Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 67 , Issue 6
Showing 1-44 articles out of 44 articles from the selected issue
  • Arunabha Datta, Ravindra Y. Kelkar, Parviz Boroojerdian, Sulabha K. Ku ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1517-1521
    Published: 1994
    Released: July 19, 2006
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    The thermal stability of C60 in pure oxygen has been investigated by in-situ FT-IR and thermogravimetric analysis (TGA). It is shown that at temperatures of about 250 °C, the C60 loses its spherically symmetric structure and is oxidized to an anhydride type species. The anhydride on exposure to air is converted to an acid which however reverts to the anhydride on heating in a nitrogen or oxygen atmosphere. On heating beyond 250 °C, the C60 is completely oxidized probably to CO and CO2, but this complete oxidation appears to take place in two stages with the anhydride part of the molecule getting oxidized first. It is postulated that the lower oxidative stability of C60 compared to graphite is probably due to the greater reactivity towards oxygen of the pentagon–hexagon junction, compared to the hexagon–hexagon junction, present in C60.
  • Akiko Okumura, Mie Kitani, Michiyo Murata
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1522-1530
    Published: 1994
    Released: July 19, 2006
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    The oxygen exchange reaction between chromate ions and water is catalyzed by the addition of a small amount of periodate ions. The catalytic reaction has been studied by using 18O tracer work (0 °C, pH = 8—12, [Cr(VI)] = 0.075 mol dm−3, [I(VII)] = 10−5 mol dm−3) and an 17O NMR line broadening technique(30 °C, pH = 4—6, [Cr(VI)] = 1 mol dm−3, [I(VII)] = 0.043 mol dm−3). The catalytic process has been interpreted in terms of the reversible condensation of chromate ions with periodate ions to form chromatoperiodate ions. The rate law is given as: Rc = k1[HCrO4][H4IO6] + k2[HCrO4][H3IO62−] + k3[CrO42−][H4IO6] + k4[CrO42−][H3IO62−], where Rc is defined as the increase in the rate of the oxygen exchange of chromate upon the addition of periodate ions. The catalytic rates were analyzed according to the rate law to obtain the values of the rate constants (k1k4); k1, k2, and k3 are on the order of magnitude of 103—104 mol−1 dm3 s−1, and k4 = 5 mol−1 dm3 s−1 at 0 °C. For the reaction between H3IO62− and CrO42−, the energy and entropy of activation were obtained to be 26 kJ mol−1 and −143 J K−1 mol−1, respectively.
  • Masayasu Iida, Yuri Mizuno, Yasuko Miyagawa
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1531-1537
    Published: 1994
    Released: July 19, 2006
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    An estimation of the peak areas of the 59Co NMR spectra for cobalt(III) complex ions and of the 25Mg spectra for magnesium aqua ions gave population ratios of their hidden ions, which are defined as too strongly interacting with nematic lyomesophases (composed of cationic or anionic surfactants) to contribute to the NMR spectra. The cobalt(III) complex ions used were [Co(NH3)6]3+, [Co(en)3]3+ (en = ethylenediamine), [Co(phen)3]3+ (phen = 1,10-phenanthroline), and [Co(CN)6]3−. It was revealed that appreciable amounts of multivalent ions are present as hidden ions on the lyomesophase, whose sign of charge is opposite to that of the ion in question. For such hydrophilic ions as [Co(NH3)6]3+, [Co(en)3]3+, [Co(CN)6]3−, and magnesium ions, the ions binding to the mesophases are classified into two states based on the NMR spectra: One is an outer-sphere complex (ion pair); the other is a hidden ion. In these systems the hidden ion/total ion population ratios depending on the composition of the surfactant are roughly proportional to the ion pair/total ion population ratios, which are monitored by the magnitude of the quadrupole splitting. For the phen complex, the presence of a hidden ion was observed in the range where the fraction of the anionic surfactant is high; the quadrupole splittings were also observed only in limited composition ranges.
