bluuebunny/crossref_metadata_2025_split huggingface dataset:
Charge Separation in Triafulvenes: Application of the Para‐Fluorophenyl Tag 19f NMR Method
Authors: Agranat Israel 
Published: June 2015

AbstractTriafulvene (1) is the simplest [n]fulvene. Interest in triafulvenes centered on the potential contributions (in the ground state) of dipolar ‘aromatic’ structures of the type la, in which three‐membered ring assumes ‘cyclopropenium’ character2‐5). Various attempts have been made to increase these dipolar contributions by introducing electron withdrawing substituents at the exocyclic carbon atom (C4) of the triafulvene skeleton2‐6). A striking illustration of this trend is the study of the triapentafulvalene (2) system, motivated by the search for aromatic ‘cyclopropenium‐cyclopentadienide’ structures (2a)3). Cyclopropenone (3), the simplest [n]annulenone, may also fall within the category of triafulvenes formally being viewed upon as 4‐oxatriafulvene with a potential contribution of a cyclopropenium oxide (3a) structure to the ground state resonance hybride5,7,8).
Essential Oils XVII. Oil of Pogostemon Formosanus Oliv. II Isolation and Chemistry of Germacrone
Authors: Yeh Ping–Hsien 
Published: June 2015

AbstractThe crystalline product from the essential oil of Pogostemon formosanus, Oliv. was identified as 10‐membered ring seequiterpene ketone germacrone. Chemistry of germacrone was reinvestigated and reviewed. On the basis of the spectroscopic evidence and of the orbital symmetry rule, trans, trans‐configuration was assigned to germacrone.
Polarography of 4‐Nitrophthalic Acid
Authors: Sharma S. K. 
Published: June 2015

AbstractThe–NO2 group reduction in 4‐nitrophthalic acid (NPA) at dropping mercury electrode over a wide range of PH, is irreversible and diffusion controlled. Ill defined waves preceded the —NO2 group wave, were observed between PH 7 and 12 whereas at PH 5.0, a rounded maximum appears. The a. c. reduction of NPA at PH 12.0, provides two peaks, first peak corresponds to d. c. pre‐step, is essentially due to adsorption phenomena whereas other peak is the reduction wave. Using McBain Down cell and King‐cathcart equation the diffusion coefficient of NPA is 0.713×10‐3 cm2sec‐1. Six electrons are being involved in nitro group reduction and mechanism of the reduction was suggested. The kinetic parameters in absence and presence of ionic and non‐ionic surfactants were determined. The reduction process becomes more and more irreversible as surface activity of organic compounds increases. Ionic surfactants are effective in increasing the value of —log K° than the non‐ionic surfactants. The value of ana decreases regularly by the presence of compounds having regular increase of surface activity.
Pariser‐Parr‐Pople SCF MO Calculation on the Sydnone Ring
Authors: Wen Chung‐Ming , Tien Hsien‐Ju 
Published: June 2015

AbstractThe repulsive bond order of the sydnone ring between 2‐ and 4‐positions is very high negative and the π‐charge density carbon atom of position 4 is very small. The structure of sydnone ring are both dipolar form and mesoionic form.
Determination of Thorium and Total Rare Earths in Monazite Sand with Fluoride Electrode
Authors: Chang Fu‐Chung , Tsai Hui‐Tuh , Wu Shaw‐Chii 
Published: June 2015

AbstractA new method has been proposed to determine the total rare earths and thorium in monazite sand with fluoride electrode. The total amount of thorium and rare earths could be determined by back‐titration with standard lanthanum solution in excess fluoride, and the rare earths were titrated directly with fluoride from separate sample. Fluoride electrode was used as indicator electrode. Precision and accuracy were improved by Gran's plot technique.
A Spectrophotometric Study on Complex Formation of Tungsten (VI) with Glycine Cresol Red
Authors: Srivastava K. C. , Rao P. Appa 
Published: June 2015

AbstractGlycine cresol red (G. C. R) has been used as a complexometric indicator and a reagent for the spectrophotometric determination of inorganic ions1‐4. It forms stable coloured chelates iusolution with some metal ions under appropriate conditions. This communication give the composition and stability of tungsten G. C. R. Chelate.
Nuclear Magnetic Resonance Studies. IV. Proton Chemical Shifts and Coupling Constants of 2‐Norbornanols and Methyl‐Substituted 2‐Norbornanols
Authors: Liu Kwang‐Ting 
Published: June 2015

