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2010 Volume 27 Issue 7
2010, 27(7): 745-753
doi: 10.3724/SP.J.1095.2010.90566
Abstract:
Janus particles (JPs) are a novel type of colloid particles possessing different chemical characteristics at two hemispheres of particles. The size of JPs is usually in the micro-or nano-scale. Amphiphilic JPs have received extensive attention as novel surfactants due to the hydrophobic and hydrophilic feature shown on the two hemispheres of JPs. This paper reviews the research progress in recent years on the preparation,theory,characterization of surface activities,and the application of the amphiphilic JPs. The research interests in future are discussed.
Janus particles (JPs) are a novel type of colloid particles possessing different chemical characteristics at two hemispheres of particles. The size of JPs is usually in the micro-or nano-scale. Amphiphilic JPs have received extensive attention as novel surfactants due to the hydrophobic and hydrophilic feature shown on the two hemispheres of JPs. This paper reviews the research progress in recent years on the preparation,theory,characterization of surface activities,and the application of the amphiphilic JPs. The research interests in future are discussed.
2010, 27(7): 754-758
doi: 10.3724/SP.J.1095.2010.90720
Abstract:
Multi-arm polylactide (MA-PLA) was melt-blended with commercial polylactide (PLLA) to improve its crystallinity. MA-PLA was prepared by the ring-opening polymerization of L-lactide using multihydroxy-terminated polyester as initiator. The DSC curve during the 2nd heating shows an apparent cold crystallization peak(41.5 J/g) and a melting peak(42.5 J/g) for MA-PLA,which could not be observed for commercial PLLA 3051D and indicated a better crystallinity of MA-PLA than that of 3051D. The L-lactic acid unit content in MA-PLA was 97% and was higher than that in 3051D (91%). After blending with 6% MA-PLA,the blend showed an obvious cold crystallization peak and a melting peak. Polarized optical microscopy(POM) observation revealed a faster nucleation rate and an early-stage spherulite growth rate in the blend than those in neat 3051D. The isothermal crystallization gave a half crystallization time of 53.6 min for neat 3051D and 31.7 min for the blend. In addition,the Avrami indexes(n) are 2.25 and 2.60 for 3051D and the blend,respectively. The improvement in crystallinity was ascribed to the heterophase nucleation effect caused by the multi-arm polylactide.
Multi-arm polylactide (MA-PLA) was melt-blended with commercial polylactide (PLLA) to improve its crystallinity. MA-PLA was prepared by the ring-opening polymerization of L-lactide using multihydroxy-terminated polyester as initiator. The DSC curve during the 2nd heating shows an apparent cold crystallization peak(41.5 J/g) and a melting peak(42.5 J/g) for MA-PLA,which could not be observed for commercial PLLA 3051D and indicated a better crystallinity of MA-PLA than that of 3051D. The L-lactic acid unit content in MA-PLA was 97% and was higher than that in 3051D (91%). After blending with 6% MA-PLA,the blend showed an obvious cold crystallization peak and a melting peak. Polarized optical microscopy(POM) observation revealed a faster nucleation rate and an early-stage spherulite growth rate in the blend than those in neat 3051D. The isothermal crystallization gave a half crystallization time of 53.6 min for neat 3051D and 31.7 min for the blend. In addition,the Avrami indexes(n) are 2.25 and 2.60 for 3051D and the blend,respectively. The improvement in crystallinity was ascribed to the heterophase nucleation effect caused by the multi-arm polylactide.
2010, 27(7): 759-763
doi: 10.3724/SP.J.1095.2010.90705
Abstract:
Starch foams were prepared with a twin-screw extruder from normal corn starch as raw material and water as blowing agent. The effects of blowing agent content and blend of poly(vinyl ethanol) on the structure and properties of the extruded foams were studied. The structure and mechanical properties of starch foams were characterized by means of a scanning electron microscope and a universal material testing machine respectively. The results indicate that the starch foams extruded with 8% (mass fraction) water reached the greatest radial expansion ratio and volume expansion ratio,which were 22 and 17.6 respectively,and the greatest compressive modulus(4.07 MPa). The extruded starch foams blended with 10% (mass fraction) PVA reached greater cell size(1.29 mm),cell thickness(82.43 μm),and compressive modulus(9.70 MPa).
Starch foams were prepared with a twin-screw extruder from normal corn starch as raw material and water as blowing agent. The effects of blowing agent content and blend of poly(vinyl ethanol) on the structure and properties of the extruded foams were studied. The structure and mechanical properties of starch foams were characterized by means of a scanning electron microscope and a universal material testing machine respectively. The results indicate that the starch foams extruded with 8% (mass fraction) water reached the greatest radial expansion ratio and volume expansion ratio,which were 22 and 17.6 respectively,and the greatest compressive modulus(4.07 MPa). The extruded starch foams blended with 10% (mass fraction) PVA reached greater cell size(1.29 mm),cell thickness(82.43 μm),and compressive modulus(9.70 MPa).
2010, 27(7): 764-768
doi: 10.3724/SP.J.1095.2010.90672
Abstract:
Based on the condensation reaction of glycerol with benzaldehyde,the effects of acid catalysts (p-toluenesulfonic acid(PTSA), phosphotungstic acid(PWA), KHSO4 and FeCl3,respectively) on the yield of the condensation products and the mass ratio of 5-hydroxyl-2-phenyl-1,3-dioxane(1) to 4-hydroxymethyl-2-phenyl-1,3-dioxolane (2) were investigated. Comparison tests indicated that under the conditions of cyclohexane as water entrainer and n(benzalhydehyde):n(glycerol)=2:3,KHSO4 gave the best yield (96.8%) of condensation products(compound 1+2) and PTSA yielded the highest proportion (m(1):m(2)=48.6:51.4) of compound 1 in condensation products(compound 1+2). At room temperature, PTSA, PWA, KHSO4 and FeCl3 all can,but at -20℃,only PTSA can catalyze the transformation of compound 2 to compound 1. Cis-5-hydroxyl-2-phenyl-1,3-dioxane (1a) was isolated by the catalytic transformation of compound 2 with PTSA at-20℃ and crystallized from a mixture of V(benzene):V(ligroin)=40:60. Compound 1a was obtained by recycling the catalytic transformation of compound 2 in the mother liquor three times in a accumulative yield of 91.1%.
