Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 68 , Issue 7
Showing 1-41 articles out of 41 articles from the selected issue
  • Tomoyuki Akutagawa, Gunzi Saito
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1753-1773
    Published: 1995
    Released: July 09, 2006
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    The 2,2′-bi-1H-imidazole (H2BIM) derivatives were studied from the point of the interplay of proton-transfer (PT) and electron (charge)-transfer (CT) interactions. Seven new states among the speculated 25 independent species were identified based on the study of their redox and acid dissociation properties. Isoelectronic substitution of four sulfur atoms of the dication state of tetrathiafulvalene (TTF2+) by four imino groups was found to increase the stability of the dication state 2,2′-bi-1H-imidazolium (H4BIM2+) with aromatic 6π–6π character. The high PT character of H3BIM+ (2-(2-1H-imidazolyl)-1H-imidazolium) and H4BIM2+ compared with that of the corresponding hydroquinone system was clearly observed. The on-site Coulomb repulsion energy for electron-transfer (U1CT) was evaluated for various π-electron acceptor and donor systems. It was found that the U1CT values decrease linearly with increasing the length of a molecule, which can divide the molecular systems into two classifications, i.e. electron acceptors and dications. The on-site Coulomb repulsion energy for two-step proton-transfer processes (U1PT) was newly defined and evaluated for the H2BIM, H4BIM2+, hydroquinone (H2Q), and bis(4-hydroxyphenyl) disulfide (HPDS) systems. The U1PT values become constant above a certain molecular length (rc). Below rc the U1PT values increase linearly with decreasing the distance r regardless of Würster and Weitz structures, approximately. The H2BIM (H4BIM2+) system has large U1PT values in comparison with the H2Q and HPDS systems.
  • Masaki Matsumoto, Nobuyuki Nishi, Toshiya Furusawa, Masaru Saita, Tosh ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1775-1783
    Published: 1995
    Released: July 09, 2006
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    The structure of clusters in ethanol–water binary solutions at xE (ethanol mole fraction) ≥ 0.2 was investigated by the mass-spectrometric analysis of clusters isolated from liquid droplets and X-ray diffraction measurements of the intact solution. The average number of water molecules (Na) of the ethanol m-mer hydrates (5 < m < 15) in the mixtures at 0.2 ≤ xE ≤ 0.8 was found to be expressed by a function of the water mole fraction (xw), Na = {(m/4.2) − 1}2 (xw + 0.85), suggesting that the fundamental structure of ethanol polymer-hydrates is invariable in this region. An inflection point of Na was found at xE ≈ 0.2. The radial distribution functions (RDFs) from X-ray measurements demonstrated a decrease of linear hydrogen bonds at 2.8 Å with increasing xE, while keeping the strongest peak at 4.8 Å for 0.4 ≤ xE ≤ 1.0. On the basis of a composition analysis of the mass spectra and the concentration dependence of RDFs, we propose the most likely model of ethanol–water binary clusters formed in the region 0.2 ≤ xE ≤ 0.8.
  • Satoshi Kojima, Kazumasa Kajiyama, Kin-ya Akiba
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1785-1797
    Published: 1995
    Released: July 09, 2006
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    Diastereomeric phosphoranes (o-OC(CF3)2C6H4)2P*CH2CO2-(−)-menthyl (3-RP and 3-SP) of which absolute stereochemistry was determined were treated with LiAlH4 to give (o-OC(CF3)2C6H4)2P*CH2CH2OH (4-RP and 4-SP) as the first optically active pair of enantiomeric phosphoranes of rigid stereochemistry with asymmetry only upon the pentacoordinate phosphorus atom. The high enantiomeric purities of the alcohols were confirmed by converting them to their (+)-MTPA esters. Furthermore, when diastereomeric phosphoranes (o-OC(CF3)2C6H4)2P*CH2NHC*HCH3Ph (10-RP and 10-SP) of which absolute stereochemistry was also determined were treated with MeLi the first optically active pair of enantiomeric P–H phosphoranes (o-OC(CF3)2C6H4)2P*H (2-RP and 2-SP) with asymmetry only upon the pentacoordinate phosphorus atom could be obtained. The high enantiomeric purities of the P–H phosphoranes were confirmed by converting each of them to their corresponding (−)-menthyl esters 3-RP and 3-SP.
  • Manabu Kuroboshi, Tamejiro Hiyama
    1995 Volume 68 Issue 7 Pages 1799-1805
    Published: 1995
    Released: July 09, 2006
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    Iodofluorination of alkenes was achieved with N-iodosuccinimide, potassium hydrogendifluoride, and 1 M hydrofluoric acid using tetrabutylammonium fluoride as a phase-transfer catalyst. The active fluorinating reagent was shown to be tetrabutylammonium dihydrogentrifluoride by preparing the salt in a different way and by effecting the same transformation under anhydrous conditions. Bromofluorination of alkenes also was carried out using 1,3-dibromo-5,5-dimethylhydantoin. Treatment of the I–F adducts with DBU afforded fluoro olefins stereospecifically.
  • Biswajit Sarkar, Utpal Das, Subirnath Bhattacharyya, Swapan K. Bose
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1807-1809
    Published: 1995
    Released: July 09, 2006
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    The formation of inclusion complex between lumichrome and β-cyclodextrin was studied by fluorimetric and solubility methods. The accessibility of lumichrome to the iodide ion in presence of β-cyclodextrin was also studied. The equilibrium constant of formation of this inclusion complex, K, determined by fluorometric method and solubility method is 966 and 491 mol dm−3, respectively.
