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2002 Volume 19 Issue 3
2002, 19(3): 205-211
Abstract:
Receat progresses on the asymmetric aziridination reactions of olefins during the last twenty years are reviewed with emphesis on the metal complex catalysts, such as porphyrin, bis oxazoline and Salen ligands.
Receat progresses on the asymmetric aziridination reactions of olefins during the last twenty years are reviewed with emphesis on the metal complex catalysts, such as porphyrin, bis oxazoline and Salen ligands.
2002, 19(3): 212-215
Abstract:
N-substituted cyclododecanone thiosemicarbazones(4) were synthesized by condensation reaction of cyclododecanone and N-substituted thiosemicarbazide. 4 undergo oxidative cyclisation on treatment with manganese dioxide to give title compounds, 2-(1,11-undecylidene)-5-substituted imino Δ3-1,3,4-thiadiazoline(5). The structure of 5 were confirmed by IR, 13C NMR and elemental analysis. Preliminary bioassays showed that compounds 5 have some fungicidal activity.
N-substituted cyclododecanone thiosemicarbazones(4) were synthesized by condensation reaction of cyclododecanone and N-substituted thiosemicarbazide. 4 undergo oxidative cyclisation on treatment with manganese dioxide to give title compounds, 2-(1,11-undecylidene)-5-substituted imino Δ3-1,3,4-thiadiazoline(5). The structure of 5 were confirmed by IR, 13C NMR and elemental analysis. Preliminary bioassays showed that compounds 5 have some fungicidal activity.
2002, 19(3): 216-219
Abstract:
Crude chitosan powder was degraded by HCl or H3PO4 water/ethanol solution to give two kinds of water-soluble microcrystalline chitosan with diameters being inrange of 400 nm to 800 nm. In IR spectra acetamide bands of crude chitosan(at 1650, 1600 cm-1) disappeared completely, and instead, the asymmetric distortion vibration and symmetric distortion vibration bands of -NH3+ were observed at 1 620, 1 520 cm-1. The microcrystalline chitosan prepared by acidolysis with HCl solution dissolved in clod water; and that with H3PO4 solution dissolved in water only at 60℃.
Crude chitosan powder was degraded by HCl or H3PO4 water/ethanol solution to give two kinds of water-soluble microcrystalline chitosan with diameters being inrange of 400 nm to 800 nm. In IR spectra acetamide bands of crude chitosan(at 1650, 1600 cm-1) disappeared completely, and instead, the asymmetric distortion vibration and symmetric distortion vibration bands of -NH3+ were observed at 1 620, 1 520 cm-1. The microcrystalline chitosan prepared by acidolysis with HCl solution dissolved in clod water; and that with H3PO4 solution dissolved in water only at 60℃.
2002, 19(3): 220-223
Abstract:
The effects of the amount of hydrophilic monomer acrylic acid(AA) and initiator benzoyl peroxide(BPO) in polymerization of acrylate terpolymer (consisted of methylmethacrylate(MMA), butyl acrylate(BA) and acrylic acid) on the properties of the acrylate terpolymer soap free hydrosol have been studied. The optimum contents of h(AA) 4% and c (BPO) 1.8×10-2g/mL were selected. The terpolymer was identified by IR, 1H NMR and GPC. The hydrosol obtained had viscosity 20.5 mPa·s (D200s-1), surface tension 31 mN/m and an improved stability, meeting the basic requirements of water based ink.
The effects of the amount of hydrophilic monomer acrylic acid(AA) and initiator benzoyl peroxide(BPO) in polymerization of acrylate terpolymer (consisted of methylmethacrylate(MMA), butyl acrylate(BA) and acrylic acid) on the properties of the acrylate terpolymer soap free hydrosol have been studied. The optimum contents of h(AA) 4% and c (BPO) 1.8×10-2g/mL were selected. The terpolymer was identified by IR, 1H NMR and GPC. The hydrosol obtained had viscosity 20.5 mPa·s (D200s-1), surface tension 31 mN/m and an improved stability, meeting the basic requirements of water based ink.
