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1995 Volume 6 Issue 11
1995, 6(11): 927-930
Abstract:
A highly practical asymmetric epoxidation procedure for the synthesis of optically pure epoxychromans has been developed which employs 30% hydrogen peroxied as the oxidant and the Jacobsen-catalyst as the catalyst.The presence of imidazole has a significant effect on epoxidation rates and total turnovers.A variety of chromene derivatives were converted into corresponding epoxides of 89~100% ee in 72~92% isolated yields.
A highly practical asymmetric epoxidation procedure for the synthesis of optically pure epoxychromans has been developed which employs 30% hydrogen peroxied as the oxidant and the Jacobsen-catalyst as the catalyst.The presence of imidazole has a significant effect on epoxidation rates and total turnovers.A variety of chromene derivatives were converted into corresponding epoxides of 89~100% ee in 72~92% isolated yields.
1995, 6(11): 931-934
Abstract:
Selective epoxidation of 11-ene double bond in 11-isopropylidene-endo-tricyclo[6.2.1.02.7]undeca-4,9-diene-3.6-dione (1a) by mCPBA afforded exclusively syn-epoxide 3,3 is much more stable than 1a. Photocycloaddition of 3 resulted the corresponding trishomocubane 4. Single crystal X-ray analysis of 4 was carried out to establish the stereochemistry of the epoxide moiety.
Selective epoxidation of 11-ene double bond in 11-isopropylidene-endo-tricyclo[6.2.1.02.7]undeca-4,9-diene-3.6-dione (1a) by mCPBA afforded exclusively syn-epoxide 3,3 is much more stable than 1a. Photocycloaddition of 3 resulted the corresponding trishomocubane 4. Single crystal X-ray analysis of 4 was carried out to establish the stereochemistry of the epoxide moiety.
1995, 6(11): 935-938
Abstract:
Eight dialkyl tetrabromophthalates(DATBPs) were synthesized by reacting tetrabromophthalic anhydride with excess alcohols which were used not only as a reactant but also as a solvent and using a quaternary ammonium salt as a phase transfer catalyst(PTC).The yields were found to be between 85-93%.Their structures were characterized by IR,NMR and elementary analysis.The flame retardant properties of the compounds were also studied.
Eight dialkyl tetrabromophthalates(DATBPs) were synthesized by reacting tetrabromophthalic anhydride with excess alcohols which were used not only as a reactant but also as a solvent and using a quaternary ammonium salt as a phase transfer catalyst(PTC).The yields were found to be between 85-93%.Their structures were characterized by IR,NMR and elementary analysis.The flame retardant properties of the compounds were also studied.
1995, 6(11): 939-940
Abstract:
The new benzodiazepinic tricyclic compounds were synthesized by condensing o-phenylenediamine with 2-carbethoxycyclopentanone or 2-methyl-5-carbethoxycyclopentanone and the synthesic method was discussed.
The new benzodiazepinic tricyclic compounds were synthesized by condensing o-phenylenediamine with 2-carbethoxycyclopentanone or 2-methyl-5-carbethoxycyclopentanone and the synthesic method was discussed.
1995, 6(11): 941-942
Abstract:
Four analogs and three segments of the Papaver somniferum pollen peptide 2 (PSPP2) were designed and synthesized by using Merrifield solid phase peptide synthesis method.Their anti-tumour activities were determined by the tetrazolium salt MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method and the relationship of structure-activity was discussed.
Four analogs and three segments of the Papaver somniferum pollen peptide 2 (PSPP2) were designed and synthesized by using Merrifield solid phase peptide synthesis method.Their anti-tumour activities were determined by the tetrazolium salt MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method and the relationship of structure-activity was discussed.
1995, 6(11): 943-944
Abstract:
All double bond positional isomers of (Z)-dodecenol,(Z)-tetradecenol,(Z)-hexadecenol and their acetates were synthesized by the Wittig reaction and the coupling reaction,and a novel procedure for the identification of the isomers has been developed by the similarity analysis of mass spectral data in this study.