  • Shozo Yanagida, Hiroshi Kawakami, Yoshihide Midori, Hirotoshi Kizumoto ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1811-1823
    Published: 1995
    Released: July 09, 2006
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    Freshly prepared ZnS (nano-ZnS) suspensions catalyze photooxidation of organic substrates under band-gap irradiation with water as a good electron acceptor, while H2 evolves concomitantly. The organic substrates with hetero atoms or carbon–carbon double bonds (π-bonds), such as triethylamine (TEA), diethylamine (DEA), methanol, ethanol, cyclopentene, cyclohexene, 2-methylfuran, toluene, and ethylbenzene, undergo effective one-hole oxidation. This leads to efficient carbon–carbon bond forming reactions between cumulatively formed radicals at the α-carbon adjacent to the hetero atom or the π-bond. The photooxidation in the presence of a larger quantity of water results in successive oxidation of the intermediary α-carbon radicals, giving the two-hole oxidation products, e.g., DEA and acetaldehyde from TEA, and formaldehyde from methanol. The formation of the intermediary α-carbon radical has been clarified by ESR analysis using 2-propanol as an organic substrate. Semi-empirical molecular orbital calculations suggest that the nano-ZnS-catalyzed photooxidation should be predictable from energetics in the formation of the α-carbon radicals through one-hole oxidation and deprotonation, and from change in the bond order of αC–H bond of the α-carbon cation radicals.
  • Krishna N. Mehrotra, Rajeev K. Shukla, Mithlesh Chauhan
    1995 Volume 68 Issue 7 Pages 1825-1831
    Published: 1995
    Released: July 09, 2006
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    Infrared spectral studies of lanthanide soaps (octanoates of cerium, didymium, neodymium, and samarium) reveal that fatty acids exist with a dimeric-type structure through hydrogen bonding between two molecules of fatty acids, whereas the metal-to-oxygen bonds in these soaps have an ionic character. The X-ray diffraction results confirm that these soaps have a double-layer structure with molecular axes slightly inclined to the basal plane. The premicellar association and the formation of micelles in lanthanide soap solutions have been investigated by conductometric measurements in a nonaqueous medium. The molar conductance at infinite dilution, the degree of ionization and the ionization constant have been evaluated. The results show that these soaps behave as weak electrolytes in dilute solutions.
  • Hitoshi Matsuki, Michio Yamanaka, Shoji Kaneshina
    1995 Volume 68 Issue 7 Pages 1833-1838
    Published: 1995
    Released: July 09, 2006
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    The surface tension and densities of aqueous solutions of micelle-forming local anesthetic dibucaine and tetracaine salts having different halide ions as counterions from each other (dibucaine hydrochloride (DC·HCl), hydrobromide (DC·HBr) and hydroiodide (DC·HI), and tetracaine hydrochloride (TC·HCl) and hydrobromide (TC·HBr)) were measured as a function of the molality at 298.15 K under atmospheric pressure. The thermodynamic quantities of adsorption and volume for the anesthetics were evaluated numerically based on the experimental results. The surface densities of the anesthetics increased in the order of chloride, bromide, and iodide salts. This behavior may result from differences in the degree of three factors, that is, a hydration interaction between water molecules and counterions, the counterion distribution in the surface-adsorbed film, and ion-pair formation in the adsorbed film between anesthetic cations and counterions. It was further shown from the surface pressure vs. area per adsorbed molecule curves that the adsorbed films of the anesthetics undergo a phase transition from a gaseous state to an expanded state at low concentrations. On the other hand, the volumes of micelle formation for DC·HCl and DC·HBr have been found to be almost equal to each other. This fact means that the effect of these halide counterions on the volume of micelle formation is considerably small in contrast to the results of surface adsorption.
  • Akiko Okumura, Yuko Matsumiya, Kasumi Yamamoto, Reiko Ueno, Mariko Suz ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1839-1849
    Published: 1995
    Released: July 09, 2006
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    The rates (R) of the oxygen exchange of arsenic acid with solvent water were measured over a wide range of hydrogen-ion concentrations. At pH > 4, a 18O tracer method was used ([As(V)] = 0.07 mol dm−3, 0—50 °C). At pH < 5, 17O NMR line broadening technique was used ([As(V)] = 1 mol dm−3, 50—90 °C). Over the whole pH range studied, the variation of R amounts to 1010, and the comprehensive rate law is expressed as: R = k11h[H+][H3AsO4] + k11[H3AsO4] + k12[H2AsO4] + k13[HAsO42−] + k14[AsO43−] + k21[H3AsO4]2 + k22[H3AsO4][H2AsO4] + k23[H2AsO4]2 + k24[H2AsO4][HAsO42−] + k25[HAsO42−]2. The rate constant for each elementary process in the equation was obtained. The activation parameters of each elementary process were evaluated. The oxygen exchange rate of arsenic acid was compared with that of phosphoric acid. The contrast of an SN2-type exchange of the former acid vs. an SN1-type one of the latter is suggested.
  • Yasuko Takahashi, Fumie Miki, Kazuko Nagase
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1851-1857
    Published: 1995
    Released: July 09, 2006
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    Chitin [partially deacetylated β-(1→4)-linked 2-acetamide-2-deoxy-β-D-glucopyranose, (GlcNAc)n] was hydrolyzed by hydrochloric acid under the ultrasound irradiation. The first seven members of (GlcNAc)n in the degradation fluid were analyzed with high performance liquid chromatography (HPLC). The produced amounts of (GlcNAc)1—7 obtained by the degradation in concd HCl increased almost in proportion to the degradation time up to 120 min when sonolysis was used concomitantly. The yield of saccharides in the degradation fluid by concd HCl with sonolysis was about 2—4 times as much as that in the hydrolysis without sonolysis. The yield(%) increased with increasing of the concentration of HCl (6—12 mol dm−3) but decreased with increase of the concentration of chitin, showing a solvent volume effect. For the production of higher oligosaccharides, such as (GlcNAc)5—7, degradation with sonolysis for not longer than two hours is desirable. Deacetylated products were negligible. The effect of sonolysis is discussed from the aspect of the interactions of water with saccharide chains.
