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1998 Volume 9 Issue 8
1998, 9(8): 697-698
Abstract:
1,3-Propanediol, 1,4-butanediol or 1,5-pentanediol reacts with magnesium to form corresponding magnesium alkoxides, which eliminate water with the formation of cyclic ethers and, respectively, allyl alcohol, 3-buten-l-ol and 4-penten-l-ol.
1,3-Propanediol, 1,4-butanediol or 1,5-pentanediol reacts with magnesium to form corresponding magnesium alkoxides, which eliminate water with the formation of cyclic ethers and, respectively, allyl alcohol, 3-buten-l-ol and 4-penten-l-ol.
Conjugate Addition Reactions of Functionalized Organozinc-copper Reagents to α, β-Unsaturated Esters
1998, 9(8): 699-700
Abstract:
Functionalized organozic reagents can easily conduct 1,4-addition reaction with unsaturated esters in the persence of Cu(OAc)2 and LiCI under very mild conditions to give the products in excellent yields.
Functionalized organozic reagents can easily conduct 1,4-addition reaction with unsaturated esters in the persence of Cu(OAc)2 and LiCI under very mild conditions to give the products in excellent yields.
1998, 9(8): 701-704
Abstract:
In order to investigate the reaction mechanism of intramolecular C-H insertion by Rh(Ⅱ)-mediated carbenoids with rrans-(2-phenylcyclopropyl)carbinal radical as the mechanistic probe, diazo compounds 2-(2-phenylcyclopropyl)ethyl diazoacetoacetate 8a and methyl 2-diazo-3-oxo-6-(2-phenylcyclopropyl)hexanoate 8b have been synthesized. Preliminary investigation of the intramolecular C-H insertion with Rh2(OAc)4 as catalyst supports a concerted insertion process.
In order to investigate the reaction mechanism of intramolecular C-H insertion by Rh(Ⅱ)-mediated carbenoids with rrans-(2-phenylcyclopropyl)carbinal radical as the mechanistic probe, diazo compounds 2-(2-phenylcyclopropyl)ethyl diazoacetoacetate 8a and methyl 2-diazo-3-oxo-6-(2-phenylcyclopropyl)hexanoate 8b have been synthesized. Preliminary investigation of the intramolecular C-H insertion with Rh2(OAc)4 as catalyst supports a concerted insertion process.
1998, 9(8): 705-706
Abstract:
2, 3, 3a, 4, 5, 9b-hexahydro-8-(N-methylsulfamylmethyl)-4-phenylfuro[3, 2-c]quinoline was obtained when the alkylation of compound 1 was carried out with THF as solvent. The structure of the product was determined and the mechanism of the reaction was studied and proved by the imitation reaction.
2, 3, 3a, 4, 5, 9b-hexahydro-8-(N-methylsulfamylmethyl)-4-phenylfuro[3, 2-c]quinoline was obtained when the alkylation of compound 1 was carried out with THF as solvent. The structure of the product was determined and the mechanism of the reaction was studied and proved by the imitation reaction.
1998, 9(8): 707-710
Abstract:
A number of tetrahydroprotoberberines with electron-withdrawing groups on ring D have been synthesized via photocyclization of 2-formyl-1 -benzylideneisoquinoline enamides as the key step.
A number of tetrahydroprotoberberines with electron-withdrawing groups on ring D have been synthesized via photocyclization of 2-formyl-1 -benzylideneisoquinoline enamides as the key step.
1998, 9(8): 711-713
Abstract:
Five new Liquid Crystals with sulfonate units were synthesized. And they were determined by FT-IR and MS. The points of phase transition and the temperature ranges of liquid crystals were measured by means of DSC and PLM (Polarized Light Microscopy).
Five new Liquid Crystals with sulfonate units were synthesized. And they were determined by FT-IR and MS. The points of phase transition and the temperature ranges of liquid crystals were measured by means of DSC and PLM (Polarized Light Microscopy).
1998, 9(8): 715-716
Abstract:
7α-Hydroxycholesterol was prepared from cholesteryl acetate via allylic bromination followed by hydroxylation in 73% overall yield.
