Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 69 , Issue 2
Showing 1-35 articles out of 35 articles from the selected issue
  • Ryoichi Nakagaki, Kiyoshi Mutai
    1996 Volume 69 Issue 2 Pages 261-274
    Published: 1996
    Released: June 20, 2006
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    Orientation rules for photochemical nucleophilic substitutions are deduced from intramolecular photoreactions of some bichromophoric chain molecules, p-O2NC6H4O(CH2)nNHC6H5. The lower homologues undergo photochemical nucleophilic substitutions which can be classified as a Smiles-type photorearrangement. The photochemistry of this type of bifunctional chain species depends upon the methylene chain length. When the chain length is sufficiently long, the photorearrangement is totally forbidden. Photoredox reactions are the only accessible reaction processes for the higher homologues. The photoredox reaction consisting of cage and escape pathways is modulated by an external magnetic field. The magnetic field effects on the end product distribution are due to changes in the intersystem crossing rate induced by hyperfine interaction within biradical intermediates.
  • Kohei Uosaki, Shen Ye, Namiki Sekine
    1996 Volume 69 Issue 2 Pages 275-288
    Published: 1996
    Released: June 20, 2006
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    An electrochemical tunneling spectroscopy (ETS) system is constructed to study the electronic structure of semiconductor/electrolyte interfaces. By using this system, the tunneling current of GaAs (100) single crystal electrodes in solution was measured as a function of electrode potential at a constant sample-tip distance. Tunneling current flowed in the forward bias region; the current depended on the bias, i.e., the potential with respect to the flat band potential. It decreased by decreasing the bias and became zero near the flat band potential. This behavior can be explained by considering the potential dependence of the surface concentration of the majority carriers. The space charge layer within the semiconductor formed in the reverse bias region worked as an extra barrier for the tunneling process; therefore, no tunneling current was observed in this potential region. Current in the direction opposite to that in the forward bias region flowed as the reverse bias became very large, although this current was very small. In this potential region, the thickness of the space charge layer near the Fermi level of the tip became thinner and electrons were able to tunnel through the barrier. Effects of the doping density, the tip potential, the pre-set tunneling current and the initial sample potential as well as the surface treatment on the tunneling current–electrode potential relation were investigated in detail at n-GaAs(100) single crystal electrodes. The tunneling behaviors in the forward and reverse bias regions were discussed semi-quantitatively based on the calculation of surface electron concentration and the transmission coefficient through the space charge barrier, respectively.
  • Michinori Suginome, Hideaki Oike, Sang-Soo Park, Yoshihiko Ito
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 289-299
    Published: 1996
    Released: June 20, 2006
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    Four- to seven-membered cyclic bis(organosilyl)palladium(II) complexes were synthesized by oxidative addition of cyclic disilanes onto bis(t-butyl isocyanide)palladium(0) as well as by intramolecular metathesis of the two Si–Si bonds of bis(disilane)s with the palladium(0) complex. The 4-membered bis(organosilyl)bis(t-butyl isocyanide)palladium complex prepared from 2,2-bis(1,1,2,2-tetramethyl-2-phenyldisilanyl)-1,3-dithiane was characterized by a single-crystal X-ray method, which showed an unusually short cross-ring Si–Si distance in the 4-membered ring. The reactivities of the cyclic bis(organosilyl)bis(t-butyl isocyanide)palladium complexes toward phosphines, cyclic disilanes, and alkynes were also examined. Cyclic organosilicon compounds were synthesized by bis-silylation of alkynes with cyclic bis(organosilyl)palladium intermediates generated by the intramolecular metathesis. The bis-silylation was also applicable for electron-deficient alkenes: α,β-unsaturated ketones gave 7-membered 1,4-bis-silylation adducts, whereas the corresponding ester and nitrile gave 5-membered 1,2-adducts in high yields.
  • B. B. Panda, G. Dixit, B. Behera
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 301-303
    Published: 1996
    Released: June 20, 2006
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    The apparent molar volume and the viscosities of N-ethylpyridinium iodide in water at 25, 30, 35, and 40 °C are reported. The apparent molar volumes decrease with increasing temperature and obey Masson’s equation. The high values of φv° and Sv* indicate strong ion–ion interactions in water. φv° is linearly related to temperature. The viscosity data were analyzed by the Jones–Dole equation. The B values indicate greater solvation. The thermodynamic parameters of viscous flow and hydration number are discussed in terms of hydrophobic hydration and solvent-shared ion-pairs.
