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2005 Volume 22 Issue 12
2005, 22(12): 1277-1281
Abstract:
The recent development in research on cathodic catalysts for direct methanol fuel cells(DMFC) is reviewed.At present,the cathodic catalyst used in DMFC is usually Pt.Its main problems are low electrocatalytic activity for oxygen reduction and performance degradation due to methanol penetrating through the proton exchange membrane.The addition of Cr,Ni,heteropolyacids,or porphyrin and phthalocyanion of the transition metals to the Pt catalyst can increase not only the electrocatalytic activity of the Pt for the oxygen reduction,but also the methanol tolerance of the Pt.Therefore,these Pt-based composite catalysts are in prospect of being used as the cathodic catalyst in DMFC.
The recent development in research on cathodic catalysts for direct methanol fuel cells(DMFC) is reviewed.At present,the cathodic catalyst used in DMFC is usually Pt.Its main problems are low electrocatalytic activity for oxygen reduction and performance degradation due to methanol penetrating through the proton exchange membrane.The addition of Cr,Ni,heteropolyacids,or porphyrin and phthalocyanion of the transition metals to the Pt catalyst can increase not only the electrocatalytic activity of the Pt for the oxygen reduction,but also the methanol tolerance of the Pt.Therefore,these Pt-based composite catalysts are in prospect of being used as the cathodic catalyst in DMFC.
2005, 22(12): 1282-1286
Abstract:
MAH grafted polyethylene was prepared by means of in-situ reaction of HDPE in solid state with chlorine and MAH simultaneously.FTIR and 1H NMR were used to verify the formation of the target copolymer and to characterize its chemical structure.A quantitative method was developed to(measure) the grafting degree of MAH by virtue of chemical titration and FTIR.The prepared copolymer had a higher grafting degree(up to 2.6% by mass) compared to the MAH grafted PE by conventional methods,and was not crosslinked as proved via the determination of the gel percentage of the grafted samples.
MAH grafted polyethylene was prepared by means of in-situ reaction of HDPE in solid state with chlorine and MAH simultaneously.FTIR and 1H NMR were used to verify the formation of the target copolymer and to characterize its chemical structure.A quantitative method was developed to(measure) the grafting degree of MAH by virtue of chemical titration and FTIR.The prepared copolymer had a higher grafting degree(up to 2.6% by mass) compared to the MAH grafted PE by conventional methods,and was not crosslinked as proved via the determination of the gel percentage of the grafted samples.
2005, 22(12): 1287-1290
Abstract:
Two new polyorganophosphazenes containing carbazolyl side groups were obtained from poly(dichlorophosphazene) via nucleophilic substitution reaction.The chemical structures of these polymers were characterized by IR,1H NMR,31P NMR and UV-Vis.The results demonstrate that the substitution of the chlorine by the carbazolyl group was complete,and the UV-vis absorption maximum of the polymer was consistent with that of carbazolyl group.GPC results show that the molecular weights of these polymers are 34 700 and 11 300,respectively.The DSC results indicate that the two amorphous polyphosphazenes exhibit low glass transition temperatures,and they begin to decompose at around 300℃.
Two new polyorganophosphazenes containing carbazolyl side groups were obtained from poly(dichlorophosphazene) via nucleophilic substitution reaction.The chemical structures of these polymers were characterized by IR,1H NMR,31P NMR and UV-Vis.The results demonstrate that the substitution of the chlorine by the carbazolyl group was complete,and the UV-vis absorption maximum of the polymer was consistent with that of carbazolyl group.GPC results show that the molecular weights of these polymers are 34 700 and 11 300,respectively.The DSC results indicate that the two amorphous polyphosphazenes exhibit low glass transition temperatures,and they begin to decompose at around 300℃.
2005, 22(12): 1291-1294
Abstract:
Co nanorods with hexagonal structure were prepared by means of the reduction method with the aid of microwave.Different surfactants were used to modify the surfaces of the Co nanorods.The radius and the length of the Co nanorods were about 20 nm and 100 nm respectively observed by transmission electron microscopy and laser light scattering.The Co nanorods showed narrow size distribution and no agglomeration in hexane.The surface-valence of the cobalt nanorods was determined to be zero by XPS.
Co nanorods with hexagonal structure were prepared by means of the reduction method with the aid of microwave.Different surfactants were used to modify the surfaces of the Co nanorods.The radius and the length of the Co nanorods were about 20 nm and 100 nm respectively observed by transmission electron microscopy and laser light scattering.The Co nanorods showed narrow size distribution and no agglomeration in hexane.The surface-valence of the cobalt nanorods was determined to be zero by XPS.
2005, 22(12): 1295-1299
Abstract:
Emulsifier-free poly(styrene-methylmethacrylate)(P(St-MMA)) copolymer nanoparticles with an average diameter of about 31 nm were synthesized in an acetone-water medium with potassium persulfate(KPS) as the initiator by solvothermal method.The effects of amount of acetone,MMA/St ratio,the concentration of KPS and temperature on the polymerization rate,the particle size and the size distribution as well as the stability of the latex were investigated systematically.The results indicate that with increasing temperature,the particle size decreases first,and then increases and reaches a minimum at 90℃;with increasing the volume fraction of acetone or the volume ratio of MMA to St,the particle size decreases from 267 nm to 34 nm and the electrolyte-resistance stability of the latex increases;the polymerization rate in the last reaction stage falls down on increasing the volume fraction of acetone;with increasing the KPS concentration,the particle size decreases first and then increases.The solvothermal mothod has offered a new route to emulsifer-free macromolecule nanoparticles.
