Login In
2001 Volume 18 Issue 4
2001, 18(4): 259-263
Abstract:
The FTIR spectrometry was used to determining the total degree of substitution (DS1) of phthaloyl chitosans(PHCS) and degree of substitution of phthaloyl imide groups(DS2). The probe bands, reference bands and baselines in IR spectra were investigated for the determination. The DSs were also determined by 1H NMR and elemental analysis for comparison. Based on the average relative deviations of (Aprobe band/Aref band) to DS in FTIR spectra the most suitable APB/ARB) was found to be A1712BL1/A1391BL3 for DS1 calculation, and A1775BL1/A1654BL1 for DS2, where BL1, BL2 and BL3 are the baselines in IR spectra(Fig.1).
The FTIR spectrometry was used to determining the total degree of substitution (DS1) of phthaloyl chitosans(PHCS) and degree of substitution of phthaloyl imide groups(DS2). The probe bands, reference bands and baselines in IR spectra were investigated for the determination. The DSs were also determined by 1H NMR and elemental analysis for comparison. Based on the average relative deviations of (Aprobe band/Aref band) to DS in FTIR spectra the most suitable APB/ARB) was found to be A1712BL1/A1391BL3 for DS1 calculation, and A1775BL1/A1654BL1 for DS2, where BL1, BL2 and BL3 are the baselines in IR spectra(Fig.1).
2001, 18(4): 264-268
Abstract:
Nanosize T-PbO particles were prepared by one step solid state reaction of Pb(Ⅱ) compounds with NaOH at room temperature and characterized by XRD and TEM techniques. The formation mechanism of nanophase materials was discussed. The T-PbO modified MnO2 electrodes were fabricated and their electrochemical properties were studied by using constant current deep discharging tests. The results indicate that the optimal portions of T-PbO additives were 1.25%~5.00%. The discharge capacity of the nanophase T-PbO modified MnO2 electrodes were in average 50% higher than that of International Common Sample No.1 electrolytic manganese dioxide and 20% higher than that of normal T-PbO particle modified MnO2 electrodes in middle load discharging. The most high discharge capacity was observed for modified MnO2 electrode at heavy load discharging.
Nanosize T-PbO particles were prepared by one step solid state reaction of Pb(Ⅱ) compounds with NaOH at room temperature and characterized by XRD and TEM techniques. The formation mechanism of nanophase materials was discussed. The T-PbO modified MnO2 electrodes were fabricated and their electrochemical properties were studied by using constant current deep discharging tests. The results indicate that the optimal portions of T-PbO additives were 1.25%~5.00%. The discharge capacity of the nanophase T-PbO modified MnO2 electrodes were in average 50% higher than that of International Common Sample No.1 electrolytic manganese dioxide and 20% higher than that of normal T-PbO particle modified MnO2 electrodes in middle load discharging. The most high discharge capacity was observed for modified MnO2 electrode at heavy load discharging.
2001, 18(4): 269-271
Abstract:
Carbon nanotubes and graphite were mixed and used as anode material for lithium ion battery. A great many of nano-scale pores were formed between carbon nanotubes and graphite, improving the charge-discharge capacity of the mixture. Moreover,as a bridge, the carbon nanotubes could improve the property of electric conduction and avoid the effect of isolated island during the lithium intercalation and de-intercalation. The reversible capacity of the anode materials on first cycle was 341 8 mA·h/g, and maintained at 94 5% after 10 cycles. The charge-discharge behavior of the mixed materials was better than that of the single carbon nanotubes or graphite.
Carbon nanotubes and graphite were mixed and used as anode material for lithium ion battery. A great many of nano-scale pores were formed between carbon nanotubes and graphite, improving the charge-discharge capacity of the mixture. Moreover,as a bridge, the carbon nanotubes could improve the property of electric conduction and avoid the effect of isolated island during the lithium intercalation and de-intercalation. The reversible capacity of the anode materials on first cycle was 341 8 mA·h/g, and maintained at 94 5% after 10 cycles. The charge-discharge behavior of the mixed materials was better than that of the single carbon nanotubes or graphite.
