Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 73 , Issue 3
Showing 1-33 articles out of 33 articles from the selected issue
  • Isao Tsuyumoto, Tsuguo Sawada
    2000 Volume 73 Issue 3 Pages 507-514
    Published: 2000
    Released: October 31, 2001
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    Recent studies on ultrafast energy transfer at solid/liquid interfaces were reviewed, focusing on our developed photothermal techniques: femtosecond transient reflectivity (fs-TR) method, femtosecond transient reflecting grating (fs-TRG) method, and picosecond surface plasmon resonance transient reflecting grating (ps-SPR-TRG) method. Firstly, Pt/auqoues electrolyte interfaces were measured using the fs-TR method. An ultrafast relaxation component of 20 fs was first observed in the Pt/HCl (aq) and Pt/H2SO4 (aq) interfaces, in which the anions (Cl- and SO42-) have strong affinity to the Pt surface. It was suggested that this is due to the scattering of non-thermalized electrons by adsorbed anions. Secondly, TiO2/KSCN (aq) interfaces were measured using the fs-TRG method. Ultrafast relaxation components (110—690 fs) were observed in the TRG signals. This marked the first observation of the contribution of nonequilibrium holes to the energy transfer at TiO2/KSCN (aq) interfaces. Thirdly, Au/NaCl (aq) interfaces were measured using ps-SPR-TRG method, focusing at both the behavior of hot electrons and thermal diffusion. The results indicated that an ultrafast energy transfer process occurs prior to the heat diffusion and this process is hindered by the adsorbed ions.
  • Reizo Kato
    2000 Volume 73 Issue 3 Pages 515-534
    Published: 2000
    Released: October 31, 2001
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    Structural and physical properties of the Cu salts of a series of π-acceptors N,N-dicyanobenzoquinonediimines (DCNQIs) are described. The most notable feature of this system is that 3d electrons in Cu interact with pπ electrons in DCNQI near the Fermi level. This unique feature has provided a lot of interesting solid state properties: the Mott transition triggered by the Peierls transition, the pressure-induced metal-insulator transition, the metal-insulator-metal (reentrant) transition, the three-dimensional Fermi surface, the anomalous isotope effects, the antiferromagnetic transition, the weak ferromagnetism, and the electron mass enhancement. The aim of this account is to give an overview of this unique pπ-d system.
  • Katsuya Ishiguro, Yasuhiko Sawaki
    2000 Volume 73 Issue 3 Pages 535-552
    Published: 2000
    Released: October 31, 2001
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    The structure and chemical properties of 1,3-dipolar peroxidic species (X+-O-O-) such as ozone (X = O), nitroso oxides or nitrenium peroxides (X = RN), carbonyl oxides or carbenium peroxides (X = R2C), and persulfoxides or sulfonium peroxides (X = R2S) have been attracting much attention from synthetic, biological, and theoretical standpoints. These active oxygen species can be classified into two types depending on whether the X+ is an enium (carbenium, nitrenium, silylenium etc.) ion or an onium (ammonium, oxonium, phosphonium, sulfonium etc.) ion, and their reactivities are quite different depending on the nature of X. The individual features as well as the overviews of structure and reactivities of these X-O-O species are reviewed. Ozone and nitroso oxides have an electrophilic character while carbonyl oxides usually act as a nucleophilic oxygen transfer agent, their reactivities being controlled by substituents. It is important to see whether or not XOO species can isomerize to the cyclic isomers. Although cyclic O3 is thermodynamically unstable, dioxiranes, the cyclic form of carbonyl oxides, have been isolated and fully characterized. It has been suggested that nitroso oxides isomerize to the cyclic form yielding the corresponding nitro compounds unimolecularly. In the case of persulfoxides (X = R2S), the dipolar structure (X+-O-O-) is important, their characteristic reaction being nucleophilic O-transfer to sulfoxides, while 3λ5-dioxaphosphirane (X = R3P) can exist only in the cyclic form, showing electrophilic reactivity. Effects of X's on structure and reactivity of these oxides were systematically examined by the density functional BLYP/6-31G* calculations. The inductive effect through σ-framework has been found to dominate the thermodynamic stabilities of carbonyl oxides, while the π-donating property of substituents governs the activation energy for the cyclization to dioxiranes.