  • Tomoyuki Itaya, Yoshiya Kawabata, Hiroshi Ochiai, Kazuyoshi Ueda, Akir ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1538-1543
    Published: 1994
    Released: July 19, 2006
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    Absorption and fluorescence spectroscopic studies on the charge-transfer (CT) complexation between 9,10-dimethoxyanthracene-2-sulfonate ion (DMACS) and 9,10-anthraquinone-2-sulfonate ion (AQS) in aqueous solution were performed in the presence of poly(allylammonium chloride) (PAAH+Cl), as well as in its absence. No spectroscopic indication of the CT complex was recognized by mixing Na+DMACS (1 × 10−4 M) with Na+AQS (1 × 10−4 M), but the addition of PAAH+Cl to the mixed solution brought about the CT complexation. On the other hand, in the absence of PAAH+Cl, DMACS and AQS also form the CT complex when their concentrations become ca. 1 × 10−3 M. Therefore, the CT complexation between DMACS and AQS in PAAH+Cl solution can be attributed to a close proximity of DMACS–AQS pairs, which results from the electrostatic binding of them by the polyions. The continuous variation method for the CT band indicated that a 1 : 2 (DMACS : AQS) complex and a 1 : 1 complex were preferentially formed in the presence and absence of PAAH+Cl, respectively. The above results show that the high electrostatic potential of PAAH+ affects the complexation, especially the stoichiometry.
  • Tsuneki Ichikawa, Hideyuki Hosokawa, Hiroshi Yoshida
    1994 Volume 67 Issue 6 Pages 1544-1547
    Published: 1994
    Released: July 19, 2006
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    The iron(III) ion in H-mordenite was found to act as a very strong oxidizing agent. It accelerates the conversion of alkyl acetate into alkene and acetic acid by withdrawing an electron from the coordinated alkyl acetate. It also oxidizes water into proton and oxygen, and benzene into benzene radical cation.
  • Nobuyasu Chikamatsu, Tomohiko Tagawa, Shigeo Goto
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1548-1552
    Published: 1994
    Released: July 19, 2006
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    A catalyst derived from oxidation treatment of Mg2Cu alloy was studied in a gas-phase continuous-flow reactor under atmospheric pressure to investigate the specific selectivity for hydrogenation. In order to propose the reaction pathways for hydrogenation of long chain unsaturated ester, reactivities of characteristic functional groups were tested.
    The reactions of ester and aldehyde groups showed higher selectivity to alcohols than to paraffins. We concluded from competitive reactions of two reactants that hydrogenation of unsaturated bond group was inhibited by the adsorption of ester or aldehyde group.
    The effect of partial pressure on each reaction rate was summarized into the Langmuir equation. The main route to unsaturated alcohol and reasons for the increased selectivity to alcohol are discussed.
  • Lian-Xin Dai, Haru Sakashita, Takashi Tatsumi
    1994 Volume 67 Issue 6 Pages 1553-1559
    Published: 1994
    Released: July 19, 2006
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    Pt/KL catalysts prepared by ion exchange (IE), ion exchange followed by the addition of KCl (IE-KCl), incipient wetness impregnation (IWI), and coimpregnation with KCl (IWI-KCl) were compared regarding the aromatization of hexane, and were characterized by transmission electron microscopy, the chemisorption of H2 and NH3, the competitive hydrogenation of toluene and benzene, and the infrared spectroscopy of adsorbed CO. The majority of Pt particles on the various Pt/KL catalysts seem to be highly dispersed inside the zeolite channels. The presence of KCl in the Pt/KL catalysts resulted in a decrease in the acidity of zeolite, giving rise to a reduction in the C1–C5 selectivity, regardless of the method of catalyst preparation. The competitive reaction of toluene/benzene and FT-IR results consistently show that the Pt particles on the IE-KCl catalyst have the most electron-rich sites among the Pt/KL samples examined. The high specific activity for benzene production of the IE-KCl catalyst should be attributed to these Pt particle sites with high electron-donating ability. It is proposed that the terminal adsorption of hexane, resulting in the formation of primary alkyl species, is favorable on electron-rich Pt particles, leading to a 1,6-ring closure, and eventually benzene.
