Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 71 , Issue 3
Showing 1-29 articles out of 29 articles from the selected issue
  • Zempachi Ogumi, Minoru Inaba
    1998 Volume 71 Issue 3 Pages 521-534
    Published: 1998
    Released: August 01, 2005
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    Electrochemical lithium intercalation within carbonaceous materials has attracted much attention for use to produce anodes in rechargeable lithium batteries. Although small-size rechargeable lithium cells using carbon anodes have been already commercialized, there still remain a lot of problems to be solved. Furthermore, recent global environmental issues require carbon anodes with high energy densities for use in electric energy storage and electric vehicles in the near future. This review article covers recent topics of the lithium intercalation, focusing on three fundamental aspects: intercalation processes, surface film formation, and lithium diffusion within carbons.
  • Akira Harada, Miyuko Okada, Mikiharu Kamachi
    1998 Volume 71 Issue 3 Pages 535-542
    Published: 1998
    Released: August 01, 2005
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    γ-Cyclodextrin (γ-CD) has been found to form inclusion complexes with poly(methyl vinyl ether) (PMVE), poly(ethyl vinyl ether) (PEVE), and poly(n-propyl vinyl ether) (PnPVE) of various molecular weights to give stoichiometric compounds in crystalline states. α-Cyclodextrin (α-CD) and β-cyclodextrin (β-CD) did not form complexes with poly(alkyl vinyl ether)s of any molecular weight. γ-CD did not form complexes with the low molecular weight analogs, such as diethyl ether and trimethylene glycol dimethyl ether. The yields of the complexes of γ-CD with PMVE increased with increasing molecular weight (MW) of PMVE and reached saturation at about MW 2000. The yields of the complexes of γ-CD with PEVE and PnPVE increased with increase in MW, reached a maximum at a MW of about 1000 for PEVE and about 250 for PnPVE, and decreased with a further increase in the MW. Complexes were isolated and found to have a 3 : 1 (monomer unit : CD) ratio. The complexes were characterized by IR, 1H NMR, 13C NMR, and X-ray (powder), thermal and elemental analyses. The structures of the complexes are discussed.
  • Mutsuko Oki, Kayako Hori
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 543-548
    Published: 1998
    Released: August 01, 2005
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    The crystal structures have been determined for 4′-octyloxybiphenyl-4-yl 4-cyanobenzoate (abbr. OCO-CN) and 4-methoxyphenyl 4′-octyloxybiphenyl-4-carboxylate (abbr. COO-OCH3) with the identical phase sequence of crystal 1 (CR1)-crystal 2 (CR2)-monolayered smectic A (SA1)-nematic (N)-isotropic. It is found that the combination of two factors, (1) opposite polarity of the terminal groups (electron-donating OCH3or -accepting CN) and (2) opposite direction of the central ester linkages, results in almost the same structures of CR1. They are composed of bilayers, in which the polar groups face each other. Methoxy groups are in van der Waals contact, while cyano groups have an unfavorable head-to-head arrangement. It is interpreted that this arrangement of CN groups is responsible for the large molecular rearrangements at the CR1–CR2 transition.
  • C. Sánchez, E. Leiva, S. A. Dassie, A. M. Baruzzi
    1998 Volume 71 Issue 3 Pages 549-554
    Published: 1998
    Released: August 01, 2005
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    Some aspects of direct ion transfer across water/1,2-dichloroethane have been analyzed using a very simple model based on thermodynamic considerations. It was concluded that ion solvation by water molecules may occur in some particular cases in the organic phase, delivering an important contribution to the Gibbs free energy of ion transfer between the aqueous and the organic phase. In general terms, this particular type of transfer should be favored in the case of highly charged small ions at interfaces with a relatively low surface tension and a large difference between the reciprocal of the corresponding dielectric constants.
  • Masud Shamsul Huda, Ryotaro Kiyono, Masayasu Tasaka, Takanori Yamaguch ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 555-562
    Published: 1998
    Released: August 01, 2005
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    The thermal membrane potential across anion-exchange membranes having various hydrophobic anion-exchange groups was measured for various electrolyte solutions. A good linear relationship between the thermal membrane potential (Δψ) and the logarithmic temperature difference (Δln T) was observed. The temperature coefficient of the thermal membrane potential (Δψ/Δln T) was found to be a function of the logarithmic activities of ions with a slope of RTc/F for 1-1 electrolytes and RTc/(2F) for 1-2 electrolytes, where Tc is the constant temperature of the solution on one side of the membrane. The absolute value of Δψ/Δln T decreased with increasing the molality of the external electrolyte solutions. The absolute value of Δψ/Δln T in KCl solutions was higher than that in KIO3 solutions. For halide ions the order of the absolute values of the thermal membrane potential (Δψ) was Cl > Br > I, which corresponds to the order of the values of the B-coefficient in the Jones–Dole expression for the viscosity of the solutions, but opposite to that of the conventional partial molar volume. For large oxoanions the order of the absolute values of Δψ was found to be NO3 > IO3 > SO42−, which is opposite to the order of the B-coefficient as well as to that of the molar volume of these hydrated ions.
