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1993 Volume 4 Issue 7
1993, 4(7): 565-566
Abstract:
A convenient synthetic approach leading to protected inositol was described based on regioselective O-alkylation using alkyl halide under solid-liquid PTC condition
A convenient synthetic approach leading to protected inositol was described based on regioselective O-alkylation using alkyl halide under solid-liquid PTC condition
1993, 4(7): 567-568
Abstract:
1.2-Bispyrroleethylenes can be easily syntnesized bv covpling pyrrolealdehyde using TiCl4/Zn as a catalyst.It was found that when the R group is COMe or CO2 Et, the product is a mixture of trans and cis isomers, and in the other cases, the products are pure trans isomers.
1.2-Bispyrroleethylenes can be easily syntnesized bv covpling pyrrolealdehyde using TiCl4/Zn as a catalyst.It was found that when the R group is COMe or CO2 Et, the product is a mixture of trans and cis isomers, and in the other cases, the products are pure trans isomers.
1993, 4(7): 569-572
Abstract:
Synthetic studies on 4-demethyl-qinghaosu involving preparation of key intermediate olefin 5 and its photooxygenation were described.Experiment showed that rearrangement product 4 during the photooxygenation.
Synthetic studies on 4-demethyl-qinghaosu involving preparation of key intermediate olefin 5 and its photooxygenation were described.Experiment showed that rearrangement product 4 during the photooxygenation.
1993, 4(7): 573-576
Abstract:
The reaction of α, β-epoxyketones with methoxymethylenetriphenyl-phosphorane provides a method for the preparation of α-alkylsubstituted γ-hydroxy-α, β-unsaturated aldehydes with one carbon homologation and retention of configuration.
The reaction of α, β-epoxyketones with methoxymethylenetriphenyl-phosphorane provides a method for the preparation of α-alkylsubstituted γ-hydroxy-α, β-unsaturated aldehydes with one carbon homologation and retention of configuration.
1993, 4(7): 577-580
Abstract:
The debromination of diphenyl bromomethane (Ph2CHBr) using polymers with viologen structure as electron-transfer catalyst (ETC) afforded tetraphenylethane in good yields under heterophase conditions.
The debromination of diphenyl bromomethane (Ph2CHBr) using polymers with viologen structure as electron-transfer catalyst (ETC) afforded tetraphenylethane in good yields under heterophase conditions.
1993, 4(7): 581-582
Abstract:
Six hydrophobic peptidyl and four amino acid (L-Val, L-Leu,L-Phe, L-Gly) derivatives of 5-fluorouracil (5-FU) were synthesized.The structure of these compounds were characterized by 1H-NMR, IR,UV spectra and elemental analysis.The antitumor activity was test-ed against EAC cells in vitro.
Six hydrophobic peptidyl and four amino acid (L-Val, L-Leu,L-Phe, L-Gly) derivatives of 5-fluorouracil (5-FU) were synthesized.The structure of these compounds were characterized by 1H-NMR, IR,UV spectra and elemental analysis.The antitumor activity was test-ed against EAC cells in vitro.
1993, 4(7): 583-586
Abstract:
CCl3SO2Br used as a "telogen" reacts with CH2=CF2 to give mainly the "mono-adduct" CCl3CH2CF2Br, together with very small amouats of CCl3CF2CH2Br, CCl2BrCH2CF2Br and the "di-adduct" CCl3 (CH2CF2)2Br.The result indicates that CCl3SO2Br can be used as an addendum in trichloromethyl-bromo-addition reactions to olefins.
CCl3SO2Br used as a "telogen" reacts with CH2=CF2 to give mainly the "mono-adduct" CCl3CH2CF2Br, together with very small amouats of CCl3CF2CH2Br, CCl2BrCH2CF2Br and the "di-adduct" CCl3 (CH2CF2)2Br.The result indicates that CCl3SO2Br can be used as an addendum in trichloromethyl-bromo-addition reactions to olefins.
