Login In
1996 Volume 7 Issue 1
1996, 7(1): 1-4
Abstract:
The photoinduced intramolecular arene-olefin meta-cycloaddition of 1 gave regio-selectixely products 2a and 2b,whereas under the same conditions, 3a and 3b provided 4a and 4b respectively.The structure of the photo products was established by detailed 2D-NMR methodology.The observed regioselectivity was rationalized in terms of the stabilization of the zwitterionic intermediates by alkyl group at the phenyl ring.
The photoinduced intramolecular arene-olefin meta-cycloaddition of 1 gave regio-selectixely products 2a and 2b,whereas under the same conditions, 3a and 3b provided 4a and 4b respectively.The structure of the photo products was established by detailed 2D-NMR methodology.The observed regioselectivity was rationalized in terms of the stabilization of the zwitterionic intermediates by alkyl group at the phenyl ring.
1996, 7(1): 5-6
Abstract:
The addition reaction of Grignard reagents to α-cinnamoyl ketene (1,3-propylene) dithioacetals was performed.The experiments show that the addition proceeds completely in a conjugated 1,4-manner.Possible mechanism for the reaction selectivity is discussed.
The addition reaction of Grignard reagents to α-cinnamoyl ketene (1,3-propylene) dithioacetals was performed.The experiments show that the addition proceeds completely in a conjugated 1,4-manner.Possible mechanism for the reaction selectivity is discussed.
1996, 7(1): 7-8
Abstract:
Oxidation of benzoin with air in the presence of a catalytic amount of cobalt salts was studied.By this reaction,benzil was conveniently prepared in excellent yield.
Oxidation of benzoin with air in the presence of a catalytic amount of cobalt salts was studied.By this reaction,benzil was conveniently prepared in excellent yield.
1996, 7(1): 9-10
Abstract:
The aminomethylation of the title compound can occur at 2-C or 5-C when it undergoes Mannich reaction with different amines.With aliphatic secondary amines,the reaction occurs at 2-C of the ketone,whereas with aromatic primary amines under certain conditions,at 5-C of the ketone.
The aminomethylation of the title compound can occur at 2-C or 5-C when it undergoes Mannich reaction with different amines.With aliphatic secondary amines,the reaction occurs at 2-C of the ketone,whereas with aromatic primary amines under certain conditions,at 5-C of the ketone.
1996, 7(1): 11-12
Abstract:
Exiguaflavanone K was first synthesized via the condensation of 2-hydroxy-3-prenyl-4,6-dimethoxymethoxyacetophenone with 3-methoxy-4-methoxymethoxybenzaldehyde followed by cyciization and demethoxymethylation.
Exiguaflavanone K was first synthesized via the condensation of 2-hydroxy-3-prenyl-4,6-dimethoxymethoxyacetophenone with 3-methoxy-4-methoxymethoxybenzaldehyde followed by cyciization and demethoxymethylation.
1996, 7(1): 13-14
Abstract:
Palladium acetate catalyzed cyclization of 1-[(6-bromo-1,3-benzodioxol-5-yl)carbonyl] 2,3-dihydro-1H-indole (7a) leading to the anhydrolycorine-7-one (1a) as the key step in a new synthesis of Crinum alkaloids is described.
Palladium acetate catalyzed cyclization of 1-[(6-bromo-1,3-benzodioxol-5-yl)carbonyl] 2,3-dihydro-1H-indole (7a) leading to the anhydrolycorine-7-one (1a) as the key step in a new synthesis of Crinum alkaloids is described.
1996, 7(1): 15-18
Abstract:
Ozonolysis of compounds 3a-3e and 6 in dichloromethane at-78℃ followed by reduction with dimethylsulfide gave the novel triacetal oxa-cage compounds 5a-5e and 7 in moderate yields respectively.
Ozonolysis of compounds 3a-3e and 6 in dichloromethane at-78℃ followed by reduction with dimethylsulfide gave the novel triacetal oxa-cage compounds 5a-5e and 7 in moderate yields respectively.
1996, 7(1): 19-22
Abstract:
A new acetogenin 2,4-cis-isoannonareticin (2-1) (2,4-cis-bullatacinone) and a known bullatacinone (2,4-trans-isoannonareticin) (2-2) were a pair of isomers epimeric at C-2 which were isolated as two pure natural compounds from Annona reticulata L. by using preparative TLC.Their structures and the relative stereochemistry were elucidated on the basis of the spectral analysis.