  • Yunying Wu, Osamu Kawaguchi, Tsuneo Matsuda
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 563-572
    Published: 1998
    Released: August 01, 2005
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    The reforming reactions of CH4 with CO2 diluted with He on perovskite structural oxides, LaBO3 (B = Co, Ni, Fe, Cr), were examined. The reaction activity at 1073 K followed the order LaCoO3 > LaNiO3 > LaFeO3 > LaCrO3, and the highest selectivities to CO and H2 were obtained on a LaCoO3 catalyst. The reaction on the LaCoO3 catalyst under the reaction condition of CH4/CO2 = 1 showed a H2/CO ratio of 1; the ratio was less than 1 on other catalysts. In the initial stage of the reactions of CH4 + CO2 on LaCoO3 and LaNiO3 catalysts, an induction period accompanying the reduction of the catalysts was observed. During the reforming reaction, both the LaCoO3 and LaNiO3 catalysts were decomposed by reduction to Co to Ni metal and La2O3. No induction period, however, was observed in the reaction on the LaFeO3 and LaCrO3 catalysts, which were stable during the reaction. The high activity of the decomposed LaCoO3 catalyst is ascribed here —as a result of EPMA, SEM analysis and of comparison with the reaction behaviors of Co catalysts supported on La2O3 — to the high concentration of metallic cobalt uniformly dispersed as fine particles on the catalyst surface. The reaction mechanism on the cobalt metal was inferred from the results of the reaction of CH4 or CO2 alone on the decomposed LaCoO3 catalyst.
  • Yasunori Yoshioka, Shigehiro Kubo, Shinji Kiribayashi, Yu Takano, Kiza ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 573-588
    Published: 1998
    Released: August 01, 2005
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    Hubbard models for four-site four-electron {4,4} systems are analytically solved to elucidate group-theoretical interrelationships between effective model Hamiltonians for radical clusters, metal clusters, Cu4O4, and so on. The group operations used for this purpose are permutation group (SN), spatial symmetry (PN), spin rotation (S), and time-reversal (T). The magnetic (color) group (T × S) is utilized for determination of the magnetic symmetry of spin structures obtained on the basis of the classical Heisenberg model; namely a vector representation of radical spins. The magnetic double group theory (T × S × PN) is used for characterization of general Hartree–Fock solutions (GHF) involving axial, helical, and torsional spin density waves for {4,4} systems. The spin-optimized SCF solutions are constructed from the spin projection of the GHF solutions (T × S × PN) by the use of the permutation symmetry (SN). The SN group is also used for the quantum Heisenberg model for {4,4} systems. In order to show the interrelationships between these model Hamiltonians, the electronic states of {4,4} systems with the D4h, Td, and D3h symmetries are constructed by the use of the magnetically ordered general spin orbitals which have been determined by the GHF calculations. The spin-optimized SCF solutions for {4,4} systems examined here are equivalent to the full CI wavefunctions satisfying both spatial and spin symmetries. The relative contributions of the spin polarization (SP) and doubly excited configurations in the GHF, projected GHF and SO-SCF wavefunctions are clarified to elucidate possible mechanisms of spin alignments and antiferromagnetic spin correlations. Implications of these computational results are discussed in relation to quantum and classical representations of spin alignments in molecular magnetic materials such as iron–sulfur clusters. Molecular magnets having helical and torsional spin structures are designed and discussed in relation to the most general spin alignment in the species.
  • Ludovick Christian Manege, Tadaharu Ueda, Masashi Hojo
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 589-596
    Published: 1998
    Released: August 01, 2005
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    The solvolysis rates of aliphatic halides and related compounds (RX) were determined in an 80 vol% MeOH–20 vol% H2O solvent in the presence of very highly concentrated salts (0.25—5.0 mol dm−3) at 25—75 °C. For typical SN1 substrates, such as 1-adamantyl bromide and t-butyl chloride, the pseudo-first-order reaction rates (k/s−1) increased exponentially with increasing concentration of LiClO4, NaClO4, Mg(ClO4)2, and Ba(ClO4)2. The cation effects increased as Na+ < Li+ < Ba2+ ≤ Mg2+. A nonmetallic salt, Et4NBr, caused the k/s−1 value for 1-adamantly bromide to be slightly increased at lower concentrations ( < 1.0 mol dm−3), but to be greatly decreased at higher salt concentrations ( ≥ 2.0 mol dm−3). The large positive effects of metal perchlorates were explained by a change in the solvent structure and the formation of “stable” carbocations through a “chemical” interaction between X (Cl, Br, or I) and M+ (Li+, Na+) or M2+ (Mg2+, Ba2+) in the “modified” solvent. On the other hand, for SN1–SN2 intermediates, the solvolysis reaction rates were decreased by a decrease in the activity of the solvent containing a large amount of salts. The apparent rate constant (“k/s−1”) for isopropyl bromide at 75 °C remained an almost constant value in the presence of 0—5.0 mol dm−3 LiClO4. The rate constant for ethyl bromide was decreased substantially by the addition of the alkali metal and alkaline-earth metal perchlorates. A good linearity was observed between log (k1/k0) and the m values for RX by Grunwald and Winstein, where k1 and k0 are the solvolysis rates in the presence of 1.0 mol dm−3 LiClO4 and in the absence of the salt, respectively. Upon the solvolysis of neophyl chloride (1-chloro-2-methyl-2-phenylpropane), the change in the reaction scheme (e.g., methyl shift) was suspected during the increase in the LiClO4 or Ba(ClO4)2 concentration.