1993, 4(7): 587-590
Abstract:
Photoinduced charge transfer reaction of benzophenone (BP) with, amine was carried out in the vesicles of dicetyldimethylammonium bromide (DCDAB) over wide ranges of amine concentration (0.01~4.0M).Linear plots of φ-1 vs.[TEA]-1 at low concentration of amine (<0.02M) and Ø-1 vs.[TEA]-2 at high concentration were obtained.Kinetic data demonstrate that the electron transfer is promoted significantly by DCDAB vesicles and proton transfer becomes more efficient at high amlne concentrations, leading to a decrease of Kd/Kr and increase of Kh/Ke.The kinetic expressions of photoreaction of BP bound to DCDAB bilayer are developed.
Photoinduced charge transfer reaction of benzophenone (BP) with, amine was carried out in the vesicles of dicetyldimethylammonium bromide (DCDAB) over wide ranges of amine concentration (0.01~4.0M).Linear plots of φ-1 vs.[TEA]-1 at low concentration of amine (<0.02M) and Ø-1 vs.[TEA]-2 at high concentration were obtained.Kinetic data demonstrate that the electron transfer is promoted significantly by DCDAB vesicles and proton transfer becomes more efficient at high amlne concentrations, leading to a decrease of Kd/Kr and increase of Kh/Ke.The kinetic expressions of photoreaction of BP bound to DCDAB bilayer are developed.
1993, 4(7): 591-592
Abstract:
In this paper, we report an improved method for preparing 2-alkoxy-5-fluoro-3H-4-pyrimidone from 2-chloro-5-fluoro-3H-4-pyrimidone and sodium alkoxide under normal pressure at reflux temperature.Some new compounds were synthesized in higher yield by this method.
In this paper, we report an improved method for preparing 2-alkoxy-5-fluoro-3H-4-pyrimidone from 2-chloro-5-fluoro-3H-4-pyrimidone and sodium alkoxide under normal pressure at reflux temperature.Some new compounds were synthesized in higher yield by this method.
1993, 4(7): 593-596
Abstract:
The anhydrous NdCla-LiNp (LiNp=Lithium uaphthalide) system has been fouud to cause a novel cyclodimerization of α, β-unsaturated ketoues to give cyclopentauol derivatives (1 and 2).A possible reaction mechanism was proposed.
The anhydrous NdCla-LiNp (LiNp=Lithium uaphthalide) system has been fouud to cause a novel cyclodimerization of α, β-unsaturated ketoues to give cyclopentauol derivatives (1 and 2).A possible reaction mechanism was proposed.
1993, 4(7): 597-600
Abstract:
A new Lycopodium alkaloid huperzine A (1) possesses a potent inhibitory activity of acetylcholinesterase.Six structurally simplified analogues of huperzine A, compound 6, 7, 8, 12,13 and 15, were prepared and the inhibitory activities were evaluated.
A new Lycopodium alkaloid huperzine A (1) possesses a potent inhibitory activity of acetylcholinesterase.Six structurally simplified analogues of huperzine A, compound 6, 7, 8, 12,13 and 15, were prepared and the inhibitory activities were evaluated.
1993, 4(7): 601-602
Abstract:
1, 1'——Bis (benzylseleno) ferrocene and its platinum complex were synthesized.It was found that the platinum complex was efficient catalyst for the hydrosilylation of olefins with triethoxysilane.
1, 1'——Bis (benzylseleno) ferrocene and its platinum complex were synthesized.It was found that the platinum complex was efficient catalyst for the hydrosilylation of olefins with triethoxysilane.
1993, 4(7): 603-604
Abstract:
The MOC reaction over ZrO2/LaF3, CeO2/LaF3 and ThO2/LaF3 catalysts indicated hat these catalysts had high activity and high C2 selectivity at low temperature.In the temperature range 480℃ to 650℃.The methane conversion was 24.4% to 30.8%and the C2 selectivity was 40.0% to 55.4%.The XRD characterization of the catalysts indicated that O2-.and F- exchang happened and LaOF was formed.
