Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 66 , Issue 10
Showing 1-50 articles out of 61 articles from the selected issue
  • P. K. Biswas, S. C. Lahiri, B. P. Dey
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2785-2789
    Published: 1993
    Released: August 16, 2006
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    The effect of substitution on the solubility and dissociation constants for the reaction

    have been studied from the measurements of pH and solubilities of substituted benzoic acids in ethanol+water mixtures (0—100 wt%). The changes in the solubility values depend on the hydrophobic character and the dielectric constant of the solvent medium. The free energies of transfer for anions have been determined from the relation

    using the previously determined values of ΔGt°(H+). The results are discussed in the light of solute-solvent interactions.
  • Ryuji Shiozaki, Hideya Goto, Yoshiya Kera
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2790-2796
    Published: 1993
    Released: August 16, 2006
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    In the presence of the heteropolytungstolanthanate anion (Ce(IV)W10O36−8, Nd(III)W10O36−9, and Sm(III)W10O36−9; LnW10) the kinetic behaviors of hydrogen peroxide decomposition and cyclohexanol oxidation with H2O2 were investigated. In CeW10 the H2O2 decomposition rate tended to reach almost a limited value with increasing H2O2 concentration, while in NdW10 and SmW10 it decreased considerably after reaching the maximum value in high H2O2. The kinetic behavior of LnW10 was reasonably explained by a reaction scheme in which an intermediate species is initially formed (IS1) and then reacts further with H2O2 molecules to change the inactive species and, thus, to be removed from the catalytic cycle. Cyclohexanol was selectively oxidized with H2O2 to cyclohexanone according to the reaction order 0.6—0.8 on the H2O2 concentration until the high H2O2 region in the presence of all LnW10. The Arrhenius law concerning the overall rates of both reactions of H2O2 decomposition and cyclohexanol oxidation was maintained in any LnW10; further, a good compensation effect between the Arrhenius parameters, preexponential factor (log V0) and apparent activation energy (Eap), was found for both reactions in the series of LnW10. However, the empirical points concerning the log V0 vs. Eap plot in the oxidation alined in an inverse manner to those in H2O2 decomposition; that is, the order is CeW10 < SmW10 < NdW10 in the former and NdW10 < SmW10 < CeW10 in the latter. From this finding, both reactions were suggested to proceed via a common-intermediate species. Furthermore, it was elucidated that the more stable is the species, the more favorably are the alcohol molecules activated to the final products in the oxidation reaction.
  • Kiyoshi Kanamura, Zen-ichiro Takehara
    1993 Volume 66 Issue 10 Pages 2797-2803
    Published: 1993
    Released: August 16, 2006
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    The temperature and thermal stress distributions in two model cells for a tubular solid oxide fuel cell, which have a different thickness of the electrolyte, were calculated by the finite element method to demonstrate the effects of electrolyte thickness on the mechanical stability of fuel cells. When the cells were operated at a constant voltage, their energy conversion efficiency increased with decreasing thickness of the electrolyte. A larger amount of heat was generated in the cell having a thinner electrolyte, thus producing a larger thermal stress. These results indicates that an excellent preparation method for the highly ionic conductive electrolyte is essential to produce a fuel cell with high mechanical stability.
  • Takeshi Kawai, Kaoru Hamada, Kijiro Kon-No
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2804-2807
    Published: 1993
    Released: August 16, 2006
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    The limiting amounts of water solubilized by butyldodecyldimethylammonium bromide (BDDAB) in chlorobenzene increased rapidly at 0.01 mol kg−1 surfactant concentration at 30 °C. Using 1H NMR, fluorescence, and near infrared spectroscopic techniques, the solubilized states of water in the region obtained above 0.01 mol kg−1 were examined as a function of Rw ( = [H2O]/[BDDAB]) at various concentrations of surfactant. It was found from these spectral features that three types of water exist in varying proportions in the interior of reversed micelles, i.e., below Rw = 4 water is bound directly to the ionic head groups of the surfactant, in the range of Rw = 4—10 the succeeded water is held together with the hydrated ionic groups by hydrogen bonds, and above Rw = 10 bulk-like water is built up. These types of water could be discussed in connection with the formation of reversed and swollen micelles or W/O microemulsions. Further, the minimum Rw required for the formation of swollen micelles and W/O microemulsion and the critical swollen micelles or W/O microemulsion concentration could be estimated.
  • Kiyofumi Murakami
    1993 Volume 66 Issue 10 Pages 2808-2813
    Published: 1993
    Released: August 16, 2006
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    The binding of monoanionic azo dyes (4-(2-hydroxy-1-naphtylazo)benzenesulfonate (Orange II) and 6-hydroxy-5-phenylazo-2-naphthalenesulfonate (Ponceau 4G)) and dianionic one (6-hydroxy-5-(4-sulfophenylazo)-2-naphthalenesulfonate (Sunset Yellow FCF)) to bovine serum albumin (BSA) at pH = 7.0 and 25 °C has been studied by equilibrium dialysis, spectrophotometry, and a temperature-jump method. The binding parameters for the monoanionic dyes were found to take quite similar values to each other. This shows that both of the dyes bind to BSA in essentially the same manner, irrespective of the difference in the position of the sulfonato group on the ligands. On the other hand, the data for the dianionic dye showed that the secondary sites, observed for the monoanionic dyes, almost completely disappeared, while the number and the binding constant for the primary sites were comparable. Kinetic data concerning the BSA–Sunset Yellow FCF system were found to be consistent with a scheme in which a bimolecular binding is followed by two isomerizations of the complex at the primary site. All of the equilibrium and rate constants for the scheme have been determined. A comparison of the results to those for other ligands has shown that the bimolecular association rate constant successively decreases with an increase in the number of anionic charges on the ligands. In the case of monoanionic dyes, however, the number of observed relaxations showed a tendency to increase with an increase in the number of bound dyes on the secondary sites. On the basis of these results, the detailed binding mechanism is discussed from the view point of the relation between the specificity of ligand-binding and the number of charges on the ligand.
