Showing papers in "Journal of The Chinese Chemical Society in 1992"
TL;DR: Oxygenated lanostanoid triterpenes from Chinese medicinal fungus Ganoderma lucidum (Fr.) Karst were identified in this article, including multiple pairs of C-3 stereoisomers and C- 3/C-15 positional isomers.
Abstract: Oxygenated lanostanoid triterpenes including multiple pairs of C-3 stereoisomers and C-3/C-15 positional isomers were identified from the Chinese medicinal fungus Ganoderma lucidum (Fr.) Karst. Empirical rules based on the chromatographic behavior in reversed-phase HPLC were developed to correlate the molecular polarities due to the presence of an individual functional group. 13C NMR correlation of stereochemistry in these oxygenated triterpenes was also achieved. Biosynthetic studies indicated that oxygenated triterpenes in the 3α series were derived from those in the 3β series through an oxidationreduction pathway. Several oxygenated triterpenes inhibited cholesterol synthesis in the in vitro assay. Ganodermic acid S induced platelet aggregation by stimulating the hydrolysis of phosphatidylinositol 4,5-bisphosphate.
43 citations
TL;DR: Artificial macrocyclic polyethers were synthesized and applied as ionselective electrode neutral carriers in PVC electrode membranes, ion-chromatographic packing materials, extractants and adsorbents for ion separations, phase-transfer catalysts for organic reactions, surfactants, liquid crystals and ion-transport carriers through liquid membranes as mentioned in this paper.
Abstract: Artificial macrocyclic polyethers were synthesized and applied as ion-selective electrode neutral carriers in PVC electrode membranes, ion-chromatographic packing materials, extractants and adsorbents for ion separations, phase-transfer catalysts for organic reactions, surfactants, liquid crystals and ion-transport carriers through liquid membranes. Ion selective electrodes such as K+, Na+, UO22+, Cs+, Pb2+ and Fe3+, Hg2+ and Ag+ ion electrodes based on crown ether - phosphotungstic acid (PW) precipitates and dithio crown ethers respectively were prepared and showed good sensitivity and selectivity. Crown ether - PW precipitates were also applied as adsorbents for adsorptions of rare-earth ions and some common heavy metal ions. Some rare-earth ions were found to be easily extracted with crown ethers especially 15-crown-5. Poly(styrene/divinyl benzene)-cryptand 22 resin was synthesized and applied as a bifunctional stationary phase of ion chromatography for separations of both cations and anions even some organic carboxylate geometric isomers A so called “drift-type” crown ether catalyst and some common crown ether catalysts were applied to catalyze organic oxidation, reduction, substitution and anionic polymerization. The effect of salts on micellar formation and stability, of liquid crystals of some crown-ether surfactants were investigated. Some special crown-ether carriers were also prepared and applied for Na+, K+ and Mg2+ ion transport through liquid membranes.
39 citations
TL;DR: In this paper, the anilinium ion was encapsulated into the interlayer space of montmorillonite and the intrachannel space of NaY zeolite by the ion exchange method.
Abstract: The anilinium ion was encapsulated into the interlayer space of montmorillonite and the intrachannel space of NaY zeolite by the ion exchange method. After addition of ammonium peroxodisulfate, the loaded anilinium ions were polymerized to polyaniline (PAN). The structures of PAN in NaM and CsM are compared with that in NaY by means of UV-Vis, FTIR and EPR spectroscopies. The structures of PAN in NaY zeolite and montmorillonite hosts were shown to have the typical spectral features of emeraldine base and emeraldine salt respectively. Intercalation of polyaniline in montmorillonite was confirmed by the variation of the basal spacing, the resonances in EPR and the reduction of bulk conductivity.
34 citations
TL;DR: By combination of centrifugal partition chromatography (CPC) and common separation methods, twelve known bases were isolated and characterized from the first chemical investigation of Neolitsea konishii (H.) K. & S. K. as mentioned in this paper.
