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2007 Volume 24 Issue 4
2007, 24(4): 365-369
Abstract:
Hexaazatriphenylene derivatives were designed and synthesized by introducing methoxyphenyl or fluorenyl peripheral aryl substituents,and the effect of these aromatic substituents on their optical properties and bandgap were characterized by means of UV-Vis absorption spectroscopy,fluorescence spectroscopy and electrochemical cyclic voltammogram.The introduction of methoxyphenyl or fluorenyl endows significantly enhanced electron-accepting capability,and the LUMO energy level decreases from -3.50 eV of 1a to -3.68 eV of 1b and -3.66 eV of 1c.Meanwhile,both the absorption and the fluorescence spectra have an obvious red shift.The absorption/emission maxima are red-shifted from 413/432 nm of 1a to 460/543 nm of 1b and 479/552 nm of 1c.Furthermore,the introduction of bulky aromatic substituents effectively depresses the fluorescence quenching,and the fluorescence quantum yield increases from 0.23 of 1a to 0.81 of 1b and 0.87 of 1c.
Hexaazatriphenylene derivatives were designed and synthesized by introducing methoxyphenyl or fluorenyl peripheral aryl substituents,and the effect of these aromatic substituents on their optical properties and bandgap were characterized by means of UV-Vis absorption spectroscopy,fluorescence spectroscopy and electrochemical cyclic voltammogram.The introduction of methoxyphenyl or fluorenyl endows significantly enhanced electron-accepting capability,and the LUMO energy level decreases from -3.50 eV of 1a to -3.68 eV of 1b and -3.66 eV of 1c.Meanwhile,both the absorption and the fluorescence spectra have an obvious red shift.The absorption/emission maxima are red-shifted from 413/432 nm of 1a to 460/543 nm of 1b and 479/552 nm of 1c.Furthermore,the introduction of bulky aromatic substituents effectively depresses the fluorescence quenching,and the fluorescence quantum yield increases from 0.23 of 1a to 0.81 of 1b and 0.87 of 1c.
2007, 24(4): 370-373
Abstract:
Neonicotinoid-insecticides are the inhibitors of insect nAChRs with higher herbicidal activity,higher degree of selectivity,and excellent environmental safety.Based on the relationship between structure and activity of nitromethylene heterocycle compounds,and using imidacloprid and its analogues NTN32692 as a model,new compounds which contain the framework of imidacloprid linking cyclohexane were synthesized and characterized with 1H NMR,IR and HR-MS.The bioassay indicates that nine nitromethylene heterocycle compounds have certain insecticidal activities against Aphis craccivora at 500 mg/L and the best one is 73%.
Neonicotinoid-insecticides are the inhibitors of insect nAChRs with higher herbicidal activity,higher degree of selectivity,and excellent environmental safety.Based on the relationship between structure and activity of nitromethylene heterocycle compounds,and using imidacloprid and its analogues NTN32692 as a model,new compounds which contain the framework of imidacloprid linking cyclohexane were synthesized and characterized with 1H NMR,IR and HR-MS.The bioassay indicates that nine nitromethylene heterocycle compounds have certain insecticidal activities against Aphis craccivora at 500 mg/L and the best one is 73%.
2007, 24(4): 374-377
Abstract:
The first and second critical micell concentrations of the tetraethylammonium hydroxide aqueous solution obtained by conductivity method were 0.52 mmol/L and 38.0 mmol/L.Electrochemical behavior of tetraethylammonium hydroxide aqueous solution was investigated by cyclic voltammetry(CV) using a Pt working electrode and a oxidative peak under diffusion control was found.The diffusion coefficients of tetraethylammonium hydroxide was determined by potential-step chronocoulometry(CC),and the first and second critical micell concentrations obtained were 0.52 mmol/L and 41.0 mmol/L.We can conclude that the critical micell concentrations of tetraethanolammonium hydroxide aqueous solution are 0.52 mmol/L and 39.5 mmol/L.The results show that the conductivity method and chronocoulometry are all suitable for determining the critical micell concentrations of surfactants.
The first and second critical micell concentrations of the tetraethylammonium hydroxide aqueous solution obtained by conductivity method were 0.52 mmol/L and 38.0 mmol/L.Electrochemical behavior of tetraethylammonium hydroxide aqueous solution was investigated by cyclic voltammetry(CV) using a Pt working electrode and a oxidative peak under diffusion control was found.The diffusion coefficients of tetraethylammonium hydroxide was determined by potential-step chronocoulometry(CC),and the first and second critical micell concentrations obtained were 0.52 mmol/L and 41.0 mmol/L.We can conclude that the critical micell concentrations of tetraethanolammonium hydroxide aqueous solution are 0.52 mmol/L and 39.5 mmol/L.The results show that the conductivity method and chronocoulometry are all suitable for determining the critical micell concentrations of surfactants.
2007, 24(4): 378-382
Abstract:
Four ionic liquids(ILs),namely,1-alkyl-3-methylimidazolium L-lactates(alkyl includes ethyl,butyl,hexyl and octyl),were synthesized via a metathesis reaction of silver L-lactate with corresponding 1-alkyl-3-methylimidazolium bromides and characterized by 1H NMR and FT-IR spectra.The physical properties including optical rotation,solubility,density,viscosity,thermal decomposition temperature were meased and reported for the first time.The 1-alkyl-3-methylimidazolium L-lactates are highly optical active chiral ILs,possessing optical purity over 96%ee.The optical rotation of the compounds results from the chiral lactate anions.Their solubility depends on the solubility parameters of the solvents,and they are easy to dissolve in solvents with higher solubility parameter than themselves.They are stable at temperatures lower than 240℃ and behave as Newtonian fluids.Quantitative temperature-dependences of density and viscosity have been obtained.Their solubility,density and viscosity can be finely modified by changing the size of the substituent on the cation.
Four ionic liquids(ILs),namely,1-alkyl-3-methylimidazolium L-lactates(alkyl includes ethyl,butyl,hexyl and octyl),were synthesized via a metathesis reaction of silver L-lactate with corresponding 1-alkyl-3-methylimidazolium bromides and characterized by 1H NMR and FT-IR spectra.The physical properties including optical rotation,solubility,density,viscosity,thermal decomposition temperature were meased and reported for the first time.The 1-alkyl-3-methylimidazolium L-lactates are highly optical active chiral ILs,possessing optical purity over 96%ee.The optical rotation of the compounds results from the chiral lactate anions.Their solubility depends on the solubility parameters of the solvents,and they are easy to dissolve in solvents with higher solubility parameter than themselves.They are stable at temperatures lower than 240℃ and behave as Newtonian fluids.Quantitative temperature-dependences of density and viscosity have been obtained.Their solubility,density and viscosity can be finely modified by changing the size of the substituent on the cation.