  • Naoki Kuramoto, Masayuki Ueda, Sadakatsu Nishikawa
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1560-1564
    Published: 1994
    Released: July 19, 2006
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    Some equipment for a resonance method was constructed in order to obtain ultrasonic absorption coefficients in a frequency range less than 10 MHz. Using this apparatus, the measurable frequency range was extended down to 2.5 MHz. No relaxational absorption was observed in an aqueous solution of 2-propanol at 2.70 mol dm−3 in the frequency range from 2.5 to 220 MHz. A relaxational absorption was observed in aqueous solutions of n-propylamine in the presence of 2.70 mol dm−3 2-propanol. The frequency dependence of the absorption coefficient was analyzed by a usual Debye-type relaxational equation. Excellent agreement between calculated and experimental values was obtained in the frequency range measured. The relaxational absorption was attributed to the perturbation of equilibria associated with a proton transfer reaction:

    The rate constants and the standard volume change for the first step of the reaction were determined from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. It was found that the forward rate constant decreased and the standard volume change increased when the values were compared with those in the absence of 2-propanol. The results were discussed in relation to water structure and hindrance for the proton transfer reaction by the additives.
  • Akira Matsubara, Fumiko Komada, Hideo Kimizuka
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1565-1571
    Published: 1994
    Released: July 19, 2006
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    The equations of ionic currents in the parallel composite membrane-NaCl system were derived from the phenomenological equations presented by Kedem and Katchalsky.
    The elements of the conductance matrix for the composite membrane system, gαβ, as well as those for the single membrane systems with cation-exchange or anion-exchange membranes, or , respectively, were determined by the measurements of membrane potential, membrane conductance, and salt flux. It was found that gαβc or gαβa for the constituent elements of the composite membrane system was different from or for the single membrane systems, respectively. These differences may be attributed to the situation that gαβc and gαβa represent the intra- and intermembrane transport phenomena, while and represent the former phenomena only. The composite membrane system is characterized by the large cross coefficient which is comparable in the magnitude to the straight coefficients, i.e., gNa·ClgNa·NagCl·Cl. Kedem and Katchalsky have predicted that the strong circulation of current is produced by the partial currents through the element membranes even when the total membrane current is absent. However, because of the large cross coefficient, the partial current through each element membrane due to the conjugate force is nearly canceled by that due to the nonconjugate force.
  • Masashi Tanaka, Hiroaki Matsui, Jun-ichi Mizoguchi, Setsuo Kashino
    1994 Volume 67 Issue 6 Pages 1572-1579
    Published: 1994
    Released: July 19, 2006
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    The crystals of 2-iodoanilinium picrate have three polymorphic forms. The crystal structures of the monoclinic form (form I) and the triclinic form (form II) have been determined by the X-ray diffraction method. The crystals of the third form (form III) are unstable. In forms I and II, 2-iodoanilinium cation and picrate anion form a nearly planar pair of these ions with similar geometry of N–H···O hydrogen bond. In form I the pairs related by a translation are stacked to form the segregated columns, in which the same kinds of ions are stacked with each other, while in form II the anions and cations are alternately stacked to form the continuous columns. The thermochromism of these crystals was studied by measuring the polarized visible and IR absorption spectra and the differential scanning calorimetry.