Based on the condensation reaction of glycerol with benzaldehyde,the effects of acid catalysts (p-toluenesulfonic acid(PTSA), phosphotungstic acid(PWA), KHSO4 and FeCl3,respectively) on the yield of the condensation products and the mass ratio of 5-hydroxyl-2-phenyl-1,3-dioxane(1) to 4-hydroxymethyl-2-phenyl-1,3-dioxolane (2) were investigated. Comparison tests indicated that under the conditions of cyclohexane as water entrainer and n(benzalhydehyde):n(glycerol)=2:3,KHSO4 gave the best yield (96.8%) of condensation products(compound 1+2) and PTSA yielded the highest proportion (m(1):m(2)=48.6:51.4) of compound 1 in condensation products(compound 1+2). At room temperature, PTSA, PWA, KHSO4 and FeCl3 all can,but at -20℃,only PTSA can catalyze the transformation of compound 2 to compound 1. Cis-5-hydroxyl-2-phenyl-1,3-dioxane (1a) was isolated by the catalytic transformation of compound 2 with PTSA at-20℃ and crystallized from a mixture of V(benzene):V(ligroin)=40:60. Compound 1a was obtained by recycling the catalytic transformation of compound 2 in the mother liquor three times in a accumulative yield of 91.1%.
2010, 27(7): 769-772
doi: 10.3724/SP.J.1095.2010.90780
Abstract:
In the present work,epoxidation of styrene with hydrogen peroxide catalyzed by reaction-controlled phase-transfer catalyst of quaternary ammonium heteropolyphosphatotungstate is described. The factors such as solvents,the amount of H2O2,the amount of catalyst,reaction temperature,reaction time,and the concentration of styrene were investigated. It was found that the optimized conditions are ethyl acetate as the solvent,n(styrene):n(H2O2):n(catalyst)=300:300:1,the mass fraction of styrene is 10%,60℃,6 h. Under the optimized conditions,the conversion of styrene is 85.5%,and the selectivity of styrene oxide is 84.9%. The catalyst can be reused with good stability.
In the present work,epoxidation of styrene with hydrogen peroxide catalyzed by reaction-controlled phase-transfer catalyst of quaternary ammonium heteropolyphosphatotungstate is described. The factors such as solvents,the amount of H2O2,the amount of catalyst,reaction temperature,reaction time,and the concentration of styrene were investigated. It was found that the optimized conditions are ethyl acetate as the solvent,n(styrene):n(H2O2):n(catalyst)=300:300:1,the mass fraction of styrene is 10%,60℃,6 h. Under the optimized conditions,the conversion of styrene is 85.5%,and the selectivity of styrene oxide is 84.9%. The catalyst can be reused with good stability.
2010, 27(7): 773-777
doi: 10.3724/SP.J.1095.2010.90712
Abstract:
A mesogenic diacrylate monomer 4,4'-bis[6-(acryloyloxy) hexyloxy] biphenyl (BAB6) was synthesized by two routes. The improved method was from the modified traditional method by substituting 4,4'-bis[6-(bromo) hexyloxy] biphenyl with 4,4'-bis[6-(hydroxyl) hexyloxy] biphenyl to react with acryloyl chloride instead of potassium acrylate. Compared with the traditional method,the reaction temperature was lowered,the solubility of intermediate products was improved and the yield was increased from 12.4% to 46.8%. BAB6 was characterized by 1H NMR,13C NMR and elemental analysis. A fast response polymer dispersed liquid crystal(PDLC) film was casted using BAB6 as the monomer,and the response time was about 2 ms. In addition,the morphology of the polymer network was investigated by SEM.
A mesogenic diacrylate monomer 4,4'-bis[6-(acryloyloxy) hexyloxy] biphenyl (BAB6) was synthesized by two routes. The improved method was from the modified traditional method by substituting 4,4'-bis[6-(bromo) hexyloxy] biphenyl with 4,4'-bis[6-(hydroxyl) hexyloxy] biphenyl to react with acryloyl chloride instead of potassium acrylate. Compared with the traditional method,the reaction temperature was lowered,the solubility of intermediate products was improved and the yield was increased from 12.4% to 46.8%. BAB6 was characterized by 1H NMR,13C NMR and elemental analysis. A fast response polymer dispersed liquid crystal(PDLC) film was casted using BAB6 as the monomer,and the response time was about 2 ms. In addition,the morphology of the polymer network was investigated by SEM.
2010, 27(7): 778-782
doi: 10.3724/SP.J.1095.2010.90549
Abstract:
An efficient one-pot synthesis of amidoalkyl naphthols is described. This involves the three-component Ritter-type reaction of β-naphthol,aromatic aldehyde and amide or urea catalyzed by sulfonic ionic liquid,1-methyl-3-propanesulfonic acid immidazolium hydrogen sulfate[MIMPS] [HSO4]. The results show that under solvent-free condition at 125℃ and n(β-naphthol):n(aromatic aldehyde):n(amide or urea):n([MIMPS] [HSO4])=1:1:1.3:0.1 for 5~40 min,the yield of amidoalkyl naphthols was 85%~97%. The product could be separated simply by filtration after the reaction. The ionic liquid was recycled four times without apparent decrease in catalytic activity. The factors which influenced the multi-component reaction were discussed including the structure of aromatic aldehyde and amide or urea. A possible mechanism was postulated as well.