  • Terutake Koizumi, Kenji Morihashi, Osamu Kikuchi
    1996 Volume 69 Issue 2 Pages 305-309
    Published: 1996
    Released: June 20, 2006
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    The NMR 15N–6Li coupling constants 1JNLi in LiNH2 and LiN(CH3)2 monomers and their oligomers and mixed aggregates with LiCl were calculated using ab initio self-consistent perturbation theory and the relation between the molecular structure and 1JNLi values was examined. The calculated 1JNLi values in the monomers are influenced by solvation and agree well with experimetal values when model solvent molecules are coordinated at the lithium atom. The calculated 1JNLi values in cyclic oligomers also agree well with experiment and support the structures derived from NMR experiments in solution. For the mixed trimer, (LiNH2)2LiCl, a ladder form was obtained as the most stable structure when the lithium atoms are solvated by two H2O or two NH3 molecules.
  • Mojtaba Shamsipur, Naader Alizadeh, Hossein Gharibi
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 311-314
    Published: 1996
    Released: June 20, 2006
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    A membrane electrode selective for hexadecylpyridinum bromide was used to study the micellization of the surfactant at various temperatures (25—50 °C). The thermodynamic parameters ΔH°m and ΔS°m were calculated from the temperature dependence of the equilibrium constants for micellization of the surfactant. It was clearly shown that the entropy of micellization obtained by the usual approximate method from ΔG°m = (2 − α)RTln Xcmc is much more positive than the corresponding exact value calculated from direct activity measurements.
  • Yoshifumi Koide, Hirotaka Sato, Hideto Shosenji, Kimiho Yamada
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 315-319
    Published: 1996
    Released: June 20, 2006
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    Resorcinol-type calix[4]arenes bearing four alkyl side chains ([4]Ar-Rn) have been applied as a liquid surfactant-membrane in the concentration process of Cs+. [4]Ar-Rn formed a highly stable water-in-oil (w/o) emulsion for a mixture of toluene and HCl solution, and the w/o emulsion became a w/o/w emulsion by stirring it in a Cs+ solution. The Cs+ in the outer aqueous solution was transported through the liquid surfactant-membrane of w/o/w emulsion into the inner HCl solution. [4]Ar-R6 was the most effective emulsifier capable carrying Cs+ in the [4]Ar-Rn bearing alkyl chains of various lengths. The final amount of the transported Cs+ was 9 times as much as the molar of [4]Ar-R6 in 100 min at the initially 10 times molar Cs+ in the outer solution (turnover number: 9). Moreover, the Cs+ was transported selectively from a mixture of alkali metal ions (Cs+, Na+, and K+) by using 2 × 10−4 mol of [4]Ar-R6.
  • Keisaku Kimura
    1996 Volume 69 Issue 2 Pages 321-324
    Published: 1996
    Released: June 20, 2006
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    A formula for the photoincreased van der Waals attractive force is derived, which includes the effects of the frequency of illuminated electromagnetic waves and of the size of particles. The interparticle interaction energy as a function of the frequency of the electromagnetic wave shows a sharp maximum at the resonance frequency. In the small limit of the size, the van der Waals force under on-resonance irradiation conditions approaches that of molecules and in the large limit the force is drastically reduced. The largest interparticle interaction is found at the size of a few tens of nm. This novel effect is found to be typical of nano-systems.
  • Hayao Imamura, Koji Igawa, Yoshihisa Sakata, Susumu Tsuchiya
    1996 Volume 69 Issue 2 Pages 325-331
    Published: 1996
    Released: June 20, 2006
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    Upon introducing of lanthanide metals (Ln : Eu or Yb) onto a Pd surface by the reaction of Pd/SiO2 with Eu or Yb metal dissolved in liquid ammonia, the ability of considerable hydrogen uptake by the catalyst appeared during the hydrogenation reaction. Hydrogenation over supported lanthanide–palladium bimetallic catalysts was studied at 173—213 K, especially concerning the effects of the reactants, support materials, Pd particle sizes, and dispersion on the hydrogenation behavior with the hydrogen uptake. For the hydrogenation of ethene, propene, butene or butadiene, considerable hydrogen uptake occurred preferentially, followed by hydrogenation using the hydrogen taken up the catalyst. The hydrogenation occurred by a rate-limited hydrogen uptake process. In marked contrast to olefin and butadiene, no hydrogen uptake was observed for the hydrogenation of acetylene, indicating the progress of the reaction by a different mechanism. The support materials (SiO2, Al2O3, ZrO2, MgO, and TiO2), Pd particle sizes and Pd dispersion in Pd/support were important factors in determining the hydrogen uptake by supported Ln–Pd catalysts and the resulting hydrogenation behavior.
