy alkyl-acid esters were prepared via graft polymerization.Different characteristics of grafted starches were tested such as viscosity,viscosity stability,adhesion as well as properties of si...Starch grafted poly-hydroxy alkyl-acid esters were prepared via graft polymerization.Different characteristics of grafted starches were tested such as viscosity,viscosity stability,adhesion as well as properties of sized yarns.Sizing performance was analyzed from the aspect of physical and chemical reactions between polymer molecules.It shows that starch grafted poly-hydroxy alkyl-acid esters have excellent sizing performance and could absolutely be used as sizes for polyester-cotton yarns.展开更多
The optically active R-4-phenyl-2-hydroxy butyrates were prepared by esterification of the racemic acid or transesterification of the racemic ester catalyzed by lipase from Candida cyclindra (CCL) in organic media.
Fifty agricultural soil samples collected from Fuzhou,southeast China,were first investigated for the occurrence,distribution,and potential risks of twelve organophosphate esters(OPEs).The total concentration of OPEs(...Fifty agricultural soil samples collected from Fuzhou,southeast China,were first investigated for the occurrence,distribution,and potential risks of twelve organophosphate esters(OPEs).The total concentration of OPEs(ΣOPEs)in soil ranged from 1.33 to 96.5 ng/g dry weight(dw),with an average value of 17.1 ng/g dw.Especially,halogenated-OPEs were the predominant group with amean level of 9.75 ng/g dw,and tris(1-chloro-2-propyl)phosphate(TCIPP)was the most abundant OPEs,accounting for 51.1%ofΣOPEs.The concentrations of TCIPP andΣOPEs were found to be significantly higher(P<0.05)in soils of urban areas than those in suburban areas.In addition,the use of agricultural plastic films and total organic carbon had a positive effect on the occurrence of OPE in this study.The positive matrix factorization model suggested complex sources of OPEs in agricultural soils from Fuzhou.The ecological risk assessment demonstrated that tricresyl phosphate presented a medium risk to land-based organisms(0.1≤risk quotient<1.0).Nevertheless,the carcinogenic and noncarcinogenic risks for human exposure to OPEs through soil ingestion and dermal absorption were negligible.These findings would facilitate further investigations into the pollution management and risk control of OPEs.展开更多
Phthalic acid esters(PAEs)are a group of compounds widespread in the environment.To investigate the occurrence and accumulation characteristics of PAEs,surface water samples were collected from the Three Gorges Reserv...Phthalic acid esters(PAEs)are a group of compounds widespread in the environment.To investigate the occurrence and accumulation characteristics of PAEs,surface water samples were collected from the Three Gorges Reservoir area,China.The total concentrations of∑_(11)analyzed PAEs(11PAEs)in the collected water samples ranging from 197.7 to 1,409.3 ng/L(mean±IQR:583.1±308.4 ng/L).While DEHP was the most frequently detected PAE,DnBP and DnNP were the most predominant PAEs in the analyzed water samples with a mean contribution of 63.3%of the∑_(11)PAEs.The concentrations of the∑_(11)PAEs in the water samples from the upper reaches of the Yangtze River were significantly higher than those from themiddle reaches.To better understand the transport and fate of the PAEs,seven detected PAEs were modeled by Quantitative Water Air Sediment Interaction(QWASI).The simulated and measured values were close for most PAEs,and differences are within one order of magnitude even for the worst one.For all simulated PAEs,water and particle inflow were main sources in the reservoir,whereas water outflow and degradation in water were important removal pathways.The contribution ratios of different sources/losses varied fromPAEs,depending on their properties.The calculated risk quotients of DnNP in the Three Gorges Reservoir area whether based onmonitoring or simulating results were all far exceeded the safety threshold value,implying the occurrence of this PAE compound may cause potential adverse effects for the aquatic ecology of the Three Gorges Reservoir area.展开更多
