bluuebunny/crossref_metadata_2025_split huggingface dataset:
HPLC Determination of Amino And Carbonyl Compounds with Dabsyl Chloride and Dabsyl Hydrazine
Authors: Lin Jen‐Kun , Chang Su‐Chen , Huang Chian‐Chyi 
Published: June 2015

AbstractThe new chromophoric reagent, 4‐dimethylaminoazobenzene‐4′‐sulfonyl chloride (dabsyl chloride) was synthesized by reaction of sodium 4‐dimethylaminoazobenzene 4′‐sulfonate with phosphorus pentachloride. Dabsyl chloride reacted rapidly with all amino acids, aliphatic amines, and polyamines to form the corresponding dabsyl derivatives. The dabsyl amino acids (10−11 mol) were visualized on thin layer plates and found to be photo‐stable. During the last 12 years, in combination with HPLC, this newly developed labeling reagent has been shown to be very promising for microdetermination of amino acids, aliphatic amines and polyamines.Recently, another new chromophoric reagent, dabsylhydrazine, was synthesized from the reaction of dabsyl chloride with hydrazine. This reagent reacted readily with monosaccharides and carbonyl compounds to form the corresponding chromophoric dabsylhydrazones with strong absorbance at 425 nm. The application of this new reagent in HPLC analysis of monosaccharides was discribed. By use of Nova‐PAK C18 reverse‐phase column and a concave gradient system of water and acetonitrile as eluent, the detection limits of monosaccharides in the range of 10 pmol have been reached.
Synthesis on Al‐Mg Polynuclear Bridged‐Complexes (I): Reactions of Aluminum‐Trialkoxide with Magnesium‐Di‐N‐Butyl
Authors: Chang Chung‐Cheng , Chang Mei‐Yen , Cheng Cheu‐Pyeng 
Published: June 2015

AbstractThe reaction of magnesium di‐n‐butyl with alumium trialkoxide (R=C2HS, Sec·C4H9) gave the major product [Bu2Mg Al(OR)3]2. which was characterized by elemental analysis, mass spectral data, infrared data and 2D‐nuclear magnetic resonance spectral data. The nmr spectral data indicated that the most likely structure of the major products were cyclic with bridging butyl and alkoxide groups.
Mass Spectra of Acridone Alkaloids
Authors: Lin Shaw‐Tao , Wu Tian‐Shung 
Published: June 2015

AbstractThe mass spectra of a variety of simple acridones, prenylacridones, pyranoacridones, dihydropyranoacridones, and furoacridones are presented and discussed. The results illustrate that the characteristic fragmentation patterns are of considerable utility in the application of mass spectrometry to structure elucidation in the acridone alkaloids.
Studies of the Deposit Formation on Storage of a High Energy Fuel
Authors: Wang S. M. , Li N. C. , Chang H. , Huang P. J. 
Published: June 2015

AbstractStorage stabilities of a petroleum‐derived jet fuel (JP‐5), manufactured by the Chinese Petroleum Corporation in Taiwan, were studied. Fuel degradation was monitored in the presence of added specific heteroatomic (O, N, S) and unsaturated compounds, copper, iron and aluminum powders and mixtures of some of these at room temperature and 80°C. A mechanism is suggested for the sediment formation with the sulfur compounds. The extent of light scattering and of metal drawn into JP‐5 from added metal powder measured by ICP‐AES are correlated with the extent of deposit formation in degradation of the fuel. Metal promotes deterioration of JP‐5, because of metal complex formation.
Symmetry and Intervalent Charge Transfer in Copper‐Oxide Superconducting Precursors
Authors: Chiu Ying‐Nan 
Published: June 2015

