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1999 Volume 10 Issue 4
1999, 10(4): 269-270
Abstract:
A new condensation reaction of β-Keto-δ-valerolactones was developed. The condensation products are composed of a pair of isomers because of the formation of intramolecular hydrogen bond. Their structures were confirmed by 1HNMR and elemental analysis.
A new condensation reaction of β-Keto-δ-valerolactones was developed. The condensation products are composed of a pair of isomers because of the formation of intramolecular hydrogen bond. Their structures were confirmed by 1HNMR and elemental analysis.
1999, 10(4): 271-272
Abstract:
The reactions of halocarbenes with pre-aromatic ketones 1, 2 resulted in cyclopropanation and deoxygenation products. The varying product ratio could be accounted for by a mechanism involving the carbonyl ylide intermediate.
The reactions of halocarbenes with pre-aromatic ketones 1, 2 resulted in cyclopropanation and deoxygenation products. The varying product ratio could be accounted for by a mechanism involving the carbonyl ylide intermediate.
1999, 10(4): 273-274
Abstract:
β-Cyclodextrin(β-CD) was directly oxidized in high yield to the corresponding monoaldehyde by cyclized 2-iodoxybenzoic acid (IBX) in DMSO.
β-Cyclodextrin(β-CD) was directly oxidized in high yield to the corresponding monoaldehyde by cyclized 2-iodoxybenzoic acid (IBX) in DMSO.
1999, 10(4): 275-276
Abstract:
Starting from podophyllotoxin, five new derivatives with macrocyclic dilactone 5~9 have been synthesized,and their structures were confirmed by IR, MS, 1H NMR as well as HRMS. The key step is cyclization by high dilution method.
Starting from podophyllotoxin, five new derivatives with macrocyclic dilactone 5~9 have been synthesized,and their structures were confirmed by IR, MS, 1H NMR as well as HRMS. The key step is cyclization by high dilution method.
1999, 10(4): 277-280
Abstract:
In this paper, 2-(l, 3, 4-triazolylazo)-5-diethylamino phenol (TZAPN) and 2-(5-carboxy-1. 3, 4-triazolylazo)-5-diethylamino phenol (CTZAPN) were prepared, the protonation behaviour and the condition of spectrophotometric determination of cobalt with the reagents are reported. The results show that the new colour reagents react with cobalt to form a stable purple red complex (1:3). However, the complex formed could be changed into another species of stable absorptivity by addition of mineral acid (1+1). The method is highly selective and sensitive and has been applied to the direct determination of cobalt in some alloys with satisfactory results.
In this paper, 2-(l, 3, 4-triazolylazo)-5-diethylamino phenol (TZAPN) and 2-(5-carboxy-1. 3, 4-triazolylazo)-5-diethylamino phenol (CTZAPN) were prepared, the protonation behaviour and the condition of spectrophotometric determination of cobalt with the reagents are reported. The results show that the new colour reagents react with cobalt to form a stable purple red complex (1:3). However, the complex formed could be changed into another species of stable absorptivity by addition of mineral acid (1+1). The method is highly selective and sensitive and has been applied to the direct determination of cobalt in some alloys with satisfactory results.
1999, 10(4): 281-284
Abstract:
The lactone 16 was obtained stereo-and regioselectively by a reaction sequence of 9 steps in 21 0ro overall yield.
The lactone 16 was obtained stereo-and regioselectively by a reaction sequence of 9 steps in 21 0ro overall yield.
1999, 10(4): 285-288
Abstract:
Eight tri(2-methyl-2-phenylpropyl) germylpropionates have been synthesized. and their structures were characterized by elemental analysis, IR, multinuclear NMR (1H.13C.119Sn) and MS. The spectroscopic studies revealed that compounds of this type possess a tetrahedral geometry, which have been expected to have good biological activity.
Eight tri(2-methyl-2-phenylpropyl) germylpropionates have been synthesized. and their structures were characterized by elemental analysis, IR, multinuclear NMR (1H.13C.119Sn) and MS. The spectroscopic studies revealed that compounds of this type possess a tetrahedral geometry, which have been expected to have good biological activity.
1999, 10(4): 289-290
Abstract:
A new Euphane-type triterpene, named azedarachic acid, was isolated from the fruits of Melia azedarach. Its structure was determined on the basis of NMR and MS experiments.
A new Euphane-type triterpene, named azedarachic acid, was isolated from the fruits of Melia azedarach. Its structure was determined on the basis of NMR and MS experiments.
1999, 10(4): 291-294
Abstract:
A pair of novel geometrically isomeric triterpenoid saponins named escins IVa and IVb, together with known escins to and Ib, were isolated from the seeds of Aesculus chinensis. Their structures were determined on the basis of spectroscopic evidences and comparison.
A pair of novel geometrically isomeric triterpenoid saponins named escins IVa and IVb, together with known escins to and Ib, were isolated from the seeds of Aesculus chinensis. Their structures were determined on the basis of spectroscopic evidences and comparison.
