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2001 Volume 12 Issue 3
2001, 12(3): 189-192
Abstract:
A novel enantioselective synthetic approach to 1,4-benzodioxane lignans was reported in which (2R, 3R)-and (2S, 3S)-2-(4-hydroxyphenyl)-3-hydroxymethyl-1, 4-benzodioxan-6-carbaldehyde were first synthesized.
A novel enantioselective synthetic approach to 1,4-benzodioxane lignans was reported in which (2R, 3R)-and (2S, 3S)-2-(4-hydroxyphenyl)-3-hydroxymethyl-1, 4-benzodioxan-6-carbaldehyde were first synthesized.
2001, 12(3): 193-194
Abstract:
2-substituted hexahydro-1H-1,4-diazepine analogues were synthesized starting from N,N-dibenzyl-1,3-propylene diamine and methyl-2,3-dibromo propionate through nucleophilic substitution, reduction, chlorination and debenzylation.
2-substituted hexahydro-1H-1,4-diazepine analogues were synthesized starting from N,N-dibenzyl-1,3-propylene diamine and methyl-2,3-dibromo propionate through nucleophilic substitution, reduction, chlorination and debenzylation.
2001, 12(3): 195-196
Abstract:
A benzyl oxazole compound 3 was obtained with an excellent yield of 90% when Nacetyl-(2'-methoxy-4',5'-methylenedioxy)-phenylalanine methyl ester 1 was refluxed in POCl3/benzene. However, the anticipated product 3,4-dihydroisoquinoline-3-carboxylic acid methyl ester 2 could not be found. The mechanism was discussed in this article.
A benzyl oxazole compound 3 was obtained with an excellent yield of 90% when Nacetyl-(2'-methoxy-4',5'-methylenedioxy)-phenylalanine methyl ester 1 was refluxed in POCl3/benzene. However, the anticipated product 3,4-dihydroisoquinoline-3-carboxylic acid methyl ester 2 could not be found. The mechanism was discussed in this article.
2001, 12(3): 197-198
Abstract:
12-Methoxypodocarpane-8,11,13-triene 1, the key intermediate in the synthesis of some important diterpenes, was synthesized in an efficient way, which has the characteristics of short route, simple operation and high yield.
12-Methoxypodocarpane-8,11,13-triene 1, the key intermediate in the synthesis of some important diterpenes, was synthesized in an efficient way, which has the characteristics of short route, simple operation and high yield.
2001, 12(3): 199-202
Abstract:
(±)epi-Chrysotricine 6 was synthesized by a cascade stereoselective oxidative cyclization of 5-hydroxyalkene 3 using tert-butyl hydroperoxide (TBHP) catalyzed by VO(acac)2.
(±)epi-Chrysotricine 6 was synthesized by a cascade stereoselective oxidative cyclization of 5-hydroxyalkene 3 using tert-butyl hydroperoxide (TBHP) catalyzed by VO(acac)2.
2001, 12(3): 203-204
Abstract:
10-vinyl-8,11,13-podocatriene 8, which is a model of Carnosic acid type diterpenes, has been synthesized by an expeditious convergent synthetic approach.
10-vinyl-8,11,13-podocatriene 8, which is a model of Carnosic acid type diterpenes, has been synthesized by an expeditious convergent synthetic approach.
2001, 12(3): 205-206
Abstract:
An enantioselective synthetic route to (+)-13-acetyl-12-hydroxy-podocarpane-8,11,13-triene-7-one 1a and (-)-13-acetyl-12-hydroxy-podocarpane-8,11,13-triene-7-one 1b was developed from (S)-(-)-α-cyclocitral 8a and (R)-(+)-α-cyclocitral 8b.
An enantioselective synthetic route to (+)-13-acetyl-12-hydroxy-podocarpane-8,11,13-triene-7-one 1a and (-)-13-acetyl-12-hydroxy-podocarpane-8,11,13-triene-7-one 1b was developed from (S)-(-)-α-cyclocitral 8a and (R)-(+)-α-cyclocitral 8b.
2001, 12(3): 207-210
Abstract:
A novel method of preparing dimethyl malonate by carbonylation of methyl chloroacetate catalyzed by Na[Co(CO)4] was proposed. Na[Co(CO)4] was synthesized in situ in the presence of Na2S2O3 and iron powder. The effects of some reaction parameters such as temperature, CO pressure and the concentrations of catalyst on the yields of dimethyl malonate were discussed. The kinetic data were studied and a possible reaction mechanism was proposed.