  • Atsuko Nakayama, Kazuya Suzuki, Toshiaki Enoki, Kei-ichi Koga, Morinob ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 333-339
    Published: 1996
    Released: June 20, 2006
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    Activated carbon fibers (ACF) consist of microporous carbon with a huge specific surface area (SSA) ranging from 700 m2 g−1 to 3000 m2 g−1, and a having random structures consisting of an assembly of micrographites with a dimension of ca. 20 × 20 Å2. The electrical conductivity and magnetic susceptibility were investigated for ACFs with SSA = 1000 and 2000 m2 g−1 in order to clarify the relation between the electronic properties and the structure of ACF having a random network of micrographites. The electrical conductivity is explained by the two-dimensional variable-range hopping conduction at lower temperatures and thermally activated conduction at higher temperatures. The introduction of N2 or O2 gas to a sample induces a change in the conductivity, which is considered to be caused by a structural change and a charge transfer between dangling bonds and O2 gas. The observed value of the orbital diamagnetic susceptibility is considerably small compared with that of a condensed polycyclic aromatic hydrocarbon having the same dimensions as that of the micrographite in ACF. This implies that the micrographitic domains have a deformed planar structure with the presence of defects.
  • Yoshito Chida, Hitoshi Watarai
    1996 Volume 69 Issue 2 Pages 341-347
    Published: 1996
    Released: June 20, 2006
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    Protonation of tetraphenylporphyrin (TPP) and octaethylporphyrin (OEP) in toluene/acid systems was investigated by a high-speed stirring method. In toluene/sulfuric acid system, the adsorption of the diprotonated TPP and the monoprotonated OEP at the liquid–liquid interface was found, while in other acid systems including hydrochloric acid, perchloric acid, and trichloroacetic acid, the ion-association extraction of H2TPP2+ and HOEP+ was observed as well, depending on the nature of the counter anions and the concentration of the acids. An inverted correlation was suggested between the adsorption constants of the protonated porphyrins and the extraction constants of the acids with the porphyrins.
  • Kenji Toda, Yutaka Kameo, Satoru Kurita, Mineo Sato
    1996 Volume 69 Issue 2 Pages 349-352
    Published: 1996
    Released: June 20, 2006
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    Intercalation of water was observed in a layered perovskite compound, NaEuTiO4, leading to its hydrated derivatives. There are some metastable intermediates in the hydrated derivatives. The hydration process includes several steps that are topotactic. The crystal structure of the hydrated derivatives was identified by Rietveld analysis for the powder X-ray diffraction pattern. It is confirmed that the water molecules are inserted into the sodium layer of NaEuTiO4.
  • Kuniaki Murase, Gin-ya Adachi, Masashi Hashimoto, Hiroshi Kudo
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 353-357
    Published: 1996
    Released: June 20, 2006
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    Vaporization of the LnCl3–KCl (Ln = Nd and/or Er) equimolar molten mixture was investigated at 1018—1273 K by means of Knudsen effusion mass spectrometry. The vapor species KCl, K2Cl2, NdCl3, and KLnCl4 were found in the vapor over the melt, and their vapor pressures were evaluated for the NdCl3–KCl system. Volatility enhancement of NdCl3 by the formation of the vapor complex KNdCl4 decreases with increase in temperature. A relatively small enthalpy change, −10 ± 21 kJ mol−1, of the isomolecular exchange KNdCl4(g) + KCl(g) = NdCl3(g) + K2Cl2(g) suggests that the structural change of the reaction is not drastic and that the KNdCl4(g) complex has two bridging and two terminal chlorine atoms.
  • Isao Kawafune, Gen-etsu Matsubayashi
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 359-365
    Published: 1996
    Released: June 20, 2006
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    β-Isomers of A-type vanadium-trisubstituted nonatungstophosphate anion salts were synthesized by a condensation of NaVO3 and A-Na9[PW9O34]·7H2O in an aqueous hydrochloric acid and 1,4-dioxane mixed solution. Their geometries were characterized by IR, 31P, 51V, and 183W NMR spectroscopies. The tetrabutylammonium salt of the β-isomer, A-β-(NBun4)4H2[PV3W9O40], isomerizes to the corresponding α-isomer both in the solid state and in solution under mild conditions, which can be directly followed by FT-IR and 31P NMR spectroscopies. The kinetics of the isomerization in the solid state had a first-order rate constant at 40 °C, k1 = 2.19 × 10−7 (s−1), together with ΔH = 93.3 (kJ mol−1) and ΔS = −77.3 (J K−1 mol−1). On the other hand, A-β-Cs6[PV3W9O40] and A-β-(NBun4)6[PV3W9O40], which have no protons in the cation part, do not isomerize under the same conditions. The β-to-α isomerization is promoted by protonation at the bridging oxygen atom in the W–O–W bond of the polyanion.