2001, 18(4): 272-275
Abstract:
The effects of temperature, concentrations of initiator (KPS) and emulsifier (SDS) on emulsion polymerization of 2,5 dimethoxyaniline (DMAn) were investigated. The polymer PDMAn with number average molecualr weight of 1.22×104 was obtained in the conditions, [monomer]=6.0×10-3 mol/L, [SDS]≥5.0×10-2 mol/L, [KPS]=3.5×10-3 mol/L, 85℃, for 2.0 h. 1H NMR, FTIR and TEM techniques were used in structure characterization, the results showed that the polymer was produced by para polymerization and the ratio of benzoid to quinoid units was 3:1 in its macromolecular chain.
The effects of temperature, concentrations of initiator (KPS) and emulsifier (SDS) on emulsion polymerization of 2,5 dimethoxyaniline (DMAn) were investigated. The polymer PDMAn with number average molecualr weight of 1.22×104 was obtained in the conditions, [monomer]=6.0×10-3 mol/L, [SDS]≥5.0×10-2 mol/L, [KPS]=3.5×10-3 mol/L, 85℃, for 2.0 h. 1H NMR, FTIR and TEM techniques were used in structure characterization, the results showed that the polymer was produced by para polymerization and the ratio of benzoid to quinoid units was 3:1 in its macromolecular chain.
2001, 18(4): 276-280
Abstract:
The extraction of gold from alkaline cyanide solution by alkyl-substituted secondary amine has been investigated. The effects of several variables, such as equilibrium time, temperature, diluent, extractant concentration, pH, gold concentration, ionic strength of the aqueous phase and phase ratio (O/A) on the extraction yield are discussed. The extraction isotherm, saturation capacity, separation coefficients of gold to silver (Ⅰ), ferrous (Ⅱ), copper (Ⅰ), nickel (Ⅱ), zinc(Ⅱ) have been determined respectively. Stripping extraction of gold from loaded organic phase has also been studied. The results showed that the system consisted of 0.1%(volume fraction) secondary amine(7203)-0.05% (volume fraction)ROH-n-dodecane gave high extraction yield and selectivity for Au(CN)2 at pH1/2=11.7.
The extraction of gold from alkaline cyanide solution by alkyl-substituted secondary amine has been investigated. The effects of several variables, such as equilibrium time, temperature, diluent, extractant concentration, pH, gold concentration, ionic strength of the aqueous phase and phase ratio (O/A) on the extraction yield are discussed. The extraction isotherm, saturation capacity, separation coefficients of gold to silver (Ⅰ), ferrous (Ⅱ), copper (Ⅰ), nickel (Ⅱ), zinc(Ⅱ) have been determined respectively. Stripping extraction of gold from loaded organic phase has also been studied. The results showed that the system consisted of 0.1%(volume fraction) secondary amine(7203)-0.05% (volume fraction)ROH-n-dodecane gave high extraction yield and selectivity for Au(CN)2 at pH1/2=11.7.
2001, 18(4): 281-285
Abstract:
The title complex was synthesized in an aqueous solution (pH=4~5). Its single crystal was obtained by slow evaporation and characterized by IR, XRD and thermal analysis. The crystal belongs to orthorhombic with a space group P212121:a=1.1960(2) nm, b=3.0 789(6) nm, c=0.47 652(10) nm, Z=4, Dc=1.987 g/cm3. The crystal is a one-dimentional chain complex. The neighboring two Gd3+ ions are connected by two simple bridged carboxyl groups and a _2-bridging carboxyl group. Each Gd3+ ion is simuetaneosly coordinated by two water molecules. So the coordination number of Gd3+ is nine, forming a coordination polyhedron of distorted mono capped square antiprism. The coordination polyhedron is the first reported example for rare earth glycine (1:3) complexes. The bond enthalpies of coordination bonds were gained for the title complex.
