Bridged bicyclic cores have been recognized as valuable bioisosteres of benzene ring,which are of great value in medicinal chemistry.However,the development of fluorinated bicyclic skeletons,which encompass two privil...Bridged bicyclic cores have been recognized as valuable bioisosteres of benzene ring,which are of great value in medicinal chemistry.However,the development of fluorinated bicyclic skeletons,which encompass two privileged elements widely acknowledged for fine tuning the working effect of target molecules,are far less common.Herein,we present a general and practical synthesis of gem-difluorobicyclo[2.1.1]hexanes(diF-BCHs)from readily available difluorinated hexa-1,5-dienes through energy transfer photocatalysis.By taking advantage of an efficient Cope rearrangement,the preparation of both constitutional isomers of diF-BCHs is readily achieved under identical conditions.The operational simplicity,mild conditions and wide scope further highlight the potential application of this protocol.Moreover,computational studies indicated a positive effect of fluorine atoms in lowering either the triplet or FMO energies of the hexa-1,5-diene substrates,thus promoting the present photoinduced[2+2]cycloaddition.展开更多
[Objective]The aim was to explore the active compound of Morus alba leaves with the analysis of active components of hexane extractives of M.alba leaves.[Method]Antibacterial assays of hexane extractives of M.alba lea...[Objective]The aim was to explore the active compound of Morus alba leaves with the analysis of active components of hexane extractives of M.alba leaves.[Method]Antibacterial assays of hexane extractives of M.alba leaves were done and the volatile components of hexane extractives of M.alba leaves with the strongest antibacterial activity were analyzed by gas chromatography-mass spectrometry（GC-MS）.[Result]The results of inhibitory effect of hexane extractives of M.alba leaves on Staphylococcus aureus and Escherichia coli showed that hexane extractives of M.alba leaves collected in June,July and August had antibacterial activity against S.aureus and had no antibacterial effect against E.coli.Furthermore,hexane extractives of M.alba leaves collected in June had the strongest antibacterial activity against S.aureus（inhibition diameter 10.95 mm）.The hexane extractives of M.alba leaves collected in June was analyzed by GC-MS,the main volatile components were tetradecane（16.76%）,dodecane（13.20%）,diisobutyl phthalate（10.26%）,decane（9.10%）,hexadecane（8.71%）,linolenyl alcohol（7.25%）,octadecane（5.88%）,eicosane（3.26%）,dibutyl phthalate（2.59%）.[Conclusion]Linolenyl alcohol was the potential antibacterial compound.展开更多
Objective:To assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis(C.sinensis)against the early fourth instars and female adults of Aedes aegypti(Ae.aegypti).Methods:The lar...Objective:To assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis(C.sinensis)against the early fourth instars and female adults of Aedes aegypti(Ae.aegypti).Methods:The larvicidal potential of the prepared leaf extract was evaluated against early fourth instar larvae of Ae.aegypli using WHO protocol.The mortality counts were made after 24 h and LC_(50)and LG_(50)values were calculated.The efficacy of extract as mosquito irritant was assessed by contact irritancy assays.Extract-impregnated paper was placed on a glass plate over which a perspex funnel with a hole on the top was kept inverted.Single female adult,3-day old unfed/blood-fed,was released inside the funnel.After 3 min of acclimatization time,the time taken for the first take-off and total number of flights undertaken during 15 min were scored.Results:The citrus leaf extracts from hexane possessed moderate larvicidal efficiency against dengue vector.The bioassays resulted in an LC_(50)and LC_(90)value of 446.84 and 1370.96 ppm,respectively after 24 h of exposure.However,the extracts were proved to be remarkable irritant against adults Ae.aegypti,more pronounced effects being observed on blood-fed females than unfed females.The extract-impregnated paper was thus proved to be 7-11 times more irritable as compared with the control paper.Conclusions:The hexane extracts from C.sinensis leaves are proved to be reasonably larvicidal But remarkably irritant against dengue vector.Further studies are needed to identify the possible role of extract as adulticide,oviposition deterrent and ovicidal agent.The isolation of active ingredient from the extract could help in formulating strategies for mosquito control.展开更多
The cracking and aromatization of n hexane over H ZSM 5 modified by various rare earths were investigated by means of continuous flow micro reactor. The surface properties of modified H ZSM 5 catalysts were obta...The cracking and aromatization of n hexane over H ZSM 5 modified by various rare earths were investigated by means of continuous flow micro reactor. The surface properties of modified H ZSM 5 catalysts were obtained from IR, XRD and XPS. The results show that the rare earths enhance the aromatizing properties of the catalysts which are prepared by mechanical mixture method. The results of n hexane cracking and aromatization are correlated with the acidity. The Brnsted acidic sites are the active sites of n hexane aromatization, while Lewis acid site plays an important role in n hexane cracking.展开更多
The coupled reaction of methyl acetate and n‐hexane was carried out over a HZSM‐5 catalyst.In addition to a thermal coupling effect,systematic variations in the product distribution were also observed in the coupled...The coupled reaction of methyl acetate and n‐hexane was carried out over a HZSM‐5 catalyst.In addition to a thermal coupling effect,systematic variations in the product distribution were also observed in the coupled system.The bezene‐toluene‐xylene(BTX)selectivity was remarkably improved while the H2,CO,and CO2 selectivity decreased.Rapid deactivation of the catalyst was observed,caused by the extremely high reactivity of methyl acetate,which was alleviated after adding n‐hexane.These results indicated that a coupling effect exists in this system.A detailed pathway for the coupled system is suggested based on the analysis of the surface species,carbonaceous species deposited on the catalyst,as well as the product selectivity changes.The good match between the"hydrogen deficiency"of methyl acetate and the"hydrogen richness"of n‐hexane is consistent with the observed coupling effect.展开更多