A novel method of preparing dimethyl malonate by carbonylation of methyl chloroacetate catalyzed by Na[Co(CO)4] was proposed. Na[Co(CO)4] was synthesized in situ in the presence of Na2S2O3 and iron powder. The effects of some reaction parameters such as temperature, CO pressure and the concentrations of catalyst on the yields of dimethyl malonate were discussed. The kinetic data were studied and a possible reaction mechanism was proposed.
2001, 12(3): 211-214
Abstract:
2,4,6-trichlorophenol (TCP) was firstly treated with air ions generated by electric discharge, and high dechlorination (53%) was observed after 60 min treatment, indicating that air ions are an efficient dechlorination means and might have a future in the oxidative removal of chlorinated phenols. In addition, a stepwise degradation of TCP, beginning with the formation of a major product 2,6-dichloro-1,4-benzenediol via substitution, is proposed through a detailed analysis of gas chromatography/mass spectrometry.
2,4,6-trichlorophenol (TCP) was firstly treated with air ions generated by electric discharge, and high dechlorination (53%) was observed after 60 min treatment, indicating that air ions are an efficient dechlorination means and might have a future in the oxidative removal of chlorinated phenols. In addition, a stepwise degradation of TCP, beginning with the formation of a major product 2,6-dichloro-1,4-benzenediol via substitution, is proposed through a detailed analysis of gas chromatography/mass spectrometry.
2001, 12(3): 215-218
Abstract:
Multiphoton ionization (MPI) of the hydrogen-bonded clusters C4H5N-(H2O)m was studied with a time of flight (TOF) mass spectrometer at 355 nm. Series of the pyrrole-watercluster ions were observed, including unprotonated cluster ions[C4H5N-(H2O)n]+, protonated cluster ions[C4H5N-(H2O)nH]+ and dehydrogenated cluster ions[C4H4N-(H2O)n]+. Both the experimental and ab initio calculated results agree with that the dehydrogenation has more probabilities to occur while the value of n is raised.
Multiphoton ionization (MPI) of the hydrogen-bonded clusters C4H5N-(H2O)m was studied with a time of flight (TOF) mass spectrometer at 355 nm. Series of the pyrrole-watercluster ions were observed, including unprotonated cluster ions[C4H5N-(H2O)n]+, protonated cluster ions[C4H5N-(H2O)nH]+ and dehydrogenated cluster ions[C4H4N-(H2O)n]+. Both the experimental and ab initio calculated results agree with that the dehydrogenation has more probabilities to occur while the value of n is raised.
2001, 12(3): 219-222
Abstract:
High-level density functional theory (DFT) calculations are performed for the first time to answer the question whether the arginine-carboxylate salt bridge stays in a zwitterionic state or a neutral one. The results indicate that in the gas phase, the neutral form is more stable and hence proton transfer occurs from guanidinium to carboxylate. However, in an aqueous solution the zwitterionic form should be favored. The difference might be caused by the electrostatic interaction between the salt bridge and its molecular environment. Therefore, the solvation effect has to be considered in the modeling of proteins, whose stabilization depends heavily on the saltbridges.
High-level density functional theory (DFT) calculations are performed for the first time to answer the question whether the arginine-carboxylate salt bridge stays in a zwitterionic state or a neutral one. The results indicate that in the gas phase, the neutral form is more stable and hence proton transfer occurs from guanidinium to carboxylate. However, in an aqueous solution the zwitterionic form should be favored. The difference might be caused by the electrostatic interaction between the salt bridge and its molecular environment. Therefore, the solvation effect has to be considered in the modeling of proteins, whose stabilization depends heavily on the saltbridges.
2001, 12(3): 223-226
Abstract:
Stochastic resonance (SR) is shown in a two-parameter system, a model of electrodissolution of Fe in H2SO4. Modulation of two different parameters by a periodic signal in one parameter and noise in the other parameter is found to give rise to SR. The result indicates that the noise can enlarge a weak periodic signal and lead the system to order. The scenario and novel aspects of SR in this system are discussed.
Stochastic resonance (SR) is shown in a two-parameter system, a model of electrodissolution of Fe in H2SO4. Modulation of two different parameters by a periodic signal in one parameter and noise in the other parameter is found to give rise to SR. The result indicates that the noise can enlarge a weak periodic signal and lead the system to order. The scenario and novel aspects of SR in this system are discussed.
2001, 12(3): 227-230
Abstract:
7α-Hydroxy-8β,9β-H-cis-bicyclo[4,3,0]non-4-ene-4-aldehyde, a nonane compound with novel skeleton, named tsaokoin, was isolated from the fruits of Amomum tsao-ko. Its structure was established on the basis of spectral analysis.