An efficient one-pot synthesis of amidoalkyl naphthols is described. This involves the three-component Ritter-type reaction of β-naphthol,aromatic aldehyde and amide or urea catalyzed by sulfonic ionic liquid,1-methyl-3-propanesulfonic acid immidazolium hydrogen sulfate[MIMPS] [HSO4]. The results show that under solvent-free condition at 125℃ and n(β-naphthol):n(aromatic aldehyde):n(amide or urea):n([MIMPS] [HSO4])=1:1:1.3:0.1 for 5~40 min,the yield of amidoalkyl naphthols was 85%~97%. The product could be separated simply by filtration after the reaction. The ionic liquid was recycled four times without apparent decrease in catalytic activity. The factors which influenced the multi-component reaction were discussed including the structure of aromatic aldehyde and amide or urea. A possible mechanism was postulated as well.
2010, 27(7): 783-786
doi: 10.3724/SP.J.1095.2010.90575
Abstract:
With toluene,ethylbenzene,cumene,tert-butyl benzene and fluorobenzene as the substrates,the nitration strength(φ) data were recorded when the highest yields of nitration products were obtained in mixed acids. By the method of Density Functional Theory,the groups geometries of nine kinds of aromatic were optimized at the level of B3LYP/6-311G**,and the charge distribution was analyzed. Based on this study,the effects of positioning nine kinds of substituents were investigated,and the relationship between the activity of single-substituted benzene nitration expressed in QRΣC(2~6),and nitrification strength was discussed. Experimental results show that the nitration activity of alkylbenzene,halogen benzene or nitrobenzene has a good linear relationship with the nitration strength(φ) when the highest yield of nitration product is obtained in mixed acid.
With toluene,ethylbenzene,cumene,tert-butyl benzene and fluorobenzene as the substrates,the nitration strength(φ) data were recorded when the highest yields of nitration products were obtained in mixed acids. By the method of Density Functional Theory,the groups geometries of nine kinds of aromatic were optimized at the level of B3LYP/6-311G**,and the charge distribution was analyzed. Based on this study,the effects of positioning nine kinds of substituents were investigated,and the relationship between the activity of single-substituted benzene nitration expressed in QRΣC(2~6),and nitrification strength was discussed. Experimental results show that the nitration activity of alkylbenzene,halogen benzene or nitrobenzene has a good linear relationship with the nitration strength(φ) when the highest yield of nitration product is obtained in mixed acid.
2010, 27(7): 787-791
doi: 10.3724/SP.J.1095.2010.90577
Abstract:
Lignin-tetraethylenepentamine was synthesized from Lignin and tetraethylenepentamine(TEPA) with formaldehyde as a cross-linking agent by Mannich reaction. The prepared complex was used as a matrix to support palladium chloride. Lignin-TEPA-Pd complex was characterized by XPS,TG and DTA,which was an efficient catalyst for the Suzuki reaction of iodobenzene with sodium tetra-phenylboron. The yield of the product was up to 90.2% when the reaction was carried out at 80℃ in air for 8 h with V(DMF):V(H2O)=2:1 mixture as the solvent and NaHCO3 as the base. The catalyst could be separated easily,but the yield of product decreased to 31.3% after 4 times reusage.
Lignin-tetraethylenepentamine was synthesized from Lignin and tetraethylenepentamine(TEPA) with formaldehyde as a cross-linking agent by Mannich reaction. The prepared complex was used as a matrix to support palladium chloride. Lignin-TEPA-Pd complex was characterized by XPS,TG and DTA,which was an efficient catalyst for the Suzuki reaction of iodobenzene with sodium tetra-phenylboron. The yield of the product was up to 90.2% when the reaction was carried out at 80℃ in air for 8 h with V(DMF):V(H2O)=2:1 mixture as the solvent and NaHCO3 as the base. The catalyst could be separated easily,but the yield of product decreased to 31.3% after 4 times reusage.
2010, 27(7): 792-796
doi: 10.3724/SP.J.1095.2010.90653
Abstract:
A new functional resin based on Wang resin was prepared to immobilize the palladium nanoparticles. The application of the supported catalyst in the Suzuki reaction between aryl halides and arylboronic acids in water was described. The influences of the reaction conditions,such as solvent,temperature,base and the amount of the catalyst were investigated with the reaction of bromobenzene and phenylboronic acid as the model. The optimal conditions were found to be:100℃,n(C6H5Br):n(C6H5B (OH)2):n(WRP-Pd):n(K2CO3):n(TBAB)=1.0:1.5:0.005:2.0:0.5 and 4 h. The high yields were obtained through prolongating the reaction time when aromatic chlorides were used as substrates. The catalyst could be reused four times without significant loss in its activity by simple filtration and washing.
A new functional resin based on Wang resin was prepared to immobilize the palladium nanoparticles. The application of the supported catalyst in the Suzuki reaction between aryl halides and arylboronic acids in water was described. The influences of the reaction conditions,such as solvent,temperature,base and the amount of the catalyst were investigated with the reaction of bromobenzene and phenylboronic acid as the model. The optimal conditions were found to be:100℃,n(C6H5Br):n(C6H5B (OH)2):n(WRP-Pd):n(K2CO3):n(TBAB)=1.0:1.5:0.005:2.0:0.5 and 4 h. The high yields were obtained through prolongating the reaction time when aromatic chlorides were used as substrates. The catalyst could be reused four times without significant loss in its activity by simple filtration and washing.
