Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 70 , Issue 5
Showing 1-35 articles out of 35 articles from the selected issue
  • Atsushi Kawachi, Kohei Tamao
    1997 Volume 70 Issue 5 Pages 945-955
    Published: 1997
    Released: June 13, 2006
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    Several types of α-alkoxy and α-amino substituted silyllithiums have been prepared as the first members of stable and/or well-characterizable functionalized silyllithiums. Described herein are new aspects of (1) three methodologies for preparation of functionalized silyllithiums, (2) high stability of (aminosilyl)lithiums, (3) low stability of (monoalkoxysilyl)lithiums, behaving as silylenoid species, (4) high stability of (dialkoxysilyl)lithiums, (5) high stability of (2-alkoxydisilanyl)lithium, (6) first examples of [2,3]-sila-Wittig rearrangement, and (7) synthetic utilization of (aminosilyl)lithiums.
  • Hitoshi Watarai, Masashi Gotoh, Narushi Gotoh
    1997 Volume 70 Issue 5 Pages 957-964
    Published: 1997
    Released: June 13, 2006
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    Extraction kinetic mechanism of Ni(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) was studied by a high-speed stirring spectrophotometry in heptane/water and toluene/water systems. The experimental results revealed that a rate-determining step was the 1 : 1 chelate formation of Ni2+ with 5-Br-PADAP adsorbed at the interface. In situ spectrophotometry of the heptane/water interface proved the formation of Ni(II) complex at the interface. The preferential adsorption of 5-Br-PADAP and its Ni(II) complex in heptane/water interface was correlated with the lower distribution constant in heptane/water than that in toluene/water. Molecular dynamics simulation could reproduce the preferential adsorptivity in heptane/water interface and then the higher reactivity with Ni2+ in the interface. The observed formation rate constants of the Ni(II) complex in bulk aqueous phase and the interfaces were smaller than those expected from the Eigen mechanism. Molecular mechanics calculation supported the ring-closure mechanism, previously postulated as the rate-determining step.
  • Hiroyuki Kusama, Yuko Yamashita, Katsuya Uchiyama, Koichi Narasaka
    1997 Volume 70 Issue 5 Pages 965-975
    Published: 1997
    Released: June 13, 2006
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    Phenethyl ketone oximes are converted to quinolines by the treatment with tetrabutylammonium perrhenate, trifluoromethanesulfonic acid, and chloranil in refluxing 1,2-dichloroethane. Azaspirotrienones can be synthesized from p-hydroxyphenethyl or 3-(p-hydroxyphenyl)propyl ketone oximes by applying the above method. Thus prepared azaspirotrienones are converted to quinolines by acid treatment.
  • Sebastião J. Formosinho, Luís G. Arnaut
    1997 Volume 70 Issue 5 Pages 977-986
    Published: 1997
    Released: June 13, 2006
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    The Intersecting-State Model (ISM) is used to calculated the absolute rate constants of self-exchange electron-transfer reactions (ET) of organic species. The systems studied include aromatic hydrocarbons, quinones, nitrobenzene, aromatic nitriles, tetracyanoethylene, aromatic amines, and alkylhydrazines. All of the calculated rates are within one order of magnitude of the experimental ones, and the correlation coefficient between the two sets is 0.96. An electron-tunneling model has been developed to calculate distance-dependent nonadiabatic factors of intramolecular ET. This model can be used with ISM to calculate intramolecular ET rates. The system biphenylyl-spacer-naphthyl in tetrahydrofuran, whose distance-dependent intramolecular rates were measured by Closs and Miller, was used to test our calculations, because its ET rates can be calculated without adjustable parameters. Our absolute rate calculations are in an order-of-magnitude agreement with the experimental ones.
  • Andrea Marchetti, Lorenzo Tassi, Alessandro Ulrici
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 987-991
    Published: 1997
    Released: June 13, 2006
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    The densities (ρ) and excess molar volumes (VE) for 1,2-dimethoxyethane + water binary mixtures were determined, when possible, at 19 different temperatures ranging from −10 up to +80 °C. The experimental measurements were used to test some empirical relations giving the dependence of the density on the temperature and binary composition: ρ = ρ(t), ρ = ρ(X1), and ρ = ρ(t,X1). Furthermore, the results of VE calculations are discussed in terms of the influence of interactions between the components, of the order and degree of packing in the mixtures, and of the free-volume differences.
  • Jeong-Gil Choi, Moon-Ki Jung, Saemin Choi, Tae-Keun Park, Il Hiun Kuk, ...