  • Mohammed S. El-Shahawi, Ali Z. Abu Zuhri
    1998 Volume 71 Issue 3 Pages 597-601
    Published: 1998
    Released: August 01, 2005
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    Two simple and accurate titrimetric and spectrophotmetric methods have been developed for the determination of tin. The methods were based upon the oxidation of tin to tetravalent tin with sodium periodate at pH 2.2—3.5; excess periodate ions were then masked with 5% sodium molybdate at the same pH. The released iodate ions were determined spectrophotometry (at 350 nm) as triiodide after the addition of KI. This proposed procedure offered a six-fold amplification for each tin(II) ion. Alternatively, the released iodine was extracted with chloroform and shaken with an aqueous solution of 1% (w/v) sodium sulfite. The iodide ions produced in the aqueous phase were then oxidized with sodium periodate after removing the unreacted sodium sulfite by boiling with H2SO4 (2 M). The released iodate was finally determined by iodometry or spectrophotometry. This procedure offered 144-fold amplification per tin(II) ion. The determination of tin(IV) after prior reduction to tin(II) with sulfur dioxide was also found to be suitable. Analyses of the binary mixtures of tin(II)–tin(IV) in an aqueous solution, tin in organotin compounds and tin(II) and tin(IV) in artificial sea-waters were successfully carried out.
  • Yuki Onoe, Satoshi Tsukahara, Hitoshi Watarai
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 603-608
    Published: 1998
    Released: August 01, 2005
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    The catalytic effect of N,N-dimethyl-4-(2-pyridylazo)aniline (PADA) on the extraction rate of Ni(II) with 1-(2-pyridylazo)-2-naphthol (Hpan) in toluene was investigated by the high-speed stirring method. The extracted species was only Ni(pan)2 under the highly stirred system. The extraction rate of Ni(pan)2 was proportional to both concentrations of Ni(pada)2+ adsorbed at the liquid–liquid interface and Hpan in the toluene phase, suggesting that the rate-determining step was the reaction between Ni(pada)2+ and Hpan at the interface, followed by a successive fast ligand-substitution reaction with another Hpan. The rate constant for the rate-determining step was estimated as 90 ± 6 M−1 s−1. That the value was rather smaller than the ordinary formation rate constants of Ni(II) complexes was explained by the ring-closure mechanism in the coordination of Hpan.
  • Minori Uehara, Mika Urade, Yuriko Abe
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 609-617
    Published: 1998
    Released: August 01, 2005
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    The preparation of [Mn(saltnOCOPh)Cl]·DMF (H2saltnOCOPh: N,N′-(2-benzoyloxypropane-1,3-diyl)bis(salicylideneamine)) and kinetics and mechanisms of H2O2 disproportionation catalyzed by mononuclear Schiff base manganese(III) complexes, such as [Mn(salen)Cl] (H2salen: N,N′-ethylenebis(salicylideneamine)), [Mn(saltn)Cl] (H2saltn: N,N′-propane-1,3-diylbis(salicylideneamine)), [Mn(saltnOH)Cl] (H2saltnOH: N,N′-(2-hydroxypropane-1,3-diyl)bis(salicylideneamine)), and [Mn(saltnOCOPh)Cl] in N,N-dimethylformamide (DMF), have been investigated. The disproportionation of H2O2 to O2 and H2O proceeds coupled with the redox cycle between the Mn(III) complex and the Mn(IV) intermediate: the first step is the fast equilibrium (Km) of the Mn(III) complex and the Mn(IV) intermediate formed by the reaction of the Mn(III) complex with H2O2, followed by a slow reaction (k1) of the Mn(IV) intermediate with H2O2 to produce O2 and H2O recovering the original Mn(III) complex. The Km values decrease in the following order: [Mn(salen)Cl] (728 mol−1 dm3) >> [Mn(saltnOH)Cl] (28.0 mol−1 dm3) > [Mn(saltn)Cl] (6.28 mol−1 dm3) > [Mn(saltnOCOPh)Cl] (1.83 mol−1 dm3), reflecting an increased distortion along the axis containing the coordination of H2O2 to the Mn(III) complex. On the other hand, the rate constants (k1) fall into the following sequences: [Mn(saltnOH)Cl] (4.29 × 105 mol−2 dm6 s−1) > [Mn(salen)Cl] (1.67 × 105 mol−2 dm6 s−1) > [Mn(saltnOCOPh)Cl] (3.34 × 104mol−2 dm6 s−1) > [Mn(salen)Cl] (6.15 × 103 mol−2 dm6 s−1). In spite of the small Km values for saltnOH, saltnOCOPh, and saltn complexes with the 1,3-diamine ligand, compared to that for the salen complex, the large k1 value for the saltnOH complex strongly suggests stabilization of the transition state for the formation of hydrogen-bondings among the Mn(IV) intermediates and H2O2. Futhermore, the effect of the OH ion on the H2O2 disproportionation catalyzed by [Mn(salen)Cl] has been reported. On account of the formation of [Mn(salen)OH] coordinated by the OH ion, the appearance of the reaction path involving not only the Mn(III)–Mn(IV) cycle, but also the Mn(II)–Mn(III) cycle, is shown based on the ESR and visible spectral studies. The activity for the Mn(II)–Mn(III) cycle is 20 times larger than that for the Mn(III)–Mn(IV) cycle.
