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1996 Volume 7 Issue 9
1996, 7(9): 785-787
Abstract:
Nine copper compounds are used for catalyzing the cyclopropanation of l-hexene/TME with alkyl diazoacetate. Cu (Salad) 2 shows the highest yield for the reaction of TME at high temperature such as 100℃. The reaction of crude RDA with TME in 73.7% yield under the optimal condition is obtained.
Nine copper compounds are used for catalyzing the cyclopropanation of l-hexene/TME with alkyl diazoacetate. Cu (Salad) 2 shows the highest yield for the reaction of TME at high temperature such as 100℃. The reaction of crude RDA with TME in 73.7% yield under the optimal condition is obtained.
1996, 7(9): 788-789
Abstract:
α, β-Unsaturated amides with various substitution patterns at the carbon-carbon double bond and nitrogen atom can be reduced to the corresponding saturated amides with high selectivity and yields with NaBH4/BiCl3 system.
α, β-Unsaturated amides with various substitution patterns at the carbon-carbon double bond and nitrogen atom can be reduced to the corresponding saturated amides with high selectivity and yields with NaBH4/BiCl3 system.
1996, 7(9): 790-793
Abstract:
The reactions of several phenols with 2, 2, 6, 6-tetramethyl-4-methoxypi-peridine oxoammonium chloride were studied. It was found that this oxoammonium salt is a facile reagent for the oxidative coupling of phenols, o-substituted phenols gave the para-para-coupling products and p-substituted phenols gave the ortho-ortho-coupling products, while o-, p-substituted phenol gave the corresponding dehydrogenated coupling product.
The reactions of several phenols with 2, 2, 6, 6-tetramethyl-4-methoxypi-peridine oxoammonium chloride were studied. It was found that this oxoammonium salt is a facile reagent for the oxidative coupling of phenols, o-substituted phenols gave the para-para-coupling products and p-substituted phenols gave the ortho-ortho-coupling products, while o-, p-substituted phenol gave the corresponding dehydrogenated coupling product.
1996, 7(9): 794-796
Abstract:
Several triplet sensitizers were found to be able to photosensitize cycloreversion of the photodimer (1) of methyl naphthalene-2-carboxylate. With the increase of the donor's triplet energy, the quantum yield of the isomerization is increased. The cycloreversion mechanism of 1 was suggested to proceed via triplet energy transfer.
Several triplet sensitizers were found to be able to photosensitize cycloreversion of the photodimer (1) of methyl naphthalene-2-carboxylate. With the increase of the donor's triplet energy, the quantum yield of the isomerization is increased. The cycloreversion mechanism of 1 was suggested to proceed via triplet energy transfer.
1996, 7(9): 797-798
Abstract:
Cu2O-Catalyzed reaction of isocyanoacetate with l-oxoalkylphosphonatrs afforded predominantly Z-α-formylamino-β-phosphoryl-α, β-alkenoate.
Cu2O-Catalyzed reaction of isocyanoacetate with l-oxoalkylphosphonatrs afforded predominantly Z-α-formylamino-β-phosphoryl-α, β-alkenoate.
1996, 7(9): 799-800
Abstract:
A series of 1, 2-cyclic monoalkyl-rac-glycerothiophosphates of 2', 3'-O-isopropylideneuridine were synthesized in a one-pot procedure in overall yields of 36-40% by means of hexaethylphosphorous triamide as phosphorylating reagent.
A series of 1, 2-cyclic monoalkyl-rac-glycerothiophosphates of 2', 3'-O-isopropylideneuridine were synthesized in a one-pot procedure in overall yields of 36-40% by means of hexaethylphosphorous triamide as phosphorylating reagent.
1996, 7(9): 801-802
Abstract:
(±)-Deoxyschisandrin 1 and the corresponding trans-isomer 2 were readily prepared by intramolecular oxidative coupling of 1.4-diaryl-2.3-dimethylbutanes 7 and 6 with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) in trifluoroacetic acid (TFA).
(±)-Deoxyschisandrin 1 and the corresponding trans-isomer 2 were readily prepared by intramolecular oxidative coupling of 1.4-diaryl-2.3-dimethylbutanes 7 and 6 with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) in trifluoroacetic acid (TFA).
1996, 7(9): 803-806
Abstract:
Substituted imidazolinium salt, l, 2-dimethyl-3-(p-methoxybenzenesulfonyl) imidazolinium iodide, as a tetrahydrofolate model in terms of the ability to transfer a substituted one-carbon unit (ethylidyne, nitromethylethylidene), can react with a variety of mono- and bifunctional nucleophiles and lead to some carboline alkaloids and other heterocyclic compounds.