2007, 24(4): 383-387
Abstract:
The photoelectrochemical behavior of nanocrystalline ZnO electrode sensitized by Cy5(a novel squarylium cyanine dye) was reported.The sensitization conditions were optimized.The ground state level and the excited state level of the dye were determined by using cyclic voltammetry and optical absorption spectroscopy.The results show that the excited state level of this dye matches the conduction band edge of ZnO nano-particles.Therefore the sensitization of the dye can obviously increase the photocurrent density of the nanocrystalline ZnO electrode and result in a red-shift of optical absorption from the ultra-violet region to the visible region.As a result,the light-to-electricity conversion efficiency was greatly improved and the maximum value of IPCE reached 36.1% and η was 0.69% when the ZnO nanostructured porous film was 2.9 μm thick and sensitized for 0.5 h.
The photoelectrochemical behavior of nanocrystalline ZnO electrode sensitized by Cy5(a novel squarylium cyanine dye) was reported.The sensitization conditions were optimized.The ground state level and the excited state level of the dye were determined by using cyclic voltammetry and optical absorption spectroscopy.The results show that the excited state level of this dye matches the conduction band edge of ZnO nano-particles.Therefore the sensitization of the dye can obviously increase the photocurrent density of the nanocrystalline ZnO electrode and result in a red-shift of optical absorption from the ultra-violet region to the visible region.As a result,the light-to-electricity conversion efficiency was greatly improved and the maximum value of IPCE reached 36.1% and η was 0.69% when the ZnO nanostructured porous film was 2.9 μm thick and sensitized for 0.5 h.
2007, 24(4): 388-391
Abstract:
Oxygen electrodes were made by means of the hot pressure method with acetylene black,active carbon,graphite and Mn(NO3)2 as row materials,and they were used in photoelectrocatalytic degradation of phenol in water.The electrodes were characterized by BET,XRD and SEM.The effects of the conditions of preparing the oxygen electrode on the degradation rate of phenol were investigated. The effects of different cathodes of Cu,Ni and oxygen electrodes on the degradation of phenol were compared.The removal of phenol in the different processes including adsorption,photocatalysis,electrocatalysis and photoelectrocatalysis were also compared under the same experimental conditions.The results show that the specific surface area of the oxygen electrode was large,and the main crystalline of this electrode was graphite and Mn3O4.The materials and pores were well-distributed on the surface and inside of the oxygen electrode.The favorite conditions of preparing oxygen cathodes are that the mass ratio of graphite:acetylene black:activated carbon is 1:1:1,the sintering temperature of the cathode is 400℃ and the thickness of the cathode is 1 mm.The oxygen electrode displays a good synergy with the photoanode in the photoelectrocatalytic degradation of phenol and enhanced the mineralization of phenol in water.
Oxygen electrodes were made by means of the hot pressure method with acetylene black,active carbon,graphite and Mn(NO3)2 as row materials,and they were used in photoelectrocatalytic degradation of phenol in water.The electrodes were characterized by BET,XRD and SEM.The effects of the conditions of preparing the oxygen electrode on the degradation rate of phenol were investigated. The effects of different cathodes of Cu,Ni and oxygen electrodes on the degradation of phenol were compared.The removal of phenol in the different processes including adsorption,photocatalysis,electrocatalysis and photoelectrocatalysis were also compared under the same experimental conditions.The results show that the specific surface area of the oxygen electrode was large,and the main crystalline of this electrode was graphite and Mn3O4.The materials and pores were well-distributed on the surface and inside of the oxygen electrode.The favorite conditions of preparing oxygen cathodes are that the mass ratio of graphite:acetylene black:activated carbon is 1:1:1,the sintering temperature of the cathode is 400℃ and the thickness of the cathode is 1 mm.The oxygen electrode displays a good synergy with the photoanode in the photoelectrocatalytic degradation of phenol and enhanced the mineralization of phenol in water.
2007, 24(4): 392-395
Abstract:
This paper reports the preparation of three alkyl imidazalium ionic liquids,1butyl-3-methylimidazolium chloride(bmimCl),1-butyl-3-methylimidazolium tetrafluoroborate(bmimBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate(bmimPF6).At 60℃ and under 2 MPa,the Wacker reaction of 1-heptene oxidized with molecular oxygen to 2-heptanone with PdCl2-CuCl2 as the catalyst was studied in different reaction media,bmimPF6,acidic aqueous solution and solvent-free.It shows that 2-heptanone is formed in all of the above three cases and the conversions can reach 90% after a reaction time of 6 h.However,the selectivity in bmimPF6 for 2-heptanone is much higher than those in acidic aqueous solution and in heptene(solvent-free).In order to study the stability of the catalyst,the experiments were repeated in acidic aqueous solution and in bmimPF6 solvent.The results show that the palladium chloride catalyst is more stable in bmimPF6.It indicates that ionic liquids can be used as an alternative for the traditional,toxic,volatile organic solvents for Wacker reaction.
This paper reports the preparation of three alkyl imidazalium ionic liquids,1butyl-3-methylimidazolium chloride(bmimCl),1-butyl-3-methylimidazolium tetrafluoroborate(bmimBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate(bmimPF6).At 60℃ and under 2 MPa,the Wacker reaction of 1-heptene oxidized with molecular oxygen to 2-heptanone with PdCl2-CuCl2 as the catalyst was studied in different reaction media,bmimPF6,acidic aqueous solution and solvent-free.It shows that 2-heptanone is formed in all of the above three cases and the conversions can reach 90% after a reaction time of 6 h.However,the selectivity in bmimPF6 for 2-heptanone is much higher than those in acidic aqueous solution and in heptene(solvent-free).In order to study the stability of the catalyst,the experiments were repeated in acidic aqueous solution and in bmimPF6 solvent.The results show that the palladium chloride catalyst is more stable in bmimPF6.It indicates that ionic liquids can be used as an alternative for the traditional,toxic,volatile organic solvents for Wacker reaction.
2007, 24(4): 396-400
Abstract:
With a series of carboxylic acids of double rings substituted by n-propyl,n-pentyl with p-hydroxyl benzaldehyde as reactants,four liquid crystal compounds of multi-ring monoesteryl aryl aldehydes were synthesized by the reactions of chloridating and esterifying at room temperature.They were 4-(4-(trans-4-propylcyclohexyl) benzoyloxy) benzaldehyde,4-(trans-4-(trans-4-propcyclohexyl)cyclohexacyloxy)benzaldehyde,4-(4-(trans-4-pentylcyclohexyl)cyclohexacyloxy)benzaldehyde,and 4-(4-(4-pentylphenyl)benzoyloxy)benzaldehyde.Their structures were identified by IR,MS,1H NMR and elemental analysis.DSC measurement showed their mesophase.POM(polarizing optical microscope) revealed their obvious nematic schlieren and streak textures.The results show that chloridating of carboxylic acid at room temperature can inhibit the configuration transforming of trans-cyclohe-xane and the temperature range of phase transition for the resulting compounds is 107~156℃.