    1997 Volume 70 Issue 5 Pages 993-996
    Published: 1997
    Released: June 13, 2006
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    Vanadium nitride catalysts were synthesized by the temperature-programmed reduction of vanadium oxide (V2O5) with pure NH3. The resulting materials contained VN or VN with a negligible amount of vanadium sesquioxide (V2O3) in the bulk after the nitrization of V oxides, indicating that the structural properties of these materials were strong functions of the heating rate and space velocity employed. The V nitrides proved to be active NH3 decomposition catalysts. Since the activity varied with changes in the surface area and particle size, ammonia decomposition over the V nitrides appeared to be structure-sensitive. While detailed relationships between the catalytic activity and surface composition could not be ascertained, there was a direct correlation between the activity, and the surface area and grain-boundary length. The most active catalyst, VN-c, which contained the δ-phase, had the greatest grain-boundary length. The catalytic properties of V nitrides were comparable or superior to those of a Ni/SiO2·Al2O3 catalyst. These results suggested that the characteristics of the active sites in the vanadium nitrides were similar to those in the Group 8—10 metal-based catalysts.
  • Swarna M. Patra, Rama K. Mishra
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 997-1001
    Published: 1997
    Released: June 13, 2006
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    Octane isomeric molecules have been ordered by using the graph spectrum of the vertex adjacency matrix and a Fortran-77 program. The program not only orders the isomeric molecules into various subgroups, but also generates topological descriptors, which primarily depict the branching and linear characters of the molecule. These descriptors are correlated with different physical properties, like standard entropy (), standard entropy of formation (), heat of vaporization (Hv), octane number (MON), and A coefficient of Antoine equation. Good correlations of the descriptors with the above properties have been obtained.
  • Sadakatsu Nishikawa
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1003-1007
    Published: 1997
    Released: June 13, 2006
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    The ultrasonic absorption coefficients over frequency range from 1.0 to 220 MHz were measured in aqueous β-cyclodextrin solutions with 1-butanol and 2-methyl-2-propanol at 25 °C. A clear single relaxational absorption with a relaxation frequency from 5 to 20 MHz was observed in a solution with 1-butanol, while the relaxational absorption was found in a lower frequency range in a solution with 2-methyl-2-propanol. The cause of the relaxation was attributed to a perturbation of a chemical equilibrium associated with complexation between β-cyclodextrin (host) and alcohol (guest). The rate and equilibrium constants for the complexation were determined from the concentration dependence of the relaxation frequency for the solution with 1-butanol. The standard volume change of the reaction was also obtained from the maximum absorption per wavelength. These results were compared with those for complexation between β-cyclodextrin and 1-propanol, and were considered in relation to the alcohol molecular structure. It was found that the rate of complex formation is almost independent of the guest molecule, and, therefore, the equilibrium constant for the complexation is controlled by the rate of departure of the guest molecule from the host. From this fact, the rate parameters for a solution with 2-methyl-2-propanol were estimated, and the calculated ultrasonic relaxation parameter was compared with the experimental data.
  • Masaharu Komiyama, Kazumichi Ohashi, Yoshio Morioka, Jun’ichi Ko ...
    1997 Volume 70 Issue 5 Pages 1009-1013
    Published: 1997
    Released: June 13, 2006
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    Experimental examinations concerning the effect of the intrapellet activity profiles on a consecutive reaction were performed. The product selectivities in the liquid-phase hydrogenation of 1,3-butadiene over Pt/Al2O3 spheres were obtained for three types of intrapellet Pt distribution profiles: a uniform catalyst with an appreciable amount of Pt present throughout the support sphere, an eggshell catalyst with a Pt band deposited at the outer surface of the support sphere, and an inner-shell catalyst with a Pt band at the middle of its radius. In all of the three profiles a whole-pellet catalyst showed product distributions and activation energies very different from that of their respective powdered form. These results are interpreted and discussed in terms of the effect of diffusional limitations.
  • Ryotaro Kiyono, Atsuhito Komoto, Masayasu Tasaka, Takanori Yamaguchi, ...
    1997 Volume 70 Issue 5 Pages 1015-1020
    Published: 1997
    Released: June 13, 2006
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    Solvent transport across poly(styrene)-based anion-exchange membranes with various ion-exchange groups was measured under a temperature gradient to discuss the effect of hydrophobicity of the membranes on thermoosmosis. Two varieties of poly(styrene)-based copolymer membranes with 10 and 14% divinylbenzene as cross-linking agent were prepared as base membranes. Benzyltrimethylammonium, benzyltriethylammonium, benzyltripropylammonium, benzyltributylammonium, and benzyltripentylammonium were introduced in the base membranes as anion-exchange groups. The thermoosmotic volume flux toward the hot solution side decreased with increasing the length of alkyl groups (increasing hydrophobicity of the groups), and at last, for the membranes with benzyltripentylammonium, the direction of thermoosmosis reversed: from the hot to the cold solution side as is observed for usual hydrophobic membranes. The transported energy and the mean transported entropy of water in the membranes estimated from the data of thermoosmosis and that of osmosis measurements increased with increasing the hydrophobicity of the ion-exchange groups introduced in the membranes.