Substituted imidazolinium salt, l, 2-dimethyl-3-(p-methoxybenzenesulfonyl) imidazolinium iodide, as a tetrahydrofolate model in terms of the ability to transfer a substituted one-carbon unit (ethylidyne, nitromethylethylidene), can react with a variety of mono- and bifunctional nucleophiles and lead to some carboline alkaloids and other heterocyclic compounds.
1996, 7(9): 807-808
Abstract:
The amphiphilic derivatives of 8-hydroquinoline with alkyl chain have been synthesized. These derivatives can form stable monolayer on pure water and an aqueous subphase containing metal ions.
The amphiphilic derivatives of 8-hydroquinoline with alkyl chain have been synthesized. These derivatives can form stable monolayer on pure water and an aqueous subphase containing metal ions.
1996, 7(9): 809-811
Abstract:
Two peptides (LI22 and LI29) designed to form four-helix bundle were synthesized by stepwise solid phase peptide synthesis (SPPS) using Fmoc strategy, purified by reversed phase high performance liquid chromatography (HPLC) and confirmed by fast atom bombardment mass spectrum (FABMS).
Two peptides (LI22 and LI29) designed to form four-helix bundle were synthesized by stepwise solid phase peptide synthesis (SPPS) using Fmoc strategy, purified by reversed phase high performance liquid chromatography (HPLC) and confirmed by fast atom bombardment mass spectrum (FABMS).
1996, 7(9): 812-815
Abstract:
As an attempt to find out how the sequence length determine the α-helix formation, seven peptides containing 2 to 4 heptad repeats (16-29 residues long) were designed and characterized. Results of circular dichroism (CD) show that two-heptad repeats are not long enough to form highly helical structure, while more than three are adequate, in aqueous solution.
As an attempt to find out how the sequence length determine the α-helix formation, seven peptides containing 2 to 4 heptad repeats (16-29 residues long) were designed and characterized. Results of circular dichroism (CD) show that two-heptad repeats are not long enough to form highly helical structure, while more than three are adequate, in aqueous solution.
1996, 7(9): 816-817
Abstract:
Two new diterpenoids, named isodoternifolins A (1) and B (2), together with seven known compounds were isolated from the ethanol extract of dried stems and leaves of Isodon temifolius (D. Don) Kudo. The structures of 1 and 2 were determined as 7β-hydroxy-6β, 11α, 15β-triacetoxy-7α, 20-epoxy-entkaur-16-ene and 6β, 7β, 15β-trihydroxy-11α-acetoxy-7α, 20-epoxy-entkaur-16-ene by chemical and spectral evidence respectively.
Two new diterpenoids, named isodoternifolins A (1) and B (2), together with seven known compounds were isolated from the ethanol extract of dried stems and leaves of Isodon temifolius (D. Don) Kudo. The structures of 1 and 2 were determined as 7β-hydroxy-6β, 11α, 15β-triacetoxy-7α, 20-epoxy-entkaur-16-ene and 6β, 7β, 15β-trihydroxy-11α-acetoxy-7α, 20-epoxy-entkaur-16-ene by chemical and spectral evidence respectively.
1996, 7(9): 818-819
Abstract:
A very sensitive electrochemical procedure for trace determination of copper and tin in the presence of lead using cathodic adsorption voltammetry is presented. The complex of copper, tin with salicylfluorone (SAF) is adsorbed on the hanging mercury drop electrode (HMDE) and the reduction current of the accumulated complex is measured by voltammetry. This method achieves the simultaneous determination of copper and tin, and has been applied to determine canned food.
A very sensitive electrochemical procedure for trace determination of copper and tin in the presence of lead using cathodic adsorption voltammetry is presented. The complex of copper, tin with salicylfluorone (SAF) is adsorbed on the hanging mercury drop electrode (HMDE) and the reduction current of the accumulated complex is measured by voltammetry. This method achieves the simultaneous determination of copper and tin, and has been applied to determine canned food.
1996, 7(9): 820-822
Abstract:
Fura-2 was first used to monitor intracellular RE3+. The characterizations of RE3+-Fura-2 interactions in solutions simulating intracellular ionic composition show that La3+ and Y3+ both form 1:1 RE3+-fura-2 complexes. The apparent dissociation constants are 1.61×10-7M, and 4.04×10-7M, respectively. The mouse myeloma (SP2/0) cells exposed to free RE3+ or free RE3+ and some small molecules in body were studied by single cell cation measurement system. The results support the assumption that RE3+ ions cannot enter the cytoplasm of living cells, and the small molecules used in our experiments couldn't improve the permeability of RE3+ ions.