The MOC reaction over ZrO2/LaF3, CeO2/LaF3 and ThO2/LaF3 catalysts indicated hat these catalysts had high activity and high C2 selectivity at low temperature.In the temperature range 480℃ to 650℃.The methane conversion was 24.4% to 30.8%and the C2 selectivity was 40.0% to 55.4%.The XRD characterization of the catalysts indicated that O2-.and F- exchang happened and LaOF was formed.
1993, 4(7): 605-608
Abstract:
Two new oligopeptides, Asterin A and B, have been isolated from the roots of Aster tataricus L.f., and their structures were elucidated on the basis of spectroscopic, chemical and enzymatic methods.
Two new oligopeptides, Asterin A and B, have been isolated from the roots of Aster tataricus L.f., and their structures were elucidated on the basis of spectroscopic, chemical and enzymatic methods.
1993, 4(7): 609-610
Abstract:
A novel alkaloid named Hypodemapyrazine was isolated from the whole plant of a fern,Hypodematium sinense Iwatsuki.Its chemical structure has been elucidated to be a novel skeleton containing a hydro-pyrazine by means of UV, IR, 1H-NMR, 13C-NMR and HRMS spectroscopy.
A novel alkaloid named Hypodemapyrazine was isolated from the whole plant of a fern,Hypodematium sinense Iwatsuki.Its chemical structure has been elucidated to be a novel skeleton containing a hydro-pyrazine by means of UV, IR, 1H-NMR, 13C-NMR and HRMS spectroscopy.
1993, 4(7): 611-614
Abstract:
Analytical difficulties encountered in the determination of ethyl carbamate, a known cancinogen, in a wide variety of wines and spirits have been overcome by specific, sensitive GC/GC and CC/CC/MS methods with a relatively shorter extractionprocedure.The lowest detection limits were estimated to be 0.1 and 0.01μg/L for GC/GC and GC/GC/MS respectively.The RSD of the GC/GC method was 2.5%.
Analytical difficulties encountered in the determination of ethyl carbamate, a known cancinogen, in a wide variety of wines and spirits have been overcome by specific, sensitive GC/GC and CC/CC/MS methods with a relatively shorter extractionprocedure.The lowest detection limits were estimated to be 0.1 and 0.01μg/L for GC/GC and GC/GC/MS respectively.The RSD of the GC/GC method was 2.5%.
1993, 4(7): 615-618
Abstract:
In this paper, a new MPT (microwave plasma torch) device has been used as a atomizer for atomic fluorescence spectrometry.Spme elements, such as Zn, Cd, Hg, Pb, As, Co, Mg, Cu, Ag, Mn, Fe have been investigated in detail.
In this paper, a new MPT (microwave plasma torch) device has been used as a atomizer for atomic fluorescence spectrometry.Spme elements, such as Zn, Cd, Hg, Pb, As, Co, Mg, Cu, Ag, Mn, Fe have been investigated in detail.
1993, 4(7): 619-620
Abstract:
NMR microscopy has received great attention from various fields of research, especially material science by its possibility to study materials directly without destruction.Although this technique is almost limited to the detection of fluids constricted in solid samples, such as water in biological systems, solvent diffused in a polymer material1 and liquid saturated rock systems2, the mechanical defects of high elastic rubbers have also been detected3 We are extending this technique to the direct study of the effect of γ-irradiation on cis 1, 4-polybutadiene (PB).This article deals with the investigation of radiation induced crosslinking of PB by NMR microscopy.
NMR microscopy has received great attention from various fields of research, especially material science by its possibility to study materials directly without destruction.Although this technique is almost limited to the detection of fluids constricted in solid samples, such as water in biological systems, solvent diffused in a polymer material1 and liquid saturated rock systems2, the mechanical defects of high elastic rubbers have also been detected3 We are extending this technique to the direct study of the effect of γ-irradiation on cis 1, 4-polybutadiene (PB).This article deals with the investigation of radiation induced crosslinking of PB by NMR microscopy.