We produce multilayer graphene by the Chemical Vapor Deposition (CVD) method at atmospheric pressure and 1000°C, using flexible copper substrates as catalyst and liquid hexane as the source of carbon. We designed...We produce multilayer graphene by the Chemical Vapor Deposition (CVD) method at atmospheric pressure and 1000°C, using flexible copper substrates as catalyst and liquid hexane as the source of carbon. We designed an optical device to measure the transmittance of the carbon films;with this information we calculate that the approximate number of layers is 11.展开更多
The Henry’s law constant of volatiles in polymer systems is a crucial parameter reflecting the gas-liquid equilibrium,which is very important for devolatilization.In this research,polyolefin elastomer(POE)-cyclohexan...The Henry’s law constant of volatiles in polymer systems is a crucial parameter reflecting the gas-liquid equilibrium,which is very important for devolatilization.In this research,polyolefin elastomer(POE)-cyclohexane and polydimethylsiloxane(PDMS)-hexane systems were studied,and the Henry’s law constant was obtained by measuring the gas phase equilibrium partial pressure when polymer solutions containing different mass fractions of volatiles reached a saturated state.The effects of temperature,type of volatiles,and polymer viscosity on the gas phase equilibrium partial pressure and Henry’s law constant of the volatiles were investigated.The results indicate that,with the increase of temperature and polymer viscosity,the gas phase equilibrium partial pressure and Henry’s law constant of volatiles increase.As temperature increases,the solubility of gas in liquid decreases.The relationship between the Henry’s law constant and temperature is consistent with the Arrhenius law.In the PDMS-hexane system,the gas phase equilibrium partial pressure and Henry’s law constant of n-hexane are higher than those of cyclohexane.The obtained Henry’s law constants can be used as a reference for perfecting the devolatilization process and improving the devolatilization effect.展开更多
Dibranched hexane isomers,particularly 2,3-dimethylbutane(23DMB),are of great significance in upgrading gasoline to high octane numbers.Yet,the separation of 23DMB from 2,2-dimethylbutane(22DMB)has remained challengin...Dibranched hexane isomers,particularly 2,3-dimethylbutane(23DMB),are of great significance in upgrading gasoline to high octane numbers.Yet,the separation of 23DMB from 2,2-dimethylbutane(22DMB)has remained challenging,mainly due to their nearly identical kinetic diameters(23DMB:6.2Å,22DMB:6.3Å).Herein,we report a channelpore interconnected metal–organic framework(named JNU-2)exhibiting complete exclusion of 22DMB thanks to a limited opening at the channelpore junction,while exceptionally high adsorption for n-hexane(nHEX),2-methylpentane(2MP),3-methylpentane(3MP),and 23DMB due to the connecting large pores.Further adsorption kinetics studies reveal that the diffusion coefficient of 23DMB in JNU-2 is significantly lower than those of nHEX,2MP,and 3MP.This difference in diffusion coefficients allowed us to successfully demonstrate the stepwise splitting of hexanes on JNU-2 through column breakthrough experiments.Specifically,a kinetically controlled separation of dibranched hexanes(22DMB and 23DMB)from their linear(nHEX)and monobranched isomers(2MP and 3MP),followed by a thermodynamically controlled sieving of 22DMB from 23DMB.This work presents a robust porous material for its versatility in the separation of hexane isomers by reconciling adsorption kinetics and thermodynamics.Notably,our study represents the first reported material with the ability to separate 22DMB and 23DMB.展开更多
Alkane isomers(mainly C5-C7 alkanes),produced via catalytic isomerization reactions during oil refinement,are important raw chemicals in the petrochemical industry[1].They are used in a broad spectrum of chemical proc...Alkane isomers(mainly C5-C7 alkanes),produced via catalytic isomerization reactions during oil refinement,are important raw chemicals in the petrochemical industry[1].They are used in a broad spectrum of chemical processes,depending on their branching.Specifically,normal alkanes and monobranched isomers are premium ethylene feed,and dibranched isomers are desired components for high-rating gasolines[2].Consequently,the isomers must be separated before further use.展开更多
Aluminum-based metal-organic frameworks(Al-MOFs)feature low density,high stability,and non-toxicity,making them highly promising for adsorption-related applications.In this study,we report the construction of a novel ...Aluminum-based metal-organic frameworks(Al-MOFs)feature low density,high stability,and non-toxicity,making them highly promising for adsorption-related applications.In this study,we report the construction of a novel nia-type Al-MOF based on 6-connected trinuclear Al3 clusters,HIAM-341,employing an isophthalate-derived hexatopic linker.It exhibits a robust structure with a BET surface area of 1094 m^(2)·g^(–1),with a pore size of 4.7A.HIAM-341 demonstrates size-sieving separation of hexane isomers,with adsorption capacities of 164 and 54 mg·g^(-1) for n-hexane and 3-methylpentane at 303 K and 1 bar,respectively,while excluding 2,2-dimethylbutane.Multicomponent breakthrough experiments further confirm its separation capability,and the underlying selective molecular exclusion mechanism has been uncovered by DFT calculations.Our research provides new insights into the rational design of robust Al-MOFs with tailored pore structures by employing organic linkers with high coordination density for targeted separations.展开更多
