bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Propagators in the Hückel Model. V. Polarizabilities
Authors: Aono Shigeyuki , Nishikawa Kiyoshi 
Published: July 2006

Abstract
The ordinary perturbation theory is reformulated in terms of propagators. It is well known that, if the perturbing interaction has a single particle character, the additional energy up to the second order of the perturbation is expressed by bond orders and various polarizabilities. This is easily rewritten by use of propagators. In addition, under the tight-binding approximation, the propagators of linear and ring polyenes are expressed in simple analytical forms, which enable us to give also analytical expressions for bond orders and polarizabilities. A simple application is given to determine which is more stable, anthracene or phenanthrene.
Optical Resolution of β-Hydroxynorvaline
Authors: Yamada Masaki , Okawa Kenji 
Published: July 2006

Abstract
β-Hydroxy-Dl-norvaline(HyNva) was successfully separated into its diastereoisorners by fractional crystallization from 2-propanol as p-toluenesulfonic acid(TsOH) salts. The two racemic diastereoisorners were resolved into four stereoisomers by Vogler’s method, using diastereomers of the N-benzyloxycarbonyl Dl-amino acid and l-tyrosine hydrazide.
Pressure and Temperature Effects on Conformational Equilibria between Rotational Isomers. II. Isobutyl and s-Butyl Halides in Hexane and Methanol
Authors: Nomura Hiroyasu , Koda Shinobu 
Published: July 2006

Abstract
The conformational changes in isobutyl halides (i-BuX) and s-butyl halides (s-BuX) in hexane and methanol have been analyzed by Raman spectroscopy as a function of temperature and pressure. The enthalpy and volume differences in the conformational changes from PC (trans) to PH (gauche) of i-BuX and from SHH(trans) to SHH′(gauche I) and to SCH(gauche II) of s-BuX in the dissolved state have been obtained. The enthalpy and volume differences, ΔH and ΔV, of all the conformational changes depended on the solvents and the concentration in solution. In the solution of hexane, the ΔH (PC→PH) of i-BuCl and i-BuBr both increased with a decrease in the concentration of i-BuX. The ΔV (PC→PH) of i-BuCl increased with an increase in the contents of the solvents, hexane, but that of i-BuBr decreased. The concentration dependences of ΔH and ΔV were discussed on the basis of the intermolecular interactions. The relation between ΔH and ΔV was also discussed on the basis of thermodynamic consideration.
Studies of the Hydrous Niobium(V) Oxide Ion Exchanger. II. Affinity for Various Cations
Authors: Inoue Yasushi , Yamazaki Hiromichi , Okada Kazushi , Morita Kazuhiko 
Published: July 2006

Abstract
In order to elucidate the fundamental properties of hydrous niobium(V) oxide as a cation exchanger, the stoichiometry of cation exchange and the selectivity for various cations were studied. As the reversibility and the equivalent exchange between the cations were confirmed, this material showed an ideal cation-exchange reaction. The affinity series for alkali metal ions and alkaline earth metal ions were Cs+&gt;&gt;K+&gt;&gt;Li+ and Ba2+&gt;&gt;Sr2+≥Ca2+&gt;Mg2+ respectively; the values decreased in the order of the increase in the hydra ted ionic radii of the cations. For transition metal ions, the distribution coefficients had a strong correlation with the first hydrolysis constants of the cations and/or the first stability constants of their acetato complexes. Based on this finding, the transition metal ions are considered to be adsorbed on the exchanger by a bond partially covalent in character, rather than by a pure ionic bond. The pH-dependency of the distribution coefficients of the cations was discussed in terms of the effects of the dissociation of the exchange sites on the overall ion-exchange equilibrium.
Syntheses and Crystal and Molecular Structure of [Hexaaquabis(2-naphthalenesulfonato)lanthanoid(III)] 2-Naphthalenesulfonate Trihydrate, [Ln(C10H7SO3)2(H2O)6] (C10H7SO3)·3H2O (Ln=Pr, Nd, Sm, Eu, Gd, Dy, Er, and Yb)
Authors: Ohki Yoshiyuki , Suzuki Yasuo , Nakamura Masao , Shimoi Mamoru , Ouchi Akira 
Published: July 2006

