Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 67 , Issue 8
Showing 1-50 articles out of 64 articles from the selected issue
  • T. Settu, R. Gobinathan
    1994 Volume 67 Issue 8 Pages 1999-2005
    Published: 1994
    Released: July 28, 2006
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    Precursor powders of pure and 10 mol% ceria doped zirconia have been prepared by physical gelation of zirconium(IV) dichloride oxide, cerium nitrate, and oxalic acid using triple distilled water as solvent at room temperature (ca. 27 °C). Both the zirconium(IV) and doped zirconium(IV) oxalate oxide gels are transparent and are dried at 40 °C. The thermal evolution and crystallization behaviors of the amorphous gels have been investigated by TGA, DTA, and X-ray diffraction analysis. On calcination at 850 °C, zirconia precursor transformed to a monoclinic phase whereas only tetragonal phase has been observed for doped zirconia precursor. Estimation of the surface area and IR characterization have also been carried out for the prepared dried powders.
  • Maher M. A. Hamed, Mona B. Mohamed, Mohamed R. Mahmoud
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2006-2010
    Published: 1994
    Released: July 28, 2006
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    Charge-transfer complexes of cyclic thioethers with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone; tetracyanoethylene; chloranil as π-acceptors and with iodine as a σ-acceptor, have been investigated. The spectral characteristics and stability of the formed CT complexes were examined, and are discussed in terms of the donor molecular structure, the nature of the electron acceptor and the solvent polarity. It is deduced that the formed CT complexes are mainly of the weak n–π or n–σ type, where the ground-state wave function is described primarily in terms of the nonbonding structure (D–A). The ionization potentials of the donors were calculated based on the CT energies of their CT complexes. Moreover, solid 1 : 1 CT complexes were synthesized and characterized.
  • Masahiro Hiramoto, Yoshitaka Sakaue, Masaaki Yokoyama
    1994 Volume 67 Issue 8 Pages 2011-2016
    Published: 1994
    Released: July 28, 2006
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    Extrinsic carrier photogeneration in perylene pigment was studied by means of the electric field-induced fluorescence quenching. Perylene pigment mixed with small amount of phthalocyanine exhibited the effective enhancement of carrier generation efficiency together with decreasing field-induced fluorescence quenching, contrary to the expectation that both should be enlarged owing to the competitive relation between carrier generation and carrier recombination entailing fluorescence. The model assuming the existence of another efficient channel to photogenerate geminate ion pairs through perylene/phthalocyanine molecular contacts, solved this intriguing result reasonably.
  • Sadamu Yoshida, Kozo Kozawa, Naoki Sato, Tokiko Uchida
    1994 Volume 67 Issue 8 Pages 2017-2023
    Published: 1994
    Released: July 28, 2006
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    The energy structures and photoelectric behavior of sandwich-type organic photocells, configurations of which are Au/benzo[b]phenothiazine/Al, Al/dibenzo[a,h]phenothiazine/In, Al/dibenzo[a,j]phenothiazine/In, and Au/triphenodithiazine/Al, are investigated. The electrical and photovoltaic measurements show that the blocking contacts are formed at the pigments/Al interfaces in these four cells. These experimental results are consistent with the proposed energy band structures of the cells, which are estimated on the basis of the experimental results of ultraviolet photoelectron spectra and the threshold values in photocurrent action spectra.
  • Naoyuki Urasaki, Sadamu Yoshida, Takashi Ogawa, Kozo Kozawa, Tokiko Uc ...
    1994 Volume 67 Issue 8 Pages 2024-2030
    Published: 1994
    Released: July 28, 2006
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    The homogeneous electrochemical oxidations of four phenothiazine derivatives, three isomers of benzophenothiazine and triphenodithiazine, were studied in acetonitrile solution together with phenothiazine itself. Their first and second redox potentials were determined by means of cyclic voltammetry. In all the materials examined, reversible one-electron oxidations were characterized. The electrogenerated cation radicals, except for triphenodithiazine, underwent a second one-electron oxidation and, after a subsequent chemical transformation, formed the corresponding benzophenothiazinium cations. For triphenodithiazine, only the first oxidation potential was observable under our experimental conditions. The electronic states of both the intermediates and the final products of electrolytic oxidation were identified by their electronic absorption spectra and electron spin resonance absorption spectra. The values of the first oxidation potential of the benzophenothiazines were proportional to the ionization energies, which were given by molecular orbital calculations.
  • Hiroyuki Noda, Kazuo Oikawa, Hiroaki Ohya-Nishiguchi, Hitoshi Kamada
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2031-2037
    Published: 1994
    Released: July 28, 2006
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    ESR spin trapping technique has been applied to determine the quantum efficiency of the hydroxyl radical production from semiconductors such as anatase and rutile TiO2, WO3, and ZnO photoexcited with a 365 nm UV lamp in water and aqueous H2O2 solution. The quantum efficiency for anatase TiO2, rutile TiO2, and WO3 in H2O2 solution was 3—4 times larger than that in water. Its maximum values, 4.6% in water and 14.8% in 1 mmol dm−3 H2O2 solution were obtained from anatase TiO2. The reaction of the hydroxyl radical from photoexcited semiconductors with ethanol has been investigated in relation to the C-centered radical production in aqueous ethanol solution. The possible photocatalytic redox mechanisms are discussed concerning the reactions caused by photoinduced electron-hole pairs and produced radicals.
  • Junko Takahashi, Tadamasa Shida
    1994 Volume 67 Issue 8 Pages 2038-2046
    Published: 1994
    Released: July 28, 2006
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    The effect of vibronic coupling on the absorption band at ca. 400 nm as well as on the Raman spectrum of the phenoxy radical (The IUPAC nomenclature recommends phenoxyl. However, in spectroscopic studies most authors prefer phenoxy to phenoxyl.) is examined by ab initio MO calculations within the framework of the adiabatic approximation. The vibronic coupling effect is represented in terms of the linear non-Condon term in the analysis of the absorption band and in terms of the B-term in the Raman study. The inclusion of the coupling effect improves theoretical spectra fits to experimental spectra.