2010, 27(7): 797-800
doi: 10.3724/SP.J.1095.2010.90563
Abstract:
A solid acid SO42-/SnO2-diatomite was prepared by aging of diatomite-Sn(OH)4 sol at 70℃ for 12 h,drying for 12 h at 90℃,impregnating in 3.0 mol/L H2SO4 for 3 h,and calcinating at 550℃ for 3.5 h. The solid acid was characterized by using IR,XRD and TG methods. The sol of diatiomite-Sn(OH)4 was prepared with 1:3 mass ratio of SnCl4·5H2O to diatomite. Then isoamyl butyrate was synthesized from n-butyric acid and isoamyl alcohol in the presence of the composite solid acid as the catalyst. Effects of catalyst dosage,molar ratio of isoamyl alcohol to n-butyric acid,reaction time,and type of water entrainer on the yield of isoamyl butyrate (IAB) were examed. Under the optimized reaction conditions,n(isoamyl alcohol):n(n-butyric acid)=1.4:1,reaction time in 70 min,benzene 10 mL,and the mass fraction of catalyst in total mass of reactants 2.5%,the yield of IAB was 97.7%. Compared with multi-composite solid acid and SO42-/clay,the prepared catalyst possesses advantages of low cost,high activity,facile preparation and easy separation from the reaction system. It can be reused to a certain extent.
A solid acid SO42-/SnO2-diatomite was prepared by aging of diatomite-Sn(OH)4 sol at 70℃ for 12 h,drying for 12 h at 90℃,impregnating in 3.0 mol/L H2SO4 for 3 h,and calcinating at 550℃ for 3.5 h. The solid acid was characterized by using IR,XRD and TG methods. The sol of diatiomite-Sn(OH)4 was prepared with 1:3 mass ratio of SnCl4·5H2O to diatomite. Then isoamyl butyrate was synthesized from n-butyric acid and isoamyl alcohol in the presence of the composite solid acid as the catalyst. Effects of catalyst dosage,molar ratio of isoamyl alcohol to n-butyric acid,reaction time,and type of water entrainer on the yield of isoamyl butyrate (IAB) were examed. Under the optimized reaction conditions,n(isoamyl alcohol):n(n-butyric acid)=1.4:1,reaction time in 70 min,benzene 10 mL,and the mass fraction of catalyst in total mass of reactants 2.5%,the yield of IAB was 97.7%. Compared with multi-composite solid acid and SO42-/clay,the prepared catalyst possesses advantages of low cost,high activity,facile preparation and easy separation from the reaction system. It can be reused to a certain extent.
2010, 27(7): 801-805
doi: 10.3724/SP.J.1095.2010.90669
Abstract:
Three manganese oxide octahedral molecular sieves(OMS-2),K-OMS-2,H-K-OMS-2 and Cu-OMS-2,were synthesized according to the literature. The structure and composition of the obtained materials were characterized by SEM and XRD. OMS-2 was applied to the selective oxidation of alcohols to generate corresponding aldehydes or ketones. The effects of reaction time and temperature on the catalytic reactions were investigated in ionic liquid [bmim]PF6 when different OMS-2 materials were used as catalysts. The conversion and selectivity of benzylic or allylic alcohols catalyzed by H-K-OMS-2 both reached over 90%. The solvent and catalyst could be recovered from the reaction system by extraction method and vacuum distillation method,respectively. The catalytic system recovered by vacuum distillation method showed better recycling performance.
Three manganese oxide octahedral molecular sieves(OMS-2),K-OMS-2,H-K-OMS-2 and Cu-OMS-2,were synthesized according to the literature. The structure and composition of the obtained materials were characterized by SEM and XRD. OMS-2 was applied to the selective oxidation of alcohols to generate corresponding aldehydes or ketones. The effects of reaction time and temperature on the catalytic reactions were investigated in ionic liquid [bmim]PF6 when different OMS-2 materials were used as catalysts. The conversion and selectivity of benzylic or allylic alcohols catalyzed by H-K-OMS-2 both reached over 90%. The solvent and catalyst could be recovered from the reaction system by extraction method and vacuum distillation method,respectively. The catalytic system recovered by vacuum distillation method showed better recycling performance.
2010, 27(7): 806-810
doi: 10.3724/SP.J.1095.2010.90660
Abstract:
A new potassium compound of 4-iodo-3,5-dimethyl-pyrazole was synthesized with acetylacetone and hydrazine hydrate as the starting materials via oximation,condensation cyclization, reduction, diazotization and iodination. The compound was characterized by elemental analysis,IR,and 1H NMR. The reaction mechanism of oximation was studied with the program of Gaussian 03,at the MP2/6-311 ++ G(d,p) level. The stable geometric configurations of acetylacetone-3-oxime(1) and its intermediate of 4-hydroxy-3-nitrosopent-3-en-2-one(1b) were confirmed at the same calculation level. Furthermore,the crystal structure was determined by single-crystal X-ray diffraction analysis. The crystal is monoclinic,P21/c space group,with crystal parameters a=0.77645(10) nm, b=2.0361(2) nm, c=1.05761(13) nm, β=107.806(2)°, V=1591.9(3) nm3, Z=4, Dc=2.012 g/cm3, F(000)=904,R1=0.0398.
A new potassium compound of 4-iodo-3,5-dimethyl-pyrazole was synthesized with acetylacetone and hydrazine hydrate as the starting materials via oximation,condensation cyclization, reduction, diazotization and iodination. The compound was characterized by elemental analysis,IR,and 1H NMR. The reaction mechanism of oximation was studied with the program of Gaussian 03,at the MP2/6-311 ++ G(d,p) level. The stable geometric configurations of acetylacetone-3-oxime(1) and its intermediate of 4-hydroxy-3-nitrosopent-3-en-2-one(1b) were confirmed at the same calculation level. Furthermore,the crystal structure was determined by single-crystal X-ray diffraction analysis. The crystal is monoclinic,P21/c space group,with crystal parameters a=0.77645(10) nm, b=2.0361(2) nm, c=1.05761(13) nm, β=107.806(2)°, V=1591.9(3) nm3, Z=4, Dc=2.012 g/cm3, F(000)=904,R1=0.0398.