7α-Hydroxycholesterol was prepared from cholesteryl acetate via allylic bromination followed by hydroxylation in 73% overall yield.
1998, 9(8): 717-720
Abstract:
The reduction of 2,3-epoxy alcohol, prepared from the Sharpless asymmetric epoxidation, with the system of Ph3P, iodine, imidazole, 2,6-lutidine and water in Et20/CH3CN, gives a chiral secondary allylic alcohol in 94% yield and 92% e.e.. Using this reaction as the key step, we synthesized (-)-coniferyl alcohol derivative 1 starting from the geraniol through nine steps in an overall yield of 39%.
The reduction of 2,3-epoxy alcohol, prepared from the Sharpless asymmetric epoxidation, with the system of Ph3P, iodine, imidazole, 2,6-lutidine and water in Et20/CH3CN, gives a chiral secondary allylic alcohol in 94% yield and 92% e.e.. Using this reaction as the key step, we synthesized (-)-coniferyl alcohol derivative 1 starting from the geraniol through nine steps in an overall yield of 39%.
1998, 9(8): 721-722
Abstract:
A series of 2-benzoyliminopyrimido[3,2-b]-1,2,4-thiadiazolines were synthesized and tested for herbicidal effects. All of them are new compounds and their structures were confirmed by 1HNMR, IR, MS. The preliminary herbicidal tests show that some of the target compounds have potent activity and very good selectivity to rice.
A series of 2-benzoyliminopyrimido[3,2-b]-1,2,4-thiadiazolines were synthesized and tested for herbicidal effects. All of them are new compounds and their structures were confirmed by 1HNMR, IR, MS. The preliminary herbicidal tests show that some of the target compounds have potent activity and very good selectivity to rice.
1998, 9(8): 723-725
Abstract:
In view of the isosterism of sulfonyl group (-SO2-) and phosphoryl group [-P(0)(0R)-, R=H, CH3, C2H5, etc], a new type of ureas, that is, N-phosphoryl-N'-(4,6-dimethoxypyrimidin-2-yl) ureas 2 were synthesized and shown to be a new class of acetolactate synthase (ALS) inhibitors.
In view of the isosterism of sulfonyl group (-SO2-) and phosphoryl group [-P(0)(0R)-, R=H, CH3, C2H5, etc], a new type of ureas, that is, N-phosphoryl-N'-(4,6-dimethoxypyrimidin-2-yl) ureas 2 were synthesized and shown to be a new class of acetolactate synthase (ALS) inhibitors.
1998, 9(8): 727-729
Abstract:
Four functional cyclotriphosphazene liquid crystals have been synthesized. Their phase transition temperatures have also been measured by polarizing textural observation and confirming by DSC.
Four functional cyclotriphosphazene liquid crystals have been synthesized. Their phase transition temperatures have also been measured by polarizing textural observation and confirming by DSC.
Catalytic Hydrolysis of Lipophilic Amino Acid Esters by Metallomicelles as Carboxypeptidase A Models
1998, 9(8): 731-732
Abstract:
Lipophilic complexes of macrocyclic 12-membered dioxotetraamine ligand bearing bis-hydroxy groups as functional pendants are effective catalysts for the hydrolysis of amino acid es- ters in micellar media, and the rate enhancement of more than 10-fold were observed.
Lipophilic complexes of macrocyclic 12-membered dioxotetraamine ligand bearing bis-hydroxy groups as functional pendants are effective catalysts for the hydrolysis of amino acid es- ters in micellar media, and the rate enhancement of more than 10-fold were observed.
1998, 9(8): 733-734
Abstract:
A new 1 p-hydroxy-ent-kauren diterpenoid, enanderianin C 1, has been isolated from the leaves of Isodoti enanderianus, and its structure has been elucidated by spectroscopic evidences.
A new 1 p-hydroxy-ent-kauren diterpenoid, enanderianin C 1, has been isolated from the leaves of Isodoti enanderianus, and its structure has been elucidated by spectroscopic evidences.