The title complex was synthesized in an aqueous solution (pH=4~5). Its single crystal was obtained by slow evaporation and characterized by IR, XRD and thermal analysis. The crystal belongs to orthorhombic with a space group P212121:a=1.1960(2) nm, b=3.0 789(6) nm, c=0.47 652(10) nm, Z=4, Dc=1.987 g/cm3. The crystal is a one-dimentional chain complex. The neighboring two Gd3+ ions are connected by two simple bridged carboxyl groups and a _2-bridging carboxyl group. Each Gd3+ ion is simuetaneosly coordinated by two water molecules. So the coordination number of Gd3+ is nine, forming a coordination polyhedron of distorted mono capped square antiprism. The coordination polyhedron is the first reported example for rare earth glycine (1:3) complexes. The bond enthalpies of coordination bonds were gained for the title complex.
2001, 18(4): 286-289
Abstract:
The mixed ligand complexes of [Ni(dmit)(dmise)]n- (n=2,1,0) were synthesized. The charge transfer salt of [BEDT-TTF][Ni(dmit)(dmise)] was prepared by electrocrystallization. The products were characterized by EA, IR and ESR. The electrical conductivities of [Ni(dmit)(dmise)] and [BEDT-TTF][Ni(dmit)(dmise)] at 25℃ were measured to be 0.29 and 5 6×10-3Ω-1cm-1, respectively. The temperature dependence of electrical conductivity shows that [Ni(dmit)(dmise)] displays semi-conductor properties.
The mixed ligand complexes of [Ni(dmit)(dmise)]n- (n=2,1,0) were synthesized. The charge transfer salt of [BEDT-TTF][Ni(dmit)(dmise)] was prepared by electrocrystallization. The products were characterized by EA, IR and ESR. The electrical conductivities of [Ni(dmit)(dmise)] and [BEDT-TTF][Ni(dmit)(dmise)] at 25℃ were measured to be 0.29 and 5 6×10-3Ω-1cm-1, respectively. The temperature dependence of electrical conductivity shows that [Ni(dmit)(dmise)] displays semi-conductor properties.
2001, 18(4): 290-294
Abstract:
A silica supported catalyst, CoSalen (Co(Ⅱ) complex of bis (salicylideneethylene diamine)) coordinated with chitosan (SiO2-CS-CoSalen), was prepared. The chitosan film coated on the silica surface was characterized through elemental analysis, IR, fluorescence spectrophotometry, ESR and XPS. It is found that the coordination is realized through binding of N in chitosan with the Co(Ⅱ) in CoSalen complex. Because the site isolation effect present in CS-CoSalen may inhibit the formation of dimers and_ -oxo-dimers of CoSalen, the coordinated CoSalen showed a more efficient activity in the oxidation reaction of ethanethiol than the monomeric complex.
A silica supported catalyst, CoSalen (Co(Ⅱ) complex of bis (salicylideneethylene diamine)) coordinated with chitosan (SiO2-CS-CoSalen), was prepared. The chitosan film coated on the silica surface was characterized through elemental analysis, IR, fluorescence spectrophotometry, ESR and XPS. It is found that the coordination is realized through binding of N in chitosan with the Co(Ⅱ) in CoSalen complex. Because the site isolation effect present in CS-CoSalen may inhibit the formation of dimers and_ -oxo-dimers of CoSalen, the coordinated CoSalen showed a more efficient activity in the oxidation reaction of ethanethiol than the monomeric complex.
2001, 18(4): 295-298
Abstract:
Fe2O3 nano-powders doped with Pd and other elements were prepared by co-precipitation and the doped sensor elements were characterized by XRD, TEM and specific surface area measurements CO sensors were fabricated with the nano-powders. The effects of the kinds and contents of doped elements, calcination temperature on the sensitivity of sensors were examined. The results showed that T-Fe2O3 doped with 5% Sn4+ and 1% Pd2+, calcinated at 450℃ gave the best sensitivity to CO.