AbstractThe proton magnetic resonance spectra of the two isomeric 2‐norbornanols (I and II) and of eighteen of their methyl‐substituted derivatives (III to XX) under the influence of tris(dipivalomethanato)europium, Eu(dpm)3, have been measured. In all cases linear relationships between the observed shifts and the molar ratios of Eu(dpm)3 to substrate were realized. The chemical shifts obtained from the extrapolation to zero concentration of Eu(dpm)3 are in good agreement with the observed values. The coupling constants were found to be essentially unaffected by Eu(dpm)3. Consequently, determination of a chemical shift by extrapolation or of a coupling constant from the shifted spectrum appears to be justified. Reassignments of a number of signals are discussed. Chemical shifts, normalized induced shifts, and coupling constants are tabulated.
Synthesis and Characterization of Copper(II) and Nickel(II) Complexes of 1, 2–Cyclohexanediaminedipropanamide
Authors: Ojima Heijiro , Nonoyama Kiyoko 
Published: June 2015

AbstractComplexes of cupric ion and nickel ion with 1, 2‐cyclohexanediaminedipropan‐amide, prepared from cis‐l, 2‐cyclohexanediamine and acrylamide, are isolated from different acidities. Two isomeric forms for each are identified by physical means. The transition between them is observed in aqueous solution.
Studies on the Preparation and Properties of Thiol Derivatives of Biscyclopentadienyl Molybdenum (VI) and Bisindenyl Molybdenum (VI) Oxide Dichloride
Authors: Bhalla M. S. , Multani R. K. 
Published: June 2015

AbstractBiscyclopentadienyl molybdenum (VI) oxide dichloride (I) and bisindenyl molybdenum (VI) oxide dichloride (II) react with various thiols in tetrahydrofuran and from the complexes of the type (C3H5)2MoO (R2) and (C9H7)2MoO (R2) wherein R may be S CH8, S C2H5, S C3HN7, S C3H7, S C4Hn9, or S C4H3 or S C3H11. The preparation, thermal stabilities, physical characteristics and infrared spectra of these complexes have been studied in this paper.
Complexes of Ruthenium and Osmium with 4‐Amino‐2‐Mercapto‐5‐Nitroso‐6‐Pyrimidinol
Authors: Kushwaha V. , Jain P. , Katyal M. , Singh R. P. 
Published: June 2015

AbstractRuthenium(III) and osmium(VIII) form coloured complexes with 4–amino −2‐mercapto‐5‐nitroso‐6‐pyrimidinol (ammonium salt). The complexes have been spectrophotometrically studied and made use of in determination of the two metals; the reaction with ruthenium is particularly sensitive (0.006 μg of ruthenium/cm2for 0.001 absorbance). Many ions do not interfere in the determination.
Spectrophotometry Determination of Iron(III) and Cobalt(II) with Salicylaldehyde Hydrazone (SH)
Authors: Ray S. H. L. , Garg B. S. , Singh R. P. 
Published: June 2015

AbstractIron and cobalt complexation with salicylaldehyde hydrazone (SH) has been studied spectrophotometrically employing solvent extraction technique. The Fe(III)‐SH (1:3) and Co‐SH (1:2) complex absorb at 510nm and 450 nm respectively. The sensitivity of the colour reactions are 0.014 and 0.005 in terms of Sandell's definition for iron and cobalt systems. Both the complexes show maximum and constant absorbance in the pH ranges 3.5 to 5.0 and 6.2 to 7.0 for Fe(III)‐SH and Co(II)‐SH respectively. The complexation has been used in the spectrophotometric determination of iron and cobalt in coexistence with several ions.
Spectroscopic Studies on the Simple Rcooh System
Authors: Kuo Ching‐Hui , Chen Tunli 
Published: June 2015