  • Elaheh K. Goharshadi, Ali Boushehri
    1995 Volume 68 Issue 7 Pages 1859-1861
    Published: 1995
    Released: July 09, 2006
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    The pair-potential energy function for methane has been determined using a direct inversion of the experimentally reduced viscosity collision integrals obtained from the corresponding-states correlation. The potential obtained in this way is in reasonable agreement with the potential independently known from the crossed molecular-beam technique.
  • Hideta Ishihara, Koji Yamada, Tsutomu Okuda, Alarich Weiss
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1863-1866
    Published: 1995
    Released: July 09, 2006
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    The temperature dependence of the 81Br nuclear quadrupole resonance (NQR) frequencies and spin-lattice relaxation times (T1Q) of 81Br NQR have been measured in aluminum tribromide–ammonia (1/1), AlBr3·NH3, crystals. The 81Br NQR spectrum consists of 6 lines, which are ascribed to two AlBr3 groups. This has been confirmed by the observation of 27Al NQR using the 81Br ↔ 27Al spin echo double resonance method. A 81Br T1Q measurement revealed that the activation energies for the reorientation of the AlBr3 groups or the molecular tumbling of AlBr3·NH3 are 61.1 and 81.6 kJ mol−1. The difference in the activation energies was reflected in the temperatures of the fade-out of the 81Br NQR lines at Tf = 320 and 350 K, respectively.
  • Fulvio Corradini, GianCarlo Franchini, Andrea Marchetti, Mara Tagliazu ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1867-1872
    Published: 1995
    Released: July 09, 2006
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    Dynamic viscosity (η) of binary solvent mixtures of N,N-dimethylformamide (DMF, component 1) + 2-methoxyethanol (ME, component 2) has been investigated at 19 temperatures ranging from −10 to +80 °C. Some empirical equations have been applied in order to establish the best regression fitting procedures η = η(T), η = η(X1) and η = η(T, X1). For this binary solvent system, the viscometric properties are continuous but not linear functions of the mixture composition. Therefore, experimental η values were used to calculate the excess viscosities (ηE) and excess Gibbs activation energies (ΔG*E) of viscous flow. Both these quantities strongly deviate from ideality over the whole composition range of the investigated mixtures. Furthermore, deviations from the ideal behaviour could be very useful in order to evidentiate the formation of solvent–cosolvent complex species and to evaluate their stoichiometrical composition.
  • Shigeyoshi Sakaki, Kazuya Mine, Taisuke Hamada, Toru Arai
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1873-1882
    Published: 1995
    Released: July 09, 2006
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    The formation reaction of oxanickelacyclopentene from [Ni(PH3)], hydroxyacetylene (a model of ethoxyacetylene), and carbon dioxide was investigated by the ab initio MO/SD-CI method. Of the two possible products of oxanickelacyclopentene and , the former was yielded with a lower activation energy (Ea) of 27 kcal mol−1 and a higher exothermicity (Eexo) of 31 kcal mol−1 than the latter (Ea = 38 kcal mol−1 and Eexo = 25 kcal mol−1). This result is consistent with the regioselectivity experimentally observed in the Ni(0)-catalyzed 2-pyrone synthesis from ethoxyacetylene and carbon dioxide. The regioselectivity of this reaction and the reactivity of hydroxyacetylene are discussed in terms of the energy level and the shape of the hydroxyacetylene π* orbital.
  • Fumio Shimizu, Yoshio Suzuki, Keiko Mitarai, Mitsuyo Fujino, Hiroshi K ...
    1995 Volume 68 Issue 7 Pages 1883-1888
    Published: 1995
    Released: July 09, 2006
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    The effects of pressure on the frequencies and band structures of the Raman active inter- and intramolecular vibrations of the 1,2,4,5-tetrabromobenzene crystal were studied under hydrostatic pressures upto 5 GPa at 300 K in a gasketed diamond anvil cell. Changes of the Raman frequencies and band structures of the inter- and intramolecular vibrations induced by pressure suggest that the phase transition takes place under about 0.7 GPa. Comparison of the pressure-induced frequency shifts of the inter- and intramolecular vibrations of the 1,2,4,5-tetrabromobenzene crystal with the frequency shifts observed in the 1,2,4,5-tetrachlorobenzene crystal indicates that the repulsive force between bromine atoms belonging to the adjacent molecules is fairly stronger than the force between chlorine atoms.
  • Hidetomo Noda, Shoichiro Ikeda, Akio Yamamoto, Hisahiko Einaga, Kaname ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1889-1895
    Published: 1995
    Released: July 09, 2006
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    The kinetics of the CO formation by electrochemical reduction of carbon dioxide on a gold electrode investigated in a series of potassium phosphate buffer solutions. CO is the principal product under the above condition. Small amounts of hydrocarbons, such as CH4, C2H4, and C2H6, are detected in the solutions of pH 5.2, 6.2, and 6.8. The Tafel slopes of the partial current density for the CO formation, ICO, at different pH are all ca. −120 mV/decade. The reaction mechanism has been proposed on the basis of the relationships between ICO and the electrode potential and between ICO and the reaction order with respect to CO2, which is ca. 1.
  • Takayuki Miyamae, Koji Kamiya, Shinji Hasegawa, Kazuhiko Seki, Chizuko ...