A new acetogenin 2,4-cis-isoannonareticin (2-1) (2,4-cis-bullatacinone) and a known bullatacinone (2,4-trans-isoannonareticin) (2-2) were a pair of isomers epimeric at C-2 which were isolated as two pure natural compounds from Annona reticulata L. by using preparative TLC.Their structures and the relative stereochemistry were elucidated on the basis of the spectral analysis.
1996, 7(1): 23-24
Abstract:
A new α-pyrone derivative,epimedokoreanone A was isolated from the aerial parts of Epimedium koreanum. Nakai.Its structure was determined by spectroscopic methods (IR,MS,1H NMR,13C NMR,DEPT,1H-13C COSY and 1H-13C long range COSY).
A new α-pyrone derivative,epimedokoreanone A was isolated from the aerial parts of Epimedium koreanum. Nakai.Its structure was determined by spectroscopic methods (IR,MS,1H NMR,13C NMR,DEPT,1H-13C COSY and 1H-13C long range COSY).
1996, 7(1): 25-28
Abstract:
Several products(2)-(6) were obtained from Hedychenone(1),a furanoid diterpene,by photosensitized oxidation,and the structures were identified by spectral methods.The mechanism of the reaction was discussed.
Several products(2)-(6) were obtained from Hedychenone(1),a furanoid diterpene,by photosensitized oxidation,and the structures were identified by spectral methods.The mechanism of the reaction was discussed.
1996, 7(1): 29-32
Abstract:
The conformation analysis of the donor substrate,guanosine-5'-diphospho-fucose(GDP-fucose),via model compound to mimic the complex of GDP-fucose with divalent cation is performed by means of molecular dynamics,energy minimization and grid scan technique.
The conformation analysis of the donor substrate,guanosine-5'-diphospho-fucose(GDP-fucose),via model compound to mimic the complex of GDP-fucose with divalent cation is performed by means of molecular dynamics,energy minimization and grid scan technique.
1996, 7(1): 33-34
Abstract:
The polarographic and voltammetric behavior of 6-mercaptopurine were studied by several electrochemical techniques.There are two reduction peaks in HAc-NaAc buffer solution at pH 4.0.The characteristics of the second peak (P2) were studied in detail.The relationship between P2 current (ip2) and concentration of 6-mercaptopurine is linear in the range of 1×10-7~1×10-4mol/L.It has been applied to quantitative analysis of an anticancer tablet with satisfying results.The mechaniam of the electrode reaction was proposed also.
The polarographic and voltammetric behavior of 6-mercaptopurine were studied by several electrochemical techniques.There are two reduction peaks in HAc-NaAc buffer solution at pH 4.0.The characteristics of the second peak (P2) were studied in detail.The relationship between P2 current (ip2) and concentration of 6-mercaptopurine is linear in the range of 1×10-7~1×10-4mol/L.It has been applied to quantitative analysis of an anticancer tablet with satisfying results.The mechaniam of the electrode reaction was proposed also.
1996, 7(1): 35-38
Abstract:
The design of a simple and reproducible sample injection system for capillary electrophoresis is described in the present work.In this system,two capillaries are coupled together with a section of controlled porous glass (CPG). When the oncolumn CPG section is immersed in a buffer reservoir along with an electrode to allow a potential to be applied across just one capillary,the Strang electroosmotie flow generated in this capillary serves to pull the analyte into the other capillary.With this sample introduction system,the RSD for peak height over 20 runs was ca.2.8%.
The design of a simple and reproducible sample injection system for capillary electrophoresis is described in the present work.In this system,two capillaries are coupled together with a section of controlled porous glass (CPG). When the oncolumn CPG section is immersed in a buffer reservoir along with an electrode to allow a potential to be applied across just one capillary,the Strang electroosmotie flow generated in this capillary serves to pull the analyte into the other capillary.With this sample introduction system,the RSD for peak height over 20 runs was ca.2.8%.
1996, 7(1): 39-42
Abstract:
A highly sensitive laser induced fluorescence detector for capillary electrophoresis is described.With an argon laser at 488 nm for excitation,the emitted light was collected by an optical fiber and measured by a PMT.Various elements that affected the sensitivity of the detector were discussed in detail.The detection limit for fluorescein was 5.4 amole.
A highly sensitive laser induced fluorescence detector for capillary electrophoresis is described.With an argon laser at 488 nm for excitation,the emitted light was collected by an optical fiber and measured by a PMT.Various elements that affected the sensitivity of the detector were discussed in detail.The detection limit for fluorescein was 5.4 amole.