Abstract: By combination of centrifugal partition chromatography (CPC) and common separation methods, twelve known bases were isolated and characterized from the first chemical investigation of Neolitsea konishii (H.) K. & S. They belong to isoquinoline alkaloids of four types: eight aporphines, nornuciferine (1), N-methyllaurotetanine (2), laurolitsine (3), boldine (4), laurotetanine (5), isoboldine (6), actinodaphine (7) and corytuberine (8); two proaporphines, stepharine (9) and glaziovine (10); one benzylisoquinoline, reticuline (11); and one morphinan, pallidine (12). Among these, compounds 3, 6 and 11 are abundant and will be modified for pharmacological tests. The content of various alkaloids in the plant is useful as a basis for chemotaxonomy.
25 citations
TL;DR: In this paper, 3-Sulfolenes serve as butadienyl anion equivalents and this stragegy has been applied to the preparations of substituted dienes and the total synthesis of natural products.
Abstract: 3-Sulfolenes are easily converted to the corresponding 1,3-dienes by cheletropic removal of SO2. In addition, the generation of 3-sulfolenyl anions are achieved under several reaction conditions. Therefore, 3-sulfolenes serve as butadienyl anion equivalents and this stragegy has been applied to the preparations of substituted dienes and the total synthesis of natural products.
24 citations
TL;DR: In this article, a four-connected net of vanadium oxygen polyhedra and phosphate tetrahedra is shown to have a crystal symmetry lower than those prepared from redox intercalation reactions, and the structural relationship with VOPO4·2H2O is discussed.
Abstract: Crystals of layered phosphate hydrates A(VOP04)2·nH2O (A = metal cation) have been grown under bydrothermal conditions. All compounds except trihydrates Pb(VOP04)2·3H2O and Ni(VOP04)2·3H2O consist of layers of vanadium phosphorus oxide with metal cations and water molecules between the layers. The layer is a four-connected net in which corner-sharing vanadium oxygen polyhedra and phosphate tetrahedra alternate. Most phases crystallize in crystal symmetry lower than those prepared from redox intercalation reactions. Their crystal structures and the structural relationships with VOPO4·2H2O are discussed.
21 citations
TL;DR: Significance from the chemotaxonomic viewpoint is discussed on the basis of previous studies and recent findings on the chemical constituents of Taiwanese liverworts.
Abstract: Significance from the chemotaxonomic viewpoint is discussed on the basis of previous studies and recent findings on the chemical constituents of Taiwanese liverworts.
20 citations
TL;DR: In this article, the dipole moments, polarizabilities, and hyperpolarizabilities of five molecules (HF, OCS, O3, CH3F, and CH3Cl) were computed at their experimental equilibrium geometries using the deMon density functional program.
Abstract: The dipole moments, polarizabilities, and hyperpolarizabilities of five molecules (HF, OCS, O3, CH3F, and CH3Cl) have been computed at their experimental equilibrium geometries using the deMon density functional program. For molecules of such sizes, we augmented the basis set of valence double-zeta plus polarization functions with field-induced polarization functions. Contamination of least-squares fitted parameters by higher-order hyperpolarizabilities have been greatly reduced by fitting the field-dependent dipole moments to eighth order polynomials using as many as 37 points per molecule. The results compare well with experiment.
20 citations
TL;DR: In this paper, the specificity of enzyme on different amino acids and the stability of both free and immobilized enzyme have been studied for the resolution of natural and unnatural amino acids using soluble or immobilized industrial enzyme "Alcalase" as catalyst.
Abstract: Procedures have been developed for the resolution of natural and unnatural amino acids using soluble or immobilized industrial enzyme “Alcalase” as catalyst. The specificity of enzyme on different amino acids and the stability of both free and immobilized enzyme have been studied.
19 citations
TL;DR: In this paper, a superconducting oxide with a stoichiometry La3CaBa3Cu7O15.5+x, in which x = 0.75, was prepared.
Abstract: A superconducting oxide with a stoichiometry La3CaBa3Cu7O15.5+x, in which x = 0.75, was prepared. It had a tetragonal triple-perovskite structure with lattice parameters a = 3.879 A and c = 11.637 A. According to resistivity measurements, a sharp superconducting transition, ΔTc(10-90%) = 1.5 K, and Tc(zero) = 80 K were observed. When it was measured at a small magnetic field (10-20 gauss) with field cooling, the sintered pellet showed a positive magnetic susceptibility, but the powdered sample exhibited (he diamagnetism of a typical superconductor. However, no peculiar shielding effect was found in both the sintered and powdered samples.