  • Takashi Kasamatsu, Takeo Kaneko, Takeshi Saito, Kensei Kobayashi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1021-1026
    Published: 1997
    Released: June 13, 2006
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    Abiotic formation of amino acid precursors in interstellar dusts (ISDs) by cosmic radiation was quantitatively examined. In order to study the formation of organic compounds in ISDs, ice mixtures of carbon monoxide (or methane), ammonia, and water made in a cryostat at 10 K were irradiated with high energy protons. Irradiated ice products were warmed up to room temperature, while sublimed gases were analyzed with a quadrupole mass spectrometer. Some hydrocarbons and alcohols were detected. Amino acid precursors, which gave amino acids after acid-hydrolysis, were detected in non-volatile products remaining on the substrate at room temperature. G-values of glycine precursors from methanol, ammonia, and water in solid state irradiation were about 6 × 10−4, which was about two orders less than those in gasous state irradiation. The present results suggest that a considerable amount of organic compounds formed in extraterrestrial environments were supplied to the primitive earth before the origin of life.
  • Hiroshi Sakai, Junzo Umemura
    1997 Volume 70 Issue 5 Pages 1027-1032
    Published: 1997
    Released: June 13, 2006
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    For interpretating the various phases appearing in a two-dimensional system, we have recorded in situ polarized FT-IR external reflection spectra of Langmuir films of stearic acid and cadmium stearate on the water surface at various surface areas, and evaluated the molecular orientation angles quantitatively. In the stearic acid monolayer, the orientation angle of the hydrocarbon chain from the surface normal decreased from 20° to almost 0° upon monolayer compression. In the cadmium stearate monolayer, on the other hand, the orientation angle (near 0°) did not change upon monolayer compression, though it was widely scattered at large surface areas, because of the formation of a rigid crystalline island. These results correspond well to the πA isotherms.
  • Kazuya Uejoh, Makoto Shimokozono, Motohiko Koyanagi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1033-1038
    Published: 1997
    Released: June 13, 2006
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    Phosphorescence spectra of m-fluorobenzaldehyde and its aldehyde deuterated derivative have been observed in the vapor phase at room temperature and in a methylcyclohexane matrix at 4.2 K. Paired band systems were detected for the vapor phase and for each of the two different crystallographic phases, α- and β-phases, and were attributed to two rotational isomers of the aldehyde group. Variable intensity changes between the two paired bands observed in the α-phase crystal are manifestations of the isomeric conversion in the ground state during crystallizations. An energy correlation of the rotational isomers between the lowest excited nπ* singlet and triplet states is given for the vapor phase and for the α-phase methylcyclohexane matrix.
  • Tomoki Tasaka, Ken Onda, Akiyoshi Hishikawa, Kaoru Yamanouchi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1039-1045
    Published: 1997
    Released: June 13, 2006
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    Photofragment excitation (PHOFEX) spectroscopy was applied to determine the dissociation energies of the B3Π1 states of HgAr and HgNe. The PHOFEX spectra were measured in the wavelength region where the laser-induced fluorescence spectrum of the B3Π1–X1Σ+ transition exhibits a continuum structure by probing the photolysis product of Hg(63P1) through the Hg(83S1–63P1) transition. By the spectral simulation of the threshold behavior of the high-resolution (Δν ≈ 0.08 cm−1) PHOFEX spectrum, the thresholds for the photodissociation reaction, HgRg → Hg(63P1) + Rg, were determined to be 39447.9(3) and 39536.0(5) cm−1 for Rg = Ne and Ar, respectively. From these thresholds, the dissociation energies, D0’s, of the B3Π1 states of HgNe and HgAr were determined to be D0(B3Π1; HgNe) = 9.8(3) and D0(B3π1; HgAr) = 61.8(5) cm−1, respectively. This direct determination of the dissociation energies of the B3Π1 states led to a determination of the D0’s for the X1Σ+ and A3Π0+ states; D0(X1Σ+; HgNe) = 35.6(3), D0(X1Σ+; HgAr) = 123.7(5), D0(A3Π0+; HgNe) = 68.7(3), and D0(A3Π0+; HgAr) = 348.8(6) cm−1. In addition, the (v′,0) vibronic bands of the B3Π1–X1Σ+ transition of HgAr were re-measured with high resolution for v′ = 0—8. From the transition wavenumbers of these vibronic bands, the Morse potential parameters were determined with high precision as ωe = 11.94(3) cm−1 and ωexe = 0.594(3) cm−1.
  • Yuko Hasegawa, Keiko Takashima, Fumie Watanabe
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1047-1052
    Published: 1997
    Released: June 13, 2006
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    The extraction constants (Kexn = [LnX3·nE]o/[Ln3+][X]3[E]on, n = 3 and/or 4) were determined across the lanthanoid series, when lanthanoids(III) were extracted from a 1 M sodium thiocyanate (NaX) solution into benzene and chlorobenzene containing trioctylphosphine oxide (TOPO, E). The dominant species were LnX3·4E for light lanthanoids and LnX3·3E for heavy ones. Although both extraction constants increased along with the atomic number, the difference in the magnitude of log Kex4 from log Kex3 to a less-polar solvent, benzene, was larger than that to chlorobenzene. The separation factor was similar either in light lanthanoids or in heavy lanthanoids to both solvents, reflecting the similar variation of the constants across the series. However, in the middle of the series, it was smaller upon using less-polar solvents than polar solvents. One of the reasons was the larger proportion of LnX3·4E, of which extraction constant did not change much in the middle of the series. In addition, when the concentration of TOPO was not in a large excess of the lanthanoid(III) concentration it was due to a greater consumption of TOPO; that is, the heavier lanthanoid(III), which was extracted better, required more TOPO molecules to be combined with LnX3, and into less-polar solvents lanthanoids(III) were extracted better than into polar solvents. Consequently the separation factor when using less-polar solvents was smaller than expected from the extraction constants.