  • Biswajit Pal, Kalyan Kali Sen Gupta
    2000 Volume 73 Issue 3 Pages 553-560
    Published: 2000
    Released: October 31, 2001
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    The kinetics of hexachloroplatinate(IV) reduction by some neutralized α-hydroxy acids such as glycolic, lactic, α-hydroxyisobutyric, mandelic, atrolactic, and benzilic acids in a carbonate-hydrogencarbonate buffer medium have been investigated. Platinum(IV) is reduced by the substrates to platinum(II) in a one-step two-electron process, whereas the substrates are oxidized to give formaldehyde, acetaldehyde, acetone, benzaldehyde, acetophenone, and benzophenone for the respective reactions. The pseudo-first-order rate constant is independent of the initial [platinum(IV)] as well as [OH-]. The reaction rate increases with increasing [substrate], but decreases with increasing chloride concentration. The reactions obey the following rate expression:

    −d[PtIV]t/dt=(kKe[A][PtIV]t )/([Cl]+Ke[A])·

    The reactions proceed through an initial 1 : 1 complex formation between the reactants, followed by decomposition of the complex to give the respective reaction products via C-C bond cleavage. The reactivity of the α-hydroxycarboxylate towards Pt(IV) are as follows: atrolactic acid > mandelic acid > benzilic acid > α–hydroxyisobutyric acid > lactic acid > glycolic acid. Thermodynamic parameters for the decomposition step have been evaluated. The mechanism of the reactions is discussed.

  • Fawzi Hassan Assaf
    2000 Volume 73 Issue 3 Pages 561-568
    Published: 2000
    Released: October 31, 2001
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    The effect of chloride ions on both anodic dissolution and pitting corrosion of tin metal in the aerated equimolar solutions 0.1 M (1 M = 1 mol dm-3) citrate-chlorid-oxo-anions (CrO42-, WO42-, and MoO42-) has been investigated. Different techniques were used, such as potentiodynamic, potentiostatic polarization, electrochemical impedance spectroscopy techniques. These were complemented by surface examination using scanning electron microscopy. Lower current values in the presence of equimolar (0.1 M) citrate-oxo-anions with addition of Cl- in various concentrations were observed, compared with those obtained in the oxo-anion free solutions. Thus, these oxo-anions might create a certain impediment or barrier to the attack of the aggressive Cl- on the metal surface. However, the addition of the studied anions at lower concentrations (10-3 and 10-2 M) in 0.1 mol dm-3 citrate-chloride, enhanced the active metal dissolution and passivity break down of tin. Retardation to a considerable extent was observed, however, at higher concentrations (5×10-2 and 10-1 M). All measurements using the different techniques, under the same conditions, confirmed that the order of reduced aggressiveness of Cl- was CrO42- > WO42- > MoO42-. This indicates that CrO42- remains the best inhibitor to prevent the pitting corrosion, probably through its ability to repair defects in the oxide film.
  • Toshiki Sugai, Hisanori Shinohara
    2000 Volume 73 Issue 3 Pages 569-573
    Published: 2000
    Released: October 31, 2001
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    Multiple metal-rich ion alkali halide clusters from solid crystals of NaF and CsI have been produced and characterized for the first time by a newly developed high-pressure laser-vaporization cluster source. The observed positive metal-rich clusters are NanFm+ (n ≈ 40, n-m = 1—9) and CsnIm+ (n ≈ 60, n-m = 0—5), which have enhanced intensities at n = 14, being independent of m, indicating the existence of multiple excess electrons. For negative clusters, NanFm- (n ≈ 40, n-m = -1—10) and CsnIm- (n ≈ 60, n-m = -2—3) have been observed. The NaF metal-rich negative clusters show two types of distinct magic numbers at n-m = 7 ((NaF)mNa7-) and n = 14 (Na14F13-x-, x = 0—4). The former and latter magic-number ions suggest the existence of a negative core ion of Na7- and a cubic 3×3×3 structure with multiple excess electrons, respectively. The present high-pressure laser-vaporization cluster source is suitable to produce these unstable clusters with a unique stoichiometry.
  • Isao Ono, Tetsuo Ikegami, Tomoko Inayoshi
    2000 Volume 73 Issue 3 Pages 575-581
    Published: 2000
    Released: October 31, 2001
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    The photochemistry of three types of 2-(alklylcarbamoyl)quinolines was studied. The illumination of 2-(diethylcarbamoyl)quinolines (1a, 1b, and 1c) afforded 2-(2-ethylaminopropionyl)quinolines (3a, 3b, and 3c) with a small amount of five-membered cyclic products, 1H-pyrrolo[3,4-b]quinolin-3(2H)-ones (4a, 4b, and 4c), both of which were formed via Type-II hydrogen-atom abstraction from the T1 state. 2-(Ethylcarbamoyl)quinoline (1d) did not undertake any photochemical change. The photochemical inactivity of 1d could be attributed to the unfavorable orientation of its carbamoyl substituent for intramolecular hydrogen-atom abstraction by a ring nitrogen. The illumination of 2-(alkylcarbamoyl)-3-methyl quinolines (2a and 2b) afforded 2-(N-acetyl-N-alkylcarbamoyl)-3-methyl quinolines (5a and 5b), which were suggested to be formed by the atmospheric oxidation of an unstable photoproduct formed via the S1 state.
