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2000 Volume 11 Issue 12
2000, 11(12): 1035-1036
Abstract:
A green synthesis route of diethyl malonate by palladium catalyzed carbonylation of ethyl chloroacetate in the presence of phase transfer agent is carried out under mild conditions in good yield. The effects of reaction temperature and different bases on the yield of diethyl malonate are also discussed.
A green synthesis route of diethyl malonate by palladium catalyzed carbonylation of ethyl chloroacetate in the presence of phase transfer agent is carried out under mild conditions in good yield. The effects of reaction temperature and different bases on the yield of diethyl malonate are also discussed.
2000, 11(12): 1037-1040
Abstract:
In the presence of BiCl3/Al or BiCl3/Fe, in THF-H2O, allylic (benzylic) bromides or α-bromoketones react with diorganyl diselenides to give allylic (benzylic) selenides or α-organylselenocarbonyl compounds respectively in moderate to good yields.
In the presence of BiCl3/Al or BiCl3/Fe, in THF-H2O, allylic (benzylic) bromides or α-bromoketones react with diorganyl diselenides to give allylic (benzylic) selenides or α-organylselenocarbonyl compounds respectively in moderate to good yields.
2000, 11(12): 1041-1044
Abstract:
Reduction of epoxides 1, 2, 3 with LAH and LAH/AlCl3has been studied. The products of reduction with LAH were controlled by steric and stereoelectronic effects. The reduction with LAH/AlCl3seemed to involve an intermediate in which one aluminum ion was shared by both oxygen atoms from the epoxide and the tetrahydrofuran ring.
Reduction of epoxides 1, 2, 3 with LAH and LAH/AlCl3has been studied. The products of reduction with LAH were controlled by steric and stereoelectronic effects. The reduction with LAH/AlCl3seemed to involve an intermediate in which one aluminum ion was shared by both oxygen atoms from the epoxide and the tetrahydrofuran ring.
2000, 11(12): 1045-1048
Abstract:
A mimetic synthesis of a potent acetylcholinesterase inhibitor, Territrem B, was carried out from the naturally occurring jujubosides. The anti-AChE activity of the product, which possesses the 2-en-1-one pharmacophore and the aromatic ring, was measured. The aromatic ring moiety seemed to be less influencing when comparing with the 2-en-1-one moiety.
A mimetic synthesis of a potent acetylcholinesterase inhibitor, Territrem B, was carried out from the naturally occurring jujubosides. The anti-AChE activity of the product, which possesses the 2-en-1-one pharmacophore and the aromatic ring, was measured. The aromatic ring moiety seemed to be less influencing when comparing with the 2-en-1-one moiety.
2000, 11(12): 1049-1052
Abstract:
The synthesis and properties of a class of soluble fluorine-containing aromatic polyimides are described. The polyimides show desirable features of materials for microelectronics applications.
The synthesis and properties of a class of soluble fluorine-containing aromatic polyimides are described. The polyimides show desirable features of materials for microelectronics applications.
2000, 11(12): 1053-1056
Abstract:
The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives were examined. The oxygenation constants of Co(Ⅱ) complexes with crowned bis-Schiff bases were measured and their Mn(Ⅲ) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.
The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives were examined. The oxygenation constants of Co(Ⅱ) complexes with crowned bis-Schiff bases were measured and their Mn(Ⅲ) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.
2000, 11(12): 1057-1060
Abstract:
31P NMR has become a widely applied spectroscopic probe of the structure of phosphorus-containing compounds. Meanwhile, the application of 31P NMR has been rapidly expanded to biochemistry and medicinal chemistry of phosphorus-containing compounds because the growing importance of the phosphorus compounds is now widely realized. We report here the results of 31P NMR study on some phosphorus-containing compounds, namely, O-alkyl O-4-nitrophenyl methyl phosphonates with different alkyl chain-length (MePO-n), 4-nitrophenyl alkylphenylphosphinates with different alkyl chain-length (PhP-n), diethyl phosphono-acetonitrile anion and diethyl phosphite anion. Our results indicate that 31P NMR can not only be applied to not only the study of the hydrolytic reactions of MePO-8 and PhP-8 but also be applied to the study of the presence of the anions of diethylphosphonoacetonitrile and diethyl phosphite in nucleophilic reactions.