Abstract
Eight isomorphous 2-naphthalenesulfonato complexes of lanthanoids(III) (Pr, Nd, Sm, Eu, Gd, Dy, Er, and Yb) were synthesized, and the structures of five of them were determined by the single-crystal X-ray-diffraction method. They are monoclinic, with the space group of P21; the cell constants of the PrIII complex, for example, were a=18.228(8), b=7.498(4), c=14.177(9) Å, β=107.75(4)°, Z=2, and its final R value was 0.043. The unit-cell size of the complex decreases with the increase in the atomic number of the metal atom. The central metal atom is in a square-antiprism geometry and is octa-coordinated with two unidentate 2-naphthalenesulfonato ligands and six water–oxygen atoms. Nonligated oxygen atoms of the sulfonato ions form hydrogen-bonds with the coordinated and lattice water molecules to form a double-layered network along the ab-plane. All the naphthalene rings stand together to form hydrophobic sheets between the hydrogen-bonding networks.
Conductometric Study of Cobalt(II), Nickel(II), Copper(II), and Zinc(II) Perchlorates in Methanol–Ethylene Glycol Mixtures
Authors: Doe Hidekazu , Kitagawa Toyokichi 
Published: July 2006

Abstract
The ionic association constants of M(ClO4)2 (M=Co, Ni, Cu, Zn) were determined by conductometric measurements in methanol–ethylene glycol mixtures of 100, 80, 60, 40, 20, and 0 wt% methanol compositions at 5, 15, 25, 35, and 45 °C. The conductometric data were analyzed using a modified Fuoss and Edelson method. The association constant of an ion pair M2+ClO4−, K1A, was studied and thermodynamic functions, ΔH1A\ominus and ΔS1A\ominus, for that association were determined at 25 °C. Free-energy changes, ΔG1A\ominus (=–RTlnK1A), at 25 °C which slowly decreased with an increase in the ethylene glycol content in a solvent, are in good agreement with estimates from Fuoss’ theory regarding ionic association. Values of both ΔH1A\ominus and ΔS1A\ominus were positive in many systems: i.e., unfavorable enthalpy and favorable entropy changes, and those were obtained near to estimates from the Fuoss’ theory in pure methanol, 100 wt%. However, there have been a few systems with a negative ΔH1A\ominus (Co, Ni, and Zn at 40 and 20 wt%, and Co at 0 wt%), contrary to theoretical expectations. These results are discussed from the standpoint of a changing solvation between M2+ and MClO4+. In all the solvents, moreover, the ΔH1A\ominus and ΔS1A\ominus values have been in a sequence according to Co&lt;Ni&lt;Cu&gt;Zn. The results of limiting molar conductances, Λ0, are discussed regarding Walden products.
ESR Studies on Salicylaldehyde Schiff Base Complexes of Copper(II). I. Bis(N-cyclohexyl- and N-cycloheptyl-salicylideneaminato)copper(II) Complexes and Their Derivatives in Polycrystals
Authors: Takeuchi Akira , Yamada Shoichiro , Yokoi Hiroshi 
Published: July 2006

Abstract
Twelve of the title complexes including color isomers show powder ESR spectra of various line shapes. These complexes are a novel series of copper(II) complexes which have very weak intermolecular spin-exchange interactions in crystals. Brown complexes and most green complexes show monomer and dimer ESR spectra, respectively. It is demonstrated by ESR measurements that the above green complexes are transformed into the brown ones only by grinding those green crystals finely and forcefully with agate mortar and pestle.
Physicochemical Speciation of Trace Elements in River Water by Means of Ultrafiltration
Authors: Tanizaki Yoshiyuki , Yamazaki Masao , Nagatsuka Sumiko 
Published: July 2006

