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2005 Volume 22 Issue 2
2005, 22(2): 117-122
Abstract:
With home-made Ni0.5Mg0.5O as the catalyst, canbon nanotubes(CNTs) were synthesized from the catalytic pyrolysis of methane in a Φ 32 mm fluidized-bed reactor. The operation conditions for the transition of fixed catalyst-bed and fluidized catalyst-bed and their influence on the growth of CNTs were investigated. The optimized conditions in the Φ 32 mm fluidized-bed reactor are as follows, i.e., the temperature of reactor is ca. 853 K, the linear velocity of feed-gas CH4 18~22 cm/s and the GHSV of CH4 3×104~6×104 mL(STP)/(h·g)-catal. The maximum yield of reaction for 1 h is 10 g-CNTs/g-catal. The obtained CNT products were confirmed by means of TEM, SEM, TPH, XRD and LRS to be multi-walled carbon nanotubes(MWCNTs) with an outer diameter of 10~50 nm, and the contents of carbon and graphitic-carbon in the purified CNT products were found to be ≥99.5% and ≥90%, respectively.
With home-made Ni0.5Mg0.5O as the catalyst, canbon nanotubes(CNTs) were synthesized from the catalytic pyrolysis of methane in a Φ 32 mm fluidized-bed reactor. The operation conditions for the transition of fixed catalyst-bed and fluidized catalyst-bed and their influence on the growth of CNTs were investigated. The optimized conditions in the Φ 32 mm fluidized-bed reactor are as follows, i.e., the temperature of reactor is ca. 853 K, the linear velocity of feed-gas CH4 18~22 cm/s and the GHSV of CH4 3×104~6×104 mL(STP)/(h·g)-catal. The maximum yield of reaction for 1 h is 10 g-CNTs/g-catal. The obtained CNT products were confirmed by means of TEM, SEM, TPH, XRD and LRS to be multi-walled carbon nanotubes(MWCNTs) with an outer diameter of 10~50 nm, and the contents of carbon and graphitic-carbon in the purified CNT products were found to be ≥99.5% and ≥90%, respectively.
2005, 22(2): 123-127
Abstract:
A new universal dye containing two naphthalene rings was prepared by condensation of 7-aceta-mide-4-hydroxy-2-naphthalene sulfonyl chloride with N,N-dimethylethylenediamine, followed by the coupling reaction with ammonium of m-amino-benzene-β-hydroxyethylene sulfonate. The chemical structures of the new dye and the intermediate were confirmed by Mass Spectrometry, 1H NMR and 13C NMR analyses. By adjusting the pH value of the dyebath and adding textile auxiliaries, the synthesized universal dye was applied to dye cotton, wool, silk, nylon, acrylic and PET fabrics without conducting other chemical reactions outside the dyebath. The exhaustion rates of dye on the fabrics aforementioned were 6.2%, 59.8%, 44.7%, 33.5%, 11.1% and 9.2%, respectively, which reveals that the dye has good affinity for wool, silk and nylon fabrics. The washfastness grades of dyed wool, silk and nylon fabrics were all higher than 3, while their lightfastness properties were not satisfactory.
A new universal dye containing two naphthalene rings was prepared by condensation of 7-aceta-mide-4-hydroxy-2-naphthalene sulfonyl chloride with N,N-dimethylethylenediamine, followed by the coupling reaction with ammonium of m-amino-benzene-β-hydroxyethylene sulfonate. The chemical structures of the new dye and the intermediate were confirmed by Mass Spectrometry, 1H NMR and 13C NMR analyses. By adjusting the pH value of the dyebath and adding textile auxiliaries, the synthesized universal dye was applied to dye cotton, wool, silk, nylon, acrylic and PET fabrics without conducting other chemical reactions outside the dyebath. The exhaustion rates of dye on the fabrics aforementioned were 6.2%, 59.8%, 44.7%, 33.5%, 11.1% and 9.2%, respectively, which reveals that the dye has good affinity for wool, silk and nylon fabrics. The washfastness grades of dyed wool, silk and nylon fabrics were all higher than 3, while their lightfastness properties were not satisfactory.
2005, 22(2): 128-131
Abstract:
Removal of SO2 in simulated flue gas was investigated via strong ionization discharge. Hydroxyl radicals with high-concentration were produced by means of the ionization of O2 and H2O molecules, which oxidized SO2 directly into H2SO4 droplets at 120℃ in the absence of any catalyst and absorbent. H2SO4 were collected with the electrostatic precipitator. As a result, the removal efficiency of SO2 is 84.0%. The removal efficiency of SO2 increases with the increases of the concentrations of O2 and H2O, the reaction time and the intensity of electric field of discharging, and decreases with the increases of SO2 concentration and flow rate of flue gas. The reaction time is only 0.8 s.
Removal of SO2 in simulated flue gas was investigated via strong ionization discharge. Hydroxyl radicals with high-concentration were produced by means of the ionization of O2 and H2O molecules, which oxidized SO2 directly into H2SO4 droplets at 120℃ in the absence of any catalyst and absorbent. H2SO4 were collected with the electrostatic precipitator. As a result, the removal efficiency of SO2 is 84.0%. The removal efficiency of SO2 increases with the increases of the concentrations of O2 and H2O, the reaction time and the intensity of electric field of discharging, and decreases with the increases of SO2 concentration and flow rate of flue gas. The reaction time is only 0.8 s.