1999, 10(4): 295-296
Abstract:
A new flavonoid glycoside, 5, 7-dihydroxy-4'-methoxyflavonoid 7-O-[6-O-(4-O-acetyl-α-L-rhamnosyl)-3-O-β-D-glucosyl]-6-O-acetyl-β-D-glucoside was isolated from Thalictrum prewalskii. Its structure was determined on basis of spectroscopic evidences.
A new flavonoid glycoside, 5, 7-dihydroxy-4'-methoxyflavonoid 7-O-[6-O-(4-O-acetyl-α-L-rhamnosyl)-3-O-β-D-glucosyl]-6-O-acetyl-β-D-glucoside was isolated from Thalictrum prewalskii. Its structure was determined on basis of spectroscopic evidences.
1999, 10(4): 297-298
Abstract:
A new compound, lepida acid A 1, has been isolated from the fruiting bodies of Basidiomycetes Russula lepida. Its structure was elucidated by spectral methods.
A new compound, lepida acid A 1, has been isolated from the fruiting bodies of Basidiomycetes Russula lepida. Its structure was elucidated by spectral methods.
1999, 10(4): 299-302
Abstract:
A novel cyclopeptide, squamin-A has been isolated from the seeds of Annona squamosa Linn.. The structure was elucidated by extensive 2D-NMR, FABMS and amino acid analysis in combination with Marfey's reagents as cyclo-[l-prolyl-l-(S-oxo)-methionyl-l-tyrosyl-l-glycyl-l-threonyl-l-valyl-l-alanyl-l-isoleucyl].
A novel cyclopeptide, squamin-A has been isolated from the seeds of Annona squamosa Linn.. The structure was elucidated by extensive 2D-NMR, FABMS and amino acid analysis in combination with Marfey's reagents as cyclo-[l-prolyl-l-(S-oxo)-methionyl-l-tyrosyl-l-glycyl-l-threonyl-l-valyl-l-alanyl-l-isoleucyl].
1999, 10(4): 303-306
Abstract:
A successful chiral separation of N-benzoyl phenylalanine methyl ester has been achieved by nonaqueous capillary electrophoresis (NACE) using β-CD as chiral selector in formamide (FA). Some experimental parameters influencing the chiral separation such as concentration of β-CD, ionic strength and apparent pH (pH*) are discussed.
A successful chiral separation of N-benzoyl phenylalanine methyl ester has been achieved by nonaqueous capillary electrophoresis (NACE) using β-CD as chiral selector in formamide (FA). Some experimental parameters influencing the chiral separation such as concentration of β-CD, ionic strength and apparent pH (pH*) are discussed.
1999, 10(4): 307-310
Abstract:
The chemically modified electrode (CME) which was constructed by covalent attaching erythromycin (ERM) to the glassy carbon (GC) surface was investigated in Tris-HCI buffer (pH=6.0) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the potential range of -0.5~0.4V, CME yields a pair of stable redox wave. It is the carbonyl group of the ERM molecule immobilized on the GC surface that undergoes two electron redox process involving two protons. The interaction of CME with DNA was also studied by DPV. The CME shows the same interaction with DNA as that in the solution. And the result was proved by fluorescence.
The chemically modified electrode (CME) which was constructed by covalent attaching erythromycin (ERM) to the glassy carbon (GC) surface was investigated in Tris-HCI buffer (pH=6.0) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the potential range of -0.5~0.4V, CME yields a pair of stable redox wave. It is the carbonyl group of the ERM molecule immobilized on the GC surface that undergoes two electron redox process involving two protons. The interaction of CME with DNA was also studied by DPV. The CME shows the same interaction with DNA as that in the solution. And the result was proved by fluorescence.
1999, 10(4): 311-312
Abstract:
A novel method based on microbe modification has been employed to prepare gold thin film electrode. The preparation method is simple and the electrode obtained is stable and very sensitive in determining heavy metal ions. The quantitation limit of Cu2+ is 0.05 ng/mL.
A novel method based on microbe modification has been employed to prepare gold thin film electrode. The preparation method is simple and the electrode obtained is stable and very sensitive in determining heavy metal ions. The quantitation limit of Cu2+ is 0.05 ng/mL.
1999, 10(4): 312-324
Abstract:
The mass spectra of cluster ions (NH3)nH2+ with n<4 were measured for the first time using a MPI mass spectrometer. The structures of the cluster ions NH5+ and (NH3)2H2+ were calculated using GAUSSIAN-94 package, and stable structures for both of them were found.
The mass spectra of cluster ions (NH3)nH2+ with n<4 were measured for the first time using a MPI mass spectrometer. The structures of the cluster ions NH5+ and (NH3)2H2+ were calculated using GAUSSIAN-94 package, and stable structures for both of them were found.
1999, 10(4): 313-316
Abstract:
The inclusion complex of podophyllotoxin (P) with β-cyclodextrin(β-CD) has been studied by X-ray diffractometry and 1HNMR, 13CNMR spectroscopy. The complex structure is deduced.
The inclusion complex of podophyllotoxin (P) with β-cyclodextrin(β-CD) has been studied by X-ray diffractometry and 1HNMR, 13CNMR spectroscopy. The complex structure is deduced.
