Login In
2002 Volume 19 Issue 10
2002, 19(10): 919-922
Abstract:
Anatase TiO2 thin films on glass substrate were obtained in an aqueous solution of (NH4)2TiF6 and H3BO3 supersaturated with nano-crystalline TiO2. When the concentration of TiF62- in the aqueous solution was 0.1 mol/L, and the TiF62-/H3BO3 molar ratio was 1:2~1:4 transparent anatase TiO2 thin films could be obtained by deposition at 35℃ followed by calcination. It is found that the film thickness increased with deposition time and achieved 260 nm at a deposition time of 9 h. The photocatalytic activity of the TiO2 thin films was evaluated through catalytic degradation of methylene blue. The TiO2 thin films prepared by calcination at 300℃ showed the strongest photocatalytic activity, which was 5 times the activity of the films prepared without calcination.
Anatase TiO2 thin films on glass substrate were obtained in an aqueous solution of (NH4)2TiF6 and H3BO3 supersaturated with nano-crystalline TiO2. When the concentration of TiF62- in the aqueous solution was 0.1 mol/L, and the TiF62-/H3BO3 molar ratio was 1:2~1:4 transparent anatase TiO2 thin films could be obtained by deposition at 35℃ followed by calcination. It is found that the film thickness increased with deposition time and achieved 260 nm at a deposition time of 9 h. The photocatalytic activity of the TiO2 thin films was evaluated through catalytic degradation of methylene blue. The TiO2 thin films prepared by calcination at 300℃ showed the strongest photocatalytic activity, which was 5 times the activity of the films prepared without calcination.
2002, 19(10): 923-927
Abstract:
Zn100-xTix alloy was prepared by solid phase diffusion method, and its corrosion behavior in alkaline solution was studied by CV. The results indicate that addition of Ti to Zn shifts the corrosion potential Ecorr of alloy electrodes to the more positive level and improves the deposition property of Zn(the active material) during the process of charge-discharge circulation. Alloy electrode with proper Ti content(x=5 et al.) gives a more positive passivating potential hp and higher passive current density, as well as a better reversibility in oxidation and reduction reactions. Titanium eliminates the over-saturation phenomenon of zincate in electrolyte. In other hand, it is found that adding Ti also increases the corrosion current density icorr of alloy electrode, decreases the overpotential of hydrogen evolution and increases anode polarization. The Zn100-xTix alloy electrode with x=5 exhibits the best electrochemical property. Its discharge capacity at 30th and 35th charge-discharge cycle achieves 321 and 278 mA·h/g, respectively.
Zn100-xTix alloy was prepared by solid phase diffusion method, and its corrosion behavior in alkaline solution was studied by CV. The results indicate that addition of Ti to Zn shifts the corrosion potential Ecorr of alloy electrodes to the more positive level and improves the deposition property of Zn(the active material) during the process of charge-discharge circulation. Alloy electrode with proper Ti content(x=5 et al.) gives a more positive passivating potential hp and higher passive current density, as well as a better reversibility in oxidation and reduction reactions. Titanium eliminates the over-saturation phenomenon of zincate in electrolyte. In other hand, it is found that adding Ti also increases the corrosion current density icorr of alloy electrode, decreases the overpotential of hydrogen evolution and increases anode polarization. The Zn100-xTix alloy electrode with x=5 exhibits the best electrochemical property. Its discharge capacity at 30th and 35th charge-discharge cycle achieves 321 and 278 mA·h/g, respectively.
2002, 19(10): 928-931
Abstract:
A novel polymeric complex [(ZnS)2(pn)]n(pn=1,3-propylenediamine) has been synthesized by a solvothermal method from elemental sulfur and zinc(Ⅱ) acetate in 1,3-propylenediamine. Detailed characterizations comfirmed the coordination of pn to ZnS moiety and the construction of the new compound. The compound exhibited a considerably good photocatalytic activity in degradation of a dye reactive violet X-2R and kept nearly the same activity after 10 times repeated experiments.
A novel polymeric complex [(ZnS)2(pn)]n(pn=1,3-propylenediamine) has been synthesized by a solvothermal method from elemental sulfur and zinc(Ⅱ) acetate in 1,3-propylenediamine. Detailed characterizations comfirmed the coordination of pn to ZnS moiety and the construction of the new compound. The compound exhibited a considerably good photocatalytic activity in degradation of a dye reactive violet X-2R and kept nearly the same activity after 10 times repeated experiments.