2005, 22(2): 132-137
Abstract:
Ag was deposited by H2 reduction on the surface of TiO2 nanoparticles. The results of SEM, XRD and UV-vis show that Ag distributes uniformly on the TiO2 surface and the Einstein shift can be observed clearly in the UV-vis adsorption spectrum. UV and sunlight were used as light sources to investigate the photocatalytic activity of the Ag/TiO2 composite catalyst for the degradation of methyl orange. The results show that the optimized amount of deposited Ag is 0.25%(molar ratio of Ag to TiO2) and the calcination temperature influences slightly the photocatalytic activity when it is lower than 300℃. For the UV light degradation reation, the optimum photocatalyst concentration was determined to be 1.25 g/L. Both weakly acidic condition and the presence of peroxide are of great advantage to the light degradation reaction. The photocatalytic activity increases with the decrease of the total volume of the solution or the increase of the illumination intensity in unit volume. The degradation of methyl orange follows first-order reaction kinetics for different catalysts. Compared with pure TiO2, Ag/TiO2 shows higher photocatalytic activity when it is used to degrade methyl orange under sunlight.
Ag was deposited by H2 reduction on the surface of TiO2 nanoparticles. The results of SEM, XRD and UV-vis show that Ag distributes uniformly on the TiO2 surface and the Einstein shift can be observed clearly in the UV-vis adsorption spectrum. UV and sunlight were used as light sources to investigate the photocatalytic activity of the Ag/TiO2 composite catalyst for the degradation of methyl orange. The results show that the optimized amount of deposited Ag is 0.25%(molar ratio of Ag to TiO2) and the calcination temperature influences slightly the photocatalytic activity when it is lower than 300℃. For the UV light degradation reation, the optimum photocatalyst concentration was determined to be 1.25 g/L. Both weakly acidic condition and the presence of peroxide are of great advantage to the light degradation reaction. The photocatalytic activity increases with the decrease of the total volume of the solution or the increase of the illumination intensity in unit volume. The degradation of methyl orange follows first-order reaction kinetics for different catalysts. Compared with pure TiO2, Ag/TiO2 shows higher photocatalytic activity when it is used to degrade methyl orange under sunlight.
2005, 22(2): 138-141
Abstract:
CuSCN thin films were prepared by the electrodeposition method from an EDTA-chelated Cu(Ⅱ) and KSCN aqueous solution. The instability of Cu(SCN)2 in water and function of EDTA complexant on improving the stability of CuSO4 and KSCN solution were studied. The results show that Cu(SCN)2 can transform into CuSCN and (SCN)x in the absence of EDTA; a stable aqueous electrolyte is obtained in the presence of EDTA. Transparent CuSCN thin film is prepared in an aqueous electrolyte when the molar ratio of Cu2+ to EDTA is 1:1 and Cu2+ to SCN- 4:1. The average crystal size of CuSCN thin film is 50 nm, band gap ~3.8 eV and conductivity up to 0.8×10-3 S/cm.
CuSCN thin films were prepared by the electrodeposition method from an EDTA-chelated Cu(Ⅱ) and KSCN aqueous solution. The instability of Cu(SCN)2 in water and function of EDTA complexant on improving the stability of CuSO4 and KSCN solution were studied. The results show that Cu(SCN)2 can transform into CuSCN and (SCN)x in the absence of EDTA; a stable aqueous electrolyte is obtained in the presence of EDTA. Transparent CuSCN thin film is prepared in an aqueous electrolyte when the molar ratio of Cu2+ to EDTA is 1:1 and Cu2+ to SCN- 4:1. The average crystal size of CuSCN thin film is 50 nm, band gap ~3.8 eV and conductivity up to 0.8×10-3 S/cm.
2005, 22(2): 142-147
Abstract:
Five amino-acid Schiff bases and their corresponding Cu(Ⅱ) complexes as well as D-glucosamine Schiff bases and their corresponding V(Ⅳ) complexes were synthesized and characterized by means of elemental analysis, infrared absorption spectra, 1H NMR and TG. The catalytic activities of the complexes in the enantioselective oxidative couplings of β-napthol to BINOL were studied. The best result of yield and e.e. value are 81.7% and 28.4% for the Cu catalyst and 87.5% and 60.3% for the V catalyst. Experimental results show that the optical activity of the product was affected greatly by the coordination structure of the center ions.
Five amino-acid Schiff bases and their corresponding Cu(Ⅱ) complexes as well as D-glucosamine Schiff bases and their corresponding V(Ⅳ) complexes were synthesized and characterized by means of elemental analysis, infrared absorption spectra, 1H NMR and TG. The catalytic activities of the complexes in the enantioselective oxidative couplings of β-napthol to BINOL were studied. The best result of yield and e.e. value are 81.7% and 28.4% for the Cu catalyst and 87.5% and 60.3% for the V catalyst. Experimental results show that the optical activity of the product was affected greatly by the coordination structure of the center ions.
2005, 22(2): 148-151
Abstract:
A polysiloxane microemulsion was prepared by the cationic ring-opening polymerization of octamethylcyclotetrasiloxane(D4) in an oil-in-water microemulsion medium with dodecylbenzenesulfonic acid as the catalyst. The nucleation mechanism of the formation of polymer latex in the microemulsion medium was investigated. The results show that many new polymer particles were produced in the course of polymerization, which were much smaller than monomer droplets in size. The system underwent bimodal particle size distribution, which corresponded to smaller polymer particles and initial monomer droplets respectively. After equilibrium conversions were reached, the polysiloxane microemulsion with single peak distribution and smaller particle size than that of initial monomer droplets was formed. It suggests that the nucleation took place in the aqueous phase, not in D4 droplets by the oligomers with end-hydroxyl groups produced as a result of D4 ring-opening polymerization. The mechanism is similar to the homogeneous nucleation in radical emulsion polymerization. The polymerization temperature affected the particle size distribution, while its effect on the mean particle size was insignificant. Narrower particle size distribution of microemulsions was found when the polymerization was carried out at 80℃. The equilibrium molecular weight of the polymer was lower than that of the polymer from conventional emulsion system at the same polymerization temperature, and the effect of temperature on the molecular weight was little. The mass ratio of emulsifier to coemulsifier affected the size of D4 droplets and subsequently the latex particle size of the polymer microemulsion.