All double bond positional isomers of (Z)-dodecenol,(Z)-tetradecenol,(Z)-hexadecenol and their acetates were synthesized by the Wittig reaction and the coupling reaction,and a novel procedure for the identification of the isomers has been developed by the similarity analysis of mass spectral data in this study.
1995, 6(11): 945-946
Abstract:
Eight new compounds of(GeCH2CH(CH3) COOAr)2O3 type were synthesized.Four of them were tested for antitumor activities against Hela cells in vitro,showing considerable tumor inhibitory activities.
Eight new compounds of(GeCH2CH(CH3) COOAr)2O3 type were synthesized.Four of them were tested for antitumor activities against Hela cells in vitro,showing considerable tumor inhibitory activities.
1995, 6(11): 947-950
Abstract:
Two single-chain glycolipids,octadecyl-β-D-glucopyranoside(1) and 2-octa-decanamido-2-deoxy-D-glucopyranose(2) were synthesized and their dispersing properties in water were studied.Incorporation of 1 into the phospholipid liposomes could inhibit the aggregation of liposomes and improve the molecular packing in the bilayer membranes.
Two single-chain glycolipids,octadecyl-β-D-glucopyranoside(1) and 2-octa-decanamido-2-deoxy-D-glucopyranose(2) were synthesized and their dispersing properties in water were studied.Incorporation of 1 into the phospholipid liposomes could inhibit the aggregation of liposomes and improve the molecular packing in the bilayer membranes.
1995, 6(11): 951-954
Abstract:
A new series of fully aromatic thermotropic liquid crystalline copolyesters were synthesized by thermal polycondensation of p-hydroxybenzoic acid [PHB],terephthalic acid [TPA],resorcinol [RES] and bis (4-hydroxyphenyl) methanone [BHP].The DSC traces of copolyesters exhibited two or three endotherms,the low temperature endotherm(Tm) of which indicated the transition from solid state to anisotropic phase.Observation under polarizing microscope and WAXD measurements suggested that the LC-phase formed immediately above Tm had a nematic character.
A new series of fully aromatic thermotropic liquid crystalline copolyesters were synthesized by thermal polycondensation of p-hydroxybenzoic acid [PHB],terephthalic acid [TPA],resorcinol [RES] and bis (4-hydroxyphenyl) methanone [BHP].The DSC traces of copolyesters exhibited two or three endotherms,the low temperature endotherm(Tm) of which indicated the transition from solid state to anisotropic phase.Observation under polarizing microscope and WAXD measurements suggested that the LC-phase formed immediately above Tm had a nematic character.
1995, 6(11): 955-958
Abstract:
The 1,3-dioxolanes,1,3-dioxanes and open chain acetals or ketals are easily cleavaged by using sodium hydrogen selenide under basic conditions in high yields.
The 1,3-dioxolanes,1,3-dioxanes and open chain acetals or ketals are easily cleavaged by using sodium hydrogen selenide under basic conditions in high yields.
1995, 6(11): 959-960
Abstract:
The reactions of 1,1'-binaphthyl-2,2'-diylphosphoryl chloride with optically pure amines give diastcreo-selective products with the de% from 20% to 82%.
The reactions of 1,1'-binaphthyl-2,2'-diylphosphoryl chloride with optically pure amines give diastcreo-selective products with the de% from 20% to 82%.
1995, 6(11): 961-964
Abstract:
The mechanism of the reaction of the CH radical with NH3 has been theoretically studied at the MP2/6-31G** level.The calculation results indicate that the insertion reaction path is the favourable channel,which is in line with Lin's proposal based on their kinetic experiments.A detailed description of the complicated insertion reaction path is presented.
The mechanism of the reaction of the CH radical with NH3 has been theoretically studied at the MP2/6-31G** level.The calculation results indicate that the insertion reaction path is the favourable channel,which is in line with Lin's proposal based on their kinetic experiments.A detailed description of the complicated insertion reaction path is presented.
