bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zone-Melting Separation of Carbazole and Anthracene from Polynuclear Aromatic Compounds Using Biphenyl as a Medium, Followed by the Synchronous Fluorometric Determination
Authors: Tachibana Masaki , Furusawa Motohisa 
Published: July 2006

Abstract
Biphenyl is favorable as a zone-melting medium for the selective separation of small amounts of carbazole and anthracene and a subsequent determination. A definite amount (20–100 mg) of an aromatic sample was mixed with 4 g of purified biphenyl. The mixture was zone-melted 20 times. The two analytes were accumulated in the beginning part of the zone-molten ingot, but many others were eliminated from the part. After being dissolved in xylene along with the biphenyl, carbazole and anthracene could be simultaneously determined up to 10 ng ml−1 by measuring the synchronous fluorescence intensities at 340 and 384 nm, respectively.
Spectroscopic and Electrochemical Characterization of 18-Molybdodisulfate(VI)(4−), S2Mo18O624−
Authors: Himeno Sadayuki , Hori Toshitaka , Saito Atsuyoshi 
Published: July 2006

Abstract
The formation conditions of a yellow Dawson-type S2Mo18O624− anion have been investigated as functions of the concentrations of Mo(VI), H2SO4, organic solvents, the nature of the organic solvents used, temperature of the solution, and the reaction time. For a 50 mM Mo(VI)/50% (v/v) acetonitrile system, the yellow S2Mo18O624− anion formed in 0.2–1.0 M H2SO4, while a pale-yellow Mo6O192− anion did in 0.04–0.3 M H2SO4. The yellow heteropolyanion is electrochemically reduced in six successive steps to mixed-valence heteropoly blues at the glassy carbon electrode. Each of the first four waves corresponds to a reversible two-electron transfer. The mixed-valence blue species were characterized by their inherent visible and infrared (IR) spectra.
35Cl NQR in SnCl4·2Me2O and SnCl4·2Et2O
Authors: Mishima Mitsuo , Okuda Tsutomu 
Published: July 2006

Abstract
35Cl NQR spectra in SnCl4·2Me2O and SnCl4·2Et2O have been observed. Three crystal modifications of SnCl4·2Me2O have been found. A cis geometry is suggested for one of them, and a trans geometry for the remainder. A transformation between the cis and trans isomers in the solid state is indicated. The Zeeman effect on single crystals of cis-SnCl4·2Me2O and SnCl4·2Et2O has provided detailed information on bond angles and bond character. It is confirmed that the molecular geometry of cis-SnCl4·2Me2O belongs to the C2 group and that SnCl4·2Et2O has a trans geometry. The η values of the Cl atoms in cis-SnCl4·2Me2O are negligibly small and those of the Cl atoms in SnCl4·2Et2O are 0.11. The relatively small η values for the latter are ascribed to π bonding between the Sn and Cl atoms.
Preparation, Crystal Structure, and Solid State Properties of Highly Conductive (Phthalocyaninato)platinum Radical Salts: PtPc(ClO4)0.5 and PtPc(AsF6)x
Authors: Yamakado Hideo , Yakushi Kyuya , Kosugi Nobuhiro , Kuroda Haruo , Kawamoto Atsushi , Tanaka Jiro , Sugano Tadashi , Kinoshita Minoru , Hino Shojun 
Published: July 2006

Abstract
New conducting salts of (phthalocyaninato)platinum (PtPc), PtPc(ClO4)0.5 and PtPc(AsF6)x, were prepared by electrochemical oxidation. A crystal of PtPc(ClO4)0.5 belongs to a tetragonal system with a space group of P4⁄mcc, the lattice constants being a=14.062(1) Å, c=6.510(1) Å, and Z=2. They are metallic at least down to 120 K, the room-temperature conductivity being σ=102–103 S cm−1. XPS indicates that the conduction pathway is located mainly at the ligand chain due to a partial oxidation of the ligand-centered HOMO. ESR experiments have also strongly supported this conclusion. The bandwidth of the ligand-centered conduction band has been estimated to be 1.2 eV from the plasma frequency, hωp=0.87 eV, which is obtained by the polarized reflectance spectrum.
Magnetic and Electric Properties of a Cation Radical Salt Tris(decacyclene) Bis(hexafluorophosphate), (Dc)3(PF6)2
Authors: Sugano Tadashi , Kinoshita Minoru 
Published: July 2006