2002, 19(3): 224-229
Abstract:
The effects of the amount of crosslinking agent zirconium chelate ZrE on the properties of acrylate hydrosol and hydrosol film at different temperatures were discussed. In copolymer hydrosol, ZrE could interact with copolymer and change the hydrosol viscosity, surface tension and stability, and also improve the water resistance of the hydrosol film. IR, 1H NMR, DSC, TGA and UV analysis were used to study the reaction mechanism.
The effects of the amount of crosslinking agent zirconium chelate ZrE on the properties of acrylate hydrosol and hydrosol film at different temperatures were discussed. In copolymer hydrosol, ZrE could interact with copolymer and change the hydrosol viscosity, surface tension and stability, and also improve the water resistance of the hydrosol film. IR, 1H NMR, DSC, TGA and UV analysis were used to study the reaction mechanism.
2002, 19(3): 230-233
Abstract:
A series of poly(amic acid)s(PAA) based on pyromellitic dianhydride(PMDA), biphenyl tetracarboxylic dianhydride(BPDA), thiodiphthalic dianhydride(TDPA), bis(dicarboxyphenoxy) benzene dianhydride(HQDPA) and oxydiphthalo tetracarboxylic dianhydride(ODPA) were prepared in different solvents. Two poly(amic acid)s, from PMDA with 4,4'-diaminodiphenyl methane or 4,4'-diamino 3,3'-dimethyl diphenyl methane, were found to be gelatinized in N-methyl pyrrolidone, and the other PAAs were soluble at room temperature. The storage stability of the poly(amic acid)s were investigated as function of temperature, gel state, addition of molecular sieve. The poly(amic acid) gels showed better storage stability than poly(amic acid)s solutions. 4A molecular sieve could prevent poly(amic acid)s from depolymerization, leading to a long time storage.
A series of poly(amic acid)s(PAA) based on pyromellitic dianhydride(PMDA), biphenyl tetracarboxylic dianhydride(BPDA), thiodiphthalic dianhydride(TDPA), bis(dicarboxyphenoxy) benzene dianhydride(HQDPA) and oxydiphthalo tetracarboxylic dianhydride(ODPA) were prepared in different solvents. Two poly(amic acid)s, from PMDA with 4,4'-diaminodiphenyl methane or 4,4'-diamino 3,3'-dimethyl diphenyl methane, were found to be gelatinized in N-methyl pyrrolidone, and the other PAAs were soluble at room temperature. The storage stability of the poly(amic acid)s were investigated as function of temperature, gel state, addition of molecular sieve. The poly(amic acid) gels showed better storage stability than poly(amic acid)s solutions. 4A molecular sieve could prevent poly(amic acid)s from depolymerization, leading to a long time storage.
2002, 19(3): 234-238
Abstract:
Some glycidol ether monomer(GE) were prepared by reacting epichlorohydrin(ECH) with phenol and/or alcohol; T-allyl glycidol ether, U-chloroethyl glycidol ether, benzene glycidol ether, m-tolyl glycidol ether, benzyl glycidol ether. And aliphatic polycarbonates were synthesized by copolymerization of CO2 with GE catalyzed by coordination catalyst composed of Y phosphonate and triisobutylaluminum[Y(P204)3-Al(i-Bu)3]. The copolymers were characterized by IR, 1H NMR, 13C NMR, WXRD, TG and dynamic mechanical analysis. The results showed that Y(P204)3-Al(i-Bu)32 with GE and the preferred amount of catalyst was 2.7×10-2~5.0×10-2mol/L. The thermal analysis revealed the thermal resistance of the copolymers prepared by CO2 and GE with benzene ring was higher than that of the copolymer prepared by CO2 and ECH. The glass transition temperature of the m-tolyl glycidol ether-CO2 copolymer was 26.6℃.