2010, 27(7): 811-816
doi: 10.3724/SP.J.1095.2010.90595
Abstract:
The adsorption of low-substituted cationic starch(CS-L) on Mg-Al HTlc was investigated. The following results were obtained: CS-L can be adsorbed on the external surface of positively changed Mg-Al HTlc. The adsorption isotherm followed the typical Langmuir equation and the saturated adsorption amount was 33.92 mg/g. The driving force for adsorption was probably due to two effects:(1) hydrogen bonding between the hydroxyl group or ether group of CS-L and the hydroxyl group of HTlc; (2) entropic effect,where the entropic loss for the CS-L adsorption is less then entropic gain for the released solvent molecules. The adsorption amount of CS-L increased with pH,which may be contributed to the decrease of the zeta potentials of CS-L and the HTlc with pH. The adsorption amount of CS-L increased with the addition of NaCl and CaCl2 because inert electrolytes screened the repulsion between HTlc particles and CS-L and the intra-molecular repulsion between the cationic groups of the CS-L. At pH=9,the adsorption of CS-L on HTlc increased dramatically with the concentration of AlCl3 since the hydrolysate of Al3+ might play a role as a linkage between CS-L and HTlc,and. The adsorption amount of CS-L decreased with increasing temperature as a result of hydrogen bonding decrease. The adsorption kinetics of CS-L on Mg-Al HTlc showed that the equilibrium time of adsorption was about 300 min. Furthermore,the comparison of adsorption behaviors between CS-L and CS-H on Mg-Al HTlc was also carried out.
The adsorption of low-substituted cationic starch(CS-L) on Mg-Al HTlc was investigated. The following results were obtained: CS-L can be adsorbed on the external surface of positively changed Mg-Al HTlc. The adsorption isotherm followed the typical Langmuir equation and the saturated adsorption amount was 33.92 mg/g. The driving force for adsorption was probably due to two effects:(1) hydrogen bonding between the hydroxyl group or ether group of CS-L and the hydroxyl group of HTlc; (2) entropic effect,where the entropic loss for the CS-L adsorption is less then entropic gain for the released solvent molecules. The adsorption amount of CS-L increased with pH,which may be contributed to the decrease of the zeta potentials of CS-L and the HTlc with pH. The adsorption amount of CS-L increased with the addition of NaCl and CaCl2 because inert electrolytes screened the repulsion between HTlc particles and CS-L and the intra-molecular repulsion between the cationic groups of the CS-L. At pH=9,the adsorption of CS-L on HTlc increased dramatically with the concentration of AlCl3 since the hydrolysate of Al3+ might play a role as a linkage between CS-L and HTlc,and. The adsorption amount of CS-L decreased with increasing temperature as a result of hydrogen bonding decrease. The adsorption kinetics of CS-L on Mg-Al HTlc showed that the equilibrium time of adsorption was about 300 min. Furthermore,the comparison of adsorption behaviors between CS-L and CS-H on Mg-Al HTlc was also carried out.
2010, 27(7): 817-822
doi: 10.3724/SP.J.1095.2010.90668
Abstract:
Polythioether type cotton cellulose (PTCC),a functional material,was synthesized by the etherification of cotton cellulose and chloromethylthiirane in an alkaline medium. The effect of pH on adsorption capacity of PTCC for cationic dyes was investigated. The adsorption kinetics and thermodynamics of cationic dyes on PTCC were studied. The experimental results show that neutral condition favored the adsorption. At 298 K,pH=7.0,the adsorption approached to equilibrium in 2 h,the saturated adsorption capacities of PTCC for basic Blue B,basic Blue R and night blue were 726,652 and 320 mg/g,respectively. The adsorption of cationic dyes on PTCC followed the second-order kinetic model,the adsorption rate constant k2 increased with the decrease of temperature,indicating that low temperature favors the adsorption. The negative values of △G,△H and △S suggest that the adsorptions are spontaneous and exothermic processes,which were achieved mainly by Vander Waals force. The adsorption isotherms fit well with the Langmuir equation,which can be explained as a monolayer adsorption.
Polythioether type cotton cellulose (PTCC),a functional material,was synthesized by the etherification of cotton cellulose and chloromethylthiirane in an alkaline medium. The effect of pH on adsorption capacity of PTCC for cationic dyes was investigated. The adsorption kinetics and thermodynamics of cationic dyes on PTCC were studied. The experimental results show that neutral condition favored the adsorption. At 298 K,pH=7.0,the adsorption approached to equilibrium in 2 h,the saturated adsorption capacities of PTCC for basic Blue B,basic Blue R and night blue were 726,652 and 320 mg/g,respectively. The adsorption of cationic dyes on PTCC followed the second-order kinetic model,the adsorption rate constant k2 increased with the decrease of temperature,indicating that low temperature favors the adsorption. The negative values of △G,△H and △S suggest that the adsorptions are spontaneous and exothermic processes,which were achieved mainly by Vander Waals force. The adsorption isotherms fit well with the Langmuir equation,which can be explained as a monolayer adsorption.
2010, 27(7): 823-828
doi: 10.3724/SP.J.1095.2010.90627
Abstract:
Ethylene sulfate(DTD) was studied as an additive to 1 mol/L LiPF6/ethylene carbonate(EC) + dimethyl carbonate(DMC) + methyl ethyl carbonate(EMC) (1:1:1 by volume) electrolyte for lithium ion batteries. The effects of DTD on lithium ion battery performance and on the mesocarbon microbead(MCMB) electrode/electrolyte interphase were investigated by galvanostatic charge-discharge measurements,cyclic voltammetry(CV),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS) and electro-chemical impedance spectroscopy (EIS). The results show that DTD with a volume ratio of 0.01% can increase the reversible discharge capacity(from 300 mA·h/g to 350 mA·h/g) and cycleability of MCMB/Li cell. SEM observation and EIS analysis suggest that DTD facilitates the morphology of solid electrolyte interface(SEI) formed on the surface of the MCMB electrode and reduces the total resistance of the cell. CV measurements reveal that DTD can be electrochemically reduced at potentials around 1.4 V(vs Li/Li+) during the first reduction engaged in the formation of SEI. At the same time,DTD has no adverse effect on the LiMn2O4 electrode.