1995, 6(11): 965-966
Abstract:
A new iridoid,6'-acetyl asperuloside was isolated from the whole plant of Hedyotis crysotrichae.Its structure has been elucidated by means of 1H-NMR and 13C-NMR spectra.
A new iridoid,6'-acetyl asperuloside was isolated from the whole plant of Hedyotis crysotrichae.Its structure has been elucidated by means of 1H-NMR and 13C-NMR spectra.
1995, 6(11): 967-970
Abstract:
Two new taxoids,named taxawallin A(1) and taxawallin G(2) were isolated from the needles of Taxus wallichiana Zucc..Their structures were established by spectral methods.
Two new taxoids,named taxawallin A(1) and taxawallin G(2) were isolated from the needles of Taxus wallichiana Zucc..Their structures were established by spectral methods.
1995, 6(11): 971-974
Abstract:
Four new taxoids with rearranged taxane skeleton,named taxawallins C(1),D(2),F(3) and H(4),were isolated from the needles of Taxus wallichiana Zucc.,Their structures were elucidated by spectroscopic techniques.
Four new taxoids with rearranged taxane skeleton,named taxawallins C(1),D(2),F(3) and H(4),were isolated from the needles of Taxus wallichiana Zucc.,Their structures were elucidated by spectroscopic techniques.
1995, 6(11): 975-978
Abstract:
The direct determination of NO2 gas using a galvanic coulometric cell as detector by gas flow injection analysis (FIA) is described.The simple modification of the flow injection allows the linear range for the determination of NO2 gas from 0.01-2 ppm(v/v) to be expanded to 8-500 ppm(v/v) with a relative standard deviation of 3-4%(n=12) at a rate of 25 samples per hour and avoids the problem of time consuming in the equilibrium performance.
The direct determination of NO2 gas using a galvanic coulometric cell as detector by gas flow injection analysis (FIA) is described.The simple modification of the flow injection allows the linear range for the determination of NO2 gas from 0.01-2 ppm(v/v) to be expanded to 8-500 ppm(v/v) with a relative standard deviation of 3-4%(n=12) at a rate of 25 samples per hour and avoids the problem of time consuming in the equilibrium performance.
1995, 6(11): 979-982
Abstract:
An extraction-free spectrophotometric method for the determination of cationic surfactants is proposed,which is based on the formation of ternary complexes with Fe(Ⅲ) and chrome azurol S.The method gives an apparent molar absorptivity of 6.5×104 L mol-1 cm-1 and a linear range of(0.1-6.0)×10-6 mol/L cationic surfactants,and has been successfully applied to determining cationic surfactants in water.
An extraction-free spectrophotometric method for the determination of cationic surfactants is proposed,which is based on the formation of ternary complexes with Fe(Ⅲ) and chrome azurol S.The method gives an apparent molar absorptivity of 6.5×104 L mol-1 cm-1 and a linear range of(0.1-6.0)×10-6 mol/L cationic surfactants,and has been successfully applied to determining cationic surfactants in water.
1995, 6(11): 983-986
Abstract:
A novel in-situ spectroelectrochemical technique,the combination of probe beam deflection (PBD) with cyclic voltammetry (CV),was used to study the ion cxchange process of prussian blue (PB) modified film electrode in contact with various electrolyte solutions.The ion exchange mechanism was verified as following:K2Fe2+FeⅡ(CN)8???KFe3+FeⅡ(CN)8???[Fe3+FeⅢ(CN)8]x[KFe3+FeⅡ(CN)8]1-x where on reduction PB film in contact with an acidic KCl electrolyte,it was confirmed that protons enter into the PB film before K+ cations.
A novel in-situ spectroelectrochemical technique,the combination of probe beam deflection (PBD) with cyclic voltammetry (CV),was used to study the ion cxchange process of prussian blue (PB) modified film electrode in contact with various electrolyte solutions.The ion exchange mechanism was verified as following:K2Fe2+FeⅡ(CN)8???KFe3+FeⅡ(CN)8???[Fe3+FeⅢ(CN)8]x[KFe3+FeⅡ(CN)8]1-x where on reduction PB film in contact with an acidic KCl electrolyte,it was confirmed that protons enter into the PB film before K+ cations.