  • Akiko Okumura, Midori Fushimi, Masako Yamamoto
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2814-2826
    Published: 1993
    Released: August 16, 2006
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    The rates of the oxygen-exchange reactions of methyl- and butylarsonic acids and dimethylarsinic acid with solvent water were measured in the pH range below 6, and at temperatures between 50 and 90 °C, by using the 17O NMR line-broadening technique. For methylarsonic acid, the rate RMAA is expressed by the following rate law: RMAA = kh1[H+][H2A] + k1[H2A] + kh2[H+][H2A]2 + k2[H2A]2 + k3[H2A][HA], where H2A and HA designate CH3AsO3H2 and CH3AsO3H, respectively. For butylarsonic acid, the rate law is expressed as: RBAA = kh1[H+][n–C4H9AsO3H2]. For dimethylarsinic acid, its conjugated acid is involved in the rate law as: RCAA = kh1′[(CH3)2AsO2H2+] + khh1′[H+][(CH3)2AsO2H2+]. The exchange rates of methyl- and butylarsonic acids and dimethylarsinic acid (50—90 °C) were analyzed in terms of the respective rate law to obtain the values of the rate constants involved in the rate laws. The activation parameters of these rate constants were obtained; for both the first- and second-order rate constants, the activation energies are characteristic of their small values (from 45 to 20 kJ mol−1), while the activation entropies have large negative values, which are found in the range between −92 and −145 J K−1 mol−1.
  • Yoshihisa Matsui, Eiji Tanemura, Tohoru Nonomura
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2827-2831
    Published: 1993
    Released: August 16, 2006
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    Heptakis(6-butylamino-6-deoxy)-β-cyclodextrin (2) forms 1 : 1 complexes with several inorganic anions in 0.10 mol dm−3 HCl or DCl at 25 °C. The binding constant for a complex of 2 with the SO42− ion was remarkably larger than those for complexes of 2 with univalent anions and those for complexes of the α- (1) and γ-cyclodextrin (3) analogs with the SO42− ion. The circular arrangement of the protonated amino groups in 2 may be advantageous for electrostatic interactions with the bivalent anion.
  • Akira Miyazaki, Akira Izuoka, Tadashi Sugawara
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2832-2839
    Published: 1993
    Released: August 16, 2006
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    Crystal structures of three Ni(dmit)2 salts, whose counter cations ((2-methoxyethyl)ammonium, morpholinium, N-methylmorpholinium) consist of both hydrogen-bond donating and accepting sites, are reported. Within these salts, the Ni(dmit)2 columns are structurally modulated by intermolecular hydrogen bonds between the –NH+ group of the cation and the =S group of the dmit ligand. The alignment and the overlapping modes of Ni(dmit)2 molecules are found to be mainly governed by the hydrogen bonding pattern.
  • Masayasu Iida, Yasuko Miyagawa, Sachiko Kohri, Yuhko Ikemoto
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2840-2846
    Published: 1993
    Released: August 16, 2006
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    59Co NMR spectroscopy was used to study the interactions of cationic or neutral octahedral cobalt(III) complexes such as [Co(NH3)6]3+, [Co(en)3]3+ (en = ethylenediamine), [Co(NO2)(NH3)5]2+, and [Co(acac)3] (acac = acetylacetonato) with surfactants in their nematic liquid crystalline solutions. The specific interactions of the complexes with the surfactants were studied in a replacement of one surfactant by another that had a different polar group. The extent of the binding of these complexes was monitored through the 59Co quadrupole splittings. The relationship between the extent of the binding and the magnitude of the quadrupole splitting did not hold when comparing the three cationic complexes. A comparison between the potassium dodecanoate (KDodec)/tetradecyl (or decyl)trimethylammonium bromide (TDTMABr or DTMABr) and the cesium N-dodecanoyl-L-alaninate (CsDDA)/tetradecyltrimethylammonium bromide (TDTMABr) mixed surfactant systems in the interaction with [Co(NH3)6]3+ and [Co(en)3]3+ complexes showed that these complexes bind to the alaninate polar group through a weakly interacting site in the range of the intermediate composition of the mixed surfactants; such a kind of the binding was negligible or smaller in the dodecanoate system. [Co(acac)3] complex was solubilized to liquid crystals and the interactions with the surfactant depended on their polar groups in spite of the electric neutrality of the complex.
  • Hideki Saitoh, Kazuya Saito, Yasuhisa Yamamura, Haruo Matsuyama, Koich ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2847-2853
    Published: 1993
    Released: August 16, 2006
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    4,4″-Difluoro-p-terphenyl and 4,4″′-difluoro-p-quaterphenyl were synthesized and their crystal structures were determined at room temperature. These are isostructural to p-terphenyl and p-quaterphenyl, respectively. Some “disorder” in the inner benzene ring orientation was detected and resolved by the split-atom method. A rigid-body librational analysis of each benzene ring around the long molecular axis was performed. A rough estimate of the barrier height of the planar conformation for 4,4″-difluoro-p-terphenyl was obtained as being about 1 kJ mol−1. The results are compared with the properties of p-terphenyl and p-quaterphenyl, and the effect of fluorine-substitution on the molecular properties is discussed in relation to the low-temperature phase transitions.
  • Omar Ahmed, Shunzo Yamamoto, Yoshimi Sueishi, Norio Nishimura
    1993 Volume 66 Issue 10 Pages 2854-2857
    Published: 1993
    Released: August 16, 2006
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    The cadmium (53P1)-sensitized luminescence of some aliphatic compounds which have two functional groups have been studied under the conditions of steady-state illumination at temperatures between 473 and 573 K. It was found that 1,2-dimethoxyethane (DMOE), 2-methoxyethylamine (2-MOEA), and 3-methoxypropylamine (3-MOPA) have two emission bands (wavelengths at the peaks of these bands are about 400 and 455 nm for DMOE and about 460 and 500 nm for 2-MOEA and 3-MOPA), while 2-aminoethanol (2-AEA) and 3-amino-1-propanol (3-APA) do not have any emission band. These two bands were assigned to two kinds of 1 : 1 exciplex (cyclic and acyclic ones) between an excited cadmium atom and a substrate molecule. From the temperature dependence of the emission intensity ratios of these bands, the enthalpy changes (ΔH°) of the equilibrium between two exciplexes were evaluated. The values of ΔH° are correlated to the energy differences between the wavelengths of two emission bands.