Ethylene sulfate(DTD) was studied as an additive to 1 mol/L LiPF6/ethylene carbonate(EC) + dimethyl carbonate(DMC) + methyl ethyl carbonate(EMC) (1:1:1 by volume) electrolyte for lithium ion batteries. The effects of DTD on lithium ion battery performance and on the mesocarbon microbead(MCMB) electrode/electrolyte interphase were investigated by galvanostatic charge-discharge measurements,cyclic voltammetry(CV),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS) and electro-chemical impedance spectroscopy (EIS). The results show that DTD with a volume ratio of 0.01% can increase the reversible discharge capacity(from 300 mA·h/g to 350 mA·h/g) and cycleability of MCMB/Li cell. SEM observation and EIS analysis suggest that DTD facilitates the morphology of solid electrolyte interface(SEI) formed on the surface of the MCMB electrode and reduces the total resistance of the cell. CV measurements reveal that DTD can be electrochemically reduced at potentials around 1.4 V(vs Li/Li+) during the first reduction engaged in the formation of SEI. At the same time,DTD has no adverse effect on the LiMn2O4 electrode.
2010, 27(7): 829-835
doi: 10.3724/SP.J.1095.2010.90433
Abstract:
Mixtures of nanogold sol(NGS) and multi-walled carbon nanotubes(MWCNTs) were used as a carrier for laccase immobilization. Three immobilization approaches were evaluated via comparing the amount of immobilized laccase and their specific activity of immobilized enzyme. Thermal stability and reusability of immobilized laccase were investigated and the effects of particle size of nanogold sol particles on laccase immobilization and immobilized enzyme kinetics were examined. Results from experiments reveal that NGS/MWCNTs matrices have the most excellent capability of laccase immobilization and high specific activity of immobilized laccase. Amount of immobilized enzyme and specific activity reach 33.80 mg/g and 9.433 U/mg,respectively,through simple physical adsorption when NGS particle size is 37 nm. It is also shown that the strategy of physical adsorption is suitable for immobilization of laccase in practice according to comprehensive evaluation of the amount of immobilized laccase,thermal stability,specific activity and reusability. Immobilized laccase on NGS/MWCNTs through covalent coupling can retain about 75% of initial activity after 2 h at 70℃ and retain 70% of initial activity after 20 recycles of repeated use. Conclusion from experiments indicates smaller NGS particle(24 nm) makes the affinity between immobilized laccase and its substrate(KM=0.027 mmol/L) stronger and the apparent catalyzing rate constant(1088 min -1) greater.
Mixtures of nanogold sol(NGS) and multi-walled carbon nanotubes(MWCNTs) were used as a carrier for laccase immobilization. Three immobilization approaches were evaluated via comparing the amount of immobilized laccase and their specific activity of immobilized enzyme. Thermal stability and reusability of immobilized laccase were investigated and the effects of particle size of nanogold sol particles on laccase immobilization and immobilized enzyme kinetics were examined. Results from experiments reveal that NGS/MWCNTs matrices have the most excellent capability of laccase immobilization and high specific activity of immobilized laccase. Amount of immobilized enzyme and specific activity reach 33.80 mg/g and 9.433 U/mg,respectively,through simple physical adsorption when NGS particle size is 37 nm. It is also shown that the strategy of physical adsorption is suitable for immobilization of laccase in practice according to comprehensive evaluation of the amount of immobilized laccase,thermal stability,specific activity and reusability. Immobilized laccase on NGS/MWCNTs through covalent coupling can retain about 75% of initial activity after 2 h at 70℃ and retain 70% of initial activity after 20 recycles of repeated use. Conclusion from experiments indicates smaller NGS particle(24 nm) makes the affinity between immobilized laccase and its substrate(KM=0.027 mmol/L) stronger and the apparent catalyzing rate constant(1088 min -1) greater.
2010, 27(7): 836-841
doi: 10.3724/SP.J.1095.2010.90692
Abstract:
The synergistic inhibition effect of rare earth Ce4+ and vanillin (4-hydroxy-3-methoxy-benzaldehyde) on the corrosion of cold rolled steel(CRS) in 3.0 mol/L H3PO4 solution was studied by mass loss,potentiodynamic polarization and UV-Vis spectrophotometry(UV-Vis). The present study reveals that vanillin exhibits a moderate inhibitive effect on the corrosion of CRS. The inhibition efficiency(IE) increases with the concentration increase,and the maximum IE is 66%. The adsorption of vanillin on the CRS surface obeys Freundlich adsorption isotherm equation. Ce4+ shows a poor inhibition performance and the maximum IE is not more than 20%. However,incorporation of rare earth Ce4+ with vanillin significantly improves the inhibition performance and produces a synergistic inhibition effect. The maximum IE is as high as 90%. Ce4+ and vanillin form a new complex,which acts as a mixed-type inhibitor.
The synergistic inhibition effect of rare earth Ce4+ and vanillin (4-hydroxy-3-methoxy-benzaldehyde) on the corrosion of cold rolled steel(CRS) in 3.0 mol/L H3PO4 solution was studied by mass loss,potentiodynamic polarization and UV-Vis spectrophotometry(UV-Vis). The present study reveals that vanillin exhibits a moderate inhibitive effect on the corrosion of CRS. The inhibition efficiency(IE) increases with the concentration increase,and the maximum IE is 66%. The adsorption of vanillin on the CRS surface obeys Freundlich adsorption isotherm equation. Ce4+ shows a poor inhibition performance and the maximum IE is not more than 20%. However,incorporation of rare earth Ce4+ with vanillin significantly improves the inhibition performance and produces a synergistic inhibition effect. The maximum IE is as high as 90%. Ce4+ and vanillin form a new complex,which acts as a mixed-type inhibitor.