A polysiloxane microemulsion was prepared by the cationic ring-opening polymerization of octamethylcyclotetrasiloxane(D4) in an oil-in-water microemulsion medium with dodecylbenzenesulfonic acid as the catalyst. The nucleation mechanism of the formation of polymer latex in the microemulsion medium was investigated. The results show that many new polymer particles were produced in the course of polymerization, which were much smaller than monomer droplets in size. The system underwent bimodal particle size distribution, which corresponded to smaller polymer particles and initial monomer droplets respectively. After equilibrium conversions were reached, the polysiloxane microemulsion with single peak distribution and smaller particle size than that of initial monomer droplets was formed. It suggests that the nucleation took place in the aqueous phase, not in D4 droplets by the oligomers with end-hydroxyl groups produced as a result of D4 ring-opening polymerization. The mechanism is similar to the homogeneous nucleation in radical emulsion polymerization. The polymerization temperature affected the particle size distribution, while its effect on the mean particle size was insignificant. Narrower particle size distribution of microemulsions was found when the polymerization was carried out at 80℃. The equilibrium molecular weight of the polymer was lower than that of the polymer from conventional emulsion system at the same polymerization temperature, and the effect of temperature on the molecular weight was little. The mass ratio of emulsifier to coemulsifier affected the size of D4 droplets and subsequently the latex particle size of the polymer microemulsion.
2005, 22(2): 152-157
Abstract:
Glutaldelyde-crosslinked silkworn chitosan-glutamic acid cation exchange resin was prepared, and its exchange capacity for each of L-lysine, L-citrulline and Zn2+ has been examined. The optimum conditions for the exhange resin preparation are that the mass ratio of chitosan to glutamic acid is 1:0.75, reaction time is 4 h, temperature is at 30℃. The resin is nearly a porous round granula with stacking density of 0.413 g/mL, mass loss ratio 0.66%, water content 85.79% and swelling degree 72.73%. The dynamic exchange capacities of the resin for lysine, citrulline and Zn2+ are 188, 191 and 421.5 mg/g, based on dry resin, respec-tively.
Glutaldelyde-crosslinked silkworn chitosan-glutamic acid cation exchange resin was prepared, and its exchange capacity for each of L-lysine, L-citrulline and Zn2+ has been examined. The optimum conditions for the exhange resin preparation are that the mass ratio of chitosan to glutamic acid is 1:0.75, reaction time is 4 h, temperature is at 30℃. The resin is nearly a porous round granula with stacking density of 0.413 g/mL, mass loss ratio 0.66%, water content 85.79% and swelling degree 72.73%. The dynamic exchange capacities of the resin for lysine, citrulline and Zn2+ are 188, 191 and 421.5 mg/g, based on dry resin, respec-tively.
2005, 22(2): 158-163
Abstract:
Soft package lithium-ion batteries with graphite as anode and LiCoO2 as cathode were prepared. The liquid electrolytes were composed of 1 mol/L LiPF6 in various mixed solvents(by mass ratio):(ethylene carbonate(EC))/(dimethyl carbonate(DMC))/(γ-butyrolactone(GBL))(4:4:3)+4%(mass fraction) vinylene carbonate(VC), EC/DMC(1:1), EC/GBL(4:3) and EC/DMC/GBL(4:4:3). The electro-chemical behavior of each of the electrolytes was examined by measurements of vapor pressure, low temperature conductivity, oxidation potential, cycling performance and thickness change of soft package lithium-ion batteries during storage at 348 K or cycling at 298 K. The results exhibited excellent electrochemical behavior when the electrolyte consisted of 1 mol/L LiPF6 EC/DMC/GBL(mass ratio 4:4:3)+4%(mass fraction)VC. Two oxidation potential shoulders were recorded on the linear sweep voltage curve, one shoulder was at 2.95 V vs Li/Li+ for VC and the other shoulder was at 4.62 V vs Li/Li+ for other mixed solvents. An SEI film with a very low impedance was formed. The soft package lithium-ion battery with the liquid electrolyte had a thickness of ca. 3.0 mm, with an energy density of 165 W·h/kg, capacity ratio of 89% after 200 cycles at 1 C rate and 298 K, 60% at 0.5 C rate and 255 K. The increment of thickness was less than 0.1 mm after being stored at 348 K and 4.2 V for 24 h.
Soft package lithium-ion batteries with graphite as anode and LiCoO2 as cathode were prepared. The liquid electrolytes were composed of 1 mol/L LiPF6 in various mixed solvents(by mass ratio):(ethylene carbonate(EC))/(dimethyl carbonate(DMC))/(γ-butyrolactone(GBL))(4:4:3)+4%(mass fraction) vinylene carbonate(VC), EC/DMC(1:1), EC/GBL(4:3) and EC/DMC/GBL(4:4:3). The electro-chemical behavior of each of the electrolytes was examined by measurements of vapor pressure, low temperature conductivity, oxidation potential, cycling performance and thickness change of soft package lithium-ion batteries during storage at 348 K or cycling at 298 K. The results exhibited excellent electrochemical behavior when the electrolyte consisted of 1 mol/L LiPF6 EC/DMC/GBL(mass ratio 4:4:3)+4%(mass fraction)VC. Two oxidation potential shoulders were recorded on the linear sweep voltage curve, one shoulder was at 2.95 V vs Li/Li+ for VC and the other shoulder was at 4.62 V vs Li/Li+ for other mixed solvents. An SEI film with a very low impedance was formed. The soft package lithium-ion battery with the liquid electrolyte had a thickness of ca. 3.0 mm, with an energy density of 165 W·h/kg, capacity ratio of 89% after 200 cycles at 1 C rate and 298 K, 60% at 0.5 C rate and 255 K. The increment of thickness was less than 0.1 mm after being stored at 348 K and 4.2 V for 24 h.