  • Kazuhiko Fukushima, Atsushi Kanayama, Yoshihiro Matsumoto, Shin Ono, T ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 367-377
    Published: 1996
    Released: June 20, 2006
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    The thermal decomposition and mass spectra of the N-phenyl- (1), N,N′-diphenyl- (2), and N,N′,N′-triphenylphosphoric triamides (3) were investigated. DTA-TG/DTG, TG-TRAP-GC/MS measurements, IR spectroscopic analyses, mass spectrometric analyses, HPLC analyses, and a kinetic study were carried out to investigate the thermal decomposition. From the analytical results, it was suggested that 1 decomposed while liberating ammonia and aniline, and condensed in several stages; its thermal products at about 160 °C contained 2. Compound 2 decomposed and condensed to form some condensed products at about 200 °C; its thermal products also contained 3. Compound 3 decomposed while liberating aniline to form a cyclic dimer, while the existence of other thermal products was also observed; the cyclic dimer further pyrolyzed in several stages, and 1 and 2 formed a similar condensed product in the 400 to 500 °C temperature range, though that for 3 was different. In addition, the apparent activation energy of the thermal decomposition was estimated and the thermal decomposition process was investigated based on this variation. In the mass spectra using electron impact, 1, 2, and 3 were cleaved along with an elimination of ammonia and/or aniline to form a three-coordinate phosphenimidic amide.
  • Tadanobu Sato, Atsushi Suzuki, Ken Sakai, Taro Tsubomura
    1996 Volume 69 Issue 2 Pages 379-388
    Published: 1996
    Released: June 20, 2006
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    A synthesis in good yield of a new hexaimino cryptand containing two tris(2-aminoethyl)amine moieties bridged by three naphthylene groups is reported. Ag+ and Cu+ cryptates of the ligand have also been prepared and characterized. The cryptand and cryptates have been structurally analyzed by X-ray diffraction, unveiling three different conformations. The macrobicyclic ligand has an anti conformation in the cryptand, but has a sym form in each cryptate. Although the Ag+ cryptates have a symmetric structure on the three arms, one of the three arms in the Cu+ complex shows remarkable bending. The bent conformation is intrinsic of the Cu+ complex, as indicated by X-ray analyses and MM2 calculations. The temperature dependence of the 1H NMR spectra has also been investigated, revealing fluxional behaviors of the ligand in each compound.
  • Takayuki Kayatani, Yoshihito Hayashi, Masatatsu Suzuki, Katsuhiko Inom ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 389-397
    Published: 1996
    Released: June 20, 2006
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    A dicopper(II) complex with a novel unsymmetric dinucleating ligand, H2L-1, which can provide donor atom, coordination number, and geometric asymmetries at metal centers, [Cu2(L-1)(CH3COO)]ClO4·H2O·0.5NaClO4 (1), was synthesized, where H2L-1 is a racemic 1-bis(2-pyridylmethyl)amino-3-salicylideneaminopropan-2-ol. The ligand is a hybrid one of 1,3-bis[bis(2-pyridylmethyl)amino]propan-2-ol (Htpdp) and 1,3-bis(salicylideneamino)propan-2-ol (H3L-2). Crystal structure of 1 was determined by X-ray crystallography. Complex 1 crystallizes in monoclinic space group C2/c with a = 42.704(8), b = 12.689(6), c = 29.008(9) Å, β = 128.28(1)°, and Z = 16. The crystal structure showed that two stereoisomers (1a and 1b) are present in solid state. This is attributable to the presence of an enantiomeric pair of L-1. Dinuclear cations consist of one square-planar site with a NO3 donor set and one five-coordinate site with a N3O2 donor set, which are linked by an endogenous alkoxide bridge of L-1 and an exogenous acetate bridge. A powdered sample of 1 shows weak antiferromagnetic interaction (2.60 B.M./Cu2 at 300 and 1.81 B.M./Cu2 at 5 K). Cryomagnetic data is analyzed using two exchange coupling constants, J1 = −0.18 cm−1 and J2 = −9.05 cm−1. EHMO calculations revealed that the observed weak antiferromagnetic interaction(s) compared with that found for [Cu2(L-2)(CH3COO)] (3) (J = −85 cm−1) is reasonably interpreted in terms of the energy gap and the nature of HOMO and LUMO. Some other physicochemical properties of the complex are discussed in comparison with those of the parent complexes, [Cu2(tpdp)(CH3COO)]2+ (2) and [Cu2(L-2)(CH3COO)] (3).