  • Mayumi Danjo, Mitsutomo Tsuhako, Hirokazu Nakayama, Taro Eguchi, Nobuo ...
    1997 Volume 70 Issue 5 Pages 1053-1060
    Published: 1997
    Released: June 13, 2006
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    The intercalation of methylene blue (MB) into layered phosphates was examined in the presence of butylamine (BA) in order to clarify the mechanism of this reaction and the function of alkylamine, such as BA in the intercalation reaction. MB was not directly intercalated into layered phosphates, but could be intercalated in the presence of BA. The intercalation of MB was strongly influenced by the amount of BA used; that is, it was accelerated by the presence of BA, but inhibited by the presence of too much BA. Moreover, in the procedure which BA was previously intercalated into layered phosphates, it was found that the intercalation of MB can be achieved by removing BA from the interlayer region when BA is formed a monolayer in the phase, and depends on the orientation of BA in the interlayer region when BA forms a bilayer.
  • Teruhisa Komura, Tomohiro Kobayashi, Takahiro Yamaguti, Kousin Takahas ...
    1997 Volume 70 Issue 5 Pages 1061-1067
    Published: 1997
    Released: June 13, 2006
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    A poly[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium] perchlorate-coated glassy carbon electrode noticeably decreased the charge-transfer resistance (Rt) of quinhydrone relative to a naked glassy carbon electrode. The redox species was not concentrated into a polymer film; this result differs markedly from the very good absorption of anthraquinonesulfonates and indigosulfonates by a polymer film. The dependence of Rt and the interfacial capacitance on the film thickness implies that the charge-transfer process occurs at the film-solution interface, because the polymer film is appreciably electronically conductive at positive potentials. Because of a change in the film conductivities with the potential, the polymer-coated electrode increased the anodic peak current of quinhydrone by three times, but decreased its cathodic peak current by two fifths, relative to that of a naked electrode. Although the decrease in Rt at a polymer-film electrode is somewhat ascribed to an increasing area, which is due to a porous film surface, the electrocatalytic effect of the polymer film can be attributed to an increasing standard rate constant of the charge-transfer process; this increase may be due to the adsorption of quinhydrone on the polymer surface.
  • Tomonori Mori, Tadayoshi Yamamoto, Motowo Yamaguchi, Takamichi Yamagis ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1069-1075
    Published: 1997
    Released: June 13, 2006
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    (α-Amino acidato)ruthenium(II) complexes were dehydrogenated to give (α-imino acidato)ruthenium(II) complexes by chemical oxidation. (α-Imino acidato)ruthenium(II) complexes, [RuII{N(R1)=C(R2)CO2}(phen)2]+ (R1 = H, Me, or Bn, R2 = H; R1 = H or Me, R2 = Me; R1, R2 = –(CH2)3–) were obtained from the (α-amino acidato)ruthenium(II) complexes (glycinato, N-Me-glycinato, N-Bn-glycinato, (S)-alaninato, N-Me-(S)-alaninato, and (S)-prolinato complexes) by using diammonium cerium(IV) nitrate (CAN) as an oxidizing reagent. On the other hand, in the presence of hydrogen peroxide, the α-imino acidato complexes were converted to the corresponding α-imino acidato complexes, except for the glycinato and (S)-alaninato complexes. In particular, the iminoacetatoruthenium(II) complex, [Ru(NH=CHCO2)(phen)2]+, was synthesized for the first time by this method using CAN as an oxidizing reagent. Dehydrogenation with CAN is more facile and versatile than any other method that we have ever examined.