17 citations
TL;DR: By combination of centrifugal partition chromatography (CPC) and common separation methods, seven additional known bases were isolated and characterized from the reinvestigation of L. cubeba besides three previously isolated bases- isocorydine (10), N-methyllaurotetanine (9), and boldine (2).
Abstract: By combination of centrifugal partition chromatography (CPC) and common separation methods, seven additional known bases were isolated and characterized from the reinvestigation of L. cubeba besides three previously isolated bases- isocorydine (10), N-methyllaurotetanine (9), and boldine (2). They are laurolitsine (1), laurotetanine (3), isoboldine (4), norisocorydine (5), N-methyllindcarpine (7), isodomesticine (8), and glaziovine (6). Among these, compound 9 is the most abundant (7.5 × 10−4) and will be modified for pharmacological tests. This work will be of value for chemotaxonomy.
TL;DR: A series of 4-formyl-, 4-acetyl- and 4-(l'-hydroxyethyl) sydnones have been prepared in good yields by reaction of sydnone with butyllithium or a Grignard reagent as mentioned in this paper.
Abstract: A series of 4-formyl-, 4-acetyl- and 4-(l'-hydroxyethyl)sydnones have been prepared in good yields by reaction of sydnone with butyllithium or a Grignard reagent and N,N-dimethylformamide, N,N-dimethylacetamide and acetylaldehyde, respectively.
TL;DR: In the presence of a catalytic amount of 60% perchloric acid, 4-acetyl-3-substituted sydnones were obtained more conveniently with greater yields by the sonochemical reaction of 3 -substitized sydnone with acetic anhydride as discussed by the authors.
Abstract: In the presence of a catalytic amount of 60% perchloric acid, 4-acetyl-3-substituted sydnones were obtained more conveniently with greater yields by the sonochemical reaction of 3-substituted sydnone with acetic anhydride. Some 4-acetylsydnones which are difficult to synthesize by a known process were obtained in 17-68% yields.
4-Bromo-3-(bromoaryl)sydnones with activated zinc powder dispersed in methanol were debrominated regioselectively by ultrasound in high yields (60-96%). 3-(2′-/4′-Amino-3′,5′-dibromophenyl)sydnone is synthesized easily from 3-(2′/4′-aminophenyl)sydnone by reduction, bromination and debromination subsequently.
TL;DR: In this article, 2,5-dimethylene-2,5dihydrofuran (3) was generated pyrolitically, underwent di-and trimerization reactions to give cyclic dimer and trimer, and was trapped with methanol, ethanol, bromine, acetic acid, thiophenol and oxygen.
Abstract: 2,5-Dimethylene-2,5-dihydrofuran (3), generated flash pyrolitically, underwent di- and trimerization reactions to give cyclic dimer and trimer. Compound 3 was trapped with methanol, ethanol, bromine, acetic acid, thiophenol and oxygen. Results from trapping experiments suggest that the diradical form of 3 is involved.
TL;DR: In this paper, various derivatives of thiophene, thiazoline and thienopyrimidine were synthesized via the reaction of active methylene reagents with benzoyl isothiocyanate in the presence of potassium hydroxide, followed by the subsequent treatment of the potassium salt intermediates 2a-j with phenacyl bromide or ethyl chloroacetate.
Abstract: Various derivatives of thiophene, thiazoline and thienopyrimidine have been synthesized via the reaction of active methylene reagents (la-j) with benzoyl isothiocyanate in the presence of potassium hydroxide, followed by the subsequent treatment of the potassium salt intermediates 2a-j with phenacyl bromide or ethyl chloroacetate. The stability of the formed adducts 3 and 12 or their selective cyclization depends on both the nature of the active methylene reagent and the α-halocarbonyl compounds.
TL;DR: In this paper, a topological expression for the fourth spectral moment was derived for all molecular graphs. And the properties of a bound for total π-electron energy were established.
Abstract: Some properties of a bound for total π-electron energy are established. A topological expression for the fourth spectral moment is deduced, valid for all molecular graphs.
TL;DR: In this article, unsubstituted and substituted linear polythienyls including thiophenes in both even and odd numbers are conveniently prepared from the Michael addition of thiophenecarboxaldehydes to Mannich bases and the vinyl sulfone cyclization of the resulting 1,4-diones with Lawesson's reagent.