With a series of carboxylic acids of double rings substituted by n-propyl,n-pentyl with p-hydroxyl benzaldehyde as reactants,four liquid crystal compounds of multi-ring monoesteryl aryl aldehydes were synthesized by the reactions of chloridating and esterifying at room temperature.They were 4-(4-(trans-4-propylcyclohexyl) benzoyloxy) benzaldehyde,4-(trans-4-(trans-4-propcyclohexyl)cyclohexacyloxy)benzaldehyde,4-(4-(trans-4-pentylcyclohexyl)cyclohexacyloxy)benzaldehyde,and 4-(4-(4-pentylphenyl)benzoyloxy)benzaldehyde.Their structures were identified by IR,MS,1H NMR and elemental analysis.DSC measurement showed their mesophase.POM(polarizing optical microscope) revealed their obvious nematic schlieren and streak textures.The results show that chloridating of carboxylic acid at room temperature can inhibit the configuration transforming of trans-cyclohe-xane and the temperature range of phase transition for the resulting compounds is 107~156℃.
2007, 24(4): 401-405
Abstract:
Pseudo-ternary phase diagrams of reverse microemulsion systems of cetyl trimethyl ammonium bromide(CTAB),n-butanol,n-octane and Na2WO4 solution were studied by measuring the conductivity of the system.The composition range of the reverse microemulsion system that existed stably under different conditions was investigated.WO3 nanoparticles were prepared under optimal conditions determined from the phase diagrams of the microemulsion systems.It was found that the ratio of surfactantaid to surfactant,and the concentration of Na2WO4 solution are two significant factors to affect the stability of the microemulsion system.When the ratio of m(CTAB):m(n-butanol) is 1:2 and the concentration of Na2WO4 solution is 0.05~0.08 g/mL,the microemulsion phase regions of the reverse microemulsion system that exists stably is bigger;when m(CTAB+n-butanol):m(n-octane) is 2:3,the system has the most quantity of dissolved water;and this system is insensitive to temperature.Under the optimal conditions,WO3 nanoparticles were prepared from the reaction of reverse microemulsion of Na2WO4 solution(0.08 g/mL) and hydrochloric acid reverse microemulsion at 40℃ for 7 h.The WO3 nanoparticles were characterized by TEM and the average particle size was about 30 nm.
Pseudo-ternary phase diagrams of reverse microemulsion systems of cetyl trimethyl ammonium bromide(CTAB),n-butanol,n-octane and Na2WO4 solution were studied by measuring the conductivity of the system.The composition range of the reverse microemulsion system that existed stably under different conditions was investigated.WO3 nanoparticles were prepared under optimal conditions determined from the phase diagrams of the microemulsion systems.It was found that the ratio of surfactantaid to surfactant,and the concentration of Na2WO4 solution are two significant factors to affect the stability of the microemulsion system.When the ratio of m(CTAB):m(n-butanol) is 1:2 and the concentration of Na2WO4 solution is 0.05~0.08 g/mL,the microemulsion phase regions of the reverse microemulsion system that exists stably is bigger;when m(CTAB+n-butanol):m(n-octane) is 2:3,the system has the most quantity of dissolved water;and this system is insensitive to temperature.Under the optimal conditions,WO3 nanoparticles were prepared from the reaction of reverse microemulsion of Na2WO4 solution(0.08 g/mL) and hydrochloric acid reverse microemulsion at 40℃ for 7 h.The WO3 nanoparticles were characterized by TEM and the average particle size was about 30 nm.
2007, 24(4): 406-410
Abstract:
Polymer imidazole salt 1 is a new kind of polymer phase transfer catalyst,which has the advantages of convenience for preparation,good thermal stability,and high catalytic activity.Its decomposition temperature determined by TGA is about 350℃.Some fluorinitrobenzene derivatives were prepared via halex fluorination catalyzed by polymer imidazole salt from corresponding chloronitrobenzene derivatives under the irradiation of microwave.The yield of products was in a range of 72.1%~94.4%,and the reaction time can be shortened by more than 60% in comparison with conventional heating.More aprotic solvents can be used in halogen-exchange fluorination under the irradiation of microwave.In addition,"non-thermal effect" can be shown obviously when the reaction is carried out in medium polar aprotic solvents.
Polymer imidazole salt 1 is a new kind of polymer phase transfer catalyst,which has the advantages of convenience for preparation,good thermal stability,and high catalytic activity.Its decomposition temperature determined by TGA is about 350℃.Some fluorinitrobenzene derivatives were prepared via halex fluorination catalyzed by polymer imidazole salt from corresponding chloronitrobenzene derivatives under the irradiation of microwave.The yield of products was in a range of 72.1%~94.4%,and the reaction time can be shortened by more than 60% in comparison with conventional heating.More aprotic solvents can be used in halogen-exchange fluorination under the irradiation of microwave.In addition,"non-thermal effect" can be shown obviously when the reaction is carried out in medium polar aprotic solvents.
2007, 24(4): 411-415
Abstract:
The interaction between artemisinin and DNA was studied by cyclic voltammetry and UV-Vis spectroscopy in a Britton-Robinson buffer solution(pH=7.4) containing 20% ethanol.The results would be helpful to understanding the antitumor mechanism of artemisinin and its derivatives.The electrochemical results show that the reduction peak current of artemisinin at a potential of -0.672 V at sliver electrode decreased and the peak potential shifted positively with adding DNA in artemisinin solution.The comparison of the interactions of dsDNA and ssDNA with artemisinin indicates that artemisinin reacted with DNA in a mode of intercalation to form an electrochemically inactive complex.The calculation via electrochemical method shows that the ratio of DNA:artemisinin was 1:4 and the combination constant was 3.6×104.The determination of electrochemical parameters(α,β and Ks) in the absence and the presence of DNA also shows that an electrochemically inactive complex was formed and the reaction was controlled by a diffusion-controlled electrode process.UV-Vis spectroscopic studies further confirmed the intercalation between artemisinin and DNA.The experiments of spectroscopic titration indicated that one DNA molecule combined with four artemisinin molecules and the binding constant reached 4.0×104,which was similar to the result from electrochemical method.These results show that artemisinin might combine with the DNA of nucleus which induced the apoptosis of the cells when it entered into them.
The interaction between artemisinin and DNA was studied by cyclic voltammetry and UV-Vis spectroscopy in a Britton-Robinson buffer solution(pH=7.4) containing 20% ethanol.The results would be helpful to understanding the antitumor mechanism of artemisinin and its derivatives.The electrochemical results show that the reduction peak current of artemisinin at a potential of -0.672 V at sliver electrode decreased and the peak potential shifted positively with adding DNA in artemisinin solution.The comparison of the interactions of dsDNA and ssDNA with artemisinin indicates that artemisinin reacted with DNA in a mode of intercalation to form an electrochemically inactive complex.The calculation via electrochemical method shows that the ratio of DNA:artemisinin was 1:4 and the combination constant was 3.6×104.The determination of electrochemical parameters(α,β and Ks) in the absence and the presence of DNA also shows that an electrochemically inactive complex was formed and the reaction was controlled by a diffusion-controlled electrode process.UV-Vis spectroscopic studies further confirmed the intercalation between artemisinin and DNA.The experiments of spectroscopic titration indicated that one DNA molecule combined with four artemisinin molecules and the binding constant reached 4.0×104,which was similar to the result from electrochemical method.These results show that artemisinin might combine with the DNA of nucleus which induced the apoptosis of the cells when it entered into them.