The efficient hydrogenolysis of esters to alkanes is the key protocol for producing advanced biofuels from renewable plant oils or fats.Due to the low reactivity of the carbonyl group in esters,a high reaction tempera...The efficient hydrogenolysis of esters to alkanes is the key protocol for producing advanced biofuels from renewable plant oils or fats.Due to the low reactivity of the carbonyl group in esters,a high reaction temperature(>250℃)is the prerequisite to ensure high conversion of esters.Here,we report a highly dispersed MoO_(x)-Ru/C bimetallic catalyst for the efficient hydrogenolysis of esters to alkanes under 150°C.The optimal catalyst exhibits>99%conversion of methyl stearate and 99%selectivity to diesel-range alkanes,reaching a high rate of up to 2.0 mmol gcat^(–1)h^(–1),5 times higher than that of Ru/C catalyst(MoO_(x)/C is inert).Integrated experimental and theoretical investigations attribute the high performance to the abundant MoO_(x)-Ru interfacial sites on the catalyst surface,which offers high activity for the C–O cleavage of esters.Furthermore,the dispersed MoO_(x)species significantly weaken the hydrocracking activity of the metallic Ru for C–C bonds,thus yielding alkane products without carbon loss.This study provides a facile and novel strategy for the design of high-performance heterogeneous catalysts for the hydrodeoxygenation of biomass-derived esters to alkane products.展开更多
It is important to understand the evolution of the matter on the polymer membrane surface.The in situ and real-time monitoring of the membrane surface will not only favor the investigation of selective layer formation...It is important to understand the evolution of the matter on the polymer membrane surface.The in situ and real-time monitoring of the membrane surface will not only favor the investigation of selective layer formation but can also track the fouling process during operation.Herein,an aggregation-induced emission(AIE)-active polymer membrane was prepared by the interfacial polymerization of a cyclodextrin-based glycocluster(CD@Glucose)and a tetraphenylethylene derivative modified with boronic acid groups(TPEDB)on the surface of a polyacrylonitrile(PAN)ultrafiltration membrane.This interfacial polymerization method can be stacked layer-by-layer to regulate the hydrophilicity and pore structure of the membrane.With the increase in the number of polymer layers,the separation and antifouling properties of the membrane gradually improved.Owing to the AIE property of the crosslinking agent TPEDB,the occurrence of interfacial polymerization and the degree of fouling during membrane operation can be monitored by the fluorescence distribution and intensity.With the aggravation of membrane fouling,the fluorescence decreased gradually,but recovered after cleaning.Therefore,this AIE effect can be used for real-time monitoring of interfacial polymerization as well as membrane fouling.展开更多
Phthalic acid esters(PAEs)are widely released into the environment due to industrial and agricultural activities.This poses significant risks,not only to crops grown on contaminated soil but also to humans.PAEs enter ...Phthalic acid esters(PAEs)are widely released into the environment due to industrial and agricultural activities.This poses significant risks,not only to crops grown on contaminated soil but also to humans.PAEs enter the human body through the food chain,causing potential health hazards.Endophytic bacteria have demonstrated a significant potential as effective bioremediation agents,with specialized mechanisms of PAEs degradation.Endophytic bacteria such as Rhodococcus,Pseudomonas and Sphingomona recognize root exudates,adhere to and penetrate root surfaces,and ultimately colonize crops.They form symbiotic relationships with crops,obtaining nutrients and habitats from crops,meanwhile,promoting plant growth and health through hormone production,nutrient regulation,and the suppression of pathogenic microorganisms.Furthermore,endophytic bacteria efficiently degrade PAEs in soil-crop systems through synergistic interactions with indigenous rhizosphere microflora and regulatory effects on enzyme activity in crops.Here,we review the role of endophytic bacteria in the bioremediation of PAEs-contaminated crops and soils.In addition,we discuss the scarcity of endophytic bacterial strains with a confirmed ability to degrade PAEs,and underscore the lack of the research on the mechanisms of PAEs degradation by these bacteria.This review also points out that future study should investigate the molecular mechanisms underlying the interaction between endophytic bacteria and PAEs to offer novel insights and solutions for environmental protection and sustainable agricultural development.展开更多