2002, 19(10): 932-935
Abstract:
The BaTiO3-based PTCR(Positive Temperature Coefficient Resistant) nanopowder was prepared by a modified sol-gel process. XRD, DSC, SEM and BET techniques were used to investigate the characteristics of the nanopowder and their effects on the properties ceramics thereof. The results showed that the sphere-shaped nanopowder of narrow size distribution has an average crysta llite size of 30~40 nm with specific surface area 26.20 m2/g. Its crystal structure is cubic perovskite phase at room temperature. The nanopowder was pressed into pellets and sintered by an improved technique to fabricate PTCR ceramic materials with much better electrical properties than that reported in the previous paper.
The BaTiO3-based PTCR(Positive Temperature Coefficient Resistant) nanopowder was prepared by a modified sol-gel process. XRD, DSC, SEM and BET techniques were used to investigate the characteristics of the nanopowder and their effects on the properties ceramics thereof. The results showed that the sphere-shaped nanopowder of narrow size distribution has an average crysta llite size of 30~40 nm with specific surface area 26.20 m2/g. Its crystal structure is cubic perovskite phase at room temperature. The nanopowder was pressed into pellets and sintered by an improved technique to fabricate PTCR ceramic materials with much better electrical properties than that reported in the previous paper.
2002, 19(10): 936-940
Abstract:
MnO2 and Fe3+ doped MnO2 used as electrode materials were prepared by solid state reaction and characterized by XRD and SEM. The latter showed better electrochemical performances. The specific capacitances of pure MnO2 and iron doped MnO2 were 311~149 F/g and 318~114 F/g(mass of single electrode active matter), respectively, at current density of 50~1000 mA/g. The specific energy values of supercapacitors fabricated by these materials were 27.6~9.95 W·h/Kg and 28~10 W·h/Kg, respectively. It appeared that the ratio of Fe3+ in samples had greater effect on the electrochemical capacity. The better discharge capacity could be obtained when the mole ratio of Mn(Ⅳ) to Fe(Ⅲ) was 10. The capacitors consisted of modified MnO2 was more stable in cycling than those made of MnO2 and their specific capacitance after 1000 cycles decreased to 90% and 70%, respectively, at current density 1000 mA/g.
MnO2 and Fe3+ doped MnO2 used as electrode materials were prepared by solid state reaction and characterized by XRD and SEM. The latter showed better electrochemical performances. The specific capacitances of pure MnO2 and iron doped MnO2 were 311~149 F/g and 318~114 F/g(mass of single electrode active matter), respectively, at current density of 50~1000 mA/g. The specific energy values of supercapacitors fabricated by these materials were 27.6~9.95 W·h/Kg and 28~10 W·h/Kg, respectively. It appeared that the ratio of Fe3+ in samples had greater effect on the electrochemical capacity. The better discharge capacity could be obtained when the mole ratio of Mn(Ⅳ) to Fe(Ⅲ) was 10. The capacitors consisted of modified MnO2 was more stable in cycling than those made of MnO2 and their specific capacitance after 1000 cycles decreased to 90% and 70%, respectively, at current density 1000 mA/g.
2002, 19(10): 941-945
Abstract:
Organic ligands containing the thiol(-SH) metal-chelating functional group were grafted to the surface of a mesoporous molecular sieve MCM-41 prepared from tetraethylorthosilicate, tetra methylanmonium hydroxide and hexadecyl trimethyl ammonium bromide. X-ray diffraction, infrared spectroscopy, elemental analysis, thermogravimetric analysis, 29Si and 13C solid-state NMR spectroscopy results demonstrated the presence of the organic ligands in the modified thiol-functionalized material(designated as MP-MCM-41). MP-MCM-41 was found to be highly effective for the adsorption of Hg(Ⅱ), Pb(Ⅱ), and Cd(Ⅱ) ions, exhibiting high metal ion uptake capacities of 148.20, 135.76, and 36.50 mg/g-1, respectively. The adsorption was fitted to Langmuir isotherms.