Some glycidol ether monomer(GE) were prepared by reacting epichlorohydrin(ECH) with phenol and/or alcohol; T-allyl glycidol ether, U-chloroethyl glycidol ether, benzene glycidol ether, m-tolyl glycidol ether, benzyl glycidol ether. And aliphatic polycarbonates were synthesized by copolymerization of CO2 with GE catalyzed by coordination catalyst composed of Y phosphonate and triisobutylaluminum[Y(P204)3-Al(i-Bu)3]. The copolymers were characterized by IR, 1H NMR, 13C NMR, WXRD, TG and dynamic mechanical analysis. The results showed that Y(P204)3-Al(i-Bu)32 with GE and the preferred amount of catalyst was 2.7×10-2~5.0×10-2mol/L. The thermal analysis revealed the thermal resistance of the copolymers prepared by CO2 and GE with benzene ring was higher than that of the copolymer prepared by CO2 and ECH. The glass transition temperature of the m-tolyl glycidol ether-CO2 copolymer was 26.6℃.
Synthesis and Properties of Poly(aryl ether)s Containing o-substituted-phenyl Phthalazinone Moieties
2002, 19(3): 239-242
Abstract:
A series of novel poly(aryl ether)s:poly(ether sulfone)(PPES), poly(ether ketone)(PPEK) and their copolymer poly(ether sulfone ketone)(PPESK) were synthesized at high temperature by nucleophilic polycondensation of bisphenol 4-(3-phenyl 4-hydroxyphenyl)-2,3-phthalazin-1-one(OP-DHPZ) with activated difluorodiphenylketone, dichlorodiphenylsulfone and both together. The (CO) polymers obtained have inherent viscosity of 0.20~0.70 dL/g and glass transition temperature (by DSC) in 250~264℃. These polymers have good thermooxidative stability with 5% mass loss temperature of 442~491℃ in air. They are readily soluble in chloroform, dimethylacetamide, pyridine etc and can be cast into transparent, tough films. The FT-IR and 1H NMR data were recorded.
A series of novel poly(aryl ether)s:poly(ether sulfone)(PPES), poly(ether ketone)(PPEK) and their copolymer poly(ether sulfone ketone)(PPESK) were synthesized at high temperature by nucleophilic polycondensation of bisphenol 4-(3-phenyl 4-hydroxyphenyl)-2,3-phthalazin-1-one(OP-DHPZ) with activated difluorodiphenylketone, dichlorodiphenylsulfone and both together. The (CO) polymers obtained have inherent viscosity of 0.20~0.70 dL/g and glass transition temperature (by DSC) in 250~264℃. These polymers have good thermooxidative stability with 5% mass loss temperature of 442~491℃ in air. They are readily soluble in chloroform, dimethylacetamide, pyridine etc and can be cast into transparent, tough films. The FT-IR and 1H NMR data were recorded.
2002, 19(3): 243-246
Abstract:
Eight Mannich bases were synthesized from reaction of formaldehyde and dimethylamine hydrochloride and substituted anilines, respectively with 2-ethoxycarbonyl cyclododecanone. Their structures were confirmed by IR 1H NMR and elemental analysis. Mannich reaction of an amine was occurred at 2nd position of 2-ethoxycarbonyl-cyclododecanone. The preliminary in vitro bioassys of some compounds indicated that some of compounds Ⅳ showed certain fungistatic activity against plant pathogens. 4-Br substituted phenyl aminomethyl-2-ethoxycarbonyl cyclododecanone exerted appreciable inhibitory effect on xylene-induced ear edema in mice.
Eight Mannich bases were synthesized from reaction of formaldehyde and dimethylamine hydrochloride and substituted anilines, respectively with 2-ethoxycarbonyl cyclododecanone. Their structures were confirmed by IR 1H NMR and elemental analysis. Mannich reaction of an amine was occurred at 2nd position of 2-ethoxycarbonyl-cyclododecanone. The preliminary in vitro bioassys of some compounds indicated that some of compounds Ⅳ showed certain fungistatic activity against plant pathogens. 4-Br substituted phenyl aminomethyl-2-ethoxycarbonyl cyclododecanone exerted appreciable inhibitory effect on xylene-induced ear edema in mice.