Emulsifier-free poly(styrene-methylmethacrylate)(P(St-MMA)) copolymer nanoparticles with an average diameter of about 31 nm were synthesized in an acetone-water medium with potassium persulfate(KPS) as the initiator by solvothermal method.The effects of amount of acetone,MMA/St ratio,the concentration of KPS and temperature on the polymerization rate,the particle size and the size distribution as well as the stability of the latex were investigated systematically.The results indicate that with increasing temperature,the particle size decreases first,and then increases and reaches a minimum at 90℃;with increasing the volume fraction of acetone or the volume ratio of MMA to St,the particle size decreases from 267 nm to 34 nm and the electrolyte-resistance stability of the latex increases;the polymerization rate in the last reaction stage falls down on increasing the volume fraction of acetone;with increasing the KPS concentration,the particle size decreases first and then increases.The solvothermal mothod has offered a new route to emulsifer-free macromolecule nanoparticles.
2005, 22(12): 1300-1303
Abstract:
HClO was produced from NaClO or Ca(ClO)2 under acidic condition,and organic compounds in wastewater were degraded via Fenton reaction with HClO instead of H2O2.Experimental results indicate that the reduction of chemical oxygen demand(COD) were 40%,38%,12%,50%,and 73% for β-naphthol,salt R a intermediate of dye,dihydroxy salt R,acid red (dye),and wastewater,respectively when the reactions had run for 4 h at a pH of 1.7.In comparison,the COD reduction of β-naphthol and salt R were 10.2% and 16.2%,lower than 23.4% and 18.1% with H2O2,while the Fenton reaction time was 1 h.However,under UV light,the corresponding COD reduction rates were 35.0% and 23.1% with HClO vs 29.8% and 21.3% with H2O2.These results show that it is feasible to use HClO instead of H2O2 in Fenton reaction.
HClO was produced from NaClO or Ca(ClO)2 under acidic condition,and organic compounds in wastewater were degraded via Fenton reaction with HClO instead of H2O2.Experimental results indicate that the reduction of chemical oxygen demand(COD) were 40%,38%,12%,50%,and 73% for β-naphthol,salt R a intermediate of dye,dihydroxy salt R,acid red (dye),and wastewater,respectively when the reactions had run for 4 h at a pH of 1.7.In comparison,the COD reduction of β-naphthol and salt R were 10.2% and 16.2%,lower than 23.4% and 18.1% with H2O2,while the Fenton reaction time was 1 h.However,under UV light,the corresponding COD reduction rates were 35.0% and 23.1% with HClO vs 29.8% and 21.3% with H2O2.These results show that it is feasible to use HClO instead of H2O2 in Fenton reaction.
2005, 22(12): 1304-1307
Abstract:
In the medium of NaOH-EDTA,cationic surfactant tetradecylmethylbenzylammonium chloride,(TDMBA),associaues with proteins,such as human serum albumin(HSA), bovine serum albumin(BSA),γ-globulin(γ-G) and ovalbumin(Ova),to form associated particles,which enhances the resonance scattering.There were 5 resonance scattering peaks at 340,400,420,470,and 520 nm,respectively,and the strongest one was at 470 nm after TDMBA was added to the HSA system.When the HSA association system was excited by the light at 280 nm,it exhibited a strong fluorescence peak at 470nm,while the fluorescence peak at 330 nm quenched with the addition of the associated particles.Under proper experimental conditions,the protein determination can be performed in the range of 0.168.0 mg/L for HSA,0.0816.0 mg/L for BSA,0.1616.0 mg/L for γ-G,and 0.660.0 mg/L for Ova.The detection limits are 0.01,0.01,0.01,0.06 mg/L for HSA,BSA,γ-G,and Ova respectively.This method was applied to the determination of the total proteins in human serum with satisfactory results.
In the medium of NaOH-EDTA,cationic surfactant tetradecylmethylbenzylammonium chloride,(TDMBA),associaues with proteins,such as human serum albumin(HSA), bovine serum albumin(BSA),γ-globulin(γ-G) and ovalbumin(Ova),to form associated particles,which enhances the resonance scattering.There were 5 resonance scattering peaks at 340,400,420,470,and 520 nm,respectively,and the strongest one was at 470 nm after TDMBA was added to the HSA system.When the HSA association system was excited by the light at 280 nm,it exhibited a strong fluorescence peak at 470nm,while the fluorescence peak at 330 nm quenched with the addition of the associated particles.Under proper experimental conditions,the protein determination can be performed in the range of 0.168.0 mg/L for HSA,0.0816.0 mg/L for BSA,0.1616.0 mg/L for γ-G,and 0.660.0 mg/L for Ova.The detection limits are 0.01,0.01,0.01,0.06 mg/L for HSA,BSA,γ-G,and Ova respectively.This method was applied to the determination of the total proteins in human serum with satisfactory results.
2005, 22(12): 1308-1311
Abstract:
To select a suitable decolorizing resin for crude Saposhnikovia divaricata polysaccharide(SPS),with both the decolorization ratio and the carbohydrate reservation ratio as the indexes,the decolorization effect of crude SPS by eight different resins were studied.The results show that the order of their decolorization ratios is:D280 > D392 > 201×4 > D3520 > 201×7 > NKA-Ⅱ > NKA-9 > 001×7,and the column capacity of D280 is higher than that of D392.At their optimal loading,which is 1.2 g crude SPS per 30 g wet resin,the decolorization ratios and carbohydrate reservation ratios are 84.3%,76.4% and 80.6%,82.7%,respec-tively.The above results show that macroporous anion exchange resins are suitable for the decolorization of crude SPS.
To select a suitable decolorizing resin for crude Saposhnikovia divaricata polysaccharide(SPS),with both the decolorization ratio and the carbohydrate reservation ratio as the indexes,the decolorization effect of crude SPS by eight different resins were studied.The results show that the order of their decolorization ratios is:D280 > D392 > 201×4 > D3520 > 201×7 > NKA-Ⅱ > NKA-9 > 001×7,and the column capacity of D280 is higher than that of D392.At their optimal loading,which is 1.2 g crude SPS per 30 g wet resin,the decolorization ratios and carbohydrate reservation ratios are 84.3%,76.4% and 80.6%,82.7%,respec-tively.The above results show that macroporous anion exchange resins are suitable for the decolorization of crude SPS.