  • Takeyoshi Yagyu, Sen-ichi Aizawa, Shigenobu Funahashi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 619-629
    Published: 1998
    Released: August 01, 2005
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    Several solvated palladium(II) complexes with the potentially cyclopalladating dibenzyl ligand have been synthesized. These include [Pd(CH3CN)(Bn2Medptn)](BF4)2 (1) (Bn2Medptn = N, N′-dibenzyl-4-methyl-4-azaheptane-1,7-diamine), [Pd(dmf)(Bn2Medptn)](BF4)2 (2) (dmf = N,N-dimethylformamide), and [Pd(dmso)(Bn2Medptn)](BF4)2 (3) (dmso = dimethyl sulfoxide), their cyclopalladated complex, [Pd(H−1Bn2Medptn-C,N,N′,N″)]CF3SO3 (4), the solvated monobenzyl complex, [Pd(CH3CN)(BnMedptn)](BF4)2 (5) (BnMedptn = N-(3-aminopropyl)-N′-benzyl-N-methyl-1,3-propanediamine), and its deuterated complex, [Pd(CH3CN)(BnMedptn-d7)](BF4)2 (6) (BnMedptn-d7 = N-(3-aminopropyl)-N′-heptadeuteriobenzyl-N-methyl-1,3-propanediamine). The crystal structures of 1·CH3CN·CH2Cl2, 2, and 4 have been determined by X-ray structure analysis to characterize the reactant and the product for the cyclopalladation of the solvated complexes, where one of the ortho carbons of 1 is directed toward the palladium(II) center (Pd···C(1) = 3.513(9) Å). The rate constants for the cyclopalladation of 1 at 25 °C in various solvents increase in the order DMF < DMSO << pyridine, but the reaction does not proceed in acetonitrile or nitromethane. The activation parameters for the cyclopalladation in neat solvent have been obtained as follows: k298 = 5.74 × 10−6 s−1, ΔH = 104.0 ± 1.2 kJ mol−1 and ΔS = 3.5 ± 3.9 J K−1 mol−1 for 1 in DMF, k298 = 3.13 × 10−4 s−1, ΔH = 83.8 ± 2.6 kJ mol−1 and ΔS = −31.0 ± 8.8 J K−1 mol−1 for 1 in DMSO, k298 = 1.30 × 10−4 s−1, ΔH = 81.2 ± 0.5 kJ mol−1 and ΔS = −47.0 ± 1.8 J K−1 mol−1 for 5 in DMF, k298 = 1.76 × 10−3 s−1 for 5 in DMSO, k298 = 1.26 × 10−5s−1, ΔH = 92.8 ± 1.4 kJ mol−1 and ΔS = −27.5 ± 4.4 J K−1 mol−1 for 6 in DMF and k298 = 2.69 × 10−4 s−1 for 6 in DMSO. The activation enthalpy is reduced as the solvent basicity increases. The kinetic isotope effects (kH/kD) for the cyclopalladation of the monobenzyl complex at 25 °C are calculated to be 10.3 in DMF and 6.5 in DMSO using the rate constants for 5 and 6. It is confirmed from the kinetic results obtained that the nucleophilic attack of the basic solvent on the ortho proton is essential for the C–H bond cleavage observed in the activation process. In addition, the fact that the rate constant for the cyclopalladation is proportionally dependent on the concentration of DMSO in nitromethane strongly suggests that the solvent-dissociation pre-equilibrium is negligible in neat basic solvent.