Different reactive flame retardants have been extensively developed for vinyl ester resins(VERs),but very few of them can yield a flame-retardant resin that meets defined standards(e.g.UL-94 V-0 rating).In this work,p...Different reactive flame retardants have been extensively developed for vinyl ester resins(VERs),but very few of them can yield a flame-retardant resin that meets defined standards(e.g.UL-94 V-0 rating).In this work,phosphorous-containing 1-vinylimidazole salts(called VIDHP and VIDPP)were synthesized through the facile neutralization of the acid and 1-vinylimidazole.VIDHP and VIDPP were then applied as flame-retardant crosslinking agents of VERs,by which phosphorus-containing groups could be incorporated into the resin chain via ionic bonds.VIDHP/VER and VIDPP/VER showed a high curing activity and can be well cured in moderate temperatures.With 20 wt.%additions of VIDHP and VIDPP,VIDHP20/VER,and VIDPP20/VER presented a limiting oxygen index value of 29.7%and 28.4%,respectively,with the latter achieving a UL 94 V0 rating.In the cone calorimetric test,compared to the unmodified VERs,VIDPP20/VER exhibited large reductions in the peak heat release rate,total heat release rate,and total smoke release rate while VIDHP20/VER demonstrated comparatively inferior performance in terms of the heat release.VIDHP20/VER and VIDPP20/VER showed good thermal stability and presented a little lower glass transition temperature than the control sample.VIDPP with a low phosphorus oxidation state(+1)demonstrated high flame-retardant activities in the gaseous phase,whereas VIDHP with a high phosphorus oxidation state(+5)primarily exhibited efficacy in the condensed phase.展开更多
A new methodology was advanced that mesogenic cores appeared after theformation of urethane groups and during the monomer-to-polymer transition. A newdiphenol monomer, bis(4'-hydroxy-phenyl)-toluene-2 (BHPTU), was...A new methodology was advanced that mesogenic cores appeared after theformation of urethane groups and during the monomer-to-polymer transition. A newdiphenol monomer, bis(4'-hydroxy-phenyl)-toluene-2 (BHPTU), was obtainedby the reaction of 2,4-tolulene diisocyanate with hydroquinone in dioxane or N,N-dimethyl-acetandde. The reaction process was monitored by FTIR, and the product was investigated bylH NMR and elemental analysis (EA). A liquid crystalline poly(urethane-ester) was obtainedusing the BHPTU monomer.展开更多
The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques inc...The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.展开更多
A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is ver...A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).展开更多
An efficient synthesis of α-thioenamine compounds via a K_(2)S_(2)O_(8)-promoted cross-dehydrogenative coupling reaction between heterocyclic thiols and enamine esters in an aqueous medium has been developed.The reac...An efficient synthesis of α-thioenamine compounds via a K_(2)S_(2)O_(8)-promoted cross-dehydrogenative coupling reaction between heterocyclic thiols and enamine esters in an aqueous medium has been developed.The reaction showed good tolerance for enamine esters and heterocyclic thiols with various functional groups,producingα-thioenamine derivatives in moderate to high yields.Mechanistic studies revealed that heterocyclic thiols react with K_(2)S_(2)O_(8) in water to form reactive disulfides in situ,which then react with enamine esters to generate a series ofα-thioenamines.Building on the proposed mechanism,we developed a sulfenylation reaction of enamine esters with disulfides without the need for an oxidant.This oxidant-free approach has been successfully employed to synthesize DNA-taggedα-thioenamine,demonstrating its considerable potential for various synthetic applications.展开更多
文摘The synergistic extraction of Pr^3＋ from hydrochloric medium using mixture of 2-ethylhexyl phosphonic acid mono- 2-ethylhexyl ester （P507, HL） and 8-Hydroxyquinoline （HQ） in heptane was investigated. The effect of equilibrium of aqueous acidity on extraction of Pr^3＋ was discussed. The effect of extractant concentraction, different diluents, equilibrium time and acetate ion concentration oil extraction reaction were also studied. With a method of double-logarithmic slope, composition of the extracted species on 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester and 8-Hydroxyquinoline was derived. The result shows that the synergistic extraction system not only overcomes emulsification of 8-Hydroxyquinoline, but also shows perfect capacity of synergistic extraction. The largest synergistic enhancement factor can be calculated to be 5.49 at pH 3.6 for Pr^3＋.