31P NMR has become a widely applied spectroscopic probe of the structure of phosphorus-containing compounds. Meanwhile, the application of 31P NMR has been rapidly expanded to biochemistry and medicinal chemistry of phosphorus-containing compounds because the growing importance of the phosphorus compounds is now widely realized. We report here the results of 31P NMR study on some phosphorus-containing compounds, namely, O-alkyl O-4-nitrophenyl methyl phosphonates with different alkyl chain-length (MePO-n), 4-nitrophenyl alkylphenylphosphinates with different alkyl chain-length (PhP-n), diethyl phosphono-acetonitrile anion and diethyl phosphite anion. Our results indicate that 31P NMR can not only be applied to not only the study of the hydrolytic reactions of MePO-8 and PhP-8 but also be applied to the study of the presence of the anions of diethylphosphonoacetonitrile and diethyl phosphite in nucleophilic reactions.
2000, 11(12): 1061-1062
Abstract:
Gnetuhainin P, a new isorhapontigenin dimer, was isolated from the Lianas of Gnetum hainanense C. Y. Cheng. Its structure was established on the basis of spectroscopic evidence, especially 2D NMR techniques.
Gnetuhainin P, a new isorhapontigenin dimer, was isolated from the Lianas of Gnetum hainanense C. Y. Cheng. Its structure was established on the basis of spectroscopic evidence, especially 2D NMR techniques.
2000, 11(12): 1063-1064
Abstract:
A new disaccharide,digobiose 1, was isolated from the rhizomes of Macrothelypteris digophlebia (Bak.) Ching var. elegans (koidz.). Its structure which is very similar with that of sucrose was identified as α-D-glucopyranosyl (1→2')-β-D-sorbopyranoside by spectroscopic analysis.
A new disaccharide,digobiose 1, was isolated from the rhizomes of Macrothelypteris digophlebia (Bak.) Ching var. elegans (koidz.). Its structure which is very similar with that of sucrose was identified as α-D-glucopyranosyl (1→2')-β-D-sorbopyranoside by spectroscopic analysis.
2000, 11(12): 1065-1068
Abstract:
Insignin A, a new C21-steroidal aglycone having the rare 15,16-seco pregnane skeleton was isolated from the acidic hydrolysis part of the 95% EtOH extract of Biondia insignis. It's structure was identified to be 15R,16-epoxy-3β,14β,16β-trihydroxy-15,16-secopregn-5-ene-20-one based on the spectral data.
Insignin A, a new C21-steroidal aglycone having the rare 15,16-seco pregnane skeleton was isolated from the acidic hydrolysis part of the 95% EtOH extract of Biondia insignis. It's structure was identified to be 15R,16-epoxy-3β,14β,16β-trihydroxy-15,16-secopregn-5-ene-20-one based on the spectral data.
2000, 11(12): 1069-1072
Abstract:
From the petroleum part of the 70% acetone extract of Coleus xanthanthus, two new abietane diterpenoids have been isolated and identified as 11-acetoxy-coleon U(1) and 11,16-diacetoxy-coleon U(2).Their structures were elucidated with spectral methods.
From the petroleum part of the 70% acetone extract of Coleus xanthanthus, two new abietane diterpenoids have been isolated and identified as 11-acetoxy-coleon U(1) and 11,16-diacetoxy-coleon U(2).Their structures were elucidated with spectral methods.
2000, 11(12): 1073-1076
Abstract:
(+)-Sesamin was found in Semen Cuscutae for the first time. A rapid and simple approach for the analysis of (+)-sesamin in different sources of Semen Cuscutae is proposed, which used GC-FID for the determination of (+)-sesamin and GC-MS for its identification. The result suggested that this approach could be used to identify Semen Cuscutae from various sources based on the different content of (+)-sesamin in them.
(+)-Sesamin was found in Semen Cuscutae for the first time. A rapid and simple approach for the analysis of (+)-sesamin in different sources of Semen Cuscutae is proposed, which used GC-FID for the determination of (+)-sesamin and GC-MS for its identification. The result suggested that this approach could be used to identify Semen Cuscutae from various sources based on the different content of (+)-sesamin in them.
2000, 11(12): 1077-1080
Abstract:
3,3'-Dioxo-1,1'(3H,3'H)spirobi[isobenzofuran]-5,6,5',6'-tetracarboxylic acid 1 was resolved successfully and the corresponding optically active polyimides PI were synthesized. The properties of the optically active PI and the racemic one were investigated. The results showed that the specific rotation of (-)-PI was about two times to that of the (+)-PI, and the regularity of the optically active PI was higher than that of the racemic one.