Abstract: Unsubstituted and substituted linear polythienyls including thiophenes in both even and odd numbers are conveniently prepared from the Michael addition of thiophenecarboxaldehydes to Mannich bases and the vinyl sulfone Cyclization of the resulting 1,4-diones with Lawesson's reagent gives α-polythienyls
TL;DR: In this article, an anti-selective synthesis of optically active α-amino acids from glycine via Schiff base employing (+)-N,N-diisopropyl-10-camphorsulfonamide as a chiral template is described.
Abstract: Enantioselective synthesis of optically active α-amino acids from glycine via Schiff base employing (+)-N,N-diisopropyl-10-camphorsulfonamide as a chiral template is described.
TL;DR: A review of spectral and kinetic studies of free radicals of atmospheric interest in this laboratory during the past decade is given in this paper, where the spectral experiments involved infrared absorption and laser-induced fluorescence in the UV-visible spectral region to detect radicals in a flow reactor, a supersonic jet or isolated in matrices.
Abstract: A review of spectral and kinetic studies of free radicals of atmospheric interest in this laboratory during the past decade is given. The spectral experiments involved infrared absorption and laser-induced fluorescence in the UV-visible spectral region to detect radicals in a flow reactor, a supersonic jet or isolated in matrices. IR absorption of several reaction intermediates and vibronic analyses of many electronic transitions have been reported. The discharge-flow and the laser-photolysis techniques were employed to investigate the kinetics of radical reactions which are important in the atmosphere; the temperature dependence of the rate coefficients was determined. Information on the rate coefficients of several important reactions has been reported. The detailed rate coefficients of some equilibrium reactions involving OH at various temperatures were determined from the bi-exponential temporal profiles of the concentration of OH; ΔH and ΔS of the reaction were consequently obtained.
TL;DR: In this article, the chemical constituents mainly include terpenes, lignans and flavones of conifers of Cupressaceae, Pinaceae and Taxodiaceae, of which endemic species such as Chamaecyparis taiwanensis and Taiwan white pine are emphasized.
Abstract: Chemical constituents of conifers of families of Cupressaceae, Pinaceae and Taxodiaceae, of which endemic species such as Chamaecyparis taiwanensis, Chamaecyparis formosensis, Calocedrus formosana, Pinus armandii, Tsuga chinensis and Taiwania cryptomerioides are emphasized. The chemical constituents mainly include terpenes, lignans and flavones. Methods and significance of this research are discussed. Extraction, crystallization and chromatography are general methods for separation of plant constituents. Chemical and spectral methods including IR, MS and NMR are frequently used for structural determination along with X-ray crystallography and circular dichroic spectroscopy to establish absolute configuration in appropriate cases. Finding hinokitiol from Taiwan cypress has initiated the emerging study of troponoid chemistry and nonbenzenoid aromatic compounds. A norsesquiterpene chamaecynone and a mixture of sesquiterpenes T-cadinol and T-muurolol exhibit respectively termiticide and antifidant activities. The flavonoid and stilbene constituents are analyzed to support the chemotaxonomy of armand pine and Taiwan white pine. A study of the constituents of armand pine indicates that 30-nor-3β-methoxyserrat-14-en-21-one is biogenetically derived from 3β-methoxyserrat-14-en-21-one by an oxidative degradation via intermediacy of the 30-alcohol and the 30-aldehyde.
TL;DR: In this article, the reaction of trimethylbenzene (TMB) over alumina-pillared montmorillonite (Al-PM) was investigated in a fixed-bed flow reactor at 300 °C and atmospheric pressure.
Abstract: The reaction of trimethylbenzene (TMB) over alumina-pillared montmorillonite (Al-PM) had been investigated in a fixed-bed flow reactor at 300 °C and atmospheric pressure. Al-PM calcined in the range 300-500 °C exhibited decreased layer distance, surface area and acid amount. The strong acid sites of Al-PM calcined at 500 °C were greatly diminished according to measurements of ammonia temperature-programmed desorption. Under our conditions the reaction proceeded mainly via isomerization and disproportionation with little dealkylation. The conversion of reactant decreased in the order 1,2,3-TMB ≥ 1,2,4-TMB > 1,3,5-TMB and the selectivity of isomerization in the order 1,2,3-TMB > 1,3,5-TMB > 1,2,4-TMB, corresponding to the order of diminishing thermal instability. Both the catalytic activity and the selectivity ratio of disproportionation to isomerization decreased with increased calcined temperature and time-on-stream. o-Xylene content in the total xylene produced from 1,2,4-TMB or 1,2,3-TMB greatly exceeded the composition at thermodynamic equilibrium. These results arc consistent with the decrease of both the strong acid sites and the pore size of Al-PM which exhibits the restricted transition state selectivity.