  • Takafumi Ueno, Masahiro Inohara, Norikazu Ueyama, Akira Nakamura
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1077-1083
    Published: 1997
    Released: June 13, 2006
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    A series of the model complexes containing ortho-substituted arenethiolato ligands, ((Et4N)2[Fe4S4(S-2-RCONHC6H4)4] {R = Ph (1), 4-MeO–C6H4 (2), and 4-F–C6H4 (3)} and (Et4N)2[Fe4S4{S-2,6-(RCONH)2C6H3}4] {R = Ph (4), 4-MeO–C6H4 (5), and 4-F–C6H4 (6)}) was synthesized and characterized by 1H NMR, IR spectroscopy, and cyclic voltammetry. The solution structures of these complexes are discussed based on their 1H NMR T1 data and molecular-dynamics calculations. Complex 4 has a shorter distance (av. 4.3 Å) between the protons of the benzoyl group and the inorganic sulfur atom of the [4Fe-4S] cluster than the corresponding ones of 1 (av. 6.2 Å). These results indicate the C–H···S interaction between the protons of the benzoyl group and the sulfur atom of the [4Fe-4S] cluster. The [Fe4S4(SAr)4]2−/[Fe4S4(SAr)4]3−redox potential for 1 and 4 are −0.86 and −0.65 V, respectively. The difference between 1 and 4 is Δ0.21 V. This is larger than the value Δ0.11 V between [Fe4S4(S-2-t-BuCONHC6H4)4]2− (−0.91 V) and [Fe4S4{S-2,6-(t-BuCONH)2C6H3}4]2− (−0.80 V), considered to be the difference between singly and doubly NH···S hydrogen-bonded complexes. The redox potentials for 16 follow the trend of the Hammett σm values, showing that the aromatic ring of the benzoyl group interacts with the [4Fe-4S] cluster directly. A cooperative effect between the C–H···S interaction and the NH···S hydrogen bond is thus found to regulate the redox potential of the model complexes.
  • Hideaki Kanno, Takahiro Yano, Katsumi Sato, Shunji Utsuno, Junnosuke F ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1085-1091
    Published: 1997
    Released: June 13, 2006
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    New cobalt(III) complexes, [Co(N4)(bpdo)]3+ (N4 = (en)2, (tn)2, (NH3)4, and tren; bpdo = 2,2′-bipyridine 1,1′-dioxide) and [Co(en)2(rac-3,3′-Me2bpdo)]3+ (rac-3,3′-Me2bpdo = racemic3,3′-dimethyl-2,2′-bipyridine 1,1′-dioxide), were obtained, where tn and tren denote trimethylenediamine and 2,2′,2″-triaminotriethylamine, respectively. The [Co(en or tn)2(bpdo)]3+ and [Co(en)2(rac-3,3′-Me2bpdo)]3+ complexes form only one of two possible racemic pairs of diastereomers, which were resolved by SP-Sephadex column chromatography. Each pair of these complexes was assigned to have a lel(Δ(λ), Λ(δ)) structure on the basis of the 13C NMR and circular dichroism spectra, and the absolute configuration of optically active free 3,3′-Me2bpdo ligand recovered from the resolved complex. The tetraammine and tren complexes were resolved into a pair of enantiomers by a chemical method, but rapidly racemized in water with the rate of 7.33 × 10−3 s−1 and 1.16 × 10−3 s−1, respectively, at 10.0 °C. An intramolecular conformational inversion of the skew bpdo chelate ring (δ λ) was proposed for the racemization.
  • Tadaharu Ueda, Ken-ichi Sano, Sadayuki Himeno, Toshitaka Hori
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1093-1099
    Published: 1997
    Released: June 13, 2006
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    The reaction of Mo(VI) with PHO32− in acidic solution containing CH3COCH3 or CH3CN led to the formation of the previously unknown 15-molybdobis(phosphonate) complex. The addition of an excess of PHO32− caused 15-molybdobis(phosphonate) to transform into 16-molybdotetrakis(phosphonate) in the CH3COCH3–water system. In the CH3CN–water system, on the other hand, the spontaneous transformation of 15-molybdobis(phosphonate) into 12-molybdobis(phosphonate) occurred in the presence of an excess of PHO32− or at greater acidities; the latter complex was also formed in aqueous media. The yellow heteropolyanions underwent electrochemical reductions, yielding mixed-valence blue species.
  • Tae Bo Sim, Nung Min Yoon
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1101-1107
    Published: 1997
    Released: June 13, 2006
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    Reducing characteristics of borohydride exchange resin (BER)–CuSO4 (cat.) were studied in methanol at room temperature. Carbon–carbon double bonds conjugated with benzene or carbonyl group were more rapidly reduced than was the case with isolated double bonds. Carbonyl groups were readily reduced, whereas esters and amides were inert, and nitriles were slowly reduced. High chemoselectivity was also observed in halide reductions: p-bromochlorobenzene and p-bromoiodobenzene were reduced quantitatively to chlorobenzene and bromobenzene, respectively. Aliphatic epoxides were inert to this reagent; however, styrene oxide derivatives were readily reduced to the corresponding deoxygenated products. Aliphatic azides were reduced slowly during 6 h, whereas phenyl azide was transformed to aniline in 1 h. Nitrocyclohexane was reduced at room temperature, but nitrobenzene, nitrosobenzene, azobenzene, and azoxybenzene required an elevated temperature (65 °C) for rapid reductions (1 h). Similarly, N,N-dimethylaniline N-oxide was reduced at room temperature, whereas pyridine N-oxide required refluxing. Finally, among the sulfur compounds tested, only diphenyl disulfide was reduced readily, and sulfide, aliphatic disulfide, sulfoxide, sulfone, and tosylate were inert to this reducing system.