Organic ligands containing the thiol(-SH) metal-chelating functional group were grafted to the surface of a mesoporous molecular sieve MCM-41 prepared from tetraethylorthosilicate, tetra methylanmonium hydroxide and hexadecyl trimethyl ammonium bromide. X-ray diffraction, infrared spectroscopy, elemental analysis, thermogravimetric analysis, 29Si and 13C solid-state NMR spectroscopy results demonstrated the presence of the organic ligands in the modified thiol-functionalized material(designated as MP-MCM-41). MP-MCM-41 was found to be highly effective for the adsorption of Hg(Ⅱ), Pb(Ⅱ), and Cd(Ⅱ) ions, exhibiting high metal ion uptake capacities of 148.20, 135.76, and 36.50 mg/g-1, respectively. The adsorption was fitted to Langmuir isotherms.
2002, 19(10): 946-949
Abstract:
The coordination adsorption resins were prepared by loading different transition metal ions on macroporous sulphonic resin(D72) and acrylic acid resin(D152) respectively, and the coordination adsorption of VB12 on the resins in various media has been investigated. The sulphonic resin loaded with Zn2+ (D72Zn2+) was found to possess the best adsorption and desorption properties. The adsorption isotherm of VB12 on D72Zn2+ resin in ethanol fits the Langmuir adsorption equation, and the saturated adsorption capacity from ethanol reaches 61 mg/g. The leakage capacity by column operation was 34 mg/g and water appeared an effective eluant with 94% desorption percentage.
The coordination adsorption resins were prepared by loading different transition metal ions on macroporous sulphonic resin(D72) and acrylic acid resin(D152) respectively, and the coordination adsorption of VB12 on the resins in various media has been investigated. The sulphonic resin loaded with Zn2+ (D72Zn2+) was found to possess the best adsorption and desorption properties. The adsorption isotherm of VB12 on D72Zn2+ resin in ethanol fits the Langmuir adsorption equation, and the saturated adsorption capacity from ethanol reaches 61 mg/g. The leakage capacity by column operation was 34 mg/g and water appeared an effective eluant with 94% desorption percentage.
2002, 19(10): 950-953
Abstract:
By using Zn-Hg as reductant alkylferrocences were prepared through reducing acylferrocenes synthesized using acyl chloride as acylating agents and anhydrous aluminum chloride as catalyst. The alkylferrocenes were characterized by elemental analysis, IR spectrum and refractive index measurements. The electrochemical properties of the series alkylferrocenes were investigated by cyclic voltammetry. The catalytic burning-rate of composite solid propellants with the compounds obtained were tested.
By using Zn-Hg as reductant alkylferrocences were prepared through reducing acylferrocenes synthesized using acyl chloride as acylating agents and anhydrous aluminum chloride as catalyst. The alkylferrocenes were characterized by elemental analysis, IR spectrum and refractive index measurements. The electrochemical properties of the series alkylferrocenes were investigated by cyclic voltammetry. The catalytic burning-rate of composite solid propellants with the compounds obtained were tested.
2002, 19(10): 954-957
Abstract:
EP/LDH composite materials were prepared by adding LDH(Layered Double Hydroxide) to epoxy resin(EP). Oxygen index and smoke density in condition of no flame combustion for EP/LDH composite materials were determined. The flame retardancy and smoke suppression effects of LDH nanomaterials on EP were investigated. Smoke suppression mechanism of LDH was discussed. The results showed that the oxygen index of EP has increased slightly, but the smoke suppression effect was remarkable when LDH was added in 20~60 parts per 100 parts of resin. It is suggested that the porous thermal decomposed products of LDH with large specific surface area give smoke suppression effects by adsorbing the smoke and gases produced in the course of combustion.
EP/LDH composite materials were prepared by adding LDH(Layered Double Hydroxide) to epoxy resin(EP). Oxygen index and smoke density in condition of no flame combustion for EP/LDH composite materials were determined. The flame retardancy and smoke suppression effects of LDH nanomaterials on EP were investigated. Smoke suppression mechanism of LDH was discussed. The results showed that the oxygen index of EP has increased slightly, but the smoke suppression effect was remarkable when LDH was added in 20~60 parts per 100 parts of resin. It is suggested that the porous thermal decomposed products of LDH with large specific surface area give smoke suppression effects by adsorbing the smoke and gases produced in the course of combustion.