2007, 24(4): 416-419
Abstract:
The monomers maleic acid anhydride(MAH),styrene monomer(St) and initiator were dissolved in supercritical CO2,which was used as swelling agent and carrier to help these molecules impregnate into polypropylene(PP) matrix.Then impregnated molecules were grafted at 100℃ for 4 h to modify the matrix.The effects of different experimental conditions such as impregnation temperature,supercritical CO2 pressure and initiator concentration on grafting were studied.FT-IR results and SEM analysis of the grafted sample indicte that the monomers were indeed grafted onto PP chains.DSC results show that the melting point(Tm) and apparent crystallinity(Ca) decreased with the grafting rate increasing,which is due to the grafted branches that disrupt the regularity of the chain structure and increase the spaces between the chains.
The monomers maleic acid anhydride(MAH),styrene monomer(St) and initiator were dissolved in supercritical CO2,which was used as swelling agent and carrier to help these molecules impregnate into polypropylene(PP) matrix.Then impregnated molecules were grafted at 100℃ for 4 h to modify the matrix.The effects of different experimental conditions such as impregnation temperature,supercritical CO2 pressure and initiator concentration on grafting were studied.FT-IR results and SEM analysis of the grafted sample indicte that the monomers were indeed grafted onto PP chains.DSC results show that the melting point(Tm) and apparent crystallinity(Ca) decreased with the grafting rate increasing,which is due to the grafted branches that disrupt the regularity of the chain structure and increase the spaces between the chains.
2007, 24(4): 420-424
Abstract:
We show that peat can enrich nickel under static conditions by means of Liquid Scintillation Coun-ting.It was found that the adsorption of 63Ni on peat reached 69% in 5 min,and equilibrium.It was deduced from ionisation equilibrium of peat,ion exchange equilibrium between hydrogen ion and nickel ion,and mass balance among peat-water system that the adsorption amount of 63Ni depended on concentration of hydrogen ion and nickel ion in equilibrium state.The pH value showed great influence on the adsorption of nickel onto peat.Along with the increase of aqueous pH value,the transfer rate constant from water compartment to peat compartment increases gradually while the transfer rate constant from peat compartment to water compartment decreases progressively.The ratio between two of rate constants increases with pH.At pH=4.624 6,the two reversible transfer rate constants both equal 2.51.The ability of peat to bind Ni increases with the increase in pH.The adsorption kinetics of nickel on peat can be described by a closed two-compartment model.Theoretical data were in good agreement with experimental data after fitting.
We show that peat can enrich nickel under static conditions by means of Liquid Scintillation Coun-ting.It was found that the adsorption of 63Ni on peat reached 69% in 5 min,and equilibrium.It was deduced from ionisation equilibrium of peat,ion exchange equilibrium between hydrogen ion and nickel ion,and mass balance among peat-water system that the adsorption amount of 63Ni depended on concentration of hydrogen ion and nickel ion in equilibrium state.The pH value showed great influence on the adsorption of nickel onto peat.Along with the increase of aqueous pH value,the transfer rate constant from water compartment to peat compartment increases gradually while the transfer rate constant from peat compartment to water compartment decreases progressively.The ratio between two of rate constants increases with pH.At pH=4.624 6,the two reversible transfer rate constants both equal 2.51.The ability of peat to bind Ni increases with the increase in pH.The adsorption kinetics of nickel on peat can be described by a closed two-compartment model.Theoretical data were in good agreement with experimental data after fitting.
2007, 24(4): 425-428
Abstract:
LiV3O8 as cathode material for lithium batteries was prepared via sol-gel method.Effects of the concentration of LiOH solution on the particle size,the structure,the electrical conductivity and the electrochemical performance of LiV3O8 were studied.It was found that the intensity of X-ray diffraction peaks,the particle size and the electrical conductivity of LiV3O8 can be controlled by changing the concentration of the LiOH solution.The paticle size distribution and the structure of LiV3O8 and the electrochemical perfor-mance were measured.The results show that the crystallization degree and the intensity of peak(100) decreased with the increase of the LiOH concentration.An ideal particle size distribution and a high electrical conductivity value(9.06×10-2 s/cm) was obtained at a concentration of 0.030 mol/L.The capacity and the cycle performance of LiV3O8 were found to depend on the concentration of the LiOH solution.The specific capacity was 310 mA·h/g and the cycle performance decreased by 4% after 15 cycles at a LiOH concentration of 0.030 mol/L.
LiV3O8 as cathode material for lithium batteries was prepared via sol-gel method.Effects of the concentration of LiOH solution on the particle size,the structure,the electrical conductivity and the electrochemical performance of LiV3O8 were studied.It was found that the intensity of X-ray diffraction peaks,the particle size and the electrical conductivity of LiV3O8 can be controlled by changing the concentration of the LiOH solution.The paticle size distribution and the structure of LiV3O8 and the electrochemical perfor-mance were measured.The results show that the crystallization degree and the intensity of peak(100) decreased with the increase of the LiOH concentration.An ideal particle size distribution and a high electrical conductivity value(9.06×10-2 s/cm) was obtained at a concentration of 0.030 mol/L.The capacity and the cycle performance of LiV3O8 were found to depend on the concentration of the LiOH solution.The specific capacity was 310 mA·h/g and the cycle performance decreased by 4% after 15 cycles at a LiOH concentration of 0.030 mol/L.
2007, 24(4): 429-433
Abstract:
The scale inhibition performance of different antiscalants,PESA,PASP,DEPTMP and SHMP were determined by measuring the maximum relative degree of supersaturation of BaSO4 under the same antiscalant concentration via a method based on conductivity titration.The result indicates the sequence of scale inhibition performances is PESA> PASP> DEPTMP> SHMP,which is the same as that obtained by static method.Comparison between the two methods demonstrates that the conductivity titration method is more reliable.In addition,it shows that the conductivity titration method is a fast,easy,convenient,good repeatable technique,which can also be used to evaluate the synergistic inhibiting effect of antiscalants on preventing BaSO4 precipitation.
The scale inhibition performance of different antiscalants,PESA,PASP,DEPTMP and SHMP were determined by measuring the maximum relative degree of supersaturation of BaSO4 under the same antiscalant concentration via a method based on conductivity titration.The result indicates the sequence of scale inhibition performances is PESA> PASP> DEPTMP> SHMP,which is the same as that obtained by static method.Comparison between the two methods demonstrates that the conductivity titration method is more reliable.In addition,it shows that the conductivity titration method is a fast,easy,convenient,good repeatable technique,which can also be used to evaluate the synergistic inhibiting effect of antiscalants on preventing BaSO4 precipitation.