  • Jun Mizutani, Setsuko Yajima, Hideo Imoto, Taro Saito
    1998 Volume 71 Issue 3 Pages 631-636
    Published: 1998
    Released: August 01, 2005
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    A trinuclear molybdenum chloro sulfido cluster complex [Mo3S4Cl4(C5H5N)5] (1) was synthesized by the excision of a nonmolecular cluster compound Mo3S7Cl4 with triphenylphosphine and pyridine. Three molybdenum atoms and four sulfur atoms form an incomplete cubane-type cluster core, which is coordinated by four chloro and five pyridine ligands. By the reaction of 1 with I2 in pyridine, [Mo3S4Cl3(C5H5N)6]I (2) was synthesized. Three μ-S in the cluster cation and the iodine anion have short contacts, within the sum of the van der Waals radii of sulfur and iodine.
  • Manabu Harata, Koichiro Jitsukawa, Hideki Masuda, Hisahiko Einaga
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 637-645
    Published: 1998
    Released: August 01, 2005
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    Mononuclear copper complexes with a tripodal tetradentate ligand, tris(6-pivaloylamino-2-pyridylmethyl)amine (Htppa), and several anions have been prepared as a model metal centre of copper enzymes, whose structures have been examined by electronic absorption, ESR and NMR spectral, cyclic voltammetry, and X-ray diffraction methods. Those with an anion such as OH, Cl, Br, and I were shown to form a trigonal-bipyramidal geometry. The X-ray structures of [Cu(Htppa)](ClO4)2·2H2O·CH3OH, [CuCl(Htppa)]ClO4, [Cu(OH)(Htppa)]ClO4, [Cu(OH)(tppa)], and [Cu(tppa)](BPh4), obtained as a single crystal, revealed all trigonal-bipyramidal geometry with four nitrogen atoms of Htppa in trigonal plane and axial position and with the anion in another apical position. The reaction with NaN3 gave [Cu(N3)2(Htppa)], whose crystal structure was a square-pyramid with three nitrogen atoms of Htppa and N3 in square-planar positions and with another N3 in apical position. The redox potentials of [CuCl(Htppa)]ClO4 in MeCN or CH2Cl2 showed almost reversible CuI/CuII couples at 0.225 and 0.300 V vs. Ag/AgCl, respectively, which are characteristically high for the usual copper complexes. The addition of dioxygen to the Cu(I)–Htppa complex prepared from [Cu(MeCN)4]ClO4 and Htppa (1 : 1) in methanol solution at −78 °C resulted in an immediate absorption spectral change, with two well-separated absorptions at 657 (ε = 110 M−1 cm−1) and 803 nm (ε = 120 M−1 cm−1) and an intense band at 315 nm (ε = ca. 4000 M−1 cm−1) as a shoulder. Simultaneous ESR experiments of the same complex solution exhibited a silent spectrum, and the NMR spectrum at −80 °C was diamagnetic. These facts indicate the formation of CuII–O2species. Interestingly, the CO gas bubbling into a CH3OH/THF/EtCN (4 : 3 : 3) solution of the superoxo complex species at −78 °C led to a significant color change from yellow-green to pale yellow, and alternate bubblings of O2 and CO to the solution exhibited a reversible spectral change with an isosbestic point at 521 nm due to the reversible formation of the CuII–O2 species.
  • Hiroshi Kawaguchi, Tokuo Shimizu, Takashi Shirakashi, Yoshio Shijo
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 647-650
    Published: 1998
    Released: August 01, 2005
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    A method for the determination of gallium at ng dm−3 levels in river water is described. Gallium is extracted into carbon tetrachloride as an ion pair of gallium–5-sulfo-8-quinolinol (H2QS) chelate anion with tetradecyldimethylbenzylammonium chloride (Zephiramine), and subsequently back-extracted into 0.3 cm3 of a nitric acid solution. The high efficiency of extraction and back extraction allows gallium to be concentrated about 5000-fold with a combined single extraction and back extraction. The back-extracted solution, containing 250 μg cm−3 of nickel as a matrix modifier, is suitable for the determination of gallium by electrothermal atomic absorption spectrometry (ETAAS). The detection limit (3σ) for gallium is 0.29 ng dm−3 based on a 1500-fold preconcentration. The concentration of dissolved gallium in river water was found to be 5.3—9.2 ng dm−3 by the proposed method.
  • Yong Che, Koichi Tokuda, Takeo Ohsaka
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 651-656
    Published: 1998
    Released: August 01, 2005
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    Linear solvation energy relationships for solution of O2 in 27 solvents have been examined. Multiple linear regression equations for mole fraction solubility of O2 are developed based on Hildebrand’s solubility parameter as well as the π*, α, and β solvatochromic parameters describing the solvent polarizability/dipolarity, hydrogen bond acidity and hydrogen bond basicity, respectively. Use of the combination of these parameters enables the medium effect on solution of O2 to be correlated and interpreted in a conceptually simple manner.