2002, 19(10): 958-962
Abstract:
25, 26, 27, 28-Tetraethoxycarbonylmethoxy calix [4]arene(3) was synthesized by reacting calix [4]arene(2) with ethyl bromoacetate using K2CO3 as base in acetone. The structure of (3) was characterized by elmenetal analysis, IR, UV, MS, 1H and 13C NMR spectra. Compound 3 exist in "partial cone" conformations. The coordination behavior of the compound with four rare earth metal(Ⅲ) nitrates in acetonitrile were studied by fluorescence spectrometry. The stability constants(lg Ks) of the complexes of 3 with rare earth metal(Ⅲ) nitrates and Gibbs free energy change(-ΔG0) of the coordination reactions were calculated according to the modified Hilderbrand-Benesi equation. The calix [4]arene obtained exhibited a strong coordination ability with rare earth nitrates and good transportability for alkali metal ions throungh liquid membrane in order of Na+> K+> Li+.
25, 26, 27, 28-Tetraethoxycarbonylmethoxy calix [4]arene(3) was synthesized by reacting calix [4]arene(2) with ethyl bromoacetate using K2CO3 as base in acetone. The structure of (3) was characterized by elmenetal analysis, IR, UV, MS, 1H and 13C NMR spectra. Compound 3 exist in "partial cone" conformations. The coordination behavior of the compound with four rare earth metal(Ⅲ) nitrates in acetonitrile were studied by fluorescence spectrometry. The stability constants(lg Ks) of the complexes of 3 with rare earth metal(Ⅲ) nitrates and Gibbs free energy change(-ΔG0) of the coordination reactions were calculated according to the modified Hilderbrand-Benesi equation. The calix [4]arene obtained exhibited a strong coordination ability with rare earth nitrates and good transportability for alkali metal ions throungh liquid membrane in order of Na+> K+> Li+.
2002, 19(10): 963-967
Abstract:
In quantum chemical studies on enantioselective reductions small model molecules are comonly used to substitute the reactants as reported in literatures. It results in certain neglect of important chemical information. In this paper, the semi-empirical AM1 molecular orbital method is used to study the enantioselective reduction of aromatic ketone catalyzed by chiral pyrrolidino [3,4-c] oxazaborolidine without model substituents. As illustrated, this enantioselective reduction is exothermic. In the transition states of hydrogen atom from the borane moiety to the carbonyl carbon of aromatic ketone, there is a 6-membered B-N-B-H-C-O ring in a twisted chair structure. The controlling step for the reduction is the decomposition of the catalyst:alkoxyborane which contains a B-O-B-N ring.
In quantum chemical studies on enantioselective reductions small model molecules are comonly used to substitute the reactants as reported in literatures. It results in certain neglect of important chemical information. In this paper, the semi-empirical AM1 molecular orbital method is used to study the enantioselective reduction of aromatic ketone catalyzed by chiral pyrrolidino [3,4-c] oxazaborolidine without model substituents. As illustrated, this enantioselective reduction is exothermic. In the transition states of hydrogen atom from the borane moiety to the carbonyl carbon of aromatic ketone, there is a 6-membered B-N-B-H-C-O ring in a twisted chair structure. The controlling step for the reduction is the decomposition of the catalyst:alkoxyborane which contains a B-O-B-N ring.
2002, 19(10): 968-971
Abstract:
Polyethylene-1,4-dithio-carboxyl piperazine(Pzdtc) was prepared in solid state at temperature below 10℃ and characterized. Its sorption and desorption properties towards a series of heavy metal ions and aniline in waste water were examined. The results showed that the polymer could adsorb heavy metal ions in certain amount. Its adsorption capacity for Ag+ and Pd2+ was 98.2% and 95.4%, respectively. The concentration of aniline in waste water could be reduced from 500 mg/L to about 10 mg/L after treatment by the polymer. The polymeric adsorbent could be reused repeatedly after regeneration.
Polyethylene-1,4-dithio-carboxyl piperazine(Pzdtc) was prepared in solid state at temperature below 10℃ and characterized. Its sorption and desorption properties towards a series of heavy metal ions and aniline in waste water were examined. The results showed that the polymer could adsorb heavy metal ions in certain amount. Its adsorption capacity for Ag+ and Pd2+ was 98.2% and 95.4%, respectively. The concentration of aniline in waste water could be reduced from 500 mg/L to about 10 mg/L after treatment by the polymer. The polymeric adsorbent could be reused repeatedly after regeneration.