基金financially supported by the National Science and Technology Major Project of China(No.521042)
文摘A method using N,O-bis（trimethylsilyl）acetamide/N-hydroxysuccinimide ester（BSA/NHS） as coupling agents for dipeptide synthesis is descried. The coupling reaction between N-hydroxysuccinimide（NHS）esters and amines could be performed under mild conditions with N,O-bis（trimethylsilyl）acetamide（BSA） as coupling reagent and no additional acid/base is required. All byproducts and excessive reactants are water soluble or hydrolysable and easy to eliminate through water-washing at the purification stage.Moreover, all the reactants are inexpensive and widely used in conventional drug production.
文摘（S）-2-aminobutyric acid being initial raw material,（S）-2-hydroxybutyric acid methyl ester was synthesized by means of a three step reaction of hydroxylation, salification and esterification. The product had a yield rate of 60.4%, purity of 99% and ee value higher than 99% by characterization of GC, HPLC and 1H NMR. This synthesis technique has advantages of high purity and ee value, low cost, short reaction time and mild reaction conditions so that it is suitable for production on industrial scale.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52033011,51973237 and 52373095)Natural Science Foundation of Guangdong Province,China(Nos.2019B1515120038 and 2021A1515010417)+2 种基金Science and Technology Planning Project of Guangdong Province(No.2020B010179001)Science and Technology Planning Project of Guangzhou City(No.202201011568)GBRCE for Functional Molecular Engineering,and Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.23yxqntd002).
文摘To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversibleβ-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth(GFC@BNNSs).The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs.Then,the GFC@BNNSs were impregnated with the mixture of lower concentration(3-glycidyloxypropyl)trimethoxysilane grafted BN micron sheets,3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride,which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances.The resultant GFREP composite containing less boron nitride particles(17.6 wt%)exhibited superior in-plane(3.29 W·m^(-1)·K^(-1))and through-plane(1.16 W·m^(-1)·K^(-1))thermal conductivities,as well as high Tg of 204℃(Tg of the unfilled epoxy=177℃).The reversible transesterification reaction enabled closure of interlaminar cracks within the composite,achieving decent healing efficiencies estimated by means of tensile strength(71.2%),electrical breakdown strength(83.6%)and thermal conductivity(69.1%).The present work overcame the disadvantages of conventional thermally conductive composites,and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application.
文摘Various aromatic α-keto esters were rapidly and selectively reduced to aromatic α-hydroxy esters by commercially available zinc dust and ammonium formate in the presence of other functional groups such as halogens, methoxy and esters.
基金The National Key Research and Development Program of China(Nos.2021YFA0911400 and 2021YFF0600704)the National Natural Science Foundation of China(Nos.22071033 and 21801047)are acknowledged for the financial supports。
文摘We report here a generic,green synthesis of 17 valuable syn-aryl-(2S,3R)-2–chloro-3–hydroxy esters(syn-(2S,3R)-1)in 73%-99%isolated yields along with 6.1:1–83:1 dr and 31%~>99%ee,through dynamic reductive kinetic resolution of racemic arylα–chloroβ-keto esters(2)catalyzed by an engineered ketoreductase which was obtained via ep PCR-based directed evolution.The hectogram scale synthesis of syn-(2S,3R)-1b at a substrate concentration of 120 g/L showcased the application potential of the biocatalytic method developed presently.
基金supported by the National Natural Science Foundation of China (Nos. 21871074 and 21971051)the National Key R&D Program of China (No. 2018YFB1501604)+1 种基金the Fundamental Research Funds for the Central Universities (No. PA2020GDKC0021)the Key Research and Development Program Projects in Anhui Province (No. 201904a07020069)。
文摘An electrochemically promoted decarboxylative borylation reaction is reported. The reaction proceeds under mild conditions in an undivided cell without use of transition metal-or photo-catalysts. The key feature of the reaction is the compatibility of diboron reagents with the electrochemical conditions. This reaction exhibits broad substrate scope, good functional group tolerability, and easy scalability.