2007, 24(4): 434-438
Abstract:
Ammonium polyphosphate(APP) which was surface-modified with melamine(MA) and 2,4-toluene diisocyanate(TDI) in turn was used as flame-retardant in linear low density polyethylene(LLDPE).Its water resistance was evaluated with its water-solubility and the changes of LOI and P content of the LLDPE after being immersed in water.The water-solubility of the surface-modified APP was reduced from 0.368 0 for unmodified-APP to 0.212 3 for MA-TDI-APP.The LOI and P content changes of the LLDPE treated with surface-modified APP were reduced after being immersed in water.When APP addition was 30%,the LOI change of the LLDPE was reduced 2.5% MA-TDI-APP and 5.3% with respect to unmodified-APP.The P copntent change of the LLDPE was more than 6.5% for unmodified-APP and under 4% for MA-TDI-APP.The compatibility of modified-APP was observed with SEM and the surface-modified APP had a better compatibility with LLDPE.
Ammonium polyphosphate(APP) which was surface-modified with melamine(MA) and 2,4-toluene diisocyanate(TDI) in turn was used as flame-retardant in linear low density polyethylene(LLDPE).Its water resistance was evaluated with its water-solubility and the changes of LOI and P content of the LLDPE after being immersed in water.The water-solubility of the surface-modified APP was reduced from 0.368 0 for unmodified-APP to 0.212 3 for MA-TDI-APP.The LOI and P content changes of the LLDPE treated with surface-modified APP were reduced after being immersed in water.When APP addition was 30%,the LOI change of the LLDPE was reduced 2.5% MA-TDI-APP and 5.3% with respect to unmodified-APP.The P copntent change of the LLDPE was more than 6.5% for unmodified-APP and under 4% for MA-TDI-APP.The compatibility of modified-APP was observed with SEM and the surface-modified APP had a better compatibility with LLDPE.
2007, 24(4): 439-442
Abstract:
The mixed valence oxide WO2.50 assembled flake was synthesized through internal redox method.Transmission electron microscope(TEM) observations indicated that the product was 0.7~1.2 μm long and 180~250 nm wide,which was assembled from nanoparticles with a diameter of about 45 nm.The product contained two phases,WO2.00 and WO2.90,and had a good crystallinity,and its specific surface area was 13.6 m2/g.The product had good conductivity(the resistivity was 0.1 Ω·cm) and affinity for resin.The absorption peak of the product in the FT-IR spectrum had a "red shift" of 33 cm-1.The thermochemistry of the precursor has been studied by TG-DSC,and the best reaction temperature was found to be 750℃.The formation mechanism of the WO2.50 assembly flake was proposed.The WO2.50 asembled flake was applied in conductive coating field for the first time and the resistivity of the coating film was 5 Ω·m.
The mixed valence oxide WO2.50 assembled flake was synthesized through internal redox method.Transmission electron microscope(TEM) observations indicated that the product was 0.7~1.2 μm long and 180~250 nm wide,which was assembled from nanoparticles with a diameter of about 45 nm.The product contained two phases,WO2.00 and WO2.90,and had a good crystallinity,and its specific surface area was 13.6 m2/g.The product had good conductivity(the resistivity was 0.1 Ω·cm) and affinity for resin.The absorption peak of the product in the FT-IR spectrum had a "red shift" of 33 cm-1.The thermochemistry of the precursor has been studied by TG-DSC,and the best reaction temperature was found to be 750℃.The formation mechanism of the WO2.50 assembly flake was proposed.The WO2.50 asembled flake was applied in conductive coating field for the first time and the resistivity of the coating film was 5 Ω·m.
2007, 24(4): 443-447
Abstract:
Polyphenols were obtained from green tea by soaking it with ethanol,followed by concentration,decolorization and extraction with ethyl acetate.High purity(-)-EGCG was then obtained by polyamide packed chromatographic column separation.Orthogonal design of experiment was used to determine the optimal amount of alcohol,extraction times and particle diameter of green tea to maximize the extraction yield of(-)-EGCG.The optimal conditions were determined as follows.Twelve mL of 95% alcohol were used to extract 1 g of green tea with particle size less than 0.960 mm for 1 hour and the extraction was repeated 3 times.The decolorization of the ethanol extract of green tea with active carbon was studied.Optimal results of decolorization were obtained by using 0.36 g of activated carbon to decolor 1 g of green tea for 30 min and the decolorization was repeated 2 times.The polyamide chromatography separation conditions of crude polyphenol were investigated.The influence of particle size and amount of polyamide used on extraction yield of(-)-EGCG were studied.It was found that best separation results were obtained if 50 g of polyamide with particle size of 0.170~0.210 mm were used for 1 g extraction of green tea.0.04 g of(-)-EGCG with over 99.0% purity was obtained from 1 g of green tea through optimized process of ethanol extraction,discolo-rization and separation.The extraction yield of(-)-EGCG was 50%.The structure of the final product separated was identified by LC-MS,elemental analysis,UV,IR,HPLC and NMR.It was experimentally demonstrated that the proposed process is a safe,mild,low cost and waste free procedure.
Polyphenols were obtained from green tea by soaking it with ethanol,followed by concentration,decolorization and extraction with ethyl acetate.High purity(-)-EGCG was then obtained by polyamide packed chromatographic column separation.Orthogonal design of experiment was used to determine the optimal amount of alcohol,extraction times and particle diameter of green tea to maximize the extraction yield of(-)-EGCG.The optimal conditions were determined as follows.Twelve mL of 95% alcohol were used to extract 1 g of green tea with particle size less than 0.960 mm for 1 hour and the extraction was repeated 3 times.The decolorization of the ethanol extract of green tea with active carbon was studied.Optimal results of decolorization were obtained by using 0.36 g of activated carbon to decolor 1 g of green tea for 30 min and the decolorization was repeated 2 times.The polyamide chromatography separation conditions of crude polyphenol were investigated.The influence of particle size and amount of polyamide used on extraction yield of(-)-EGCG were studied.It was found that best separation results were obtained if 50 g of polyamide with particle size of 0.170~0.210 mm were used for 1 g extraction of green tea.0.04 g of(-)-EGCG with over 99.0% purity was obtained from 1 g of green tea through optimized process of ethanol extraction,discolo-rization and separation.The extraction yield of(-)-EGCG was 50%.The structure of the final product separated was identified by LC-MS,elemental analysis,UV,IR,HPLC and NMR.It was experimentally demonstrated that the proposed process is a safe,mild,low cost and waste free procedure.
2007, 24(4): 448-451
Abstract:
Five tricyclic diterpenes(compounds 2,3,4,5 and 6) were synthesized from(±)-13-methoxy-8,11,13-podocarpatriene(1) via a simple approach,in which the ethyl group of compound 2 was introduced via alkyl substitution reaction when compound 1 was treated with n-BuLi and then reacted with ethyl bromide at -78℃.The oxidation of compound 2 with CrO3 afforded compound 3 at -78℃.Compound 1 was treated with n-BuLi,alkylated with i-propyl bromide and then oxidized by CrO3-HOAc to afford ketone 4.Diketone 5 was obtained by farther oxidation of ketone 4 using Jones reagent.Compound 6 was obtained by the enolization of compound 5 with the mixture of t-BuOK and t-BuOH.1H NMR,13C NMR,IR,MS(EI),HRMS and element analysis were used to confirm the structures of compounds 2~6,and the results are consistent with those in literature.In conclusion,the target compounds were successfully synthesized with the method in this paper.