2005, 22(12): 1312-1315
Abstract:
The influence of β-cyclodextrin(β-CD) on the photocatalytic decolorization of methyl orange solution under ultraviolet irradiation was studied by UV-Vis spectral analysis.The photocatalytic decolorization rate of the methyl orange solution was found to decrease with the addition of β-CD.The suppression of the methyl orange decolorization by β-CD was significant at pH 610,and maximized at pH=8.At 3 h irradiation,the decolorization rate of a 5×10-5 mol/L methyl orange solution containing 4×10-4 mol/L β-CD was 3/5 that of a blank methyl orange solution.
The influence of β-cyclodextrin(β-CD) on the photocatalytic decolorization of methyl orange solution under ultraviolet irradiation was studied by UV-Vis spectral analysis.The photocatalytic decolorization rate of the methyl orange solution was found to decrease with the addition of β-CD.The suppression of the methyl orange decolorization by β-CD was significant at pH 610,and maximized at pH=8.At 3 h irradiation,the decolorization rate of a 5×10-5 mol/L methyl orange solution containing 4×10-4 mol/L β-CD was 3/5 that of a blank methyl orange solution.
2005, 22(12): 1316-1319
Abstract:
Three 3,4-dihydroxy-2,5-bis(2'-(4'-substitutedoxazolinyl))furans were synthesized in yields of(90%~94%) from 3,4-dihydroxy-2,5-furan dicarboxylic acid or its dimethyl ester with chiral β-amino alcohol via a one-step reaction,and their chemical structures were determined by 1H NMR,IR,MS,and elemental analysis.With these chiral bisoxazoline ligands,the asymmetric reduction of β-acetonaphthalene by KBH4 or NaBH4 was preliminarily studied.The enantiomeric excess of the reduction product was up to 83.2% using cyclohexane as the solvent,n(ligand):n(reductive agent):n(β-acetonaphthalene)=0.04:1.6:1,and 72 h reaction time at 0℃,and furan-containing bisoxazoline with 4-benzyl on oxazoline rings exhibited higher enantioselectivity than congeneric bisoxazolines with 4-ethyl on oxazoline rings.
Three 3,4-dihydroxy-2,5-bis(2'-(4'-substitutedoxazolinyl))furans were synthesized in yields of(90%~94%) from 3,4-dihydroxy-2,5-furan dicarboxylic acid or its dimethyl ester with chiral β-amino alcohol via a one-step reaction,and their chemical structures were determined by 1H NMR,IR,MS,and elemental analysis.With these chiral bisoxazoline ligands,the asymmetric reduction of β-acetonaphthalene by KBH4 or NaBH4 was preliminarily studied.The enantiomeric excess of the reduction product was up to 83.2% using cyclohexane as the solvent,n(ligand):n(reductive agent):n(β-acetonaphthalene)=0.04:1.6:1,and 72 h reaction time at 0℃,and furan-containing bisoxazoline with 4-benzyl on oxazoline rings exhibited higher enantioselectivity than congeneric bisoxazolines with 4-ethyl on oxazoline rings.
2005, 22(12): 1320-1323
Abstract:
Condensations of 4-methylbenzoyl hydrazine(1) with aromatic aldehydes produced corresponding hydrazones(2a~2k).Cyclization of hydrazones 2a~2k with propanoic anhydide gave the title compounds 3a~3k in good yields of 70%~84%.Their structures were confirmed by means of elemental analysis,IR,1H NMR and MS spectrometry.
Condensations of 4-methylbenzoyl hydrazine(1) with aromatic aldehydes produced corresponding hydrazones(2a~2k).Cyclization of hydrazones 2a~2k with propanoic anhydide gave the title compounds 3a~3k in good yields of 70%~84%.Their structures were confirmed by means of elemental analysis,IR,1H NMR and MS spectrometry.
2005, 22(12): 1324-1328
Abstract:
A Dawson-type heteropolycompound[4,4-'bipyH]2H4(P2W18O62)·[4,4-'bipy]1.5·4H2O has been synthesized hydrothermally and characterized by means of IR,UV and X-ray single-crystal diffraction methods.X-ray crystal structural analysis indicates that the title compound crystals are triclinic with a space group Pī,and the lattice parameters are as follows:a=1.324 8(3) nm,b=1.411 9(3) nm,c=(2.683 3(5) nm),α=78.51(3) °,β=83.72(3) °,γ=68.07(3) °,V=4.559 4(16) nm3,Z=2,Dc=3.634 g/cm3,R1=0.055 3,wR2=0.129 0.The title compound consists of 2 protonated 4,4'-bipy molecules,0.5 discrete 4,4'-bipy molecule,4 H+ cations,1 heteropolyanion of[P2W18O62]6- and 4 water molecules
A Dawson-type heteropolycompound[4,4-'bipyH]2H4(P2W18O62)·[4,4-'bipy]1.5·4H2O has been synthesized hydrothermally and characterized by means of IR,UV and X-ray single-crystal diffraction methods.X-ray crystal structural analysis indicates that the title compound crystals are triclinic with a space group Pī,and the lattice parameters are as follows:a=1.324 8(3) nm,b=1.411 9(3) nm,c=(2.683 3(5) nm),α=78.51(3) °,β=83.72(3) °,γ=68.07(3) °,V=4.559 4(16) nm3,Z=2,Dc=3.634 g/cm3,R1=0.055 3,wR2=0.129 0.The title compound consists of 2 protonated 4,4'-bipy molecules,0.5 discrete 4,4'-bipy molecule,4 H+ cations,1 heteropolyanion of[P2W18O62]6- and 4 water molecules
2005, 22(12): 1329-1332
Abstract:
Nanoparticles of ferric oxide prepared by traditional methods are easy to aggregate in water phase,which leads to a decrease in its catalytic activity.To solve the problem,nanoparticles of ferric oxide were(prepared) in an oil-water two-phase system.To prepare the microemulsion,dodecylbenzenesulfonic acid sodium(DBS),methylbenzene,and butanol were respectively used as surfacetant(S),oil phase(O),and consurfactant(A).The conductivity measurement results showed that dodecylbenzenesulfonic acid sodium microemulsion had the largest solubilization when V(A)/V(O)=0.25,and m(A)/m(S)=1.50,and the extraction rate of Fe(OH)3 from the water phase into the oil phase is near 100% at pH=2.0~2.8.TG-DTA,XRD,H2-TPR,FT-IR,and particle size analysis were used to characterize their microstructure,and the amorphous nanoparticles(17.1 nm) of Fe2O3 were found to exhibit a narrow size distribution.The H2-TPR reduction peak temperature was siginificantly lower than that of the common ferric oxide.The major component of the powder usher was FeOOH,which was converted into Fe3O4 and finally into Fe2O3 with the increase of the calcination temperature,but aggregation phenomenon became evident when the temperature was increased further,and the best calcination temperature was 400℃.