  • Teruhisa Komura, Takahiro Nakanori, Koshin Takahashi
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2858-2863
    Published: 1993
    Released: August 16, 2006
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    The electrical behavior of the Nb2O5 electrode in Na2SO4 solutions was characterized by the impedance spectra. The pH dependence of the flat band potential could be explained in terms of the acid-dissociating equilibrium of hydroxyl groups on the oxide surface. The plot of equilibrium potential of the oxide vs. pH gave a straight line with a slope of −0.06 V. The equilibrium potential became monotonously more negative with increasing extent of the reduction of the oxide. The cyclic voltammograms and chronopotentiograms of the partially reduced oxide indicated that the diffusion of an electroactive species in the oxide controlled the rate of the electrode process. These results suggest that HxNbO2.5 or NbO2.5−x(OH)x can be formed by the reduction of the oxide. The conductivities of the oxide increased about two orders of magnitude by the insertion of a small amount of hydrogen. In conclusion, a blue coloration of the oxide can occur as a result of the diffusion of H+ from the electrolyte into the Nb2O5 lattice and a simultaneous injection of electrons to d-block bands of Nb in the energy band model.
  • Masaharu Tsuji, Ken-ichi Matsumura, Tsuyoshi Funatsu, Yukio Nishimura, ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2864-2870
    Published: 1993
    Released: August 16, 2006
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    Rate constants and product ion distributions have been determined for thermal energy reactions of CO2+ with n-C4H10 and i-C4H10 by using an ion-beam apparatus. The total rate constants are (9.8 ± 2.0) × 10−10 and (1.0 ± 0.2) × 10−9 cm3 s−1 for n-C4H10 and i-C4H10, respectively. These values amount to about 75% of the collision rate constants estimated from the Langevin theory. C4H9+, C3Hn+ (n = 5—7), and C2Hn+ (n = 3—5) are produced from n-C4H10 with branching ratios of 6, 56, and 38%, while C4H9+ and C3Hn+ (n = 5—7) are formed from i-C4H10 with branching ratios of 7 and 93%, respectively. The lack of C2Hn+ fragments from i-C4H10 is attributed to a low probability of significant rearrangement of chemical bonds for the formation of the C2Hn+ fragments. The product ion distribution in the CO2+/n-C4H10 reaction is in good agreement with that predicted from the fragmentation pattern of n-C4H10+ at 13.78 eV, indicating that the CO2+/n-C4H10 reaction proceeds through a near-resonant charge transfer without momentum transfer.
  • Kozo Inuzuka, Akira Fujimoto, Hiroshi Ito
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2871-2876
    Published: 1993
    Released: August 16, 2006
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    The band assignments of the IR spectrum of 1-methyl-2(1H)-pyridinimine in solution were carried out with the normal coordinate treatment by the ab initio 6-31G method. The IR spectrum of the compound is characterized by three prominent strong absorption bands in the 1700 to 1500 cm−1 region. These three bands are mainly attributed to the stretching modes of the C=C bonds of the ring and the C=N group. All another bands are relatively weak compared with the intensities of these bands. The normal coordinate treatment suggests that 1-methyl-2(1H)-pyridinimine has three out-of-plane fundamental bands in the frequency region lower than the lowest fundamental band of pyridine. The calculated lowest fundamental band is near 129 cm−1. It was assigned to the twisting mode of the CH3 group. The second and third lowest bands correspond to the twisting vibration of the CH3 group and the out-of-plane bending vibration of the ring framework. This suggests that the ring framework of 1-methyl-2(1H)-pyridinimine may be more flexible than that of pyridine. The vibrational features of the IR spectrum of 1-methyl-2(1H)-pyridinimine are similar to that of 1-methyl-2-pyridone. In the liquid state, 1-methyl-2(1H)-pyridinimine forms an inter-molecular hydrogen bond between the imino groups.
  • Hideaki Kita, Yunzhi Gao, Shen Ye, Katsuaki Shimazu
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2877-2882
    Published: 1993
    Released: August 16, 2006
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    The hydrogen evolution and ionization reactions were studied on Pt single crystal electrodes in N2 or H2 saturated, acidic solutions. The hydrogen evolution reaction was structure insensitive and the ionization reaction was structure dependent. The Tafel constants of the respective reactions, and , and the reaction orders, and , with respect to proton, did not satisfy the relationships, + = 2 and = −2, deduced by the rate-determining step which is the same for the hydrogen evolution and ionization reactions; The results were, + ≈ 4 and ≈ −4. These suggest that the rate-determining steps is different for the evolution and ionization reactions in acidic solutions. A tentative model for the reaction routes was proposed.
  • Robert Kingsford-Adaboh, Eiichi Hayashi, Masao Haisa, Setsuo Kashino
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2883-2888
    Published: 1993
    Released: August 16, 2006
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    The crystal structures of racemic form of isoprenaline hydrochloride (I) and (S)-isoprenaline hydrogen (2R,3R)-tartrate (II) were determined by X-ray diffraction method. Among the related compounds I has the least extended phenethylamine chain with a gauchegauche conformation. The side chain of II has the usually observed perpendicular-trans conformation. The conformations observed for I and II are consistent with the intermolecular hydrogen bonding. The observed conformations are close to either a global or local minimum estimated by MMP2.
  • Kazumasa Harada
    1993 Volume 66 Issue 10 Pages 2889-2899
    Published: 1993
    Released: August 16, 2006
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    Separations of geometrical isomers of the title complexes were carried out by a column chromatographic method. All three isomers of mer-, sym-fac-, and unsym-fac-[Rh(dien)2]3+ complexes were isolated. The only mer-isomer of the [Ir(dien)2]3+ complex was isolated, although trace fac-isomers were detected. Although the synthesis of a new [Rh(dpt)2]3+ (dpt = bis(3–aminopropyl)amine) complex was successful, that of [Ir(dpt)2]3+ was not. The only mer-[Rh(dpt)2]3+ isomer was obtained. These complexes were characterized by spectroscopic methods. In each case, the obtained unsym-fac- and mer-isomer were resolved in their antipodes. The crystal structures of three complexes were determined by an X-ray diffraction method. The crystal data are: for sym-fac-[Rh(dien)2]Br3, monoclinic, C2/c, a = 14.803(5), b = 9.102(3), c = 13.989(6) Å, β = 118.25(3)°, Z = 4, R = 0.0478; for mer-[Rh(dpt)2]Cl(ClO4)2, monoclinic, P21/a, a = 18.711(6), b = 12.942(5), c = 9.714(2) Å, β = 103.34(3)°, Z = 4, R = 0.0275; for mer-[Ir(dien)2] (ClO4)3·2H2O, orthorhombic, Aba2, a = 15.283(9), b = 14.736(4), c = 10.411(3) Å, Z = 4, R = 0.0341. The formation ratio of the isomers for the [Rh(dien)2]3+ complex is different from the known ratio for cobalt(III) analogs; this can be attributed to a difference in the M–N bond length based on a molecular mechanics calculation.