1993, 4(7): 621-622
Abstract:
An empirical potential energy function comprising two-and three-body terms, whose parameters have been determiaed from the properties of solid germanium,is used to study the (2×l) reconstruction of the Ge (001) surface.It is found that the formation of a dimer bond lowers the total energy by 0.73eV/atom, as compared to the surface atoms on the ideal Ge (001) surface.
An empirical potential energy function comprising two-and three-body terms, whose parameters have been determiaed from the properties of solid germanium,is used to study the (2×l) reconstruction of the Ge (001) surface.It is found that the formation of a dimer bond lowers the total energy by 0.73eV/atom, as compared to the surface atoms on the ideal Ge (001) surface.
1993, 4(7): 623-624
Abstract:
The optical effects of anion adsorption on silver sol have been studied, It was found that the anion adsorption can make the absorption peak of pure silver sol shifting to longer vevelenngth, which is attributed to the reduction of the free electron density in the surface layer of the silver particle.
The optical effects of anion adsorption on silver sol have been studied, It was found that the anion adsorption can make the absorption peak of pure silver sol shifting to longer vevelenngth, which is attributed to the reduction of the free electron density in the surface layer of the silver particle.
1993, 4(7): 625-626
Abstract:
Surface enhanced Raman scattering of water adsorbed at silver electrodes in very negative potential region was first observed and a simple model related to the adsorption configuration is proposed.
Surface enhanced Raman scattering of water adsorbed at silver electrodes in very negative potential region was first observed and a simple model related to the adsorption configuration is proposed.
1993, 4(7): 627-630
Abstract:
Ultrahigh-molecular-weight polyethylene (UHlMWPE) has been irradiated (0-40 Mrad) with a Co60 source at room temperature under vacuum.Their crystallinity has been investigated by DSC and SAXS A significant increase of heat of fusion can be seen at low irradiation doses, which is attributed to crystallization caused by chain scission during the process of irradiation.It is also observed that thickness of lamellae changes with irradiation dose.Young's modulus has been improved significantly after irradiation at low doses.
Ultrahigh-molecular-weight polyethylene (UHlMWPE) has been irradiated (0-40 Mrad) with a Co60 source at room temperature under vacuum.Their crystallinity has been investigated by DSC and SAXS A significant increase of heat of fusion can be seen at low irradiation doses, which is attributed to crystallization caused by chain scission during the process of irradiation.It is also observed that thickness of lamellae changes with irradiation dose.Young's modulus has been improved significantly after irradiation at low doses.
LOW ENERGY PATHS AND REORIENTATION OF SIDE-GROUPS OF POLYMERS DURING CONFORMATIONAL STATE TRANSITION
1993, 4(7): 631-634
Abstract:
The conformational state transition of polymer chains relates to crystallization processes, migration of the chains in solution, fluctuation of the end-to-end distance of random coils, and the relaxation and phase transitions of polymers.A description of the conformational state transition requires questions about; 1) how many stable conformational states for a specific σ bond; 2) the barriers between the states; 3) the mechanism of the conformational transition; 4) any cooperative behavior during the transition.
The conformational state transition of polymer chains relates to crystallization processes, migration of the chains in solution, fluctuation of the end-to-end distance of random coils, and the relaxation and phase transitions of polymers.A description of the conformational state transition requires questions about; 1) how many stable conformational states for a specific σ bond; 2) the barriers between the states; 3) the mechanism of the conformational transition; 4) any cooperative behavior during the transition.
1993, 4(7): 635-638
Abstract:
Introduction The molecular dynamics simulation technique has recently proved to be a suitable alternative approach for simulation of vibrational spectroscopy.[1-3] In this study, molecular dynamics was utilized to understand low frequency vibrations in highly ordered poly (p-phenylene terephthalmide) (PPTA).A key structural feature of this polymer is the presence of hydrogen bonds.