Nanoparticles of ferric oxide prepared by traditional methods are easy to aggregate in water phase,which leads to a decrease in its catalytic activity.To solve the problem,nanoparticles of ferric oxide were(prepared) in an oil-water two-phase system.To prepare the microemulsion,dodecylbenzenesulfonic acid sodium(DBS),methylbenzene,and butanol were respectively used as surfacetant(S),oil phase(O),and consurfactant(A).The conductivity measurement results showed that dodecylbenzenesulfonic acid sodium microemulsion had the largest solubilization when V(A)/V(O)=0.25,and m(A)/m(S)=1.50,and the extraction rate of Fe(OH)3 from the water phase into the oil phase is near 100% at pH=2.0~2.8.TG-DTA,XRD,H2-TPR,FT-IR,and particle size analysis were used to characterize their microstructure,and the amorphous nanoparticles(17.1 nm) of Fe2O3 were found to exhibit a narrow size distribution.The H2-TPR reduction peak temperature was siginificantly lower than that of the common ferric oxide.The major component of the powder usher was FeOOH,which was converted into Fe3O4 and finally into Fe2O3 with the increase of the calcination temperature,but aggregation phenomenon became evident when the temperature was increased further,and the best calcination temperature was 400℃.
2005, 22(12): 1333-1337
Abstract:
The morphology of cured epoxy resin/imidazole system toughened by terminal functional liquid rubber has been investigated via SEM and TEM techniques.The presence of a tow-phase micro-structure was observed in modified cured systems in which the rubber micro-phase distributed in island form in the conti-nuous phase of the epoxy resin network.In fact,only when the domain size of the rubber phase is 1~3 μm,may the toughening result be optimum.The critical fracture energy release rate(GIC) could be improved more than ten times,and the tensile strength increases by 2~3 times,and the impact strength nearly doubles,when the DEGBA/imidazole cured system is toughened by CTBN at optimum level.The dynamic mechanical analysis indicated that the glass transformation temperature(Tg) of the cured system toughened by CTBN was reduced,because the CTBN cured imperfectly or dissolved incompletely in the modified cured system and plastisized the matrix.
The morphology of cured epoxy resin/imidazole system toughened by terminal functional liquid rubber has been investigated via SEM and TEM techniques.The presence of a tow-phase micro-structure was observed in modified cured systems in which the rubber micro-phase distributed in island form in the conti-nuous phase of the epoxy resin network.In fact,only when the domain size of the rubber phase is 1~3 μm,may the toughening result be optimum.The critical fracture energy release rate(GIC) could be improved more than ten times,and the tensile strength increases by 2~3 times,and the impact strength nearly doubles,when the DEGBA/imidazole cured system is toughened by CTBN at optimum level.The dynamic mechanical analysis indicated that the glass transformation temperature(Tg) of the cured system toughened by CTBN was reduced,because the CTBN cured imperfectly or dissolved incompletely in the modified cured system and plastisized the matrix.
2005, 22(12): 1338-1341
Abstract:
3-Methyl-4-nitrobenzoic acid was synthesized via oxidation of 2,4-dimethylnitrobenzene with mole-cular oxygen catalyzed by cobalt acetate in acetic acid in the presence of an initiator.It was found that the yield of 3-methyl-4-nitrobenzoic acid increased remarkably with the addition of sodium bromide as a co-catalyst.The reaction was carried out at 130℃ for 8 h at 0.8 MPa of oxygen in the presence of 0.017 mol of cobalt acetate,0.017 mol of sodium bromide,and 0.30 mol of 2-butanone with 1.00 mole of 2,4-dimethylnitrobenzene.Under these conditions 99% of the reactant converted with a selectivity of 52% to 3-methyl-4-nitrobenzoic acid,and the yield of 3-methyl-4-nitrobenzoic acid was 51%.The reaction mechanism and the function of sodium bromide were discussed.According to the fact that the reaction could not proceed without the presence of an initiator,it was proposed that the reaction took place via a free radical mechanism,and sodium bromide reacted with Co(Ⅲ) to generate bromine radicals,which promoted the formation of benzyl radicals.