  • Masaru Kimura, Miyuki Sato, Tomoko Murase, Keiichi Tsukahara
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2900-2906
    Published: 1993
    Released: August 16, 2006
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    The kinetics of the reaction between nitrous acid and iodide ion were studied in the presence of molecular oxygen (O2) in an acid solution (pH 1.9—3.1); much larger amounts of the triiodide ion than expected from the amounts of nitrous acid were formed under conditions of the iodide ion in excess over nitrous acid. The initial rates for the formation of I2 and I3 increased proportionally with increasing both the O2 and nitrous acid contents, and increased greatly with decreasing the pH in the solution. The reaction rate was also decreased by bubbling either air or O2 through the reacting solution, depending on the bubbling velocity. A chain mechanism is proposed to account for the results obtained in the dark: 2HNO2 + 2I + 2H+ → 2NO + I2 + 2H2O; 2NO + O2 → 2NO2; 2NO2 N2O4; N2O4 + 2I + 2H+ → 2HNO2 + I2; I2 + I I3. The rate-determining step was the reaction of NO with O2. The addition of trace amounts of copper(II) or iron(II) ion enhanced the formation of I2 and I3 due to the occurrence of reactions of I with the metal ions. Such an acceleration effect by the metal ions, however, could be diminished by the addition of ethylenediaminetetraacetic acid. Although the rate of the reaction of HNO2 with I was not greatly changed by the irradiation of visible light during the initial period of reaction, it was greatly accelerated after some formation of I2 and I3, being dependent on not only the light intensity, but also on the concentrations of H+ and I ions. The effects of the metal ions as well as visible light are also accounted for by the above-mentioned mechanism.
  • Hidefumi Sakamoto, Hiroki Goto, Makoto Yokoshima, Makoto Dobashi, Juni ...
    1993 Volume 66 Issue 10 Pages 2907-2914
    Published: 1993
    Released: August 16, 2006
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    Four types of benzo-15-crown-5 and benzo-18-crown-6 derivatives bearing a substituted hydrazone moiety as a proton-dissociable chromogenic group were synthesized and the solvent extraction behaviors of these compounds for alkali metal ions were evaluated spectrophotometrically. Benzo-15-crown-5 and -18-crown-6 hydrazones with 2,4-dinitro-6-(trifluoromethyl)phenyl or 2,6-dinitro-4-(trifluoromethyl)phenyl groups extracted alkali metal ions predominantly as 2 : 1 and 1 : 1 (crown ether : metal ion) complexes, respectively, from an aqueous alkaline solution into 1,2-dichloroethane and these ligands exhibited high K+-selectivity. The composition of the extracted species and the K+-selectivity depended on the polarity of the extraction solvent used. In particular, 2 : 2 complexes of several alkali metal ions with benzo-15-crown-5 and -18-crown-6 hydrazones bearing a 2,4-dinitro-6-(trifluoromethyl)phenyl group were readily extracted from an aqueous solution into chloroform.
  • Katsutoshi Inoue, Yoshinari Baba, Kazuharu Yoshizuka
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2915-2921
    Published: 1993
    Released: August 16, 2006
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    A fundamental investigation on the adsorption behavior of metal ions on chitosan from aqueous ammonium nitrate and hydrochloric acid solutions was conducted by batch-wise examining the effects by various factors: the pH, concentrations of ammonium nitrate and hydrochloric acid, and initial metal concentration on the amount of metals adsorbed. In order to prevent the dissolution loss of chitosan into an acidic aqueous solution, crosslinked copper(II)-complexed chitosan was prepared and its adsorption behavior was compared with that of the original chitosan. The amount of adsorption, not only of metal ions, but also of the hydrogen ion, was decreased by crosslinking in the adsorption from an ammonium nitrate solution. The decrease, however, was least for copper(II), compared with the other divalent metal ions examined: oxovanadium(II), zinc(II), nickel(II), and cobalt(II). It was considered that this result may be attributable to the “template” effect by the copper(II) ion, which was employed during crosslinking in order to protect the active adsorption site of chitosan from an attack by a crosslinking reagent. It was found that chitosan has an excellent loading capacity and a selectivity much greater than the commercial iminodiacetic acid type of chelating resin. A qualitative discussion is given concerning the excellent adsorption behavior. Contrary to the case of adsorption from an aqueous ammonium nitrate solution, no significant decreases in the distribution ratios were observed between the crosslinked copper(II)-complexed chitosan and the original chitosan regarding the adsorption of palladium(II) and platinum(IV) from hydrochloric acid.
  • Sushama Viladkar, Kamaluddin, Mala Nath
    1993 Volume 66 Issue 10 Pages 2922-2926
    Published: 1993
    Released: August 16, 2006
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    Simple zinc complexes of glycine, histidine, and cysteine are proposed as evolutionary models for hydrolytic enzymes. Catalytic activity of (amino acidato)zinc complexes has been studied towards hydrolysis of 4-nitrophenyl phosphate at 40 °C over the pH range 5.0—10.0 by monitoring release of p-nitrophenol at 405 nm. Detailed kinetic investigations on hydrolysis of ester catalyzed by zinc complexes are discussed through formation of (amino acidato)zinc-substrate complex. Mechanistic and evolutionary aspect of this study are discussed in relation to the esterase property of the zinc metalloenzymes.
  • Kamal Usef Sadek, Maghraby Ali Selim, Mohamed Hilmy Elnagdi, Hans Hart ...
    1993 Volume 66 Issue 10 Pages 2927-2930
    Published: 1993
    Released: August 16, 2006
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    The synthesis of several new polyfunctionally substituted fused pyrazoles via reaction of 5-amino-3-methylthio-1H-pyrazole-4-carbonitrile (1) with different reagents is described.