Introduction The molecular dynamics simulation technique has recently proved to be a suitable alternative approach for simulation of vibrational spectroscopy.[1-3] In this study, molecular dynamics was utilized to understand low frequency vibrations in highly ordered poly (p-phenylene terephthalmide) (PPTA).A key structural feature of this polymer is the presence of hydrogen bonds.
1993, 4(7): 639-640
Abstract:
A vacuum heating operation at 623 K on the surfaces of SiO2-supported promoted ca-talysts makes it possible to reveal the electron transfer from Co and Fe additives to Rhatoms:a Rh catalyst containing 1% Eh under CO exhibits geminal CO IR bands only, while the presence of Co and Fe in promoted Rh catalysts results in linear and bridged CO chemisorptions on Rh in connection with their promotion in the selective hydroformylation of propylene.
A vacuum heating operation at 623 K on the surfaces of SiO2-supported promoted ca-talysts makes it possible to reveal the electron transfer from Co and Fe additives to Rhatoms:a Rh catalyst containing 1% Eh under CO exhibits geminal CO IR bands only, while the presence of Co and Fe in promoted Rh catalysts results in linear and bridged CO chemisorptions on Rh in connection with their promotion in the selective hydroformylation of propylene.
1993, 4(7): 641-644
Abstract:
The complexes[M(CO)3(CH3CN)3] (M=Mo, W) react with an equimolar quantity of PhSnCl3 in dichloromethane at room tempreture to afford new heterobinuclear complexes[PhCl2SnM(Cl)(CO)3(CH3CN)2] [M=Mo (1); W (2)].The complexes react with two equivalents of PR2R'(R=Ph, R'=Ph, Me; R=Cy, R'=H) to yield stablecomplexes[PhCl2SnM(Cl)(CO)3(PR2R')2].Reaction of[PhCl2SnM (Cl) (CO)3(CH3CN)2]with one equivalent of PPh2(CH2)nPPh2(n=I,2) or bulky phosphine ligands PBu2tCl in dichloromethane at room tempreture to give[PhCl2SnMo(Cl)(CO)3{PPh2(CH2)n-PPh2}].CH2Cl2,[PhCl2SnMo(Cl)(CO)3PBu2tCl].CH2Cl2, respectively.The complexes 1 and 2 react with phosphite donor ligands P(OMe)3 to give[PhCl2SnM(Cl)(CO)2-{P(OMe)3}3].All complexes have been characterized by elemental analysis, IR and 1HNMR spectroscopies.Here we report the preliminary results of this work.
The complexes[M(CO)3(CH3CN)3] (M=Mo, W) react with an equimolar quantity of PhSnCl3 in dichloromethane at room tempreture to afford new heterobinuclear complexes[PhCl2SnM(Cl)(CO)3(CH3CN)2] [M=Mo (1); W (2)].The complexes react with two equivalents of PR2R'(R=Ph, R'=Ph, Me; R=Cy, R'=H) to yield stablecomplexes[PhCl2SnM(Cl)(CO)3(PR2R')2].Reaction of[PhCl2SnM (Cl) (CO)3(CH3CN)2]with one equivalent of PPh2(CH2)nPPh2(n=I,2) or bulky phosphine ligands PBu2tCl in dichloromethane at room tempreture to give[PhCl2SnMo(Cl)(CO)3{PPh2(CH2)n-PPh2}].CH2Cl2,[PhCl2SnMo(Cl)(CO)3PBu2tCl].CH2Cl2, respectively.The complexes 1 and 2 react with phosphite donor ligands P(OMe)3 to give[PhCl2SnM(Cl)(CO)2-{P(OMe)3}3].All complexes have been characterized by elemental analysis, IR and 1HNMR spectroscopies.Here we report the preliminary results of this work.