2002, 19(10): 972-975
Abstract:
Nano-semiconductive material SO42-/La-T-Fe2O3 has been characterized by means of IR、XPS and specific surface area measurements. The ethanol sensors were fabricated with the nano powders. The results indicated that SO42- is combined with Fe3+ of La-T-Fe2O3 through an inorganic bridge structure. Addition of SO42- makes the binding energy of Fep1/3 increased from 710.85 eV to 712.10 eV and Fe3+ became more positive in charge, thus, the semicudutivity of La-T-Fe2O3 is changed from the p-type into the n-type. The sensor fabricated from SO42-/La-T-Fe2O3, calcinated at 450℃ showed sensitivity of 35.7 to ethyl alcohol and good stability.
Nano-semiconductive material SO42-/La-T-Fe2O3 has been characterized by means of IR、XPS and specific surface area measurements. The ethanol sensors were fabricated with the nano powders. The results indicated that SO42- is combined with Fe3+ of La-T-Fe2O3 through an inorganic bridge structure. Addition of SO42- makes the binding energy of Fep1/3 increased from 710.85 eV to 712.10 eV and Fe3+ became more positive in charge, thus, the semicudutivity of La-T-Fe2O3 is changed from the p-type into the n-type. The sensor fabricated from SO42-/La-T-Fe2O3, calcinated at 450℃ showed sensitivity of 35.7 to ethyl alcohol and good stability.
2002, 19(10): 976-980
Abstract:
The activities of Pd/C、Pd-Co/C catalysts have been evaluated in a self-made batch reactor and characterized by BET、XRD and XPS techniques. The results show that Pd-Co/C catalyst exhibits the glucose conversion activity of 92%, with 94% selectivity to glucose acid after reaction for 3 h. The BET measurement reveals the increased distribution of the larger pore size of Pd-Co/C catalyst in comparison with that of Pd/C as a result of the addition of Co and the sequent catalyst calcination. The XPS characterization indicates higher concentration and dispersion of palladium species on the surface of Pd-Co/C catalysts compared with Pd/C catalyst. This suggests the easy reduction of the Pd species located on the surface of Pd-Co/C catalysts. The Pd-Co/C catalyst exhibits better catalytic performance for oxidation of glucose than Pd/C catalyst.
The activities of Pd/C、Pd-Co/C catalysts have been evaluated in a self-made batch reactor and characterized by BET、XRD and XPS techniques. The results show that Pd-Co/C catalyst exhibits the glucose conversion activity of 92%, with 94% selectivity to glucose acid after reaction for 3 h. The BET measurement reveals the increased distribution of the larger pore size of Pd-Co/C catalyst in comparison with that of Pd/C as a result of the addition of Co and the sequent catalyst calcination. The XPS characterization indicates higher concentration and dispersion of palladium species on the surface of Pd-Co/C catalysts compared with Pd/C catalyst. This suggests the easy reduction of the Pd species located on the surface of Pd-Co/C catalysts. The Pd-Co/C catalyst exhibits better catalytic performance for oxidation of glucose than Pd/C catalyst.
2002, 19(10): 981-984
Abstract:
Monodispersed polymethyl metharylate(PMMA) microspheres were synthesized by emulsifier-free emulsion polymerization under the microwave irradiation. 2,2'-Azobis(2-methylpropionamidine)dihydro chloride(AIBA) and potassium persulphate(KPS) were used as cationic and anionic initiators. The effects of initiator, heating ways and monomer concentration on the particle size, uniformity and polymerization rate were discussed. By using AIBA as an initiator, the diameter of particle obtained was smaller than the corresponding polymer particles initiated by KPS, but the polymerization rate was more rapid to give more particles. Increasing the monomer concentration increased the particle diameter but decreased the conversion rate and the number of particles. In comparison with the conventional heating method, microwave irradiation could shorten the polymerization time and give more particles with smaller particle diameter.
Monodispersed polymethyl metharylate(PMMA) microspheres were synthesized by emulsifier-free emulsion polymerization under the microwave irradiation. 2,2'-Azobis(2-methylpropionamidine)dihydro chloride(AIBA) and potassium persulphate(KPS) were used as cationic and anionic initiators. The effects of initiator, heating ways and monomer concentration on the particle size, uniformity and polymerization rate were discussed. By using AIBA as an initiator, the diameter of particle obtained was smaller than the corresponding polymer particles initiated by KPS, but the polymerization rate was more rapid to give more particles. Increasing the monomer concentration increased the particle diameter but decreased the conversion rate and the number of particles. In comparison with the conventional heating method, microwave irradiation could shorten the polymerization time and give more particles with smaller particle diameter.