  • Tomoyuki Itaya, Yoshiya Kawabata, Hiroshi Ochiai, Kazuyoshi Ueda, Akir ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2047-2052
    Published: 1994
    Released: July 28, 2006
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    The CT complexation between 9,10-dimethoxyanthracene-2-sulfonate ion (DMACS; donor) and 9,10-anthraquinone-2-sulfonate ion (AQS; acceptor) has been studied in aqueous solution of poly(1,1-dimethyl-3,5-dimethylenepiperidinium chloride) (PDDP+Cl). In aqueous PDDP+Cl solution, both DMACS and AQS are electrostatically bound to the polyion and the CT complex between them is formed around the polyion due to the close proximity of DMACS–AQS pairs. By comparing the CT complexation in aqueous PDDP+Cl solution with that in aqueous poly(allylammonium chloride) (PAAH+Cl) solution studied previously, the effects of the charge density of the polyion, the structure of charged groups on the polyion and the local conformation of the polyion upon the CT complexation have been clarified. A plausible structure of the CT complex has been determined so as to satisfy the symmetry-allowed interaction between the HOMO of DMACS and the LUMO of AQS. The CT complex interacts more strongly with the polyion than Cl and the decrease in the viscosity of the polymer (the contraction of the polymer chain) is more effectively caused by the CT complexation. Moreover, the strength of the association (stacking interaction) of aromatic counterions (DMACS, AQS) including the CT complexation affects the binding of these counterions to the polyion.
  • Seiji Yamasaki, Hisao Tsutsumi
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2053-2056
    Published: 1994
    Released: July 28, 2006
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    In chiral oil gelators, only 1,3 : 2,4-di-O-benzylidene-D-sorbitol (D-DBS) can form gels with alcoholic solvents. The D-DBS concentration dependence of the state in the binary system D-DBS/ethylene glycol, were studied using optical, rheological and spectral measurements. Based on the changes in the transmission and mechanical properties, two phase transition points, which depended upon the D-DBS concentration, were observed at 10 and 30 mM. The low-concentration point was the critical gel concentration. The gel was formed above 10 mM. D-DBS formed spherical domains in the gel between 10—30 mM and made continuous crystals on the entire gel above 30 mM. The aggregated structure of D-DBS in ethylene glycol was studied, utilizing electronic and circular dichroism measurements. According to the gelation, the absorption of the transition moment along the long axis of the benzene ring was red-shifted. The relative orientation changed in 10—30 mM from the hyperchromism and hypochromism of the electronic absorptions, but was fixed above 30 mM. D-DBS exhibited remarkable CD enhancements due to the formation of a gel. The concentration dependence of the molar ellipticities of the CD absorptions was similar to the tendency of the electronic spectra. This indicated that the aggregated structure was changed, depending upon the D-DBS concentration in ethylene glycol; the optical and mechanical properties were related to the aggregated structure which D-DBS formed.
  • Yoshikiyo Moroi, Keisuke Matsuoka
    1994 Volume 67 Issue 8 Pages 2057-2061
    Published: 1994
    Released: July 28, 2006
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    Electric conductivities at 298.2 K of sodium dodecyl sulfate solution above the cmc were analyzed from the concentrations of counterion, surfactant ion, and micelle based upon the mass action model of monodisperse micelle formation, where the three micellization parameters (log Kn = 230, n = 64, and m = 46.7) were employed. The ionic conductivity of micelle was found to be inconsistent not only with the micellar size of the identical charge but also with the conductivity of the dynamic radius of micelle of the identical charge. The inconsistencies could be solved by the hopping reaction of counterions between micelles through the overlapping of ionic diffuse double layers around micelle that takes place when two micelles come close together. The hopping reaction was found to start when the distance between micelles becomes less than 5 times the Debye length.
  • Kokichi Hanaoka, Ryotaro Kiyono, Masayasu Tasaka
    1994 Volume 67 Issue 8 Pages 2062-2068
    Published: 1994
    Released: July 28, 2006
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    The thermal membrane potential cell with solution inlet channels was constructed from two blocks of poly(methyl methacrylate). Using the cell the thermal membrane potentials across anion-exchange membranes Aciplex A-201, A-211, and A-221, and Neosepta AM-1 were observed in inorganic electrolytes: KF, KCl, KI, KNO3, KClO3, and KIO3, and in organic electrolytes: HCOONa, CH3COONa, CH3COOK, and C6H5COONa. The thermal membrane potential Δψ across the anion-exchange membrane was always positive at the cold solution side. The temperature coefficient of the thermal membrane potential per unit temperature difference ΔψT is proportional to the logarithmic activities of the ions and the slope of this plot was R/F in the range of ideal permselectivity for the counterions except Aciplex A-221. The transported entropies of the counterions in the membrane were estimated by combining data for the thermal membrane potential, thermoosmosis, and electroosmosis. For all types of membranes, both terms of water and ions in the thermal membrane potential increased with the increasing of the friction coefficient of ions.
  • Katsuaki Shimazu, Kyohei Kaneda, Hideaki Kita
    1994 Volume 67 Issue 8 Pages 2069-2074
    Published: 1994
    Released: July 28, 2006
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    The adsorbed species formed from methanol on platinum electrodes have been examined with an electrochemical quartz crystal microbalance (EQCM). The mass of the adsorbed species per surface platinum site was determined from the frequency response of the EQCM, together with number of electrons per Pt site required to oxidize the adsorbed species and coverage from the current response of the EQCM. These values were used to calculate the molar mass of the adsorbed species and the number of adsorption sites. The average composition of the adsorbed species was similar both in 0.1 M HClO4 and 0.01 M NaOH, and was COH2.0—2.4. The composition was independent of the adsorption time and the adsorption potential unless the coverage was below 0.2, where accurate determination of the composition was not possible. The average number of adsorption sites was 3.0 in 0.1 M HClO4 and 2.6 in 0.01M NaOH.
  • Takayuki Abe, Youichiro Miki, Kingo Itaya
    1994 Volume 67 Issue 8 Pages 2075-2078
    Published: 1994
    Released: July 28, 2006
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    The influence of an underpotentially deposited adlayer of copper on the oxygen reduction reaction (ORR) at Au(111) has been studied in a 0.05 M H2SO4 solution using hanging meniscus rotating disk voltammetry. The total inhibition of the ORR was found after the formation of the first Cu adlayer. Two possible structures for the Cu adlayer on Au(111) take into account inhibition of the ORR. The total inhibition observed in the present study can be explained by a honeycomb (√3 × √3)R30° structure, rather than a simple (√3 × √3)R30° Cu adlayer. A bridging two-site process (disproportionation reaction) is not expected to occur on the honeycomb Cu adlayer.