TL;DR: In this article, the effects of cross-correlation in homo- and heteronuclear spin systems are investigated. But the application of null point spectral analysis to biological systems is not discussed.
Abstract: Two aspects of NMR relaxation are reviewed and their use in studying molecular dynamics in the liquid state and their application to biological systems are discussed. The first aspect concerns the use of ‘null-point spectra’ for observing the effects of higher rank multipoles (tensors) in the relaxation of quadrupolar nuclei. The second aspect concerns the effects of cross-correlation in homo- and heteronuclear spin systems. The application of null point spectral analysis to study cross-correlation in homonuclear spin systems is also discussed. Analysis of the effects of higher rank multipoles and of cross-correlation effects are shown to provide substantially more structural and motional information about spin systems than that available from traditional relaxation measurements. While similar in information content to multiple quantum techniques, the null point technique is experimentally less demanding. Over the past several years, work in this laboratory has been heavily involved in the theoretical formulation and the application of these techniques to biological systems. Illustrations of the use of these techniques to biological systems are drawn from our recent work.
TL;DR: The results of detailed examinations on the comparison of Hammett-type correlation analysis of solvolytic rate constants with single and dual-parameter equations are summarized in this article.
Abstract: The results of detailed examinations on the comparison of Hammett-type correlation analysis of solvolytic rate constants with single- and dual-parameter equations are summarized. From the difference of ρ values, the variation of γ values with numbers of data points, the solvent intervention in the standard reactions for defining σ+ constants, the influence of o-methyl group on the reactivity of the reference substrate (tert-cumyl derivatives), and the behavior of the α-aryl group in highly congested systems, it could be concluded that both the Hammett-Brown and the Yukawa-Tsuno treatments of solvolytic rate constants are only approximations. Although in some cases the use of the dual-parameter Yukawa-Tsuno equation (Eq. 4) could give a better correlation and a more proper explanation than the use of the single-parameter Hammett-Brown equation (Eq. 2), in other cases the excellent correlation observed from the former might be merely a computational artefact. Therefore, the result obtained from the Yukawa-Tsuno equation should be interpreted with caution.
Abstract: Irradiation of quinoxalinobarrelenes 3 and 4 afforded quinoxalinosemibullvalenes via vinyl-vinyl and quinoxalino-vinyl bridgings, the former being the major route. No reaction occurred upon prolonged irradiation of (benzo[g]quinoxalino)barrelenes 5 and 6.
TL;DR: In this paper, the structure was solved by direct method, 3996 unique reflections having I > 3σ(I) measured with an automated diffractometer were used to refine the crystal structure to a conventional R factor 0.0431.
Abstract: X-ray diffraction data and NMR spectra of diperchloratotetraphenylporphinatotin(IV), Sn(tpp)(ClO4)2 provide evidence for a monodentate perchlorato group coordinated to the Sn(IV) atom. The molecule Sn(tpp)(ClO4)2 displays an octahedral coordination geometry for the tin atom and its crystal belongs to the monoclinic space group P21/n with a = 11.241(3), b = 14.644(3), c = 12.173(3) A,β = 111.18(2)°, and Z = 2. The structure was solved by direct method, 3996 unique reflections having I > 3σ(I) measured with an automated diffractometer were used to refine the crystal structure to a conventional R factor 0.0431. The tin(IV) ion is centered on a planar tpp moiety. The geometry at the octahedral coordination centre of the Sn(tpp) (ClO4)2 molecule has Sn-O(perchlorate) = 2.181 A and Sn-N = 2.073 A.
TL;DR: In this paper, high-resolution 13C NMR spectra of bovine brain sulfatide, egg sphingomyelin, and cholesterol/phosphatidylcholine dispersions were obtained by the cross-polarization/magic angle spinning (CP/MAS) method as functions of contact time, temperature and composition.