Abstract
Ultrafiltration and Millipore filtration techniques have been used in the speciation of trace elements in Tama River water. The size distribution was clarified for 32 elements by means of neutron-activation analysis in order to discuss their chemical or physical forms. Alkali and alkaline-earth elements were primarily found in the dissolved-size fraction (&lt;0.45 μm). Their dissolved species were mostly distributed in the smallest-molecular-weight fraction (&lt;MW 500), although the alkaline-earth elements were also recognized to a significant extent (20–30%) in the middle-molecular-weight fraction (MW 104–500). Transition elements were principally associated with the suspended-size fraction (&gt;0.45 μm) in the upper reaches of the river, but in the lower reaches they were chiefly fractionated as the dissolved species, with the exception of Sc and Fe. The dissolved V and Mn were distributed in the smallest-molecular-weight fraction, while the Co, Ni, and Zn were divided between two smaller-molecular-weight fractions (MW 104–500 and &lt;MW 500). Light rare-earth elements were mostly associated with suspended materials. Heavier rare-earth elements were, on the contrary, mainly found in the dissolved-size fraction, while their dissolved species were concentrated in the middle-molecular-weight fraction. The dissolved species for As, Se, Sb, and W were divided into two smaller-molecular-weight fractions, although As, Se, and W were predominantly found in the middle-molecular-weight fraction and Sb was mainly detected in the smallest-molecular-weight fraction. Aluminium and Ag were mainly associated with suspended materials. Furthermore, the dissolved Al was mostly distributed in the smallest-molecular-weight fraction, while the Ag was concentrated in the largest-molecular-weight fraction (&gt;MW 104).
Methods for Observing the Deformation of an Aqueous Paramagnetic Solution in a Magnetic Field
Authors: Yasuoka Takashi , Kidokoro Tadahiko , Mitsuzawa Shunmei 
Published: July 2006

Abstract
Two methods have been worked out for the observation of the deformation of a paramagnetic aqueous solution in a magnetic field. The deformation was observed on: (1) a layer of a solution covered with a water-immiscible organic liquid and (2) a drop of the solution suspended in the liquid.
Selective Synthesis of LPG from Synthesis Gas
Authors: Fujimoto Kaoru , Saima Hitoshi , Tominaga Hiro-o 
Published: July 2006

Abstract
C2–C4 paraffins were produced from synthesis gas with selectivities higher than 80% at 300 °C and 21 atm by utilizing hybrid catalysts composed of a methanol-synthesis catalyst and a Y-type zeolite. The diffusion of lower olefins within zeolite pores and their hydrogenation on a methanol-synthesis catalyst were found to be important factors in controlling selectivity.
Synthesis and Properties of the [n](2,5)Pyridinophane Ring System
Authors: Kobayashi Tomoshige , Nitta Makoto 
Published: July 2006

Abstract
The synthesis and properties of a series of [n](2,5)pyridinophane derivatives (13a–e) (n=10, 8, 7, and 6) are described. These compounds are prepared in low yields by the [Mo(CO)6]-induced cycloaddition reaction of 3-aryl-4,5-polymethylene-substituted isoxazoles (11a–e) with dimethyl acetylenedicarboxylate. The reaction pathways are suggested to involve the inclusion of the acetylenic ester across the C-4–C-5 bond of the N-complexed isoxazoles and the subsequent elimination of the oxygen atom from the resulting isoxazoline ring. The structures of 13a–e are established on the basis of the 1H-NMR, 13C-NMR, and UV spectra. A significant strain for the pyridine ring in 13a–e is reflected in the UV spectra. As the [n] decreases in 13–e, there is a red shift in the absorption spectra. This feature is in good accordance with that observed in a series of [n]paracyclophane ring systems.
Aryliminodimagnesium Reagents. IX. The Reaction with Benzophenones. The Mechanism of Coordination and Electron Transfer Processes Distinct from That of Grignard Reaction
Authors: Okubo Masao 
Published: July 2006