AbstractThe carbonyl stretching vibration of monocarboxylic acid in CCl4 solution has been investigated. We introduce a new “m‐factor” to study the polymerization of this simple RCOOH system. The value of “m‐factor” was evaluated and tested in different concentrations and temperatures. Three classes of acid polymers were found as followings: linear dimer in class I (m≃2); linear and cyclic dimers in class II (m≃4); linear, cyclic dimers, and linear trimer in class III (m≃8). A linear relationship between log K1 and (ϵ−1)/(2ϵ+1) was found.
A Study on the Competitive Permeability of Anions in Anion Exchange Membrane
Authors: Huang Ting‐Chia , Shih Jun‐Whie 
Published: June 2015

AbstractThe selective permeability of two species of critical ions coexisting in Solution 1 for a third species of ions of the same charge in Solution 2 penetrate through the anion exchange membrane has been studied. The competitive permeability of coexisting ions depends on various concentrations, compositions and reaction time with the restriction that the volume of solution in each compartment is finite. The species which is easy to exchange across the membrane in multi‐ionic system has a high selective permeability at small composition and high total concentration condition. The experimental result shows that there exist overshooting and depletion effects for the fast ion when the reaction time is long enough, and the higher the permselectivity TCLOH is, the more appreciable the overshooting effect is. An explanation of the overshooting and depletion effects with finite volume of solution has been made specifically in discussion.
Phytochemical Study on Moghania Strobilifera
Authors: Chen Arh‐Hwang , Lin Shinn‐Ren , Hong Ching‐Jyi 
Published: June 2015

Abstractn‐C26H54, n‐C27H56, n‐C28H58, n‐C29H60, n‐C30H62, n‐C31H64, n‐C32H66, n‐C33H68, stigmasterol, β‐sitosterol and two unidentified compounds: a saturated ester (mp 79‐81°C); an unsaturated alcohol (mp 87‐88°C) were isolated from the whole herb of Moghania strotilifera.
Synthesis of a New Flavanoylchalcone
Authors: Chen Fa‐Ching , Ueng Tsong , Ho Tong‐Ing , Lin Yuh‐Meei 
Published: June 2015

AbstractAcidic cyclization of 3′, 3″′‐linked 2′, 2″′‐dihydroxy‐4, 4′, 4″, 4″′, 6′, 6″′‐hexamethoxybichalcone (I) with alcoholic phosphoric acid gave a new naringenyl‐chalcon hexamethyl ether (II) along with hexa‐O‐methyl‐8,8″‐binaringenin.
NMR Studies of Internal Rotation about the C‐C Bond in 1, 1, 2‐Trisubstituted Ethanes of the type XCH2‐CHX2
Authors: Lin Wei‐Chuwan , Chen Jenn‐Shing , Chen Li‐Shu , Lin Shin 
Published: June 2015

AbstractThe vicinal H‐H coupling constant in the AB2 spectrum, JAB, of 1, 1, 2‐trisubstituted ethanes of the type XCH2‐CHX2 has been measured in the medium of various solvents and at several different temperatures over the range of 238°‐368°K. Based on rotational averaging and on the simple model of internal rotation about the C‐C bond, a refiend Karplus equation for the vicinal coupling constant could yield the analytical expression which describes an explicit functional dependence of the vicinal coupling constant on internal rotation parameters, and permits evaluation of ΔE, the energy difference between rotamers, at any fixed temperature.For neat 1, 1, 2‐trichloroethane ΔE was found to keep constant over the range of temperature variation studied, while in the case of neat 1, 1, 2‐tribromoethane ΔE increases with increasing temperature in the same temperature range.In contrast to a small temperature effect a much pronounced medium effect on ΔE was observed for both 1, 1, 2‐tribromoethane and 1, 1, 2‐trichloroethane. At any fixed temperature ΔE decreases as dielectric constant of the solvent increases.
Thermodynamic Studies on the Complexation Reactions of copper(II) Macrocyclic Tetramine Complexes with Monodentate Ligands: I. RAC‐5, 7, 7, 12, 14, 14‐Hexamethyl‐l, 4, 8, 11‐Tetraazacyclotetradecane‐Copper(II) (Blue) with‐Halide Ions
Authors: Chung Chung‐Sun , Huang Shih‐Tsorng 
Published: June 2015