AbstractA vibrationally coupled intervalent charge transfer theory is proposed for the copper oxide‐superconductors. The proposed B1g‐vibrational distortion exactly interchanges the chemical environment of the neighboring copper atoms. A quadruple cell is constructed to accommodate the non‐stoichiometry and a double copper‐oxide‐conducting chain with distorted symmetry is postulated. The distorted structure, prone to switching of the copper sites by vibration, is postulated to be the superconducting precursor. The left over‐oxygen, due to oxygen deficiency, is allowed to serve as a bridge between the chains and 10 oscillate with the vibration. Symmetry of the system, before and after distortion, is used to explain the spin‐angular momentum change, needed to arrive at Cooper‐paired electron/holes. The O− and O= atoms are postulated to be the bridge for superexchange and charge flow between the Cu+1/Cu+3 and Cu+1/Cu+2 pairs. The same theory is used to interpret the mechanisms for the following three types of copper oxide‐superconductors: YBa2Cu3OT‐x; La2‐xSrxCuO4 and the newly discovered electron superconductor Nd2‐xCexCuO4‐y. The bridge oxygen oscillation may be chosen not to come from the breathing mode but from the bending deformation mode that involves the relative motion of the Cu atoms (to the oxygen) giving rise to smaller oxygen isotope effect.
Cylic Voltammetric Studies on the Electrode Reaction of Polyacetylene Secondary Cell
Authors: Wang Jeng‐Jong , Chen Shou‐Nan , Chen Ying‐Chung 
Published: June 2015

AbstractCells of lithium / Polyacetylene containing 0.5 · 1.5 M LiClO4 in propylene carbonate as supporting electrolyte are constructed. The mechanism for electrochemical redox process of polyacetylene is studied using cyclic voltammetry in the potential range from −0.8 to 0.2 volt vs. S.C.E. The electrode reactions are identified to be diffusion controlled. The difference of the peak potentials between the oxidation and reduction, ΔEp, is found to be a function of the scan time per cycle (τ sec/cycle) and is influenced by concentration of supporting electrolyte and isomeric structures of polyacetylene. However, there is a better reversible redox process of polyacetylene when the ClO4− ‐ ions diffuse successfully in and out of the Polymer film, which has the cis‐form structure, in concentrated supporting electrolyte solution and having a long scan time per cycle (τ). When the scan potential is extended to a more positive region, another peak is found, which may correspond to the irreversible chemical reaction caused by over‐doping. The over‐doping process is found to be controlled by the electrical field strength, concentration of the supporting electrolyte and isomerism of polyacetylene.
The Interaction of Oxygen with Silver Powders. A Comparison Between Esca Results and Volumetric Measurement
Authors: Chen Jr‐Jyan , Cheng Chi‐Fong , Yeh Chuin‐Tih 
Published: June 2015

AbstractInteractions of oxygen with silver powders have been studied with a combination of angle‐resolved ESCA and volumetric adsorption. Three states of adsorbed oxygen, i.e., atomically adsorbed oxygen, dissolved oxygen, and surface oxide, are characterized by 0(1s)‐ESCA peaks at binding energies of 530.2, 532.0, and 529.3 eV respectivcly. The ESCA studies also suggest that atomically adsorbed oxygen dissolves into the subsurface of silver powders at temperatures above 100 °C, and then transforms into oxide (Ag2O) at 175 °C. Adsorbed oxygen on the silver powders was partially desorbed at temperatures higher than 180 °C. The transformation and desorption information obtained from ESCA satisfactorily explains the variation of the adsorption isotherm with temperature obtained from the volumetric adsorption of oxygen on Ag/SiO2 catalysts.
Role of Modern Analytical Chemistry in Material Analyses for Trace Metals
Authors: Rains Theodore C. 
Published: June 2015

AbstractThe trend in the modern analytical laboratory is toward lower and lower analytical concentration measurements. The analyst has a variety of analytical instruments and techniques in which to meet the ever growing need for lower concentration measurements with improved precision and accuracy. Techniques available to the analyst include flame and electrothermal atomization‐atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma/mass spectrometry, laser enhanced ionization spectrometry, neutron activation analysis, spectrophotometry, isotope dilution mass spectrometry, X‐ray fluorescence spectometry, electroanalytical, and chromatography. However, there is no analytical technique that is a panacea for all analytes in the modern analytical laboratory. Steps the analyst must consider to obtain the highest degree of precision and accuracy include the obtaining of a representative sample, the selection of the “best” analytical method, the preparation of the sample, the calibration of the instrumentation, the deciding on the level of effort for the chemical measurement and the evaluation of the data are discussed.
Reactions of 2,3‐Butanedione Monoxime with Diamine Compounds
Authors: Wang Yun‐Ming , Chung Chung‐Sun , Ting Gann 
Published: June 2015