Abstract
In the reaction of aryliminodimagnesium reagents(ArN(MgBr)2, Ar=C6H5, p-MeC6H4, and p-MeOC6H4) with some p-substituted benzophenones, the arylaminyl radicals(ArNMgBr) derived from the reagents were detected by ESR in low concentrations and identified by computer simulation. From comparison of all the itemized facts characteristic of the reaction with those of Grignard reaction of the same substrates, the mechanisms of initial coordination and electron transfer of the two reactions were distinguished.
The Pyrolyses of 1,1,4,4,-Tetraphenyl-1,4-butanediol and 1,1,4,4-Tetraphenyl-2-butene-1,4-diol Derivatives. Decomposition Reactions to Form Olefins via the Elimination of Two Mole Equivalents of the Hydroxydiphenylmethyl Radical
Authors: Saito Katsuhiro , Horie Yoichi , Mukai Toshio , Toda Takashi 
Published: July 2006

Abstract
The pyrolysis of 1,1,2,4,4-pentaphenyl-1,4-butandiol, trans-1,2-bis(hydroxydiphenylmethyl)hexane, trans-1,2-bis(hydroxydiphenylmethyl)indan, and cis-endo- and trans-1,2-bis(hydroxydiphenylmethyl)bicyclo[2.2.1]heptane gave styrene, cyclohexene, indene, and norbornene respectively, accompanied by benzophenone and benzhydrol. The pyrolysis of trans-1,2-bis(hydroxydiphenylmethyl)spiro[2.6]nona-4,6,8-triene afforded indene via rearrangement to form trans-1,2-bis(hydroxydiphenylmethyl)indan. The pyrolysis of cis-1,1,4,4-tetrapheny 1-2-butene-1,4-diol afforded 2,2,5,5-tetraphenyl-2,5-dihydrofuran. On the other hand, trans-1,1,4,4-tetraphenyl-2-butene-1,4-diol afforded 1,2,4,4-tetraphenyl-3-buten-1-one. The mechanisms of these decomposition reactions are discussed.
Effects of Alkyl Chains of Thiacarbocyanine as the Sensitizer for the Photoreduction of Methylviologen in Micellar Phase
Authors: Nakagaki Masayuki , Komatsu Hiroaki , Handa Tetsurou 
Published: July 2006

Abstract
Photoinduced reduction of methylviologen (MV2+) by ethylenediaminetetraacetate was investigated with 3,3′-dialkylthiacarbocyanines as a sensitizer in the micellar solution of a nonionic surfactant, heptaethylene glycol monododecyl ether. The alkyl chains of the dyes were found to have considerable effects on the reaction rate. The fluorescence yield of a dye having two long alkyl chains, 3,3′-dioctadecylthiacarbocyanine (C18–18) in the micellar phase was larger than that of the dye having only one long alkyl chain, 3-methyl-3′-octadecylthiacarbocyanine (C1–18). This result was discussed in terms of the large effective volume associated with the intramolecular twisting motion in the excited state of C18–18. Also, from the fluorescence quenching experiments, it was found that MV2+ was of easier access to C18–18 than C1–18 in the micellar phase. Thus, the relatively higher stability of the excited state of C18–18 and the easier access of MV2+ to C18–18 were considered to be responsible for the faster reaction rate achieved by C18–18 than by C1–18 in the micellar solution.
Studies of the Hydrous Niobium(V) Oxide Ion Exchanger. III. The Effect of Heat Treatment
Authors: Inoue Yasushi , Yamazaki Hiromichi , Matsuda Yuzo 
Published: July 2006

Abstract
The effects of heat treatments in air have been studied regarding the properties of a hydrous niobium(V) oxide ion exchanger in H+ form. The exchanger lost 17 per cent of the initial ion-exchange capacity when it was heat-treated at 110 °C; thereafter the exchange capacity decreased progressively with temperature until 400 °C, at which point it retained about a half of the initial value. The exchanger began to crystallize into γ-phase at a temperature between 450 to 500 °C where the capacity disappeared. The γ-phase transformed to α-phase at a temperature above 800 °C. An examination of the uptake curves showed that less-acidic exchange sites were more resistant than more-acidic sites to heat treatment. The existence of three kinds of water in the exchanger (adherent, zeolitic, and bound) has been suggested on the basis of the ion-exchange capacity, the thermal-analysis curves, and water recovery brought about by humidifying.
Simultaneous Multielement Determination of Trace Metals in Seawater by Inductively Coupled Plasma Atomic Emission Spectrometry Using Chelating Resin Column Preconcentration
Authors: Chu Jia Cheng , Akagi Tasuku , Haraguchi Hiroki 
Published: July 2006