  • Kohsuke Fukushima, Masayuki Someya, Ryosuke Shimozawa
    1994 Volume 67 Issue 8 Pages 2079-2085
    Published: 1994
    Released: July 28, 2006
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    We measured the binding isotherms of a local anesthetic, tetracaine, to dilauroylphosphatidic acid (DLPA) and dilauroylphosphatidylcholine (DLPC) mixed vesicles along with their pure vesicles. The binding isotherms were constructed by the equilibrium dialysis method at different pH (5.5, 7.0, 8.0) at 35 °C. The binding isotherms were analyzed based on the equations combined with Langmuir and Hill-type isotherms, and the parameters characterizing the binding isotherms were evaluated. The thus-obtained binding parameters for pure vesicles well reproduce the binding isotherms for the mixed vesicles by taking account of the mixing ratios. This indicates that DLPA and DLPC also provide independent binding sites for tetracaine, as for previously reported dibucaine. The estimated values of the binding parameters for these two anesthetics, i.e., tetracaine and dibucaine, were compared in terms of the strength of the anesthetic action as well as the molecular structure.
  • Haruhiko Yokoyama, Toshiaki Hiramoto, Kazuteru Shinozaki
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2086-2092
    Published: 1994
    Released: July 28, 2006
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    Conductivities for aqueous solutions of alkali metal salts of tris(oxalato)chromate(III) ([Cr(ox)3]3−) were measured at various temperatures from 0 to 50 °C. Ion-association constants (KA) between the complex ion and alkali metal ions increased in the order Li+ << Na+ < K+ < Rb+ < Cs+ and had minimum values (KA(min)) at characteristic temperatures (tmin) in the observed temperature range except for the lithium ion. The appearance of minima of KA suggested the formation of contact ion pairs besides that of solvent-separated ones. The contact ion-pair formation was considered to be assisted by weak hydration of alkali metal ions and enhanced with decreasing their hydration strength. The lithium ion was presumed to form only solvent-separated ion pairs on the basis of extremely small ion-association constants. Temperature dependence of log KAfor each ion association could be represented by the equation: log KA = p(ttmin)2 + log KA(min). A common relationship between p and tmin was found out for the ion-association systems of [Cr(ox)3]3−, [Co(NH3)6]3+, and [Co(en)3]3+ (en = ethylenediamine), and p was expressed by an empirical quadratic equation in tmin. The standard enthalpy changes of ion association (ΔHas°) at any temperature for these complex systems could be reproduced within ±0.2 kJ mol−1 by use of these equations with the experimental tmin. Hydration behavior of [Cr(ox)3]3− was also discussed based on limiting molar conductivities and their temperature dependence.
  • Keiichi Tsukahara, Yuki Nishikawa, Chieko Kimura, Naoko Sawai, Takeshi ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2093-2097
    Published: 1994
    Released: July 28, 2006
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    Horse heart metmyoglobin was reconstituted with magnesium(II) porphyrin, [Mg(dp)] (3,7,12,17-tetramethyl-2,18-bis(2-carboxyethyl)porphyrinatomagnesium(II)). Photoinduced electron-transfer (ET) between magnesium myoglobin (MgDPMb) and cationic and anionic quenchers, such as viologens and anthraquinone-2-sulfonate (AQS), has been studied in an aqueous degassed solution. None of the quenchers examined in this work formed a detectable associated complex with MgDPMb. The thermal backward ET reaction was observed for these quenchers. Not only photoinduced ET but also thermal backward ET reactions were insensitive to the driving force of the reactions. Moreover, there was little effect of metal-ion substitution; the rate of reaction was similar to that for zinc myoglobin. Thus, the reactions are controlled by conformational changes in the myoglobins.
  • Shaban E. Ghazy, Mohamed A. Kabil
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2098-2102
    Published: 1994
    Released: July 28, 2006
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    Microgram amounts of copper(II) in one liter of water are quantitatively separated selectively as copper(II) acetate with oleic acid surfactant at pH range 6.5—7.5. The floated scum is separated, after shaking for few seconds, and measured colorimetrically at 700 nm. Beer’s law is obeyed in the concentration range (0.5—5) × 10−4 mol dm−3, {3.18—31.8 ppm of copper(II)}. Alternatively, the copper in the scum is eluted by nitric acid 0.1 mol dm−3, completed to the suitable volume required for copper atomic absorption measurement at 324.7 nm with 1 ppm detection limit. The different factors affecting the selective flotation of copper(II) have been studied. It has been found that iron(III) seriously depresses the flotation efficiency. The flotation mechanism is discussed. The method of the separation and determination is rapid and applicable to 50 ppb copper(II) concentration level in natural waters.
  • Rameshwar Dass, Jaswant Ram Mehta
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2103-2106
    Published: 1994
    Released: July 28, 2006
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    Sodium dithionite has been recommended as a new reductant in the thiocyanate method for the spectrophotometric determination of molybdenum. The study is based on prior extraction of molybdenum(VI)–thiocyanate species in ethyl acetate from 0.8 mol dm−3 HCl medium followed by reduction of the complex with dithionite in the organic extract. The orange yellow color so obtained is measured at λmax 468 nm against a reagent blank. The 1 : 5 (Mo : SCN) complex is stable for 1 h in ethyl acetate and obeys Beer’s law over the concentration range 0—2.6 ppm of molybdenum (optimum range for accurate determination is 0.7—2.5 ppm). The molar absorptivity and Sandell sensitivity of the complex are 1.79 × 104 dm3 mol−1 cm−1 and 0.0053 μg Mo cm−2, respectively. The relative standard deviation for nine replicate determinations of 2 μg Mo cm−3 is ±1.1%. Of the tested 40 cations and 24 anions including complexing agents only thiourea interferes in the procedure. The method is sensitive and highly selective. It is applicable to the determination of molybdenum in steels and flue dust samples with satisfactory results.