基金supported by the National Natural Science Foundation of China (No. 22078299)Zhejiang Provincial Natural Science Foundation of China (Nos. LY21B060005, LQ20B060007)+1 种基金the College of Pharmaceutical Sciences, Zhejiang University of TechnologyCollaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals for the financial help。
文摘An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist of inexpensive rose bengal as photocatalyst to prepare a series of alkyl substituted oxazolines in moderate to excellent yields. High regioselectivity, operational safety, mild conditions and excellent substrate generality give this protocol broad application prospects.
基金Key Projects in the National Science&Technology Pillar Program during the11th Five-Year Plan Period(No.2009BAE88B01)
文摘Starch grafted poly-hydroxy alkyl-acid esters were prepared via graft polymerization.Different characteristics of grafted starches were tested such as viscosity,viscosity stability,adhesion as well as properties of sized yarns.Sizing performance was analyzed from the aspect of physical and chemical reactions between polymer molecules.It shows that starch grafted poly-hydroxy alkyl-acid esters have excellent sizing performance and could absolutely be used as sizes for polyester-cotton yarns.
文摘The optically active R-4-phenyl-2-hydroxy butyrates were prepared by esterification of the racemic acid or transesterification of the racemic ester catalyzed by lipase from Candida cyclindra (CCL) in organic media.
基金supported by the Open Fund of the Laboratory for Earth Surface Processes,Ministry of Education,Peking University,Beijing,China,and the Cultivation Fund Program for Excellent Dissertation in Fujian Normal University,China(No.LWPYS202315)the Research Start-up Fund of Fujian Normal University,China(No.Y0720304X13).
文摘Fifty agricultural soil samples collected from Fuzhou,southeast China,were first investigated for the occurrence,distribution,and potential risks of twelve organophosphate esters(OPEs).The total concentration of OPEs(ΣOPEs)in soil ranged from 1.33 to 96.5 ng/g dry weight(dw),with an average value of 17.1 ng/g dw.Especially,halogenated-OPEs were the predominant group with amean level of 9.75 ng/g dw,and tris(1-chloro-2-propyl)phosphate(TCIPP)was the most abundant OPEs,accounting for 51.1%ofΣOPEs.The concentrations of TCIPP andΣOPEs were found to be significantly higher(P<0.05)in soils of urban areas than those in suburban areas.In addition,the use of agricultural plastic films and total organic carbon had a positive effect on the occurrence of OPE in this study.The positive matrix factorization model suggested complex sources of OPEs in agricultural soils from Fuzhou.The ecological risk assessment demonstrated that tricresyl phosphate presented a medium risk to land-based organisms(0.1≤risk quotient<1.0).Nevertheless,the carcinogenic and noncarcinogenic risks for human exposure to OPEs through soil ingestion and dermal absorption were negligible.These findings would facilitate further investigations into the pollution management and risk control of OPEs.
基金supported by the Innovation Fund of Nanjing Institute of Environmental Science,Ministry of Ecology and Environment,China(No.ZX2023QT003)the National Natural Science Foundation of China(No.22306130)+1 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2022ZB789)the Ecological Environment Research Project of Jiangsu Province,China(No.2022014).
文摘Phthalic acid esters(PAEs)are a group of compounds widespread in the environment.To investigate the occurrence and accumulation characteristics of PAEs,surface water samples were collected from the Three Gorges Reservoir area,China.The total concentrations of∑_(11)analyzed PAEs(11PAEs)in the collected water samples ranging from 197.7 to 1,409.3 ng/L(mean±IQR:583.1±308.4 ng/L).While DEHP was the most frequently detected PAE,DnBP and DnNP were the most predominant PAEs in the analyzed water samples with a mean contribution of 63.3%of the∑_(11)PAEs.The concentrations of the∑_(11)PAEs in the water samples from the upper reaches of the Yangtze River were significantly higher than those from themiddle reaches.To better understand the transport and fate of the PAEs,seven detected PAEs were modeled by Quantitative Water Air Sediment Interaction(QWASI).The simulated and measured values were close for most PAEs,and differences are within one order of magnitude even for the worst one.For all simulated PAEs,water and particle inflow were main sources in the reservoir,whereas water outflow and degradation in water were important removal pathways.The contribution ratios of different sources/losses varied fromPAEs,depending on their properties.The calculated risk quotients of DnNP in the Three Gorges Reservoir area whether based onmonitoring or simulating results were all far exceeded the safety threshold value,implying the occurrence of this PAE compound may cause potential adverse effects for the aquatic ecology of the Three Gorges Reservoir area.