Abstract
Preconcentration of trace metals in seawater using a Chelex-100 resin column was investigated for simultaneous determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimum preconcentration conditions were examined in detail. With 100 ml of 1 M ammonium acetate buffer solution (1 M=1 mol dm−3), the matrix elements in seawater could be removed sufficiently without loss of analytes. The concentration factor of 200 times could be achieved by dissolving the dried HNO3 eluent of the column. The blanks of the method were negligibly small for most elements investigated. The detection limits were in the range of several ng/1 to 100 ng/1 for Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn. The present technique was applied to the determination of trace metals in coastal and ocean seawater.
X-Ray Diffraction, Raman, and NMR Studies on Tetrathiocyanato Complexes of Zinc(II), Cadmium(II), and Mercury(II) Ions in Aqueous Solution
Authors: Yamaguchi Toshio , Yamamoto Kiyoshi , Ohtaki Hitoshi 
Published: July 2006

Abstract
X-Ray scattering, Raman, and 13C- and 14N-NMR measurements were performed on aqueous solutions containing tetrathiocyanato complex ions of Zn(II), Cd(II), and Hg(II). The radial distribution functions revealed that four thiocyanate ions tetrahedrally coordinated to Zn(II) and to Hg(II) ions through the N and S atoms, respectively, while Cd(II) ion was bound to two sulfur and two nitrogen atoms within the coordinated four SCN− ions. The bond distances and bond angles are as follows: Zn–N 204 pm, Cd–N and Cd–S 225 and 265 pm, respectively, and Hg–S 254 pm, and Zn–N–C 145°, Cd–N–C and Cd–S–C 149° and 106°, respectively, and Hg–S–C 102°. The Raman bands of the C–S vibration within the tetrathiocyanato complexes of Zn(II), Cd(II), and Hg(II) ions in aqueous solutions appeared at 821 and 710 cm−1 for the Zn(II) and Hg(II) complexes, respectively, consistent with the values in the literature. The C–S stretching Raman bands of tetrathiocyanatocadmate(II) complex were resolved into two components at 779 and 732 cm−1. The C–S frequency shifted toward the higher frequency side than that (747 cm−1) of the free SCN− ion in the case of the binding of SCN− to metal ion via the N atom in the Zn(II) and Cd(II) cases, while the C–S bands influenced by the M–S bonding appeared on the lower frequency side in the Cd(II) and Hg(II) complexes. The 13C chemical shifts of the tetrathiocyanato complexes in aqueous solutions showed the downfield and upfield shifts for Zn(II) and Hg(II), respectively, and the intermediate for Cd(II). The nitrogen-14 resonance in [M(SCN)4]2− in aqueous solutions shifted upfield (−30.8 ppm) for Zn(II), downfield (30.3 ppm) for Hg(II), and in between for Cd(II) (−1.3 ppm). The trend of the 13C- and 14N-chemical shifts supported the different types of binding of ambient SCN− ion deduced from the X-ray and Raman measurements.
Ion-exclusion Chromatography of Weak Acids Using a Carbonic Acid Solution as Eluent
Authors: Itoh Hisaaki , Shinbori Yoshio 
Published: July 2006

Abstract
Ion-exclusion chromatographic separation of organic acids using a carbonic acid solution as eluent is presented. This permits conductivity detection of ionic species without a suppressor as a post-column reactor. It was found that the proposed method was applicable to the separation of organic acids having pKa over ca 3.5. This technique was applied to the determination of acetic acid in pharmaceuticals without tedious sample preparation.
Use of Alternating Current Impedance Method in Diagnosing Electrode Kinetics of [Fe(CN)6]4−⁄3− Complex Confined to Protonated Poly(4-vinylpyridine) Film on Graphite Surfaces
Authors: Ohsaka Takeo , Ushirogouchi Toru , Oyama Noboru 
Published: July 2006