Abstract
A cation radical salt between a π-electron donor decacyclene and hexafluorophosphate, (Dc)3(PF6)2, was prepared by electrochemical synthesis, and conductivity (90–350 K), electron paramagnetic resonance (4–400 K) and static susceptibility (2–300 K) were measured. The salt was found to be semiconductive with the conductivity of ca. 4×10−2 S cm−1 at room tempertature and the activation energy of 66±3 meV. The magnetic measurements show that this salt is paramagnetic and spin susceptibility is thermally activated with the activation energy of 17 meV resulting from antiferromagnetic intermolecular interaction, although the dication of electron donor might be expected to have triplet spin multiplicity to stabilize ferromagnetic spin alignment in the ground state. The magnetism of (Dc)3(PF6)2 is discussed in terms of charge-transfer interaction among donors.
Stereoselective Synthesis of 2,4-Diamino Acids by Asymmetric Hydrogenation
Authors: Park Nam Gyu , Lee Sannamu , Maeda Hiroshi , Aoyagi Haruhiko , Kato Tetsuo 
Published: July 2006

Abstract
A stereoselective synthesis of unusual basic amino acids, ornithine, 2,4-diaminopentanoic acid, and 2,4-diamino-6-methylheptanoic acid, was achieved by the hydrogenation of cyclic α,β-dehydro dipeptides obtained by the condensation of cyclo(–Gly–l(or d)-aminoacyl–) and protected linear or chiral amino aldehydes. The degree of chiral induction greatly depended on the bulkiness of the side chains of α,β-dehydro amino acids. The Rf values on paper chromatography of (2S,4S or 2R,4S)-diaminopentanoic acid prepared by the present method were different from the reported values of a compound which had been obtained from metabolic products of Clostridium sticklandii and estimated to be 2,4-diaminopentanoic acid.
Synthesis and Reaction of 2,2′-Biquinolyl
Authors: Wakabayashi Shoji , Kubo Yukihiro , Takeda Takashi , Uenishi Jun-ichi , Oae Shigeru 
Published: July 2006

Abstract
A title compound is readily prepared from methyl 2-quinolyl sulfoxide (3) with methylmagnesium bromide in excellent yield and an ipso addition of alkylmagnesium halides to 2,2′-biquinolyl (4) is also described.
Effective Doping of Polymer Anion during Chemical Polymerization of Pyrrole Using Fe(OH)3 Oxidant
Authors: Ohtani Akira , Shimidzu Takeo 
Published: July 2006

Abstract
Polypyrroles were prepared by the chemical polymerization of pyrrole using various combinations of Fe3+ oxidants and electrolytes. The morphology and yield of the resulting polymers were affected by the property of the electrolyte anion in the oxidative solution. The size of the particles of the resulting polymers was decreased by using a high-molecular-weight polymer anion as the electrolyte anion. Both the polymer anion and Cl− were incorporated as a dopant into the polypyrrole matrix during the chemical polymerization of pyrrole, using an aqueous solution containing both FeCl3 and the polymer anion. On the contrary, the polymer anion was effectively incorporated as a dopant into the polypyrrole matrix during the chemical polymerization of pyrrole, using an aqueous solution containing both Fe(OH)3 and the polymer acid. A novel type of chemical preparation of the polypyrrole-polymer anion composite using the Fe(OH)3 oxidant and the polymer acid was developed.
The Crystal and Molecular Structures of Bis[1,2-bis(methylthio)vinylenedithio]-tetrathiafulvalene (TMTVT)
Authors: Nakano Hideyuki , Nogami Takashi , Shirota Yasuhiko , Harada Shigeharu , Kasai Nobutami 
Published: July 2006

Abstract
An X-ray crystal structure analysis of the title molecule (TMTVT) was made. The central portion of tetrathio-TTF was shown to be almost planar, and the outer portions of the two bis(methylthio)vinylenes are bent toward opposite directions each other. TMTVT molecules form a columnar stack toward the c-axis with equal intermolecular spacings.
Highly Stereoselective Palladium(0)-Catalyzed Allylation of Active Methylene Compounds with Allyl Imidates under Neutral Conditions
Authors: Suzuki Osamu , Inoue Seiichi , Sato Kikumasa 
Published: July 2006