2002, 19(10): 985-988
Abstract:
The influence of montmorillonite(Mont.) on melting and crystallization behavior of nylon 66 has been investigated by DSC. The results show that the melting and crystallization temperature of nylon 66 were increased by 0.5℃ and 13~24℃ respectively after adding 4.76%(by mass) of organophilic montmorillonite. The occurance of two melting peaks of PA66 and composites may be resulted from the differences of the crystal types. Addition of montmorillonite favored the production of 2 peeks in the second melting process.
The influence of montmorillonite(Mont.) on melting and crystallization behavior of nylon 66 has been investigated by DSC. The results show that the melting and crystallization temperature of nylon 66 were increased by 0.5℃ and 13~24℃ respectively after adding 4.76%(by mass) of organophilic montmorillonite. The occurance of two melting peaks of PA66 and composites may be resulted from the differences of the crystal types. Addition of montmorillonite favored the production of 2 peeks in the second melting process.
2002, 19(10): 989-993
Abstract:
2-Methyl-3-(3,4-methylenedioxyphenyl)acraldehyde was synthesized through Claisen-Schmidt condensation reaction of the heliotropin and propanal with KF/Al2O3 as a catalyst, in yield over 80%. The catalytic activity of KF/Al2O3 was much higher than that of the common alkali catalysts. The catalyst KF/Al2O3 was characterized by BET, TPD, XRD and XPS. The existence of F- and [Al-O-] on KF/Al2O3 catalyst and their synergetic effects make KF/Al2O3 a good catalyst for Claisen-Schmidt condensation reaction.
2-Methyl-3-(3,4-methylenedioxyphenyl)acraldehyde was synthesized through Claisen-Schmidt condensation reaction of the heliotropin and propanal with KF/Al2O3 as a catalyst, in yield over 80%. The catalytic activity of KF/Al2O3 was much higher than that of the common alkali catalysts. The catalyst KF/Al2O3 was characterized by BET, TPD, XRD and XPS. The existence of F- and [Al-O-] on KF/Al2O3 catalyst and their synergetic effects make KF/Al2O3 a good catalyst for Claisen-Schmidt condensation reaction.
2002, 19(10): 994-997
Abstract:
The catalytic activities of supported palladium catalysts for the synthesis of diethyl carbonate (DEC) in vapor phase have been studied in a fixed-bed reactor. The catalysts were prepared by impregnating Si-MCM-41(SiM) and Ti-MCM-41(TiM) powder in corresponding solution of PdCl2, CuCl2·2H2O and (C4H9O)4Ti. The results revealed that addition of copper and titanium increased the yields of both DEC and diethyl oxalate(DEO). The catalytic activity of the catalysts supported on SiM was higher than that of the catalysts supported on TiM. Copper and titanium function differently in on the catalyts: with SiM as support, Cu was in favorable of DEO formation, while Ti is of DEC formation. In the case of TiM as support, however, two additives showed opposite results. The above results suggested the support and the additive have synergistic action on the reaction of CO with C2H5ONO.
The catalytic activities of supported palladium catalysts for the synthesis of diethyl carbonate (DEC) in vapor phase have been studied in a fixed-bed reactor. The catalysts were prepared by impregnating Si-MCM-41(SiM) and Ti-MCM-41(TiM) powder in corresponding solution of PdCl2, CuCl2·2H2O and (C4H9O)4Ti. The results revealed that addition of copper and titanium increased the yields of both DEC and diethyl oxalate(DEO). The catalytic activity of the catalysts supported on SiM was higher than that of the catalysts supported on TiM. Copper and titanium function differently in on the catalyts: with SiM as support, Cu was in favorable of DEO formation, while Ti is of DEC formation. In the case of TiM as support, however, two additives showed opposite results. The above results suggested the support and the additive have synergistic action on the reaction of CO with C2H5ONO.