2005, 22(2): 164-167
Abstract:
The films of linear-low density polyethylenes made with metallocene catalyst and Ziegler-Natta catalyst respectively and low density polyethylene, were irradiated with a Xenon lamp for various time to examine their photo-oxidation stability. The mechanical property and chemical structure changes occurred during the photo-oxidation process were studied by mechanical property measurement and FTIR spectroscopy. The results show that both the branching degree and crystallinity of polyethylenes increase after photo-oxidization. The concentration of vinylidene decreases gradually with the prolongation of irradiation time, while that of end-vinyl increases due to NorrishⅡ reaction. Ethylene-hexene copolymerized m-LLDPE is more inclined to be photo-oxidized than ethylene-octene copolymerized LLDPE due to the higher concentration of vinylidene in the former. The photo-oxidation stability of the other two ethylene-octene copolymerized m-LLDPEs is comparable to that of LLDPE with the same comonomers. The oxidation rate of LDPE studied in the paper is slower than those of all the LLDPEs.
The films of linear-low density polyethylenes made with metallocene catalyst and Ziegler-Natta catalyst respectively and low density polyethylene, were irradiated with a Xenon lamp for various time to examine their photo-oxidation stability. The mechanical property and chemical structure changes occurred during the photo-oxidation process were studied by mechanical property measurement and FTIR spectroscopy. The results show that both the branching degree and crystallinity of polyethylenes increase after photo-oxidization. The concentration of vinylidene decreases gradually with the prolongation of irradiation time, while that of end-vinyl increases due to NorrishⅡ reaction. Ethylene-hexene copolymerized m-LLDPE is more inclined to be photo-oxidized than ethylene-octene copolymerized LLDPE due to the higher concentration of vinylidene in the former. The photo-oxidation stability of the other two ethylene-octene copolymerized m-LLDPEs is comparable to that of LLDPE with the same comonomers. The oxidation rate of LDPE studied in the paper is slower than those of all the LLDPEs.
2005, 22(2): 168-171
Abstract:
A silver nanoparticle/L-cysteine modified gold electrode was prepared and its electrochemical behaviour was evaluated by means of electrochemical impedance spectrocscopy(EIS) and cyclic voltammetry(CV). The surface coverage of Ag on the modified electrode((5.7±0.4)×10-10 mol/cm2) was calculated based on the linear relationship between peak current and scan rate. The modified electrode accelerates the response of redox of hydroquinone stably. The oxidation peak current is linearly changed with the concentration of hydroquinone at the modified electrode in the concentration range of 3.0×10-3 to 2.0 mmol/L. The linear regression equation is ip(μA)=-0.056+1.137c(μmol/L), with correlation coefficient λ=0.998 1, detection limit=0.172 μmol/L, signal-to-noise ratio=3.
A silver nanoparticle/L-cysteine modified gold electrode was prepared and its electrochemical behaviour was evaluated by means of electrochemical impedance spectrocscopy(EIS) and cyclic voltammetry(CV). The surface coverage of Ag on the modified electrode((5.7±0.4)×10-10 mol/cm2) was calculated based on the linear relationship between peak current and scan rate. The modified electrode accelerates the response of redox of hydroquinone stably. The oxidation peak current is linearly changed with the concentration of hydroquinone at the modified electrode in the concentration range of 3.0×10-3 to 2.0 mmol/L. The linear regression equation is ip(μA)=-0.056+1.137c(μmol/L), with correlation coefficient λ=0.998 1, detection limit=0.172 μmol/L, signal-to-noise ratio=3.
2005, 22(2): 172-175
Abstract:
o-Aminobenzenethiol(ABT) is covalently combined onto a bare gold electrode to form a self-assembled monolayers modified electrode(ABT/Au SAMs). Attenuated total reflection-Fourier transform infrared spectroscopy was used for the characterization of the films. The modified electrode has an excellent electrocatalytic activity for the oxidation and reduction of dopamine(DP). At ABT/Au SAMs, the oxidation peak potential of dopamine Epa shifts negatively and the reduction peak potential Epc shifts positively compared with those at the bare gold electrode. The diffusion coefficient of dopamine on the modified electrode is 3.19×10-6 cm2/s. The electrocatalytic mechanism is discussed. The reduction peak current increases with the increase in the concentration of dopamine. The reduction peak current exhibits a linear relation in the range of 1.0×10-6~8.0×10-4 mol/L. The correlation coefficient is 0.998 2. The detection limit is 2.0×10-7 mol/L.
o-Aminobenzenethiol(ABT) is covalently combined onto a bare gold electrode to form a self-assembled monolayers modified electrode(ABT/Au SAMs). Attenuated total reflection-Fourier transform infrared spectroscopy was used for the characterization of the films. The modified electrode has an excellent electrocatalytic activity for the oxidation and reduction of dopamine(DP). At ABT/Au SAMs, the oxidation peak potential of dopamine Epa shifts negatively and the reduction peak potential Epc shifts positively compared with those at the bare gold electrode. The diffusion coefficient of dopamine on the modified electrode is 3.19×10-6 cm2/s. The electrocatalytic mechanism is discussed. The reduction peak current increases with the increase in the concentration of dopamine. The reduction peak current exhibits a linear relation in the range of 1.0×10-6~8.0×10-4 mol/L. The correlation coefficient is 0.998 2. The detection limit is 2.0×10-7 mol/L.