The separation of hexane isomers is of vital importance to produce high quality gasoline in the petrochemical industry.However,the similar vapor pressure and boiling point of hexane isomers bring great difficulties an...The separation of hexane isomers is of vital importance to produce high quality gasoline in the petrochemical industry.However,the similar vapor pressure and boiling point of hexane isomers bring great difficulties and challenges in the separation process.Sieving effect,which allowing smaller molecules pass through and preventing others,should be a powerful strategy to solve this problem by making good use of porous materials.Therefore,physical separation by metal-organic framework(MOF)materials appears and becomes a burgeoning separation technique in industry.Due to the weak interaction between hexane isomers with absorbents,it puts forward higher requirements for the accurate design of MOF materials with optimal pore system.To address this issue,a novel MOF[Zn_(9)(tba)_(9)(dabco)_(3)]·12DMA-6MeOH(abbreviation:Zn_(9)(tba)_(9)(dabco)_(3);H_(2)tba=4-(1H-tetrazol-5-yl)-benzoic acid;dabco=1,4-diazabicyclo[2.2.2]octane;DMA=N,N-dimethylacetamide)with bcu network has been designed and synthesized by reticular chemistry strategy.Benefiting from the pre-designed topology and suitable linear ligand H_(2)tba and dabco,the structure of Zn_(9)(tba)_(9)(dabco)_(3)exhibits two types of channels with triangular-like and quadrilateral-like geometry.Zn_(9)(tba)_(9)(dabco)_(3)with appropriate channel size and shape displays potential selective adsorption capacity of vapor-phase hexane isomers through sieving effect.Moreover,outstanding gas adsorptive separation properties of Zn_(9)(tba)_(9)(dabco)_(3)could also be speculated by theoretical ideal adsorbed solution theory(IAST),suggesting Zn_(9)(tba)_(9)(dabco)_(3)can be regarded as a potential adsorbent material for purification natural gas_Breakthrough experiments show that Zn_(9)(tba)_(9)(dabco)_(3)is capable of discriminating all four hexane isomers at 298 K,and the corresponding research octane number(RON)of the eluted mixture closes to 95,which is higher than the standard for industrially refined hexane blends(about 83).We speculate that sieving effect and diffusion are a synergetic contributory factor in their elution dynamics,which may be ascribed to temperature-dependent interaction between pore aperture and each isomer.This work presents a typical example for design of efficient MOF absorbents by reticular chemistry strategy.展开更多
Ultrathin zeolite membranes are of paramount importance in accelerating gas transport during membrane separation,and lowering down their membrane thicknesses to submicron scale is deemed to be very challenging.Herein,...Ultrathin zeolite membranes are of paramount importance in accelerating gas transport during membrane separation,and lowering down their membrane thicknesses to submicron scale is deemed to be very challenging.Herein,we develop an advanced approach of surface gel conversion for synthesis of submicron-thick pure silica MFI(silicalite-1)zeolite membranes.Viscous gel is prepared by finely adjusting the precursor composition,enabling its reduced wettability.The unfavorable wetting of the support surface can effectively prevent gel penetration into alumina support voids.Aided by the seeds,the surface gel is directly and fully crystallized into an MFI zeolite membrane with minimal water steam.A membrane with a thickness of 500 nm is successfully acquired and it is free of visible cracks.Additionally,the as-synthesized membranes exhibit rapid and selective separation of hexane isomers by virtue of unprecedentedly high n-hexane permeance of 24.5×10^−7 mol m^−2 s^−1 Pa^−1 and impressive separation factors of 13.3-22.6 for n-hexane over its isomers.This developed approach is of practical interest for sustainable synthesis of high-quality zeolite membranes.展开更多
Main observation and conclusion A facile synthetic method for the construction of 3-azabicyclo[3.1.0]hexane in the presence of copper catalyst system was developed.The reaction proceeds through Michael addition of all...Main observation and conclusion A facile synthetic method for the construction of 3-azabicyclo[3.1.0]hexane in the presence of copper catalyst system was developed.The reaction proceeds through Michael addition of allylamines with allenes followed by copper-mediated intramolecular oxidative carbanion 5-exo-trig radical cyclization,affording potential biologically active 3-azabicyclo[3.1.O]hexane derivatives in moderate to high yields(42%-85%).展开更多
The photodegradation of 4-chlorobiphenyl in hexane by UV irradiation has been investigated. For the first time, the UV spectral changes of 4-chlorobiphenyl and formation of chloride in the photoreaction have been disc...The photodegradation of 4-chlorobiphenyl in hexane by UV irradiation has been investigated. For the first time, the UV spectral changes of 4-chlorobiphenyl and formation of chloride in the photoreaction have been discussed. The main pathway for the degradation of 4-chlorobiphenyl in hexane was dechlorination to follow a ftrst order kinetics. The products were formed by the cleavage of carbon-chlorine bond to produce a biphenyl free radical, which then abstracted hydrogen from the solvent hexane to form biphenyl. With irradiation, biphenyl was also decomposed to lower hydrocarbons as the final products, which was further confirmed by the degradation experiment of biphenyl.展开更多