  • Takashi Katoh, Keizo Ogawa, Yoshio Inagaki, Renji Okazaki
    1997 Volume 70 Issue 5 Pages 1109-1114
    Published: 1997
    Released: June 13, 2006
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    Perpendicularly-linked pentamethinestreptocyanine dimers (1) in which the two cyanine moieties are linked at the center carbon atoms of the methine chains were prepared. The absorption spectra of 1 in solution showed two peaks at 446 and 406 nm, which are attributed to the splitting of the HOMO levels through spiro-conjugation between the two cyanine moieties, as calculated from the INDO/S-CI method. The reduction potential of 1 positively shifted with respect to that of the corresponding monomer (2). The oxidation polarogram of 1 showed two waves, with the first potential negatively shifting compared to that of 2.
  • Ken-ichi Sugiura, Gelii Ponomarev, Satoshi Okubo, Akio Tajiri, Yoshite ...
    1997 Volume 70 Issue 5 Pages 1115-1123
    Published: 1997
    Released: June 13, 2006
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    5,5′-Ethylenebis(octaethylporphyrin) 1 and its metallocomplexes with various combination of metals (Zn, Cu, and Ni) 210 were prepared. On the basis of 1H and 13C NMR as well as MCD spectra, it was concluded that interactions between the two intramolecular porphyrins become attractive when at least one of the two rings is converted to zinc porphyrin. The phenomenon was explained by dipole–dipole interaction arising from the large polarization in Zn complexes.
  • Shigeki Kawabata, Iwao Yamazaki, Yoshinobu Nishimura
    1997 Volume 70 Issue 5 Pages 1125-1133
    Published: 1997
    Released: June 13, 2006
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    A series of anthrylpolyynes (α-anthryl-ω-(formylphenyl)polyynes) and anthrylpolyynylporphyrins (5-[(anthrylpolyynyl)phenyl]porphyrins) have been synthesized, and their photochemical properties and photoinitiated intramolecular excitation energy transfer from anthracene to porphyrin were studied by picosecond time-resolved fluorescence spectroscopy. Although anthrylpolyynes have strong fluorescence emission and fluorescence high quantum yield, anthrylpolyynylporphyrins, in which porphyrin links to the other side of polyyne, show only typical fluorescence emission of porphyrin and almost no fluorescence emission in the spectral region of anthrylpolyynes. The excitation of anthryl substituent brings about an increase in the fluorescence emission of porphyrin on the picosecond time scale. The mechanism of quantitative energy transfer from the anthryl moiety to the porphyrin is discussed on the basis of the photochemical properties of the component molecules.
  • Yoshihito Kayaki, Isao Shimizu, Akio Yamamoto
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1135-1140
    Published: 1997
    Released: June 13, 2006
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    Treatment of neutral monoorganobis(trimethylphosphine)palladium(II) halide complexes, trans-[PdR(X)(L)2] 1 (R = Me, Et, or Ph group, X = halide ligand, L = trimethylphosphine), with an equimolar amount of a silver salt such as AgBF4 usually gives cationic monoorganobis(trimethylphosphine) palladium(II) complexes, trans-[PdR(s)L2]BF4 (s = solvent) 2. But employment of an excess amount of the silver salt in the reaction with 1 or treatment of 2 with an additional amount of the silver salt yields a cationic monoorganopalladium(II) complex coordinated with one PMe3 ligand, cis-[PdR(L)(s)2]+3 by removing one of the PMe3 ligands in 2. The cationic mono-phosphine complex 3 can be also prepared by addition of an equimolar amount of a silver salt to the neutral dinuclear Cl-bridged, monophosphine complex [PdMe(μ-Cl)(PMe3)]25. The cis configuration of 3 was supported by comparison of the NMR spectra with those of cationic, cyclooctadiene (COD)-coordinated monomethylmono(trimethylphosphine)palladium complex, cis-[PdMe(PMe3)(cod)]BF4, 6. Complex 6 was prepared by two routes, by treatment of 3 with COD and by reaction of [PdMe(Cl)(cod)] 7 with an equimolar amount of AgBF4 followed by addition of an equimolar amount of PMe3. The cationic mono-phosphine complex 3 having one PMe3 ligand shows greater reactivity for the CO insertion than the bis-phosphine complex 2.
  • Yoshihito Kayaki, Isao Shimizu, Akio Yamamoto
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1141-1147
    Published: 1997
    Released: June 13, 2006
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    New dimethylpalladium complexes having alkyl and aryl phosphites as the supporting ligands, cis-[PdMe2{P(OR)3}2] (R = Me, 1a; Ph, 1b), have been prepared by two routes, (1) by the reaction of [Pd(acac)2] with [AlMe2(OEt)] in the presence of the phosphite ligands, and (2) by the ligand exchange reaction of [PdMe2(cod)] (COD = 1,5-cyclooctadiene) with two molar amounts of the phosphites. Monomethylpalladium chloride complexes, [PdMe(Cl){P(OR)3}2] (R = Me, 2a; Ph, 2b; Pri, 2c) have been prepared by ligand exchange reaction of [PdMe(Cl)(cod)] with two molar amounts of the phosphites, whereas [PdMe(OAc){P(OR)3}2] (R = Me, 3a; Ph, 3b) has been synthesized by treatment of 1 with acetic acid. Strong influence of the coordinated phosphite ligand on the cis or trans configuration of the monomethylpalladium complexes was observed, the results being in contrast with those of complexes having the trimethylphosphine ligands that give preferentially trans complexes. Removal of the chloride ligand in 2 with an equimolar amount of AgBF4 or treatment of the dimethylpalladium complex 1 with HBF4 in the expectation of obtaining a bis(phosphite)-coordinated complex led to formation of a mixture of the tris(phosphite) complex, [PdMe{P(OR)3}3]+BF4 and the mono-phosphite complex [PdMe{P(OR)3}(s)2]+BF4 (s = solvent), presumably through the rapid disproportionation of an unstable intermediate [PdMe{P(OR)3}2(s)]+BF4.