2002, 19(10): 998-1001
Abstract:
Glucose was electrocatalytically hydrogenated to sorbitol on the hydrogen-storage alloy(RENi3.9Co0.59Mn0.28Al0.22) cathode where RE composed of 0.80 La, 0.02 Ce, 0.15 Nd, 0.04 Pr and trace Zr. The mass ratio of alloy powder to PTFE mixed in course of electrode preparation affects the cathode capability. At optimum condition:40℃, pH=12, current density 0.5 A/dm2, catholyte containing 0.4 mol/L glucose and 0.5 mol/L sodium sulfate sorbitol in yield of 80% can be obtained, with current efficiency of 67%. It is suggested based on CV results that the active hydrogen atoms on the surface of hydrogen-storage alloy cathode initiate the hydrogenation of glucose to sorbitol.
Glucose was electrocatalytically hydrogenated to sorbitol on the hydrogen-storage alloy(RENi3.9Co0.59Mn0.28Al0.22) cathode where RE composed of 0.80 La, 0.02 Ce, 0.15 Nd, 0.04 Pr and trace Zr. The mass ratio of alloy powder to PTFE mixed in course of electrode preparation affects the cathode capability. At optimum condition:40℃, pH=12, current density 0.5 A/dm2, catholyte containing 0.4 mol/L glucose and 0.5 mol/L sodium sulfate sorbitol in yield of 80% can be obtained, with current efficiency of 67%. It is suggested based on CV results that the active hydrogen atoms on the surface of hydrogen-storage alloy cathode initiate the hydrogenation of glucose to sorbitol.
2002, 19(10): 1002-1004
Abstract:
A series of water soluble N-maleoyl chitosan was synthesized in an acid homogeneous solution. Their chemical structure were demonstrated by FTIR and UV spectra. The effects of the mole ratio of anhydride to amino group of chitosan in feed solution on the solubility, intrinsic viscosity([Z]) and the yield of product were studied. The results showed that the solubility of N-maleoyl chitosan was greatly improved in water. The highest yield was obtained at 0.5 mole ratio of maleic anhydride to chitosan.
A series of water soluble N-maleoyl chitosan was synthesized in an acid homogeneous solution. Their chemical structure were demonstrated by FTIR and UV spectra. The effects of the mole ratio of anhydride to amino group of chitosan in feed solution on the solubility, intrinsic viscosity([Z]) and the yield of product were studied. The results showed that the solubility of N-maleoyl chitosan was greatly improved in water. The highest yield was obtained at 0.5 mole ratio of maleic anhydride to chitosan.
2002, 19(10): 1005-1007
Abstract:
The oxidation stability and reaction kinetics of multi-wall carbon nanotubes(MWCNTs), graphite and C60 have been studied by TG-DTA techniques. The maximum mass losses were found at 673℃(carbon nanotubes), 846℃(graphite) and 628℃(C60), respectively, at a heating rate of 10℃/min. The apparent activation energy of the oxidation reaction of carbon nanotubes, graphite and C60 are E(MWCNTs)=143.5 kJ/mol、 E(graphite)=180.7 kJ/mol、 E(C60)=90.9 kJ/mol, respectively. The reaction order of the oxidation reaction of carbon nanotubes, graphite and C60 are n(MWCNTs)=3/5、n(graphite)=1/2、n(C60)=1/2, respectively. In conclusion, graphite has the best resistance to oxidation, but C60 the weakest.
The oxidation stability and reaction kinetics of multi-wall carbon nanotubes(MWCNTs), graphite and C60 have been studied by TG-DTA techniques. The maximum mass losses were found at 673℃(carbon nanotubes), 846℃(graphite) and 628℃(C60), respectively, at a heating rate of 10℃/min. The apparent activation energy of the oxidation reaction of carbon nanotubes, graphite and C60 are E(MWCNTs)=143.5 kJ/mol、 E(graphite)=180.7 kJ/mol、 E(C60)=90.9 kJ/mol, respectively. The reaction order of the oxidation reaction of carbon nanotubes, graphite and C60 are n(MWCNTs)=3/5、n(graphite)=1/2、n(C60)=1/2, respectively. In conclusion, graphite has the best resistance to oxidation, but C60 the weakest.
2002, 19(10): 1008-1010
Abstract:
Seven-2-(4-substituted styryl)benzothiazoles were synthesized by reacting 2-methylbenzothiazole with aromatic aldehydes by microwave irradiation. Aqueous sodium hydroxide(50%) was used as catalyt and dimethyl sulfoxide(DMSO)as solvent. The reaction could be completed in 2~5 min with yields of 30%~93%.