1993, 4(7): 645-648
Abstract:
A series of new complexes of formula Ln2[H2(BAA)2en]3nH2 Otwhere Ln-La,Pr, Eu, Cd, Dy, Er, Yb, n-1-4) have been prepared by the reaccLon of lanthanide ions with acycllc compartmental ligand N, N'-bis(benzoylacetylacetone)ethylenediamine(H4(BAA)2 en) in methanol.IR and UV spectra, as well as TC DAT analysis prove that the ligand and the Lanthanide ions have coordinated.The coordination number is 12 and the complexes may be of double sandwiched structure.
A series of new complexes of formula Ln2[H2(BAA)2en]3nH2 Otwhere Ln-La,Pr, Eu, Cd, Dy, Er, Yb, n-1-4) have been prepared by the reaccLon of lanthanide ions with acycllc compartmental ligand N, N'-bis(benzoylacetylacetone)ethylenediamine(H4(BAA)2 en) in methanol.IR and UV spectra, as well as TC DAT analysis prove that the ligand and the Lanthanide ions have coordinated.The coordination number is 12 and the complexes may be of double sandwiched structure.
1993, 4(7): 649-652
Abstract:
Reaction of 2-pyridone, copper acetate and terbium (or yttrium) perchlorate in acetone with the mole ratio 6:2:1 results in the formation of heteronuclear complex Ln2Cu<、sub>4L8 (HL)4 (OH)2 (ClO4)4 (H20)10 2CH3COCH3(Ln=Tb (1), Y (2)).By recrystallizing (1) in CHCl3 single crystals were obtained and the structure was determined by four-circle diffractometer.Data showed that the crystal is in space group C2/m with a=27.454(9)Å, b=13, 608Å, c=30.556(11)Å, β=99.89(3)°, v=11245.7(7.5)Å3.The structure was solved by a combination of Patterson method and Fourier technique.The final R value is 0.103.In the structure, four copper and two terbium ions are bridged by 2-pyridone anions to form an essentially octahedral Cu4Tb2 core.The terbium atoms are each eight-coordinate and the copper atoms are five-coordinate.
Reaction of 2-pyridone, copper acetate and terbium (or yttrium) perchlorate in acetone with the mole ratio 6:2:1 results in the formation of heteronuclear complex Ln2Cu<、sub>4L8 (HL)4 (OH)2 (ClO4)4 (H20)10 2CH3COCH3(Ln=Tb (1), Y (2)).By recrystallizing (1) in CHCl3 single crystals were obtained and the structure was determined by four-circle diffractometer.Data showed that the crystal is in space group C2/m with a=27.454(9)Å, b=13, 608Å, c=30.556(11)Å, β=99.89(3)°, v=11245.7(7.5)Å3.The structure was solved by a combination of Patterson method and Fourier technique.The final R value is 0.103.In the structure, four copper and two terbium ions are bridged by 2-pyridone anions to form an essentially octahedral Cu4Tb2 core.The terbium atoms are each eight-coordinate and the copper atoms are five-coordinate.
1993, 4(7): 653-656
Abstract:
FTIR spectrum at liquid nitrogen temperature and 1H NMR of air-sensitive polyhydride Ru(H)2(H2)(PPh3)3 have been measured for the first time.It is found that a fluxional process happens at room temperature, but the structure of Ru(H)2(H2)(PPh3)3 with non-equivalent hydrogens is discernible at low temperature.
FTIR spectrum at liquid nitrogen temperature and 1H NMR of air-sensitive polyhydride Ru(H)2(H2)(PPh3)3 have been measured for the first time.It is found that a fluxional process happens at room temperature, but the structure of Ru(H)2(H2)(PPh3)3 with non-equivalent hydrogens is discernible at low temperature.
1993, 4(7): 657-658
Abstract:
The anodic voltammetric curves of heavily doped n-Si in HF solution, on which three different regions have emerged, and were plotted, A porous silicon layer with fine morphology was formed in linear region.
The anodic voltammetric curves of heavily doped n-Si in HF solution, on which three different regions have emerged, and were plotted, A porous silicon layer with fine morphology was formed in linear region.