    1995 Volume 68 Issue 7 Pages 1897-1903
    Published: 1995
    Released: July 09, 2006
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    Sodium- and potassium-doped highly conducting polyacetylenes were studied by ultraviolet photoelectron spectroscopy (UPS) using synchrotron radiation. Upon doping, the UPS spectra immediately show a large shift toward the higher binding energy side relative to EF. At intermediate doping level, a new state is created in the empty energy gap region. The gap state in the UPS spectra is assigned to the charged soliton band. This is the first direct observation of emission from the charged soliton state in doped polyacetylene. At heavily doped level, the quasi-metallic density of states is found just below the Fermi level and the broadening of the UPS spectra occurs at the regions of C 2p and C 2s levels. However, no finite density of states was observed at the Fermi level in the case of unoriented polyacetylene. This result is in contrast to the case of oriented polyacetylene doped with perchlorate, where the existence of a finite density of states at EF is reported. The spectral shape of UPS near the Fermi level is in accordance with Tomonaga–Luttinger liquid model of strong electron correlated system. Ab initio molecular orbital calculations taking account of nearest-neighbor chain effect gives a good description of the UPS for all the C 2s, C 2pσ, and C 2pπ bands.
  • Takeshi Tabata, Hirofumi Ohtsuka, Mikako Kokitsu, Osamu Okada
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1905-1914
    Published: 1995
    Released: July 09, 2006
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    Adsorbed species during the reaction of selective catalytic reduction of NOx by hydrocarbons (HC-SCR) on Cu ion-exchanged ZSM-5 (Cu-ZSM-5) were investigated by in situ FT-IR using isotopes as well as gas phase analysis. No oxygen-containing species was observed by IR and no reaction proceeded in the presence of gaseous O2 and C2H4 below 473 K, at which HC-SCR occurs. However, an extra NOx species (tentatively assigned to organic nitrite or nitrate species), other than inorganic NOx species derived from O2 and NO, appeared very rapidly in IR at 1670 cm−1 at room temperature, in the presence of adsorbed NO2 species, gaseous C2H4 and NO. Afterwards, a carbonyl species (1677 cm−1) was formed gradually at room temperature. When the extra NOx species was observed, N2 and N2O evolved even at room temperature, therefore, the extra NOx species is considered to be related to HC-SCR. In the O2 + C2H4 + NO reaction at 473 K, no nitrogen-containing species, except for quite a small amount of nitrile (2168 cm−1), was observed in IR. At 473 K, N2, and CO evolved very rapidly with a steep increase in the IR intensity of carboxylate (1574 and 1375 cm−1), while CO2 and carbonyl species increased more slowly.
  • Yoshihiro Watanabe, Osamu Matsuoka
    1995 Volume 68 Issue 7 Pages 1915-1919
    Published: 1995
    Released: July 09, 2006
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    A method for segmented contractions of relativistic Gaussian basis sets is proposed, in which the large- and the small-component coefficients of the contracted basis sets are taken directly from the uncontracted relativistic basis sets and their kinetic balance is disregarded. The energy increases by this contraction scheme are found to be very small and the variational collapse does not occur. This method also reproduces very well the orbital energies and the radial expectation values of uncontracted basis sets. Examples of calculations on iodine (Z = 53), gold (Z = 79), and thorium (Z = 90) are reported in detail.
  • Kazuhisa Miyata, Masahiko Fujiwara, Junko Motonaka, Toshihiro Moriga, ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1921-1927
    Published: 1995
    Released: July 09, 2006
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    A micro enzyme-sensor, based on galactose oxidase (EC 1.2.3.9) and a tris(2,2′-bipyridine) complex of osmium(II/III) as a redox mediator ([Os(bpy)3]2+/3+), fabricated on a carbon electrode (25 μm diameter), was developed for measuring galactose. To obtain the carbon electrode, a platinum-disk electrode (25 μm diameter) was etched in hot aqua regia to create a cavity (depth of ca. 3—5 μm) at its tip. A porous carbon material was prepared from 90% acetylene black and 10% Teflon emulsion as a binder, and then packed into the cavity of the platinum-disk electrode’s tip. The carbon electrode was immersed in the osmium complex with 0.1 mol dm−3 LiClO4 in order to adsorb it in the carbon pores, which was monitored based on an increase in the anodic peak current and the cathodic peak current based on the osmium complex redox potential by the cyclic voltammogram. The tip of the carbon electrode was dipped overnight in a buffer solution of pH 7.00 containing galactose oxidase so as to immobilize it on this surface by adsorption. The characteristics of the porous-carbon material surface by X-ray diffraction (XRD) and scanning electron microscopy (SEM), the calibration curve for measuring of galactose, and the effects of the pH, temperature and concomitant compounds were investigated. By the XRD measurement, the porous carbon after treating a Zonyl FSN fluoro-carbon surfactant solution, a 5% Nafion® solution with methanol, and an osmium complex with 0.1 mol dm−3 LiClO4 showed good crystallinity compared with carbon powder. The structure of the carbon-electrode surface was visually confirmed using SEM photographs. The carbon surface had many pores, and galactose oxidase existed on it after adsorption. Under the optimum conditions the amperometric response of this sensor was linear over concentration ranges of 0.01—5.00 mmol dm−3 galactose; the correlation coefficient was 0.999.