2010, 27(7): 842-848
doi: 10.3724/SP.J.1095.2010.90649
Abstract:
In a pH 2.5~4.0 Britton-Robinson(BR) buffer medium,some proteins such as bovine serum albumin(BSA),Chymotrypsin(Chy) and α-amylase(α-Amy) can react with chondroitin sulfate A(CS) via electrostatic force,hydrogen bond force or/and hydrophobic force to form binding products. As a result,the resonance Rayleigh scattering(RRS),second-order scattering(SOS) and frequency doubling scattering(FDS) were enhanced greatly with new scattering spectra appeared. The increments of scattering intensity(△I) were proportional to the concentration of CS in certain ranges. The detection limits(3σ) of CS in Chy,BSA and α-Amy systems were 1.4,2.0 and 1.8 μg/L(RRS method),2.3,2.9 and 2.5 μg/L(SOS method),5.8,13.2 and 9.6 μg/L (FDS method),respectively. Among them,the RRS method exhibited the highest sensitivity and the Chy-CS system was more sensitive than others. The characteristics of the spectra and optimal conditions of RRS method were investigated. The effects of external substances were tested. The established methods have a good selectivity and can be applied to the determination of CS in eye drops with satisfactory results.
In a pH 2.5~4.0 Britton-Robinson(BR) buffer medium,some proteins such as bovine serum albumin(BSA),Chymotrypsin(Chy) and α-amylase(α-Amy) can react with chondroitin sulfate A(CS) via electrostatic force,hydrogen bond force or/and hydrophobic force to form binding products. As a result,the resonance Rayleigh scattering(RRS),second-order scattering(SOS) and frequency doubling scattering(FDS) were enhanced greatly with new scattering spectra appeared. The increments of scattering intensity(△I) were proportional to the concentration of CS in certain ranges. The detection limits(3σ) of CS in Chy,BSA and α-Amy systems were 1.4,2.0 and 1.8 μg/L(RRS method),2.3,2.9 and 2.5 μg/L(SOS method),5.8,13.2 and 9.6 μg/L (FDS method),respectively. Among them,the RRS method exhibited the highest sensitivity and the Chy-CS system was more sensitive than others. The characteristics of the spectra and optimal conditions of RRS method were investigated. The effects of external substances were tested. The established methods have a good selectivity and can be applied to the determination of CS in eye drops with satisfactory results.
2010, 27(7): 849-854
doi: 10.3724/SP.J.1095.2010.90604
Abstract:
The resonance light scattering(RLS) spectra of Ru(bpy)2(dppx)2+-SDS-DNA(bpy=2,2'-bipyridine; dppx=7,8-dimethyl-dipyrido[3,2-a:2',3'-c] phenazine) system was studied. The results show that the solution of Ru(bpy)2(dppx)2+-SDS exhibits a high RLS signal in the presence of the premicellar aggregation of an anionic surfactant,sodium dodecyl sulphate(SDS),and adding DNA in the solution of Ru(bpy)2(dppx)2+-SDS results in the quenching of the RLS. The mechanism of the reaction was explored. Based on the quenching effect of DNA on the RLS of Ru(bpy)2(dppx)2+-SDS system,a novel RLS method for the determination of DNA was proposed. Under optimal conditions,the quenched intensity of RLS at 393 nm is proportional to the concentration of DNA. The linear range of the determination is 0.01~1.2 mg/L. The detection limit is 1.5 μg/L. This method was successful applied to the determination of DNA in synthetic and real samples.
The resonance light scattering(RLS) spectra of Ru(bpy)2(dppx)2+-SDS-DNA(bpy=2,2'-bipyridine; dppx=7,8-dimethyl-dipyrido[3,2-a:2',3'-c] phenazine) system was studied. The results show that the solution of Ru(bpy)2(dppx)2+-SDS exhibits a high RLS signal in the presence of the premicellar aggregation of an anionic surfactant,sodium dodecyl sulphate(SDS),and adding DNA in the solution of Ru(bpy)2(dppx)2+-SDS results in the quenching of the RLS. The mechanism of the reaction was explored. Based on the quenching effect of DNA on the RLS of Ru(bpy)2(dppx)2+-SDS system,a novel RLS method for the determination of DNA was proposed. Under optimal conditions,the quenched intensity of RLS at 393 nm is proportional to the concentration of DNA. The linear range of the determination is 0.01~1.2 mg/L. The detection limit is 1.5 μg/L. This method was successful applied to the determination of DNA in synthetic and real samples.
2010, 27(7): 855-859
doi: 10.3724/SP.J.1095.2010.90634
Abstract:
In a Britton-Robinson(BR) buffer solution of pH=4.0,erythrosine reacted with tetracaine hydrochloride(TC·HCl) to form a 1:1 ion-association complex. As a result the absorption spectra of solution changed,and an obvious fading peak at 516 nm and a coloring revealing peak at 558 nm appeared. In the range of 0.1 × 10-6 to 7.2 × 10-6 g/mL,there is linearity between the concentration of TC·HCl and absorbency of the solution at the fading peak and coloring revealing peak. Based on it,a new spectrophotometry for the determination of TC·HCl was proposed. The molar absorptivity is 3.30 × 104L/(mol·cm) for the fading method,2.22 × 104L/(mol·cm) for the revealing method and 5.52 × 104L/(mol·cm) for the dualwavelength method. The optimum reaction conditions and primary chemistry characteristics were discussed. The reaction mechanism was dicussed by quantum chemistry AM1 method. The method has been applied to the determination of TC·HCl in human serum and urine samples with satisfactory results. The mean recovery is from 98.1% to 103.3%.