  • Toshio Eiki, Shin-ichi Negishi, Mitsunori Izumi, Naoko Ishida, Hiroshi ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2931-2935
    Published: 1993
    Released: August 16, 2006
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    In order to obtain insight into the selectivity of Mg2+ at the site of bond cleavage of P–O and S–O of the P–O–S linkage, metal ion-promoted alcoholyses of phenyl phosphatosulfate were studied. Mg2+ quantitatively promoted P–O bond cleavage in the methanolysis, but mixed cleavage of the P–O bond, which occurred partly due to hydrolysis by trace water and the S–O bond in the reaction of ethanol, 1- or 2-propanol. The ratio of the S–O bond cleavage against the mixed cleavage increased in a order EtOH (11.5%) < n–PrOH (13.3%) < i–PrOH (29.0%). On the other hand, Ca2+ and Zn2+ promoted selective P–O and S–O bond cleavage, respectively, in the reaction of 2-propanol as well as methanolysis.The medium-dependent change in the selectivity of Mg2+ at the site of bond cleavage was discussed.
  • Ramadan Mekheimer, Essam Kh. Ahmed, Ahmed F. Khattab
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2936-2940
    Published: 1993
    Released: August 16, 2006
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    Novel nucleophilic substitution in quinoline system utilizing 2-chloro-4-piperidino-3-quinolinecarbonitrile (1) and 4-piperidino-2-oxo-1,2-dihydro-3-quinolinecarbonitrile (2) was reported. Some new quinolinones and pyrazolo[4,3-c]quinolines were synthesized.
  • Kimio Shindo, Hidetsugu Wakabayashi, Sumio Ishikawa, Tetsuo Nozoe
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2941-2948
    Published: 1993
    Released: August 16, 2006
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    The reactions of benzo[b]cyclohept[e][1,4]oxazine (9) with a 1.2 equivalent of α,ω-alkanediamines (2, n = 4—12) in ethanol at 80 °C afforded tropocoronands (5, n,n′ = 4,4—12,12) in a one-pot procedure and in high yields, while the reaction of 9 with an excess of 2 mainly gave tropopodands 12 (n,n′ = 4,4—6,6). The reactions of 9 with short-chain diamines 2 (n = 2,3) yielded bicyclic pyrazino or diazepino compounds as the main products. The reaction of 9 with ω-amino alcohol afforded the corresponding dihydroxy podands 23. The predicted pathways of the reaction of 9 with 2 were experimentally confirmed.
  • Yumiko Takagi, Toshiyuki Itoh
    1993 Volume 66 Issue 10 Pages 2949-2953
    Published: 1993
    Released: August 16, 2006
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    Lipase-catalyzed enantioselective hydrolysis of esters of 4-hydroxyalkanenitriles was demonstrated for the first time. Efficient optical resolution was achieved when (±)-3-cyano-1-phenylpropyl 2-(phenylthio)acetate was hydrolyzed by lipase PS (Pseudomonas sp.).
  • Makoto Kigoshi, Keizo Sato, Etsuo Niki
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2954-2959
    Published: 1993
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    The dynamics of the chain initiation of the oxidations of lipids by hyponitrites were studied in organic homogeneous solution and in aqueous dispersions of micelles and liposomal membranes. Di-t-butyl and distearyl hyponitrites were used in order to examine the effect of bulkiness of the alkoxyl radicals in different reaction media. Both hyponitrites induced the free radical-mediated chain oxidations of methyl linoleate in homogeneous solution and in aqueous emulsions and also of soybean phosphatidylcholine liposomal membranes. In aqueous dispersions, these lipophilic hyponitrites generated free radicals in the lipid compartment and aqueous radical-scavenging antioxidants could not suppress the oxidations induced by these hyponitrites. The efficiency of chain initiation decreased in the order of homogeneous solution > micelles > liposomal membranes in accordance with increasing viscosity of the medium. It was also dependent on the size of alkoxyl radical and distearyl hyponitrites was less efficient than di-t-butyl hyponitrite in initiating the chain oxidation in all of the above reaction media.
  • Hitoshi Fujita, Kiminori Tokiwa, Katsuhide Sayama, Hiroyuki Mori, Masa ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2960-2964
    Published: 1993
    Released: August 16, 2006
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    To understand the photochemical basis of photodermatitis caused by 2,2′ : 5′,2″-terthiophene, photooxidation of squalene sensitized with 2,2′ : 5′,2″-terthiophene was studied with respect to mediation by singlet molecular oxygen, the activation energy, and the apparent quantum yield. Squalene was peroxidized in ethanol solution by irradiation with UV-A light in the presence of 2,2′ : 5′,2″-terthiophene and the related compound 2,2′-bithiophene. Involvement of singlet oxygen in the peroxidation was suggested on the basis of the suppressive effect of sodium azide and the enhancing effects of organic solvents which elongate the lifetime of singlet oxygen. The activation energy obtained, 11.2 kJ mol−1, was a reasonable value for oxidation of olefins by singlet oxygen. The quantum yields of peroxidation were estimated to 12.6 × 10−2 and 8.3 × 10−2 for photosensitization with 2,2′ : 5′,2″-terthiophene and 2,2′-bithiophene, respectively.
  • Yoshiro Nagai, Kenji Kobayashi, Hiroo Toi, Yasuhiro Aoyama
    1993 Volume 66 Issue 10 Pages 2965-2971
    Published: 1993
    Released: August 16, 2006
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    5-Indolylboronic acid (1) reversibly forms boronic esters with reducing sugars in water. The resulting boronates are stronger Lewis acids than the starting boronic acid in the deprotonation of water; pKa = 10 for 1 and < 7 for its sugar-boronates. Thus, at pH 9.0, there exists an experimentally-evaluable sugar-binding equilibrium between neutral trivalent acid 1 and anionic tetravalent ester thereof, which can be conveniently monitored by fluorescence or 11B NMR spectroscopy. A characteristic aspect of the present sugar-binding process is the notable selectivity of host 1 for oligosaccharides. The binding constants for maltodextrins (α-1,4-linked glucose oligomers) increase with increasing chain lengths or repetition numbers of the glucose unit. Such a chain length selectivity and those among stereoisomers and linkage isomers of disaccharides are discussed in terms of intracomplex oligosaccharide–indole interaction.