2002, 19(3): 247-250
Abstract:
The mesoporous molecular sieves M-HMS(M=Fe,Cu,Co,V) were synthesized by using dodecylamine as template and characterized by XRD, IR, ESR. The results revealed the incorporation of the transition metal ions in the HMS framework. It was found that catalytic activity of M HMS in hydroxylation of phenol by H2O2 was obviously higher than that of the supported catalysts, M/SiO2(M=Fe,Cu,Co,V) at the same reaction conditions. The active site of the M-HMS appeared the transition metal ion incorporated in HMS framework.
The mesoporous molecular sieves M-HMS(M=Fe,Cu,Co,V) were synthesized by using dodecylamine as template and characterized by XRD, IR, ESR. The results revealed the incorporation of the transition metal ions in the HMS framework. It was found that catalytic activity of M HMS in hydroxylation of phenol by H2O2 was obviously higher than that of the supported catalysts, M/SiO2(M=Fe,Cu,Co,V) at the same reaction conditions. The active site of the M-HMS appeared the transition metal ion incorporated in HMS framework.
2002, 19(3): 251-254
Abstract:
A diesel fuel additive has been synthesized from dimethyl ether(DME) by using dielectric-barrier discharging at atmospheric pressure and low temperature. A high conversion of DME has been obtained. The product is a mixture of dimethoxy-containing hydrocarbons with high cetane number, which can be used as a high efficienty diesel fuel additive. The results indicated that the length of discharge gap, reaction temperature and discharge power significantly affected the conversion of DME. At 120℃ and flow rate of DME 30 mL/min the maximum conversion of DME reached 47.20% with a selectivity of liquid product more than 39%.
A diesel fuel additive has been synthesized from dimethyl ether(DME) by using dielectric-barrier discharging at atmospheric pressure and low temperature. A high conversion of DME has been obtained. The product is a mixture of dimethoxy-containing hydrocarbons with high cetane number, which can be used as a high efficienty diesel fuel additive. The results indicated that the length of discharge gap, reaction temperature and discharge power significantly affected the conversion of DME. At 120℃ and flow rate of DME 30 mL/min the maximum conversion of DME reached 47.20% with a selectivity of liquid product more than 39%.
2002, 19(3): 255-258
Abstract:
A self assembled supermolecular film gold electrode has been fabricated from Keggin type phosphormolybdate anions and L-cysteine based on the electrostatic attraction between PMo12O403- and surface NH3+ of L-cysteine. Compared with PMo12O403-, the supermolecular film electrode is effective in a wider pH range and shows a good response to H+. The cyclic voltammetry and (ATR)FTIR techniques were used in the electrochemical characterization. The formation of the films and the pH sensor behavior have been discussed. The major properties of the pH film sensor have been demonstrated.
A self assembled supermolecular film gold electrode has been fabricated from Keggin type phosphormolybdate anions and L-cysteine based on the electrostatic attraction between PMo12O403- and surface NH3+ of L-cysteine. Compared with PMo12O403-, the supermolecular film electrode is effective in a wider pH range and shows a good response to H+. The cyclic voltammetry and (ATR)FTIR techniques were used in the electrochemical characterization. The formation of the films and the pH sensor behavior have been discussed. The major properties of the pH film sensor have been demonstrated.
2002, 19(3): 259-262
Abstract:
Eight (Z)-2-(1H-imidazole-1-yl)-1-(2,3,4-trimethoxy)acetophenoxime esters(Ⅳ) were prepared in 62.1%~84 1% yield by reacting (Z)-2-(1H-imidazole-1-yl)-1-(2,3,4-trimethoxy)acetophenoxime(Ⅲ) with acyl chloride in the presence of methylene dichloride and triethylamine. The structures of the new compounds were proved by means of elemental analysis, IR and 1H NMR spectrum data. The relationship between the configuration and the spectral character was discussed.