Porous organic polymers are remarkably versatile materials with porous and carefully designed structures.They complement traditional preservation methods by overcoming their limitations and significantly extending the...Porous organic polymers are remarkably versatile materials with porous and carefully designed structures.They complement traditional preservation methods by overcoming their limitations and significantly extending the shelf life of preserved products.Notably,porous hollow nanospheres(PHNs),with their unique hollow structures capable of adsorbing and releasing organic molecules,have garnered considerable attention in food preservation.However,most PHNs are challenging to synthesize in one step,and PHNs are usually in powder form,which makes it challenging to apply them directly.In this study,we successfully synthesized PHNs in one step using the Friedel–Crafts reaction.The PHNs,adsorbed with hexanal molecules,were then embedded in polymer fibers to create composites via electrospinning.The preservation effect of the composite nanofiber membranes was investigated by determining the changes in appearance,weight,peel hardness,and pulp sugar content of three fruits,namely strawberries,bananas,and kumquats,after several days of storage.In comparison to pure poly(ε-caprolactone)fiber membranes,PHNs containing hexanal molecules slowed down the oxidative deterioration process and enhanced the quality and flavor of preserved fruits.This research presents innovative approaches for using porous organic polymers in food preservation and serves as a valuable reference for the development of future food packaging materials.展开更多
Immobilization techniques and biocatalytic transformations performed in organic media are new developing methods for organic reactions. Baker's yeast was immobilized on the alginate supports. This preparation cont...Immobilization techniques and biocatalytic transformations performed in organic media are new developing methods for organic reactions. Baker's yeast was immobilized on the alginate supports. This preparation contained about 20% of dry yeast cells. The immobilized Baker's yeast were found to be very effective in the reduction of o-benzoquinone, p-benzoquinones, naphthoquinones, and anthraquinones in hexane.展开更多
It is well known that gas oils from oilsands bitumen are difficult to hydrotreat. In order to develop the most appropriate flow sheet and operating conditions, a thorough knowledge of the molecular structure and beha...It is well known that gas oils from oilsands bitumen are difficult to hydrotreat. In order to develop the most appropriate flow sheet and operating conditions, a thorough knowledge of the molecular structure and behaviour of bitumen and its gas oil products is needed. In this work, the gas oil samples are fractionated in an attempt to isolate and identify the problematic molecular species for hydrotreating. It is found that the major nitrogen sources in coker gas oils are associated with relatively small pentane insoluble species and an even smaller, highly polar, hexane insoluble species. Structural information obtained for these fractions indicates that they are formed during the cracking of resin molecules. Nitrogen speciation shows that the pyrroles are the primary nitrogen type, with pyridines also being an important species. Both nitrogen species are undesirable in the hydrotreating process. Pyrroles in particular are subject to polymerisation, producing gums and sediments that foul filters and other equipment while pyridines can directly deactivate the hydrotreating catalyst.展开更多
Two new Cu（Ⅱ） coordination polymers, [Cu2（tbph）2（btb）2]n （1） and {[Cu2（tbph）2- （bth）2]·H2O}n （2）, （H2tbph = 4-tert-butyl-phthalic acid, btb = 1,4-bis（1,2,4-triazol-1- yl）butane, bth = 1,6-bis（1...Two new Cu（Ⅱ） coordination polymers, [Cu2（tbph）2（btb）2]n （1） and {[Cu2（tbph）2- （bth）2]·H2O}n （2）, （H2tbph = 4-tert-butyl-phthalic acid, btb = 1,4-bis（1,2,4-triazol-1- yl）butane, bth = 1,6-bis（1,2,4-triazol-l-yl）hexane）, have been synthesized and characterized by elemental analysis, FT-IR and X-ray single-crystal diffraction. Complex 1 has a 2D sql layer. Complex 2 shows a （3,4）-connected 2D sheet with a （4.6^4.8）（4.8^2） topology. The thermal behavior of the two cor- responding complexes has briefly been investigated.展开更多
This study aimed to conduct measurement uncertainty assessment of a new method for determination of Sudan colorants（Sudan Ⅰ, Ⅱ, Ⅲ and Ⅳ） in food by high performance liquid chromatography（HPLC）. Samples were ex...This study aimed to conduct measurement uncertainty assessment of a new method for determination of Sudan colorants（Sudan Ⅰ, Ⅱ, Ⅲ and Ⅳ） in food by high performance liquid chromatography（HPLC）. Samples were extracted with organic solvents（hexane, 20% acetone） and first purified by magnesium trisilicate（2Mg O·3Si O2）. The Sudan colorants（Sudan Ⅰ–Ⅳ） were also initially separated on C8 by gradient elution using acetonitrile and 0.1%（v/v） formic acid aqueous solution as the mobile phases and detected with diode-array detector（DAD）. The uncertainty of mathematical model of Sudan Ⅰ, Ⅱ, Ⅲ, Ⅳ is based on EURACHEM guidelines. The sources and components of uncertainty were calculated. The experiment gave a good linear relationship over the concentration from 0.4 to 4.0 μg/m L and spiked recoveries were from 74.0% to 97.5%. The limits of determination（LOD） were 48, 61, 36, 58 μg/kg for the four analytes, respectively. The total uncertainty of Sudan colorants（Sudan Ⅰ, Ⅱ, Ⅲ and Ⅳ） was 810±30.8, 790±28.4, 750±27.0, 730±50.0 μg/kg, respectively. The recovery uncertainty was the most significant factor contributing to the total uncertainty. The developed method is simple, rapid, and highly sensitive. It can be used for the determination of trace Sudan dyes in food samples. The sources of uncertainty have been identified and uncertainty components have been simplified and considered.展开更多
Cucurbituril has a high symmetry and rigid structure.When cucurbit[6]uril（CB[6]） was nitrolyzed with the mixed solution of acetic anhydride in fuming nitric acid,nitroform（NF） was generated.NF also can be obtained...Cucurbituril has a high symmetry and rigid structure.When cucurbit[6]uril（CB[6]） was nitrolyzed with the mixed solution of acetic anhydride in fuming nitric acid,nitroform（NF） was generated.NF also can be obtained by the nitration of both CB[5,7,8].This nitration procedure provides a lower risk,inexpensive,new preparation of nitroform,and the reaction condition of this new method is very mild.展开更多
基金the National Natural Science Foundation of China(No.22271151)the Distinguished Youth Foundation of Jiangsu Province.