  • Kohjiro Hara, Kazuhiro Sayama, Hironori Arakawa
    2000 Volume 73 Issue 3 Pages 583-587
    Published: 2000
    Released: October 31, 2001
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    3-Thiopheneacetic acid (3TA) was electrochemically oxidized and polymerized on indium tin oxide (ITO) electrodes in a 0.05 mol dm-3 tetrabutylammonium perchlorate (TBAP) acetonitrile solution; also, the photoelectrochemical properties of the resulting poly(3-thiopheneacetic acid) (P3TA) were studied. The film showed n-type semiconductor properties, although anion-doped conducting polymer prepared by electrochemical oxidation is generally of the p-type. An anodic photocurrent due to oxygen evolution from water was observed under white-light irradiation in a 0.1 mol dm-3 Na2SO4 aqueous solution. The anodic photocurrent density at 1.9 V vs. Ag/AgCl was 1.1 mA cm-2 and the flat-band potential of P3TA, estimated from the onset of an anodic photocurrent, was -0.1 V vs. Ag/AgCl. The band gap of P3TA was 2.4 eV, obtained from an vs. ( PC)1/2 plot.
  • Isao Suzuki, Yasuyuki Tsuboi, Hiroshi Miyasaka, Akira Itaya
    2000 Volume 73 Issue 3 Pages 589-598
    Published: 2000
    Released: October 31, 2001
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    Using a picosecond laser photolysis system, the absorption spectra of excited states of C60 in twelve solvents were measured in the 590—1190 nm wavelength range. The absorption spectra observed immediately after a 532 nm picosecond laser excitation and those in the late-time region depended upon the solvents. In particular, the former dependence was much larger than the latter one. Their spectral shapes did not correlate with either dielectric constant of the solvents or their refractive index, but with their ionization potential (Ip). The early-gated absorption spectra of C60 in solvents with a small Ip were extraordinary broad compared with those in solvents with a large Ip. In addition, the absorption changed to those observed in the late-time region both with a decay time constant of 1.2±0.05 ns and with keeping the isosbestic points. This time constant was the same as the lifetime of the C60-singlet excited state (1C60*) reported previously, and the presence of the isosbestic points was also the same as that observed during spectral evolution from Sn←S1 absorption of C60 to its Tn←T1 one. Combining the results of the resonance Raman spectra by Gallagher et al. with the present ones suggested that the solvent-dependent early-gated absorption spectra of the C60-excited state are ascribed to 1C60* with a distortion induced by specific interactions with solvents molecules through the donation of their π-electron density without forming obviously excited-state complexes. The transient absorption spectra observed immediately after the direct excitation of ground-state charge-transfer complexes formed between C60 and solvent molecules with a small Ip were not due to ionic species, but to 1C60*, suggesting that the photogenerated ionic species undergo a very rapid charge-recombination reaction to result in 1C60* and the ground-state solvent molecule. The absorption spectra in the late-time region, which showed a slight dependence on Ip of the solvent molecules, as aforementioned, were assigned to the Tn←T1 absorption of C60; the dependence was considered to be also ascribed to the same reason as that for 1C60*.
  • Kotohiro Nomura, Warit Sidokmai, Yukio Imanishi
    2000 Volume 73 Issue 3 Pages 599-605
    Published: 2000
    Released: October 31, 2001
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    RuX2(ethylene)(pybox) [X = Cl (1), I (2), and CF3SO3 (3); pybox = 2,6-bis[(4S)-4-isopropyl-2-oxazolin-2-yl]pyridine] complexes have exhibited moderate catalytic activity for ethylene homopolymerization and ethylene/1-hexene copolymerization in the presence of MAO. The incorporation of 1-hexene (27.2 mol%) in the resultant copolymer was confirmed by 13C NMR spectrum. The resonances corresponding to the triad sequence of HHH were negligible. A small rE·rH value of 0.32, where rE and rH are the monomer reactivity ratios of ethylene and 1-hexene, respectively, was thus obtained, indicating a significantly alternating tendency. FeCl2(pybox) (4) has also exhibited the activity for ethylene polymerization in the presence of MAO. The attempted copolymerization of ethylene with 1-hexene by 4 gave linear polyethylene without incorporating 1-hexene.
  • Kiyoshi Tsuge, Masato Kurihara, Koji Tanaka
    2000 Volume 73 Issue 3 Pages 607-614
    Published: 2000
    Released: October 31, 2001
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    A ruthenium aqua complex having a quinone ligand, [Ru(trpy)(dbq)(H2O)](ClO4)2 (trpy = 2,2:6,2′′-terpyridine, dbq = 3,5-di-t-butyl-1,2-benzoquinone) ([Ru(q)(H2O)](ClO4)2) was prepared. Its electrochemical properties and electronic absorption spectra were measured in the presence of a base in acetone. The detailed analysis of those measurements revealed that the addition of a base caused not only the deprotonation but also the reduction of [Ru(q)(H2O)]2+. The redox reactions coupled with acid-base reactions were demonstrated from the large difference in redox properties of aqua and hydroxo complexes. Taking advantage of unique redox reactions induced by the acid-base equilibrium between aqua and hydroxo complexes, we have succeeded in constructing the first energy transducer which converts the proton gradient to electricity. A similar ruthenium aqua complex with a bipyridine ligand, [Ru(trpy)(bpy)(H2O)](ClO4)2, also reversibly dissociates a proton of aqua ligand. However, it has no ability to convert the proton gradient to electricity due to the lack of a suitable molecular orbital which can accommodate electrons on the electron-rich hydroxo ligand.