3,3'-Dioxo-1,1'(3H,3'H)spirobi[isobenzofuran]-5,6,5',6'-tetracarboxylic acid 1 was resolved successfully and the corresponding optically active polyimides PI were synthesized. The properties of the optically active PI and the racemic one were investigated. The results showed that the specific rotation of (-)-PI was about two times to that of the (+)-PI, and the regularity of the optically active PI was higher than that of the racemic one.
2000, 11(12): 1081-1084
Abstract:
p-Hydrazinobenzenesulfonic acid is explored as a novel ultraviolet labeling reagent for capillary electrophoresis (CE) of mono-and disaccharides. The labeling reaction takes less than 10 minutes and introduces both of absorption and charge groups into the sugars.
p-Hydrazinobenzenesulfonic acid is explored as a novel ultraviolet labeling reagent for capillary electrophoresis (CE) of mono-and disaccharides. The labeling reaction takes less than 10 minutes and introduces both of absorption and charge groups into the sugars.
2000, 11(12): 1085-1088
Abstract:
Self-assembled monolayers of octadecanethiol (ODT) on gold have been studied by electrochemical impedance spectroscopy (EIS). The fractional coverage has been examined as a function of immersion time of Au in ODT deposition solution. The fractional coverage exhibits two distinct adsorption steps:an initial rapid step followed by a slow one. The fractional coverage of ODT monolayer increases sharply from zero to more than 99% of its maximum within the first minute. However, it takes a day for the fractional coverage to approach its final value.
Self-assembled monolayers of octadecanethiol (ODT) on gold have been studied by electrochemical impedance spectroscopy (EIS). The fractional coverage has been examined as a function of immersion time of Au in ODT deposition solution. The fractional coverage exhibits two distinct adsorption steps:an initial rapid step followed by a slow one. The fractional coverage of ODT monolayer increases sharply from zero to more than 99% of its maximum within the first minute. However, it takes a day for the fractional coverage to approach its final value.
2000, 11(12): 1089-1092
Abstract:
A molecular vector-type descriptor containing 6 variables is used to describe the structure of aromatic hydrocarbons (AHs) and relate to normal boiling points (bp) of AHs. The correlation coefficient (R) between the estimated bp and experimental bp is 0.9988 and the root mean square error (RMS) is 7.907℃ for 66 AHs. The RMS obtained by cross-validation is 9.131℃, which implies the relationship model having good prediction ability.
A molecular vector-type descriptor containing 6 variables is used to describe the structure of aromatic hydrocarbons (AHs) and relate to normal boiling points (bp) of AHs. The correlation coefficient (R) between the estimated bp and experimental bp is 0.9988 and the root mean square error (RMS) is 7.907℃ for 66 AHs. The RMS obtained by cross-validation is 9.131℃, which implies the relationship model having good prediction ability.
2000, 11(12): 1093-1094
Abstract:
Small angle X-ray scattering (SAXS) was used to study the effect of dissolved CO2 on the conformation of polystyrene (PS) in PS/tetrahydrofuran(THF) solution at 308.15 K and at pressures up to 3 MPa. The cloud pressure and the expansion curve of the solution were also determined. The dependence of the conformation on pressure was discussed.
Small angle X-ray scattering (SAXS) was used to study the effect of dissolved CO2 on the conformation of polystyrene (PS) in PS/tetrahydrofuran(THF) solution at 308.15 K and at pressures up to 3 MPa. The cloud pressure and the expansion curve of the solution were also determined. The dependence of the conformation on pressure was discussed.
2000, 11(12): 1095-1096
Abstract:
The critical micelle concentrations (CMC) and the micelle-forming enthalpies (△Hmic) of gemini surfactants were first measured by the precise titration microcalorimetry. The results showed that △Hmicvalues are negative, and there is an exothermal minimum between s=4 and s=6. Furthermore, the CMCs of the surfactants are in good agreement with literature values.
The critical micelle concentrations (CMC) and the micelle-forming enthalpies (△Hmic) of gemini surfactants were first measured by the precise titration microcalorimetry. The results showed that △Hmicvalues are negative, and there is an exothermal minimum between s=4 and s=6. Furthermore, the CMCs of the surfactants are in good agreement with literature values.