1999, 10(4): 317-327
Abstract:
Semi-empirical molecular orbital theory AMI method is employed to study the orthoposition substituent impact on intramolecular proton transfer reaction of perylenequinone. The calculation demonstrates that the perylenequinone molecule is of stable structure, and all substituents may cause the decrease of barriers for the hydrogen transfer reaction.
Semi-empirical molecular orbital theory AMI method is employed to study the orthoposition substituent impact on intramolecular proton transfer reaction of perylenequinone. The calculation demonstrates that the perylenequinone molecule is of stable structure, and all substituents may cause the decrease of barriers for the hydrogen transfer reaction.
1999, 10(4): 325-326
Abstract:
The selected-state probabilities of collinear ion-pair formation process Na+I2→Na++I2- on Aten-Laming-Los two-state potential energy surface have been calculated by using LCAC-SW method. The results show that reaction probabilities are oscillatory with collision energy; the threshold energy of this ionization reaction is 2.8 ev, which is in modest agreement with experimental result.
The selected-state probabilities of collinear ion-pair formation process Na+I2→Na++I2- on Aten-Laming-Los two-state potential energy surface have been calculated by using LCAC-SW method. The results show that reaction probabilities are oscillatory with collision energy; the threshold energy of this ionization reaction is 2.8 ev, which is in modest agreement with experimental result.
1999, 10(4): 327-330
Abstract:
The biodegradation behavior in vitro and in vivo of polycaprolactone-poly (ethylene glycol) block copolymer (PCE) was reported in detail. In this paper, photodegradation test of PCE was performed by exposure to UV light. The mechanical properties and the inherent viscosity of PCE samples which are subjected to photodegradation were determined. The experimental results indicated that poly (ethylene glycol) (PEO) segment in PCE copolymer is photosensitive. The photodegra-dation rate of the PCE was increased with increasing poly (ethylene glycol) content.
The biodegradation behavior in vitro and in vivo of polycaprolactone-poly (ethylene glycol) block copolymer (PCE) was reported in detail. In this paper, photodegradation test of PCE was performed by exposure to UV light. The mechanical properties and the inherent viscosity of PCE samples which are subjected to photodegradation were determined. The experimental results indicated that poly (ethylene glycol) (PEO) segment in PCE copolymer is photosensitive. The photodegra-dation rate of the PCE was increased with increasing poly (ethylene glycol) content.
1999, 10(4): 331-332
Abstract:
Effect of dissolved CO2 on bovine serum albumin (BSA) solubilization in the reverse micelles of sodium bis (2-ethylhexyl) sulfosuccinate (AOT) in 2,2,4-trimethylpentane (iso-octane) has been studied at 308.2 K. It was found that BSA can be precipitated completely by CO2 while the AOT and water remain in the iso-octane continuous phase. This opens up a possibility for recovery of pure protein solids directly from reverse micellar solutions.
Effect of dissolved CO2 on bovine serum albumin (BSA) solubilization in the reverse micelles of sodium bis (2-ethylhexyl) sulfosuccinate (AOT) in 2,2,4-trimethylpentane (iso-octane) has been studied at 308.2 K. It was found that BSA can be precipitated completely by CO2 while the AOT and water remain in the iso-octane continuous phase. This opens up a possibility for recovery of pure protein solids directly from reverse micellar solutions.
1999, 10(4): 333-334
Abstract:
The thermostability and the interference-resisting property of germanium (Ge) in graphite furnace atomic absorption spectrometry (GF.AAS) were increased remarkably when palladium and lithium nitrates were used as complexing matrix modifiers and barium nitrate as supplementary matrix modifier.
The thermostability and the interference-resisting property of germanium (Ge) in graphite furnace atomic absorption spectrometry (GF.AAS) were increased remarkably when palladium and lithium nitrates were used as complexing matrix modifiers and barium nitrate as supplementary matrix modifier.
1999, 10(4): 335-338
Abstract:
From a basic solution containing cetyltrimethylammonium cations as the template. thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel axis of the film is oriented parallel with the surface plane of the substrate, and the film is stable after careful removal of template in vacuum.
From a basic solution containing cetyltrimethylammonium cations as the template. thin film of mesoporous MCM-41 has been grown on the surface of a pre-treated indium-tin-oxide conducting glass substrate. The channel axis of the film is oriented parallel with the surface plane of the substrate, and the film is stable after careful removal of template in vacuum.
1999, 10(4): 339-340
Abstract:
Anode material for lithium ion battery is prepared by chemical oxidation of natural graphite. After oxidation, the properties of natural graphite are modified, such as surface structure, the content of graphite phases, the number of micropores and its stability, thus the modified natural graphite can be used as anode material for commercial lithium ion battery. The reversible capacity is increased from 100 mAh/g to above 300 mAh/g, and its cycling property is also satisfactory.
Anode material for lithium ion battery is prepared by chemical oxidation of natural graphite. After oxidation, the properties of natural graphite are modified, such as surface structure, the content of graphite phases, the number of micropores and its stability, thus the modified natural graphite can be used as anode material for commercial lithium ion battery. The reversible capacity is increased from 100 mAh/g to above 300 mAh/g, and its cycling property is also satisfactory.