  • Saeko Satake, Satoshi Tsukahara, Nobuo Suzuki
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1929-1933
    Published: 1995
    Released: July 09, 2006
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    The synergistic extraction of rare earth(III) ions (RE: La, Sm, Tb, and Lu) was investigated using a β-diketone (HA), i.e., trifluoroacetylacetone (Htfa) or hexafluoroacetylacetone (Hhfa), in the presence of a terdentate ligand, 2,2′:6′,2″-terpyridine (terpy) into benzene. The formation of complexes such as RE(A)2+ or RE(A)2+ in the aqueous phase was observed. The synergistic enhancement is attributed to the formation of an adduct RE(A)3terpy in the benzene phase. The adduct formation constants (βS,1) and the synergistic extraction constants were determined. For each RE(III), the βS,1 value in the Htfa–terpy system is smaller than that in the Hhfa–terpy system. The βS,1 values decrease with increasing atomic number of RE(III) in the Htfa–terpy system, but the βS,1 value for La(III) is smaller than that for the other RE(III) in the Hhfa–terpy system.
  • Shizuko Ambe, Fumitoshi Ambe
    1995 Volume 68 Issue 7 Pages 1935-1940
    Published: 1995
    Released: July 09, 2006
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    The Mössbauer emission spectra of defect 119Sn atoms arising from 119Sb and 119mTe were measured in GaSb, InSb, In2Te3, ZnSb, CdSb, CdTe, and Ag2Te. The lattice sites of defect 119Sn atoms in these binary compounds were determined on the basis of the obtained Mössbauer parameters and the recoil energy associated with EC decays of the source nuclides. Together with the results of previous studies, the isomer shifts of both defect and normal 119Sn were shown to correlate with the electronegativitity of ligands in binary compounds of the main-group elements, such as Sn, Sb, and Te.
  • Haruo Naruke, Kenji Yamada, Kazuyuki Kakegawa, Yoshinori Sasaki
    1995 Volume 68 Issue 7 Pages 1941-1945
    Published: 1995
    Released: July 09, 2006
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    A titanium sheet was selenidized in selenium vapor of 1.33—13.33 kPa at 823—973 K by means of a sealed-tube method. X-Ray diffraction patterns and an electron-probe microanalysis of the product films showed the layer to comprise only TiSe2. Since the selenidization obeyed a parabolic rate law under all of the conditions employed, the rate-determining step was a diffusion process. The parabolic rate constant (Kp) could be expressed as a function of the absolute temperature, and was approximately proportional to the partial pressure of Se2. A marker experiment indicated that selenium was the component which diffused in the product film.
  • Keiichi Tsukahara, Naoko Sawai, Satoko Hamada, Takashi Nakazawa, Ryoic ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1947-1954
    Published: 1995
    Released: July 09, 2006
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    N-3-Bromopropyl-5,10,15,20-tetraphenylporphyrinato(1-)chlorozinc(II), [Zn(BrPrtpp)Cl], catalyzed the formation of a methylviologen radical cation (MV+•) on steady-state irradiation of degassed methanol solutions with visible light (>420 nm) in the presence of triethanolamine (TEOA). The initial rate (Vi) of the formation of MV+• was of first order in the concentration of MV2+ and in the intensity of light and was independent of the concentration of TEOA above 0.025 M. Plots of Vi vs. the concentrations of [Zn(BrPrtpp)Cl] were curved. The fluorescence of [Zn(BrPrtpp)Cl]*, whose lifetimes are τ1s = 0.7 ns (48%) and τ2s = 2.0ns (52%) in methanol at 25 °C, was not quenched by MV2+. The excited triplet state of [Zn(BrPrtpp)Cl] (τ0t = 3.2 μs in MeOH) was efficiently quenched by MV2+ (kq = (6.0 ± 0.6) × 107 M−1 s−1 at 25 °C, 1 M = 1 mol dm−3). The thermal back electron-transfer reaction between [Zn(BrPrtpp)Cl]+• and MV+• was also observed (kb = (1.2 ± 0.2) × 1010 M−1 s−1). On the basis of the steady-state irradiation kinetics and ns-laser flash photolysis, the quantum yield of the excited triplet state of [Zn(BrPrtpp)Cl] can be evaluated to be 0.98 ± 0.02. [Zn(BrPrtpp)Cl] was found to be a more effective photocatalyst than [Zn(Prtpp)Cl] (HPrtpp = N-propyl-5,10,15,20-tetraphenylporphyrin) or [Zn(tpp)] (H2tpp = 5,10,15,20-tetraphenylporphyrin) under the present experimental conditions.
  • Keiji Ueno, Hiroshi Ogino
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1955-1958
    Published: 1995
    Released: July 09, 2006
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    Isomerization between two geometrical isomers of the methoxy-bridged bis(silylene)iron complex, anti-and syn-Cp*(OC)Fe{(SiMe2)···OMe···(SiMeOMe)} (Cp* = η5-C5Me5), was investigated by means of a variable-temperature 1H NMR experiment. The equilibrium constant (K) for the isomerization and its thermodynamic parameters were determined to be K = [syn-isomer]/[anti-isomer] = 0.53 at 293 K in toluene-d8, ΔG°298 = 1.5 ± 0.5 kJ mol−1, ΔH° = 3.8 ± 0.2 kJ mol−1, and ΔS° = 7.7 ± 1.0 J mol−1 K−1. Computer simulation of the VT spectra and calculation using Eyring equation yielded activation parameters, ΔH = 83.8 ± 3.2 kJ mol−1, ΔS = 42.3 ± 9.6 J mol−1 K−1, and ΔG298 = 71.2 ± 6.0 kJ mol−1, for the isomerization from the anti-isomer, in which the terminal OMe group is located on the opposite side of the Cp* group with respect to the Fe–Si–O(bridged)–Si ring, to the syn-isomer. A mechanism in which the bridging OMe group is replaced by the terminal OMe group is proposed for the isomerization.
  • Kouji Iida, Mamoru Nango, Kenichi Okada, Masaya Hikita, Mitsutaka Mats ...