2005, 22(2): 176-179
Abstract:
Bisphenol A epoxy resin was modified by trimethylchlorosilane(TMS), dimethyldichlorosilane(DMS), or the mixture of DMS and α,ω-dichloro-polydimethylsiloxane(DPS). The influences of modification method and the composition and content of organic silicon on the properties of the material were investigated via the measurements of impact strength, tensile strength, elongation and glass transition tempereture(Tg). The results show that the impact strength of epoxy resin modified with 5.7 g of DMS is 20.2 kJ/m2, tensile strength 67.04 MPa, elongation 11.29% and Tg 167.98℃, more than that of pure epoxy resin by 9.4 kJ/m2, 21.1 MPa, 5.35% and 32.56℃, respectively. The epoxy resin modified with a mixture of 0.7 g of DMS and 10 g of DPS has the impact strength of 31.6 kJ/m2 and elongation of 81.68%, respectively, higher than that of pure resin by 20.8 kJ/m2 and 75.64%, while its Tg and tensile strength seems to have little improvement.
Bisphenol A epoxy resin was modified by trimethylchlorosilane(TMS), dimethyldichlorosilane(DMS), or the mixture of DMS and α,ω-dichloro-polydimethylsiloxane(DPS). The influences of modification method and the composition and content of organic silicon on the properties of the material were investigated via the measurements of impact strength, tensile strength, elongation and glass transition tempereture(Tg). The results show that the impact strength of epoxy resin modified with 5.7 g of DMS is 20.2 kJ/m2, tensile strength 67.04 MPa, elongation 11.29% and Tg 167.98℃, more than that of pure epoxy resin by 9.4 kJ/m2, 21.1 MPa, 5.35% and 32.56℃, respectively. The epoxy resin modified with a mixture of 0.7 g of DMS and 10 g of DPS has the impact strength of 31.6 kJ/m2 and elongation of 81.68%, respectively, higher than that of pure resin by 20.8 kJ/m2 and 75.64%, while its Tg and tensile strength seems to have little improvement.
2005, 22(2): 180-183
Abstract:
A preferential 1,2 elimination reaction of syn diethyl (2-acetylamino-1-bromo-2-(p-methoxy-phenyl)ethyl)phosphonate 1 rather than the anticipated nucleophilic substitution reaction under basic conditions is described in the present paper. The product was characterized by IR, HRMS and NMR spectra. The relatively low ability of the α bromine as a leaving group compared to that of the mesylate group reported in the literature should be attributed to the low degree of conversion when K2CO3 was used. And when 1,8-diazabicyclo-undec-7-ene(DBU) was used, the more sensitivity towards the base of the β proton caused by the induction effect from the higher electronegative α bromine atom should account for the elimination reaction. Without the base, the failure of the displacement of the bromine atom by benzotriazole should be due to the poor leaving ability of bromine as well as the steric hindrance from the bulky phosphonate group.
A preferential 1,2 elimination reaction of syn diethyl (2-acetylamino-1-bromo-2-(p-methoxy-phenyl)ethyl)phosphonate 1 rather than the anticipated nucleophilic substitution reaction under basic conditions is described in the present paper. The product was characterized by IR, HRMS and NMR spectra. The relatively low ability of the α bromine as a leaving group compared to that of the mesylate group reported in the literature should be attributed to the low degree of conversion when K2CO3 was used. And when 1,8-diazabicyclo-undec-7-ene(DBU) was used, the more sensitivity towards the base of the β proton caused by the induction effect from the higher electronegative α bromine atom should account for the elimination reaction. Without the base, the failure of the displacement of the bromine atom by benzotriazole should be due to the poor leaving ability of bromine as well as the steric hindrance from the bulky phosphonate group.
2005, 22(2): 184-187
Abstract:
Polymethylsiloxane/polyacrylate copolymer emulsion was synthesized by a drop-adding monomer emulsion method. The TEM photos demonstrate the core-shell structure of latex particles. The FTIR, 1H NMR and DSC results indicate that hydrogen-containing polymethylsiloxane reacted with acrylate monomer to lead to chemical bond formation, and no hydrolysis occurred. With this copolymer emulsion as a coating agent for cotton fabric, the fabric is not sticky under 60℃ and has no crack under -10℃. When it is used as a calico-printing adhesive for decorative fabric, the fastness of the fabric under dry and wet friction is in grade of 5 and 4, respectively, and no change in color difference was found in the under-cloth which also did not turn to yellow when sublimation fastness was measured at 200℃.
Polymethylsiloxane/polyacrylate copolymer emulsion was synthesized by a drop-adding monomer emulsion method. The TEM photos demonstrate the core-shell structure of latex particles. The FTIR, 1H NMR and DSC results indicate that hydrogen-containing polymethylsiloxane reacted with acrylate monomer to lead to chemical bond formation, and no hydrolysis occurred. With this copolymer emulsion as a coating agent for cotton fabric, the fabric is not sticky under 60℃ and has no crack under -10℃. When it is used as a calico-printing adhesive for decorative fabric, the fastness of the fabric under dry and wet friction is in grade of 5 and 4, respectively, and no change in color difference was found in the under-cloth which also did not turn to yellow when sublimation fastness was measured at 200℃.