1995, 6(11): 987-990
Abstract:
The Lewis acidity scale of boron trihalides BXa(X=F,Cl,Br,I) has been studied by the quantum chemicsl DV-Xα approach.The dipole moments,LUMO energies and the nature of chemical bonds for these molecules have been carried out based on their density of states and orbital populations.A satisfactory interpretation of the experimental acid strength order of boron trihalides can be obtained from our calculated results.
The Lewis acidity scale of boron trihalides BXa(X=F,Cl,Br,I) has been studied by the quantum chemicsl DV-Xα approach.The dipole moments,LUMO energies and the nature of chemical bonds for these molecules have been carried out based on their density of states and orbital populations.A satisfactory interpretation of the experimental acid strength order of boron trihalides can be obtained from our calculated results.
1995, 6(11): 991-994
Abstract:
In this paper a new chemical oscillating reaction in the pyruvic acid-BrO3--H2SO4-[CuL](ClO4)2 system,where L is 5,7,12,14-tetraethyl-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene,is reported.The features of the oscillations are studied in detail.The effects of Ag+, Hg2+, CCl4, Vc, H2O2, acrylonitrile,and temperature on the oscillation system are also discussed.
In this paper a new chemical oscillating reaction in the pyruvic acid-BrO3--H2SO4-[CuL](ClO4)2 system,where L is 5,7,12,14-tetraethyl-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene,is reported.The features of the oscillations are studied in detail.The effects of Ag+, Hg2+, CCl4, Vc, H2O2, acrylonitrile,and temperature on the oscillation system are also discussed.
1995, 6(11): 995-998
Abstract:
In this paper,the solid state redox reaction of[Fe(bpy)3](ClO4)3·3H2O with NaNO2 was studied at room temperature.Mossbauer spectrometry,XRD,FTIR,magnetic susceptibility measurements and elemental analysis were used to characterize the solid product.
In this paper,the solid state redox reaction of[Fe(bpy)3](ClO4)3·3H2O with NaNO2 was studied at room temperature.Mossbauer spectrometry,XRD,FTIR,magnetic susceptibility measurements and elemental analysis were used to characterize the solid product.
1995, 6(11): 999-1002
Abstract:
The binding of [Ru(bpy)2(IP)]2+(b2IP), [Ru(bpy)2(PIP)]2+(b2PIP),[Ru(phen)2(IP)]2+(p2IP), [Ru(phen)2(PIP)]2+(p2PIP) to calf thymus DNA was investigated using electronic absorption,circular dichroism and fluorescence emission spectroscopies.CD spectra of dialyzates indicate enantioselectivity associated with binding.Evidence of intercalative binding is also provided by hypochromicity in the MLCT bands,increased emission intensities and curvature of emission quenching by [Fe(CN)8]4-.The total binding affinities seem to be in the order b2IP < b2PIP ≤ P2IP < P2PIP,which is consistent with the order of ligand planarity,extent of aromatic π-system and hydrophobicity,bpy << phen < IP < PIP.
The binding of [Ru(bpy)2(IP)]2+(b2IP), [Ru(bpy)2(PIP)]2+(b2PIP),[Ru(phen)2(IP)]2+(p2IP), [Ru(phen)2(PIP)]2+(p2PIP) to calf thymus DNA was investigated using electronic absorption,circular dichroism and fluorescence emission spectroscopies.CD spectra of dialyzates indicate enantioselectivity associated with binding.Evidence of intercalative binding is also provided by hypochromicity in the MLCT bands,increased emission intensities and curvature of emission quenching by [Fe(CN)8]4-.The total binding affinities seem to be in the order b2IP < b2PIP ≤ P2IP < P2PIP,which is consistent with the order of ligand planarity,extent of aromatic π-system and hydrophobicity,bpy << phen < IP < PIP.