AbstractThe possibility of a trigonal bipyramidal structure for [Cu(tet b)X]+ (blue) (where X=Cl, Br, I) is supported by the observation of two distinct d‐d bands, which are assigned as and d, dxy→d and dxz, dyz→d transitions respectively. The stability constants for the formation of [Cu(tet b)X]+ (blue) from [Cu(tet b)]z+ (blue) and X− were determined by spectrophotometric method at 25°, 35° and 45°C. The corresponding δH° and δS° values were obtained from the variations of the stability constants between 25° and 45°C
The Structure of Cadinane‐4α, 9α‐Diol‐2‐Ene
Authors: Kuo Y. H. , Hsieh S. H. , Kao S. T. , Lin Y. T. 
Published: June 2015

AbstractThe structure of cadinane‐4α, 9α‐diol‐2‐ene, a crystalline compound from acetone extractive of Taiwania cryptomedioides Hayata, was established by chemical behavior and spectrospcopic data.
Polarographic Behaviour and Determination of Stability Constants of Uranyl‐Ascorbate Complex
Authors: Chyan Jiann‐Song , Lai Tsai‐Teh 
Published: June 2015

AbstractThe complex species of UO2(HA)(H2A)+ and UO2(HA)2 were identified in the ascorbic acid solution of uranyl ion at pH<2.1 and pH>2.1, respectively. Polarographic wave was proved to be the simultaneous reduction of UO2+2 and UO2(HA)(H2A)+ at pH <2.1. However, at pH>2.1, the wave is due to the reduction of U02(HA)2 The stability constants of the two complex species were found to be 5.1×10+ and 1.0×105, respectively. The hydrolysis constant of uranyl ion in the solution of ascorbic acid was determined.
The Emission in the Acetone Photochemical System
Authors: Tong Shen‐Nan , Ho Shih‐Yeng 
Published: June 2015

AbstractThe emission in the acetone photochemical system has been measured as a function of irradiating time and pressure. The emission yield generally increases with increase in irradiating time at both 3130 and 2654A. The increase of emission yields is due to the sensitized phosphorescence of the product biacetyl. The higher emission yield and lower biacetyl quantum yields at 3130A than that at 2654A support for that most of the excited acetone molecules are in the triplet state at 3130A.
A Spectrophotometric Study of the Chelate of Iron (III) with Sorbohydroxamic Acid and Its Analytical Application
Authors: Liu Chuen‐Ying , Sun Peng‐Jouxg 
Published: June 2015

AbstractIron (III) chelates of sorbohydroxamic acid have been studied spectrophotometrically in aqueous solution. Formation of sorbohydroxamic acid chelates was pH dependent. The “normalized absorbance” concept proposed by Likussar and Boltz has been utilized in the continuous variation plot method of determining the composition of metal chelates and the formation constants. The mole ratio of sorbohydroxamic acid to ferric ion was found to be 1 to 1 stoichiometry at pH lower than 2. The formation constant of this chelate has been evaluated to be 6.0×1011 at a constant ionic strength of 0.1 M at 30°C A spectrophotometric determination of ferric ion with sorbohydroxamic acid was proposed in conjunction with the present work.
Complex Formation of Ytterbium (III) with Bromopyrogallol Red—A Spectrophotometric Study
Authors: Srivastava K. C. 
Published: June 2015

AbstractThe complex formation of Ytterbium (III) with Bromopyrogallol red has been studied. spectrophotometrically in an attempt to establish composition, stability, thermodynamic parameters and optimum conditions for determining small amounts of ytterbium. The violet complex of ytterbium has λmax at 620nm against a reagent blank. The composition determined by different methods is 1:1 at pH 6.2±0.1. The mean value of log K, free energy (ΔG), the heat content (ΔH) and entropy (ΔS) changes, of the complex are found to be 6.0, —8.1.kcal/mole, —3.5 Kcal/mole and 15.53 e.U. respectively at 30°C. The net molar absorptivity and Sandell's sensitivity is 19850 and 0.0087 μg of ytterbium /cm2. The effect of diverse ions was examined with thirteen cations and ten anions in the determination of ytterbium.
Studies on the Alkaloids of Formosan Lauraceous Plants XIX Alkaloids of lindera oldhamii hemsl. (2)
Authors: Chen Ih‐Sheng 
Published: June 2015

AbstractOn the further investigation, N‐nordicentrine(V) and L,‐(+)‐magnocurarine(VII) have been isolated from the trunks and leaves of Lindera oldhamii Hemsl, respectively.
PMR Study of Molecular Complex Equilibrium in Solution 4‐Substituted Nitrobenzenes with Aromatic Donors
Authors: Lin Shin , Lin Wel‐Chuwan 
Published: June 2015