Eight (Z)-2-(1H-imidazole-1-yl)-1-(2,3,4-trimethoxy)acetophenoxime esters(Ⅳ) were prepared in 62.1%~84 1% yield by reacting (Z)-2-(1H-imidazole-1-yl)-1-(2,3,4-trimethoxy)acetophenoxime(Ⅲ) with acyl chloride in the presence of methylene dichloride and triethylamine. The structures of the new compounds were proved by means of elemental analysis, IR and 1H NMR spectrum data. The relationship between the configuration and the spectral character was discussed.
2002, 19(3): 263-266
Abstract:
The process of the formation of reversed micell in lithium di(2-ethylhexyl)phosphorate(P204Li) in organic phase has been studied using a microcalorimetric method. The thermal power-titration time curves for the formation of reversed micell were obtained. The critical micelle concentration (CMC), aggregation number(n), micelle formation constant(K) and thermodynamic functions(ΔrHm0,ΔrGm0,ΔrSm0) have been calculated.
The process of the formation of reversed micell in lithium di(2-ethylhexyl)phosphorate(P204Li) in organic phase has been studied using a microcalorimetric method. The thermal power-titration time curves for the formation of reversed micell were obtained. The critical micelle concentration (CMC), aggregation number(n), micelle formation constant(K) and thermodynamic functions(ΔrHm0,ΔrGm0,ΔrSm0) have been calculated.
2002, 19(3): 267-270
Abstract:
Solvent extraction of trace concentration of gold(Ⅰ) from alkaline cyanide solution by extractants, tetra decyldi methyl benzyl ammonium chloride(TDMBAC), primary amine N1923, tri-n-octylamine(TOA) has been carried out by using a 198Au radioactive tracer method. The influences of gold concentration, the molar ratio of extractant to Au(CN)2-, volume percentage of synergic reagent, phase volume ratio and salting-out agent have been studied. The results indicate that 198Au radioactive tracer method is a quick, convenient, accurate method especially for extraction of trace concentration of gold. When the molar ratio of TDMBAC to gold (0.1 mg/L) is more than 50, the extraction percentage reaches 95%. The extraction percentage does not change much with the further addition of synergic reagent TBP(tributyl phosphate) after its volume percentage reaches 20%. Salt has little effect on the gold extraction. Stripping extraction of gold from such loaded organic phases was also discussed.
Solvent extraction of trace concentration of gold(Ⅰ) from alkaline cyanide solution by extractants, tetra decyldi methyl benzyl ammonium chloride(TDMBAC), primary amine N1923, tri-n-octylamine(TOA) has been carried out by using a 198Au radioactive tracer method. The influences of gold concentration, the molar ratio of extractant to Au(CN)2-, volume percentage of synergic reagent, phase volume ratio and salting-out agent have been studied. The results indicate that 198Au radioactive tracer method is a quick, convenient, accurate method especially for extraction of trace concentration of gold. When the molar ratio of TDMBAC to gold (0.1 mg/L) is more than 50, the extraction percentage reaches 95%. The extraction percentage does not change much with the further addition of synergic reagent TBP(tributyl phosphate) after its volume percentage reaches 20%. Salt has little effect on the gold extraction. Stripping extraction of gold from such loaded organic phases was also discussed.
2002, 19(3): 271-275
Abstract:
The solid acid catalysts of SO42-/TiO2 and SO42-/ZrO2 and a series of SO42-/TiO2-ZrO2 catalysts have been prepared and characterized by XRD, FTIR and TG DTA. The regioselectivities of chlorobenzene in mononitration with these catalysts were investigated. It was found that chlorobenzene is nitrated with high para selectivity in the presence of acetic anhydride using the solid acid as catalyst and a stoichiometric quantity of nitric acid. Over SO42-/TiO2-ZrO2(atom ratio 1:2) catalyst, nitration of chlorobenzene gives a 70.2% yield of mononitro compounds, with an ortho para isomer ratio 0.29, greatly below 0.57 as sulfonitric acid as catalyst. The process is rapid, and the catalysts can be repeatedely used 4 times without reduction of ortho/para ratio of product.