1995, 6(11): 1003-1004
Abstract:
The oxidative coupling of methane over Li2SO4/BaCe0.93La0.07O3 irradiated by microwave is reported.Compared with conventional heating mode,under the microwave radiation the temperature of catalytic bed is lower and the products were changed in selectivity favouring the production of C2 compounds.
The oxidative coupling of methane over Li2SO4/BaCe0.93La0.07O3 irradiated by microwave is reported.Compared with conventional heating mode,under the microwave radiation the temperature of catalytic bed is lower and the products were changed in selectivity favouring the production of C2 compounds.
1995, 6(11): 1005-1008
Abstract:
Basicity of ZrO2 is enhanced by KF modification due to the reaction of KF with ZrO2 surface:KF+ZrO2→K2ZrF6+KOH.After pretreated above 673K,KF/ZrO2 catalyst exhibited higher activity for 1-butene isomenzation at 273K than ZrO2.The amount of basic sites strongly adsorbing CO2 in the form of bicarbonate was also increased.
Basicity of ZrO2 is enhanced by KF modification due to the reaction of KF with ZrO2 surface:KF+ZrO2→K2ZrF6+KOH.After pretreated above 673K,KF/ZrO2 catalyst exhibited higher activity for 1-butene isomenzation at 273K than ZrO2.The amount of basic sites strongly adsorbing CO2 in the form of bicarbonate was also increased.
1995, 6(11): 1009-1012
Abstract:
The preparation and characterization of some divalent metal ion M(Ⅱ) complexes derived from potassium 3-(benzotriazole-1-carbonylmethyl)-dithiocar-bazate (BCDHK) is reported.The solid complexes of the composition ML·nH2O and ML2·2H2O (M=Pb(Ⅱ),UO2(Ⅱ)),have been characterized on the basis of elemental analyses,IR,UV and TGA.
The preparation and characterization of some divalent metal ion M(Ⅱ) complexes derived from potassium 3-(benzotriazole-1-carbonylmethyl)-dithiocar-bazate (BCDHK) is reported.The solid complexes of the composition ML·nH2O and ML2·2H2O (M=Pb(Ⅱ),UO2(Ⅱ)),have been characterized on the basis of elemental analyses,IR,UV and TGA.
1995, 6(11): 1013-1016
Abstract:
Coated semiconductor CdS/ZnS nanoparticles were fabricated by coating the CdS core with a layer of ZnS in inverse micelle solutions.The optical absorption and photoluminescence(PL) characteristics of the coated CdS/ZnS nanoparticles were investigated and provided evidence for a core-shell structure in these particles.A new PL band with a maximum at 630nm arised from the coated particles and the PL intensity increased with increasing the amount of ZnS coated on the CdS core.
Coated semiconductor CdS/ZnS nanoparticles were fabricated by coating the CdS core with a layer of ZnS in inverse micelle solutions.The optical absorption and photoluminescence(PL) characteristics of the coated CdS/ZnS nanoparticles were investigated and provided evidence for a core-shell structure in these particles.A new PL band with a maximum at 630nm arised from the coated particles and the PL intensity increased with increasing the amount of ZnS coated on the CdS core.
1995, 6(11): 1017-1020
Abstract:
A series of rare earth hydroxides and oxides ultrafine powders have been prepared by precipitation method using alcohol as dispersive and protective reagent.It was first to find that the crystallite size of cubic rare earth oxides had lanthanide shrinking effect,but average crystal lattice distortion rate possessed lanthanide swelling effect;the change of diffraction intensity with atoiaic number presented an inverted W type,and double peaks structure was formed.
A series of rare earth hydroxides and oxides ultrafine powders have been prepared by precipitation method using alcohol as dispersive and protective reagent.It was first to find that the crystallite size of cubic rare earth oxides had lanthanide shrinking effect,but average crystal lattice distortion rate possessed lanthanide swelling effect;the change of diffraction intensity with atoiaic number presented an inverted W type,and double peaks structure was formed.