2005, 22(2): 188-194
Abstract:
The soap-free emulsion copolymerization of perfluoroalkyl acrylate(FA), methyl methacrylate(MMA) and n-butyl acrylate(n-BA) was carried out in the presence of sodium 2-acrylamide-2-methyl propanesulfonate(AMPSNa) as an ionic comonomer and potassium persulfate(KPS) as the initiator. The effects of reaction temperature and the concentrations of AMPSNa, KPS and FA on the kinetics of copolymerization, particle size and dispersive index(PDI), particle number per micro liter water(Np) were investigated, the electrolyte stability and centrifugation stability of the emulsions were characterized as well. The aqueous dynamic contact angle and water resistance of FA copolymers were determined. The results show that the diameter of latex particles decreases initially and then increases with increase of AMPSNa and KPS concentrations. The polymerization rate indicates the same trend, while the particle diameter increases gradually with increasing fluorinated monomer amount and temperature. Compared with the copolymers prepared by conventional emulsion polymerization, the aqueous dynamic contact angle as well as water resistance of these copolymers were greatly improved.
The soap-free emulsion copolymerization of perfluoroalkyl acrylate(FA), methyl methacrylate(MMA) and n-butyl acrylate(n-BA) was carried out in the presence of sodium 2-acrylamide-2-methyl propanesulfonate(AMPSNa) as an ionic comonomer and potassium persulfate(KPS) as the initiator. The effects of reaction temperature and the concentrations of AMPSNa, KPS and FA on the kinetics of copolymerization, particle size and dispersive index(PDI), particle number per micro liter water(Np) were investigated, the electrolyte stability and centrifugation stability of the emulsions were characterized as well. The aqueous dynamic contact angle and water resistance of FA copolymers were determined. The results show that the diameter of latex particles decreases initially and then increases with increase of AMPSNa and KPS concentrations. The polymerization rate indicates the same trend, while the particle diameter increases gradually with increasing fluorinated monomer amount and temperature. Compared with the copolymers prepared by conventional emulsion polymerization, the aqueous dynamic contact angle as well as water resistance of these copolymers were greatly improved.
2005, 22(2): 195-199
Abstract:
The adsorption of Cu2+, Ni2+ and Co2+ onto chitosan crosslinked by formaldchyde and epichlorohydrin (AECTS) has been studied. The adsorption capacities of AECTS towards Cu2+, Ni2+ and Co2+ were found to be 2.42, 1.37 and 0.39 mmol/g, respectively. The FTIR analysis indicates that the adsorption was realized via the coordination of -NH2 and -OH groups in AECTS to the metal ions, and the binding strength was positively proportional to the adsorption capacity. WAXD results indicate metal ions adsorbed onto both the amorphous and crystal regions of AECTS, and the destructive degree of the crystal region was in direct proportion to the adsorption capacity. TG analysis shows that the crosslinking and metal ions adsorption could change the three decomposition temperatures of CTS to lower degree, depending on adsorption capacity change.
The adsorption of Cu2+, Ni2+ and Co2+ onto chitosan crosslinked by formaldchyde and epichlorohydrin (AECTS) has been studied. The adsorption capacities of AECTS towards Cu2+, Ni2+ and Co2+ were found to be 2.42, 1.37 and 0.39 mmol/g, respectively. The FTIR analysis indicates that the adsorption was realized via the coordination of -NH2 and -OH groups in AECTS to the metal ions, and the binding strength was positively proportional to the adsorption capacity. WAXD results indicate metal ions adsorbed onto both the amorphous and crystal regions of AECTS, and the destructive degree of the crystal region was in direct proportion to the adsorption capacity. TG analysis shows that the crosslinking and metal ions adsorption could change the three decomposition temperatures of CTS to lower degree, depending on adsorption capacity change.
2005, 22(2): 200-203
Abstract:
Magnesium ethoxide complex Mg(OEt)2-x(acac)x was synthesized by means of the electrochemical method. Its ethanol solution was hydrolyzed to give nano-sized xerogel Mg(OEt)2-x-y(OH)y(acac)x. The latter was then heated at 500℃ for 2 h to give nano-sized MgO powder. The precursor, xerogel and MgO powder were characterized by FT-IR, TG-DTA, XRD and TEM. The precursor and xerogel contain acac- group. The latter should be calcinated beween 470~500℃. The MgO powder is of mono disperse structure with the size of 15~20 nm.
Magnesium ethoxide complex Mg(OEt)2-x(acac)x was synthesized by means of the electrochemical method. Its ethanol solution was hydrolyzed to give nano-sized xerogel Mg(OEt)2-x-y(OH)y(acac)x. The latter was then heated at 500℃ for 2 h to give nano-sized MgO powder. The precursor, xerogel and MgO powder were characterized by FT-IR, TG-DTA, XRD and TEM. The precursor and xerogel contain acac- group. The latter should be calcinated beween 470~500℃. The MgO powder is of mono disperse structure with the size of 15~20 nm.
2005, 22(2): 204-206
Abstract:
An amphiphilic ferrocene derivative 3-ferrocenyl-2-butylene acid(FCA) was synthesized. The mixed FCA/octadecylamine(ODA) monolayers on aqueous subphase were studied by means of surface pressure-molecule area(π-A) isotherm, dπ/dA-A curve and the plot of the apparent area of ODA vs x(ODA). The results indicate that the FCA itself did not form monolayer, but the mixed FCA/ODA mono-layers were stable when the mole fraction of ODA was more than 25%, the mixed monolayers possessed the best stability and the highest incompressibility when the mole ratio of FCA to ODA is 1 to 1.