The solid acid catalysts of SO42-/TiO2 and SO42-/ZrO2 and a series of SO42-/TiO2-ZrO2 catalysts have been prepared and characterized by XRD, FTIR and TG DTA. The regioselectivities of chlorobenzene in mononitration with these catalysts were investigated. It was found that chlorobenzene is nitrated with high para selectivity in the presence of acetic anhydride using the solid acid as catalyst and a stoichiometric quantity of nitric acid. Over SO42-/TiO2-ZrO2(atom ratio 1:2) catalyst, nitration of chlorobenzene gives a 70.2% yield of mononitro compounds, with an ortho para isomer ratio 0.29, greatly below 0.57 as sulfonitric acid as catalyst. The process is rapid, and the catalysts can be repeatedely used 4 times without reduction of ortho/para ratio of product.
2002, 19(3): 276-279
Abstract:
The N-nitrosamine content in smoke of different brand cigarettes has been examined as function of the content of tar and nicotine in cigarettes. The results show that the content of N-nitrosamine in the side-stream of burning cigarette gas was not seriously related to the content of tar or nicotine. Therefore it is inefficient to decrease tar content in the cigarette for absolute removal of N-nitrosamine from the smoke, even when the content of tar was lowered to 1 mg/per cigarette. A new way to remove N-nitrosamine from the smoke of cigarette is proposed based on the fact that N-nitrosamine can be selectively adsorbed and/or catalytic degraded by zeolites. The GC-MS results revealed the influence of adding manner of zeolite on the removal of N-nitrosamine from cigarette smoke. Much more carcinogenic compounds in the smoke could be adsorbed when the zeolite was dispersed in tobacco instead of putting in filter. About 30% of tobacco specific N-nitrosamine(TSNA) could be eliminated from side-stream, meanwhile 35%~61% of the TSNA disappeared in the main stream by use of zeolite-like materials such as NaY and NaZSM-5 additive in the tobacco. About 50% of the total amount of N-nitrosamine were found to be removed from the side stream of cigarette when the mass fraction of the additive was less than 5%. For the main stream, about 70% of the N-nitrosamine could be removed in the case of spraying zeolite on the tobacco.
The N-nitrosamine content in smoke of different brand cigarettes has been examined as function of the content of tar and nicotine in cigarettes. The results show that the content of N-nitrosamine in the side-stream of burning cigarette gas was not seriously related to the content of tar or nicotine. Therefore it is inefficient to decrease tar content in the cigarette for absolute removal of N-nitrosamine from the smoke, even when the content of tar was lowered to 1 mg/per cigarette. A new way to remove N-nitrosamine from the smoke of cigarette is proposed based on the fact that N-nitrosamine can be selectively adsorbed and/or catalytic degraded by zeolites. The GC-MS results revealed the influence of adding manner of zeolite on the removal of N-nitrosamine from cigarette smoke. Much more carcinogenic compounds in the smoke could be adsorbed when the zeolite was dispersed in tobacco instead of putting in filter. About 30% of tobacco specific N-nitrosamine(TSNA) could be eliminated from side-stream, meanwhile 35%~61% of the TSNA disappeared in the main stream by use of zeolite-like materials such as NaY and NaZSM-5 additive in the tobacco. About 50% of the total amount of N-nitrosamine were found to be removed from the side stream of cigarette when the mass fraction of the additive was less than 5%. For the main stream, about 70% of the N-nitrosamine could be removed in the case of spraying zeolite on the tobacco.