    1995 Volume 68 Issue 7 Pages 1959-1968
    Published: 1995
    Released: July 09, 2006
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    Zinc hybrid porphyrin dimer(ZnTTP-C2-H2PFPP, ZnTTP-C2-H2TTP, ZnPFPP-C2-H2PFPP, and ZnPFPP-C2-H2TTP) and manganese (III) halogenated porphyrin dimers (MnPFPP-C2-MnPFPP, MnPFPP-C2-MnDCPP, and MnDCPP-C2-MnDCPP) covalently bridged by an ethylene moiety () were synthesized and characterized by UV-vis spectra, fluorescence spectra, and cyclic voltammograms. These porphyrin dimers could be embedded into the lipid bilayers of a liposomal membrane. The redox potential of the manganese complex for the halogenated porphyrin dimers increased with increasing of halogen portions on the porphyrin rings. An efficient energy transfer of the excited singlet state in the covalently-linked zinc hybrid dimers from zinc porphyrin to a free base porphyrin was observed, depending on the porphyrin structure. Furthermore, the manganese halogenated porphyrin dimers acted as catalysts of transmembrane electron transfer; such activity depends on the steric effect of halogen portions on the porphyrin ring.
  • Shuntaro Mataka, Hirohisa Kitagawa, Takehito Tsukinoki, Masashi Tashir ...
    1995 Volume 68 Issue 7 Pages 1969-1979
    Published: 1995
    Released: July 09, 2006
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    When heated in an alcoholic solvent, such as ethylene glycol or butanol, 4-substituted 3-aroyl-1-alkylpyrrolidines, which are readily accessible via the condensation of an amino acid, paraformaldehyde, and 3-substituted 1-ary-2-propen-1-one, afforded 4-substituted 1-alkyl-2-aryl-3-methylpyrrole derivatives in good yields. The ring-transformation of 3,4-dibenzoyl-1-methyl-2-phenylpyrrolidine occurred in two directions, giving the corresponding 3-benzyl- and 3-methylpyrrole derivative. Also, bicyclic pyrroles, such as 1H,3H-pyrrolo[1,2-c]thiazole, 2,3-dihydro-1H-pyrrolizine, and 5,6,7,8-tetrahydroindolizine, were prepared by the ring-transformation of bicyclic aroylpyrrolidines obtained from the corresponding cyclic amino acids. A mechanism for the ring-transformation is proposed.
  • Hiroaki Ozaki, Akiko Nakamura, Midori Arai, Masakazu Endo, Hiroaki Saw ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1981-1987
    Published: 1995
    Released: July 09, 2006
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    2′-Deoxyuridine derivatives bearing several kinds of amino-linker arms at C5 position were synthesized from 5-(methoxycarbonylmethyl)-2′-deoxyuridine and ethylenediamine, 1,6-hexanediamine, or tris(2-aminoethyl)amine. The modified nucleosides were incorporated into oligodeoxyribonucleotides at one or three positions in place of thymidine residues. The thermal stability of the duplexes was investigated. Three incorporations of ethylenediamine or tris(2-aminoethyl)amine at the C5-position increase the duplex stability. The amino-linker arm affected the stability of the duplexes depending on the number of amino groups in the linker arm and the length of the arm. The linker arm improved the nuclease resistance at 5′-side phosphodiester linkage of the modified nucleoside in oligodeoxyribonucleotides.
  • Toru Arai, Keisuke Kobata, Hisakazu Mihara, Tsutomu Fujimoto, Norikazu ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1989-1998
    Published: 1995
    Released: July 09, 2006
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    A novel template for the polypeptide–porphyrin hybrid, 5,10,15,20-tetrakis[2-(ethoxycarbonylmethoxy)phenyl]porphyrin (2) was synthesized in 17% yield. Four protected carboxyl groups are installed in 2 at the ortho-phenyl groups as the anchoring points, to which the N-termini of the polypeptides can be linked after the hydrolysis. Thus, 2 is a new analog of the porphyrin template tetrakis[2-(methoxycarbonyl)phenyl]porphyrin. The atropisomerization of 2 was much more rapid than that of tetrakis[2-(methoxycarbonyl)phenyl]porphyrin: At 353 K, 2 reached their equilibrium within 15 min. Such atropisomeric flexibility of 2 allows the self-organization of the α-helical peptide segments which are connected to 2. After the hydrolyses of the ethyl ester groups of 2, four α-helical 21-peptides, H–(–Gln–Leu–Leu–Gln–Ala–Leu–Ala–)3–NHCH2CH2OH were combined through the amide bonds to yield a new polypeptide–porphyrin hybrid (12). The polypeptide moieties of 12 showed typical α-helix profiles on circular dichroism measurements in methanol–water (3/1, v/v) and in Tris·HCl buffer solution. Thus, the four α-helix polypeptides are considered to fold into a bundle structure on the porphyrin template through the hydrophobic interaction. The circular dichroism spectrum of 12 in methanol showed an induced Cotton effect at the porphyrin region, and the CD band was symmetrically split. The hybrid (12) was also successfully incorporated into the egg yolk lecithin membrane almost quantitatively. When the molar ratio of egg yolk lecithin/12 was 500/1, the α-helix structure of the peptide segments in 12 was completely retained in the vesicles.