  • Masao Shiozaki, Masami Arai, Wallace M. Macindoe, Takashi Mochizuki, T ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1149-1161
    Published: 1997
    Released: June 13, 2006
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    Six GLA-60 positional isomers (8, 14, 14′, 20, 26, and 26′) were synthesized to investigate their biological activities. Compound 8 exhibited potent agonistic activity, while compounds 26 and 26′ exhibited slight agonistic activity on TNFα production toward human monoblastic U937 cells. TNFα production (% control; 10 ng ml−1 of LPS = 100) of compound 8 in the concentration of 10 μM was 611, and that of lipid A in the same concentration was 651. In contrast, the difluorinated compounds 14, 14′, and 20 showed little agonistic activity on TNFα production. And neither compound 8 nor compounds 26 and 26′ showed antagonistic activity. On the other hand, the difluorinated compounds 14, 14′, and 20 showed potent antagonistic activity, and inhibited the LPS-induced TNFα production dose-dependently. Compound 14′ (10 μM) inhibited in excess of 80% of the LPS-induced TNFα production.
  • Masaaki Mishima, Hiroki Inoue, Mizue Fujio, Yuho Tsuno
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1163-1169
    Published: 1997
    Released: June 13, 2006
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    The relative stabilities of 1-aryl-2,2,2-trifluoroethyl cations were determined based on the chloride ion-transfer equilibria in the gas phase. An application of the Yukawa–Tsuno equation to this substituent effect on the equilibrium constants gave a remarkably larger r+ of 1.53 and a ρ of −10.6, supporting our previous conclusion that the highly electron-deficient benzylic carbocation systems are characterized by extremely high resonance demands. This r+ value, furthermore, conformed a linear relationship between the r+ value and the relative stability of the unsubstituted member of the respective benzylic carbocations, clearly demonstrating a continuous spectrum of varying resonance demands characteristic of the stabilities of carbocations. The π-delocalization of the positive charge into the aryl π-system increases with the destabilization of a carbocation by the α-substituent(s) linked to the central carbon. In addition, the r+ value of 1.53 for 1-aryl-2,2,2-trifluoroethyl cations was found to be in complete agreement with that for the solvolysis of 1-aryl-2,2,2-trifluoroethyl tosylates in 80% aq acetone. This reveals that the r+ value observed for this solvolysis must be the intrinsic resonance demand of a highly electron-deficient cationic transition state in the SN1 ionizing process. The identity of the r+ value was consistent with our previous observation for other benzylic carbocation systems, indicating that the degree of the π-delocalization of the positive charge is identical between the cationic transition state and an intermediate cation for all benzylic systems, which cover a wide range of reactivity and stability of the carbocation. This leads us to the conclusion that the geometry of the transition state in the ionizing process of the SN1 solvolysis, which is a highly endothermic reaction, closely resembles the high-energy product, an intermediate cation.
  • Shinji Takeoka, Takeru Ohgushi, Hiroyuki Nishide, Eishun Tsuchida
    1997 Volume 70 Issue 5 Pages 1171-1178
    Published: 1997
    Released: June 13, 2006
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    The hemoglobin vesicle (HbV) has a cellular structure which encapsulates concentrated Hb in the inner aqueous phase of a phospholipid bilayer vesicle. Hb is gradually autoxidized to methemoglobin (metHb), which can not bind oxygen during oxygen transport under physiological conditions. In order to reduce metHb in HbV, we evaluated the reduction of metHb by electron transfer across the bilayer membrane of HbV from a reductant added to the outer aqueous phase. Water-soluble methylene blue (MB) and hydrophobic ubiquinone 10 (UQ) were selected as electron mediators. Under a nitrogen atmosphere, the addition of the reduced form nicotinamide-adenine dinucleotide (NADH) to the outer aqueous phase of UQ-incorporated HbV showed only a slow reduction rate for metHb. On the other hand, when MB and NADH were added under a nitrogen atmosphere to HbV containing 40% metHb, a rapid decrease in the metHb percentage was observed. The entire reaction was controlled by a reaction with NADH and MB in the outer aqueous phase. Under aerobic conditions, the decrease in the efficiency of the metHb reduction and rapid oxidation after reaching the minimal metHb percentage were observed. This was confirmed to be due to the influence of hydrogen peroxide; the decrease was prevented by the co-encapsulation of catalase.