2002, 19(3): 280-284
Abstract:
The texture and surface morphology of Cu electrodeposited on stainless steel at different current densities from H2SO4+CuSO4 electrolyte solution under unstirring, mechanical agitation and air agitation condition have been studied by means of XRD and SEM technique. The results showed that the surface morphology and crystal orientation of Cu electrodeposits varied mainly with the current density used in deposition:at c.d.<6.0 A/dm2 (110) orientation was found to be favorable. When c.d.>15.0 A/dm2, (111) orientation was preferred, and no obvious crystal orientation was observed at medium current density. Increase in current densities made the Cu electro-crystallization varied from lateral to outward growth modes.
The texture and surface morphology of Cu electrodeposited on stainless steel at different current densities from H2SO4+CuSO4 electrolyte solution under unstirring, mechanical agitation and air agitation condition have been studied by means of XRD and SEM technique. The results showed that the surface morphology and crystal orientation of Cu electrodeposits varied mainly with the current density used in deposition:at c.d.<6.0 A/dm2 (110) orientation was found to be favorable. When c.d.>15.0 A/dm2, (111) orientation was preferred, and no obvious crystal orientation was observed at medium current density. Increase in current densities made the Cu electro-crystallization varied from lateral to outward growth modes.
2002, 19(3): 285-289
Abstract:
Microperoxidase-11(MP-11) was adsorbed on active carbon by equilibrium adsorption method. The electrocatalytic behaviors of MP-11/C electrode for the reduction of O2 and H2O2 were studied by cyclic voltammmetry and linear voltammmetry and RDE technique. The results showed that MP-11/C possessed good electrocatalytic activity for the reduction of O2 and H2O2. And the mechanism of oxygen reduction is dependent on pH of the solution. It provides a reliable method for immobilization of enzymes and a promising catalyst for the reduction of O2 in biofuel cell.
Microperoxidase-11(MP-11) was adsorbed on active carbon by equilibrium adsorption method. The electrocatalytic behaviors of MP-11/C electrode for the reduction of O2 and H2O2 were studied by cyclic voltammmetry and linear voltammmetry and RDE technique. The results showed that MP-11/C possessed good electrocatalytic activity for the reduction of O2 and H2O2. And the mechanism of oxygen reduction is dependent on pH of the solution. It provides a reliable method for immobilization of enzymes and a promising catalyst for the reduction of O2 in biofuel cell.
2002, 19(3): 290-294
Abstract:
The V2O5/γ-Al2O3 for dehydrogenation of isobutane was found to have a high catalytic activity under reaction conditions of 590℃, GHSV=1 000 h-1 and atmospheric pressure. The structure of the catalyst was characterized by means of XRD, UV-V is and BET technique. The results indicated that the dehydrogenation behavior of the catalyst was in correlation with the dispersion and the state of vanadia on the catalyst surface. Chemical composition and physical state of vanadia on the catalyst surface are affected by the kind of support, the loading of vanadium and calcination temperature as well.
The V2O5/γ-Al2O3 for dehydrogenation of isobutane was found to have a high catalytic activity under reaction conditions of 590℃, GHSV=1 000 h-1 and atmospheric pressure. The structure of the catalyst was characterized by means of XRD, UV-V is and BET technique. The results indicated that the dehydrogenation behavior of the catalyst was in correlation with the dispersion and the state of vanadia on the catalyst surface. Chemical composition and physical state of vanadia on the catalyst surface are affected by the kind of support, the loading of vanadium and calcination temperature as well.
2002, 19(3): 295-297
Abstract:
Some N-pivot crown ether dithiocarbamate complexes with transition metal have been prepared and characterized by chemical analysis as well as spectral and magnetic measurements. All the complexes were found to be stable in air and their molar conductances in dimethylformamide solution were ranged in 2.74~9.03 S·cm2/mol, indicating that they are non-electrolytes. The results showed that the dithiocarbamate groups act as bidentate in these complexes.
Some N-pivot crown ether dithiocarbamate complexes with transition metal have been prepared and characterized by chemical analysis as well as spectral and magnetic measurements. All the complexes were found to be stable in air and their molar conductances in dimethylformamide solution were ranged in 2.74~9.03 S·cm2/mol, indicating that they are non-electrolytes. The results showed that the dithiocarbamate groups act as bidentate in these complexes.