Fura-2 was first used to monitor intracellular RE3+. The characterizations of RE3+-Fura-2 interactions in solutions simulating intracellular ionic composition show that La3+ and Y3+ both form 1:1 RE3+-fura-2 complexes. The apparent dissociation constants are 1.61×10-7M, and 4.04×10-7M, respectively. The mouse myeloma (SP2/0) cells exposed to free RE3+ or free RE3+ and some small molecules in body were studied by single cell cation measurement system. The results support the assumption that RE3+ ions cannot enter the cytoplasm of living cells, and the small molecules used in our experiments couldn't improve the permeability of RE3+ ions.
1996, 7(9): 823-824
Abstract:
A gel permeation chromatographic method using cross-linked dextran G-50 was employed to determine the speciation of magnesium (Ⅱ) in albumen. It has been found that 0.22% of magnesium (Ⅱ) in albumen combines with proteins and the rest exists as free ions and small-molecular complexes.
A gel permeation chromatographic method using cross-linked dextran G-50 was employed to determine the speciation of magnesium (Ⅱ) in albumen. It has been found that 0.22% of magnesium (Ⅱ) in albumen combines with proteins and the rest exists as free ions and small-molecular complexes.
1996, 7(9): 825-828
Abstract:
The electrochemical reaction mechanism of Vitamin B2 on platinum electrode in acid aqueous solution has been studied by thin layer cyclic voltammetry (TLCV) and thin layer spectroelectrochemistry (TLSEC). The results indicate that there is a redox process of VB2 via a semiquinone radical to dihydroflavin. The radical intermediate has been detected by in-situ UVSEC method for the first time.
The electrochemical reaction mechanism of Vitamin B2 on platinum electrode in acid aqueous solution has been studied by thin layer cyclic voltammetry (TLCV) and thin layer spectroelectrochemistry (TLSEC). The results indicate that there is a redox process of VB2 via a semiquinone radical to dihydroflavin. The radical intermediate has been detected by in-situ UVSEC method for the first time.
1996, 7(9): 829-830
Abstract:
Synthesis of polysiloxane with N-decanyltartrimide moieties and its application in coated capillary electrophoresis are reported.
Synthesis of polysiloxane with N-decanyltartrimide moieties and its application in coated capillary electrophoresis are reported.
1996, 7(9): 831-834
Abstract:
A high speed data sampling system on dynamic Oscillographic analysis was established with a 80386DX40 computer, AD 674 and flow injection system. Programs were designed in Microsoft Windows 3.1, that can process E-t, dE/dt-t, i'f-t and other kinds of curve on oscillographic analysis. A satisfactory result on determination of Pb2+ and Cd2+ was obtained.
A high speed data sampling system on dynamic Oscillographic analysis was established with a 80386DX40 computer, AD 674 and flow injection system. Programs were designed in Microsoft Windows 3.1, that can process E-t, dE/dt-t, i'f-t and other kinds of curve on oscillographic analysis. A satisfactory result on determination of Pb2+ and Cd2+ was obtained.
1996, 7(9): 835-836
Abstract:
An electrochemical probe measurement system for detecting an electrogenerated etchant in solution is developed. Concentration distribution of electrogenerated etchant bromine as close as 8 micrometer to the surface of macrodisk is studied quantitatively.
An electrochemical probe measurement system for detecting an electrogenerated etchant in solution is developed. Concentration distribution of electrogenerated etchant bromine as close as 8 micrometer to the surface of macrodisk is studied quantitatively.
1996, 7(9): 837-840
Abstract:
It was found that the polarographic reduction wave of hemolysin in phosphate buffer solution was closely related to its biological activity. According to the various effects of drugs on the formation of hemolysin antibody, a new method for screening immune drugs was established.
It was found that the polarographic reduction wave of hemolysin in phosphate buffer solution was closely related to its biological activity. According to the various effects of drugs on the formation of hemolysin antibody, a new method for screening immune drugs was established.
1996, 7(9): 841-844
Abstract:
For zeolite-catalyzed Friedel-Crafts acylation of aromatic rings, the Lewis acid sites were found to be active;while the Bronsted acid sites with moderate strength were found to be inactive.
For zeolite-catalyzed Friedel-Crafts acylation of aromatic rings, the Lewis acid sites were found to be active;while the Bronsted acid sites with moderate strength were found to be inactive.