1998, 9(8): 735-736
Abstract:
A novel tetrastilbene, davidol A, was isolated from the stems of Vitis davidii together with the previously known resveratrol, (+)-ε-viniferin; ampelopsin C; ampelopsin E; vitisin A and hopeaphenol. Its structure was elucidated mainly by ID and 2D NMR analyses.
A novel tetrastilbene, davidol A, was isolated from the stems of Vitis davidii together with the previously known resveratrol, (+)-ε-viniferin; ampelopsin C; ampelopsin E; vitisin A and hopeaphenol. Its structure was elucidated mainly by ID and 2D NMR analyses.
1998, 9(8): 737-738
Abstract:
A new ursane-type triterpene, 3β-hydroxy-urs-5(6)-en-28-oic acid 1, was isolated from the aerial parts of Teucrium integrifolium and characterized. The structure of this new compound was mainly established by 2D NMR techniques (COSY, HETCOR, HMBC).
A new ursane-type triterpene, 3β-hydroxy-urs-5(6)-en-28-oic acid 1, was isolated from the aerial parts of Teucrium integrifolium and characterized. The structure of this new compound was mainly established by 2D NMR techniques (COSY, HETCOR, HMBC).
1998, 9(8): 739-742
Abstract:
A new pregnane glycoside hypoglaucin G was isolated from Dioscorea collettii var. hypoglauca by bioactivity-guided fractionation, which showed a moderate activity of inducing morphological deformation of the Pyricularia oryzae mycelia. The structure of hypoglaucin G was established as 16β-(4'-methyl-5'-0-β-D-glucopyranosyl-pentanoyloxy)-pregn-5-en-3β-ol-20-one-3-0-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→4)-]-β-D-glucopyranoside by che- mical evidence and spectral analysis, especially by 2D-NMR techniques.
A new pregnane glycoside hypoglaucin G was isolated from Dioscorea collettii var. hypoglauca by bioactivity-guided fractionation, which showed a moderate activity of inducing morphological deformation of the Pyricularia oryzae mycelia. The structure of hypoglaucin G was established as 16β-(4'-methyl-5'-0-β-D-glucopyranosyl-pentanoyloxy)-pregn-5-en-3β-ol-20-one-3-0-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→4)-]-β-D-glucopyranoside by che- mical evidence and spectral analysis, especially by 2D-NMR techniques.
1998, 9(8): 743-745
Abstract:
A novel chemiluminescence (CL) sensor for NH4+ combined with flow injection analysis is presented in this paper. It is based on the inhibition effect of NH4+ on the CL reaction between luminol, immobilized electrostatically on an anion-exchange column, and hypochlorous acid electrogenerated on-line. The sensor responds linearly to NH4+ concentration in 1.0×lO-6-4.0×10-9 g/ml range. A complete analysis could be performed in 1 min. The system is stable for 200 determination
A novel chemiluminescence (CL) sensor for NH4+ combined with flow injection analysis is presented in this paper. It is based on the inhibition effect of NH4+ on the CL reaction between luminol, immobilized electrostatically on an anion-exchange column, and hypochlorous acid electrogenerated on-line. The sensor responds linearly to NH4+ concentration in 1.0×lO-6-4.0×10-9 g/ml range. A complete analysis could be performed in 1 min. The system is stable for 200 determination
1998, 9(8): 747-748
Abstract:
In this paper, the electrochemical behavior of bavistin (MBC) on glassy carbon electrode is reported. In a base solution of pH=9.0 NH3-NH4CI, a sensitive anodic peak was found by cyclic voltammetry. Differential pulse stripping voltammetry was applied for determining MBC in grains. The detection limit is 4×lO-8mol/L.The recovery is from 91.3% to 95.7%. The method has advantages of simplicity and high sensitivity.
In this paper, the electrochemical behavior of bavistin (MBC) on glassy carbon electrode is reported. In a base solution of pH=9.0 NH3-NH4CI, a sensitive anodic peak was found by cyclic voltammetry. Differential pulse stripping voltammetry was applied for determining MBC in grains. The detection limit is 4×lO-8mol/L.The recovery is from 91.3% to 95.7%. The method has advantages of simplicity and high sensitivity.