3-Methyl-4-nitrobenzoic acid was synthesized via oxidation of 2,4-dimethylnitrobenzene with mole-cular oxygen catalyzed by cobalt acetate in acetic acid in the presence of an initiator.It was found that the yield of 3-methyl-4-nitrobenzoic acid increased remarkably with the addition of sodium bromide as a co-catalyst.The reaction was carried out at 130℃ for 8 h at 0.8 MPa of oxygen in the presence of 0.017 mol of cobalt acetate,0.017 mol of sodium bromide,and 0.30 mol of 2-butanone with 1.00 mole of 2,4-dimethylnitrobenzene.Under these conditions 99% of the reactant converted with a selectivity of 52% to 3-methyl-4-nitrobenzoic acid,and the yield of 3-methyl-4-nitrobenzoic acid was 51%.The reaction mechanism and the function of sodium bromide were discussed.According to the fact that the reaction could not proceed without the presence of an initiator,it was proposed that the reaction took place via a free radical mechanism,and sodium bromide reacted with Co(Ⅲ) to generate bromine radicals,which promoted the formation of benzyl radicals.
2005, 22(12): 1342-1346
Abstract:
Eu3+-activated yttrium oxysulfide red afterglow phosphor was synthesized by solid-state reaction and analyzed by means of XRD,SEM,and its emmision spectra(ES),relative brightness,and fluorescent(decay) were studied.Effects of firing conditions and flux on the crystal structure,particle size and morphology,and luminescent properties of the phosphor were studied.According to the results,the phosphor was obtained without any Y2O3 phase and exhibited well-formed crystalline particles.Luminescent properties can be optimized by well-formed crystalline particles.The corresponding firing condition is 1 150℃ in a weak reducing atmosphere.The addition of Li3PO4 helps to increase the mean diameter of the phosphor product and minimize the particle size distribution.
Eu3+-activated yttrium oxysulfide red afterglow phosphor was synthesized by solid-state reaction and analyzed by means of XRD,SEM,and its emmision spectra(ES),relative brightness,and fluorescent(decay) were studied.Effects of firing conditions and flux on the crystal structure,particle size and morphology,and luminescent properties of the phosphor were studied.According to the results,the phosphor was obtained without any Y2O3 phase and exhibited well-formed crystalline particles.Luminescent properties can be optimized by well-formed crystalline particles.The corresponding firing condition is 1 150℃ in a weak reducing atmosphere.The addition of Li3PO4 helps to increase the mean diameter of the phosphor product and minimize the particle size distribution.
2005, 22(12): 1347-1350
Abstract:
Sodium D-isoascorbate was synthesized from 2-keto-D-giucal and methanol using solid super acid SO42-/SiO2-TiO2 as a catalyst via an esterification process,in which the water formed was removed by fraction distillation.The performance of SO42-/SiO2-TiO2 and H2SO4 catalysts was compared.The optimum reaction conditions were found as follows:m(2-KGA):m(SO42-/SiO2-TiO2)=1:0.025,calcination temperature of the catalyst 550℃,reaction time 3~4 h,and the yield of the esterification was 88.6%.The solid super acid catalyst can be reused.
Sodium D-isoascorbate was synthesized from 2-keto-D-giucal and methanol using solid super acid SO42-/SiO2-TiO2 as a catalyst via an esterification process,in which the water formed was removed by fraction distillation.The performance of SO42-/SiO2-TiO2 and H2SO4 catalysts was compared.The optimum reaction conditions were found as follows:m(2-KGA):m(SO42-/SiO2-TiO2)=1:0.025,calcination temperature of the catalyst 550℃,reaction time 3~4 h,and the yield of the esterification was 88.6%.The solid super acid catalyst can be reused.
2005, 22(12): 1351-1353
Abstract:
Seven new N-(4-aminoantipyrine)-N'-aryloxyaceyl thioureas were synthesized.Their structures were confirmed by 1H NMR,IR and elemental analysis.The biological activity tests show that some target compounds have good activity as plant growth regulators,in particular N-(4-aminoantipyrine)-N'-o-(nitroaryloxyacetylthiourea) has an excellent cytokinin activity of 44.1%,which approaches the cytokinin activity of 6-furylmethylamino purine,which is 45.4%.
Seven new N-(4-aminoantipyrine)-N'-aryloxyaceyl thioureas were synthesized.Their structures were confirmed by 1H NMR,IR and elemental analysis.The biological activity tests show that some target compounds have good activity as plant growth regulators,in particular N-(4-aminoantipyrine)-N'-o-(nitroaryloxyacetylthiourea) has an excellent cytokinin activity of 44.1%,which approaches the cytokinin activity of 6-furylmethylamino purine,which is 45.4%.
2005, 22(12): 1354-1356
Abstract:
In an attempt to search for novel compounds with agricultural bioactivity,a series of new polysubstituted pyridine derivatives,α-[2-methyl-5-cyano4-(furan-2-yl)-3-ethoxycarboxyl-pyridine-6-thio]acetamide 4a, 2-methyl-5-cyano-4-(furan-2-yl)-3-acetyl pyridine-6-thioethers 5 and 6a were designed and synthesized by a three-step or one-step synthetic route.The structures of all the compounds prepared were confirmed by elemental analysis and 1H NMR.The preliminary bioassay results indicate that compound 4a possesses certain fungicidal and herbicidal activities.
In an attempt to search for novel compounds with agricultural bioactivity,a series of new polysubstituted pyridine derivatives,α-[2-methyl-5-cyano4-(furan-2-yl)-3-ethoxycarboxyl-pyridine-6-thio]acetamide 4a, 2-methyl-5-cyano-4-(furan-2-yl)-3-acetyl pyridine-6-thioethers 5 and 6a were designed and synthesized by a three-step or one-step synthetic route.The structures of all the compounds prepared were confirmed by elemental analysis and 1H NMR.The preliminary bioassay results indicate that compound 4a possesses certain fungicidal and herbicidal activities.