  • Kyue-Hyung Lee, Mitsuko Oshima, Toshio Takayanagi, Shoji Motomizu
    2000 Volume 73 Issue 3 Pages 615-622
    Published: 2000
    Released: October 31, 2001
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    The amounts of lanthanoids (Ln) and yttrium (Y) in eleven GSJ (Geological Survey of Japan, Tsukuba) rock reference materials have been determined. Fundamental studies on trace analysis of rock samples by inductively coupled plasma-mass spectrometry (ICP-MS) were conducted to obtain accurate contents of rare earth elements. The samples were dissolved using a conventional acid digestion technique, then treated on a cation exchange column for the removal of matrix components. Isobaric interferences from metal oxide ions were corrected based on the results of the experimentally obtained percentages of the metal oxide formation. A long-term stability test of the ICP-MS instrument with multielement standard solutions proved that all data obtained at concentration ranges from 0.01 to 10 ng ml-1 were reproducible, the drift of signals were less and the relative standard deviation (RSD) was within ±2.5%. The recoveries of Ln and Y from the cation exchange column were found to be (100±4)%. The results obtained for an igneous rock series showed good agreement with the recommended values given by GSJ, and their chondrite-normalized patterns were smooth.
  • Hirochika Naganawa, Hideya Suzuki, Shoichi Tachimori, Akinobu Nasu, Ta ...
    2000 Volume 73 Issue 3 Pages 623-630
    Published: 2000
    Released: October 31, 2001
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    The effect of the picrate (pic-) ion on Eu(III) extraction with a diamide (da) from aqueous nitric acid (0.001—0.1 mol dm-3) solutions into benzene was clarified on the basis of the stoichiometry of ion-pair extractions by analyzing the distribution data of Eu(III) and picric acid (Hpic). The extraction of Eu(III) with da was extremely enhanced by adding a hydrophobic anion of pic- to the liquid-liquid system. From analyses of the distribution data of Eu(III) and Hpic, it was concluded that the effect of the hydrophobic anion was caused by the extraction of a single ion-pair of [Eu(da)2](pic)3. The nitrate ion had no relation with the cooperative effect of da and pic-, i.e., the extraction of [Eu(da)2](NO3)3, [Eu(da)2](pic)(NO3)2, and [Eu(da)2](pic)2(NO3) was practically negligible as against the [Eu(da)2](pic)3 extraction. The cooperative effect was reduced by an increase in the aqueous HNO3 concentration, which was induced by a decrease in the pic- concentration in the aqueous phase; the dissociation of Hpic into pic- ion was suppressed by an increase in the H+ concentration, and a part of molecular Hpic was extracted into the organic phase. Furthermore, the extraction of Hpic was also enhanced by an increase in the da concentration in the organic phase, which also induced a decrease in the aqueous pic- concentration. This was found to be due to the formation of a 1 : 1 complex between da and Hpic. However, the extraction of the complexes between da and HNO3 was negligible in the acid concentration range in the present study.
  • Hidetake Seino, Yasushi Mizobe, Masanobu Hidai
    2000 Volume 73 Issue 3 Pages 631-639
    Published: 2000
    Released: October 31, 2001
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    Tungsten pyrrolylimido and diazoalkane complexes, cis,mer-[WCl2(NNC4H4)(PMe2Ph)3] and cis,mer-[WCl2(NN=CRR)(PMe2Ph)3], which are readily derived from the dinitrogen complex cis-[W(N2)2(PMe2Ph)4], reacted with [PPh4]2[WS4] to give the sulfide-bridged di- or trinuclear pyrrolylimido and diazoalkane complexes, [PPh4][WCl(NNC4H4)(PMe2Ph)2(μ-S)2WS2] (4) and [PPh4][WCl(NN=CRR)(PMe2Ph)2(μ-S)2WS2] (R = R = Me (5a); R = Me, R = Ph; R = H, R = p-MeC6H4), or [{WCl(NNC4H4)(PMe2Ph)2(μ-S)2}2W] (7) and [{WCl(NN=CMePh)(PMe2Ph)2(μ-S)2}2W]. Treatment of 4 or 5a with tetraalkylthiuram disulfide resulted in the formation of sulfide-dithiocarbamate complexes: [W(NNC4H4)(PMe2Ph)(S2CNR2)(μ-S)2WS(S2CNR2)] (R = Et, Pri (9b)) and [W(NN=CMe2)(PMe2Ph)(S2CNEt2)(μ-S)2WS(S2CNEt2)]. On the other hand, replacement of two PMe2Ph ligands in 4 and 5 by Ph2PCH2CH2PPh2 (dppe) afforded [PPh4][WCl(NNC4H4)(dppe)(μ-S)2WS2] and [PPh4][WCl(NN=CRR)(dppe)(μ-S)2WS2] (R = R = Me; R = Me, R = Ph (12b)), where 12b has been shown to react further with [RhCl(cod)]2 (cod = 1,5-cyclooctadiene) to give a bimetallic trinuclear complex [WCl(NN=CMePh)(dppe)(μ-S)2W(μ-S)2Rh(cod)] (13). Detailed structures have been determined by X-ray analyses for 4, 5a, 7, 9b, and 13.