1996, 7(1): 43-46
Abstract:
Voltammetric properties of didodecyldimethylammonium bromide (DDAB) films containing nickel phthalocyanine (NiPc) were examined.NiPc-DDAB film electrode shows stable voltammetric response in KBr water solution and can catalyze reductions of halogenated acetic acids.The reduction potentials for all substrates studied shifted positive by 0.4-0.6 V.
Voltammetric properties of didodecyldimethylammonium bromide (DDAB) films containing nickel phthalocyanine (NiPc) were examined.NiPc-DDAB film electrode shows stable voltammetric response in KBr water solution and can catalyze reductions of halogenated acetic acids.The reduction potentials for all substrates studied shifted positive by 0.4-0.6 V.
1996, 7(1): 47-50
Abstract:
Silica immobilized N,N'-bis[-2-(benzimidazolylmethyl)]amino-ferrous acetate complexes (Ⅳ) catalyzed monooxygenation of cyclohexane to cyclohexanol with the turnover number 8.4 (equivalent C%=11.2) under mild conditions.The methylene blue is the most effective electron transfer agent which can also regulate products distribution.The iron content of the polymer-supported complexes,the redox potentials and the concentration of methylene blue greatly affect the activity and selectivity of the complex (Ⅳ).
Silica immobilized N,N'-bis[-2-(benzimidazolylmethyl)]amino-ferrous acetate complexes (Ⅳ) catalyzed monooxygenation of cyclohexane to cyclohexanol with the turnover number 8.4 (equivalent C%=11.2) under mild conditions.The methylene blue is the most effective electron transfer agent which can also regulate products distribution.The iron content of the polymer-supported complexes,the redox potentials and the concentration of methylene blue greatly affect the activity and selectivity of the complex (Ⅳ).
1996, 7(1): 51-54
Abstract:
The dissociation constant of arachidic acid on a subphase containing Ag+ ion was measured by IR and LB techniques.
The dissociation constant of arachidic acid on a subphase containing Ag+ ion was measured by IR and LB techniques.
1996, 7(1): 55-58
Abstract:
Hybrid zinc(Ⅱ) and iron(Ⅲ) porphyrin dimer,linked with a short flexible hydrocarbon chain(Fig.1),has been synthesized and characterized by EA,IR,1H-NMR,XPS,and EPR spectroscopy.As a new model system of cytochrome P450,hybrid zinc(Ⅱ) and iron(Ⅲ) porphyrin dimer like iron(Ⅲ) porphyrin effectively catalyze hydroxylation of cyclohexane with molecular oxygen under mild conditions and catalytic activities of dimer are higher than those of iron(Ⅲ) porphyrin.Factors affecting catalytic activities are discussed from the point of view of partial intramolecular redox.
Hybrid zinc(Ⅱ) and iron(Ⅲ) porphyrin dimer,linked with a short flexible hydrocarbon chain(Fig.1),has been synthesized and characterized by EA,IR,1H-NMR,XPS,and EPR spectroscopy.As a new model system of cytochrome P450,hybrid zinc(Ⅱ) and iron(Ⅲ) porphyrin dimer like iron(Ⅲ) porphyrin effectively catalyze hydroxylation of cyclohexane with molecular oxygen under mild conditions and catalytic activities of dimer are higher than those of iron(Ⅲ) porphyrin.Factors affecting catalytic activities are discussed from the point of view of partial intramolecular redox.
1996, 7(1): 59-62
Abstract:
Results of ab initio SCF calculation of 1,2-dithiosquaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dithione) are reported.The ZZ isomer is found to be the most stable of the three isomers.An isodesmic energy analysis has been carried out at the HF 6-31G'//6-31G' level for the three planar isomers.The three isomers have positive isodesmic energies or small negative ones,suggesting that 1,2-dithiosquaric acid is not aromatic.Vibrational frequencies have also been calculated for the three isomers.
Results of ab initio SCF calculation of 1,2-dithiosquaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dithione) are reported.The ZZ isomer is found to be the most stable of the three isomers.An isodesmic energy analysis has been carried out at the HF 6-31G'//6-31G' level for the three planar isomers.The three isomers have positive isodesmic energies or small negative ones,suggesting that 1,2-dithiosquaric acid is not aromatic.Vibrational frequencies have also been calculated for the three isomers.
1996, 7(1): 63-66
Abstract:
A Monte Carlo method has been proposed for direct simulating the thermodynamic quantities of a single self-avoiding walk chain with the neighbour interaction on a simple cubic lattice.The simulation data of me conformational entropy of me chain length 16 have been found to be consistent very well with the exact results obtained by the direct counting method.