2005, 22(12): 1357-1359
Abstract:
N-alkyl chitosan was prepared by reducing a schiff base formed from chitosan and lauraldehyde,and microwave irradiation was applied to the preparation of N-alkyl chitosan.The effects of microwave power,irradiation time,amount of catalyst,and n(chitosan)/n(aldhyde) ratio on the degree of alkylation substitution of chitosan were studied.The modified chitosan was characterized by FTIR and EA.The substitution degree of the modified chitosan can reach 94% under the following reaction conditions:560 W microwave power,3 min reaction time,reactant ratio(n(chitosan)/n(lauraldehyde)) of 1:2.6,and molar ratio of SDS to lauraldehyde being 0.15:1. Compared to ordinary reactions,the preparation of N-alkyl chitosan by microwave irradiation can be finished within very short reaction time.
N-alkyl chitosan was prepared by reducing a schiff base formed from chitosan and lauraldehyde,and microwave irradiation was applied to the preparation of N-alkyl chitosan.The effects of microwave power,irradiation time,amount of catalyst,and n(chitosan)/n(aldhyde) ratio on the degree of alkylation substitution of chitosan were studied.The modified chitosan was characterized by FTIR and EA.The substitution degree of the modified chitosan can reach 94% under the following reaction conditions:560 W microwave power,3 min reaction time,reactant ratio(n(chitosan)/n(lauraldehyde)) of 1:2.6,and molar ratio of SDS to lauraldehyde being 0.15:1. Compared to ordinary reactions,the preparation of N-alkyl chitosan by microwave irradiation can be finished within very short reaction time.
2005, 22(12): 1360-1362
Abstract:
A novel phosphorus-containing copolycarbonate was synthesized from bisphenol-A,2-(6-oxido-6H-dibenz<1,2>oxa phosphorin-6-yl)-1,4-dihydroxy phenylene(ODOP-HQ) and triphosgene by interfacial polycondensation,and a copolycarbonate with an inherent viscosity of 0.53 dL/g was obtained.The copolymer was characterized by elemental analysis,FT-IR,DSC,TGA,and NMR.DSC result shows that the Tg of the copolycarbonate is 149℃,which is higher than that of normal PC.The TGA result shows that the onset decomposition temperature of the copolycarbonate is 355℃,which indicates it possesses a good thermal stability.
A novel phosphorus-containing copolycarbonate was synthesized from bisphenol-A,2-(6-oxido-6H-dibenz
2005, 22(12): 1363-1365
Abstract:
A spectrophotometric method for the determination of azithromycin has been developed based on the charge transfer reaction.The reaction between azithromycin and 7,7,8,8-tetracyanoquinodemethane((TCNQ)) was completed in acetone medium in 30 minutes at 50℃.Beer's law is obeyed in the range of 12.1~867.6 mg/L for the determination of azithromycin.The molar absorptivity of the complex at 745 nm is 1.44×103 L/(mol·cm).The relative standard deviation is 0.96%(n=10).The composition ratio of the charge transfer complex was found to be 1:1 by means of the slope ratio and Job's methods.This method has been applied to the determination of azithromycin in tablets with satisfactory results compared with the Pharmacopoeia method.Recovery was 100.5%.
A spectrophotometric method for the determination of azithromycin has been developed based on the charge transfer reaction.The reaction between azithromycin and 7,7,8,8-tetracyanoquinodemethane((TCNQ)) was completed in acetone medium in 30 minutes at 50℃.Beer's law is obeyed in the range of 12.1~867.6 mg/L for the determination of azithromycin.The molar absorptivity of the complex at 745 nm is 1.44×103 L/(mol·cm).The relative standard deviation is 0.96%(n=10).The composition ratio of the charge transfer complex was found to be 1:1 by means of the slope ratio and Job's methods.This method has been applied to the determination of azithromycin in tablets with satisfactory results compared with the Pharmacopoeia method.Recovery was 100.5%.
2005, 22(12): 1366-1368
Abstract:
The synthesis of diethoxy methane was studied using ethanol and formaldehyde as the raw materials and toluene-p-sulfonic acid as the catalyst.It was found that when the mole ratio of ethanol to formaldehyde was 3.97:1,the mole ratio of toluene-p-sulfonic acid to the total raw materials 7%,the reaction temperature 25℃,the stirring speed 70 r/min and the reaction time 10 min,the yield of DEM was about 90.4%.Under the above reaction conditions,the yield was about 62.3% using HCl as the catalyst,and the amount of water in the product was higher and the waste acid in the continuous reaction would pollute the environment.In addition toluene-p-sulfonic acid can be used repeatedly.Therefore,this synthesis method is useful the practical production of diethoxy methane.
The synthesis of diethoxy methane was studied using ethanol and formaldehyde as the raw materials and toluene-p-sulfonic acid as the catalyst.It was found that when the mole ratio of ethanol to formaldehyde was 3.97:1,the mole ratio of toluene-p-sulfonic acid to the total raw materials 7%,the reaction temperature 25℃,the stirring speed 70 r/min and the reaction time 10 min,the yield of DEM was about 90.4%.Under the above reaction conditions,the yield was about 62.3% using HCl as the catalyst,and the amount of water in the product was higher and the waste acid in the continuous reaction would pollute the environment.In addition toluene-p-sulfonic acid can be used repeatedly.Therefore,this synthesis method is useful the practical production of diethoxy methane.
2005, 22(12): 1369-1371
Abstract:
This paper presents a vacuum-cavitated extraction method for glycyrrhizic acid(GA) extraction from supercritical extraction residue.The optimum extraction conditions are as follows:0.3% ammonia solution as the solvent,the ratio of solvent to solid 10:1(mL/g),vacuum-cavitated time 15 min,and the crude extract yeild is 30.3%,in which the content of GA is 6.6%,so the GA extraction yeild is 2.0%.There are three extraction methods:soxhlet,ultrasonic wave,and vacuum-cavitated extraction methods.The results show that the extraction yield of GA by vacuum-cavitated extraction method is 1.6 times that by soxhlet extraction method and 1.2 times that by ultrasonic.At the same time,the vacuum-cavitated extraction method shows many advantages,including lower temperature,less solvent,shorter extraction time,higher extraction yield,and higher GA content in the crude extract.The vacuum-cavitated extraction method is new and highly efficient,which can be utilized in the pharmaceutical industry.