1998, 9(8): 749-751
Abstract:
A new kind of miniature conductance cell with thick electrodes was made, which has high resolution, high sensitivity, but no dead volume. A set of capillary electrophoresis device with on-column conductivity detector was assembled. In order to test the performance of this kind of mini-cell, different kinds of mini-cells were used to detect Li+, Na+, K+, Ca2+and Mg2+ ions.
A new kind of miniature conductance cell with thick electrodes was made, which has high resolution, high sensitivity, but no dead volume. A set of capillary electrophoresis device with on-column conductivity detector was assembled. In order to test the performance of this kind of mini-cell, different kinds of mini-cells were used to detect Li+, Na+, K+, Ca2+and Mg2+ ions.
1998, 9(8): 753-756
Abstract:
By applying the convolution technique to the treatment of oscillographic signal, a new electroanalytical method, 0.5-3.5 order differential A.C. oscillographic chronopotentiometry is presented. This note represents the experimental circuits, principle and characteristics of the method.
By applying the convolution technique to the treatment of oscillographic signal, a new electroanalytical method, 0.5-3.5 order differential A.C. oscillographic chronopotentiometry is presented. This note represents the experimental circuits, principle and characteristics of the method.
1998, 9(8): 757-760
Abstract:
A simple and convenient electrochemical detection cell for capillary electrophoresis is described in this paper. In this cell, alignment of the capillary working electrode with the separation capillary outlet can be achieved precisely and easily without the aid of the micropositioner or microscope. With end-column detection, the applicability of the cell as an amperometric detector for capillary electrophoresis is demonstrated by running several phenolic compounds in 50μim i.d. capillary with a capillary Pt electrode as the working electrode. Results obtained are satisfactory.
A simple and convenient electrochemical detection cell for capillary electrophoresis is described in this paper. In this cell, alignment of the capillary working electrode with the separation capillary outlet can be achieved precisely and easily without the aid of the micropositioner or microscope. With end-column detection, the applicability of the cell as an amperometric detector for capillary electrophoresis is demonstrated by running several phenolic compounds in 50μim i.d. capillary with a capillary Pt electrode as the working electrode. Results obtained are satisfactory.
1998, 9(8): 761-764
Abstract:
The laser-desorption-ionization time-of-flight mass spectrometry and desorption-electron-ionization mass spectrometry were employed for the characterization of metallofullerenes extract. It was found that the relative intensities of metallofullerenes in this positive-ion, negative-ion LD-TOF MS and DEI MS were much different. This phenomenon should have relationship with the peculiar ionization energies and electron affinities of metallofullerenes.
The laser-desorption-ionization time-of-flight mass spectrometry and desorption-electron-ionization mass spectrometry were employed for the characterization of metallofullerenes extract. It was found that the relative intensities of metallofullerenes in this positive-ion, negative-ion LD-TOF MS and DEI MS were much different. This phenomenon should have relationship with the peculiar ionization energies and electron affinities of metallofullerenes.
1998, 9(8): 765-766
Abstract:
13C and 99Ru-NMR chemical shifts are reported for the ruthenium(Ⅱ) tris complexes of 5-substituted 1,10-phenanthrolines. It has been found that both of them are affected by the substituents on the phenanthrolines in a direction consistent with that expected from the electron withdrawing ability of the substituent.
13C and 99Ru-NMR chemical shifts are reported for the ruthenium(Ⅱ) tris complexes of 5-substituted 1,10-phenanthrolines. It has been found that both of them are affected by the substituents on the phenanthrolines in a direction consistent with that expected from the electron withdrawing ability of the substituent.
1998, 9(8): 767-770
Abstract:
The states of small molecule H2 and N2 in the C60 cage have been studied. It is shown that the molecular stable configurations of the caged states exhibits little change compared with the free states, but the bond intensities of the caged states have become much stronger.
The states of small molecule H2 and N2 in the C60 cage have been studied. It is shown that the molecular stable configurations of the caged states exhibits little change compared with the free states, but the bond intensities of the caged states have become much stronger.