An amphiphilic ferrocene derivative 3-ferrocenyl-2-butylene acid(FCA) was synthesized. The mixed FCA/octadecylamine(ODA) monolayers on aqueous subphase were studied by means of surface pressure-molecule area(π-A) isotherm, dπ/dA-A curve and the plot of the apparent area of ODA vs x(ODA). The results indicate that the FCA itself did not form monolayer, but the mixed FCA/ODA mono-layers were stable when the mole fraction of ODA was more than 25%, the mixed monolayers possessed the best stability and the highest incompressibility when the mole ratio of FCA to ODA is 1 to 1.
2005, 22(2): 207-209
Abstract:
A novel blue luminescent compound with both hole and electron transplanting groups, 2-(4-(N-ethylcarbazolyl))imidazophenanthroline(ECIP), was synthesized. The composition of the compound was confirmed by elemental analysis, MS and 1H NMR. Uv-Vis absorption, fluorescence, quantum yield determination and thermal analysis indicate this compound is an excellent blue luminescent material.
A novel blue luminescent compound with both hole and electron transplanting groups, 2-(4-(N-ethylcarbazolyl))imidazophenanthroline(ECIP), was synthesized. The composition of the compound was confirmed by elemental analysis, MS and 1H NMR. Uv-Vis absorption, fluorescence, quantum yield determination and thermal analysis indicate this compound is an excellent blue luminescent material.
2005, 22(2): 210-212
Abstract:
1-Chloro-1-fluoroaryl-2-arylethylenes(Ⅲ) prepared from acetyl chloride with arones catalyzed by ZnCl2/SiO2, was dehydrochlorinated to afford diarylacetylenes containing fluorine with an overall yield of 24%~35%. The structures of the compounds were confirmed by IR spectroscopy and MS spectrometry. The influences of different fluorosubstituents on the melting point were investigated.
1-Chloro-1-fluoroaryl-2-arylethylenes(Ⅲ) prepared from acetyl chloride with arones catalyzed by ZnCl2/SiO2, was dehydrochlorinated to afford diarylacetylenes containing fluorine with an overall yield of 24%~35%. The structures of the compounds were confirmed by IR spectroscopy and MS spectrometry. The influences of different fluorosubstituents on the melting point were investigated.
2005, 22(2): 213-215
Abstract:
The present paper covers a new process for the synthesis of 1-(2,6,6-trimethyl-1-cyclohexenyl)-3-methyl-2-buten-4-al with dimethyl sulfide, bromomethane and β-ionone as primary materials in four steps, via the carbine reaction of dimethyl sulfide and bromomethane, the cyclization of trimethylsulfonium bromide and β-ionone, the opening of epoxy compound and isomerization of C14-aldehyde. The overall yield is 77%. The structure of the titled product was characterized by GC/MS, IR and 1H NMR. The process has many advantages such as facile low-cost materials, high conversion, short reaction time, mild reaction ondition, and less by-products. Furthermore, the part materials can be recycled, the cost and pollution are reduced, so it is feasible for industry production.
The present paper covers a new process for the synthesis of 1-(2,6,6-trimethyl-1-cyclohexenyl)-3-methyl-2-buten-4-al with dimethyl sulfide, bromomethane and β-ionone as primary materials in four steps, via the carbine reaction of dimethyl sulfide and bromomethane, the cyclization of trimethylsulfonium bromide and β-ionone, the opening of epoxy compound and isomerization of C14-aldehyde. The overall yield is 77%. The structure of the titled product was characterized by GC/MS, IR and 1H NMR. The process has many advantages such as facile low-cost materials, high conversion, short reaction time, mild reaction ondition, and less by-products. Furthermore, the part materials can be recycled, the cost and pollution are reduced, so it is feasible for industry production.
2005, 22(2): 216-218
Abstract:
Fluoropolymer-modified ployacrylate emulsion was prepared by the copolymerization of methyl methacrylate(MMA), butyl acrylate(BA) and styrene(St) in the presence of swollen particles of PTFE. Compared with acrylate emulsion, the fluoropolymer-modified polyacrylate emulsion exhibits obvious improvements on the quality of the emulsion and latex film. The surface tension and viscosity of the emulsion are 33 mN/m and 1.7 mPa·s, respectively. The minimum film formation temperature(MFT) is 4℃. The film survived 3 000 cycles of water rinse, and the adhesion force is grade one.
Fluoropolymer-modified ployacrylate emulsion was prepared by the copolymerization of methyl methacrylate(MMA), butyl acrylate(BA) and styrene(St) in the presence of swollen particles of PTFE. Compared with acrylate emulsion, the fluoropolymer-modified polyacrylate emulsion exhibits obvious improvements on the quality of the emulsion and latex film. The surface tension and viscosity of the emulsion are 33 mN/m and 1.7 mPa·s, respectively. The minimum film formation temperature(MFT) is 4℃. The film survived 3 000 cycles of water rinse, and the adhesion force is grade one.
2005, 22(2): 219-221
Abstract:
Three pyridylporphyrin-5-fluorouracil compounds, pyridylporphyrin quaternary ammonium bromide, were synthesized by the reaction of monopyridyl trisubstituted phenylporphyrins with 1-(3-bromo-propyl)-5-fluorouracil in refluxing dimethylformamide, and the yield was 32.1%~40.4%. The structures of the products were characterized by elemental analysis, UV-vis, IR, 1H NMR and MS spectro-scopies.