  • Keiichi Kimura, Yutaka Tsujimura, Masaaki Yokoyama, Takumi Maeda
    1998 Volume 71 Issue 3 Pages 657-660
    Published: 1998
    Released: August 01, 2005
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    An oligo(dimethylsiloxane) carrying ionophorous calix[4]arene moieties at the side chain was synthesized as a Na+ neutral carrier for highly durable silicone-rubber membranes of ion-selective electrodes by reacting calix[4]arene tetraallyl ester with an oligo(methylsiloxane). This medium-molecular-weight calix[4]arene ionophore alleviated the drawback of chemically-modified calixarene-based silicone-rubber membranes, such as a high membrane impedance and a slow electrode response.
  • Yoshitaro Miyashita, Narumi Sakagami, Yasunori Yamada, Takumi Konno, J ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 661-670
    Published: 1998
    Released: August 01, 2005
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    S-Bridged trinuclear complexes, [CrIII{M(aet)3}2]3+, (M = RhIII (1), IrIII (2); aet = NH2CH2CH2S) were newly prepared by the reaction of fac(S)-[M(aet)3] with chromium(III) nitrate. They were separated and optically resolved into the ΔΔ, ΛΛ, and ΔΛ isomers. Of these isomers for 1 and 2, the crystal structures of the ΔΛ isomers (1a and 2a) were determined by an X-ray diffraction method. Each of 1a and 2a consists of two fac(S)-[M(aet)3] subunits, a central Cr atom, three nitrates, and three water molecules, [Cr{M(aet)3}2](NO3)3·3H2O, in which three metals are aligned so as to be exactly linear. The central Cr atom is situated in an octahedral environment with the CrIIIS6 chromophore, which is formed by the coordination of two terminal fac(S)-[M(aet)3] units. The other isomers for 1 and 2 were characterized by the absorption and CD spectra, the molar conductivity, and the magnetic susceptibility. Each cyclic voltammogram of ΔΛ-[Cr{M(aet)3}2]3+ in water showed a reversible redox couple (M(IV)/M(III)) and an irreversible reduction wave (Cr(III)/Cr(II)). The stabilities of the S-bridged MCrIIIM complexes are also discussed in relation to the Cr–S bond strengths.
  • Hideki Furutachi, Hisashi Okawa
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 671-677
    Published: 1998
    Released: August 01, 2005
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    The CoIIPbII complex [CoPb(L)(CH3OH)(ClO4)2] reacts with nitrogen monoxide to give the nitrosyl complex [CoPb(L)(NO)(dmf)2(ClO4)]ClO4 (1), where H2L is a dinucleating macrocycle derived from the [2 : 1 : 1] condensation of 2,6-diformyl-4-methylphenol, ethylenediamine, and diethylenetriamine and has a “salen”- and a “saldien”-like metal-binding site sharing the phenolic entities. 1 crystallizes in the triclinic space group , a = 12.729(4), b = 17.103(6), c = 10.548(4) Å, α = 107.42(4)°, β = 106.18(2)°, γ = 101.33(3)°, V = 2003(1) Å3, and Z = 2. The refinement converges with R = 0.045 and Rw = 0.049 for 3768 reflections with I > 3.00σ(I). The Co resides in the “salen” site and the Pb in the “saldien” site. The metal ions are bridged by the two phenolic oxygens of L2− and a dmf oxygen, in the Co–Pb intermetallic separation of 3.511(2) Å. The Co–O(dmf) and O(dmf)–Pb bond distances are 2.14(1) and 3.072(8) Å, respectively. The NO coordinates to the Co at the axial site trans to the bridging dmf oxygen, providing a six-coordinate geometry about the metal; the Co–N(nitrosyl) distance is 1.92(1) Å and the Co–N–O angle is 117(1)°. The Pb has an eight-coordinate geometry together with the bridging dmf oxygen, a terminal dmf oxygen and a perchlorate oxygen. The nitrosyl complex 1 is oxidized with molecular oxygen to the nitro complex [CoPb(L)(NO2)(dmf)2(ClO4)]ClO4 (2). 2 crystallizes in the triclinic space group , a = 12.748(4), b = 17.139(5), c = 10.359(3) Å, α = 106.34(3)°, β = 106.44(3)°, γ = 101.42(3)°, V = 1986(1) Å3, and Z = 2. The refinement converges with R = 0.039 and Rw = 0.042 based on 6202 reflections with I > 3.00σ(I). 2 has a dinuclear core very similar to that of 1, bearing an NO2 group instead of an NO group. The Co–N(nitro) bond distance is 1.889(6) Å. 1H NMR, 13C NMR, and 13C–1H COSY spectroscopies indicate that the dmf-bridged dinuclear cores of 1 and 2 are retained in solution.