  • Masaharu Tsuji, Masato Aizawa, Erika Oda, Yukio Nishimura
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1179-1183
    Published: 1997
    Released: June 13, 2006
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    The branching ratios of product ions for the reactions of CF3+ with PhX (X = F, Cl, Br, I) have been determined by using an ion-beam apparatus. The main reaction channels are electrophilic addition to a benzene ring, followed by HF and HX elimination, and X abstraction reaction leading to phenyl cation. Charge transfer reaction leading to the parent cation was found only for PhI with the lowest ionization potential. Semi-empirical MNDO calculations of heats of formation of various intermediates and products were carried out to explore possible reaction mechanisms.
  • Yasuhiro Nakano, Emiko Yamazaki, Hiroyuki Hanahata, Kunihiko Okajima, ...
    1997 Volume 70 Issue 5 Pages 1185-1192
    Published: 1997
    Released: June 13, 2006
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    An attempt was made to clarify the mechanism of a chain-extending reaction of NCO-terminated prepolymers in the synthesis of segmented poly(urethane–urea) using blocked ethylenediamine (EDA) with acetone (ACE). For this purpose, an ACE/EDA mixture was allowed to react with phenyl isocyanate (PhNCO) as a model of the prepolymer. The reaction of PhNCO with the ACE/EDA mixture, which was proved to contain ketimine and imidazolidine compounds by NMR measurements, gave 1,1′-ethylenebis[3-phenylurea] (M-Ur-1) as the main product; at the same time 1,3-diphenylurea (1,3-DPU) was assumed to be formed as a side-reaction product between PhNCO and H2O, inevitably existing in the mixture as the result of condensation. From a considerable increase in the yield of M-Ur-1 upon the addition of an excess amount of H2O to the reaction system, H2O was elucidated to participate in the acceleration of the main reaction, giving M-Ur-1 as well as in the side reaction, yielding 1,3-DPU. The excess H2O added to the system might preferentially facilitate the former reaction, rather than the latter.
  • Tomoshige Kobayashi, Shin-ya Yamamoto, Hiroshi Kato
    1997 Volume 70 Issue 5 Pages 1193-1197
    Published: 1997
    Released: June 13, 2006
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    A series of 1,4-diacetyl-1,4-dihydropyrazines fused with two bornene, cyclopentene, and cyclohexene rings were prepared by the reduction of the corresponding pyrazines with zinc powder in the presence of acetic anhydride. Cyclic voltammetry measurements revealed that the oxidation potentials of the dihydropyrazines decrease in the order of cyclohexene-, bornene-, and cyclopentene-fused derivatives. This trend is in harmony with that of the bathochromic shifts in their UV absorptions.
  • Kazuchika Ohta, Mitsuo Moriya, Mayumi Ikejima, Hiroshi Hasebe, Nagao K ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1199-1203
    Published: 1997
    Released: June 13, 2006
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    Bis[1,2-bis(3,4-di-n-alkoxyphenyl)ethanedione dioximato]palladium(II) complexes (abbreviated as [Pd{(CnO)4dpg}2]; n = 7—12) form gels in an over-concentrated n-hexane solution. We have developed a specific cell for X-ray diffraction in order to determine the gel structure. The gel has a two-dimensional hexagonal structure which is similar to the inverted hexagonal phase of lyotropic liquid crystals. The electronic spectra were measured for the gel and for a chloroform solution, which dose not form a gel. As a result, it has become apparent that a 4dz2–5pz intermolecular charge-transfer transition between the neighboring palladium ions is the main driving force of the gel formation. The circular dichroism and magnetic circular dichroism of the gel suggested that this complex has a stack of left-handed helicity. The complex also has a thermotropic liquid-crystalline state, as previously reported. Hence, these three kinds of states are closely related to each other in terms of the formation of molecular aggregates.
  • Takeshi Endo, Takashi Suzuki, Fumio Sanda, Toshikazu Takata
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 5 Pages 1205-1210
    Published: 1997
    Released: June 13, 2006
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    Acid-catalyzed reversible crosslinking–decrosslinking of polymers having spiro orthoester groups in the side chains was carried out. The copolymers obtained by the radical copolymerizations of 2-methylene-1,4,6-trioxaspiro[4.6]undecane with acrylonitrile, methyl, cyclohexyl, and 2-ethylhexyl acrylates were treated with trifluoroacetic acid (5 mol%) at −10 °C for 1 h in CH2Cl2 (4.2 M) to afford the crosslinked polymers in 69—99% yields. The crosslinked polymers were then treated with trifluoroacetic acid at a low concentration (0.1 M) in CH2Cl2 at room temperature for 1 h to give the original polymers in 55—99% yields. These results strongly support the conclusion that the acid-catalyzed reversible crosslinking–decrosslinking of the polymers possessing the spiro orthoester groups in the side chains could be constructed.
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