Five tricyclic diterpenes(compounds 2,3,4,5 and 6) were synthesized from(±)-13-methoxy-8,11,13-podocarpatriene(1) via a simple approach,in which the ethyl group of compound 2 was introduced via alkyl substitution reaction when compound 1 was treated with n-BuLi and then reacted with ethyl bromide at -78℃.The oxidation of compound 2 with CrO3 afforded compound 3 at -78℃.Compound 1 was treated with n-BuLi,alkylated with i-propyl bromide and then oxidized by CrO3-HOAc to afford ketone 4.Diketone 5 was obtained by farther oxidation of ketone 4 using Jones reagent.Compound 6 was obtained by the enolization of compound 5 with the mixture of t-BuOK and t-BuOH.1H NMR,13C NMR,IR,MS(EI),HRMS and element analysis were used to confirm the structures of compounds 2~6,and the results are consistent with those in literature.In conclusion,the target compounds were successfully synthesized with the method in this paper.
2007, 24(4): 452-456
Abstract:
The adsorption and thermodynamic behavior of threonine and glutamic acid in aqueous solution on D318 resin selected from eight different structural anion exchange resins were investigated by the static method.Two models of Langmuir and Freundlich were used to simulate the equilibrium adsorption isotherm curves of threonine and glutamic acid.The results show that the adsorption isotherm curves of threonine and glutamic acid on D318 resin fit in better with Langmuir adsorption isotherm equation and the adsorption of them on D318 resin behave benefitful adsorption.The study of thermodynamics show that when the adsorption of threonine are 8~10 mg/g in 293~313 K,adsorption enthalpy change ΔH are 30.026~31.615 kJ/mol,free energys ΔG-14.337~-26.340 kJ/mol,entropys of adsorption ΔS-48.616~-16.855 J/(mol·K);and when the adsorption of glutamic acid are 30~50 mg/g in 293~313 K,adsorption enthalpy ΔH are-58.036~-60.053 kJ/mol,free energys ΔG-85.017~-137.647 kJ/mol,entropys of adsorption ΔS 92.084~247.905 J/(mol·K).
The adsorption and thermodynamic behavior of threonine and glutamic acid in aqueous solution on D318 resin selected from eight different structural anion exchange resins were investigated by the static method.Two models of Langmuir and Freundlich were used to simulate the equilibrium adsorption isotherm curves of threonine and glutamic acid.The results show that the adsorption isotherm curves of threonine and glutamic acid on D318 resin fit in better with Langmuir adsorption isotherm equation and the adsorption of them on D318 resin behave benefitful adsorption.The study of thermodynamics show that when the adsorption of threonine are 8~10 mg/g in 293~313 K,adsorption enthalpy change ΔH are 30.026~31.615 kJ/mol,free energys ΔG-14.337~-26.340 kJ/mol,entropys of adsorption ΔS-48.616~-16.855 J/(mol·K);and when the adsorption of glutamic acid are 30~50 mg/g in 293~313 K,adsorption enthalpy ΔH are-58.036~-60.053 kJ/mol,free energys ΔG-85.017~-137.647 kJ/mol,entropys of adsorption ΔS 92.084~247.905 J/(mol·K).
2007, 24(4): 457-460
Abstract:
This paper reports the influences of extraction time,the ratio of solid-liquid,solvent pH and experiment temperature of caffeine extraction yield from tea.Orthogonal experiment was implemented based on single factor experiment.The optimum extraction parameters are 80℃,90 minutes,a liquid-feed ratio of 30:1 and pH=7.Experimental data were subjected to multivariate first-order regression and multivariate quadratic regression,and two regressing equations were obtained.At last,a neural network model based on the orthogonal experiment data was established to obtain the optimum extraction parameters, namely,100℃,115 minutes,a liquid-feed ratio of 41:1 and pH=4.5,and the experimental result based on the parameters from the artificial neural network is better than that based on orthogonal experiment.
This paper reports the influences of extraction time,the ratio of solid-liquid,solvent pH and experiment temperature of caffeine extraction yield from tea.Orthogonal experiment was implemented based on single factor experiment.The optimum extraction parameters are 80℃,90 minutes,a liquid-feed ratio of 30:1 and pH=7.Experimental data were subjected to multivariate first-order regression and multivariate quadratic regression,and two regressing equations were obtained.At last,a neural network model based on the orthogonal experiment data was established to obtain the optimum extraction parameters, namely,100℃,115 minutes,a liquid-feed ratio of 41:1 and pH=4.5,and the experimental result based on the parameters from the artificial neural network is better than that based on orthogonal experiment.
2007, 24(4): 461-464
Abstract:
N-(6-methyl-2-pyridine)-amino-methylene-diethyl malonate was produced by condensation reaction of 2-amino-6-methyl pyridine with ethoxymethylene diethyl malonate under optimal conditions that n(2-amino-6-methyl pyridine):n(ethoxymethylene diethyl malonate) is 1:1.3, reacting time 45 min and temperature 130℃,the yield of this reaction was 96%,which was 6% higher than that of literature.Then 4-oxy-7-methyl-1,8-naphththyridine-3-carboxylic acetate was synthesized by cyclization reaction in different heat carrier of diphenyl ether,paraffin oil and diethyl phthaltate in 250℃.The yields were 88.6%,56.3% and 61.2% respectively.The results show that diphenyl ether is the best heat carrier and reacting temperature has significant influence on production yield,while the ratio of raw materials and reacting time almost has no influence.Finally,1-ethyl-4-oxy-7-methyl-1,8-naphththyridine-3-carboxylic acid was produced by ethylation reaction using iodoethane,triethyl phosphate and diethyl carbonate and hydrolysis in alkaline condition.The yield of product is 92.6%,90.7% and 81.2% respectively.The influencing factors of synthetic reaction were studied and the advantages and disadvantages of using diethyl carbonate as the ethylization reagent were compared.The compounds were characterized with various spectroscopic methods.
N-(6-methyl-2-pyridine)-amino-methylene-diethyl malonate was produced by condensation reaction of 2-amino-6-methyl pyridine with ethoxymethylene diethyl malonate under optimal conditions that n(2-amino-6-methyl pyridine):n(ethoxymethylene diethyl malonate) is 1:1.3, reacting time 45 min and temperature 130℃,the yield of this reaction was 96%,which was 6% higher than that of literature.Then 4-oxy-7-methyl-1,8-naphththyridine-3-carboxylic acetate was synthesized by cyclization reaction in different heat carrier of diphenyl ether,paraffin oil and diethyl phthaltate in 250℃.The yields were 88.6%,56.3% and 61.2% respectively.The results show that diphenyl ether is the best heat carrier and reacting temperature has significant influence on production yield,while the ratio of raw materials and reacting time almost has no influence.Finally,1-ethyl-4-oxy-7-methyl-1,8-naphththyridine-3-carboxylic acid was produced by ethylation reaction using iodoethane,triethyl phosphate and diethyl carbonate and hydrolysis in alkaline condition.The yield of product is 92.6%,90.7% and 81.2% respectively.The influencing factors of synthetic reaction were studied and the advantages and disadvantages of using diethyl carbonate as the ethylization reagent were compared.The compounds were characterized with various spectroscopic methods.