  • Hiroshi Nishino, Hideaki Hashimoto, James D. Korp, Kazu Kurosawa
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 1999-2009
    Published: 1995
    Released: July 09, 2006
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    The oxidation of 1,1,6,6-tetraaryl-1,5-hexadienes with manganese(III) acetate in the presence of malonamide gave two types of 5-exo cyclization products, 1-carbamoyl-8-diarylmethylene-3-azabicyclo[3.3.0]octan-2-ones and 3,10-dioxatricyclo[6.3.0.01,5]undecane-2,11-diones, in good to moderate yields. Similar reactions of 1,1,5,5-tetraaryl-1,4-pentadienes or 1,1,7,7-tetraaryl-1,6-heptadienes with malonamide yielded only complex mixtures, except for the formation of a small amount of 3,11-dioxatricyclo[7.3.0.01,5]dodecane-2,12-dione. On the other hand, 1,1,5,5-tetraaryl-1,4-pentadienes reacted with acetoacetamide in the presence of manganese(III) acetate to afford 3-carbamoyl-2-methyl-4-(2-propenyl)-4,5-dihydrofurans and 1,4-pentadienes substituted at the 3-position with acetoacetamide. A similar reaction of 1,1,6,6-tetraaryl-1,5-hexadienes with acetoacetamide gave 8-[acetoxy(diaryl)methyl]-3-oxabicyclo[3.3.0]octan-2-ones, 1-acetyl-8-diarylmethylene-3-azabicyclo[3.3.0]octan-2-ones, and 4-(3-butenyl)-3-carbamoyl-2-methyl-4,5-dihydrofurans. The selectivity of the inter- and intramolecular cyclizations containing the carboxamide moiety of malonamide or acetoacetamide is discussed.
  • Shunji Ito, Noboru Morita, Toyonobu Asao
    1995 Volume 68 Issue 7 Pages 2011-2016
    Published: 1995
    Released: July 09, 2006
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    The first example of a tri(1-azulenyl)methyl cation (2) containing a different substituent on each azulene ring was synthesized, and the dynamic stereochemistry was studied by temperature-dependent 1H NMR spectra. The dynamic behavior of 2 supported a one-ring flip mechanism and the validity of the flip mechanism for the analysis of the conformational change of the tri(1-azulenyl)methyl cations.
  • Takayasu Kawasaki, Masakatsu Watanabe, Hiromichi Ohta
    1995 Volume 68 Issue 7 Pages 2017-2020
    Published: 1995
    Released: July 09, 2006
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    It is proposed that arylmalonate decarboxylase (AMDase)-catalyzed decarboxylation proceeds via a thiol ester intermediate. Kinetics and CD spectra indicated that α-bromophenylacetate is a competitive inhibitor. TOF mass data indicated that the inhibitor bound with the enzyme through a thiol ester bond which was formed between a cysteine residue of the enzyme and the carboxyl group of the inhibitor. This result was also supported by reactivation of the enzyme by the addition of 2-mercaptoethanol, which is expected to cleave the enzyme–inhibitor bond via nucleophilic attack on the thiol ester linkage.
  • Isamu Inamura, Yuji Jinbo, Yoriko Akiyama, Yasuo Kubo
    1995 Volume 68 Issue 7 Pages 2021-2023
    Published: 1995
    Released: July 09, 2006
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    The densities were measured for dextran (Dex)–polyethylene glycol (PEG)–water, poly(1-vinyl-2-pyrrolidone (PVP)–PEG–water, and poly(vinyl alcohol) (PVA)–PEG–water systems. In all cases, the linear relationship of the density vs. concentration plots was not affected by the occurrence of liquid–liquid phase separation. The partial specific volumes were calculated from the slopes of the straight lines of the density.
  • Akihito Hashidzume, Atsushi Kajiwara, Akira Harada, Mikiharu Kamachi, ...
    1995 Volume 68 Issue 7 Pages 2025-2031
    Published: 1995
    Released: July 09, 2006
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    Trifluoroacetaldehyde azine (TFAcAz) was prepared and its reactivity was investigated. TFAcAz is readily attacked by nucleophiles such as trialkylamines, methanol, and water. The structures of the products were studied by 1H, 13C, and 19F NMR, IR, Raman, and EI–mass spectroscopies and X–ray crystallographic analysis. A cyclic dimer containing a 1,4-dihydro-1,2,4,5-tetrazine ring was obtained by the reactions of TFAcAz with trialkylamines. 1,2-Adducts were found to be produced by the reactions of TFAcAz with methanol and with water.
  • Tokunaru Horie, Takashi Kobayashi, Yasuhiko Kawamura, Isao Yoshida, Hi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 2033-2041
    Published: 1995
    Released: July 09, 2006
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    In the demethylation of 6-hydroxy-3,4′,7-trimethoxy-5-(tosyloxy)flavone with anhydrous aluminum bromide, the 5-tosyloxyl group was eliminated with bromination to give 8-bromo-3,6,7-trihydroxy-4′-methoxyflavone as the main product. When anhydrous aluminum chloride was used in the demethylation of the acetate, the 5-tosyloxyl group was cleaved prior to the demethylation to give 5,6,7-trihydroxy-3,4′-dimethoxyflavone. Demethylation of 6-hydroxy-4′,5,7-trimethoxy-3-(tosyloxy)flavone and its acetate with the bromide or chloride afforded the 5,6,7-trihydroxyflavone without the cleavage of the 3-tosyloxyl group, but was not suitable for the general synthesis of the 3,5,6,7-tetrahydroxyflavones because of the difficulty in removing the protecting group. Consequently, it was found that the direct demethylation of 3,6-dihydroxy-5,7-dimethoxyflavones with anhydrous aluminum chloride–sodium iodide in acetonitrile was the most useful general method for synthesizing 3,5,6,7-tetrahydroxyflavones. Additionally, the reported structures of two natural flavones were revised.