  • Tohru Saitoh, Manabu Okuyama, Madoka Minagawa, Tamio Kamidate, Hiroto ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2107-2110
    Published: 1994
    Released: July 28, 2006
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    We investigated the effect of halogen substitution of N-alkylcarbonyl-N-phenylhydroxylamines on the extraction of lanthanoids(III). A p-chloro substituent of a phenyl group increased the acidity of R-PHAs by 0.3—0.5 pKa units, and a bromo substituent on the α carbon of the acyl group increased it by 1.5 pKa units. In the former substitution, the separation factor for pairs of lanthanoids(III) and yttrium(III) remained unchanged, whereas in the latter the separation factor was considerably reduced. Hence, the chloro substitution at the phenyl group was a good choice for lowering pH values in the extraction of lanthanoids(III). The pH region was suitable for extracting lanthanoids(III) while preventing the formation of their hydroxo complexes.
  • Yoichi Kikuchi, Mitsuru Kubota, Toshio Suzuki, Kiyoshi Sawada
    1994 Volume 67 Issue 8 Pages 2111-2114
    Published: 1994
    Released: July 28, 2006
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    A series of poly(oxyethylene) derivatives (POE compound) complexes of alkali metal and barium ions were extracted into 1,2-dichloroethane (1,2-DCE) by forming ion-pairs with picrate ion. Water molecules were coextracted into 1,2-DCE with the ion-pairs. The mean number of water molecules bound to the POE compound, XH2O,S, and its complex, XH2O,comp, in water saturated with 1,2-DCE was determined by means of aquametry. The XH2O,S value increases with the increase in the number of the oxyethylene units (EO unit) of the POE compound. The XH2O,comp value decreases in the order Li+ > Na+ > K+ ≈ Rb+ ≈ Cs+ in any POE compound systems, and increases with the number of EO units of the POE compounds for a given metal ion. These results are interpreted by the hypothesis that the water molecules bound to the complex are those hydrated to the central metal ion, and the hydrated metal ion is surrounded by the EO chain with a helical conformation in the complex. The large number of water molecules are coordinating to the lithium ion complexes and bring about a serious distortion in the helical structure of the complexes. Because of the ion-pair formation with two picrate ions, the XH2O,comp values of barium ion complexes are smaller than those of potassium ion complexes.
  • Kouzou Yoshitani
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2115-2120
    Published: 1994
    Released: July 28, 2006
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    For the conversion from quinquedentate complexes, [Co(edtaH)(H2O)] and [Co(edta)(H2O)], into the sexidentate complex, [Co(edta)], the respective volume changes were measured from the density data at 25 °C. The volume change was determined as well for the proton dissociation of [Cr(edtaH)(H2O)]. A comparison of the volume changes in the Co(III) system with the corresponding Cr(III) system supports the recent view that edta forms a sexidentate complex with Cr(III) in the pH 3.5—6.5 range.
  • A. Ramesh, T. V. Ramakrishna, M. S. Subramanian
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2121-2124
    Published: 1994
    Released: July 28, 2006
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    A rapid and sensitive spectrophotometric method has been developed based on the extraction of the ion-association complex formed between ICl2 and Rhodamine 6G+ into benzene. The ICI2 is formed through iodine which is liberated during the oxidation of iodide by the selenium(IV) present in sulfuric acid medium. The method is sensitive and down to 0.1 μg selenium could be determined in an aqueous phase volume of 10 ml. The extracted Rhodamine 6G+–ICl2 complex has a molar absorptivity of 4.8 × 105 dm3 mol−1 cm−1 at 535 nm. Beer’s law is obeyed over the range 0.1 to 0.9 μg of selenium. The relative standard deviation is 2.4%. The method is made more sensitive and selective by adopting the aluminium hydroxide collection procedure. The interference of few ions such as Fe3+, VO3, TeO32− and Sb5+ which were collected along with selenium on aluminium hydroxide, were overcome by adding proper masking agents. The method was applied to the determination of selenium in environmental ash sample, copper ore, bark sample, and shampoo preparations.
  • Tsuyoshi Kijima, Yoshikuni Kato, Kaoru Ohe, Masato Machida, Yohichi Ma ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2125-2129
    Published: 1994
    Released: July 28, 2006
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    The uptake of two different types of cationic calix[4]areneoctols by Cu(II)–montmorillonite was studied at 25 °C. p-Aminobezylated calix[4]areneoctol 1 forms an intercalated phase in which the guest molecules are arranged as a 10.8 Å thick monolayer, with a cone-type conformation and with their cavity axes perpendicular to the inorganic layers. Thermogravimetric and copper(II) release data suggest that the calixareneoctol molecules are taken up in their divalent form and act as a prop to yield a vacant space of 42% in interlayer porosity. The molecules of dimethylammoniomethylated calix[4]areneoctol 2 are also intercalated as a monolayer, but initially in their divalent form and finally in the di- and mono-valent mixed form to fully occupy the interlayer space. The striking contrast between the two calixareneoctols as guest species is substantially due to the difference in bulkiness of their ammonio-substituted groups.
  • Takashi Kajiwara, Tadashi Yamaguchi, Hiroki Oshio, Tasuku Ito
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2130-2135
    Published: 1994
    Released: July 28, 2006
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    A new nickel(II) complex with the composition of Ni2Cl2(L)(ClO4)2·1.5H2O (L = α,α′-bis(5R(S),7S(R)5,7-dimethyl-1,4,8,11-tetraazacyclotetradecan-6-yl)-o-xylene) has been prepared via a four coordinate complex [Ni2(L)] (ClO4)4·3H2O from [Ni2(μ-Br)Br2(L)]Br·H2O. The compound crystallizes in orthorhombic space group Ccm21 with cell parameters at −80 °C, a = 21.90(1), b = 20.28(1), c = 19.63(1) Å, V = 8718(1) Å3, Z = 8. The crystal consists of the cationic dinuclear unit [Ni2(μ-Cl)Cl2(L)]+, the counter anion ClO4, and water of crystallization. In [Ni2(μ-Cl)Cl2(L)]+, three chloride ions and two nickel ions are alternately arranged in an almost linear manner, and two cyclam rings with the most stable trans-III type conformation are arranged in a face-to-face manner. This cationic dinuclear unit is further connected to each other by sharing the terminal Cl ligand to form pseudo one-dimensional chain structure of the ···Cl–Ni–Cl–Ni–Cl··· type. However, one of the Cl atoms which bridges the dinuclear units is statistically disordered at two positions along the chain and thereby the repeating unit in the chain is a chloro bridged dimer of the dinucleating ligand complex. The neighboring Ni–Cl distances range from 2.568(4) to 2.855(4) Å. The temperature dependent magnetic behavior in the range of 25—300 K has been interpreted by the usual Heisenberg–Dirac–Van Vleck model, assuming that only three Ni(II) ions in {Ni2Cl2(L)}2 are paramagnetic. The best fit parameters were J = −48.2(3) and J′ = −11.2(3) cm−1 for = −2J(S1·S1′) − 2J′(S1·S2).