This paper presents a vacuum-cavitated extraction method for glycyrrhizic acid(GA) extraction from supercritical extraction residue.The optimum extraction conditions are as follows:0.3% ammonia solution as the solvent,the ratio of solvent to solid 10:1(mL/g),vacuum-cavitated time 15 min,and the crude extract yeild is 30.3%,in which the content of GA is 6.6%,so the GA extraction yeild is 2.0%.There are three extraction methods:soxhlet,ultrasonic wave,and vacuum-cavitated extraction methods.The results show that the extraction yield of GA by vacuum-cavitated extraction method is 1.6 times that by soxhlet extraction method and 1.2 times that by ultrasonic.At the same time,the vacuum-cavitated extraction method shows many advantages,including lower temperature,less solvent,shorter extraction time,higher extraction yield,and higher GA content in the crude extract.The vacuum-cavitated extraction method is new and highly efficient,which can be utilized in the pharmaceutical industry.
2005, 22(12): 1372-1374
Abstract:
A novel chiral stationary phase(CSP) was prepared by immobilizing coupled quinine,which was synthesized by the reaction of quinine with 4,4'-diphenyl methane diisocyanate(MDI),onto the surface of 3-mercaptopropyl-silanized silica gel via radical reaction in the presence of 2,2'-azobisisobutyronitrile(AIBN).With the conventional slurry packing method,a column was packed with the newly synthesized CSP material.By means of high performance liquid chromatography,the chromatographic properties of this column were tested with five chiral compounds under different mobile phases.The results obtained indicate that chloropheniramine,1,1'-bi-2-naphthol,promethazine and propranolol were resolved into their enantiomers,and their separation factors were 2.08,1.27,1.43 and 1.16,respectively.Furthermore,a possible chiral resolution mechanism was proposed.
A novel chiral stationary phase(CSP) was prepared by immobilizing coupled quinine,which was synthesized by the reaction of quinine with 4,4'-diphenyl methane diisocyanate(MDI),onto the surface of 3-mercaptopropyl-silanized silica gel via radical reaction in the presence of 2,2'-azobisisobutyronitrile(AIBN).With the conventional slurry packing method,a column was packed with the newly synthesized CSP material.By means of high performance liquid chromatography,the chromatographic properties of this column were tested with five chiral compounds under different mobile phases.The results obtained indicate that chloropheniramine,1,1'-bi-2-naphthol,promethazine and propranolol were resolved into their enantiomers,and their separation factors were 2.08,1.27,1.43 and 1.16,respectively.Furthermore,a possible chiral resolution mechanism was proposed.
2005, 22(12): 1375-1377
Abstract:
By screening solvents and surfactants,a surfactant with strong wetting and dispersing ability has been discovered,which can form stable emulsions.An O/W emulsifier that can inhibit paraffin deposition and remove it has been acquired by an orthogonal design of experiment.The density of the emulsion is 0.9 g/cm3,the removal rate of paraffin is 150 g/(mL·min),and the inhibiting rate of paraffin is 20.70%.When 0.8%~1.5%(mass fraction) sodium chloride is added to the emulsion,the deemulsification time is 1.5~4.0 h.
By screening solvents and surfactants,a surfactant with strong wetting and dispersing ability has been discovered,which can form stable emulsions.An O/W emulsifier that can inhibit paraffin deposition and remove it has been acquired by an orthogonal design of experiment.The density of the emulsion is 0.9 g/cm3,the removal rate of paraffin is 150 g/(mL·min),and the inhibiting rate of paraffin is 20.70%.When 0.8%~1.5%(mass fraction) sodium chloride is added to the emulsion,the deemulsification time is 1.5~4.0 h.
2005, 22(12): 1378-1380
Abstract:
Complex[Tb(2-FC6H4COO)3·C10H8N2]2 was synthesized from TbCl3·nH2O,2-fluorobenzoic acid,and 2,2'-bipyridine(C10H8N2]2).The crystals are monoclinic with space group P21/n,and the crystal parameters are:a=1.219 1(4) nm,b=1.777 4(6) nm,c=1.371 5(4) nm,β=111.400(5),M=732.41,V=2.767(15) nm3,Z=4,Dcalc=1.758 g/cm3,T=293(2) K.The final R=0.030 2,wR=0.054 7.The two Tb3+ ions are linked together by four 2-fluorobenzoate groups in a bridging mode to form a dimeric unit.Each Tb3+ ion is also chelated by one 2-fluorobenzoate group and one 2,2'-bipy ligand,making a coordination number of eight.There are four emission peaks in the luminescence spectrum at 490,545,584,and 618 nm,corresponding to the transitions of the Tb3+ ion:5D4→7D6,5D4→7D5,5D4→7D4,and 5D4→7D3,respectively.
Complex[Tb(2-FC6H4COO)3·C10H8N2]2 was synthesized from TbCl3·nH2O,2-fluorobenzoic acid,and 2,2'-bipyridine(C10H8N2]2).The crystals are monoclinic with space group P21/n,and the crystal parameters are:a=1.219 1(4) nm,b=1.777 4(6) nm,c=1.371 5(4) nm,β=111.400(5),M=732.41,V=2.767(15) nm3,Z=4,Dcalc=1.758 g/cm3,T=293(2) K.The final R=0.030 2,wR=0.054 7.The two Tb3+ ions are linked together by four 2-fluorobenzoate groups in a bridging mode to form a dimeric unit.Each Tb3+ ion is also chelated by one 2-fluorobenzoate group and one 2,2'-bipy ligand,making a coordination number of eight.There are four emission peaks in the luminescence spectrum at 490,545,584,and 618 nm,corresponding to the transitions of the Tb3+ ion:5D4→7D6,5D4→7D5,5D4→7D4,and 5D4→7D3,respectively.