  • Nobuo Sakairi, Yasunori Okazaki, Jun-ichi Furukawa, Hiroyoshi Kuzuhara ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 679-683
    Published: 1998
    Released: August 01, 2005
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    A (+)-10-Camphorsulfonic acid-catalysed acetal exchange reaction of phenyl 1-thio-β-laminaribioside using 3.5 molar equivalents of α,α-dimethoxytoluene gave a tris(benzylidene acetal), which was isolated and characterized as phenyl 3′-O-acetyl-2,2′ : 4,6 : 4′,6′-tri-O-benzylidene-1-thio-β-laminaribioside, and the corresponding 3′-O-benzyl derivative 6. Upon a treatment with pyridinium p-toluenesulfonate, the interglycosidic 2,2′-acetal in 6 underwent selective cleavage to give the 2,2′-diol. Additionally, a reductive ring-opening reaction of 6 with lithium aluminium hydride/anhydrous aluminium chloride, followed by O-acetylation, gave the 2,6,6′-O-acetyl-4,2′,3′,4′-tetra-O-benzyl derivative in 73% yield. A different regioselectivity was observed in the reduction of 6 with borane-trimethylamine adduct/anhydrous aluminium chloride or sodium cyanotrihydroborate/methanesulfonic acid, giving the corresponding 2,4,4′-triol as the major product.
  • Yoshiaki Kusuyama
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 685-691
    Published: 1998
    Released: August 01, 2005
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    The solvolyses of 1-[trans-2-(m- or p-substituted phenyl)cyclopropyl]-1-methylethyl p-nitrobenzoates in 80% aqueous acetone have been studied with regard to both reactivity and product composition. For the less reactive substituents such as m-Br, m-Cl, and m-CF3, the solvolysis products were the corresponding 2-(2-arylcyclopropyl)-2-propanol, indicating the cyclopropylmethyl cation intermediate. The ring-opened products increased as the electron-donating ability of the substituents increased. The application of the Yukawa–Tsuno equation to the reactivity afforded a ρ value of −1.43 and r value of 0.59 with a correlation coefficient of 0.997. A large value of r indicates the presence of the allylic cation intermediate where much more charge develops at the benzylic carbon for the derivatives with electron-donating substituents than is the case for the cyclopropylmethyl cation intermediate. Thus the solvolysis reaction proceeds via two independent pathways: one has a cyclopropyl cation intermediate and the other has a homoallylic cation intermediate.
  • Masahiro Minabe, Toshiya Nozawa, Tomoko Kurose, Takao Kimura, Motohiro ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 693-697
    Published: 1998
    Released: August 01, 2005
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    9-(Tropylidenehydrazono)fluorene (1) was obtained by a reaction between 9-fluorenone hydrazone and tropylium tetrafluoroborate, accompanied by 9-fluorenone azine, 9-(benzylidenehydrazono)fluorene, and 9,9-ditropylfluorene. The amination of 1 occurred at the 2-position of the tropylidene moiety. The addition of tosyl isocyanate to 1 gave the [8 + 2] cycloadduct at the 2,4,6-cycloheptatrien-1-imine structure.
  • Tateaki Wakamiya, Makoto Kamata, Shoichi Kusumoto, Hiroyuki Kobayashi, ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 699-709
    Published: 1998
    Released: August 01, 2005
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    The blood-brain barrier (BBB) is a highly selective membranous barrier regulating the transport of substances in blood into the brain parenchyma. At present, delivery of biologically active peptides or peptide drugs into the brain is quite an important subject from the standpoint of chemotherapy for brain diseases. H–MeTyr–Arg–MeArg–D-Leu–NH(CH2)8NH2 termed 001-C8 was first synthesized to elucidate the structural specificity of peptides for passing through the BBB. The Nα-methylamino acid and D-amino acid residues were appropriately situated in this peptide to protect against the digestion by peptidase. Furthermore, a number of basic peptides were prepared as 001-C8 analogs for studying the relationship between structure and BBB permeability of peptides.
  • Hiroko Kawakami, Yong Zhe Yan, Nobuo Kato, Akira Mori, Hitoshi Takeshi ...
    1998 Volume 71 Issue 3 Pages 711-716
    Published: 1998
    Released: August 01, 2005
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    Azulenequinones gave dimers when they were irradiated with a high-pressure mercury lamp. In polar solvents, head-to-head dimers were predominant, whereas head-to-tail dimers increased in less polar solvents. From 3-methoxy-1,5-azulenequinone, four products were obtained, while bromoazulenequinones and 1,5-azulenequinone gave a single dimer. The product distribution was dependent on the polarity of solvents, substituents, and concentrations.
  • Anatoli Onopchenko, James J. Harrison, Carrie Y. Chan
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 717-721
    Published: 1998
    Released: August 01, 2005
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    A report that phthalic anhydride reacts with diethylenetriamine in acetic acid to form hydrogen phthalate salt of bis(2-phthalimidoethyl)amine predominantly was reinvestigated. The major product that we obtained was bis(2-phthalimidoethyl)amine, some amide, and very little of the salt. With linear triethylenetetramine, we did not obtain N,N′-bis(2-phthalimidoethyl)ethylenediamine, nor the rearranged tris(2-phthalimidoethyl)amine or 1,4-bis(2-phthalimidoethyl)piperazine reported. A novel amide — 2-{N-2-phthalimidoethyl-N-[2-(2-phthalimidoethyl)aminoethyl]carbamoyl}benzoic acid — was formed as the major product instead. The products reported in the literature are attributed to branched and cyclic amines in their triethylenetetramine, and not to rearrangement reactions. Such possibility is supported by analysis of triethylenetetramine from the same supplier (ca. 65% linear), and our failure to duplicate the results with an authentic triethylenetetramine. Several reported compounds were prepared from pure amines, with no evidence of isomerization.