AbstractA number of diazadioximes have been prepared by reactions of the corresponding diamines with 2,3‐butanedione monoxime in the presence of p‐toluenesulfonic acid or in ethanol.
Mixed Titanium and Phosphorus Oxides. II. — The Effect of pH Values of Solutions on Surface Acidity
Authors: Huang Chun‐Lan , Cheng Soofin 
Published: June 2015

AbstractA series at mixed oxides of titanium and phosphorus were prepared by co‐precipitation method accompanying refluxing treatment. The effect of the pH values of the solutions on the structures, compositions, and surface acidities of the resultants compounds was determined. The samples were characterized by BET surface area measurement, X‐ray powder diffraction (XRD) for structural analysis and amine‐titration for surface acidities. After calcinating the oxides at 773 K, the surface acidities were attributed mainly to Ti(OH)PO4 structure. Elemental analysis revealed that the P/Ti ratios in the samples decreased with increasing the pH value of the preparative solution. When the mixed oxides were used as catalysts for 2‐propanol decomposition reaction, the highest activities were obtained over the samples prepared in the solutions with the pH values being 2 or 3. That result was in agreement with the variation in surface area and acid amount of the catalysts.
Preconcentration of Trace Elements in Water for Speciation Studies
Authors: Mizuike Atsushi 
Published: June 2015

AbstractTrace element speciation has recently become one of the most important problems in water analysis. Proper combination of preconcentration techniques with instrumental determination methods is essential to speciation analysis, because sensitivity and selectivity of direct determination methods are generally lacking. The present paper describes such preconcentration techniques as filtration, centrifugation, flotation and sorption, which have been developed in the author's laboratory for the speciation of heavy metals in river and pond waters by electron microscopy, X‐ray microanalysis and chemical analysis. The application of freeze concentration to the speciation of silica in high‐purity waters is also discussed.
A New Pentacyclic Triterpene from Ecdysanthera Rosea
Authors: Huang Keh‐Feng , Sy Maa‐Lih , Lai Jeng‐Shiow 
Published: June 2015

AbstractD‐friedours‐14‐en‐11α, 12α‐epoxy‐3β‐yl palmitate (1), a new pentacyclic triterpene of the ursane series, was isolated from the aerial parts of Ecdysanthera rosea, and the structure was elucidated on the basis of the spectral data. The partial synthesis of this compound from α‐amyrin acetate via a few steps was also achieved.
Characterization of Anilinepentacyanoferrate (II) and (III)
Authors: Chao Feng‐Hsien , Sun Bin‐Kuo , Juang Po‐Chuang , Yeh Andrew 
Published: June 2015

AbstractThe anilinepentacyanoferrate (II) complex has been characterized in aqueous solution. The complex exhibits a predominant ligand field transition at λmax = 415 nm with ϵmax = 494 M−1 cm−1. The corresponding Fe(III) complex displays a strong absorption at λmax = 700nm(ϵmax = 1.61×104 M−1 sec−1) which can be assigned as a ligand to metal charge transfer transition. The rate constants of formation and dissociation for the Fc(II) complex are (3.14±0.18)×102 M−1W−1 and 0.985±0.005 sec−1, respectively, at μ = 0.10 M LiClO4, pH = 8 and T = 25°C. The cyclic voltammetry of the complex shows that a reversible redox process is observed with E1/2 value of 0.51±0.01 V vs. NHE at μ = 0.10 M LiClO4, pH = 8 and T = 25°C. The kinetic study of the oxidation of the Fe(II) complex by ferricyanide ion yielded the rate constant of the reaction ket = (1.43±0.04)x10 M sec−1 at μ = 0.10 M LiClO4, pH = 8 and T = 25°C.
The Micellar Dissociation Concentration of Polyoxyethylene Mono N‐Decylether Nonionic Surfactants in Water
Authors: Chiu Ying‐Chech , Chang Cheng‐Yen 
Published: June 2015