  • Masahiro Mikuriya, Keiichi Nakadera, Takanori Kotera
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 399-405
    Published: 1996
    Released: June 20, 2006
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    Dinuclear and tetranuclear nickel(II) complexes with 2,6-bis(salicylideneaminomethyl)-4-methylphenol (H3L), [Ni2(L)(pz)(Hpz)(CH3OH)]·CH3OH (1) and [Ni4(L)2(pz)2(CH3OH)] (2) (Hpz = pyrazole), have been synthesized and characterized by infrared and electronic spectra, and by temperature dependence of magnetic susceptibilities (80—300 K). The molecular structures of 1 and 2 were determined by single-crystal X-ray structure analysis. Complex 1 is a mixed-spin state complex in which one metal center is square planar and the other octahedral. Complex 2 has a zigzag tetranuclear structure, in which two dinuclear units with mixed spin-states are associated by two phenoxo-bridges and one methanol bridge.
  • Jitender M. Khurana, Abhijit Ray
    1996 Volume 69 Issue 2 Pages 407-410
    Published: 1996
    Released: June 20, 2006
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    A chemoselective reductive coupling of nitroarenes using magnesium in methanol has been reported at ambient temperature. While the cyano, formyl, methoxycarbonyl, methyl, methoxy, phenyl, amino, and chloro groups are unaffected, iodo and bromo groups undergo dehalogenation but in a slower reaction than the coupling of nitro group. The coupling is believed to be proceeding via SET from Mg to nitroarenes.
  • Tetsuro Tsuda, Tetsuya Furuike, Shin-Ichiro Nishimura
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 411-416
    Published: 1996
    Released: June 20, 2006
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    Versatile intermediates for the syntheses of cell-surface oligosaccharides bearing N-acetyllactosamine units have been prepared from a readily available 1,6-anhydro-β-lactose as a key starting material. Regioselective chemical manipulations of 1,6-anhydro-β-lactose were carried out in a stepwise procedure and gave fully-protected lactosamine derivatives. It was clearly suggested that modification at C-3′ position of the galactose residue and the following introduction of a sterically hindered leaving group at C-2 position of the reducing glucose remarkably accelerated and facilitated further derivatization of this potential disaccharide material. Selective generation of hydroxyl groups at C-3, C-3′, and/or C-6′ positions proceeded smoothly in mild conditions and afforded a series of fully-functionalized disaccharide-acceptors in high yields.
  • Takashi Ito, Lin-Ming Wan, Makoto Minato
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 417-423
    Published: 1996
    Released: June 20, 2006
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    Molybdenocene derivatives with some chiral carboxylato ligand of the types, Cp2MoH(OCOR*), Cp2Mo(OCOR*)2, Cp2MoH(OCO-E*-OCO)MoHCp2, [Cp2Mo(OCOR*)]+R*CO2, are prepared by the reaction of Cp2MoH2 with chiral 2-methylbutanoic acid, mandelic acid, O-acetylmandelic acid, tartaric acid, and O,O′-diacetyltartaric acid in the presence of ketone and are characterized spectroscopically. Enantioselectivity in the reduction of the prochiral ketones using some of these hydridocarboxylato derivatives is examined.
  • Tadashi Mizutani, Yasushi Miki, Ruka Nakashima, Haruo Fujita, Hisanobu ...
    1996 Volume 69 Issue 2 Pages 425-429
    Published: 1996
    Released: June 20, 2006
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    As a model for prebiotic sugar formation under neutral to acidic conditions, reactions of formaldehyde over hydrotalcite-type catalysts were investigated. Heating an aqueous solution of formaldehyde at 140—200 °C for 12 h over Ni–Fe hydrotalcite-type catalyst afforded 2-hydroxy-3,3-bis(hydroxymethyl)-γ-butyrolactone selectively, a 5.8% yield based on gas–liquid chromatographic analysis. The structure was identified by 1H and 13C NMR and 1H–13C HSQC, HMBC and 13C–13C 2D INADEQUATE NMR experiments.