文摘The efficient hydrogenolysis of esters to alkanes is the key protocol for producing advanced biofuels from renewable plant oils or fats.Due to the low reactivity of the carbonyl group in esters,a high reaction temperature(>250℃)is the prerequisite to ensure high conversion of esters.Here,we report a highly dispersed MoO_(x)-Ru/C bimetallic catalyst for the efficient hydrogenolysis of esters to alkanes under 150°C.The optimal catalyst exhibits>99%conversion of methyl stearate and 99%selectivity to diesel-range alkanes,reaching a high rate of up to 2.0 mmol gcat^(–1)h^(–1),5 times higher than that of Ru/C catalyst(MoO_(x)/C is inert).Integrated experimental and theoretical investigations attribute the high performance to the abundant MoO_(x)-Ru interfacial sites on the catalyst surface,which offers high activity for the C–O cleavage of esters.Furthermore,the dispersed MoO_(x)species significantly weaken the hydrocracking activity of the metallic Ru for C–C bonds,thus yielding alkane products without carbon loss.This study provides a facile and novel strategy for the design of high-performance heterogeneous catalysts for the hydrodeoxygenation of biomass-derived esters to alkane products.
基金supported by the Fundamental Research Funds for Central Universities(No.30922010811).
文摘It is important to understand the evolution of the matter on the polymer membrane surface.The in situ and real-time monitoring of the membrane surface will not only favor the investigation of selective layer formation but can also track the fouling process during operation.Herein,an aggregation-induced emission(AIE)-active polymer membrane was prepared by the interfacial polymerization of a cyclodextrin-based glycocluster(CD@Glucose)and a tetraphenylethylene derivative modified with boronic acid groups(TPEDB)on the surface of a polyacrylonitrile(PAN)ultrafiltration membrane.This interfacial polymerization method can be stacked layer-by-layer to regulate the hydrophilicity and pore structure of the membrane.With the increase in the number of polymer layers,the separation and antifouling properties of the membrane gradually improved.Owing to the AIE property of the crosslinking agent TPEDB,the occurrence of interfacial polymerization and the degree of fouling during membrane operation can be monitored by the fluorescence distribution and intensity.With the aggravation of membrane fouling,the fluorescence decreased gradually,but recovered after cleaning.Therefore,this AIE effect can be used for real-time monitoring of interfacial polymerization as well as membrane fouling.
基金supported by the National Natural Science Foundation of China(No.22161132011)Jiangsu Provincial Special Fund for S&T Innovation in Carbon Emission Peak and Neutrality(No.20220013)+1 种基金the National Key Research and Development Program of China(Nos.2023YFE0110800 and 2023YFC3708100)the Fundamental Research Funds for the Central Universities(No.QTPY2024001).
文摘Phthalic acid esters(PAEs)are widely released into the environment due to industrial and agricultural activities.This poses significant risks,not only to crops grown on contaminated soil but also to humans.PAEs enter the human body through the food chain,causing potential health hazards.Endophytic bacteria have demonstrated a significant potential as effective bioremediation agents,with specialized mechanisms of PAEs degradation.Endophytic bacteria such as Rhodococcus,Pseudomonas and Sphingomona recognize root exudates,adhere to and penetrate root surfaces,and ultimately colonize crops.They form symbiotic relationships with crops,obtaining nutrients and habitats from crops,meanwhile,promoting plant growth and health through hormone production,nutrient regulation,and the suppression of pathogenic microorganisms.Furthermore,endophytic bacteria efficiently degrade PAEs in soil-crop systems through synergistic interactions with indigenous rhizosphere microflora and regulatory effects on enzyme activity in crops.Here,we review the role of endophytic bacteria in the bioremediation of PAEs-contaminated crops and soils.In addition,we discuss the scarcity of endophytic bacterial strains with a confirmed ability to degrade PAEs,and underscore the lack of the research on the mechanisms of PAEs degradation by these bacteria.This review also points out that future study should investigate the molecular mechanisms underlying the interaction between endophytic bacteria and PAEs to offer novel insights and solutions for environmental protection and sustainable agricultural development.