  • Yoshitomo Nagata, Satoru Kanuka, Takatoshi Kinoshita, Akira Takizawa, ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2972-2976
    Published: 1993
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    Interaction between the side-chain pyridyl ligands of an α-helical poly(Nω-2-pyridylmethyl-L-glutamine) (P2PG) and guest ligands such as tryptamine and D- and L-tryptophan (D- and L-Trp) within ternary Cu2+ complexes was investigated by absorption and circular dichroism (CD) spectroscopy in 2,2,2-trifluoroethanol solutions. The host complex species, Cu2+-one pyridyl-substituted side-chain (s-2PG) complexes (1 : 1 Cu2+-P2PG, [Cu2+]/[s–2PG] > 1.0) and Cu2+- two s-2PGs complexes (1 : 2 Cu2+-P2PG, [Cu2+]/[s–2PG] < 1.0), were prepared, using Cu2+ and P2PG depending on the Cu2+ ion concentration. All guest molecules could bind noncovalently to the 1 : 1 Cu2+-P2PG system, having the ligand sites of Cu2+ partly unfilled, to yield their ternary Cu2+ complexes. The respective ternary complexes had induced optical activities in the CD spectra and a charge-transfer band indicating ligand–ligand stacking interactions involving charge transfer between the coordinated s-2PG and the guest indole moieties around Cu2+. The CD spectral intensity was in the order tryptamine < D-Trp, L-Trp, which suggests that the coordination of both amino and carboxyl groups of Trp to Cu2+ is important for the regular arrangement of the ligands on the periphery of the α-helix backbone of P2PG. The differences in the CD spectra suggest that the indole rings of D- and L-Trp face in a direction opposite to that of the pyridyl ring of P2PG. D- and L-Trp could also bind the 1 : 2 Cu2+-P2PG host system, whose Cu2+ coordination sites are filled with s-2PGs, but the 1 : 2 Cu2+-P2PG did not yield the ternary complexes with tryptamine.
  • Kensaku Morihara, Sakurako Doi, Michie Takiguchi, Toyoshi Shimada
    1993 Volume 66 Issue 10 Pages 2977-2982
    Published: 1993
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    The authors’ imprinting procedures for “molecular footprint” catalytic cavities on a silica (alumina) gel surface were reinvestigated. The increases of temperature during the incorporation of aluminum ions into the silicate matrix and during the footprint-imprinting with a template remarkably affected the catalytic characteristics of the resulting cavities. A change from room temperature to 75—80 °C increased the catalytic specificities (kcat/Km) by a factor of nearly 50. The results also provided experimental proof for the speculated mechanism of footprint formation. That is, the imprinting comprises precedent Lewis acid site generation on a silicate surface and subsequent Lewis acid–template complexation. The resulting acid–template complexes give rise to the footprint cavities upon removal of the template.
  • Misao Umehara, Hiromi Honnami, Shinzaburo Hishida, Takashi Kawata, Shi ...
    1993 Volume 66 Issue 10 Pages 2983-2986
    Published: 1993
    Released: August 16, 2006
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    The five cis/trans isomers of C6–C8–C5 fused ring compound, tricyclo[9.4.0.04,8]pentadecane-2,9-dione were synthesized by photocycloaddition of decalin-1,3-dione to cyclopentene. The conformational analyses were carried out by MM2 and the results were compared with X-ray analyses. The eight-membered rings take predominantly boat-chair forms although those in C5–C8–C5 fused ring compounds exist in various conformations.
  • Atsuo Takeuchi, Hitoshi Komiya, Takehiro Tsutsumi, Yukihiko Hashimoto, ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 2987-2994
    Published: 1993
    Released: August 16, 2006
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    The photoreaction of 2,3-di[(E)-styryl]pyrazine derivatives was carried out in the crystalline state and in solution. Among them, 2,3-di(p-chlorostyryl)pyrazine and 2,3-di(p-cyanostyryl)pyrazine were photoreactive in the crystalline state and gave, upon photoirradiation, [2.2]orthocyclophanes in 76 and 58% yields, respectively. Such a topochemical photo-behavior was interpreted on the basis of X-ray crystallographic analyses of the crystals. The photoirradiation of 2,3-distyrylpyrazine in solution gave [2.2]orthocyclophane and anti head-to-tail type monocyclic dimer as the major products. The yields of the products varied depending on the solvent; with decreasing the polarity of the solvent, the yield of the cyclophane decreased, whereas the yield of the monocyclic dimer increased. In a similar manner, the photoirradiation of the other 2,3-distyrylpyrazine derivatives in acetonitrile/chloroform (10/1) or acetonitrile gave the corresponding [2.2]orthocyclophanes and monocyclic dimers, respectively, as major products through two types of excimers.
  • Koichi Narasaka, Noriyoshi Arai, Tatsuo Okauchi
    1993 Volume 66 Issue 10 Pages 2995-3003
    Published: 1993
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    2-Tributylstannyl-1,3-dithianes and 1-(tributylstannyl)alkyl sulfides are oxidized with ammonium hexanitratocerate(IV) or ferrocenium hexafluorophosphate to generate their cation radicals, which dissociate into the carbocations and tributylstannyl radical. The carbocations thus generated react with olefinic nucleophiles to afford the corresponding addition products in good yield.
  • Hironobu Hojo, Saburo Aimoto
    1993 Volume 66 Issue 10 Pages 3004-3008
    Published: 1993
    Released: August 16, 2006
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    Barnase, site-specifically labelled with two 13C atoms, was synthesized using partially protected peptide thioesters as building blocks. Four partially protected peptide segments (Boc–[Lys(Boc)19,27]–barnase(1—34)–SC(CH3)2CH2CO–Nle–NH2, iNoc–[Lys(Boc)39,49]–barnase(35—52)–SC(CH3)2CH2CO–Nle–NH2, iNoc–[Lys(Boc)62,66]–barnase(53—81)–SC(CH3)2CH2CO–Nle–NH2, [Lys(Boc)98,108]–barnase(82—110)) were successively condensed in the presence of silver ions and N-hydroxysuccinimide (HONSu). Finally, barnase with full ribonuclease activity was obtained in a yield of 11% based on the carboxyl terminal peptide segment.