Abstract: Solid-state high resolution 13C NMR spectra of bovine brain sulfatide, egg sphingomyelin, egg phosphatidylcholine, and cholesterol/phosphatidylcholine dispersions were obtained by the cross-polarization/magic angle spinning (CP/MAS) method as functions of contact time, temperature and composition. Quantitative analysis of the chemical shift and linewidth data indicate that in the liquid-crystalline state the hydrocarbon chains of sulfatide are packed less orderly than those of sphingomyelin, and that there are two or more conformers for the ceramide residues of natural sphingolipids. The fatty acid double bond showed higher mobility than that of sphingosine as monitored by the signal intensity profiles as a function of contact time. The same approach was used to study the coexisting Lα (liquid-crystalline phase) and β (cholesterol-rich characterized phase) two-phase region of cholesterol/phosphatidylcholine mixtures. Without isotope enrichment, structural and phase properties of natural lipid dispersions can be obtained easily by monitoring the chemical shift, the signal intensity and the linewidth of l3C NMR spectra.
TL;DR: In this article, a computer adapted vector method and Euler angle transformation procedures are used to generate the relationship between the atomic orbitals of icosahedral C60 Buckminsterfullerene cluster and to produce symmetry adapted molecular orbitals and vibrational species.
Abstract: A computer adapted vector method and Euler angle transformation procedures are used to generate the relationship between the atomic orbitals of icosahedral C60 Buckminsterfullerene cluster and to produce symmetry adapted molecular orbitals and vibrational species. The atomic overlaps based on the orientational relationship of the orbitals are used to compute the approximate molecular orbital energies and normalization constants. One of the vibrations of Au, symmetry is used to interpret the isomeric (dyotropic) rearrangement that breaks and forms two bonds to change two pentagons to two hexagons and vice versa.
TL;DR: In this article, the first example of a ferrocenyl ligand having both sulfur and phosphorus donor atoms bound to a Fe(CO)3 moiety was presented, which was solved according to the heavy-atom method and refined by full-matrix least-squares procedures to R = 0.037 for 2098 reflections with I ≥ 2.5σ(I).
Abstract: The complex (ptppf)Fe(CO)3 has been prepared in high yield by the reaction of ptppf, l-(diphenyl-phosphino)-l'-(phenylthio)ferrocene, with (cis-cyclooctene)2-Fe(CO)3 in THF at −60°C. The complex has been characterized by IR, 31P NMR, mass spectrometry and single-crystal X-ray diffraction. This compound is the first example of a ferrocenyl ligand having both sulfur and phosphorus donor atoms bound to a Fe(CO)3 moiety. X-ray crystallography shows that the two cyclopentadienyl rings are approximately eclipsed, a rotation of 13° from exactly eclipsed conformation. The tricarbonyl iron center has a trigonal bipyramidal geometry with sulfur occupying the equatorial site and phosphorus the axial site. Crystals of (ptppf)Fe(CO)3 are monoclinic, with a = 11.645(2), b = 14.304(1), c = 17.075(2) A,β = 109.23(3)°, Z = 4, and space group P 21/n. The structure was solved according to the heavy-atom method and refined by full-matrix least-squares procedures to R = 0.037 for 2098 reflections with I ≥ 2.5σ(I).
TL;DR: In this paper, a hydride generation-atomic absorption spectrometry (HG-AAS) procedure is described for the analysis of tributyltin (TBT) in sea water.
Abstract: A hydride generation-atomic absorption spectrometry (HG-AAS) procedure is described for the analysis of tributyltin (TBT) in sea water. TBT is first converted to its volatile hydride form by reaction with sodium borohydride, followed by cryogenic trapping at −196°C, and finally detection by atomic absorption spectrometry using an electrically heated quartz atomization cell. The linear range of calibration is 5-250 ng TBT (as tin). At the 5-ng level, the relative standard deviation (RSD) is 13%. The absolute detection limit (3σ) is 1.8 ng. Based on a sample volume of 500 mL, this value corresponds to a concentration detection limit 3.6 ng L−1 TBT This method has been successfully applied to the analysis of TBT in sea water collected from Keelung and Kaohsiung harbors.