  • Eri Ishikawa, Toshihiro Yamase
    2000 Volume 73 Issue 3 Pages 641-649
    Published: 2000
    Released: October 31, 2001
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    The photoreduction processes of α-[PMo12O40]3- (α-PMo12(0)) in aqueous solutions at pH 2.0 are discussed on the basis of the results of the electrical conductivities and 31P NMR spectra of photolytes, and the crystal structures of α-type two-electron and β-type four-electron reduction species isolated from photolytes as α-[(iPr)2NH2]4[HPMo12O40]·4H2O (1) (α-PMo12(II)) and β-[(iPr)2NH2]3[H4PMo12O40]·2H2O (2) (β-PMo12(IV)) : (i) A one-electron reduction species produced by the photoredox reaction of α-PMo12(0) with methanol is degraded to α-B-[H3PMo9O31(OH)3]3- (α-B-PMo9(0)) and MoV-containing Mo-triad species (Mo3). (ii) The formation of the α-type mono-protonated two-electron reduction species, α-[HPMo12O40]4- (α-PMo12(II)), results from the isomerization of the β-type two-electron reduction species, β-[PMo12O40]5- (β-PMo12(II)), which is produced by coupling between the one-electron reduced α-B-PMo9 (α-B-PMo9(I)) and Mo3. (iii) The β-type four-protonated four-electron reduction species, β-[H4PMo12O40]3- (β-PMo12(IV)) as a final product is produced by the disproportionation of α-PMo12(II). The change in the electrical conductivity of the photolytes during photolysis supports the above processes for the photoreduction of α-[PMo12O40]3- to β-[H4PMo12O40]3- at pH 2.0.
  • Kunihisa Sugimoto, Takayoshi Kuroda-Sowa, Tamotsu Goto, Masahiko Maeka ...
    2000 Volume 73 Issue 3 Pages 651-655
    Published: 2000
    Released: October 31, 2001
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    Two triangular tripalladium compounds, [Pd3(μ3-Cl)2(HqnS)6]Cl2 (1) (HqnS = quinoline–2(1H)–thione), and [Pd3(μ3-Cl)2(Et2dtc)2(PPh3)2]·C6H6 (2) (Et2dtc = N, N-diethyldithiocarbamate anion), were prepared. Their single crystal X-ray structure analyses revealed they have a similar trigonal bipyramidal framework of Pd3(μ3-Cl)2 with two chlorine atoms in apical positions. Each Pd atom in all clusters has two additional coordination sites to establish a square planar cis-PdL2(μ3-Cl)2 geometry. In compound 1, six sulfur atoms of six HqnS ligands with thion form are coordinated to the vacant sites of the Pd3(μ3-Cl)2 core. Two coordination sites of one of the three Pd atoms in 2 are occupied by two triphenylphosphines and those of the other two are coordinated by two S atoms of Et2dtc. Although both compounds have 50 valence electrons, only 1 shows paramagnetic behavior. Crystallographic data are as follows. 1: Pd3Cl4S6N6C54H42, triclinic, P1- a = 14.988(5), b = 17.328(3), c = 12.642(1) Å, α = 93.61(1), β = 96.06(2), γ = 71.79(2)°, V = 3099(1) Å3, and Z = 2. 2: Pd3Cl2P2S4N2C52H56, monoclinic, P21, a = 12.278(5), b = 17.426(6), c = 12.630(3) Å, β = 94.65(3)°, V = 2693(2) Å3, and Z = 2.
  • Takashi Kawamura, Hisanori Kachi, Hiroshi Fujii, Chihiro Kachi-Terajim ...
    2000 Volume 73 Issue 3 Pages 657-668
    Published: 2000
    Released: October 31, 2001
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    The odd electron in the δRhRh* orbital of (3,1)-[Rh2(mhq)4py]+ (1+; Hmhq = 4-methyl-2-quinolinol) was estimated to be delocalized onto each π system of the four mhq bridges to the extent of ca. 9% based on its 1H NMR paramagnetic shifts. The experimental spin distribution in the mhq ligands is consistent with a model of mixing of the π HOMOs of the mhq ligands into the δRhRh* singly occupied molecular orbital (SOMO). In crystals of (3,1)-[Rh2(hq)4py] (2; Hhq = 2-quinolinol) and its cationic radical salts, 2 or 2+ molecules form intermolecular π-stack arrangements of hq ligands. Intermolecular interaction between 2+ molecules in crystal was studied by examining electronic spectra, magnetic susceptibility, ESR, and electrical conductance of its salts.