2007, 24(4): 465-467
Abstract:
Synthesis of a series of N,N'-diaryl adipyl dihydrazide compounds from self-made adipic chloride and substituted phenylhydrazine were reported.Nine kinds of compounds was synthesized using the method of ice bathing.The products were confirmed by means of elemental analysis,IR and 1H NMR.Two N-H absorptions of products were observed at approximately 3 200~3 400 cm-1 in the infrared spectrum.Resonances corresponding to the N-H chemical shift were from 7.3 to 10.5 in 1H NMR.The results of elemental analysis for the products were in agreement with the theoretical values.The yields were about from 81% to 93%.
Synthesis of a series of N,N'-diaryl adipyl dihydrazide compounds from self-made adipic chloride and substituted phenylhydrazine were reported.Nine kinds of compounds was synthesized using the method of ice bathing.The products were confirmed by means of elemental analysis,IR and 1H NMR.Two N-H absorptions of products were observed at approximately 3 200~3 400 cm-1 in the infrared spectrum.Resonances corresponding to the N-H chemical shift were from 7.3 to 10.5 in 1H NMR.The results of elemental analysis for the products were in agreement with the theoretical values.The yields were about from 81% to 93%.
2007, 24(4): 468-470
Abstract:
Co:YIG and Ni:YIG powder samples were prepared by decomposing the precursors at 900℃,which were obtained by coprecipitation with precipitator NH4HCO3.Analysis results of TG-DTA show that the R:YIG phase was obtained at about 778℃.The phase structure of the powder was characterized with X-ray diffraction.The pure phase Y3Fe5-xRxO12 samples were obtained when x≤0.15.Y3Fe5-xRxO12 was a cubic lattice structure with Ia3d space group.The structure was transformed into tetragonal lattice structure when x=0.25.The impurity appeared when x>0.15.The saturated magnetization measured by VSM was enhanced with increasing doped-content x.However,the impurity phase would led to a decrease of saturated magnetization when the doped-content was too high.
Co:YIG and Ni:YIG powder samples were prepared by decomposing the precursors at 900℃,which were obtained by coprecipitation with precipitator NH4HCO3.Analysis results of TG-DTA show that the R:YIG phase was obtained at about 778℃.The phase structure of the powder was characterized with X-ray diffraction.The pure phase Y3Fe5-xRxO12 samples were obtained when x≤0.15.Y3Fe5-xRxO12 was a cubic lattice structure with Ia3d space group.The structure was transformed into tetragonal lattice structure when x=0.25.The impurity appeared when x>0.15.The saturated magnetization measured by VSM was enhanced with increasing doped-content x.However,the impurity phase would led to a decrease of saturated magnetization when the doped-content was too high.
2007, 24(4): 471-473
Abstract:
2,4-Diacetylphloroglucinol(DAPG) was synthesized via the Friedel-Crafts reaction of phloro-glucinol and acetic anhydride with BF3 as the catalyst and ether as the solvent.The product was purified by silicon gel column chromatography.The structure of DAPG was characterized by 1H NMR and MS.The reaction conditions,such as the ratio of reactants,reaction temperature and reaction time were investigated.The optimal reaction conditions were the molar ratio of phloroglucinol:acetic anhydride:BF3 being 1:2.1:5.5,reaction temperature 26~30℃ and reaction time 24 h,and the yield was 62.0%.
2,4-Diacetylphloroglucinol(DAPG) was synthesized via the Friedel-Crafts reaction of phloro-glucinol and acetic anhydride with BF3 as the catalyst and ether as the solvent.The product was purified by silicon gel column chromatography.The structure of DAPG was characterized by 1H NMR and MS.The reaction conditions,such as the ratio of reactants,reaction temperature and reaction time were investigated.The optimal reaction conditions were the molar ratio of phloroglucinol:acetic anhydride:BF3 being 1:2.1:5.5,reaction temperature 26~30℃ and reaction time 24 h,and the yield was 62.0%.
2007, 24(4): 474-476
Abstract:
The N-alkylation of N-monosubstituted sulfonamides with alkyl halides promoted by KF using ionic liquids as reaction media was reported in this paper. Four different ionic liquids,[Bmim]BF4,[Bpy]BF4 and [Bpy]PF6 were investigated,and [Bmim]PF6 showed the best effect when used as the reaction media,giving the highest yield in the shortest reaction time.Promoted by KF in [Bmim]PF6,N-aryl or N-alkyl monosubstituted sulfonamides could react with various activated halides and unactivated primary halides smoothly.Reactions were performed at 85℃ for 2~10 hours,and thirteen N-alkylation products were obtained with 70%~97% yields.Moreover,the ionic liquid recovered could be reused for three times with no appreciable decrease in yield and reaction rate.As demonstrated in this paper,both KF,which was used as mild base,and the ionic liquid [Bmim]PF6 promoted the alkylation reaction efficiently.
The N-alkylation of N-monosubstituted sulfonamides with alkyl halides promoted by KF using ionic liquids as reaction media was reported in this paper. Four different ionic liquids,[Bmim]BF4,[Bpy]BF4 and [Bpy]PF6 were investigated,and [Bmim]PF6 showed the best effect when used as the reaction media,giving the highest yield in the shortest reaction time.Promoted by KF in [Bmim]PF6,N-aryl or N-alkyl monosubstituted sulfonamides could react with various activated halides and unactivated primary halides smoothly.Reactions were performed at 85℃ for 2~10 hours,and thirteen N-alkylation products were obtained with 70%~97% yields.Moreover,the ionic liquid recovered could be reused for three times with no appreciable decrease in yield and reaction rate.As demonstrated in this paper,both KF,which was used as mild base,and the ionic liquid [Bmim]PF6 promoted the alkylation reaction efficiently.
2007, 24(4): 477-479
Abstract:
2,4-Dichlorophenoxyacetic is a kind of traditional plant growth regulator.In order to develop new kinds of plant growth regulator,we designed and synthesized 4 kinds of target compounds,N-[2-(2,4-dichlorophenoxy)acetamido](thio)urea derivatives(1~4),through esterification of 2,4-dichlorophenoxyacetic,p-phenylhydrazine acylation and nucleophilic addition of phenyl isothiocyanate.The target compounds were characterized by 1H NMR.The effect of the samples on the growth of cucumber and Mung bean were investigated at concentrations of 10,1&×10-1,1×10-2,1×10-3,1×10-4,and 0 mg/L in contrast with α-NAA.The result showed that the target compounds had good bioactivity.The samples could promote the growth of cucumber and Mung bean significantly at concentration of 1&×10-1~1×10-4 mg/L,and inhibit the growth at 10 mg/L.The effect of the samples were better than that of α-NAA.