1996, 7(9): 845-846
Abstract:
Catalytic dechlorination of 1-chloronaphthalene (Ⅰ), 2-chloronaph-thalene (Ⅱ), o-chlorobiphenyl (Ⅲ), m-chlorobiphenyl (Ⅳ), p-chlorobiphenyl (Ⅴ) 1-chloroanthracene (Ⅵ) and 2-chloroanthracene (Ⅶ) has been studied with dicyclopentadienyl yttrium/NaH system. The dechlorination products for (Ⅰ), (Ⅱ), (Ⅲ), (Ⅳ) and (Ⅴ) are corresponding aromatics in excellent yields. However for (Ⅵ) and (Ⅶ), the dechlorination products are mixed aromatics.
Catalytic dechlorination of 1-chloronaphthalene (Ⅰ), 2-chloronaph-thalene (Ⅱ), o-chlorobiphenyl (Ⅲ), m-chlorobiphenyl (Ⅳ), p-chlorobiphenyl (Ⅴ) 1-chloroanthracene (Ⅵ) and 2-chloroanthracene (Ⅶ) has been studied with dicyclopentadienyl yttrium/NaH system. The dechlorination products for (Ⅰ), (Ⅱ), (Ⅲ), (Ⅳ) and (Ⅴ) are corresponding aromatics in excellent yields. However for (Ⅵ) and (Ⅶ), the dechlorination products are mixed aromatics.
1996, 7(9): 847-848
Abstract:
PdCl2 (TPPTS) 2 exhibits very high catalytic activity for carbonylation of allyl chloride in aq. NaOH/toluene two-phase medium under atmospheric pressure. The average turnover frequency (TOFav, mol substrate/mol Pd·min) reaches 31 min-1.
PdCl2 (TPPTS) 2 exhibits very high catalytic activity for carbonylation of allyl chloride in aq. NaOH/toluene two-phase medium under atmospheric pressure. The average turnover frequency (TOFav, mol substrate/mol Pd·min) reaches 31 min-1.
1996, 7(9): 849-852
Abstract:
The catalysts were prepared by the temperature programmed reaction (TPR) of MoO3 with NH3 at various temperatures in the range of 573K~973K, and their hydrodenitrogenation (HDN) activities were tested in situ. It is shown that molybdenum nitride (Mo2N) was formed above 923K and its intermediate MoO2 formed at about 573~623K under the rapid (5K/min. ) TPR conditions. Mo2N is the most active species for pyridine HDN among MoO3, MoO2, MoS2, and Mo2N. Moreover, it can be promoted by adding Ni component. It is shown that the Ni/Mo2N catalyst prepared by adding some NiO into the precursor MoO3 has a steady HDN activity which is far higher than that of the commercial sulfided NiMo/Al2O3 (HR346) catalyst.
The catalysts were prepared by the temperature programmed reaction (TPR) of MoO3 with NH3 at various temperatures in the range of 573K~973K, and their hydrodenitrogenation (HDN) activities were tested in situ. It is shown that molybdenum nitride (Mo2N) was formed above 923K and its intermediate MoO2 formed at about 573~623K under the rapid (5K/min. ) TPR conditions. Mo2N is the most active species for pyridine HDN among MoO3, MoO2, MoS2, and Mo2N. Moreover, it can be promoted by adding Ni component. It is shown that the Ni/Mo2N catalyst prepared by adding some NiO into the precursor MoO3 has a steady HDN activity which is far higher than that of the commercial sulfided NiMo/Al2O3 (HR346) catalyst.
1996, 7(9): 853-854
Abstract:
Dimerization constant of 6-O-benzoyl-β-CD, which is insoluble in water, was determined for the first time by a calculation method involving an approximation step as well as a geometric step. This calculation method can be applied to other functionally modified cyclodextrin host compounds.
Dimerization constant of 6-O-benzoyl-β-CD, which is insoluble in water, was determined for the first time by a calculation method involving an approximation step as well as a geometric step. This calculation method can be applied to other functionally modified cyclodextrin host compounds.
1996, 7(9): 855-858
Abstract:
The improved beam sources CO (a, v≤4) and CO (a, v≤3) are produced in a beam-gas experiment by collision of CO2 with He (22 S) and Ar (3P0, 2) respectively. The energy transfer reaction of CO (a) with NO (x) mainly give NO (A, v). The vibrational distribution of CO (a) has a considerable effect on that of NO (A, v) and the vibrational distributions of NO (A, v) follow the energy gap law and the Franck-Condon (F-C) principle.
The improved beam sources CO (a, v≤4) and CO (a, v≤3) are produced in a beam-gas experiment by collision of CO2 with He (22 S) and Ar (3P0, 2) respectively. The energy transfer reaction of CO (a) with NO (x) mainly give NO (A, v). The vibrational distribution of CO (a) has a considerable effect on that of NO (A, v) and the vibrational distributions of NO (A, v) follow the energy gap law and the Franck-Condon (F-C) principle.