  • Toshio Takayanagi, Noriaki Ban, Eiko Wada, Mitsuko Oshima, Shoji Motom ...
    2000 Volume 73 Issue 3 Pages 669-673
    Published: 2000
    Released: October 31, 2001
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    Ion association reactions between monovalent polycyclic aromatic cations and anions have been studied through the mobility change in capillary zone electrophoresis. When the cationic reagent possessing aromatic moieties was used, isomers of aromatic anions were well resolved. Apparent electrophoretic mobility of the anions decreased with an increase in the concentration of the cationic reagent in the migrating solution; the magnitude of the decrease was large when bulkier cations were used. The ion association constants obtained by analyzing the mobility change increased with an increase in the number of aromatic rings of either the pairing cations or the anions. The ion associates formed consist of monovalent cations and anions, and the ion association constant for an ion associate formed between 1-propylbenzo[f]quinolinium ion and pyrene-1-carboxylate ion was in the magnitude of 102.74 dm3 mol-1. Such ion associability was interpreted from the contribution of the stacking of aromatic moieties in an aqueous solution, in addition to the increase in the hydrophobicity.
  • Nasser Iranpoor, Hadi Adibi
    2000 Volume 73 Issue 3 Pages 675-680
    Published: 2000
    Released: October 31, 2001
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    Iron(III) trifluoroacetate was used as an efficient and nonhygroscopic catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides. The addition of chloride, bromide, iodide, and nitrate ions to epoxides to produce the corresponding 2-halo and 2-nitratoalkanols and also the conversion of epoxides to acetonides and thiiranes were also performed efficiently in the presence of this catalyst.
  • Shuji Kanemasa, Kenji Adachi, Hidetoshi Yamamoto, Eiji Wada
    2000 Volume 73 Issue 3 Pages 681-687
    Published: 2000
    Released: October 31, 2001
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    Enantiopure 2-amino-3,3-diphenyl-1-propanol has been synthesized by the hidantoin route starting from diphenylacetaldehyde, followed by subsequent functional group transformations and optical resolution by a chiral HPLC. This amino alcohol can be converted into two new chiral ligands: 4,4-bis(diphenylmethyl)-2,2-bioxazoline and 2,2-isopropylidenebis(4-diphenylmethyloxazoline), and further to complexes with copper(II) trifluoromethanesulfonate and nickel(II) perchlorate hexahydrate. The nickel(II) aqua complex derived from the bisoxazoline effectively catalyzes the Diels-Alder reactions of cyclopentadiene with 3-acryloyl-2-oxazolidinone in high endo-selectivities and moderate enantioselectivities through a square planar transition structure.
  • Norikazu Miyoshi, Mami Nishio, Shunsuke Murakami, Tomohiro Fukuma, Mak ...
    2000 Volume 73 Issue 3 Pages 689-692
    Published: 2000
    Released: October 31, 2001
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    A convenient one pot allylation of aldehydes with allylic iodides prepared in situ from allylic alcohols by using trimethylsilyl chloride and sodium iodide proceeds smoothly in the presence of metallic bismuth to afford the corresponding homoallylic alcohols in good yields.
  • Masaaki Iwata
    2000 Volume 73 Issue 3 Pages 693-704
    Published: 2000
    Released: October 31, 2001
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    We designed ``multi-layer macromonocyclic polyamines'' which might be appropriate polymorphismic molecular scaffolds as host-molecules in ionic or molecular interaction with small or large guest ions or molecules. In polymorphismic molecules, several macromonocyclic polyamines with the same and/or different ring sizes and nitrogen contents are connected to each other by alkylene spacers with various length of the chain. Actual target molecules are characterized by possessing methylene chain arrays of natural polyamines, and we have synthesized from simple starting materials fourteen component macromonocycles with various sizes, 12- to 34-membered rings containing three to eight nitrogen atoms, as essential building blocks required for construction of multi-layer molecules. Our method of synthesis was shown to be very efficient. In a final step, the N-protecting benzyl group was successfully removed by hydrogenation on 10%-Pd/C under 4 kg cm-2 H2 to give the cyclic amine precursors, which could be internal and terminal components in the architecture of the multi-layer molecules. The structures of synthesized compounds were characterized and confirmed by EA, 1H NMR, SIMS, and FAB(+) mass spectrometry.
  • Masashi Sugiya, Hiroyuki Nohira
    2000 Volume 73 Issue 3 Pages 705-712
    Published: 2000
    Released: October 31, 2001
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    Optically pure bisphosphine oxides were conveniently synthesized by Kolbe electrolytic coupling reaction of carboxylic acids possessing a chiral phosphinoyl group in 60—65% isolated yield. This synthetic approach provides a variety of accesses to P-chiral bisphosphine ligands. Their absolute configurations were intercorrelated with that of the previous reported BisP*-borane. Asymmetric hydrogenation of α-(acylamino)acrylic acids by a rhodium complex with BisP* (R = t-octyl or 1,1,3,3-tetramethylbutyl) affords N-acylamino acids in 94—96% ee.