2002, 19(3): 298-300
Abstract:
Cellulose xanthates(CX) were prepared by xanthation of alkali straw cellulose. The removing of Cu2+, Cd2+, Co2+ and Ni2+ from zinc sulphate solutions by CX has been investigated as function of pH of solution, xanthate dosage, reaction time and temperature. The results show that when removing was carried out in 2 steps under the conditions pH=of 5.0~5.2 and 5.2~5.4, reaction time of 90 and 120 min and at 55℃ and 65℃, the contents of Cu2+, Cd2+, Co2+ and Ni2+ can be reduced from 270.8, 962.0, 14.22 and 10.64 mg/L to 0.12, 0.58, 0.44 and 0.52 mg/L respectively2+ The total loss of zinc ion in the solution was less 1%(mass fraction).
Cellulose xanthates(CX) were prepared by xanthation of alkali straw cellulose. The removing of Cu2+, Cd2+, Co2+ and Ni2+ from zinc sulphate solutions by CX has been investigated as function of pH of solution, xanthate dosage, reaction time and temperature. The results show that when removing was carried out in 2 steps under the conditions pH=of 5.0~5.2 and 5.2~5.4, reaction time of 90 and 120 min and at 55℃ and 65℃, the contents of Cu2+, Cd2+, Co2+ and Ni2+ can be reduced from 270.8, 962.0, 14.22 and 10.64 mg/L to 0.12, 0.58, 0.44 and 0.52 mg/L respectively2+ The total loss of zinc ion in the solution was less 1%(mass fraction).
2002, 19(3): 301-303
Abstract:
A chemical analytical method for quantitative determination in hydroxyethyl group of hydroxyethyl-U-cyclodextrin is proposed. The method consists of reacting hydroxyethyl-U-cyclodextrin with HI in the presence of catalyst on heating to form the corresponding amounts of ethene and iodoethane. Then react these compounds with bromine to give I 2, which can be easily determined by standard hyposulphite solution. The formulas for calculation of the average substitution degree from titration results are described. The results obtained by this method appeared to be more accurate than those based on 1H NMR method.
A chemical analytical method for quantitative determination in hydroxyethyl group of hydroxyethyl-U-cyclodextrin is proposed. The method consists of reacting hydroxyethyl-U-cyclodextrin with HI in the presence of catalyst on heating to form the corresponding amounts of ethene and iodoethane. Then react these compounds with bromine to give I 2, which can be easily determined by standard hyposulphite solution. The formulas for calculation of the average substitution degree from titration results are described. The results obtained by this method appeared to be more accurate than those based on 1H NMR method.
2002, 19(3): 304-306
Abstract:
(R)-and (S)-(2-benzyloxyethyl)oxirane 1 were prepared from (S) and (R) aspartic acid by modification of the procedure described by Rapoport. Aspartic acid was converted into bromosuccinic acid 2 by treatment with sodium nitrite/potassium bromide/sulfuric acid,the diacid 2 was then reduced with freshly prepared boron trifluoride ethyl ether complex to bromodiol 3, which was further treated with sodium hydride and benzylbromide/TBAI(tetrabutylammonium iodide) to afford (2-benzyloxyethyl)oxirane. This procedure has shown the good yield, mild condition and excellent enantiomeric purity of the product.
(R)-and (S)-(2-benzyloxyethyl)oxirane 1 were prepared from (S) and (R) aspartic acid by modification of the procedure described by Rapoport. Aspartic acid was converted into bromosuccinic acid 2 by treatment with sodium nitrite/potassium bromide/sulfuric acid,the diacid 2 was then reduced with freshly prepared boron trifluoride ethyl ether complex to bromodiol 3, which was further treated with sodium hydride and benzylbromide/TBAI(tetrabutylammonium iodide) to afford (2-benzyloxyethyl)oxirane. This procedure has shown the good yield, mild condition and excellent enantiomeric purity of the product.