1996, 7(9): 859-861
Abstract:
The oligomer approach used in geometry optimization for two dimensional polymers and crystals has been developed. Geometry optimization for planar π-conjugated system, graphite, with the oligomer approach has been performed at AM1 level and the result is in good agreement with the experimental.
The oligomer approach used in geometry optimization for two dimensional polymers and crystals has been developed. Geometry optimization for planar π-conjugated system, graphite, with the oligomer approach has been performed at AM1 level and the result is in good agreement with the experimental.
1996, 7(9): 862-863
Abstract:
The stability constants of the 1:1 complexes of H4L (5.12-diphenyl-7, 14-dimethyl-1, 4, 8.11-tetraazamacroeyclotetradecane-N', N", N"', N""-tetraacetic acid) with M2- ions (M=Cu, Ni, Co, Zn, Mn, Cd, Mg, Ca, Sr, Ba) were determined in 0.5 mol L KCl aqueous solution at 45℃, 50℃ and 60℃ by potentiometric titration and computer fitting. The △H and △S of the coordination reaction in the solution were given.
The stability constants of the 1:1 complexes of H4L (5.12-diphenyl-7, 14-dimethyl-1, 4, 8.11-tetraazamacroeyclotetradecane-N', N", N"', N""-tetraacetic acid) with M2- ions (M=Cu, Ni, Co, Zn, Mn, Cd, Mg, Ca, Sr, Ba) were determined in 0.5 mol L KCl aqueous solution at 45℃, 50℃ and 60℃ by potentiometric titration and computer fitting. The △H and △S of the coordination reaction in the solution were given.
1996, 7(9): 864-867
Abstract:
14-Membered macrocyclic dioxotetraamines deprotonate stepwisely upon coordination to cupric ions. Singly- and doubly-deprotonated complexes are the main species. While for 13-membered analogs, non- and doubly-deprotonated complexes are the main species.
14-Membered macrocyclic dioxotetraamines deprotonate stepwisely upon coordination to cupric ions. Singly- and doubly-deprotonated complexes are the main species. While for 13-membered analogs, non- and doubly-deprotonated complexes are the main species.
1996, 7(9): 868-871
Abstract:
The supramolecular inclusion complex of Fe-tetrakis (sulfophenyf)-porphine (FeTPPS4) with β-cyclodextrin (β-CD) cross-linking polymer (β-CDP) was used as an analogue for peroxide proteinase. The immobilized inclusion complex was found to exhibit high proteinase-like activity, which has been demonstrated by enzymatic methods of hydrogen peroxide.
The supramolecular inclusion complex of Fe-tetrakis (sulfophenyf)-porphine (FeTPPS4) with β-cyclodextrin (β-CD) cross-linking polymer (β-CDP) was used as an analogue for peroxide proteinase. The immobilized inclusion complex was found to exhibit high proteinase-like activity, which has been demonstrated by enzymatic methods of hydrogen peroxide.
1996, 7(9): 872-874
Abstract:
It is indicative of the TSR result that CH4 was strongly adsorbed on well degassed SrCO3 surface at high temperature. A desorption peak of CH4 was found in CH4-TPD profile which appeared at ca. 310℃. The strong adsorption of CH4 over the surface of SrCO3 was attributed to the strong basicity of SrO sites resulted from decomposition of SrCO3.
It is indicative of the TSR result that CH4 was strongly adsorbed on well degassed SrCO3 surface at high temperature. A desorption peak of CH4 was found in CH4-TPD profile which appeared at ca. 310℃. The strong adsorption of CH4 over the surface of SrCO3 was attributed to the strong basicity of SrO sites resulted from decomposition of SrCO3.
1996, 7(9): 875-878
Abstract:
BAM and π-A isotherms were used to study the interaction between cetyltrimethylammonium bromide (CTAB) and polyacrylamide with various hydrolysis degree (HPAM). Viscosity and Zeta-potential measurements were employed to investigate the properties of PAM solution. In order to explain the experimental results. we supposed that a comblike complex, which is surface active, was formed between CTAB and HPAM.
BAM and π-A isotherms were used to study the interaction between cetyltrimethylammonium bromide (CTAB) and polyacrylamide with various hydrolysis degree (HPAM). Viscosity and Zeta-potential measurements were employed to investigate the properties of PAM solution. In order to explain the experimental results. we supposed that a comblike complex, which is surface active, was formed between CTAB and HPAM.