2000, 11(12): 1097-1100
Abstract:
Soluble Poly(propargyl benzoate) (PPBT) with π-conjugated structure was synthesized using a novel bis(triphenylphosphine)-bisacetylide palladium complex catalyst[Pd(PPh3)2(C≡CCH2OOCPh)2] (PPB). An interdigital gold electrode was covered by screen printing films of doped PPBT (DPPBT) to prepare a resistance-type humidity sensor, which exhibits electrical response towards relative humidity (RH%) variations in the range 11%-96%. PPBT shows promise as a new humidity-sensitive material.
Soluble Poly(propargyl benzoate) (PPBT) with π-conjugated structure was synthesized using a novel bis(triphenylphosphine)-bisacetylide palladium complex catalyst[Pd(PPh3)2(C≡CCH2OOCPh)2] (PPB). An interdigital gold electrode was covered by screen printing films of doped PPBT (DPPBT) to prepare a resistance-type humidity sensor, which exhibits electrical response towards relative humidity (RH%) variations in the range 11%-96%. PPBT shows promise as a new humidity-sensitive material.
2000, 11(12): 1101-1102
Abstract:
The kinetic behavior of forming the iso-nuclear β-type chelates of rare earth ions (RE3+) with p-sulphoaminobromophosphonazo (BPA-pSN) in ClCH2 COOH-CH3 COONa buffer solutions were studied by a spectrophotometric method.
The kinetic behavior of forming the iso-nuclear β-type chelates of rare earth ions (RE3+) with p-sulphoaminobromophosphonazo (BPA-pSN) in ClCH2 COOH-CH3 COONa buffer solutions were studied by a spectrophotometric method.
2000, 11(12): 1103-1106
Abstract:
Perovskite-type La1-x Srx MO3-δ (x=0,0.1,0.2, B=Co,Fe,Mn) oxides were prepared by pyrolysis of metal salt-(organic acid)-cellulose compound precursors. Low calcination temperatures, usually lower than 600℃, were needed. The specific surface area of the as-prepared oxides is higher than that prepared by the cellulose adsorption method, and is comparable to that prepared by sol-gel method. The effective organic acid could be EDTA acid, citric acid or DL-hydroxysuccinic acid, among them, EDTA acid is the best one.
Perovskite-type La1-x Srx MO3-δ (x=0,0.1,0.2, B=Co,Fe,Mn) oxides were prepared by pyrolysis of metal salt-(organic acid)-cellulose compound precursors. Low calcination temperatures, usually lower than 600℃, were needed. The specific surface area of the as-prepared oxides is higher than that prepared by the cellulose adsorption method, and is comparable to that prepared by sol-gel method. The effective organic acid could be EDTA acid, citric acid or DL-hydroxysuccinic acid, among them, EDTA acid is the best one.
2000, 11(12): 1107-1110
Abstract:
High-quality mesoporous silica MCM-48 were synthesized under basic conditions by using the mixture of cetyltrimethylammonium bromide (CTAB) and alkylamine (Cn NH2n+3, n=8,10,12,14, respectively) as templates. The effects of the alkylamines with different chain lengths (n=8,10,12,14,16,18, respectively) on the silica structure were investigated.
High-quality mesoporous silica MCM-48 were synthesized under basic conditions by using the mixture of cetyltrimethylammonium bromide (CTAB) and alkylamine (Cn NH2n+3, n=8,10,12,14, respectively) as templates. The effects of the alkylamines with different chain lengths (n=8,10,12,14,16,18, respectively) on the silica structure were investigated.
2000, 11(12): 1111-1112
Abstract:
Valence of elements in HgBa2Can-1CunO2n+2+δ(n=1, 2, 3, 4) (both argon and oxygen annealed samples) were calculated. The result indicated for both argon and oxygen annealed samples, Hg had the lowest valence for the highest Tc sample. For fixed n, the valence of Cu in oxygen annealed samples was larger than that in argon annealed samples, indicating that oxygen annealed samples produce more carriers than argon annealed samples.
Valence of elements in HgBa2Can-1CunO2n+2+δ(n=1, 2, 3, 4) (both argon and oxygen annealed samples) were calculated. The result indicated for both argon and oxygen annealed samples, Hg had the lowest valence for the highest Tc sample. For fixed n, the valence of Cu in oxygen annealed samples was larger than that in argon annealed samples, indicating that oxygen annealed samples produce more carriers than argon annealed samples.