  • Yasumasa Fukushima
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 431-439
    Published: 1996
    Released: June 20, 2006
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    The alternating amphiphilic copolypeptide poly(Asp–Leu–His–Leu–Ser–Leu) was prepared by the synthesis and polymerization of the respective hexapeptide in order to obtain a stable β-sheet polypeptide with hydrolytic catalytic activity, like that of a serine protease. The conformation and conformational transitions in aqueous solution and in water–organic solvent mixtures were determined by circular dichroism measurements. The polypeptide reveals a very strong tendency to adopt a β-sheet structure, which is accomplished at below pH 10.0, and even by adding sodium chloride or various alcohols. However, a partial α-helical conformation is observed in an aqueous solution at pH 12.0; also, an α-helix to β-sheet conformational transition occurs upon adding 1 M NaCl. The polypeptide is a more effective catalyst than the peptide hexamer, the amino acids mixture, or imidazole for the hydrolysis of p-nitrophenyl derivatives, and catalyzed the hydrolytic reaction of the substrates more effectively with increasing their hydrophobicity. It is likely that the enhanced hydrolytic catalyst of the polypeptide may be responsible for increasing the nucleophilicity by the electrostatic interactions or condensation effect of the substrates by hydrophobic interactions. The polypeptide would make good models for constructing novel proteins with catalytic properties involving β-sheet structures.
  • Kazuhiro Kobayashi, Kouichi Yokota, Hideki Akamatsu, Osamu Morikawa, H ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 441-443
    Published: 1996
    Released: June 20, 2006
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    The reactions of sulfoxides bearing α-hydrogen(s) (RSOCHR1R2: R-alkyl or aryl; R1, R2 = H, alkyl, or aryl) with Grignard reagents (R3MgBr: R3 = Et, Ph, or vinyl) in the presence of the diisopropylaminomagnesium reagent, generated in situ by the treatment of diisopropylamine with the appropriate Grignard reagents in diethyl ether, have resulted in the formation of the corresponding sulfides (RSCR1R2R3) in moderate to good isolated yields.
  • Masaaki Mishima, Toshifumi Ariga, Takatsugu Matsumoto, Shinjiro Kobaya ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 445-451
    Published: 1996
    Released: June 20, 2006
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    Gas-phase basicities (GB) of a series of substituted phenylacetylenes were determined by measuring the standard free energy changes of proton transfer equilibria using a pulsed ion cyclotron resonance mass spectrometer. The LArSR analysis of the substituent effect on the GB values gave an r+ value of 1.18 and a ρ value of −14.0. The r+ value is significantly larger than that obtained for the GB of α-methylstyrenes but is smaller than that for chloride ion affinities of benzyl cations, while the ρ value is similar in the three systems. This means that the 1-phenylvinyl cation has an intermediate resonance demand between those of the α-cumyl cation and the benzyl cation. Further, the r+ value of 1.18 for 1-phenylvinyl cation obeys the same “resonance demand vs. carbocation stability" relationship observed for a series of ordinary sp2-hybridized benzylic carbocations. This reveals that the π-delocalization mechanism in the vinyl cation system has no unique feature but it is a part of a continuous spectrum of resonance demands of varying benzylic carbocations characterized by r+ = 1.18. A comparison of the present GB values with the substituent effect for the acid-catalyzed hydration of phenylacetylenes in solution has shown that the r+ value is perceptibly smaller in the latter case. This suggests that the π-delocalization in the transition state differs considerably from that of the stable phenylvinyl cation intermediate. This is in contrast to the situation in the SN1 solvolysis where the r+ value is identical to the value characteristic for the formation of the fully developed carbocation.
  • Kyosuke Satake, Kazuyuki Hikasa, Hajime Itoh, Hideki Okamoto, Masaru K ...
    1996 Volume 69 Issue 2 Pages 453-457
    Published: 1996
    Released: June 20, 2006
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    A reaction of electrophilic bromination of norbornadiene homologs such as bicyclo[2.2.2]octa-2,5-diene (4) and bicyclo[3.2.2]nona-6,8-diene (7) with bromine gave hitherto unknown skeleton rearranged dibromides. The rearrangement may proceed via a bromonium cation of starting diene to give bicyclo[3.2.1]octene or bicyclo[3.3.1]nonene skeleton in respective cases. The observed rearrangement reactions are also confirmed in 6,7-bis(methoxycarbonyl) derivatives of bicyclodiene 7 under similar conditions.