Abstract
In the presence of a catalytic amount of Pd(0), active methylene compounds were allylated by allyl imidates under neutral conditions. In allylation with 3,3-disubstituted allyl imidates, e.g., geranyl and neryl imidate the effect of solvent and ligand to the E/Z ratio are investigated. The reaction in dimethyl sulfoxide by addition of diphosphine, e.g., 1,2-bis(diphenylphosphino)ethane, or large excess of triphenylphosphine as additive ligand gave best results. In these conditions, various active methylene compounds were allylated stereoselectively, especially complete retention of starting olefin geometry was achieved with neryl imidate.
On the Reaction of N-Vinyliminophosphoranes with 2,4,6-Cyclooctatrienone. Intermediate Formation of 8-Azabicyclo[5.3.1]undeca-2,4,7,9-tetraene Ring System
Authors: Nitta Makoto , Kanomata Nobuhiro 
Published: July 2006

Abstract
The reaction of N-(1-phenylvinyl)iminotriphenylphosphorane and of N-(1,3,5-cycloheptatrienyl)iminotributylphosphorane with 2,4,6-cyclooctatrienone gave an intermediacy of 8-azabicyclo[5.3.1]undeca-2,4,7,9-tetraene derivatives, which underwent an intramolecular Diels–Alder reaction to construct a tetracyclic ring system.
Synthesis of Novel 10-Se-3 Type Selenatetraazapentalene Derivatives with a Hypervalent Selenium
Authors: Matsumura Noboru , Tomura Masaaki , Yoneda Shigeo 
Published: July 2006

Abstract
Novel selenatetraazapentalene derivatives, 2,3-disubstituted 6,7-dihydro-5H-2a-selena(2a-SeIV)-2,3,4a,7a-tetraazacyclopent[cd]indene-1,4(2H,3H)-dithione, were synthesized by a convenient one-pot reaction using the lithium selenoureide/phenacyl chloride/alkyl isothiocyanate system in good yields.
Reactions of Tetrasulfur Tetranitride with Tropolone and Its Several Halogeno Derivatives. Preparations of 4H-Cyclohepta[c][1,2,5]thiadiazol-4-ones, 6H-Cyclohepta[c][1,2,5]thiadiazol-6-one, and 7H-Cyclohepta-[1,2-c:3,4-c′]bis[1,2,5]thiadiazol-7-ones
Authors: Mori Akira , Nakashima Hisataka , Mataka Shuntaro , Tashiro Masashi , Takeshita Hitoshi 
Published: July 2006

Abstract
The reactions of tropolones with tetrasulfur tetranitride gave 4H-cyclohepta[c][1,2,5]thiadiazol-4-ones, 6H-cyclohepta[c][1,2,5]thiadiazol-6-one, and 7H-cyclohepta[1,2-c: 3,4-c′]bis[1,2,5]thiadiazol-7-ones (9–56% yields) in one step. The yields of the products were not improved so much under high pressure and by the addition of a radical initiator.
Electroorganic Synthesis Using Organometals. 2. Reductive Dehalogenation of Halides with Carbonylferrates Derived from Pentacarbonyliron(0) and Cathodically-Generated Methoxide Ion
Authors: Hashiba Shigeto , Fuchigami Toshio , Nonaka Tsutomu 
Published: July 2006

Abstract
A stoichiometry for the reductive dehalogenation of an organic halide with carbonylferrates was established: One mol of the halide was quantitatively reduced with the carbonylferrates derived from 0.2 mol of pentacarbonyliron(0) and 2 mol of cathodically-generated tetramethylammonium methoxide. The dehalogenation was also examined using a variety of halides under the stoichiometric reaction conditions.
Synthesis of 2-Methylsulfonylmethyl-3,4,5-trimethoxybenzyl Methyl Ether. Confirmation of the Structure of Two Pyrogallols Isolated from Red Alga
Authors: Ohira Susumu , Shirane Fukue , Nozaki Hiroshi , Yahiro Shigeru , Nakayama Mitsuru 
Published: July 2006