Three pyridylporphyrin-5-fluorouracil compounds, pyridylporphyrin quaternary ammonium bromide, were synthesized by the reaction of monopyridyl trisubstituted phenylporphyrins with 1-(3-bromo-propyl)-5-fluorouracil in refluxing dimethylformamide, and the yield was 32.1%~40.4%. The structures of the products were characterized by elemental analysis, UV-vis, IR, 1H NMR and MS spectro-scopies.
2005, 22(2): 222-223
Abstract:
3-Amino-2-hydroxy-4-phenylbutanoic acid(compound 3), the key intermediate for the synthesis of Bestatin, was prepared via substitution, condensation and reduction in an overall yield of about 47.8%. The reaction of nitromethane with benzyl bromide in the presence of sodium ethoxide gave a 82% yield of 1-nitro-2-phenylethane(compound 1). The condensation of compound 1 with glyoxylic acid monohydrate in sodium ethoxide/ethanol afforded a 72% yield of 3-nitro-2-hydroxy-4-phenylbutyric acid(compound 2), which was hydrogenated to compound 3 with a 81% yield in acetic acid in the presence of Pd/C. All the compounds were characterized by 1H NMR, IR and elemental analysis.
3-Amino-2-hydroxy-4-phenylbutanoic acid(compound 3), the key intermediate for the synthesis of Bestatin, was prepared via substitution, condensation and reduction in an overall yield of about 47.8%. The reaction of nitromethane with benzyl bromide in the presence of sodium ethoxide gave a 82% yield of 1-nitro-2-phenylethane(compound 1). The condensation of compound 1 with glyoxylic acid monohydrate in sodium ethoxide/ethanol afforded a 72% yield of 3-nitro-2-hydroxy-4-phenylbutyric acid(compound 2), which was hydrogenated to compound 3 with a 81% yield in acetic acid in the presence of Pd/C. All the compounds were characterized by 1H NMR, IR and elemental analysis.
2005, 22(2): 224-226
Abstract:
2,4-Dihydroxy-6-methyldeoxybenzoin synthesized from the Hoesch reaction of 3,5-dihydroxytoluene with benzyl cyanide was used to react with triethyl orthoformate by using morpholine as catalyst to form 5-methyl-7-hydroxy-isoflavone. The latter gave the title compound via O-methylation with dimethyl sulfate. The yields of the three steps were 55%, 87% and 56%, respectively. The total yield was about 26%.
2,4-Dihydroxy-6-methyldeoxybenzoin synthesized from the Hoesch reaction of 3,5-dihydroxytoluene with benzyl cyanide was used to react with triethyl orthoformate by using morpholine as catalyst to form 5-methyl-7-hydroxy-isoflavone. The latter gave the title compound via O-methylation with dimethyl sulfate. The yields of the three steps were 55%, 87% and 56%, respectively. The total yield was about 26%.
2005, 22(2): 227-229
Abstract:
Oxidation reaction of tannic acid by I2 was used in the determination of tannic acid in Chinese gall nut by ultraviolet spectrophotometry in aqueous ethanol solution, where I2 exhibits a sensitive absorption at 289 nm. The linear regression equation of the method is A=0.018 61+0.245 3c(mg/L) with a correlation coefficient of 0.999 8. The linear response range is 0.0~2.0 mg/L, the apparent molar absorptivity is 4.14×105 L/(mol·cm) and the recovery is in the range of 97.8%~104.3%. The method has the advantages of simplicity, high sensitivity and rapidity.
Oxidation reaction of tannic acid by I2 was used in the determination of tannic acid in Chinese gall nut by ultraviolet spectrophotometry in aqueous ethanol solution, where I2 exhibits a sensitive absorption at 289 nm. The linear regression equation of the method is A=0.018 61+0.245 3c(mg/L) with a correlation coefficient of 0.999 8. The linear response range is 0.0~2.0 mg/L, the apparent molar absorptivity is 4.14×105 L/(mol·cm) and the recovery is in the range of 97.8%~104.3%. The method has the advantages of simplicity, high sensitivity and rapidity.
2005, 22(2): 230-232
Abstract:
Silver(Ⅰ) oxide was applied to the selective p-tosylation of hydroxyls of saccharide. The reaction of p-methylphenyl-4,6-O-benzylidene-1-thio-β-D-glucopyranoside(A) with a stoichiometric amount of p-toluenesulfonyl chloride(TsCl) in the presence of silver(Ⅰ) oxide and a catalytic amount of potassium iodide selectively led to the monotosylate derivative:p-methylphenyl 3-O-p-toluenesulfonyl-4,6-O-benzylidene-1-thio-β-D-glucopyranoside(B) in a high yield(97%). A possible mechanism of the reaction is proposed. The rational reaction process is that at n(TsCl):n(Ag2O):n(A):n(KI)=1.2:1.5:1.0:0.2, the mixture is stirred at room temperature for 8 h, 2.74 g(97%)B could be isolated from 2.0 g of compound A.
Silver(Ⅰ) oxide was applied to the selective p-tosylation of hydroxyls of saccharide. The reaction of p-methylphenyl-4,6-O-benzylidene-1-thio-β-D-glucopyranoside(A) with a stoichiometric amount of p-toluenesulfonyl chloride(TsCl) in the presence of silver(Ⅰ) oxide and a catalytic amount of potassium iodide selectively led to the monotosylate derivative:p-methylphenyl 3-O-p-toluenesulfonyl-4,6-O-benzylidene-1-thio-β-D-glucopyranoside(B) in a high yield(97%). A possible mechanism of the reaction is proposed. The rational reaction process is that at n(TsCl):n(Ag2O):n(A):n(KI)=1.2:1.5:1.0:0.2, the mixture is stirred at room temperature for 8 h, 2.74 g(97%)B could be isolated from 2.0 g of compound A.