  • Kiyoharu Hayano, Haruhisa Shirahama
    1996 Volume 69 Issue 2 Pages 459-464
    Published: 1996
    Released: June 20, 2006
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    The treatment of (6E, 9E)-2,3-epoxy-3,7,11,11-tetramethylcycloundeca-6,9-diene with Et2O·BF3 produced four novel transannular cyclized compounds of (4E)-(1S*, 8S*, 9S*)-8-acetoxy-6,6,9-trimethyl-2-methylenebicyclo[7.2.0]undec-4-ene (13), (2Z, 4E)-(1S*, 8S*, 9S*)-8-acetoxy-2,6,6,9-tetramethylbicyclo[7.2.0]undeca-2,4-diene (14), (6E)-(1R*, 2R*, 3S*, 10R*)-3-acetoxy-2,5,5-trimethyl-9-methylenebicyclo[8.1.0]undec-6-ene (15), and (4E)-(1S*, 2S*, 8S*, 9S*)-2,8-diacetoxy-2,6,6,9-tetramethylbicyclo[7.2.0]undec-4-ene (16) together with three new acetates: (2E, 5E, 8E)-1-acetoxy-2,6,10,10-tetramethylcycloundeca-2,5,8-triene, (1E, 6E)-3,9-diacetoxy-2,5,5,9-tetramethylcycloundeca-1,6-diene, and (4E, 7E)-1-acetoxy-3,3,7-trimethyl-11-methylenecycloundeca-4,7-diene. The configurations of the bicyclo[7.2.0]undecane skeletons (13, 14, and 16) and 15 maintained the shape of TC and CT conformers of the original epoxide, respectively.
  • Tateaki Wakamiya, Takatoshi Nishida, Ryusaku Togashi, Kunio Saruta, Ju ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 465-468
    Published: 1996
    Released: June 20, 2006
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    Nα-Fmoc-O-[(benzyloxy)hydroxyphosphinyl]serine and Nα-Fmoc-O-[(benzyloxy)hydroxyphosphinyl]threonine were prepared in order to be utilized for the synthesis of phosphoserine- or phosphothreonine-containing peptides based on the Fmoc-mode pre-phosphorylation strategy. These derivatives were obtained as crystalline compounds, which are favorable for use as building blocks for an automated peptide synthesis by a solid-phase method.
  • Yajnavalkya Subray Bhat, Jagannath Das, Anand Bhimrao Halgeri
    1996 Volume 69 Issue 2 Pages 469-472
    Published: 1996
    Released: June 20, 2006
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    The chemical vapor deposition of silica on Ga-MFI zeolite was carried out using tetraethyl orthosilicate. The enhancement in para selectivity during toluene alkylation with the extent of silica deposition was closely monitored. The effect of reaction temperature on the behavior of silica deposited Ga-MFI zeolite was established. A deactivation trend in toluene conversion was observed when the zeolite was employed for alkylation for longer periods. The reasons for catalytic deactivation and stability enhancement by in situ coking are discussed.
  • Takayuki Ohta, Shiho Sano
    1996 Volume 69 Issue 2 Pages 473-476
    Published: 1996
    Released: June 20, 2006
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    An amphiphilic graft-copolymer consisting of ionic segments (quaternary ammonium groups) and aliphatic polyester segments which are compatible with various polymers was synthesized by radical copolymerization of a (methacryloxyethyl)trimethylammonium chloride and a poly(β-methyl-δ-valerolactone) macromer. Polymer blends containing this graft-copolymer showed both low surface resistance and low volume resistivity, due to the network formation of the graft-copolymer in the polymer matrix. Scanning electron microscopy revealed that the graft copolymer forms interconnected granular aggregates, which function as ion-conducting channels.
  • Seiichi Kanda, Fumio Yamamoto
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 477-483
    Published: 1996
    Released: June 20, 2006
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    An example of proton conduction in a coordination polymer was examined. Dependence of the specific conductivity on hydrogen pressure was quite strong in the title compound with a few types of protodes. The mechanism of electric conduction of this coordination polymer is discussed in connection with related phenomena of the same compound.