  • Masaru Kimura, Ikuko Miyamoto
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2136-2138
    Published: 1994
    Released: July 28, 2006
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    The ligand-substitution reaction of the pentaamminechlorocobalt(III) ion, [Co(NH3)5Cl]2+, with ethylenediaminetetraacetate (EDTA) (which denotes all the forms of EDTA, i.e. edta4−, Hedta3−, H2edta2− etc.) occurred efficiently in the presence of the activated carbon (AC) in aqueous media of pH 4.7, where the AC acts as a catalyst of the electron-transfer mediator. The ligand-substitution reaction constitutes a chain reaction composed of an AC and AC+ cycle, where the substitution reaction is initiated by the electron-transfer from AC to the cobalt(III) complex. The formation rate of [Co(edta)] by the substitution reaction between [Co(NH3)5Cl]2+ and EDTA was of the first-order with respect to concentrations of not only [Co(NH3)5Cl]2+ but also AC, and was of the zero-order with respect to the EDTA concentration. Further, the rate was irrespective of the dissolved oxygen O2. The substitution reaction was always quantitative, i.e. [[Co(NH3)5Cl]2+]decreased = [[Co(edta)]]formed at any reaction time up to completion of reaction.
  • Hisashi Okawa, Minoru Mitsumi, Masaaki Ohba, Masahito Kodera, Naohide ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2139-2144
    Published: 1994
    Released: July 28, 2006
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    The reaction of potassium calcium tris(dithiooxalato)chromate(III) hexahydrate KCa[Cr(dto)3]·6H2O, a metal(II) salt and a tetrapropylammonium bromide (NPr4Br) in aqueous methanol forms bimetallic assemblies {NPr4[MCr(dto)3]}x (M = Fe (1), Co (2), Ni (3), Zn (4)), where the dto group bridges Cr(III) and M(II) ions through the sulfur atoms to Cr(III) and through the oxygen atoms to M(II) to provide an alternate array of Cr(III) and M(II) ions. The magnetic susceptibility data for 13 in the temperature range 5—300 K obey the Curie Weiss law (χM−1 = (Tθ)/C) with a positive Weiss constant (+18 K for 1, +24 K for 2, and +41 K for 3), and the effective magnetic moments increase with decreasing temperature. The megnetization studies (field-cooled magnetization, remnant magnetization, and zero-field cooled magnetization) reveal the ferromagnetic phase transition at TC = 8, 16, and 23 K for 1, 2, and 3, respectively. The assembly 4 shows paramagnetic behavior in the temperature range of 5—300 K.
  • Kazuo Kashiwabara, Masakazu Kita, Junnosuke Fujita, Saeko Kurachi, Shi ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2145-2150
    Published: 1994
    Released: July 28, 2006
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    The crystal structures of [CoCl3(mmtp)] (mmtp = 1,1,1-tris(dimethylphosphinomethyl)ethane) (complex 1) and [Co(CN)3(mmtp)]·2H2O (complex 2) were determined by the single-crystal X-ray diffraction method. Crystal data and final R values are; for complex 1, orthorhombic, P21nb (c, a, b setting of Pna21), a = 13.545(1), b = 13.875(1), c = 9.315(1) Å, V = 1750.7(3) Å3, Dx = 1.58, Dm = 1.57(3) g cm−3, and Z = 4, and R = 0.046 for 1999 reflections. For complex 2, orthorhombic, P21nb, a = 14.345(2), b = 15.330(2), c = 9.229(1) Å, V = 2029.4(4) Å3, Dx = 1.39, Dm = 1.35(2) g cm−3, and Z = 4, and R = 0.039 for 2715 reflections. The Co–P bond distances of av 2.203(2) Å for complex 1 and of av 2.228(1) Å for complex 2 are fairly shorter than those (av 2.331(9) Å) in [Co(mmtp)2][Co(CN)6]·2.25H2O, in which the Co–P bonds are mutually in the trans positions, indicating the strong trans influence of the phosphino group.
  • Yutaka Nakamura, Akio Ito, Chung-gi Shin
    1994 Volume 67 Issue 8 Pages 2151-2161
    Published: 1994
    Released: July 28, 2006
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    Eight kinds of peptide antibiotics, antrimycins (1), consist of four sorts of unusual α-amino acids, that is, hydroxymethylserine, (2S,3S)-2,3-diaminobutanoic acid, (S)-2,3,4,5-tetrahydro-3-pyridazinecarboxylic acid, and dehydrovaline (ΔVal) or (E)-dehydroisoleucine (ΔIle) from the N-terminus of 1. The practical syntheses of the three segments containing these four acids, and all of the protected 1 by the usual fragment condensations of the three segments were accomplished. Moreover, after mild deprotection of the protecting groups, the two kinds of 1, antrimycins Av and Dv comprising Ala5ΔVal6 and Leu5ΔVal6 segments respectively, were synthesized.
  • Fouad M. Soliman, El-Sayed M. Yakout, Medhat M. Said
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2162-2166
    Published: 1994
    Released: July 28, 2006
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    The behavior of the reactive phosphacumulenes 2a,b, towards different α-diketone monohydrazones 1, 5, 11, and 13, acenaphthenequinone monohydrazone 8 and indantrione monohydrazone 16 has been studied. In some cases the resulted phosphoranes directly cyclize by an intramolecular Wittig reaction with the formation of pyridazinones 4a, 6, 9, 12, and 17 and pyridazinethione 4b. Structure of the new products were assigned according to consistent analytical and spectroscopic data.