Abstract4‐Substituted nitrobenzenes, 4‐X‐C6H4NO2 (where X=‐Cl, ‐Br, ‐COCH2, ‐CHO), complexed with methyl benzenes in inert solvent cyclohexane have been studied by PMR spectroscopy. Equilibrium constant and the chemical shift of pure complex were determind through observation of the A2B2 spectrum of ring protons in the electron acceptor compounds. Equilibrium constant and chemical shift of pure complex were evaluated separately on the basis of either chemical shift A or B. Unequal chemical shift of pure complex was obtained and used to discuss the geometry of complex.
Studies on the Synthesis of the Sydnone Derivatives and its Properties III. Synthesis of Bissydnone
Authors: Tien Hsien‐Ju , Yeh Mou‐Yung 
Published: June 2015

AbstractTwo new bissydnones; 3,3′‐diphenyl‐4,4′‐bissydnone (I) and di(3‐sydnonyl)‐biphenyl (II) have been synthesized by Ullmann Reaction and Palladium chloride condensation in yields of 10‐70%.
The Decarboxylation of Catechuric Acid in Cresols and Phenol
Authors: Haleem M. A. , Hakeem M. A. 
Published: June 2015

AbstractKinetic data are reported for the decarboxylation of catechuric acid in four hydroxy solvents in the temperature range 150‐180°, The parameters of the absolute reaction rate equation are calculated. The reaction is first order. The observations support the view that all the decompositions proceed through an intermediate complex mechanism.
Complexometric Determination of Trivalent Metal Ions Using 1,2‐Naphthoquinone‐4‐Sulphonic Acid‐2‐Thiosemicarbazone as Metallochromic Indicator
Authors: Kesavan S. , Garg B. S. , Singh R. P. 
Published: June 2015

Abstract1,2‐Naphthoquinone‐4‐sulphonic acid‐2‐thiosemicarbazone (NQTS‐4S) has been used as visual indicator in the complexometric determination of trivalent metal ions, aluminium, gallium, indium, bismuth and iron. Simultaneous determination of aluminium and iron and of aluminium and copper has also been carried out. The standard deviation and percentage errors have also been calculated.
Triterpenoids and Some Other Constituents from Spiraea Formosana
Authors: Chou Cheng‐Jen , Wang Ching‐Bore , Lin Lung‐Ching 
Published: June 2015

AbstractThe ethanol extract of the stems of Spiraea formosana has been shown to contain triterpenes: friedelin (II), glutinol (III). β‐amyrin (IV); 10‐nonacosanol (I) and a mixture of sitosterol and campesterol. They were identified by chemical reactions, spectral data and compared with authentic samples (except 10‐nonacosanol).
Study on the Silylation of Aromatic Hydrocarbons. The Trimethylsilylation of Naphthalene
Authors: Yang Mei‐Hui , Liu Moon‐Lan , Liu Sheng‐Lieh 
Published: June 2015

AbstractDirect trimethylsilylation of naphthalene under certain condition has been found to afford substitution as well as addition products: 1‐and 2‐trimethylsilylnaphtalene (I, II), 1‐trimethylsilyl‐1,4‐dihydronaphthalene (III), trans‐1,2‐bis(trimethylsilyl)‐1,2‐dihydronaphthalene (IV‐a) and its isomer (IV‐b), and 1,2,4‐tris(trimethylsilyl)‐1,2‐dihydronaphthalene (V). The configuration has been determined by nmr spectroscopy, and the possible reaction path was proposed.
Synthesis of N‐(Homocyclylcarbamoyl)‐Maleamic Acids and ‐Maleimides
Authors: Liu Kang‐Chien , Shih Ching‐Yun 
Published: June 2015

AbstractA series of N‐homocyclylcarbamoyl derivatives of maleamic acid and maleimide was prepared for hypocholesteremic and sulfhydryl‐binding tests. The synthetic reactions involved in the controlled aminolysis of maleic anhydride with appropriate mono‐substituted ureas and the resulting carbamoylmaleamic acids were then thermally dehydrated to the corresponding carbamoylmaleimides. The monosubstituted ureas required in this synthesis were obtained by the action of amines on isocyanic acid produced in situ from nitrourea on heating in aqueous alcoholic solution.
Salicylate of Uranium
Authors: Dubey S. , Hasan M. , Kapoor R. N. 
Published: June 2015