文摘Bridged bicyclic cores have been recognized as valuable bioisosteres of benzene ring,which are of great value in medicinal chemistry.However,the development of fluorinated bicyclic skeletons,which encompass two privileged elements widely acknowledged for fine tuning the working effect of target molecules,are far less common.Herein,we present a general and practical synthesis of gem-difluorobicyclo[2.1.1]hexanes(diF-BCHs)from readily available difluorinated hexa-1,5-dienes through energy transfer photocatalysis.By taking advantage of an efficient Cope rearrangement,the preparation of both constitutional isomers of diF-BCHs is readily achieved under identical conditions.The operational simplicity,mild conditions and wide scope further highlight the potential application of this protocol.Moreover,computational studies indicated a positive effect of fluorine atoms in lowering either the triplet or FMO energies of the hexa-1,5-diene substrates,thus promoting the present photoinduced[2+2]cycloaddition.
基金Supported by the Forestry Department of Heilongjiang Province Science and Technology Promotion Project(01043208003)the Project of Science and Technology Department of Heilongjiang Province(LC07C27)~~
文摘[Objective]The aim was to explore the active compound of Morus alba leaves with the analysis of active components of hexane extractives of M.alba leaves.[Method]Antibacterial assays of hexane extractives of M.alba leaves were done and the volatile components of hexane extractives of M.alba leaves with the strongest antibacterial activity were analyzed by gas chromatography-mass spectrometry（GC-MS）.[Result]The results of inhibitory effect of hexane extractives of M.alba leaves on Staphylococcus aureus and Escherichia coli showed that hexane extractives of M.alba leaves collected in June,July and August had antibacterial activity against S.aureus and had no antibacterial effect against E.coli.Furthermore,hexane extractives of M.alba leaves collected in June had the strongest antibacterial activity against S.aureus（inhibition diameter 10.95 mm）.The hexane extractives of M.alba leaves collected in June was analyzed by GC-MS,the main volatile components were tetradecane（16.76%）,dodecane（13.20%）,diisobutyl phthalate（10.26%）,decane（9.10%）,hexadecane（8.71%）,linolenyl alcohol（7.25%）,octadecane（5.88%）,eicosane（3.26%）,dibutyl phthalate（2.59%）.[Conclusion]Linolenyl alcohol was the potential antibacterial compound.
基金supported by University Grants Commission[grant No.F.35-74/2009(SR)]
文摘Objective:To assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis(C.sinensis)against the early fourth instars and female adults of Aedes aegypti(Ae.aegypti).Methods:The larvicidal potential of the prepared leaf extract was evaluated against early fourth instar larvae of Ae.aegypli using WHO protocol.The mortality counts were made after 24 h and LC_(50)and LG_(50)values were calculated.The efficacy of extract as mosquito irritant was assessed by contact irritancy assays.Extract-impregnated paper was placed on a glass plate over which a perspex funnel with a hole on the top was kept inverted.Single female adult,3-day old unfed/blood-fed,was released inside the funnel.After 3 min of acclimatization time,the time taken for the first take-off and total number of flights undertaken during 15 min were scored.Results:The citrus leaf extracts from hexane possessed moderate larvicidal efficiency against dengue vector.The bioassays resulted in an LC_(50)and LC_(90)value of 446.84 and 1370.96 ppm,respectively after 24 h of exposure.However,the extracts were proved to be remarkable irritant against adults Ae.aegypti,more pronounced effects being observed on blood-fed females than unfed females.The extract-impregnated paper was thus proved to be 7-11 times more irritable as compared with the control paper.Conclusions:The hexane extracts from C.sinensis leaves are proved to be reasonably larvicidal But remarkably irritant against dengue vector.Further studies are needed to identify the possible role of extract as adulticide,oviposition deterrent and ovicidal agent.The isolation of active ingredient from the extract could help in formulating strategies for mosquito control.
文摘The cracking and aromatization of n hexane over H ZSM 5 modified by various rare earths were investigated by means of continuous flow micro reactor. The surface properties of modified H ZSM 5 catalysts were obtained from IR, XRD and XPS. The results show that the rare earths enhance the aromatizing properties of the catalysts which are prepared by mechanical mixture method. The results of n hexane cracking and aromatization are correlated with the acidity. The Brnsted acidic sites are the active sites of n hexane aromatization, while Lewis acid site plays an important role in n hexane cracking.