  • Yasuo Yamamoto, Shosuke Sofuku
    1994 Volume 67 Issue 8 Pages 2167-2175
    Published: 1994
    Released: July 28, 2006
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    Three types of Arg–Gly–Asp–Ser–Pro–Ala–Ser–Ser (RGDSPASS)-containing cystine peptides, FR-1, FR-2, and FR-3, were designed and synthesized. These cyclic peptides exhibited high activities as a platelet aggregation inhibitor. Using rabbit platelet-rich plasma, the IC50 values of FR-1, FR-2, and FR-3 were found to be 67, 280, and 135 μM, respectively. In each peptide, the position of the Pro residue was either i + 1 or i + 2 in the turn, as observed by NMR (ROESY, NOESY, and H–D exchange of amide proton).
  • Yasuo Tohda, Tohru Kawahara, Miyuki Eiraku, Keita Tani, Nagatoshi Nisi ...
    1994 Volume 67 Issue 8 Pages 2176-2186
    Published: 1994
    Released: July 28, 2006
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    A one-pot synthesis of 2-substituted 3-nitropyridines was developed by a ring transformation of 6- or 4-substituted 1-methyl-3,5-dinitro-2-pyridones (2 or 3) with ammonia and enamines derived from ketones. Some intermediates having a 2,6-diazabicyclo[3.3.1]nonane skeleton were isolated from reactions of 3. The ring transformation proceeds via an addition-addition-elimination-elimination mechanism. Few competitive isomeric by-products, 4-substituted 3-nitropyridines and 4-nitroanilines, were formed. All the 2 substrates showed good reactivity, but the 3 substrates having electron-withdrawing substituents were less reactive and selective. 1,4,6-Trimethyl-3,5-dinitro-2-pyridone did not gave any products. The selectivity is interpreted in terms of differences of thermodynamic (main selection rule B) and kinetic stability (minor selection rule A) between the possible bicyclic intermediates which are expected to be formed via the mechanism.
  • Tyo Sone, Kazuaki Sato, Yasuhiro Umetsu, Akihiro Yoshino, Kensuke Taka ...
    1994 Volume 67 Issue 8 Pages 2187-2194
    Published: 1994
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    Unsymmetrically substituted 2,4-diaryl- and 2,3-diarylthiophenes were synthesized from 2,5-dichlorothiophene via 4-aryl-2-chlorothiophenes in two and four steps including Ni-mediated cross-coupling, respectively. Aluminum chloride-catalyzed reaction of 3-aryl-2-chlorothiophenes with some aromatic ethers unexpectedly led to the formation of the corresponding 2,4-isomers.
  • Kiyotaka Yorozu, Toshihiro Takai, Tohru Yamada, Teruaki Mukaiyama
    1994 Volume 67 Issue 8 Pages 2195-2202
    Published: 1994
    Released: July 28, 2006
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    An efficient synthesis of acid-sensitive epoxides, such as chromene oxide or epoxide of γ,δ-unsaturated alcohol, was successfully achieved by the oxygenation of corresponding olefins with the combined use of an atmospheric pressure of molecular oxygen and aldoacetal catalyzed by a cobalt(II) complex coordinated with the 1,3-diketone ligand. The reactions proceeded under mild and neutral conditions, and the desired epoxides were obtained in good yields. Neither overoxidation nor decomposition of the formed epoxide was observed under the present reaction conditions. Furthermore, various silyl enol ethers and silyl ketene acetals, acid-sensitive compounds, were also smoothly monooxygenated into the corresponding α-hydroxy ketones and α-hydroxy carboxylic acid esters, respectively.
  • Masaru Kimura, Hideki Okamoto, Setsuo Kashino
    1994 Volume 67 Issue 8 Pages 2203-2212
    Published: 1994
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    In the thermal [4+4]cycloreversions of 9-anthracenecarboxylic acid-benzene 3a, methyl 9-anthracenecarboxylate-benzene 3b, dimethyl (or diethyl) 9,10-anthracenedicarboxylate-benzene 3c (or 3d) and anthracene-1,4-difluoro(or dichloro)benzene 3f (or 3g) biplanemers, chemiluminescene was observed for 3ad only in the solid state at > 120 °C but not in a liquid phase, while 3f and 3g were not chemiluminescent. Efficient chemiluminescence was observed in the photocycloreversion of all biplanemers tested in both phases. The thermodynamic parameters for the thermal cycloreversion of these biplanemers were collected. Higher activation energies were obtained in the solid state than in the liquid phase. The higher energies favor touch of the S0 surface with the S1 surface at the transition state for effecting the chemiluminescent cycloreversion.
  • Hiroki Fukui, Toshinori Sato, Junzo Sunamoto
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2213-2218
    Published: 1994
    Released: July 28, 2006
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    The influence of fatty acids, α-linolenic acid (ALA), and linoleic acid (LA), on lipid membrane dynamics and cell proliferation was investigated. Electron-spin resonance measurements with 2-hexyl-2-(10-methoxycarbonyldecyl)-4,4-dimethyl-3-oxazolidinyloxyl revealed that the penetration of ALA or LA into the liposomal membrane causes an increase in the membrane fluidity and a decrease in the phase-transition temperature of the lipid membrane. When human colon cancer cells (RPMI4788 and BM314) and normal mouse fibroblast (L-cell) were incubated with ALA, the membrane fluidity of the cancer cells significantly increased over that of normal cells. ALA made the cancer cell membrane more fluid than did LA. When ALA was administered at a concentration of 40 μg ml−1, it showed a strong cytotoxicity against the cancer cells, but not to the normal cells. On the other hand, LA (up to 80 μg ml−1) rather promoted growth of the cancer cells. These results seem able to be interpreted as an aspect of the selective cytotoxicities of ALA.