Fe2O3 nano-powders doped with Pd and other elements were prepared by co-precipitation and the doped sensor elements were characterized by XRD, TEM and specific surface area measurements CO sensors were fabricated with the nano-powders. The effects of the kinds and contents of doped elements, calcination temperature on the sensitivity of sensors were examined. The results showed that T-Fe2O3 doped with 5% Sn4+ and 1% Pd2+, calcinated at 450℃ gave the best sensitivity to CO.
2001, 18(4): 299-301
Abstract:
The liquid dioxane-NO2 additive was prepared by absorption of NO2 gas into dioxane. The experimental results showed that the additive could convert oximes (13 oxime derivatives were tested.) to corresponding ketones at room temperature for 2~4.5 hours, while the NO2 as an original oxidant was reduced to N2. At molar ratio of oxime to dioxane-NO2=4:1 the maximum yields of hydrazone derivatives as a result of reaction with 2,4-dinitrophenylhydrazine could be obtained. The process provides a pollution-free method for treatment of waste NO2 gas and selective degradation of oximes.
The liquid dioxane-NO2 additive was prepared by absorption of NO2 gas into dioxane. The experimental results showed that the additive could convert oximes (13 oxime derivatives were tested.) to corresponding ketones at room temperature for 2~4.5 hours, while the NO2 as an original oxidant was reduced to N2. At molar ratio of oxime to dioxane-NO2=4:1 the maximum yields of hydrazone derivatives as a result of reaction with 2,4-dinitrophenylhydrazine could be obtained. The process provides a pollution-free method for treatment of waste NO2 gas and selective degradation of oximes.
2001, 18(4): 302-304
Abstract:
The extraction of phenol in water by N-octanoylpyrrolidine (OPOD) in kerosene has been satisfactorily carried out. The dependence of the extraction distribution ratio on the concentrations of extractant, phenol, acidity and temperature was investigated. The composition of the extraction complex was deduced by the slope method to be C6H5OH·OPOD, and the related thermodynamic functions were evaluated. The IR and NMR spectra showed the presence of intermolecular hydrogen bonding between phenol and OPOD in the extraction complexes.
The extraction of phenol in water by N-octanoylpyrrolidine (OPOD) in kerosene has been satisfactorily carried out. The dependence of the extraction distribution ratio on the concentrations of extractant, phenol, acidity and temperature was investigated. The composition of the extraction complex was deduced by the slope method to be C6H5OH·OPOD, and the related thermodynamic functions were evaluated. The IR and NMR spectra showed the presence of intermolecular hydrogen bonding between phenol and OPOD in the extraction complexes.
2001, 18(4): 305-308
Abstract:
The pH-sensitive hydrogel networks comprising of MAA and poloxamer were synthesized by free-radical solution polymerization. The gels exhibit pH-dependant solute diffusivity due to the formation or disruption of hydrogen bondings between MAA and EO unit in poloxamer molecules. The values of diffusion coefficients of dextromethorphan (DMP) and vitamin(Vb12) were found in range from 10-7 to 10-6 cm2/s in uncomplexed hydrogels(pH 7.0) and from 10-11 to 10-8 cm2/s in complexed hydrogels (pH 4.0),respectively. Solute diffusivity decreased as solute size increased. The mole ratio of EO unit to MAA unit is the main factor that affects equilibrium swelling, solute partition and permeability characteristics of these hydrogels.
The pH-sensitive hydrogel networks comprising of MAA and poloxamer were synthesized by free-radical solution polymerization. The gels exhibit pH-dependant solute diffusivity due to the formation or disruption of hydrogen bondings between MAA and EO unit in poloxamer molecules. The values of diffusion coefficients of dextromethorphan (DMP) and vitamin(Vb12) were found in range from 10-7 to 10-6 cm2/s in uncomplexed hydrogels(pH 7.0) and from 10-11 to 10-8 cm2/s in complexed hydrogels (pH 4.0),respectively. Solute diffusivity decreased as solute size increased. The mole ratio of EO unit to MAA unit is the main factor that affects equilibrium swelling, solute partition and permeability characteristics of these hydrogels.