文摘The coupled reaction of methyl acetate and n‐hexane was carried out over a HZSM‐5 catalyst.In addition to a thermal coupling effect,systematic variations in the product distribution were also observed in the coupled system.The bezene‐toluene‐xylene(BTX)selectivity was remarkably improved while the H2,CO,and CO2 selectivity decreased.Rapid deactivation of the catalyst was observed,caused by the extremely high reactivity of methyl acetate,which was alleviated after adding n‐hexane.These results indicated that a coupling effect exists in this system.A detailed pathway for the coupled system is suggested based on the analysis of the surface species,carbonaceous species deposited on the catalyst,as well as the product selectivity changes.The good match between the"hydrogen deficiency"of methyl acetate and the"hydrogen richness"of n‐hexane is consistent with the observed coupling effect.
文摘We produce multilayer graphene by the Chemical Vapor Deposition (CVD) method at atmospheric pressure and 1000°C, using flexible copper substrates as catalyst and liquid hexane as the source of carbon. We designed an optical device to measure the transmittance of the carbon films;with this information we calculate that the approximate number of layers is 11.
基金Polyolefin Elastomer Technology Development project(2020B-2619).
文摘The Henry’s law constant of volatiles in polymer systems is a crucial parameter reflecting the gas-liquid equilibrium,which is very important for devolatilization.In this research,polyolefin elastomer(POE)-cyclohexane and polydimethylsiloxane(PDMS)-hexane systems were studied,and the Henry’s law constant was obtained by measuring the gas phase equilibrium partial pressure when polymer solutions containing different mass fractions of volatiles reached a saturated state.The effects of temperature,type of volatiles,and polymer viscosity on the gas phase equilibrium partial pressure and Henry’s law constant of the volatiles were investigated.The results indicate that,with the increase of temperature and polymer viscosity,the gas phase equilibrium partial pressure and Henry’s law constant of volatiles increase.As temperature increases,the solubility of gas in liquid decreases.The relationship between the Henry’s law constant and temperature is consistent with the Arrhenius law.In the PDMS-hexane system,the gas phase equilibrium partial pressure and Henry’s law constant of n-hexane are higher than those of cyclohexane.The obtained Henry’s law constants can be used as a reference for perfecting the devolatilization process and improving the devolatilization effect.
基金supported by the National Natural Science Foundation of China(grant nos.21731002,21975104,22150004,22301102,and 22271120)Guangdong Basic and Applied Basic Research Foundation(grant nos.2023A1515010952 and 2024A1515012434)National Postdoctoral Program for Innovative Talents(grant no.BX20220132).
文摘Dibranched hexane isomers,particularly 2,3-dimethylbutane(23DMB),are of great significance in upgrading gasoline to high octane numbers.Yet,the separation of 23DMB from 2,2-dimethylbutane(22DMB)has remained challenging,mainly due to their nearly identical kinetic diameters(23DMB:6.2Å,22DMB:6.3Å).Herein,we report a channelpore interconnected metal–organic framework(named JNU-2)exhibiting complete exclusion of 22DMB thanks to a limited opening at the channelpore junction,while exceptionally high adsorption for n-hexane(nHEX),2-methylpentane(2MP),3-methylpentane(3MP),and 23DMB due to the connecting large pores.Further adsorption kinetics studies reveal that the diffusion coefficient of 23DMB in JNU-2 is significantly lower than those of nHEX,2MP,and 3MP.This difference in diffusion coefficients allowed us to successfully demonstrate the stepwise splitting of hexanes on JNU-2 through column breakthrough experiments.Specifically,a kinetically controlled separation of dibranched hexanes(22DMB and 23DMB)from their linear(nHEX)and monobranched isomers(2MP and 3MP),followed by a thermodynamically controlled sieving of 22DMB from 23DMB.This work presents a robust porous material for its versatility in the separation of hexane isomers by reconciling adsorption kinetics and thermodynamics.Notably,our study represents the first reported material with the ability to separate 22DMB and 23DMB.
基金supported by the Key Program of National Natural Science Foundation of China(22438001)the National Natural Science Foundation of China(22478251,52373212)+1 种基金the Shenzhen Science and Technology Program(KCXFZ20211020163818026)the Shenzhen Polytechnic University Research Fund(6024310024K)。
文摘Alkane isomers(mainly C5-C7 alkanes),produced via catalytic isomerization reactions during oil refinement,are important raw chemicals in the petrochemical industry[1].They are used in a broad spectrum of chemical processes,depending on their branching.Specifically,normal alkanes and monobranched isomers are premium ethylene feed,and dibranched isomers are desired components for high-rating gasolines[2].Consequently,the isomers must be separated before further use.
基金the National Natural Science Foundation of China(22478251)Shenzhen Polytechnic University Research Fund(Nos.6024310024K,6022312041K)the Post-doctoral Later-stage Foundation Project of Shenzhen Poly-technic(Project No.6021271010K)for financial support.
文摘Aluminum-based metal-organic frameworks(Al-MOFs)feature low density,high stability,and non-toxicity,making them highly promising for adsorption-related applications.In this study,we report the construction of a novel nia-type Al-MOF based on 6-connected trinuclear Al3 clusters,HIAM-341,employing an isophthalate-derived hexatopic linker.It exhibits a robust structure with a BET surface area of 1094 m^(2)·g^(–1),with a pore size of 4.7A.HIAM-341 demonstrates size-sieving separation of hexane isomers,with adsorption capacities of 164 and 54 mg·g^(-1) for n-hexane and 3-methylpentane at 303 K and 1 bar,respectively,while excluding 2,2-dimethylbutane.Multicomponent breakthrough experiments further confirm its separation capability,and the underlying selective molecular exclusion mechanism has been uncovered by DFT calculations.Our research provides new insights into the rational design of robust Al-MOFs with tailored pore structures by employing organic linkers with high coordination density for targeted separations.