7α-Hydroxy-8β,9β-H-cis-bicyclo[4,3,0]non-4-ene-4-aldehyde, a nonane compound with novel skeleton, named tsaokoin, was isolated from the fruits of Amomum tsao-ko. Its structure was established on the basis of spectral analysis.
2001, 12(3): 231-232
Abstract:
A new flavone glycoside, 5,8-dihydroxy-4',6,7-trimethoxyflavone 8-O-β-Dglucopyranoside 1, together with three known flavonoids, pedalitin 2, cirsimartin 3 and genkwanin 4, were isolated from the aerial parts of Isodon enanderianus. Their structures were determined on the basis of spectral data.
A new flavone glycoside, 5,8-dihydroxy-4',6,7-trimethoxyflavone 8-O-β-Dglucopyranoside 1, together with three known flavonoids, pedalitin 2, cirsimartin 3 and genkwanin 4, were isolated from the aerial parts of Isodon enanderianus. Their structures were determined on the basis of spectral data.
2001, 12(3): 233-234
Abstract:
A new flavanone named macrouroine C (1) was isolated from the bark of Morus macroura Miq.. The structure of 1 was elucidated mainly on the basis of spectroscopic evidence.
A new flavanone named macrouroine C (1) was isolated from the bark of Morus macroura Miq.. The structure of 1 was elucidated mainly on the basis of spectroscopic evidence.
2001, 12(3): 235-238
Abstract:
From the marine sponge Xestospongia exigua, fungal isolates of Aspergillus versicolor (Vuill) Triab were obtained. Isolation and purification of ethyl acetate extracts from culture filtrates of the fungus led to yield six new chromone derivatives namely aspergione A, aspergione B, aspergione C, aspergione D, aspergione E, aspergione F. The structures of all the new compounds were established on the bas is of extensive spectroscopy (UV, MS, 1H and 13C NMR, COSY, HMQC and HMBC) analysis.
From the marine sponge Xestospongia exigua, fungal isolates of Aspergillus versicolor (Vuill) Triab were obtained. Isolation and purification of ethyl acetate extracts from culture filtrates of the fungus led to yield six new chromone derivatives namely aspergione A, aspergione B, aspergione C, aspergione D, aspergione E, aspergione F. The structures of all the new compounds were established on the bas is of extensive spectroscopy (UV, MS, 1H and 13C NMR, COSY, HMQC and HMBC) analysis.
2001, 12(3): 239-242
Abstract:
Two new dammarane glycosides named notoginsenoside T1 and T2 were isolated from the mild acid hydrolysis products of the root saponins of Panax notoginseng. On the basis of spectroscopic evidences, their structures were elucidated to be 6-O-β-D-glucopyranosyl-24(25)-epoxy-3β,6α,12β,23 ζ-tetrahydroxydammar-20(22)(E)-ene 1 and 6-O-β-D-glucopyranosyl-24(25)-epoxy-23 ζ-methoxyl-3β,6α,12β-trihydroxydamm-ar-20(22)(E)-ene 2, respectively.
Two new dammarane glycosides named notoginsenoside T1 and T2 were isolated from the mild acid hydrolysis products of the root saponins of Panax notoginseng. On the basis of spectroscopic evidences, their structures were elucidated to be 6-O-β-D-glucopyranosyl-24(25)-epoxy-3β,6α,12β,23 ζ-tetrahydroxydammar-20(22)(E)-ene 1 and 6-O-β-D-glucopyranosyl-24(25)-epoxy-23 ζ-methoxyl-3β,6α,12β-trihydroxydamm-ar-20(22)(E)-ene 2, respectively.
2001, 12(3): 243-244
Abstract:
A new indole alkaloid, crenulatine 1, was isolated from the stems of Limonia Crenulata. The structure was identified by spectral means.
A new indole alkaloid, crenulatine 1, was isolated from the stems of Limonia Crenulata. The structure was identified by spectral means.
2001, 12(3): 245-246
Abstract:
A novel ursane triterpene, named swinhoeic acid, was isolated from the roots of Rubus swinhoei. Its structure was elucidated as 18, 19-seco, 2α, 3β-dihydroxy-19-oxo-urs-11, 13(18)-dien-28-oic acid by means of MS, 1DNMR and 2DNMR.
A novel ursane triterpene, named swinhoeic acid, was isolated from the roots of Rubus swinhoei. Its structure was elucidated as 18, 19-seco, 2α, 3β-dihydroxy-19-oxo-urs-11, 13(18)-dien-28-oic acid by means of MS, 1DNMR and 2DNMR.
2001, 12(3): 247-248
Abstract:
A novel norditerpene, miliusate (1), was isolated from Miliusa balansae Finet et Gagnep. Its structure was elucidated by spectral analysis.