2001, 18(4): 309-311
Abstract:
A novel polymer-supported metallocene catalyst has been prepared. The polymer-supported metallocene displayed considerably high activity in ethylene polymerization,the highest being 3.62×107 g/(mol·h), the molecular weight of the polyethylene produced was Mn=1.29×105, about 3~4 times those prepared by corresponding homogeneous zirconocenes. The polymer supported metallocene [poly(styrene-acrylamide)supported zirconocene] keeps the characteristics of homogeneous metallocene catalysts, and offers some features, such as adaptable to gas phase and slurry processes; easy to prepare in low cost; relatively high activity and lower MAO/Zr ratio; lower inorganic residues in the polyolefins as compared to those using SiO2, Al2O3 or MgCl2; unitary active structure, no complex surface as with SiO2; good control of morphology of the resulting polymer.
A novel polymer-supported metallocene catalyst has been prepared. The polymer-supported metallocene displayed considerably high activity in ethylene polymerization,the highest being 3.62×107 g/(mol·h), the molecular weight of the polyethylene produced was Mn=1.29×105, about 3~4 times those prepared by corresponding homogeneous zirconocenes. The polymer supported metallocene [poly(styrene-acrylamide)supported zirconocene] keeps the characteristics of homogeneous metallocene catalysts, and offers some features, such as adaptable to gas phase and slurry processes; easy to prepare in low cost; relatively high activity and lower MAO/Zr ratio; lower inorganic residues in the polyolefins as compared to those using SiO2, Al2O3 or MgCl2; unitary active structure, no complex surface as with SiO2; good control of morphology of the resulting polymer.
2001, 18(4): 312-314
Abstract:
3-Formylchrone reacted with aroylhydrazine to give corresponding hydrazone, which was treated with acetic anhydride to give a series of chromones with substitution of 1,3,4-dihydrooxadiazoly in 3-position. The chromone formation reaction could be finished in a much short time by microwave irradiation heating.
3-Formylchrone reacted with aroylhydrazine to give corresponding hydrazone, which was treated with acetic anhydride to give a series of chromones with substitution of 1,3,4-dihydrooxadiazoly in 3-position. The chromone formation reaction could be finished in a much short time by microwave irradiation heating.
Synthesis of Double-hydroxyl Tetracoordinate Silicon Directly from Natural SiO2 and Characterization
2001, 18(4): 315-317
Abstract:
A high reactive pentacoordinate organic silicon complex was at first prepared by reaction of natural silica with ethylene glycol and potassium hydroxide. Then a novel tetracoordinate silicon was synthesized by reacting the pentacoordinate silicon with HCl. The product was characterized and analyzed by FTIR, NMR and TG/DTG.
A high reactive pentacoordinate organic silicon complex was at first prepared by reaction of natural silica with ethylene glycol and potassium hydroxide. Then a novel tetracoordinate silicon was synthesized by reacting the pentacoordinate silicon with HCl. The product was characterized and analyzed by FTIR, NMR and TG/DTG.
2001, 18(4): 318-320
Abstract:
Threo-N-benzoyl-3-phenylisoserine methyl ester was synthesized. Compound 3 was first prepared from benzaldehyde and ethyl chloroacetate by Darzens condensation, then through ammonolysis, hydrolysis, acylation and methylation, erythro-N-benzoyl-3-phenylisoserine methyl ester was obtained. The C-2 configuration inversion of the latter compound affords the title compound in yield of 42%. The compound was characterized by IR, 1H NMR and elemental analysis.
Threo-N-benzoyl-3-phenylisoserine methyl ester was synthesized. Compound 3 was first prepared from benzaldehyde and ethyl chloroacetate by Darzens condensation, then through ammonolysis, hydrolysis, acylation and methylation, erythro-N-benzoyl-3-phenylisoserine methyl ester was obtained. The C-2 configuration inversion of the latter compound affords the title compound in yield of 42%. The compound was characterized by IR, 1H NMR and elemental analysis.