  • Takeshi Hasegawa, Yoshiyuki Kuwatani, Hiroyuki Higuchi, Ikuo Ueda
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3009-3014
    Published: 1993
    Released: August 16, 2006
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    The cationic rearrangement of 1-bromo-4-[hydroxybis(4-methoxyphenyl)methyl]pentacyclo[4.3.0.02,5.03,8.04,7]nonane-9-spiro-2′-[1,3]dioxolane (1) in formic acid gave 4-bromo-1-formyloxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,6.03,9.04,8]decane-5-spiro-2′-[1,3]dioxolane in 27% yield along with 5-bromo-9-formyloxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,5.03,9.04,8]decane-6-spiro-2′-[1,3]dioxolane in 55% yield. The reaction of 1 with p-toluenesulfonic acid or hydrochloric acid in methanol also afforded 4-bromo-1-methoxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,6.03,9.04,8]decane-5-spiro-2′-[1,3]dioxolane together with 5-bromo-9-methoxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,5.03,9.04,8]decane-6-spiro-2′-[1,3]dioxolane. With respect to migration of the C4–C5 bond in the pentacyclo[4.3.0.02,5.03,8.04,7]nonane (homocubane) skeleton to pentacyclo[5.3.0.02,6.03,9.04,8]decane (D2h-bishmocubane), a rearrangement into the bishomocubane system in driven by a concomitant release of strain; also, the stability of the 4-homocubanemethyl cation intermediate may play an important role in determining the course of the cage expansion into the D2h-bishomocubane system. This reaction provides an attractive route for the synthesis of bishomocubane bridgehead alcohols and related compounds which are not easily accessible by other routes.
  • Mizue Fujio, Yasuyuki Maeda, Mutsuo Goto, Yoshihiro Saeki, Masaaki Mis ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3015-3020
    Published: 1993
    Released: August 16, 2006
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    The substituent effect on the acetolysis of 2,2-bis(substituted phenyl)ethyl p-toluenesulfonates at 90.10 °C can be described accurately in terms of the Yukawa–Tsuno (LArSR) relationship, giving a ρ value of −4.44 and an r value of 0.53. The substituent effect correlation of this system carrying two aryls is quite comparable to that of the 2-methyl-2-phenylpropyl system carrying a single aryl group, suggesting the close similarity in the structure of the transition states between the systems. The results can be reasonably accounted for on the basis of the accepted mechanism of this reaction, involving a rate-determining aryl-assisted transition state where only one aryl group of the two β-aryl groups participates.
  • Mizue Fujio, Yasuyuki Maeda, Mutsuo Goto, Yoshihiro Saeki, Masaaki Mis ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3021-3029
    Published: 1993
    Released: August 16, 2006
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    The substituent effect on the acetolysis of 2-phenyl-2-(substituted phenyl)ethyl p-toluenesulfonates had a nonlinear LArSR correlation and was explicable in terms of a competitive aryl-assisted mechanism involving the X-substituted phenyl-assisted () pathway and the unsubstituted phenyl-assisted () pathway. By the application of the iterative nonlinear least-squares method based on the LArSR Eq., the substituent effect on the overall kt was dissected into the best-fit kM correlation of ρM = −3.53 with rM = 0.60, and the kN correlation of ρN = −0.88 with σ0. The ρM and rM values for the effects of assisting aryl substituents are quite close to those of the 2-methyl-2-phenylpropyl system and the small ρN value with unexalted σ0 constant for the unassisting aryls is compatible to the remote β-aryl effect. The relative rates of competing pathways dissected based on the substituent effect analysis agreed completely with the ratio of respective aryl migration products determined by the 13C-tracer method. Exact rate-product correlation demonstrates that this system involves two discrete aryl-assisted pathways, and , which do not cross over.
  • Yoshihiko Watanabe, Tetsuo Yoneda, Tatsuya Okumura, Yoshio Ueno, Takes ...
    1993 Volume 66 Issue 10 Pages 3030-3033
    Published: 1993
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    Free radical allylations of α-seleno carbonyl compounds with tributyl-substituted 2,4-pentadienyltin, 2-methyl-2-propenyltin, 2-butenyltin, and 3-methyl-2-butenyltin, are described. Such successful C–C bond formations, in particular with the 2-butenyltin and the 3-methyl-2-butenyltin, are owing to the high reactivity of the α-carbon radical, generated from α-seleno carbonyl compounds, toward allylic tin compounds.
  • Tetsutaro Hattori, Takatsugu Suzuki, Noriyuki Hayashizaka, Nobuyuki Ko ...
    1993 Volume 66 Issue 10 Pages 3034-3040
    Published: 1993
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    Nucleophilic aromatic substitution (SNAr) of 2-methoxybenzoic esters derived from 2,6-dialkylphenols by aryl Grignard reagents affords 1,1′-biphenyl-2-carboxylates in excellent yields by proper choice of the bulk of the 2,6-dialkyl-substituents. The phenoxyl protecting groups can be easily removed from the resulting biphenyl-2-carboxylates to the free acids by treatment with potassium hydroxide in aqueous ethanol (2,4,6-trimethylphenyl and 2,6-diisopropylphenyl esters) or sodium methoxide in toluene–hexamethylphosphoric triamide (2,6-di-t-butyl-4-methylphenyl esters). The regioselective biphenyl coupling reaction via the SNAr process is utilized for the key-step construction of the biphenyl skeleton in a formal synthesis of cannabinol.
  • Keiko Mochizuki, Ken Ohmori, Harumi Tamura, Yoshikazu Shizuri, Shigeru ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3041-3046
    Published: 1993
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    Among the cyclodepsipeptides, beauveriolides I (1) and II (2) have been isolated from the mycelium of Beauveria sp., and their stereostructures were elucidated by spectral analyses coupled with syntheses of the corresponding 3-hydroxyoctanoic acid derivatives. Beauveriolide I (1) exhibited moderate insecticidal activities against Spodoptera litura and Callosobruchus chinensis.
  • Kensaku Morihara, Tomoko Iijima, Hiromi Usui, Toyoshi Shimada
    1993 Volume 66 Issue 10 Pages 3047-3052
    Published: 1993
    Released: August 16, 2006
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    Our molecular imprinting procedures were used for molecular footprint cavities formation on the surface of an amorphous clay mineral. The imprinting with a template, N-benzoylsulfonamide, generated footprint cavities on the surface of Japanese Active Clay (sulfuric acid-treated Japanese Acid Clay). The cavities showed specific catalysis toward transacylation of benzoic anhydride that served as a corresponding substrate. This finding provided an experimental clue to study the adsorption mechanism of the Active Clay surface that has hardly been defined so far. Additionally, our comments on the significance of footprint imprinting in chemical evolution are described briefly.