  • Takeshi Iwasaki, Nobuhiro Kihara, Takeshi Endo
    2000 Volume 73 Issue 3 Pages 713-719
    Published: 2000
    Released: October 31, 2001
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    Various oxiranes reacted with carbon dioxide at 100 °C using lithium bromide as a catalyst under atmospheric pressure to afford the corresponding five-membered cyclic carbonates quantitatively. The rate of the reaction increased as the bulkiness of substituents on the oxirane ring was reduced or an electron-withdrawing group was introduced on the oxirane ring. The stereochemistry of the reaction of oxirane and carbon dioxide was retention without loss of optical purity. When substituted phenylethylene carbonates were reacted with benzylamine, the selectivity to afford secondary alcohol increased as the electron-withdrawing ability of the para-substituent increased.
  • Shunji Ito, Miwako Fujita, Noboru Morita, Toyonobu Asao
    2000 Volume 73 Issue 3 Pages 721-727
    Published: 2000
    Released: October 31, 2001
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    Acid-catalyzed condensations of 1-methyl and 1,6-di-t-butylazulenes with 9-anthracenecarbaldehyde led us to unexpected 9-(1-azulenyl)-10-[(1-azulenyl)methylidene]-9,10-dihydroanthracenes 10a and 10b as major products, together with (9-anthryl)di(1-azulenyl)methanes 7a and 7b. Hydride abstraction from 7a, 7b, and 10b with DDQ afforded substituted (9-anthryl)di(1-azulenyl)methyl and (1-azulenyl)[10-(1-azulenyl)-9-anthryl]methyl hexafluorophosphates 6a, 6b·PF6- and 11b·PF6-, respectively. Their properties were fully characterized. The reaction of the 3-methyl derivatives 10a, however, did not afford the desired (3-methyl-1-azulenyl)[10-(3-methyl-1-azulenyl)-9-anthryl]methyl hexafluorophosphate (11a·PF6-), due to the low stabilities of 11a. While cations 6a and 6b prepared from 7a and 7b showed high stabilities with large pKR+ values (10.7±0.1 and 12.4±0.1, respectively), cation 11b exhibited relatively low stabilities with the pKR+ value of 5.0±0.1.
  • Akihiko Ishii, Takenori Omata, Kazuyo Umezawa, Juzo Nakayama
    2000 Volume 73 Issue 3 Pages 729-737
    Published: 2000
    Released: October 31, 2001
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    2,2,4,4-Tetramethyl-1-phenyl-6,7-dithiabicyclo[3.1.1]heptane was treated with 2KHSO5·KHSO4·K2SO4 to yield cis- and trans-3,6-bis(1,1,3,3-tetramethyl-4-oxo-4-phenylbutyl)-1,2,4,5-tetrathianes. The formation mechanism of the tetrathianes is discussed. X-Ray crystallography disclosed that the cis- and trans-isomers take twist and chair conformations, respectively, in the solid state. Variable-temperature 1H NMR spectroscopy in solution showed that the cis-isomer takes a twist conformation exclusively in the temperature range, whereas the trans-isomer exists as an equilibrium mixture of chair and twist conformers. The cis-tetrathiane reacted with Lawesson's reagent at 50 °C to give the corresponding di-2-thianyl disulfide.
  • Takashi Mukawa, Jun Muraoka, Shinsaku Shiraishi
    2000 Volume 73 Issue 3 Pages 739-743
    Published: 2000
    Released: October 31, 2001
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    The 1,3-dipolar cycloadducts of aromatic nitrile oxides with 2,5- and 2,6-dialkyl-p-benzoquinones were treated with acetic anhydride/sulfuric acid to give isoxazole-fused hydroquinone diacetates in good yields. The base-induced rearrangement products from some of the 1,3-dipolar cycloadducts were treated with acetic anhydride/sulfuric acid to afford isoxazole-fused catechol diacetates and/or isoxazole-fused hydroquinone diacetates, depending on the slight difference in the substituents of the base-induced rearrangement products. The differences in the products are interpreted in terms of steric hindrance around the carbonyl and hydroxy moieties of the base-induced rearrangement products.
  • Nobuhiro Takano, Chigusa Seki, Isao Shimono, Takanori Kobayashi, Takao ...
    2000 Volume 73 Issue 3 Pages 745-746
    Published: 2000
    Released: October 31, 2001
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    Poly[N-(5-carboxyhexyl)pyrrole] coated carbon-fiber electrodes incorporating palladium metal were prepared for the electrocatalytic hydrogenation of methyl α-oxobenzeneacetate, 2-cyclohexen-1-one, and diphenylacetylene in an ethanol-buffer solution. The reactions using these electrodes proceeded smoothly to give hydrogenated products in good yields.