Abstract
2-Methylsulfonylmethyl-3,4,5-trimethoxybenzyl methyl ether was synthesized in 4 steps from methyl 3,4,5-trimethoxybenzoate, confirming the structure of the natural phenol.
Solvent Effect on the Hydrogen Bonds between Guanine and Cytosine and between Hypoxanthine and Cytosine
Authors: Ohta Yoshihisa , Nishimoto Kichisuke , Tanaka Hidetsugu , Baba Yoshihiro , Kagemoto Akihiro 
Published: July 2006

Abstract
The solvent effect on the hydrogen bonds between guanine and cytosine and between hypoxanthine and cytosine was studied by means of solution calorimetry and ab initio MO calculations. The experimental enthalpy changes for guanine–cytosine and hypoxanthine–cytosine systems in aqueous solution were estimated to be about −10 and −14 kJ mol−1, respectively. In order to explain these experimental results, the electronic structures of hydrated bases and hydrated base pairs were calculated, assuming two types of hydration schemes. In the first type, it was expected that the complementary base pairs were destabilized in aqueous solution. In the second type, the stabilization energies in aqueous solution were calculated to be −11.9 kJ mol−1 for the hydrated guanine–cytosine system and −18.5 kJ mol−1 for hypoxanthine–cytosine one, respectively, which agreed with the experimental results. This suggests that water molecules bound to base pairs contribute to the stabilization/destabilization of hydrogen bonds between bases. The present calculation showed the possibility of C–Hδ+···O hydrogen-bond formation between the complementary base pair and H2O.
Studies on the Area–Temperature Isobars of Insoluble Monolayers at the Air/Water Interface. I. Development of a Microcomputer-Controlled Instrument for Measuring Precise Area–Temperature Isobars
Authors: Kato Teiji , Wakana Tatsushi , Ohshima Katsunori , Suzuki Katsuhiro 
Published: July 2006

Abstract
A microcomputer-controlled instrument for measuring precise area–temperature (A–T) isobars of insoluble monolayers at the air/water interface was developed. To obtain precise A–T isobars, leakage or dissolution of film material must be checked. Before starting A–T isobar measurements, area or structural relaxations must be completed. A–T isobars of monolayers of cadmium eicosanoate, l-α-dipalmitoyl phosphatidylcholine (DPPC), trioctadecanoyl glyceride (TOG), and cis-9-octadecen-1-ol were measured. Precise A–T isobars can afford two-dimensional isobaric thermal expansivities of insoluble monolayers by differentiation with respect to temperature. The thermal expansivities were evaluated as around 9.0×10−4 K−1 for condensed monolayers and around 30×10−4 K−1 for liquid-expanded monolayers.
Syntheses, and Crystal and Molecular Structures of Tetraethylammonium [Hexakis(isothiocyanato)lanthanoidates(III)] Including Aromatic Hydrocarbon or Halohydrocarbon: [(C2H5)4N]3[M(NCS)6]·G (M=Er, or Yb; G=Benzene, Fluorobenzene, Toluene, or Chlorobenzene)
Authors: Arai Hisanori , Suzuki Yasuo , Matsumura Naomi , Takeuchi Toshio , Ouchi Akira 
Published: July 2006

Abstract
The title new complexes were synthesized and their crystal and molecular structures were determined by the single-crystal X-ray diffraction method. The crystal form of [(C2H5)4N]3[Yb(NCS)6]·(C6H6), for example, is monoclinic, space group P21⁄c, a=19.458(12), b=14.046(6), c=18.288(7) Å, β=91.28(4)°, Z=4, and the final R value obtained was 0.064. The other seven crystals are isomorphous with each other. The central metal atom is in an octahedral hexa-coordination geometry: six nitrogen atoms of isothiocyanate ions are ligated to each metal atom. Each solvent molecule is arranged betweeen each pair of neighboring metal atoms along the [1 \bar1 0] axis in each crystal. The cations are arranged approximately between each pair of metal atoms along the [0 1 1], [0 \bar1 1], and [1 1 0] axes, respectively. They were stable for more than a few weeks at room temperature; however, when heated at about 80–90 °C, their guest molecules were lost.
Solvent Influence on the Circular Dichroism Spectrum of Potassium Ethylenediaminetetraacetatocobaltate(III)
Authors: Taura Toshiaki 
Published: July 2006