  • Yong-Shou Lin, Akio Yamamoto
    1998 Volume 71 Issue 3 Pages 723-734
    Published: 1998
    Released: August 01, 2005
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    Carbonylation of benzyl alcohol, benzyl formate, dibenzyl ether, and benzyl phenylacetate catalyzed by palladium complexes and promoted by hydrogen iodide gives phenylacetic acid in moderate to excellent yields in aqueous systems. Application of the carbonylation process to other arylmethanol analogs provides convenient means to prepare 2-naphthaleneacetic acid, 3-isochromanone, 1,4-benzenediacetic acid, and o-hydroxybenzeneacetic acid. A mechanism for the catalytic reaction is proposed, which involves (1) formation of benzyl iodide by the reaction of benzyl alcohol with HI in situ, (2) oxidative addition of benzyl iodide to palladium(0) to form a benzylpalladium iodide species, (3) CO insertion into the Pd-benzyl bond to form a (phenylacetyl)palladium iodide species, (4) reductive elimination of phenylacetyl iodide, and (5) its hydrolysis into phenylacetic acid. Evidence supporting the mechanism was obtained by examining the properties of benzyl- and (phenylacetyl)palladium iodide and chloride complexes. Formation of benzyl(carbonyl)palladium species and migratory insertion of the benzyl group to CO was confirmed by means of NMR at low temperature under high pressure.
  • Tadashi Shiraiwa, Masanori Ohkubo, Hideya Miyazaki, Motoki Kubo, Hirok ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 3 Pages 735-739
    Published: 1998
    Released: August 01, 2005
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    The racemic structure of (RS)-bromosuccinic acid [(RS)-BSA] was examined based on the melting-point, solubility, infrared spectrum, and binary and ternary phase diagrams. The results indicated that (RS)-BSA exists as a conglomerate at room temperature, although it forms a racemic compound at the melting point. The optical resolution by preferential crystallization of (RS)-BSA yielded (R)- and (S)-BSA with optical purities of 81—93%. In addition, (RS)-BSA was optically resolved using (1S,2S)-2-amino-1-phenyl-1,3-propanediol as a resolving agent, to yield (R)- and (S)-BSA with optical purities of 99 and 83%, respectively. The obtained (R)- and (S)-BSA were recrystallized from water to obtain optically pure BSA enantiomers.
  • Masato Nanjo, Akira Sekiguchi, Hideki Sakurai
    1998 Volume 71 Issue 3 Pages 741-747
    Published: 1998
    Released: August 01, 2005
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    Lithiopentamethyldisilane (LiSiMe2SiMe3, 1a), two isomer of lithioheptamethyltrisilane (LiSiMe2SiMe2SiMe3, 1b; LiSi(SiMe3)2Me, 1c), lithio[tris(trimethylsilyl)]silane (LiSi(SiMe3)3, 1d), 2-lithio-1,3-diphenylpentamethyltrisilane (LiSi(SiMe2Ph)2Me, 1e), 2-lithio-2-phenylhexamethyltrisilane (LiSi(SiMe3)2Ph, 1f), 3-lithio-1,5-diphenylnonamethylpentasilane (LiSi(SiMe2SiMe2Ph)2Me, 1g), lithio[bis(dimethlphenylgermyl)]methylsilane (LiSi(GeMe2Ph)2Me, 1h), and lithiotrimethylsilane (LiSiMe3, 3) were prepared by lithium–mercury exchange reactions. The unsolvated lithiosilanes exist as the aggregated oligomers in non-polar solvents, whereas those solvated by THF or Et2O exist as monomers. Synthesis and detailed spectroscopic studies of the lithiosilanes with Si–Si bonds are reported.
  • Michinori Oki, Hiroshi Ikeda, Shinji Toyota
    1998 Volume 71 Issue 3 Pages 749-754
    Published: 1998
    Released: August 01, 2005
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    Solvolyses of 2-bromoadamantane in aqueous alcohols were carried out to find the selectivities, kether/kalcohol, at various concentrations of water in an alcohol and at various temperatures. While the observed ratios contain a large error or fluctuate at low concentrations of water, they were almost constant for 1.0 : 0.8 alcohol/water mixtures. The selectivity was also independent of temperatures of the reaction. The significance of the selectivity, which is determined by the ease of solvent intervention into contact ion pairs, is discussed. D values, which are obtained by taking reciprocals of the selectivity for the 1.0 : 0.8 mixture, are proposed as a measure of the dimensiosolvatic effects when a solvent molecule intervenes into the contact ion pair.
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