  • Masataka Yokoyama, Yasuhiro Menjo, Makoto Ubukata, Masakazu Irie, Mika ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2219-2226
    Published: 1994
    Released: July 28, 2006
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    Transformation of alkyl N-(vinyloxy)benzimidates to alkyloxazoles proceeds through the intermediates: a charge-separated 1,2-oxazetidine derivative and then 1-hydroxy-2-[[methylthio(phenyl)methylene]imino]maleic acid diester, while their photochemical transformation takes place via a concerted [1,3] sigmatropic shift. As the extension of this reaction, the preparation of the precursor proposed for virginiamycin M2 synthesis and the reaction of N-analogs of alkyl N-(vinyloxy)benzimidates are described.
  • Shin-ichi Fukuzawa, Teruhisa Tsuchimoto, Takeshi Kanai
    1994 Volume 67 Issue 8 Pages 2227-2232
    Published: 1994
    Released: July 28, 2006
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    The cross-aldol reaction between a ketone and an aldehyde proceeded smoothly with threo diastereoselection favorably mediated by ytterbium trifluoromethanesulfonate and tertiary amine in diethyl ether or in dichloromethane. A ytterbium enolate was trapped with chlorotrimethylsilane to afford a silyl enol ether.
  • Mizue Fujio, Toshihiro Susuki, Mutsuo Goto, Yutaka Tsuji, Ken-ichi Yat ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2233-2243
    Published: 1994
    Released: July 28, 2006
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    Solvolysis rates of benzyl p-toluenesulfonate were determined in a wide variety of solvents. The solvent effects were analyzed based on the Winstein–Grunwald equation. The solvent effect on benzyl solvolysis failed to give a single linear correlation with the 2-adamantyl YOTs parameter. The lower response to the solvent polarity and the pattern of dispersion for each binary solvent series can be qualitatively interpreted in terms of nucleophilic solvent assistance. The Winstein–Grunwald analysis gave m = 0.67 and l = 0.36, but with less satisfactory precision. The use of the polarity scale Yneo derived from 2-methyl-2-phenylpropyl solvolysis in place of YOTs gave an improved correlation. A solvent polarity scale Yneo is better applicable to benzyl solvolysis than 2-adamantyl-based YOTs, since the former is compatible with the entire π-delocalization of cationic charge between aryl ring and the reaction center in the transition state.
  • Yasushi Kawai, Shin-ichi Kondo, Munekazu Tsujimoto, Kaoru Nakamura, At ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2244-2247
    Published: 1994
    Released: July 28, 2006
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    The diastereoselectivity in a bakers’ yeast reduction of various alkyl 2-alkyl-3-oxoalkanoates can be controlled by a thermal treatment of the yeast in the presence of methyl vinyl ketone. Pretreated bakers’ yeast gives the corresponding (2R,3S)-hydroxy esters selectively. Two β-keto ester reductases, named L-enzyme-1 and L-enzyme-2, are actual reductants of intact bakers’ yeast reduction. The thermal stability and inhibition constants of the purified enzymes can dictate the stereochemical outcome of pretreated bakers’ yeast reductions.
  • Tohru Yamada, Kiyomi Imagawa, Takushi Nagata, Teruaki Mukaiyama
    1994 Volume 67 Issue 8 Pages 2248-2256
    Published: 1994
    Released: July 28, 2006
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    Enantioselective epoxidation of unfunctionalized olefins is achieved by the combined use of molecular oxygen and pivalaldehyde in the presence of a catalytic amount of optically active Mn(III)–salen complexes. N-Alkylimidazoles are effective axial ligands to produce optically active epoxides with high enantioselectivities in the present procedure; that is, 1,2-dihydronaphthalene derivatives and 2,2-dialkyl-2H-chromene derivatives are converted into the corresponding optically active epoxides with 60—92% enantiomeric excess. The key intermediates in the present aerobic epoxidation are also discussed.
  • Toshio Itahara, Takashi Yoshitake, Sunao Koga, Akihiro Nishino
    1994 Volume 67 Issue 8 Pages 2257-2264
    Published: 1994
    Released: July 28, 2006
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    The treatment of nucleic acid bases, nucleosides, and nucleotides with peroxodisulfate ion in a phosphate buffer solution at pH 7.0 or water at 70—75 °C was investigated. The reaction of thymine and 5-methylcytosine nucleosides and nucleotides resulted in the oxidation of the 5-methyl groups. The oxidation products from 1,3-dimethyluracils and the time-course of the reaction of uracils led to two plausible reaction mechanisms for the oxidation of uracils.
  • Yoshiro Masuyama, Tatsuya Sakai, Takeshi Kato, Yasuhiko Kurusu
    1994 Volume 67 Issue 8 Pages 2265-2272
    Published: 1994
    Released: July 28, 2006
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    PdCl2(PhCN)2–SnCl2, bis(1,5-cyclooctadiene)nickel(0) [Ni(cod)2]/PPh3–Zn, NiBr2(PPh3)2–Zn, or Pd(OAc)2/PPh3–Zn catalytic systems induced aldol-type condensation of isopropenyl acetate with aldehydes to produce 4-substituted (E)-3-buten-2-ones. PdCl2(PhCN)2–SnCl2 was utilized in the aldol-type reaction with any arenecarbaldehyde, bearing either an electron-donating group or an electron-withdrawing group, at 50 °C in acetonitrile. Catalytic systems using zinc, in particular Ni(cod)2/PPh3–Zn, exhibited some high chemoselectivities at 60 °C in dioxane: (1) an aldehyde only reacted in the presence of an internal ester or ketone, (2) olefinic aldehydes only reacted in the presence of saturated aliphatic aldehydes, (3) reactivity in the condensation with substituted benzaldehydes is the inverse of that in usual nucleophilic addition to carbonyl compound, and (4) 2-methoxybenzaldehyde only reacted in the presence of 4-methoxybenzaldehyde. Using PdCl2(PhCN)2–SnCl2, Ni(cod)2/PPh3–Zn, or Pd(OAc)2/PPh3–Zn, cyclic enol ester, namely 5-methyl-2(3H)-furanone also caused aldol-type reaction with carbonyl compounds. The reaction with Ni(cod)2/PPh3–Zn or Pd(OAc)2/PPh3–Zn at 60 °C in dioxane selectively produced 5-substituted 4-acetyl-2(5H)-furanones via dehydrogenation of γ-substituted β-acetyl-γ-butyrolactones.