2,4-Dichlorophenoxyacetic is a kind of traditional plant growth regulator.In order to develop new kinds of plant growth regulator,we designed and synthesized 4 kinds of target compounds,N-[2-(2,4-dichlorophenoxy)acetamido](thio)urea derivatives(1~4),through esterification of 2,4-dichlorophenoxyacetic,p-phenylhydrazine acylation and nucleophilic addition of phenyl isothiocyanate.The target compounds were characterized by 1H NMR.The effect of the samples on the growth of cucumber and Mung bean were investigated at concentrations of 10,1&×10-1,1×10-2,1×10-3,1×10-4,and 0 mg/L in contrast with α-NAA.The result showed that the target compounds had good bioactivity.The samples could promote the growth of cucumber and Mung bean significantly at concentration of 1&×10-1~1×10-4 mg/L,and inhibit the growth at 10 mg/L.The effect of the samples were better than that of α-NAA.
2007, 24(4): 480-482
Abstract:
The blends of polylactide(PLA) and poly(propylene carbonate)(PPC) were prepared by melting blend.DSC results showed the glass transition temperature(Tg) of pure PLA and PPC were 54℃ and 37℃ respectively.Different compositions of PLA/PPC blend had two distinct Tg,which were corresponding to pure PLA and PPC,suggesting that PLA and PPC blend are immiscible.Mechanical test results showed when the content of PPC was up to 20%,the yielding point,necking and strain-whitening could be observed during tensile process.With the increasing of PPC content,fracture of blends had a transition from brittle nature to tough nature.Furthermore,with the increasing of PPC content,the modulus of blends decreased,and the elongation increased.When the composition of PPC reached 50%,the elongation of blend had a maximum value 62%.The complex viscosity of the blends can be controlled in a wide range.
The blends of polylactide(PLA) and poly(propylene carbonate)(PPC) were prepared by melting blend.DSC results showed the glass transition temperature(Tg) of pure PLA and PPC were 54℃ and 37℃ respectively.Different compositions of PLA/PPC blend had two distinct Tg,which were corresponding to pure PLA and PPC,suggesting that PLA and PPC blend are immiscible.Mechanical test results showed when the content of PPC was up to 20%,the yielding point,necking and strain-whitening could be observed during tensile process.With the increasing of PPC content,fracture of blends had a transition from brittle nature to tough nature.Furthermore,with the increasing of PPC content,the modulus of blends decreased,and the elongation increased.When the composition of PPC reached 50%,the elongation of blend had a maximum value 62%.The complex viscosity of the blends can be controlled in a wide range.
2007, 24(4): 483-485
Abstract:
The water-soluble nickel nanoparticle catalyst was prepared with KBH4 as reducer and cetyl trimethyl ammonium bromide as stabilizer in aqueous solution.As is shown in the TEM and XRD results,the particle size of the catalyst is 4~6 nm and it has an amorphous structure.The catalyst was applied to the hydrogenation of o-chloronitrobenzene under very mild reaction conditions and the amount of the catalyst used in the reaction was small.The activity of the catalyst is higher than those of Raney Ni and Ni-B amorphous powder.At room temperature(25℃) and under 3.0 MPa of hydrogen,after 15 min reaction,o-CNB was all converted with a selectivity of o-CAN of 97.2%.The present catalysis system used water as solvent,and the products were easy to be obtained by simple phase separation.The results of the catalytic hydrogenation of different chloronitrobenzenes show that the catalyst exhibits a high activity and a high selectivity.For different chloronitrobenzenes,when the conversions of the substrates are higher than 99.5%,the corresponding selectivities of different chloroanilines are higher than 97.2%,which suggests that the catalyst has a wide application range.
The water-soluble nickel nanoparticle catalyst was prepared with KBH4 as reducer and cetyl trimethyl ammonium bromide as stabilizer in aqueous solution.As is shown in the TEM and XRD results,the particle size of the catalyst is 4~6 nm and it has an amorphous structure.The catalyst was applied to the hydrogenation of o-chloronitrobenzene under very mild reaction conditions and the amount of the catalyst used in the reaction was small.The activity of the catalyst is higher than those of Raney Ni and Ni-B amorphous powder.At room temperature(25℃) and under 3.0 MPa of hydrogen,after 15 min reaction,o-CNB was all converted with a selectivity of o-CAN of 97.2%.The present catalysis system used water as solvent,and the products were easy to be obtained by simple phase separation.The results of the catalytic hydrogenation of different chloronitrobenzenes show that the catalyst exhibits a high activity and a high selectivity.For different chloronitrobenzenes,when the conversions of the substrates are higher than 99.5%,the corresponding selectivities of different chloroanilines are higher than 97.2%,which suggests that the catalyst has a wide application range.
2007, 24(4): 486-488
Abstract:
Five electroreductive reactions and one electrooxidative reaction were chosen to investigate the current efficiency and the percent conversion in the presence and in absence of additives by electrolysis.The result shows that the six reactions can be divided into two groups.The first group are the reactions whose reactants are molecules in electrolyte,and the second group are the reactions whose reactants are ions in electrolyte.For the former,the current efficiencies of the reduction of m-dinitrobenzene,the oxidation of 3-methylpyridine and the reduction of o-nitrophenol in sulfuric acid changed from 65.69%,28.00% and 45.09% to 66%,28.45% and 37.07% respectively by adding additive,which indicates that the additives have little or negative effect on the reactions whose reactants are molecules in electrolyte.For the latter,the current efficiencies of the reduction of o-nitrophenol in sodium hydroxide,the synthesis of succinic acid and the reduction of salicylic acid increased to 75.80%,78.60% and 30.06% from 49.37%,65.05% and 24.55% respectively by adding additive,which means that the additive will increase the current efficiency of the reaction whose reactants are ions in electrolyte.
Five electroreductive reactions and one electrooxidative reaction were chosen to investigate the current efficiency and the percent conversion in the presence and in absence of additives by electrolysis.The result shows that the six reactions can be divided into two groups.The first group are the reactions whose reactants are molecules in electrolyte,and the second group are the reactions whose reactants are ions in electrolyte.For the former,the current efficiencies of the reduction of m-dinitrobenzene,the oxidation of 3-methylpyridine and the reduction of o-nitrophenol in sulfuric acid changed from 65.69%,28.00% and 45.09% to 66%,28.45% and 37.07% respectively by adding additive,which indicates that the additives have little or negative effect on the reactions whose reactants are molecules in electrolyte.For the latter,the current efficiencies of the reduction of o-nitrophenol in sodium hydroxide,the synthesis of succinic acid and the reduction of salicylic acid increased to 75.80%,78.60% and 30.06% from 49.37%,65.05% and 24.55% respectively by adding additive,which means that the additive will increase the current efficiency of the reaction whose reactants are ions in electrolyte.