A novel norditerpene, miliusate (1), was isolated from Miliusa balansae Finet et Gagnep. Its structure was elucidated by spectral analysis.
2001, 12(3): 249-252
Abstract:
A novel Ni-Co/SiO2 catalyst which exhibits high activity and excellent anti-carbon deposition property for CO2 reforming of CH4 to synthesis gas is developed.
A novel Ni-Co/SiO2 catalyst which exhibits high activity and excellent anti-carbon deposition property for CO2 reforming of CH4 to synthesis gas is developed.
2001, 12(3): 253-256
Abstract:
A new method for preparing LiLaNiO/γ-Al2O3 monolithic catalyst was described and discussed. The catalyst, which was supported over the monolith, was evaluated in a POM to syngas process. Relative stable catalytic properties during the 120 hours operation at atmospheric pressure were found for the catalyst. Under the high space velocity of 9.0×104l/(kg·h)(CH4), the conversion of methane came to 95.5%, and the selectivity of carbon monoxide was not below 96.0% at 1123K when ratio of the feedstock (CH4/O2) was equal to 2.0.
A new method for preparing LiLaNiO/γ-Al2O3 monolithic catalyst was described and discussed. The catalyst, which was supported over the monolith, was evaluated in a POM to syngas process. Relative stable catalytic properties during the 120 hours operation at atmospheric pressure were found for the catalyst. Under the high space velocity of 9.0×104l/(kg·h)(CH4), the conversion of methane came to 95.5%, and the selectivity of carbon monoxide was not below 96.0% at 1123K when ratio of the feedstock (CH4/O2) was equal to 2.0.
2001, 12(3): 257-260
Abstract:
A new polymer-supported metallocene catalyst has been prepared. The polymersupported metallocene displayed considerably high activity in ethylene polymerization,the highest being 3.62×107gPE/molZr·h, the molecular weight of the polyethylene produced was Mn=1.29×105, about 3-4 times those of corresponding homogeneous zirconocenes. The polymersupported metallocene keeps the characteristics of homogeneous metallocene catalysts, and offers some features,such as adaptable to gas phase and slurry processes; easy to prepare in low cost; relatively high activity and lower MAO/Zr ratio; lower inorganic residues in the polyolefins as compared to cases of SiO2,Al2O3 or MgCl2; unitary active structure, no complex surface as with SiO2; good control of morphology of the resulting polymer.
A new polymer-supported metallocene catalyst has been prepared. The polymersupported metallocene displayed considerably high activity in ethylene polymerization,the highest being 3.62×107gPE/molZr·h, the molecular weight of the polyethylene produced was Mn=1.29×105, about 3-4 times those of corresponding homogeneous zirconocenes. The polymersupported metallocene keeps the characteristics of homogeneous metallocene catalysts, and offers some features,such as adaptable to gas phase and slurry processes; easy to prepare in low cost; relatively high activity and lower MAO/Zr ratio; lower inorganic residues in the polyolefins as compared to cases of SiO2,Al2O3 or MgCl2; unitary active structure, no complex surface as with SiO2; good control of morphology of the resulting polymer.
2001, 12(3): 261-264
Abstract:
Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (Koc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the related breakthrough curves (BTC). The nine pesticides chosen for determination in this study are soluble ones, with their water solubility ranging from 62 mg/L to 2 mg/L. In comparing with existing methods of Koc, SCLC possesses rapid, online and accurate characteristics.
Soil column liquid chromatography (SCLC) was developed to determine soil organic carbon adsorption coefficients (Koc) for chemicals. The uptake by soil of pesticides from water can be conveniently calculated from the related breakthrough curves (BTC). The nine pesticides chosen for determination in this study are soluble ones, with their water solubility ranging from 62 mg/L to 2 mg/L. In comparing with existing methods of Koc, SCLC possesses rapid, online and accurate characteristics.
2001, 12(3): 265-266
Abstract:
An on-line multichannel Raman spectroscopic detection system for capillary electrophoresis was established by using an Ar+ laser and a cryogenically cooled ICCD. Resonant excitation Raman spectra of methyl red and methyl orange were employed to test the system. The result shows that it could yield on-line electrophoretogram and time series of Raman spectra.
An on-line multichannel Raman spectroscopic detection system for capillary electrophoresis was established by using an Ar+ laser and a cryogenically cooled ICCD. Resonant excitation Raman spectra of methyl red and methyl orange were employed to test the system. The result shows that it could yield on-line electrophoretogram and time series of Raman spectra.