2001, 18(4): 321-323
Abstract:
Supported rare earth catalysts were made from Nd(O-i-Pr)3 and the chlorides as well as bromides of the elements of ⅠA and ⅡA groups which were used as supporters of the catalyst. In the study on the relationship between the composition of supporters and the polymerization activity of butadiene in the presence of the supported rare earth catalysts, it was found that the electronegativity of ⅠA or ⅡA elements has an obvious effect on the activity of supported catalysts, that is the activity of the supported catalyst increases with the increasing of the electronegativity. This phenomenon is explained in terms of the interaction between the HOMO of the butadiene and the LUMO of the neodymium. This rule also holds in the case when halides of magnesium were used as supporters.
Supported rare earth catalysts were made from Nd(O-i-Pr)3 and the chlorides as well as bromides of the elements of ⅠA and ⅡA groups which were used as supporters of the catalyst. In the study on the relationship between the composition of supporters and the polymerization activity of butadiene in the presence of the supported rare earth catalysts, it was found that the electronegativity of ⅠA or ⅡA elements has an obvious effect on the activity of supported catalysts, that is the activity of the supported catalyst increases with the increasing of the electronegativity. This phenomenon is explained in terms of the interaction between the HOMO of the butadiene and the LUMO of the neodymium. This rule also holds in the case when halides of magnesium were used as supporters.
2001, 18(4): 324-326
Abstract:
The by-products from the dehydration of exo-2-camphanol in the camphor manufacture by hydration process contains two unknown components:A in 14% and B in 15%. The sample mixture containing 90% A and B with different mass ratio(ca. 1:1, 1:2 and 1:4) were collected by further fine fractional distillation with 60 plate number for spectroscopic characterization. The combined spectral results of GC, MS and 13C NMR of the samples revealed that A is exo-2,2,3-trimethylbicyclo[2,2,1] heptane (exo-isocamphane) and B is endo-2,2,3-trimethylbicyclo [2,2,1] heptane (endo-isocomphane).
The by-products from the dehydration of exo-2-camphanol in the camphor manufacture by hydration process contains two unknown components:A in 14% and B in 15%. The sample mixture containing 90% A and B with different mass ratio(ca. 1:1, 1:2 and 1:4) were collected by further fine fractional distillation with 60 plate number for spectroscopic characterization. The combined spectral results of GC, MS and 13C NMR of the samples revealed that A is exo-2,2,3-trimethylbicyclo[2,2,1] heptane (exo-isocamphane) and B is endo-2,2,3-trimethylbicyclo [2,2,1] heptane (endo-isocomphane).
2001, 18(4): 327-328
Abstract:
Benzyl p-hydroxybenzoate was prepared from benzyl chloride and p-hydroxybenzoic acid by phase transfer catalysis, in which xylene was used as an organic solvent, Na2CO3 aqueous solution as a condensing agent and Bu4NCl as a phase transfer catalyst. The effects of reaction time, Na2CO3 concentration and feed amount of raw materials were investigated. The concentration of Na2CO3 aqueous solution was the most important factor. Prodact with purity greater 98% and yield more 85% was obtained.
Benzyl p-hydroxybenzoate was prepared from benzyl chloride and p-hydroxybenzoic acid by phase transfer catalysis, in which xylene was used as an organic solvent, Na2CO3 aqueous solution as a condensing agent and Bu4NCl as a phase transfer catalyst. The effects of reaction time, Na2CO3 concentration and feed amount of raw materials were investigated. The concentration of Na2CO3 aqueous solution was the most important factor. Prodact with purity greater 98% and yield more 85% was obtained.
2001, 18(4): 329-331
Abstract:
The chromatographic behavior of twenty three amino acids on the silica gel thin layers using sodium dodecylsulfate (SDS)/n butyl alcohol/n hexane/water microemulsion as a developer have been studied. The results showed that the W/O microemulsion and the bicontinuous microemulsion composed of the mentioned components appeared suitable developers for TLC analysis of amino acids.