Seven-2-(4-substituted styryl)benzothiazoles were synthesized by reacting 2-methylbenzothiazole with aromatic aldehydes by microwave irradiation. Aqueous sodium hydroxide(50%) was used as catalyt and dimethyl sulfoxide(DMSO)as solvent. The reaction could be completed in 2~5 min with yields of 30%~93%.
2002, 19(10): 1011-1013
Abstract:
An assembled Mg2Al-CO3-SO4 hydrotalcite has been prepared by ion-exchanging of Mg2Al-CO3 hydrotalcite with SO42-. The Mg2Al-CO3-SO4 hydrotalcite obtained has well-formed crystal structure and performs higher selective IR adsorption function than Mg2Al-CO3 hydrotalcite.
An assembled Mg2Al-CO3-SO4 hydrotalcite has been prepared by ion-exchanging of Mg2Al-CO3 hydrotalcite with SO42-. The Mg2Al-CO3-SO4 hydrotalcite obtained has well-formed crystal structure and performs higher selective IR adsorption function than Mg2Al-CO3 hydrotalcite.
2002, 19(10): 1014-1015
Abstract:
5-Methoxyindole was synthesized in 4 steps starting from m-cresol through nitrosation oxidation, etherification, condensation and reduction-cyclization. The protecting piperidine group was at last removed from the enamine with Raney nickel as catalyst to give 5-methoxyindole. The total yield was 34.3%.
5-Methoxyindole was synthesized in 4 steps starting from m-cresol through nitrosation oxidation, etherification, condensation and reduction-cyclization. The protecting piperidine group was at last removed from the enamine with Raney nickel as catalyst to give 5-methoxyindole. The total yield was 34.3%.
2002, 19(10): 1016-1017
Abstract:
The divalent Sm complex supported by Schiff base ligand [2-OC6H4CH=N(2,6-iPr2C6H3)]2Sm(THF)2 has been prepared by the reaction of [2-OC6H4CH=N(2,6-iPr2C6H3)]2Na with SmI2 in THF. It exhibits a good catalytic activity for the polymerization of X-caprolactone, and the polymer obtained has a narrow molecular weight distribution.
The divalent Sm complex supported by Schiff base ligand [2-OC6H4CH=N(2,6-iPr2C6H3)]2Sm(THF)2 has been prepared by the reaction of [2-OC6H4CH=N(2,6-iPr2C6H3)]2Na with SmI2 in THF. It exhibits a good catalytic activity for the polymerization of X-caprolactone, and the polymer obtained has a narrow molecular weight distribution.
2002, 19(10): 1018-1020
Abstract:
A series of 2-amino-3-cyano-4-aryl-4H-benzo[h]chromenes were synehesized by the reaction of malononitrile and 1-naphthol with corresponding aromatic aldehydes in ethanol in the presence of piperidine as catalyst. The structures of all compounds obtained were characterized by elemental analysis, IR, 1H NMR and single crystal X-ray diffractometry. X-ray crystal structure analysis indicates compound 4b crystallizes in monoclinic, with space group C2/c, a=2.4221(6) nm, b=0.9016(2) nm, c=1.7003(5) nm, U=93.16(1)°, V=3.7074(15) nm3, Z=8, Dc=1.284 g/cm3, I≥2e(I)=2141, R=0.0432, wR=0.1085. Compared to other methods, this method has the advantages of simple operation and good yields.
A series of 2-amino-3-cyano-4-aryl-4H-benzo[h]chromenes were synehesized by the reaction of malononitrile and 1-naphthol with corresponding aromatic aldehydes in ethanol in the presence of piperidine as catalyst. The structures of all compounds obtained were characterized by elemental analysis, IR, 1H NMR and single crystal X-ray diffractometry. X-ray crystal structure analysis indicates compound 4b crystallizes in monoclinic, with space group C2/c, a=2.4221(6) nm, b=0.9016(2) nm, c=1.7003(5) nm, U=93.16(1)°, V=3.7074(15) nm3, Z=8, Dc=1.284 g/cm3, I≥2e(I)=2141, R=0.0432, wR=0.1085. Compared to other methods, this method has the advantages of simple operation and good yields.