AbstractThis paper will demonstrate a method for determining the micellar dissociation concentration (MDC) of polyoxyethylene mono n‐decylether nonionic surfactants in water. Turbidity and surface tension measurements were applied to commercial samples without further purification. Complicated curves containing turbidity maxima and surface tension minima were obtained for some impure samples. It is difficult to determine the critical micellar concentration (CMC) for impure surfactants. Explanations are given for all curves obtained for pure and impure samples and the method of identifying the MDC values is illustrated. It is more practical for surfactant users to determine the MDC values in their own laboratory than to search for the CMC values in the literature when the surfactants arc impure.
The Polarographic Reductions of 4‐Cyano‐3‐Substitutedsydnones
Authors: Wang Lai‐Hao , Tien Hsien‐Ju 
Published: June 2015

AbstractThe reducing behaviors of five 4‐cyano‐3‐substitutedsydnones were studied with dropping mercury electrode. Their reducing potentials obey the modified Hammett equation and possible reaction mechanisms are discussed.
Keto‐Enol Tautomeric Equilibrium in 4‐Oxo‐1,1,3‐Cyclohexanetricarboxylic Acid Trialkyl Esters and 4‐Oxo‐1, 1, 3‐Cyclopentanetricarboxylic Acid Trialkyl Esters
Authors: Yang Chia‐Hsi , Yu Hwa , Wu Jiin‐Sheng 
Published: June 2015

Abstract4‐Oxo‐1,1,3‐cyclohexanetricarboxylic acid trialkyl esters in deuterochloroform and dimethylsulfoxide‐d6 (DMSO) exist exclusivly in the enol form. The keto form is the major component in the analogous compounds of five‐membered ring. The 1, 3 interaction between carboalkoxy groups in the six‐membered ring should be the reason why the carboalkoxy group at 3‐position is in equatorial configuration and engages in the intramolecular hydrogen bond, so that the enol form is dominating.
On the Electrochemical Reduction of α‐Cyanothioacetamide Derivatives (I) Polarographic Behaviour of 2‐Arylhydrazono‐2‐Cyanothioacetamides
Authors: Abdel Aziz Mahfouz A. , Fahmy Hussein M. , Azzem Magdi Abdel , Hathoot Abla A. 
Published: June 2015

AbstractThe polarographic reduction of a series of 2‐aryl‐hydrazono‐2‐cyanothioacetamides ((Ia‐e) has been examined in 50% ethanolic buffer solutions. The obtained data indicate that these compounds are in the hydrazono form and that they are reduced to give an amino acid and the corresponding primary aromatic amine. A mechanism has been proposed and discussed. Recombination and dissociation rate constants (kr) and (kd) have been computed using the appropriate spectrophotometric, potentiometric and apparent acid equilibrium constants.
Mössbauer Spectra and Magnetic Properties of Polydiimine Complexes of Iron(II) Sulfate
Authors: Sheu Jinn‐Fu , Wei Ho‐Hsiang , Yao Yeong‐Der 
Published: June 2015

AbstractA new series of polynuclear iron complexes with polydiimine ligand have been prepared from the Schiff‐base condensation of pyridine‐2, 6‐dialdehyde or 2, 6‐diacetylpyridine with aliphatic diamines. The structures of the complexes are represented by [−N = CR‐Py‐CR = N‐(CH2)n‐]2FeSO4·xH2O; where R = H, CH3; n = 4−10, × = 5∼8. Mössbauer spectra and magnetic measurements show several complexes have unusual magnetic properties.
Study on the Nucleophilic Addition to (η4‐Cis‐1‐Methoxy‐1,3‐Butadiene)Iron Tricarbonyl Complex
Authors: Yeh Ming‐Chang P. , Chu Chih‐Hong , Sun Mei‐Ling , Kang Kuo‐Ping 
Published: June 2015

AbstractReaction of the reactive carbanion with (η4‐cis‐l‐methoxy‐1,3‐butadiene)Fe(CO)3, followed by acid quenching, generates the C‐1 substitution product (27%) together with the regular C‐2 adduct (71%). A very stable ferracyclopentanone was isolated and its x‐ray diffraction analysis determined.
The Mass Spectra of 4‐(3‐Arylsydnonyl)Methanols and Their Derivatives: Formation of Ar‐N=C‐H Cation via a Hydrogen Migration
Authors: Shaw‐Taolin  , Tien Ling‐Ling 
Published: June 2015