基金supported by the National Natural Science Foundation of China(Grant Nos.51991351 and51903132)the Young Elite Scientist Sponsorship Program by CAST(No.2022QNRC001).
文摘Different reactive flame retardants have been extensively developed for vinyl ester resins(VERs),but very few of them can yield a flame-retardant resin that meets defined standards(e.g.UL-94 V-0 rating).In this work,phosphorous-containing 1-vinylimidazole salts(called VIDHP and VIDPP)were synthesized through the facile neutralization of the acid and 1-vinylimidazole.VIDHP and VIDPP were then applied as flame-retardant crosslinking agents of VERs,by which phosphorus-containing groups could be incorporated into the resin chain via ionic bonds.VIDHP/VER and VIDPP/VER showed a high curing activity and can be well cured in moderate temperatures.With 20 wt.%additions of VIDHP and VIDPP,VIDHP20/VER,and VIDPP20/VER presented a limiting oxygen index value of 29.7%and 28.4%,respectively,with the latter achieving a UL 94 V0 rating.In the cone calorimetric test,compared to the unmodified VERs,VIDPP20/VER exhibited large reductions in the peak heat release rate,total heat release rate,and total smoke release rate while VIDHP20/VER demonstrated comparatively inferior performance in terms of the heat release.VIDHP20/VER and VIDPP20/VER showed good thermal stability and presented a little lower glass transition temperature than the control sample.VIDPP with a low phosphorus oxidation state(+1)demonstrated high flame-retardant activities in the gaseous phase,whereas VIDHP with a high phosphorus oxidation state(+5)primarily exhibited efficacy in the condensed phase.
文摘A new methodology was advanced that mesogenic cores appeared after theformation of urethane groups and during the monomer-to-polymer transition. A newdiphenol monomer, bis(4'-hydroxy-phenyl)-toluene-2 (BHPTU), was obtainedby the reaction of 2,4-tolulene diisocyanate with hydroquinone in dioxane or N,N-dimethyl-acetandde. The reaction process was monitored by FTIR, and the product was investigated bylH NMR and elemental analysis (EA). A liquid crystalline poly(urethane-ester) was obtainedusing the BHPTU monomer.
文摘The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.
文摘A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).
基金the financial support from the Key R&D Projects of Hainan Province(No.ZDYF2024SHFZ065)the Cultivation Research Foundation of Hainan Medical University(No.RZ2300002021 to Dulin Kong,No.RZ2400001591 to Guangkuan Zhao)the Postgraduate Innovation Project of Hainan Medical University(No.HYYB2023A07 to Wenyan Wei)。
文摘An efficient synthesis of α-thioenamine compounds via a K_(2)S_(2)O_(8)-promoted cross-dehydrogenative coupling reaction between heterocyclic thiols and enamine esters in an aqueous medium has been developed.The reaction showed good tolerance for enamine esters and heterocyclic thiols with various functional groups,producingα-thioenamine derivatives in moderate to high yields.Mechanistic studies revealed that heterocyclic thiols react with K_(2)S_(2)O_(8) in water to form reactive disulfides in situ,which then react with enamine esters to generate a series ofα-thioenamines.Building on the proposed mechanism,we developed a sulfenylation reaction of enamine esters with disulfides without the need for an oxidant.This oxidant-free approach has been successfully employed to synthesize DNA-taggedα-thioenamine,demonstrating its considerable potential for various synthetic applications.