Abstract
A “heterogeneous” electron-transfer process of [Fe(CN)6]4−⁄3− redox couple, which was confined electrostatically to the protonated poly(4-vinylpyridine) (PVP) film, at basal-plane pyrolytic graphite (BPG) electrode/ PVP film interfaces and a “homogeneous” charge-transport process within the PVP film were examined by alternating current (ac) impedance method. The obtained impedance loci were found to correspond to those expected for the electrochemical impedance expressed by “Randles’s equivalent circuit.” The relevant kinetic parameters (i.e., the standard rate constant, k° and the cathodic transfer coefficient, α) of the electrode reaction, the apparent diffusion coefficients, Dapp, for the “homogeneous” charge-transport within the film, the double-layer capacity, Cd1 and the solution resistance, Rsoln were determined at various concentrations of [Fe(CN)6]3− in PVP coatings. The obtained Dapp, k°, and α values were compared with those recently obtained by normal pulse voltammetry. In addition, an equivalent circuit model is given for the impedance obtained for the redox reaction on a BPG electrode coated with a protonated PVP confining [Fe(CN)6]4−⁄3− couple.
A Study of the Inter-elemental Effect in the Carbon-furnace Atomic-absorption Spectrometry of Selenium and Mercury in Biological Samples by the Palladium-addition Method
Authors: Liu Ping , Wei Lei , Matsumoto Kazuko , Fuwa Keiichiro 
Published: July 2006

Abstract
In the electrically-heated carbon-furnace atomic-absorption spectrometry of selenium and mercury, interelemental interference is present between the two elements. Mercury has no effect on selenium sensitivity in a simple inorganic selenium solution. When, however, the solution contains organic materials such as 0.5% albumin, the selenium sensitivity is decreased. The presence of mercury in addition to the organic material further decreases the sensitivity to about a half of that of a solution containing only selenium and albumin. The addition of 0.94 mmol dm−3 palladium ion completely removes the negative interferences due to organic materials and mercury. On the other hand, in mercury determination the presence of organic materials also decreases the mercury sensitivity. The addition of palladium, in contrast to selenium determination, enhances the mercury sensitivity about 50 times, independent of whether or not the solution contains organic materials.
Synthetic Studies of Pyridomycin. IV. Syntheses of Some Twelvemembered Ring Compounds Designed for Construction of Intact Ring System with Exocyclic (Z)-s-Butylidene Side Chain in Pyridomycin
Authors: Kinoshita Mitsuhiro , Mori Yasuharu 
Published: July 2006

Abstract
(2R,5R,6S,9S,10S,11R)-10-Hydroxy-2-[(1′S)-1′-Hydroxy-1′-methylpropyl]-5,11-dimethyl-9-(3-pyridylmethyl)6-(benzyloxycarbonylamino)-8-aza-1,4-dioxacyclododecane-3,7,12-trione and its 1′-O-methyl derivative, and (2S,1′R)-diastereomer of the latter have been enantiospecifically synthesized from sugar and l-threonine derivatives. The attempts to convert them into a pyridomycin precursor with the 2-(Z)-s-butylidene side chain were unsuccessful.
Kinetic Studies of Fast Equilibrium by Means of High-performance Liquid Chromatography. XII. Rate Constants and Energy Barriers of Intramolecular Carbonyl–Nitrogen Bond Rotation of o-Substituted Acetanilides
Authors: Moriyasu Masataka , Kawanishi Kazuko , Kato Atsushi , Hashimoto Yohei , Sugiura Makiko , Sai Torei 
Published: July 2006

Abstract
A novel high-performance liquid chromatographic(HPLC) method has been proposed to determine the rate constants and activation energies of the interconversion between two labile species existing in equilibrium in solution. The rotational energy barriers to intramolecular bond rotation about the carbonyl–nitrogen bonds of several o-substituted acetanilides have been determined by this method. These energy barriers have been found to increase when bulkier groups are attached at the o-position on the benzene ring. These have also been determined by a dynamic nuclear magnetic resonance spectroscopic(DNMR) method, which gives good agreement with the HPLC results.