  • Takashi Matsumoto, Yasutaka Tanaka, Hiromitsu Terao, Yoshio Takeda, Ma ...
    1993 Volume 66 Issue 10 Pages 3053-3057
    Published: 1993
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    Salvinolone, saprorthoquinone, and 4-hydroxysapriparaquinone isolated from the roots of Salvia prionitis Hance. were synthesized starting from (+)-dehydroabietic acid via 11,12-dimethoxyabieta-8,11,13-trien-7-one and 12-methoxyabieta-8, 11,13-triene.
  • Masanori Kosugi, Takashi Sakaya, Shinji Ogawa, Toshihiko Migita
    1993 Volume 66 Issue 10 Pages 3058-3061
    Published: 1993
    Released: August 16, 2006
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    Allyl bromide adds to a terminal acetylene under the palladium complex to give 1-bromo-1,4-pentadiene which can further react with organotin compounds without further addition of palladium complex to give 1-substituted 1,4-pentadiene. These two reactions involving different catalytic species can be composed into the consecutive one-pot process.
  • Hitoshi Tamiaki, Kimiatsu Nomura, Kazuhiro Maruyama
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3062-3068
    Published: 1993
    Released: August 16, 2006
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    β-Turned peptide-bridged diporphyrinyl compounds were prepared. Each isomeric monozinc complexes were easily available; metal-free porphyrin–peptide–zinc porphyrin and zinc porphyrin–peptide–metal-free porphyrin. In the isomers, the intramolecular energy transfer efficiencies from zinc porphyrin moiety to metal-free porphyrin moiety were the same from analysis of the steady-state fluorescence spectra, indicating that the efficiencies should be independent upon the linked peptide spacer and dependent upon the distance between the porphyrin moieties in the molecule. Singlet energy might migrate intramolecularly from zinc porphyrin moiety to metal-free one mainly by through-space mechanism.
  • Hiroshi Sato, Takanobu Noguchi, Seimei Yasui
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3069-3078
    Published: 1993
    Released: August 16, 2006
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    A new selective catalyst was developed for the dimerization of propylene to 2,3-dimethylbutenes (DMBS). It comprises five components: nickel naphthenate (Ni(naph)2)/AlEt3/PR3/diene/chlorinated phenol. Among them, chlorinated phenol is an essential component for activating the catalyst. Both the dimerization of propylene and the isomerization of the produced 2,3-dimethyl-1-butene (DMB-1) to 2,3-dimethyl-2-butene (DMB-2) are accelerated in proportion to the content of the chlorinated phenol as well as to the number of chlorine atoms on the chlorinated phenol. These effects are attributed to the Lewis acidity of the reaction product between AlEt3 and the chlorinated phenol. Thus, either DMB-1 or DMB-2 can be produced selectively by controlling the composition of the catalyst.
    The content of DMBS mainly depends upon the phosphine ligand; this ligand effect is discussed in terms of the 31P NMR chemical shift. A high content of DMBS of up to 85% in propylene dimers was attained when phosphines with chemical shifts between 0 and −30 ppm were used.
  • Hiroshi Sato, Hideto Tojima
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3079-3084
    Published: 1993
    Released: August 16, 2006
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    A small amount of water was found to increase the activity of catalyst (A) for the selective dimerization of propylene to 2,3-dimethylbutenes (DMBS),

         Ni(naph)2/AlEt3/PR3/Diene/Chlorinated phenol,       (A)

    where Ni(naph)2 denotes nickel naphthenate. The activity increased by about three to five times upon the addition of H2O in amounts of 0.2 to 0.8 mole per mole of AlEt3; the maximum activity was obtained at around 0.5 molar ratio of H2O to AlEt3. On the other hand, the reaction product between H2O and AlEt3 in a molar ratio of 0.5 was isolated and was identified to be μ-oxo-bis(diethylaluminum), the accelerating effect of which was also proved to be high. It is, therefore, concluded that the Lewis acidity of μ-oxo-bis(diethylaluminum) activates the Ni–H bond of the active species through coordination to the square-planer complex of nickel.
  • Junko Kondo, Nan Ding, Ken-ichi Maruya, Kazunari Domen, Toshiharu Yoko ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3085-3090
    Published: 1993
    Released: August 16, 2006
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    The selective hydrogenation of benzoic acid to benzaldehyde on ZrO2 and Cr2O3–ZrO2 at 523 K was studied by IR spectroscopy. An enhancement of the hydrogenation rate of benzoic acid by Cr2O3 doping to ZrO2 was observed. The main role of Cr2O3 was considered to be the step of activating hydrogen. An intermediate species was observed based on the IR bands during a transformation from the adsorbed benzaldehyde to the benzoate at lower temperatures. This is discussed in conjunction with the reaction mechanism of the hydrogenation. The intermediate species was regarded as being the chemisorbed benzaldehyde by an analysis of the observed IR bands.
  • Tetsuo Saji, Ken-ichi Ebata
    1993 Volume 66 Issue 10 Pages 3091-3093
    Published: 1993
    Released: August 16, 2006
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    Polystyrene latex thin films were prepared on an indium tin oxide electrode by controlled-potential electrolysis of an aqueous solution containing a nonionic surfactant with a ferrocenyl moiety and dispersed latex particles. Thermal treatment rendered the film more transparent, and made the ITO electrode covered with the film inert against electrochemical reaction of hexacyanoferrate(II) due to the disappearance of the intergranular space in the film.
  • Shin-ichiro Fujita, Hiroto Ito, Nobutsune Takezawa
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 10 Pages 3094-3096
    Published: 1993
    Released: August 16, 2006
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    Methanol Synthesis from CO2–H2 was carried out over a ZnO catalyst. Pretreatments with a CO–H2 mixture caused a transient increase of the methanol formation as Bowker et al. found. It was shown that methoxide species was formed in the course of the pretreatments, being readily hydrolyzed to methanol by water formed via the reverse water gas shift reaction.
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