2001, 12(3): 267-268
Abstract:
A new chemiluminescent reagent 7-(4,6-dichloro-1,3,5-triazinylamino)-4-methylcoumarin (DTMC) was synthesized by linking 7-amino-4-methylcoumarin to cyanuric chloride at 0-5℃, and with it a novel chemiluminescence method was developed for the determination of hydrogen peroxide. The selectivity of this method is high, and most of the transition metal ions have no effect on the determination of H2O2.
A new chemiluminescent reagent 7-(4,6-dichloro-1,3,5-triazinylamino)-4-methylcoumarin (DTMC) was synthesized by linking 7-amino-4-methylcoumarin to cyanuric chloride at 0-5℃, and with it a novel chemiluminescence method was developed for the determination of hydrogen peroxide. The selectivity of this method is high, and most of the transition metal ions have no effect on the determination of H2O2.
2001, 12(3): 269-270
Abstract:
Polyionic complex DHP-PDDA was prepared by reacting anionic surfactant dihexadecyl phosphate (DHP) with polycationic poly(diallyldimethyl ammonium) (PDDA). Thin films made from DHP-PDDA with incorporated hemoglobin (Hb) on pyrolytic graphite (PG) electrodes were characterized by electrochemistry and other techniques.
Polyionic complex DHP-PDDA was prepared by reacting anionic surfactant dihexadecyl phosphate (DHP) with polycationic poly(diallyldimethyl ammonium) (PDDA). Thin films made from DHP-PDDA with incorporated hemoglobin (Hb) on pyrolytic graphite (PG) electrodes were characterized by electrochemistry and other techniques.
2001, 12(3): 271-272
Abstract:
The surface pressure-area (π-A) isotherm of Schiff base aluminium (III), tris (2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium (III) (denoted as Al(TA12)3), on pure water subphase was investigated. The molecular area, 0.48 nm2, is one-third of expected value that indicated the aggregation took place. The Langmuir-Blodgett (LB) films of Al(TA12)3 was transferred and characterized. The AFM image confirmed the formation of aggregates.
The surface pressure-area (π-A) isotherm of Schiff base aluminium (III), tris (2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium (III) (denoted as Al(TA12)3), on pure water subphase was investigated. The molecular area, 0.48 nm2, is one-third of expected value that indicated the aggregation took place. The Langmuir-Blodgett (LB) films of Al(TA12)3 was transferred and characterized. The AFM image confirmed the formation of aggregates.
2001, 12(3): 273-274
Abstract:
The rheometrics ARES rheometer was applied to determining the rheological behavior of a thermotropic liquid crystalline poly (aryl ether ketone). The viscosity of the material decreases with increasing temperature, reaching a minimum in the nematic state, then slightly increases with further raising the temperature in the biphase.
The rheometrics ARES rheometer was applied to determining the rheological behavior of a thermotropic liquid crystalline poly (aryl ether ketone). The viscosity of the material decreases with increasing temperature, reaching a minimum in the nematic state, then slightly increases with further raising the temperature in the biphase.
2001, 12(3): 275-278
Abstract:
In the synthesis of HMS, Soxhlet extraction as a new method to remove neutral template was studied. HREM image, X-ray diffraction patterns and nitrogen adsorption-desorption results verified that this method can not only efficiently remove and recoverthe template, but also benefit the maintenance of the mesoporous framework structure.
In the synthesis of HMS, Soxhlet extraction as a new method to remove neutral template was studied. HREM image, X-ray diffraction patterns and nitrogen adsorption-desorption results verified that this method can not only efficiently remove and recoverthe template, but also benefit the maintenance of the mesoporous framework structure.
2001, 12(3): 279-282
Abstract:
A new nonlinear optical complex crystal tetrakis (thiourea) mercury (II) tetrakis (thiocyanato-N) zinc (II) was synthesized and its structure was determined. It belongs to the tetragonal system, I4 space group. The crystal structure consists of discrete[Zn(SCN)4]2- anions and[Hg(NH2CSNH2)4]2+ cations with slightly distorted coordination tetrahedra ZnN4 and HgS4. The second harmonic generation (SHG) of the crystal was found to be superior to that of urea.
A new nonlinear optical complex crystal tetrakis (thiourea) mercury (II) tetrakis (thiocyanato-N) zinc (II) was synthesized and its structure was determined. It belongs to the tetragonal system, I4 space group. The crystal structure consists of discrete[Zn(SCN)4]2- anions and[Hg(NH2CSNH2)4]2+ cations with slightly distorted coordination tetrahedra ZnN4 and HgS4. The second harmonic generation (SHG) of the crystal was found to be superior to that of urea.