AbstractFourteen mass spectra of the sydnonylmethanols and their derivatives have been measured under EI conditions. The process of losing a OR' radical and hydrogen migration reaction are accompanyed with lost of a CO and an NO channel. The competition between cleavage of C‐0 bond and hydrogen migration is mainly controlled by the type and size of the R' group.
Synthesis of (±) Peperomins
Authors: Zee Sheng‐Hsu , Chou Shan‐Yen 
Published: June 2015

AbstractThe total synthesis of natural antitumor agent (±) peperomin A, B and C are reported. These syntheses were started from benzophenones and diethyl succinate by Stobbe condensation. Three successive steps were employed to give the (±)‐peperomins.
Kinetics of the Electron‐Transfer Reactions between (Ethylenediaminetetraacetato) Cobaltate (III) and (4‐Aminopyridine)Pentacyanoferrate (II) Complexes
Authors: Lin Charng‐Sheng , Chien Chiu‐Feng , Yeh Andrew 
Published: June 2015

AbstractKinetic measurements for the forward reaction Fe(CN)54‐AmPy3− + Co(edta)− ⇌ Fe(CN)5s4‐AmPy2− + Co(edta)2− have been carried out; the rate constant is 2.72 ± 0.07 M−1s−1, at pH = 8, μ = 0.10 M LiClO4, and T = 25°C. The activation parameters of the reaction were also studied with and . The mechanism of the reaction is discussed in the context of the Marcus cross relation for an outer‐sphere process.
Cleavage of C‐S Bond of Sulfolane Induced by Ultrasonically Dispersed Potassium
Authors: Chou Ta‐Shue , Hung Shao‐Hwa , Peng Man‐Li , Lee Shwu‐Jiuan 
Published: June 2015

AbstractThe reductive cleavage of the carbon‐sulfur bond of sulfolane has been reinvestigated; a reaction mechanism is proposed.
Substituent Effects on Phosphate‐Catalyzed Proton Exchange in Amides
Authors: Wang Wei‐Hsien , Cheng Ching‐Chih , Lee Ming‐Chao , Huang Chiung‐Yi 
Published: June 2015

AbstractThe kinetics of phosphate‐catalyzed proton exchange have been measured with NMR lineshape analysis for a series of amides, ureas, and carbamates. A hypothetical energy profile for transition structures of concerted phosphate catalysis ‡c and of stepwise phosphate catalysis ‡1, ‡2 is used for discussion of the substituent effects. The concerted mechanism of phosphate catalysis operates only for amides RCONHCH3 for which the electron‐donating ability of the substituent R is comparable with, or better than, that of the methyl group. We conclude that concerted phosphate catalysis is inoperative in proteins or polypeptides.
Cleavage of (–)‐Eschscholtzine with Sodium in Liquid Ammonia
Authors: Lee Shoei‐Sheng , Lin Chia‐Yin , Chen Chung‐Hsiung 
Published: June 2015

Abstract(–)‐Eschscholtzine was cleaved with sodium in liquid ammonia to yield 2,8‐dihydroxy‐N‐methylpavine and 2,9‐dihydroxy‐N‐methylpavine. This reaction indicates regioselectivity by cleavage mainly at a site para to the methine carbon of a bridgehead.
Reaction of Tricarbonyl(η3‐allyl)iron(0) Anions with Bromine
Authors: Yeh Ming‐Chang P. , Kang Kuo‐Ping , Hwu Chong‐Chen 
Published: June 2015

AbstractThe addition of reactive carbanions to tricarbonyl(η4‐1,3‐diene)iron(0) complexes proceeded at 23°C to give putative tricarbonyl(η3‐allyl)iron(0) anion complexes. Trapping of the reactive intermediates with bromine produced nucleophilic‐substituted tricarbonyl(η4‐1,3‐diene)iron(0) complexes.
Synthesis of Novel 7‐Allyl‐8‐Substituted Guanosines
Authors: Come J. , Klaubert D. H. , Chen R. 
Published: June 2015