  • Yasufumi Ueda, Masatomi Kanai, Kenji Uneyama
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2273-2277
    Published: 1994
    Released: July 28, 2006
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    Perfluoroalkyl-telluration of alkynes has been performed by a (PhTe)2–NaBH4–RfX system at a low temperature (−40, −80, or −100 °C) to give 2-(perfluoroalkyl)vinyl tellurides. Meanwhile, perfluoroalkyl-sulfenylation and perfluoroalkyl-selenation were less effective. The perfluoroalkyl-telluration proceeds mainly via both SRN1 process and photochemical addition of the in situ formed perfluoroalkyl phenyl telluride (RfTePh). The efficiency of the chalcogenolate anions for perfluoroalkyl-chalcogenation was found to be the order of PhS < PhSe < PhTe.
  • Nobutsugu Yamagata, Ken Usami, Susumu Okazaki
    1994 Volume 67 Issue 8 Pages 2278-2285
    Published: 1994
    Released: July 28, 2006
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    Coral sands calcined at high temperatures of 800 and 1000 °C were found to be an effective catalyst for the oxidative coupling of methane to C2 hydrocarbons, especially with high selectivity. The coral-sand catalyst was almost composed of calcium oxide; however, it also contained small amounts of Na, Sr, Mg ions etc., and had a characteristic structure with many small pores of 2—8 μm in diameter, which were formed during calcination. In order to investigate the role of their components in C2 formation, nine kinds of catalysts were prepared from other natural calcium carbonates, such as turbo shell, short-necked clam shells, and marbles; their catalytic properties were compared with that of the coral-sand catalyst. Consequently, it seemed that the C2 yield was related to the bulk and surface concentrations of sodium in the catalyst, while the maximum-C2 selectivity at 700—800 °C was related to those of strontium. The catalysts of corals and coral sands showed the highest maximum-C2 selectivity as well as the highest strontium-content (about 1.2wt%). It was considered that the strontium ions are well-dispersed in the catalyst and that they enhance the basicity in combination with sodium ions (main active species), leading to the high C2 selectivity.
  • Fathla M. El-Cheikh, Fawzi H. Assaf, Mahmoud Khodari, Mahmoud A. Ghand ...
    1994 Volume 67 Issue 8 Pages 2286-2296
    Published: 1994
    Released: July 28, 2006
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    Studies were performed to determine the effect of 2-picoline, 3-picoline, 4-pyridinol, and 2-pyridinamine on the dissolution of untreated, anodized, and sealed aluminum and aluminum–manganese alloys at 30.0 and 40.0 °C. Conductance measurements were applied to evaluate the corrosion rate. A comparison was carried out between this newly suggested conductance method and other methods previously used to estimate the dissolution rate. This comparison shows of the reliability of this conductance method. A good correlation was observed between the basicity, structure, and the inhibition effect of all compounds investigated. The order of inhibition efficiency is increasing as: 2–pyridinamine > 4–pyridinol > 3–picoline > 2–picoline. This order described above is consistent with the evidence that the oxidized specimens show higher inhibition in the presence of additives than sealed and untreated ones.
  • Shinji Tsunoi, Noritaka Miyoshi, Akiya Ogawa, Nobuaki Kambe, Noboru So ...
    1994 Volume 67 Issue 8 Pages 2297-2300
    Published: 1994
    Released: July 28, 2006
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    Efficient separation of carbon monoxide from a binary mixture of carbon monoxide and hydrogen with selenium and secondary amines has been developed. The process consists of (i) selective reaction of CO with selenium and a secondary amine to form the corresponding ammonium carbamoselenoate 1 and (ii) thermolysis of 1 to form pure CO (99.9%) quantitatively. A Se–alcohol system is also usable but the results are inferior to that with a Se–amine system.
  • Keisuke Miyakubo, Sadamu Takeda, Nobuo Nakamura
    1994 Volume 67 Issue 8 Pages 2301-2303
    Published: 1994
    Released: July 28, 2006
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    Crystal structure of potassium hydrogen terephthalate was determined by X-ray diffraction. Crystals have monoclinic unit cells with C2/c, a = 18.776(6), b = 3.761(3), c = 11.150(4) Å, β = 94.72(3)°, V = 784.6(6) Å3, and Z = 4. Acid anions form a one-dimensional chain linked by short (RO···O = 2.459(3) Å) and symmetric hydrogen bonds. The acidic hydrogen was distributed at two equivalent sites in the hydrogen bond.
  • Bunji Uno, Toshio Kawakita, Kenji Kano, Noriko Okumura, Masashi Goto, ...
    1994 Volume 67 Issue 8 Pages 2304-2307
    Published: 1994
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    Thermodynamic constants for acid dissociation of the 2-, 3-, and 4-phenoxypyridinium, and 2-(2,6-xylyloxy)pyridinium cations were estimated by the spectroscopic method, and are extensively discussed in relation to the conformations around the bridging oxygen atom and the electronic states.
  • Hiroshi Kawano, Masayoshi Maehara, Yoshinori Nibu, Hiroko Shimada, Ryo ...
    1994 Volume 67 Issue 8 Pages 2308-2310
    Published: 1994
    Released: July 28, 2006
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    The pressure-induced frequency shift of the intramolecular vibrations in crystal was calculated using an atom–atom type intermolecular potential. The calculation indicates that the contribution of the first-order differential of the potential to the frequency shift is very small when the potential is well approximated.
  • Masaaki Oya, Hiroumi Shiina, Kentaro Tsuchiya, Hiroyuki Matsui
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 8 Pages 2311-2313
    Published: 1994
    Released: July 28, 2006
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    Thermal decomposition of COS was investigated by shock tubes between 1140—3230 K. The decay of COS and S was monitored by IR emissions and atomic resonance absorption spectrometry (ARAS) coupled with laser flash photolysis technique, respectively. The rate constants for the reactions COS + M → CO + S + M (1) and COS + S → CO + S2 (2) were determined as k1 = (4.07 ± 1.83) × 10−10exp (−257 ± 24kJ/RT), T: 1900—3230 K and k2 = (3.91 ± 1.18) × 10−11exp (−28.3 ± 0.9 kJ/RT) cm3 molecule−1 s−1, T: 1140—1680 K.
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