基金the National Natural Science Foundation of China(Nos.21771078,21621001)the 111 Project(No.B17020)+1 种基金the National Key Research and Development Program of China(No.2016YFB0701100)Zhejiang Provincial Natural Science Foundation of China(No.LQ18B010002).
文摘The separation of hexane isomers is of vital importance to produce high quality gasoline in the petrochemical industry.However,the similar vapor pressure and boiling point of hexane isomers bring great difficulties and challenges in the separation process.Sieving effect,which allowing smaller molecules pass through and preventing others,should be a powerful strategy to solve this problem by making good use of porous materials.Therefore,physical separation by metal-organic framework(MOF)materials appears and becomes a burgeoning separation technique in industry.Due to the weak interaction between hexane isomers with absorbents,it puts forward higher requirements for the accurate design of MOF materials with optimal pore system.To address this issue,a novel MOF[Zn_(9)(tba)_(9)(dabco)_(3)]·12DMA-6MeOH(abbreviation:Zn_(9)(tba)_(9)(dabco)_(3);H_(2)tba=4-(1H-tetrazol-5-yl)-benzoic acid;dabco=1,4-diazabicyclo[2.2.2]octane;DMA=N,N-dimethylacetamide)with bcu network has been designed and synthesized by reticular chemistry strategy.Benefiting from the pre-designed topology and suitable linear ligand H_(2)tba and dabco,the structure of Zn_(9)(tba)_(9)(dabco)_(3)exhibits two types of channels with triangular-like and quadrilateral-like geometry.Zn_(9)(tba)_(9)(dabco)_(3)with appropriate channel size and shape displays potential selective adsorption capacity of vapor-phase hexane isomers through sieving effect.Moreover,outstanding gas adsorptive separation properties of Zn_(9)(tba)_(9)(dabco)_(3)could also be speculated by theoretical ideal adsorbed solution theory(IAST),suggesting Zn_(9)(tba)_(9)(dabco)_(3)can be regarded as a potential adsorbent material for purification natural gas_Breakthrough experiments show that Zn_(9)(tba)_(9)(dabco)_(3)is capable of discriminating all four hexane isomers at 298 K,and the corresponding research octane number(RON)of the eluted mixture closes to 95,which is higher than the standard for industrially refined hexane blends(about 83).We speculate that sieving effect and diffusion are a synergetic contributory factor in their elution dynamics,which may be ascribed to temperature-dependent interaction between pore aperture and each isomer.This work presents a typical example for design of efficient MOF absorbents by reticular chemistry strategy.
基金the National Natural Science Foundation of China(21531003,21501024 and 21971035)Jilin Scientific and Technological Development Program(20170101198JC and 20190103017JH)+2 种基金Jilin Education Office(JJKH20180015KJ)“111”Program(B18012)open projects from the State Key Laboratory of Inorganic Synthesis&Preparative Chemistry and State Key Laboratory of Heavy Oil Processing(2018-8,SKLOP201902003)。
文摘Ultrathin zeolite membranes are of paramount importance in accelerating gas transport during membrane separation,and lowering down their membrane thicknesses to submicron scale is deemed to be very challenging.Herein,we develop an advanced approach of surface gel conversion for synthesis of submicron-thick pure silica MFI(silicalite-1)zeolite membranes.Viscous gel is prepared by finely adjusting the precursor composition,enabling its reduced wettability.The unfavorable wetting of the support surface can effectively prevent gel penetration into alumina support voids.Aided by the seeds,the surface gel is directly and fully crystallized into an MFI zeolite membrane with minimal water steam.A membrane with a thickness of 500 nm is successfully acquired and it is free of visible cracks.Additionally,the as-synthesized membranes exhibit rapid and selective separation of hexane isomers by virtue of unprecedentedly high n-hexane permeance of 24.5×10^−7 mol m^−2 s^−1 Pa^−1 and impressive separation factors of 13.3-22.6 for n-hexane over its isomers.This developed approach is of practical interest for sustainable synthesis of high-quality zeolite membranes.
基金the Shanghai Comittee of Science and Technology(No.17ZR1407600)。
文摘Main observation and conclusion A facile synthetic method for the construction of 3-azabicyclo[3.1.0]hexane in the presence of copper catalyst system was developed.The reaction proceeds through Michael addition of allylamines with allenes followed by copper-mediated intramolecular oxidative carbanion 5-exo-trig radical cyclization,affording potential biologically active 3-azabicyclo[3.1.O]hexane derivatives in moderate to high yields(42%-85%).
基金Project supported by the National Natural Science Foundation of China （No. 2003CB415007） and the Ministry of Education of China （No. 20030027008）.
文摘The photodegradation of 4-chlorobiphenyl in hexane by UV irradiation has been investigated. For the first time, the UV spectral changes of 4-chlorobiphenyl and formation of chloride in the photoreaction have been discussed. The main pathway for the degradation of 4-chlorobiphenyl in hexane was dechlorination to follow a ftrst order kinetics. The products were formed by the cleavage of carbon-chlorine bond to produce a biphenyl free radical, which then abstracted hydrogen from the solvent hexane to form biphenyl. With irradiation, biphenyl was also decomposed to lower hydrocarbons as the final products, which was further confirmed by the degradation experiment of biphenyl.