AbstractThe reactions of uranium pentaethoxide with salicylic acid have been carried out in different stoichiometric ratios, yielding products of the type, U(OEt)3(C7H4O3), U(OEt)(C7H4O3)2, U(C7H4O2)2(C7H4O3), and U2(C7H4O3)3. A detailed study of the complexation reactions of uranyl ion with salicylic acid have also been made by potentiomertic and conductometric methods. The formation of 1:1 and 1:2 complexes have been confirmed by preparative studies. Two compounds, viz. (C5H6N)2UO2(C7H4O3)2 (NH4)2UO2(C7H4O3)2 have been isolated.
Determination of Trace Iron(II) in the Presence of Iron(III)
Authors: Luo Chien‐Shu , Hwang Jon‐Mau , Pung Tong‐Chuin , Tsai Hui‐Tuh 
Published: June 2015

AbstractThe determination of trace iron(II) is usually interfered by the presence of iron(III) when ortho‐phenanthroline colorimetric method is used. In this report a chromogenic reagent which contains ortho‐phenanthroline‐EDTA mixture has been developed to decrease the interference of ferric ion after adjusting the acidity of sample at 0.1 N by adding the sulfuric acid.The procedure is also simplified by introducing sulfamate buffer solution (pH= 1.5) without adjusting the acidity of sample with sulfuric acid. If iron(III) is not present in the sample, this method is also applicable. The comparative results are exhibited for the present method and the conventional o‐phenanthroline method.
Electrochemistry in Organic Synthesis.: I. Large‐Scale Preparation of Cysteine From Cystine
Authors: Wong Chi‐Huey , Wang Kung‐Tsung 
Published: June 2015

AbstractCysteine hydrochloride was prepared by electroreduction of cystine with stainless steel plate as electrodes. 0.25 M of cystine in 1.5 N HC1 as cathode solution was divided by anion‐exchange membrane from anode solution (1.5 N HC1). A current of 5.6 A/S was applied and at the end of reaction, crysteine hydrochloride was obtained by evaporation of the cathode solution. The method is more convenient than the existing method.
A New Numerical Method for Automated Spectral Isolation of Component Substances in a Set of Mixtures
Authors: Lin Chi‐Hsiung , Liu Shi‐Chung 
Published: June 2015

AbstractA new numerical method for isolating component spectra from spectra of their mixtures is presented. The method searches the component spectra by optimizing a risk function which assigns a relative value for the risk to regard a spectral shape as that of a pure substance. No prior knowledge of the nature of existing components is required in the analysis. All components conceivable in the set of mixture spectra are simultaneously isolated.
Reactions of Oligomeric Difluorosilylenes with Cis ‐and Trans‐Difluoroethylene
Authors: Liu Chao‐Shiuan , Hwang Tsai‐Lih 
Published: June 2015

AbstractThe reactions of oligomeric difluorosilylenes with cis ‐and trans ‐difluoroethylene are studied. All six new products are characterized and the stereochemistry suggests an integrated reaction mechanism in which both addition and insertion pathways share a common diradical transition state.
Enzymatic Synthesis of Oligopeptide. Part I. Papain‐Catalyzed Synthesis of Dipeptide, Tripeptide and Tetrapeptide
Authors: Chou Shan‐Ho , Chen Shui‐Tien , Wong Chi‐Huey , Wang Kung‐Tsung 
Published: June 2015

AbstractEighteen Z‐X‐Y‐OTNB+ type dipeptides, four Z‐Val‐Cys(Bzl)‐X‐OTMB tripeptides and a tetrapeptide Z‐Val‐Cys(Bzl)‐Cys(Bzl)‐Asn‐OTMB have been synthesized by papain‐catalyzed reaction in reasonable yield after recystallization. Z‐DL‐Ala‐OH has been resolved through papain‐catalyzed synthesis of Z‐L‐Ala‐Leu‐OTMB with an optical purity as high as 98.6%. These results show that papain is a good catalyst for oligopeptide synthesis.