The chromatographic behavior of twenty three amino acids on the silica gel thin layers using sodium dodecylsulfate (SDS)/n butyl alcohol/n hexane/water microemulsion as a developer have been studied. The results showed that the W/O microemulsion and the bicontinuous microemulsion composed of the mentioned components appeared suitable developers for TLC analysis of amino acids.
2001, 18(4): 332-334
Abstract:
The thermogravimetric analysis of ENR (epoxidized natural rubber) has been carried out by TG DTG methods at temperature rising rate of 5, 10, 15 and 20℃·min-1. The results showed that the activation energy of the thermoreaction in flowing air during the course of mass loss wasn't always keep rising, but declined at mass loss of 1.0%~10.0%, 20.0%~30.0% and 70.0%~80.0%.
The thermogravimetric analysis of ENR (epoxidized natural rubber) has been carried out by TG DTG methods at temperature rising rate of 5, 10, 15 and 20℃·min-1. The results showed that the activation energy of the thermoreaction in flowing air during the course of mass loss wasn't always keep rising, but declined at mass loss of 1.0%~10.0%, 20.0%~30.0% and 70.0%~80.0%.
2001, 18(4): 335-337
Abstract:
Tow nanosize powders of β-Ni(OH)2 and NiO were synthesized by solid state reaction of NiC2O4·2H2O with NaOH and NiCl2·6H2O with NaOH respectively and characterized by XRD and SEM. Their electrochemical properties were investigated. The results shown that the composite electrode materials composed of the two kinds of nano particles and zinc powder displayed excellent discharge property.
Tow nanosize powders of β-Ni(OH)2 and NiO were synthesized by solid state reaction of NiC2O4·2H2O with NaOH and NiCl2·6H2O with NaOH respectively and characterized by XRD and SEM. Their electrochemical properties were investigated. The results shown that the composite electrode materials composed of the two kinds of nano particles and zinc powder displayed excellent discharge property.
2001, 18(4): 338-339
Abstract:
The Ginkgo flavones were extracted from water leaching liquor of the Ginkgo leaves. The leaching conditions, extractant, extraction time, temperature, pH of the extraction solution and phase separation have been investigated. The optimum extraction conditions are:60℃, 30 min. pH=3~4 and with ethylbutyl ketone as extractant.
The Ginkgo flavones were extracted from water leaching liquor of the Ginkgo leaves. The leaching conditions, extractant, extraction time, temperature, pH of the extraction solution and phase separation have been investigated. The optimum extraction conditions are:60℃, 30 min. pH=3~4 and with ethylbutyl ketone as extractant.
2001, 18(4): 340-341
Abstract:
Soluble aromatic hyperbranched polyesters with controlled viscosities have been prepared by melt polycondensation of sililated 5-acetoxyisophathalic acid with sililated p-tert-butyl benzoic acid in various molar ratios. By further reaction with thionyl chloride and propargyl alcohol successively, the endgroups of the crude polyester were transferred into ethynylic groups in 78.2% yield as calculated by 1H NMR spectra.
Soluble aromatic hyperbranched polyesters with controlled viscosities have been prepared by melt polycondensation of sililated 5-acetoxyisophathalic acid with sililated p-tert-butyl benzoic acid in various molar ratios. By further reaction with thionyl chloride and propargyl alcohol successively, the endgroups of the crude polyester were transferred into ethynylic groups in 78.2% yield as calculated by 1H NMR spectra.
2001, 18(4): 342-344
Abstract:
The Belousov-Zhabotinskii type oscillation has been studied in sucrose-BrO3--Mn2+-H+-acetone system. Individual oscillations of low frequency and high frequency were observed and discussed.
The Belousov-Zhabotinskii type oscillation has been studied in sucrose-BrO3--Mn2+-H+-acetone system. Individual oscillations of low frequency and high frequency were observed and discussed.