In a Britton-Robinson(BR) buffer solution of pH=4.0,erythrosine reacted with tetracaine hydrochloride(TC·HCl) to form a 1:1 ion-association complex. As a result the absorption spectra of solution changed,and an obvious fading peak at 516 nm and a coloring revealing peak at 558 nm appeared. In the range of 0.1 × 10-6 to 7.2 × 10-6 g/mL,there is linearity between the concentration of TC·HCl and absorbency of the solution at the fading peak and coloring revealing peak. Based on it,a new spectrophotometry for the determination of TC·HCl was proposed. The molar absorptivity is 3.30 × 104L/(mol·cm) for the fading method,2.22 × 104L/(mol·cm) for the revealing method and 5.52 × 104L/(mol·cm) for the dualwavelength method. The optimum reaction conditions and primary chemistry characteristics were discussed. The reaction mechanism was dicussed by quantum chemistry AM1 method. The method has been applied to the determination of TC·HCl in human serum and urine samples with satisfactory results. The mean recovery is from 98.1% to 103.3%.
2010, 27(7): 860-862
doi: 10.3724/SP.J.1095.2010.90633
Abstract:
Cyanophyll was prepared from the reaction of acetal with benzyl alcohol in the presence of sulfonic acidic ionic liquid 1-(4-sulfonic group) butyl-3-methylimidazole tetrafluoroborate([4-sulfbmim] [BF4]) as acidic catalyst. At reaction temperature 20℃,the reaction conditions were optimized by orthogonal experiments as follows,molar ratio of benzyl alcohol and acetal is 1 to 8,reaction time 60 min,amount of catalyst 4 g based on benzyl alcohol. The yield of cyanophyll could be 92.2%. The acidic ionic liquid[4-sulfbmim] [BF4]had better catalytic effect compared with H2SO4 even if it is a little weaker in activity,and it could be reused for 6 times without losing of the catalytic activity.
Cyanophyll was prepared from the reaction of acetal with benzyl alcohol in the presence of sulfonic acidic ionic liquid 1-(4-sulfonic group) butyl-3-methylimidazole tetrafluoroborate([4-sulfbmim] [BF4]) as acidic catalyst. At reaction temperature 20℃,the reaction conditions were optimized by orthogonal experiments as follows,molar ratio of benzyl alcohol and acetal is 1 to 8,reaction time 60 min,amount of catalyst 4 g based on benzyl alcohol. The yield of cyanophyll could be 92.2%. The acidic ionic liquid[4-sulfbmim] [BF4]had better catalytic effect compared with H2SO4 even if it is a little weaker in activity,and it could be reused for 6 times without losing of the catalytic activity.
2010, 27(7): 863-865
doi: 10.3724/SP.J.1095.2010.90639
Abstract:
(S)-Benzyl-2-(benzyloxycarbonylamino)-4-oxobutanoate was synthesized from L-methionine via methylation reaction,hydrolysis,carboxyl and amino protection,pyridinium chorochromate(PCC) oxidation. The structure of the target product was characterized by means of 1H NMR,IR and MS. The optical purity was determined by HPLC and polarimeter method. The overall yield was 30.0%. The purity and ee value of the target compound were 99.3% and 99.5%,respectively.
(S)-Benzyl-2-(benzyloxycarbonylamino)-4-oxobutanoate was synthesized from L-methionine via methylation reaction,hydrolysis,carboxyl and amino protection,pyridinium chorochromate(PCC) oxidation. The structure of the target product was characterized by means of 1H NMR,IR and MS. The optical purity was determined by HPLC and polarimeter method. The overall yield was 30.0%. The purity and ee value of the target compound were 99.3% and 99.5%,respectively.
2010, 27(7): 866-868
doi: 10.3724/SP.J.1095.2010.90661
Abstract:
Cashew phenol polyoxyethylene ethers (CPE) were synthesized from cashew phenol as raw materials. In the presence of sodium hydroxide as a catalyst,a series of cashew phenol polyoxyethylene ether carboxylates(CPEC) were synthesized with CPE and chloroacetic acid. The products were structurally confirmed by FT-IR and elemental analysis. Surface properties were determined by a surface tension method. The experimental results showed that when critical micelle concentrations(CMC) of the surfactants were 9.30,8.50,8.10 and 7.71 mmol/L,the corresponding surface tensions at CMC were 28.38,28.60,30.40 and 30.00 mN/m,respectively. By means of Gibbs formula,the maximum adsorption amounts of the surfactants were 0.7087,0.7350,0.7195 and 0.7346 μmol/m2,and the minimal molecular projective areas of them were 2.3439,2.2600,2.3087 and 2.2613 nm2,respectively,on solution surface.
Cashew phenol polyoxyethylene ethers (CPE) were synthesized from cashew phenol as raw materials. In the presence of sodium hydroxide as a catalyst,a series of cashew phenol polyoxyethylene ether carboxylates(CPEC) were synthesized with CPE and chloroacetic acid. The products were structurally confirmed by FT-IR and elemental analysis. Surface properties were determined by a surface tension method. The experimental results showed that when critical micelle concentrations(CMC) of the surfactants were 9.30,8.50,8.10 and 7.71 mmol/L,the corresponding surface tensions at CMC were 28.38,28.60,30.40 and 30.00 mN/m,respectively. By means of Gibbs formula,the maximum adsorption amounts of the surfactants were 0.7087,0.7350,0.7195 and 0.7346 μmol/m2,and the minimal molecular projective areas of them were 2.3439,2.2600,2.3087 and 2.2613 nm2,respectively,on solution surface.