Abstract
The circular dichroism (CD) spectrum of optically active potassium ethylenediaminetetraacetatocobaltate(III), (+)-K[Co(edta)]·2H2O, was measured in water and a variety of organic solvents: ethylene glycol, methanol, formamide, ethanol, 2-propanol, chloroform, nitromethane, dichloromethane, dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, benzonitrile, N,N-dimethylacetamide, and acetone. The spectra in organic solvents were obtained for the solutions of the complex anion, which were prepared by the addition of a macrobicyclic polyether, cryptand 222. It was found that the peak positions and intensities of the CD bands are markedly influenced by the solvent molecules and this solvent influence on the peak position is linearly correlated to the influence on the corresponding first d–d absorption spectrum. Therefore, the solvent influence on the CD spectrum of this complex is suggested to be caused by the change in the d–d transition energy of this Co(III) complex anion. Furthermore, the positions and intensities of the CD peaks were also correlated with the electrophilic ability (the acceptor number: AN) and the bulk polarity (the dielectric constant) of the solvent, respectively. It is proposed that the inherent CD spectrum of [Co(edta)]− that is not solvated could be estimated on the basis of this correlation.
Mechanism of the Reaction of (Arylthio)trimethylgermanes with 1-Aryl-1-bromoethanes—Kinetic and Stereochemical Studies—
Authors: Kozuka Seizi , Nitta Takemi , Tamura Shoji , Tagaki Waichiro 
Published: July 2006

Abstract
Kinetic and stereochemical studies have been conducted on the reaction of (arylthio)trimethylgermanes with 1-aryl-1-bromoethanes. The reaction has been found to obey a first-order kinetic equation. The rates of the reaction of the substituted arylethanes were well-correlated with σ+ constants. Optically active 1-bromo-1-phenylethane gave racemic phenyl 1-phenylethyl sulfide by the reaction with trimethyl(phenylthio)germane. An SN1 ionization of 1-aryl-1-bromoethanes has been suggested as the reaction mechanism.
Studies of the Hydrous Niobium(V) Oxide Ion Exchanger. V. Effect of Heat Treatment on the Sodium Isotopic Exchange Rates between Hydrous Niobium(V) Oxide in Na+ Form and Aqueous Solutions
Authors: Inoue Yasushi , Yamazaki Hiromichi , Ikeda Mitsuji 
Published: July 2006

Abstract
The effect of a heat treatment was studied on the sodium isotopic exchange rate between the hydrous niobium(V) oxide in the Na+ form and aqueous solutions. The rate was controlled by the particle diffusion of sodium ions and increased with the heat-treatment temperature. The increase in the rate for the exchanger heat-treated at 200 °C was due to a decrease in the effective particle radius brought about by cracks which developed in the particles. A further increase in the rate at temperatures higher than 200 °C could be explained in terms of an increase in the Na+-diffusion coefficient, which was produced by an increase in the pore size responsinble for the movement of sodium ions.
The Mechanism of Seasonal Variation in the Size Distributions of Atmospheric Chloride and Nitrate Aerosol in Tokyo
Authors: Hara Hiroshi , Kato Tsuyoshi , Matsushita Hidetsuru 
Published: July 2006

Abstract
The volatility of ammonium chloride and nitrate was demonstrated to be responsible for the seasonal variation in size distributions that is the atmospheric fine-mode (&lt;2 μm) chloride and nitrate aerosol were predominant in winter, but the coarse mode (&gt;2 μm) was more pronounced in summer. An ion-balance examination and heating of winter aerosol samples demonstrated that fine-mode chloride and nitrate species are ammonium salts which are volatile at summer atmospheric temperatures. Both volatilized and unvolatilized concentrations of these chloride and nitrate species were determined both in winter and in summer to prove that the gas–solid interconversion took place in the atmosphere. The log-normal distributions of the ionic-component concentrations and the seasonal changes in the ionic composition of fine-mode aerosol were also discussed.
Electrochemical Behavior of Azoxybenzene-4,4′-disulfonamide at Pyrolytic Graphite Electrode
Authors: Goyal R N , Bhargava Sandhya 
Published: July 2006