AbstractA useful one‐pot procedure for preparing certain novel 8‐subsituted guanosine derivatives from 7‐allyl‐8‐thioxoguanosine (2b) has been developed.
Isolation of 24‐Hydroperoxy‐24‐Vinylcholesterol and Fucosterol from the Brown Alga Turbinaria Conoides
Authors: Sheu Jyh‐Horng , Sung Ping‐Jyun 
Published: June 2015

AbstractA highly cytotoxic hydroperoxysterol 24‐hydroperoxy‐24‐vinylcholesterol (1) and fucosterol (2) were isolated from the brown alga Turbinaria conoides. Compound (1) was transformed into 29‐hydroperoxystigmasta‐5, 24(28)‐dien‐3β3‐ol 3 in chloroform solution at −5–0°C in quantitative yield. The latter compound has been shown to exhibit much stronger cytotoxicity toward cultured spleen lymphocytes stimulated by mitogen concanavalin A than toward normal spleen lymphocytes.
Layered Group(IV) Metal Phosphates as Catalysts for MTBE Synthesis
Authors: Cheng Soofin , Wang Jee‐Ten , Lin Chun‐Liang 
Published: June 2015

AbstractLayered group(IV) metal phosphates and their phenylsulfonic acid derivatives were used as catalysts for the synthesis of methyl tert‐butyl ether (MTBE) from methanol and isobutene. Because zirconium and titanium phosphates have only moderate acidic strength, relatively high temperatures are required to activate their Brønsted acidic sites. The optimal activity was obtained at ca. 443 K. Their phenylsulfonic acid derivatives, however, demonstrated higher acidic strength by giving much higher activity toward MTBE formation at relatively low temperaures. The catalysts were characterized in terms of their structure, thermal stability, surface area and acidic strength.
Investigation of Substituent Effects on Proton and Carbon‐13 Chemical Shifts of 4‐Substituted Trans‐Stilbenes
Authors: Gahm Kyung‐Hyun , Eng Siew‐Leng , Ho Tong‐Ing , Lin Ying‐Chih 
Published: June 2015

AbstractProton and carbon‐13 chemical shifts of para‐substituted stilbenes have been measured. 1H‐1H, 1H‐13C COSY spectra were obtained to analyze unambiguously the chemical shifts of protons and carbons. A long range coupling between 2‐H and α‐H was observed in a 1H‐1H COSY spectrum. The observed chemical shifts have been correlated with Hammett substituent parameters. Among ethenyl protons and carbons, all but the chemical shifts of α‐H show good correlation with both dual substituent parameters and single substituent parameters. In addition to this finding, the excellent linear correlations of C‐l, and 4′‐H of 4‐substituted trans‐stilbenes are also reported. Besides the correlations of chemical shifts with Hammett parameters, a good correlation between the chemical shifts and the calculated charges of position C‐4′ are reported.
Improved Theoretical Spectrum of Quasibound States and Resonances for H2(1∑g+)
Authors: Jiann‐Shing Shyu 
Published: June 2015

AbstractThe most recent ab initio potentials for H2(1∑g+), which include relativistic, adiabatic and radiative corrections, were used to calculate the spectrum of quasibound states. The levels, widths and tunneling permeability of resonant states were also studied by the quantum phase‐shift method. A new set of relevant resonance states for the calculations of atomic recombination of hydrogen is indicated by the present work. In comparison with the previous studies, significant improvements have been found for the resonances.
Micelles of SDS Surfactants in Concentrated NaCl Solutions
Authors: Lo Jin‐Hsiang , Mou Chung‐Yuan 
Published: June 2015

AbstractWe investigated the aggregation behavior of rod‐like micelles of sodium dodecyl sulfate (SDS) in concentrated NaCl solution by quasi‐elastic light scattering (QLS) and viscosity measurement over a range of temperature (25 °C to 50 °C) and NaCl concentration. The reduced viscosity of aqueous SDS in the presence of NaCl has been measured by an Ubbelohde‐type capillary viscometer. We show mean hydrodynamic radius of micelles can be determined from viscosity data. We also determined mean hydrodynamic radius using quasi‐elastic light scattering. Micellar size decreases with increasing temperature, whereas it increases with increasing ionic strength. The results of viscosity and dynamic light‐scattering measurements are interpreted as the extension of length of rod‐like micelles. We compare viscosity and light scattering experimental results.