2005, 22(12): 1381-1383
Abstract:
The reduction products of hydroxyl anthraquinone by using zinc powder in acetic acid were obtained.The C=C bonds on the anthraquinone ring can be reduced by the zinc in the acetic acid and the carbonyls of anthraquinone are not reduced.After the hydroxyls of anthraquinone have been protected,the carbonyls of anthraquinone are reduced and the C=C bonds on the anthraquinone ring not reduced.Four new reduction products of anthraquinone were prepared with this method.The structures of these products were confirmed by NMR,IR and MS.
The reduction products of hydroxyl anthraquinone by using zinc powder in acetic acid were obtained.The C=C bonds on the anthraquinone ring can be reduced by the zinc in the acetic acid and the carbonyls of anthraquinone are not reduced.After the hydroxyls of anthraquinone have been protected,the carbonyls of anthraquinone are reduced and the C=C bonds on the anthraquinone ring not reduced.Four new reduction products of anthraquinone were prepared with this method.The structures of these products were confirmed by NMR,IR and MS.
2005, 22(12): 1384-1386
Abstract:
N,N-Diisopropylethanoamine was synthesized from diisopropylamine and ethylene oxide,and then chloridized to N,N-diisopropyl-2-aminoethyl chloride,which finally went through amindysis in benzene to produce the title product N,N-diisopropyl ethanediamine.In these reactions,the optimum molar ratios were 1.2:1 for ethylene oxide to diisopropylamine,2:1 for thionyl chloride to N,N-diisoproylethanoamine,and 12:1 for ammonia to N,N-diisopropyl-2-aminoethyl chloride,respectively.The suitable reaction time,temperature,and solvent were also discussed.The total yield of 81.4% was obtained for the title product.
N,N-Diisopropylethanoamine was synthesized from diisopropylamine and ethylene oxide,and then chloridized to N,N-diisopropyl-2-aminoethyl chloride,which finally went through amindysis in benzene to produce the title product N,N-diisopropyl ethanediamine.In these reactions,the optimum molar ratios were 1.2:1 for ethylene oxide to diisopropylamine,2:1 for thionyl chloride to N,N-diisoproylethanoamine,and 12:1 for ammonia to N,N-diisopropyl-2-aminoethyl chloride,respectively.The suitable reaction time,temperature,and solvent were also discussed.The total yield of 81.4% was obtained for the title product.
2005, 22(12): 1387-1389
Abstract:
Tea polyphenols(TP) were prepared by a complexing precipitation processs with an aluminium salt as the complexing agent.This study mainly focuses on the recycle of the complex agent,and the effect of Fe3+ content on the product yield was investigated.At 30~50℃ and pH 5~6,the TP in 200 g of green tea formed complex with 65 g of hydrous aluminium chloride.The precipitate obtained was washed with deionized water thoroughly,acidified with 10% hydrochloric acid, and then extracted with an equivalent volume of ethyl acetate.The ethyl acetate solution of TP was concentrated to produce crude TP with a yield of up to 11.94% and a purity of 90%.The experimental data also show great reduction in TP yield when Fe(Ⅲ) was involved in the precipitation process of the aluminium salt.In the absence of ferric iron,the aluminium complex agent can be recycled at least 3 times with TP yields of more than 10% and the purity higher than 88%.
Tea polyphenols(TP) were prepared by a complexing precipitation processs with an aluminium salt as the complexing agent.This study mainly focuses on the recycle of the complex agent,and the effect of Fe3+ content on the product yield was investigated.At 30~50℃ and pH 5~6,the TP in 200 g of green tea formed complex with 65 g of hydrous aluminium chloride.The precipitate obtained was washed with deionized water thoroughly,acidified with 10% hydrochloric acid, and then extracted with an equivalent volume of ethyl acetate.The ethyl acetate solution of TP was concentrated to produce crude TP with a yield of up to 11.94% and a purity of 90%.The experimental data also show great reduction in TP yield when Fe(Ⅲ) was involved in the precipitation process of the aluminium salt.In the absence of ferric iron,the aluminium complex agent can be recycled at least 3 times with TP yields of more than 10% and the purity higher than 88%.
2005, 22(12): 1390-1392
Abstract:
A method for determination of olefin hydrocarbons in gasoline products by nearinfrared spectroscopy is presented.The alkene content in the gasoline samples,which were used as the training set for building the calibration model,was determined by detailed hydrocarbon analysis.The spectral data of 1 000~2 000 nm were optimized by using Fourier transform near-infrared spectrometry together with cross validated partial least-squares regression.The mean error between the determined values by detailed hydrocarbon analysis and the predicted values for the training set samples was 0.2%,and an excellent correlation was obtained (R2=0.988 1).The mean error for unknown samples determined by detailed hydrocarbon analysis and NIR was 0.39%.
A method for determination of olefin hydrocarbons in gasoline products by nearinfrared spectroscopy is presented.The alkene content in the gasoline samples,which were used as the training set for building the calibration model,was determined by detailed hydrocarbon analysis.The spectral data of 1 000~2 000 nm were optimized by using Fourier transform near-infrared spectrometry together with cross validated partial least-squares regression.The mean error between the determined values by detailed hydrocarbon analysis and the predicted values for the training set samples was 0.2%,and an excellent correlation was obtained (R2=0.988 1).The mean error for unknown samples determined by detailed hydrocarbon analysis and NIR was 0.39%.