A Monte Carlo method has been proposed for direct simulating the thermodynamic quantities of a single self-avoiding walk chain with the neighbour interaction on a simple cubic lattice.The simulation data of me conformational entropy of me chain length 16 have been found to be consistent very well with the exact results obtained by the direct counting method.
1996, 7(1): 67-70
Abstract:
An investigation has been undertaken by use of ESCA in the characterization of the central metal(Zr) of dichlorozirconocene/methylaluminoxane homogeneous olefin polymerization catalyst.The change of electron density shown by a shift in ESCA signals (181.8→182.7eV) indicates that the catalytic species are "cation-like".Within the range of detecting sensitivity of ESCA spectrometer,only a part of the new catalytic derivative was formed.The influence of complexion time and Al:Zr ratio on the formation of the catalytic zirconocene cation has also been investigated.
An investigation has been undertaken by use of ESCA in the characterization of the central metal(Zr) of dichlorozirconocene/methylaluminoxane homogeneous olefin polymerization catalyst.The change of electron density shown by a shift in ESCA signals (181.8→182.7eV) indicates that the catalytic species are "cation-like".Within the range of detecting sensitivity of ESCA spectrometer,only a part of the new catalytic derivative was formed.The influence of complexion time and Al:Zr ratio on the formation of the catalytic zirconocene cation has also been investigated.
1996, 7(1): 71-72
Abstract:
Linear poiybenzonitrile with carbon-nitrogen conjugated backbones was prepared by piasma polymerization techniques.The ultrafast Kerr effect of polymer in DMF solution was examined with femtosecond laser pulses.Second order hyperpolarizability varied with polymerization degrees.
Linear poiybenzonitrile with carbon-nitrogen conjugated backbones was prepared by piasma polymerization techniques.The ultrafast Kerr effect of polymer in DMF solution was examined with femtosecond laser pulses.Second order hyperpolarizability varied with polymerization degrees.
1996, 7(1): 73-74
Abstract:
The effects of thermal treatment on microstructure of the polyesters were studied.Annealing below Tc-n,physical diffusion processes dominate to yield an increasing crystallinity along with increased molecular weight,transesterification reactions are limited to the end groups and the microstructure had not changed.Annealing near Tc-n,chemical processes dominate and simultaneously make the microdomains ordered more perfectly.Analysis by 13C NMR proved that interchain transesterification had occurred.
The effects of thermal treatment on microstructure of the polyesters were studied.Annealing below Tc-n,physical diffusion processes dominate to yield an increasing crystallinity along with increased molecular weight,transesterification reactions are limited to the end groups and the microstructure had not changed.Annealing near Tc-n,chemical processes dominate and simultaneously make the microdomains ordered more perfectly.Analysis by 13C NMR proved that interchain transesterification had occurred.
1996, 7(1): 75-76
Abstract:
A new kind of polymer gel electrolyte which is composed of polytriethylene glycol dimethacrylate(PTREGD),propylene carbonate(PC) and LiPF6 has been prepared by thermal polymerization.The conductivity was measured as a function of temperature,and it was found that the Arrhenius equation was held very well through out the salt concentration studied.Maximum room temperature conductivity of 4.95×10-4S/cm,as well as a minimum activation energy value of 18.90 kJ/mol were obtained at the same salt concentration of 0.22 mol/L.
A new kind of polymer gel electrolyte which is composed of polytriethylene glycol dimethacrylate(PTREGD),propylene carbonate(PC) and LiPF6 has been prepared by thermal polymerization.The conductivity was measured as a function of temperature,and it was found that the Arrhenius equation was held very well through out the salt concentration studied.Maximum room temperature conductivity of 4.95×10-4S/cm,as well as a minimum activation energy value of 18.90 kJ/mol were obtained at the same salt concentration of 0.22 mol/L.
1996, 7(1): 77-80
Abstract:
The influence of different size of gold nanometer particles (1Onm,20nm,30-40nm) on the glucose oxidase enzyme electrode response has been investigated by using a sol-gel method which is simple and easy to study this phenomena quantitatively.The response electric current was increased with the increase of the ratio of gold to GOD.The mechanism of this effect has been discussed.
The influence of different size of gold nanometer particles (1Onm,20nm,30-40nm) on the glucose oxidase enzyme electrode response has been investigated by using a sol-gel method which is simple and easy to study this phenomena quantitatively.The response electric current was increased with the increase of the ratio of gold to GOD.The mechanism of this effect has been discussed.