Abstract
The electrochemical reduction of azoxybenzene-4,4′-disulfonamide has been studied in the Britton Robinson buffers of pH range 3.0–10.6 at a pyrolytic graphite electrode. The electroreduction was found to occur in a single well defined 4e, 4H+ peak. The hydrazo compound has been identified as the main product of the electrode reaction.
Solvent and Electrode Kinetic Effects on Cathodic Reduction of I3−+2e→3I− in Some Pure and Mixed Dipolar Aprotic Solvents
Authors: Bhattacharya Swapan , K. Kundu Kiron 
Published: July 2006

Abstract
Exchange current densities (i0) of the redox reaction I3−+2e−=3I− have been determined at 25 °C on platinum (Pt) and graphite (C) electrodes in acetonitrile (ACN), propylene carbonate (PC), N,N-dimethylformamide (DMF), and their binary mixtures by potentiostatic polarization studies under near equilibrium conditions. The studies in pure solvents have also been extended to 15 and 35 °C and also on platinized graphite (C)Pt electrode. The kinetic solvent effect data at 25 °C have been analyzed in the light of relative solvation of I2 and transition state (TS) as reflected from the previously reported transfer free energies (ΔGt°) of I2 and that of TS derived therein for the respective solvent systems. The electrocatalytic activities of (C)Pt electrode in different solvent systems are found to be of the same order as that of Pt electrode possibly because of its large roughness factor. But the observed energies of activation (Ea) being of the order C&gt;&gt;C(Pt) ≈Pt suggest that graphite is intrinsically a weaker electrocatalyst than both the (C)Pt and Pt electrodes, which are however equivalent to each other so far as electrocatalytic activity is concerned. Moreover, while the electrocatalytic activity of Pt and (C)Pt electrodes is found to be in the order ACN&gt;PC&gt;DMF, that of C is ACN&gt;DMF&gt;PC, which have been ascribed to result from the differential adsorption propensities of the solvent molecules with respect to Pt and C surfaces respectively.
Amorphous and Crystalline Peroxopolytungstic Acids Formed from Tungsten and Hydrogen Peroxide
Authors: Okamoto Hiroshi , Ishikawa Akira , Kudo Tetsuichi 
Published: July 2006

Abstract
Peroxopolytungstic acids, WO3·xH2O2·yH2O (0≤x≤1), formed directly from tungsten and hydrogen peroxide are found to be crystalline or amorphous depending on x.
Synthesis of Five-Membered Cyclic Ketones Using Potassium Tetracarbonylferrate(2—)
Authors: Yamashita Masakazu , Uchida Masaya , Tashika Haruyoshi , Suemitsu Rikisaku 
Published: July 2006

Abstract
Various five-membered cyclic ketones were prepared from 1,4-dihaloalkanes and potassium tetracarbonylferrate(2—) in moderate to high yields. However, the yields of six- or seven-membered cyclic ketones from the corresponding dihalides were rather low.
The Dehalogenation of vic-Dihaloalkanes to Alkenes with Sodium Trithiocarbonate or Sodium Dithiocarbonate in the Presence of Phase-Transfer Catalysts
Authors: Sugawara Akira , Nakamura Atsushi , Araki Akitoshi , Sato Ryu 
Published: July 2006

Abstract
The reductive dehalogenation of vic-dihaloalkanes with aqueous sodium trithiocarbonate or sodium dithiocarbonate in the presence of a phase-transfer catalyst gave the corresponding alkenes in high yields under mild conditions.
An Oxidative Dimerization of Anthrones by Oxygen-Metal Acetate System
Authors: Yamaguchi Masahiko , Hasebe Koichi , Uchida Minoru , Higashi Hirofumi , Minami Toru 
Published: July 2006

Abstract
Anthrones were oxidatively dimerized with oxygen in the presence of Pb(OAc)2 giving 9,9′-bianthracene-10,10′(9H,9′H)-diones. The dimerization proceeds under mild reaction conditions, and gives products in good yields. Binaphthacenedione and bipentacenedione were also synthesized.