1998, 9(8): 771-774
Abstract:
The detailed dynamics of the CH4+CI→HC1+CH3 reaction has been investigated by means of the quasiclassical trajectory approach. The properties analyzed can be interpreted in terms of the main topological features of the potential energy surface used. On the basis of the theoretical results, two reaction channels are proposed: one is a direct channel and the other is a complex one.
The detailed dynamics of the CH4+CI→HC1+CH3 reaction has been investigated by means of the quasiclassical trajectory approach. The properties analyzed can be interpreted in terms of the main topological features of the potential energy surface used. On the basis of the theoretical results, two reaction channels are proposed: one is a direct channel and the other is a complex one.
1998, 9(8): 775-777
Abstract:
The partial oxidation of methane to syngas over Ni/ZrO2 catalyst irradiated by microwave has been studied. Compared with a conventional heating mode, the temperature of the catalytic bed is much lower and there is a higher selectivity of CO and H2 with microwave irradiation.
The partial oxidation of methane to syngas over Ni/ZrO2 catalyst irradiated by microwave has been studied. Compared with a conventional heating mode, the temperature of the catalytic bed is much lower and there is a higher selectivity of CO and H2 with microwave irradiation.
1998, 9(8): 779-782
Abstract:
Molecular dynamics simulations of model polyethylene chains with various lengths up to 4000 CH2 units were performed. Our results verified that the modification of force fields to demonstrate the collapse stages in the folding process is not necessary. The transition between the stages of chain folding became sharp, and the clusters became stable as the chain became longer.
Molecular dynamics simulations of model polyethylene chains with various lengths up to 4000 CH2 units were performed. Our results verified that the modification of force fields to demonstrate the collapse stages in the folding process is not necessary. The transition between the stages of chain folding became sharp, and the clusters became stable as the chain became longer.
1998, 9(8): 783-784
Abstract:
A new podand compound o-Bis(8'-quinolyloxy) ethylenoxyl benzene (BQEB) was prepared. A lanthanum adduct with BQEB was synthesized and its structure was characterized by X-ray crystal analysis. The La(Ⅲ) is ten-coordinated to the three N03+ and four H20. Two podand molecules are linked to the coordination core by four hydrogen bonds. The crystal is packed in the manner of.LLMLLMLL.
A new podand compound o-Bis(8'-quinolyloxy) ethylenoxyl benzene (BQEB) was prepared. A lanthanum adduct with BQEB was synthesized and its structure was characterized by X-ray crystal analysis. The La(Ⅲ) is ten-coordinated to the three N03+ and four H20. Two podand molecules are linked to the coordination core by four hydrogen bonds. The crystal is packed in the manner of.LLMLLMLL.
1998, 9(8): 785-787
Abstract:
Three new chiral binuclear organolanthanide alkoxides containing cyclopentadienyl ligand have been synthesised by the reaction of Cp3Ln (Cp=C5H5; Ln=Yb, Y, Dy) with 0.5 equimolar chiral diol in THF (tetrahydrofuran) at -78℃ at room temperature. All the complexes were characterized by elemental analysis, IR and MS spectra.
Three new chiral binuclear organolanthanide alkoxides containing cyclopentadienyl ligand have been synthesised by the reaction of Cp3Ln (Cp=C5H5; Ln=Yb, Y, Dy) with 0.5 equimolar chiral diol in THF (tetrahydrofuran) at -78℃ at room temperature. All the complexes were characterized by elemental analysis, IR and MS spectra.
1998, 9(8): 789-790
Abstract:
Dealuminated Y zeolite with high crystallinity is obtained from NaY zeolite by treatment with oxalic acid in a buffering system. The effect of dealumination conditions on the degree of dealumination and the crystallinity of the reformed zeolite is discussed. A mechanism for the reaction is proposed.
Dealuminated Y zeolite with high crystallinity is obtained from NaY zeolite by treatment with oxalic acid in a buffering system. The effect of dealumination conditions on the degree of dealumination and the crystallinity of the reformed zeolite is discussed. A mechanism for the reaction is proposed.