  • Shuzo Akiyama, Kunihiko Tajima, Shin’ichi Nakatsuji, Kenichiro N ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 2043-2051
    Published: 1995
    Released: July 09, 2006
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    A novel and facile method for direct C≡C acetylenic bond formation from the C=C double bond by treatment with potassium t-butoxide (t-BuOK) in N,N-dimethylformamide in the air has been found in a 9,10-bis(4-substituted styryl)anthracene series, in 4-substituted 4′-nitrostilbene series, and in 1-(p-nitrophenyl)-4-(p-substituted phenyl)-1,3-butadiene series; its scope and limitations have been examined. The ESR spectrum of the reaction against 4-diethylamino-4′ -nitrostilbene was measured to identify an anion radical species expected for explanation of the mechanism of the dehydrogenation reaction. Further, cyclic voltammetric measurements of a series of stilbenes and diphenylacetylenes were carried out in connection with the above mechanism. In many cases, interestingly, the use of a large excess of t-BuOK brought about succeeding hydroxylation into the ortho-position of a nitro group on the benzene nucleus. The simple hydroxylation is useful for the synthesis of substituted 5-(arylethynyl)-2-nitrophenols, which are expected to function as non-linear optical materials with the corresponding non-hydroxy compounds. The ultraviolet-visible and fluorescence spectral properties were measured and discussed also with those of the related compounds.
  • Iwao Hachiya, Mitsuhiro Moriwaki, Shu Kobayashi
    1995 Volume 68 Issue 7 Pages 2053-2060
    Published: 1995
    Released: July 09, 2006
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    Hafnium(IV) trifluoromethanesulfonate (hafnium(IV) triflate, Hf(OTf)4) was synthesized from hafnium tetrachloride and trifluoromethanesulfonic acid. The triflate thus prepared was found to be effective in the catalytic Friedel–Crafts acylation reactions of various substituted benzenes with acid anhydrides in lithium perchlorate–nitromethane (LiClO4–MeNO2). Lithium perchlorate–nitromethane is an excellent solvent system, and the catalytic activity of the Lewis acid was much improved in this medium. The product was obtained in up to 250000% molar amounts based on the catalyst. Hafnium(IV) triflate was also found to be quite effective in the catalytic Friedel–Crafts alkylation reactions of aromatic compounds with alkyl chlorides. The reactions proceeded smoothly in the presence of 5% molar amount of Hf(OTf)4 and 50% molar amount of LiClO4 by using a slow addition procedure.
  • Hiroshi Yokoi, Yasuyoshi Mori, Yutaka Fujise
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 7 Pages 2061-2065
    Published: 1995
    Released: July 09, 2006
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    The complex formation between iron(III) or copper(II) and poly(vinyl alcohol) (PVA) in aqueous solution has been investigated in some detail by using many PVAs ranging in degree of polymerization (DP) from 33 to 500. The minimum concentration of PVA required to form soluble complexes has been found to be inversely proportional to its DP, as expressed by the constancy of (DP of PVA) × [PVA]; the constants were 13 and 15 M in 10 mM iron(III) and copper(II) solutions (1 M = 1 mol dm−3), respectively. It has been revealed that iron(III) and copper(II) ions in the complexes exist in the form of metal hydroxide-like clusters comprising, at most, 120 metal ions per PVA chain. Transmission electron micrographs for the cast films of an iron(III) complex solution have shown the cluster size to be about 30 Å. Poly(vinyl methyl ether), a methyl ether derivative of PVA, was similar to PVA in complex formation with iron(III) up to pH 5. This fact also supports the conclusion that the present PVA complexes are of an inclusion type due to a hydrophobic interaction.
  • Ichiro Inami, Takao Baba
    1995 Volume 68 Issue 7 Pages 2067-2072
    Published: 1995
    Released: July 09, 2006
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    In some nuclear power plants, ion exchange resins for condensate purification systems show increasing rust removal efficiency year by year. In order to clarify this phenomenon, resin properties and rust behavior after adsorption on the resins have been studied. An adsorption test, a dissolution test and an ion exchanging test were performed in this study, using strongly acidic cation exchange resins, amorphous iron(III) hydroxide oxide and 55Fe tracer. It was found that aged cation exchange resins showed obvious property changes due to oxidative swelling, which induced better water mobility in the micropores. According to the property change, amorphous iron(III) hydroxide oxide, one of the iron rust components, is easily dissolved and diffused into resin beads, and consequently adsorption sites on aged resins are recovered rapidly compared with fresh resins. This is the reason for the superiority of the aged cation exchange resins in rust removal.
  • Mitsuho Yoshida, Eiji Osawa
    1995 Volume 68 Issue 7 Pages 2073-2081
    Published: 1995
    Released: July 09, 2006
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    A simple formalism for unfolding the fullerene structure onto a planar lattice is proposed. We recommend using deltahedra containing twelve penta-coordinated vertices as the geometrical precursors of fullerenes, and unfolding them onto a planar lattice according to Dürer’s style. This old style has several unique features that allow a priori drawing of diagrams that fold to fullerenes. Combined with the known algorithm for generating approximate atomic coordinates from the connectivity, which can be readily read off from the net diagram, the present method provides an alternative way of exhaustive generation of isomeric fullerene structures.
  • Mitsuho Yoshida, Eiji Osawa
    1995 Volume 68 Issue 7 Pages 2083-2092
    Published: 1995
    Released: July 09, 2006
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    The net drawing method of fullerenes presented in the preceding paper has been applied to the predictive studies on the movements of pentagonal rings accompanying skeletal transformations in fullerenes. The products of pyracylene rearrangements have been systematically generated to examine low-energy isomers containing abutting pentagons (so-called anti-IPR isomers) by performing the rearrangement only once on all the pyracylene units in each of the C60 to C100 isomers. The Endo-Kroto mechanism of C2-insertion into the carbon framework of fullerene has been likewise shown to be executable on paper. In this way, several energetically favorable pathways of growth have been found for C76 to C90. Potential applications of net drawing to the leapfrog and carbon cylinder operations and C2-elimination are also mentioned.
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