文摘Porous organic polymers are remarkably versatile materials with porous and carefully designed structures.They complement traditional preservation methods by overcoming their limitations and significantly extending the shelf life of preserved products.Notably,porous hollow nanospheres(PHNs),with their unique hollow structures capable of adsorbing and releasing organic molecules,have garnered considerable attention in food preservation.However,most PHNs are challenging to synthesize in one step,and PHNs are usually in powder form,which makes it challenging to apply them directly.In this study,we successfully synthesized PHNs in one step using the Friedel–Crafts reaction.The PHNs,adsorbed with hexanal molecules,were then embedded in polymer fibers to create composites via electrospinning.The preservation effect of the composite nanofiber membranes was investigated by determining the changes in appearance,weight,peel hardness,and pulp sugar content of three fruits,namely strawberries,bananas,and kumquats,after several days of storage.In comparison to pure poly(ε-caprolactone)fiber membranes,PHNs containing hexanal molecules slowed down the oxidative deterioration process and enhanced the quality and flavor of preserved fruits.This research presents innovative approaches for using porous organic polymers in food preservation and serves as a valuable reference for the development of future food packaging materials.
基金Project supported by the National Natural Science Foundation of China and the Guangdong Science Foundation of Guangdong Province.
文摘Immobilization techniques and biocatalytic transformations performed in organic media are new developing methods for organic reactions. Baker's yeast was immobilized on the alginate supports. This preparation contained about 20% of dry yeast cells. The immobilized Baker's yeast were found to be very effective in the reduction of o-benzoquinone, p-benzoquinones, naphthoquinones, and anthraquinones in hexane.
文摘It is well known that gas oils from oilsands bitumen are difficult to hydrotreat. In order to develop the most appropriate flow sheet and operating conditions, a thorough knowledge of the molecular structure and behaviour of bitumen and its gas oil products is needed. In this work, the gas oil samples are fractionated in an attempt to isolate and identify the problematic molecular species for hydrotreating. It is found that the major nitrogen sources in coker gas oils are associated with relatively small pentane insoluble species and an even smaller, highly polar, hexane insoluble species. Structural information obtained for these fractions indicates that they are formed during the cracking of resin molecules. Nitrogen speciation shows that the pyrroles are the primary nitrogen type, with pyridines also being an important species. Both nitrogen species are undesirable in the hydrotreating process. Pyrroles in particular are subject to polymerisation, producing gums and sediments that foul filters and other equipment while pyridines can directly deactivate the hydrotreating catalyst.
基金Supported financially by Henan Province basic and frontier technology research projects of Henan Provincial Department of Science and Technology(No.142300410083)
文摘Two new Cu（Ⅱ） coordination polymers, [Cu2（tbph）2（btb）2]n （1） and {[Cu2（tbph）2- （bth）2]·H2O}n （2）, （H2tbph = 4-tert-butyl-phthalic acid, btb = 1,4-bis（1,2,4-triazol-1- yl）butane, bth = 1,6-bis（1,2,4-triazol-l-yl）hexane）, have been synthesized and characterized by elemental analysis, FT-IR and X-ray single-crystal diffraction. Complex 1 has a 2D sql layer. Complex 2 shows a （3,4）-connected 2D sheet with a （4.6^4.8）（4.8^2） topology. The thermal behavior of the two cor- responding complexes has briefly been investigated.
基金supported by grants from Non-profit Projects of Ministry of Environmental Protection of the People’s Republic of China(No.201309044)the Foundation for Excellent Young Talents of Hubei Center for Disease Control and Prevention,and the Foundation for Medical Leading Personnel of Hubei Province
文摘This study aimed to conduct measurement uncertainty assessment of a new method for determination of Sudan colorants（Sudan Ⅰ, Ⅱ, Ⅲ and Ⅳ） in food by high performance liquid chromatography（HPLC）. Samples were extracted with organic solvents（hexane, 20% acetone） and first purified by magnesium trisilicate（2Mg O·3Si O2）. The Sudan colorants（Sudan Ⅰ–Ⅳ） were also initially separated on C8 by gradient elution using acetonitrile and 0.1%（v/v） formic acid aqueous solution as the mobile phases and detected with diode-array detector（DAD）. The uncertainty of mathematical model of Sudan Ⅰ, Ⅱ, Ⅲ, Ⅳ is based on EURACHEM guidelines. The sources and components of uncertainty were calculated. The experiment gave a good linear relationship over the concentration from 0.4 to 4.0 μg/m L and spiked recoveries were from 74.0% to 97.5%. The limits of determination（LOD） were 48, 61, 36, 58 μg/kg for the four analytes, respectively. The total uncertainty of Sudan colorants（Sudan Ⅰ, Ⅱ, Ⅲ and Ⅳ） was 810±30.8, 790±28.4, 750±27.0, 730±50.0 μg/kg, respectively. The recovery uncertainty was the most significant factor contributing to the total uncertainty. The developed method is simple, rapid, and highly sensitive. It can be used for the determination of trace Sudan dyes in food samples. The sources of uncertainty have been identified and uncertainty components have been simplified and considered.
基金supported by the grant of Beijing Institute of Technology
文摘Cucurbituril has a high symmetry and rigid structure.When cucurbit[6]uril（CB[6]） was nitrolyzed with the mixed solution of acetic anhydride in fuming nitric acid,nitroform（NF） was generated.NF also can be obtained by the nitration of both CB[5,7,8].This nitration procedure provides a lower risk,inexpensive,new preparation of nitroform,and the reaction condition of this new method is very mild.