1996, 7(1): 81-84
Abstract:
The voltammetric behavior of the titled compound (denoted as Nd (SiMo7W4)213-) in aqueous solution had been studied.An unusual pH response was discussed.The adsorption of the anion on the dropping mercury electrode and a selfinhibition influence of the adsorbed anions on the redox process of those anions dissolved in solution were found.The electrocatalytic effects of the anion on the bromate reduction were investigated.
The voltammetric behavior of the titled compound (denoted as Nd (SiMo7W4)213-) in aqueous solution had been studied.An unusual pH response was discussed.The adsorption of the anion on the dropping mercury electrode and a selfinhibition influence of the adsorbed anions on the redox process of those anions dissolved in solution were found.The electrocatalytic effects of the anion on the bromate reduction were investigated.
1996, 7(1): 85-86
Abstract:
LaMnO3,LaFeO3 and La2NiO4 were synthesized with citrate complexes via microwave irradiation.
LaMnO3,LaFeO3 and La2NiO4 were synthesized with citrate complexes via microwave irradiation.
1996, 7(1): 87-88
Abstract:
The title complex crystallized in space group P21/c with Z=2 in a unit cell of dimensions,a=9.811(1)Å,b=16.851(2)Å,c=15.855(3)Å;β=98.71(1)°, v=2591.0(6)Å3, Dc=1.225gcm-3,F(000)=1024,μ=0.55mm-1,R=0.0338,Rw=0.0631.The geometry of the Pd(Ⅱ)complex is square-planar configuration. The S2C=NPhNH2 group coordinated as asymmetric bidentate ligand forming a stable four member ring by chelation through the two sulphur atoms.
The title complex crystallized in space group P21/c with Z=2 in a unit cell of dimensions,a=9.811(1)Å,b=16.851(2)Å,c=15.855(3)Å;β=98.71(1)°, v=2591.0(6)Å3, Dc=1.225gcm-3,F(000)=1024,μ=0.55mm-1,R=0.0338,Rw=0.0631.The geometry of the Pd(Ⅱ)complex is square-planar configuration. The S2C=NPhNH2 group coordinated as asymmetric bidentate ligand forming a stable four member ring by chelation through the two sulphur atoms.
1996, 7(1): 89-90
Abstract:
The title complexes have been synthesized by the reaction of rare earth nitrate with 2-[2-(3-nitro-4-methoxylphenyl)vinyl]-1-methylpyridinium nitrate in ethanol solution and have been characterized by IR,UV and 1H NMR spectra,TG-DTA,molar conductance and X-ray powder diffraction.The results show that the crystal form of Nd complex containing one molecular water as a ligand is eleven coordinated and is different from the others.
The title complexes have been synthesized by the reaction of rare earth nitrate with 2-[2-(3-nitro-4-methoxylphenyl)vinyl]-1-methylpyridinium nitrate in ethanol solution and have been characterized by IR,UV and 1H NMR spectra,TG-DTA,molar conductance and X-ray powder diffraction.The results show that the crystal form of Nd complex containing one molecular water as a ligand is eleven coordinated and is different from the others.
1996, 7(1): 91-92
Abstract:
The heterobinuclear metal carbonyl complexes (PPh3)3Co(μ-CO)2V(CO)2 Cp and (PPh3) HPt(μ-CO) (μ-PPh2) V(CO)2 Cp were synthesized and characterized by elemental analyses,IR and NMR spectroscopic means.
The heterobinuclear metal carbonyl complexes (PPh3)3Co(μ-CO)2V(CO)2 Cp and (PPh3) HPt(μ-CO) (μ-PPh2) V(CO)2 Cp were synthesized and characterized by elemental analyses,IR and NMR spectroscopic means.
1996, 7(1): 93-94
Abstract:
Upper and lower critical solution temperature (UCST and LCST) behaviours have been examined for solution of PHB/PBHE blends in chloroform and chlorobenzene.Polymer-Solvent systems prepared with various solvents and concentrations were found to possess UCST and LCST characteristics.PHB/PBHE solution in chloroform displayed greater miscibility temperature region than that of the blend in chlorobenzene,but the relative tendency of both UCST and LCST were similar.
Upper and lower critical solution temperature (UCST and LCST) behaviours have been examined for solution of PHB/PBHE blends in chloroform and chlorobenzene.Polymer-Solvent systems prepared with various solvents and concentrations were found to possess UCST and LCST characteristics.PHB/PBHE solution in chloroform displayed greater miscibility temperature region than that of the blend in chlorobenzene,but the relative tendency of both UCST and LCST were similar.