  • Wataru Ueda, Toshio Isozaki, Fuyuhiko Sakyu, Satoshi Nishiyama, Yutaka ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 485-491
    Published: 1996
    Released: June 20, 2006
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    Bismuth chloride oxides having four distinct structural types and lanthanum-substituted bismuth chloride oxides were tested as catalysts for the oxidative coupling reaction of methane. Their catalytic properties were compared in relation with their structure. BiClO, which has a layer structure with a double chlorine sheet, so-called X2 type structure, was most active for the methane conversion but less selective for the formation of C2 hydrocarbons. The catalyst structure was quite unstable, so that the activity decreased markedly until reaching a constant level, while the selectivity increased. During these changes of the catalytic performance BiClO changed by liberating chlorine to Bi24Cl10O31, the so-called Arppe’s phase, and then finally to a highly stable and selective Bi3ClO4 phase which was constructed with a double metal oxygen sheet and a single chlorine sheet. When more chlorine was removed from Bi3ClO4, Bi12Cl2O17, which has quintuple oxide sheets and a single chlorine sheet, was formed as an intermediate phase to be less selective for C2 hydrocarbons and ultimately Bi2O3 was formed with no chlorine, to be nonselective. The substitution of Bi in Bi3ClO4 for La caused a decrease of the C2 selectivity, whereas the Bi3−xLaxClO4 catalysts treated with NaCl brought about a maximum yield of C2 hydrocarbons.
  • Kazunori Tanaka, Shohei Isomura, Hayato Kaetsu, Yoshifumi Yatsurugi, M ...
    1996 Volume 69 Issue 2 Pages 493-498
    Published: 1996
    Released: June 20, 2006
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    Powder silica and elemental silicon enriched with 30Si were prepared at the request of nuclear physicists who had needed the isotopic samples for their research on neutron-rich nuclei. The enrichment of 30Si was performed by means of the IRMPD of Si2F6 to SiF4 using a CO2 laser. The 30Si-enriched SiF4 was further converted either to silica by hydrolysis with aqueous ammonia or to silicon by LiAlH4 reduction to SiH4 followed by its thermal decomposition. As the final products we obtained 11.35 g of silica with 20.6% 30Si, and 3.06 g of silicon with 17.5% 30Si.
  • Hiroyuki Nishide, Takashi Kaneko, Shuichi Toriu, Yoshihiro Kuzumaki, E ...
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 499-508
    Published: 1996
    Released: June 20, 2006
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    Poly[[2- or 4-[N-t-butyl-N-(triethylsiloxy- or t-butyldimethylsiloxy)amino]-1,4- or 1,2-phenylene]vinylene] was synthesized by polymerizing 4- or 2-bromo-2- or 4-[N-t-butyl-N-(triethylsiloxy- or t-butyldimethylsiloxy)amino]styrene with a palladium catalyst, respectively. They were deprotected and chemically oxidized to yield poly(1,4- or 1,2-phenylenevinylene)s bearing a 2- or 4-substituted built-in nitroxide radical. The polyradicals were chemically stable, and their spin concentration was increased to 0.8 spin/unit. A SQUID measurement which included the corresponding diradicals and triradicals indicated that a partial, but strong, intramolecular ferromagnetic coupling was established through the conjugated backbone, despite a spin defect in the side radical moiety, for the poly(1,2- phenylenevinylene) bearing 4-substituted built-in nitroxide radical.
  • Etsuhiro Muneyama, Atsuhiro Kunishige, Kyoji Ohdan, Mamoru Ai
    Type: Accounts
    Subject area: AI
    1996 Volume 69 Issue 2 Pages 509-513
    Published: 1996
    Released: June 20, 2006
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    In the absence of oxygen, P/Fe = 1.2 catalyst samples are reduced by hydrogen or isobutyric acid to form Fe2P2O7 via Fe3(P2O7)2, while the P/Fe = 1.0 samples are reduced directly to Fe2P2O7; without passing through Fe3(P2O7)2. Fe2P2O7 is oxidized by air to an unknown compound (Y-phase), but not to Fe3(P2O7)2 nor FePO4. The Y-phase is reduced to Fe2P2O7. During the use in the oxidative dehydrogenation of isobutyric acid, freshly calcined catalysts are reduced to Fe3(P2O7)2, while the Fe2P2O7 catalysts are oxidized to Y-phase, though the rates are very slow. The catalytic activity and selectivity are scarcely affected by variation in the structure of the iron phosphate catalyst and in the oxidation states of iron ions. The P/Fe and Fe2+/(Fe2++Fe3+) ratios on the surface, which were measured from cooled catalyst samples, are almost the same as those in the bulk.
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