  • Tingli Ma, Takahiko Kojima, Yoshihisa Matsuda
    2000 Volume 73 Issue 3 Pages 747-748
    Published: 2000
    Released: October 31, 2001
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    4,5-Disubstituted catechols were prepared in high yields via successive Friedel-Crafts acylation in the presence of a Ti(IV) catalyst or I2 and reduction with triethylsilane of veratroles. This method provides an effective and well-regulated synthetic strategy toward catechol derivatives having a variety of substituents at the 4- and 5- positions.
  • Kazunori Hirabayashi, Tatsuhiro Kondo, Fumihiko Toriyama, Yasushi Nish ...
    2000 Volume 73 Issue 3 Pages 749-750
    Published: 2000
    Released: October 31, 2001
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    The Mizoroki-Heck type reaction of methyl(phenyl)(3,3,3-trifluoropropyl)silanol (1a) with ethyl acrylate in the presence of Pd(OAc)2 (10 mol%) and Cu(OAc)2/LiOAc gave ethyl cinnamate in 70% yield. The palladium-catalyzed cross-coupling of 1a with 4-iodomethoxybenzene in the presence of Ag2O also afforded 4-methoxybiphenyl in 51% yield.
  • Ping Lu, Naoki Toshima
    2000 Volume 73 Issue 3 Pages 751-758
    Published: 2000
    Released: October 31, 2001
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    Poly(N-vinyl-2-pyrrolidone)-protected Ni/Pd bimetallic colloidal nanoparticles, prepared by the polyol reduction method, have been proved to have a nanometer-sized alloy structure with both metals at zerovalent state by our previous study of TEM, XRD, EXAFS, and XPS analyses. Here, dispersions of these bimetallic nanoclusters with different composition ratios are extensively examined as catalysts for the hydrogenation of various nitrobenzene derivatives: i.e., p-nitrotoluene, p-nitroanisole, 1-nitronaphthalene, p-nitrobenzonitrile, and methyl p-nitrobenzoate, at 30 °C under an atmospheric pressure of hydrogen. These bimetallic nanoclusters exhibit excellent catalytic properties for the reduction of a nitro group to an amino group with high selectivity. The catalytic activity strongly depends on the metal composition of the particles. The maximum catalytic activity can be observed at a certain intermediate composition ratio, being 3—4 times greater than that of a monometallic colloidal Pd catalyst. A bimetallic nanocluster with the mole ratio of Ni : Pd = 1/4 was the most active catalyst for the hydrogenation of para-substituted nitrobenzenes. An approximately linear relationship exists between the hydrogenation rate of the substrate with an electron-donating or electron-withdrawing group and the corresponding Hammett constant of the substituent, as well as between the hydrogenation rate and the LUMO energy level of the substrate.
  • Junya Kobayashi, Takashi Shimizu
    2000 Volume 73 Issue 3 Pages 759-763
    Published: 2000
    Released: October 31, 2001
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    This paper discusses the promotion of isobutane dehydrogenation due to sulfur species adsorbed on Pt-alkali metal (Li, Na, or K)/Al2O3 catalysts. A treatment with hydrogen sulfide at 833 K increased the selectivity to isobutene on all Pt-alkali metal/Al2O3 catalysts. The promotion effect of sulfurization was most significant on a Pt (1 wt%)-Na2O (3 wt%)/Al2O3 catalyst; the selectivity increased from almost 0 for a reduced catalyst to 75% for a sulfurized catalyst. The effect on the selectivity of the addition of alkali metals increased in the order sodium > potassium > lithium. Temperature-programmed reaction (TPR) experiments, conducted by flowing deuterium onto the sulfurized catalysts, were used to characterize the sulfur species that easily desorbed with hydrogen. The results indicated that HS- is the major species on the catalysts and that the adsorbed HS- bridges the PtSir and the Na2Sir particles. Re-reduction of the sulfurized Pt-Na2O/Al2O3 catalyst to remove the HS- decreased the selectivity from 75 to 8%, implying that HS- is effective in enhancing the selectivity.
  • Ryoji Takahashi, Satoshi Sato, Toshiaki Sodesawa, Masanori Suzuki, Kat ...
    2000 Volume 73 Issue 3 Pages 765-774
    Published: 2000
    Released: October 31, 2001
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    A microporous silica gel was prepared by a sol-gel process in the presence of ethylene glycol (EG) and its oligomers (oligoEG), and the pore formation process was investigated by using NMR and TG-DTA. The micropore volume changed with the polymerization degree of oligoEG, and showed a minimum at the trimer of EG. An attractive interaction between silanol and organic additives plays a key role in micropore formation: the interaction inhibits the bond formation of Si-O-Si during drying and heating, and heterogeneous domains which convert into micropore are formed after the combustion of additives. There are two kinds of interaction: one is ester (Si-OR) bond formation of a silanol with an end hydroxy group of additives; the other is hydrogen bonding between a silanol and an ether oxygen of additives. The former interaction is significant for EG. With increasing length of oligoEG, however, the former interaction rapidly disappears, while the latter becomes stronger. Because of a minimum in the combination of these interactions, the minimal volume of the micropore is observed.
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