  • Masao Sakurai, Kunio Nakamura, Katsutoshi Nitta
    1994 Volume 67 Issue 6 Pages 1580-1587
    Published: 1994
    Released: July 19, 2006
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    The densities of dilute aqueous solutions of normal alcohols (from methanol to 1-hexanol) and branched-chain alcohols (2-butanol, 2-methyl-1-propanol, and 2,2-dimethyl-1-propanol) were measured at 5, 15, 25, 35, and 45 °C by means of an oscillating-tube densimeter. The apparent molar volumes of the alcohols in aqueous solutions were determined. The temperature dependences of the limiting partial molar volume, excess partial molar volume, concentration dependence, and methylene group contribution to volume were discussed. An alternative analysis based on the use of specific units instead of molar units was also attempted. The characteristic volumetric behavior of aqueous alcohol solutions is more pronounced for shorter- or branched-chain alcohols rather than hydrophobic alcohols. There is no definitive evidence that so-called hydrophobic hydration around the alkyl groups of alcohol in water is accompanied by a prominent volume change. The unique properties, such as negative partial molar expansion, may originate from the hydrogen-bonding interactions between water and alcohol OH groups.
  • Sinichiro Matsukuma, Hiroshi Kawano, Yoshinori Nibu, Hiroko Shimada, R ...
    1994 Volume 67 Issue 6 Pages 1588-1592
    Published: 1994
    Released: July 19, 2006
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    The effect of pressure on the frequencies and band structures of the Raman active inter- and intramolecular vibrations of the 1,2,4,5-tetrachlorobenzene crystal was studied under hydrostatic pressures upto 4 GPa at 300 K in a gasketed diamond anvil cell. Changes of the Raman frequencies and band structures of the vibrations suggest that the phase transition takes place under about 0.7 GPa. The frequency shift of the intramolecular vibrations induced by pressure was calculated using an intermolecular potential of the atom–atom type based on the two-site molecular exciton theory. The calculation shows that the observed pressure-induced frequency shift is mainly caused by the repulsive force between the chlorine atoms belonging to the adjacent molecules.
  • Gouki Sadakuni, Masayoshi Maehara, Hiroshi Kawano, Yoshinori Nibu, Hir ...
    1994 Volume 67 Issue 6 Pages 1593-1597
    Published: 1994
    Released: July 19, 2006
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    The effect of pressure on the Raman active inter- and intramolecular vibrations of the hexachlorobenzene crystal was studied under hydrostatic pressure up to 5.5 GPa. The Raman frequencies of the inter- and intramolecular vibrations increased monotonically and some bands due to the degenerate intramolecular vibrations were resolved into doublets with increasing pressure. The pressure-induced frequency shift and factor group splitting of the bands due to the intramolecular vibrations were calculated using an intermolecular potential of the atom–atom type. These results show that (1) no phase transition takes place in the crystal under pressure up to 5.5 GPa, (2) the observed pressure-induced frequency shift is mainly caused by the repulsive force between chlorine atoms belonging to the adjacent molecules, and (3) the observed splitting of the bands due to the degenerate intramolecular vibrations is caused by the different intermolecular force acting to the a and b vibrational modes.
  • Yong Wang, Tsukasa Ikeda, Hiroshi Ikeda, Akihiko Ueno, Fujio Toda
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1598-1607
    Published: 1994
    Released: July 19, 2006
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    6-O-, 2-O-, and 3-O-Dansyl-β-cyclodextrins (1, 2, and 3) were synthesized and characterized. Compounds 1 and 2 decrease their fluorescence intensities upon intermolecular complex formation. This property enables 1 and 2 to act as fluorescent sensors, converting binding of organic compounds into fluorescence variations.
  • Masaaki Tabata, Kazuhiko Ozutsumi
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1608-1614
    Published: 1994
    Released: July 19, 2006
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    The metal-substitution reaction of the homodinuclear mercury(II) porphyrin complex, [Hg2(tpps)]2− (H2tpps4− = tetrakis(4-sulfonatophenyl)porphyrin), with copper(II) has been studied by the EXAFS (extended X-ray absorption fine structure) method in an acetate buffer (pH 5.6). The tetrahedral mercury(II) acetato complex (rHg–O = 219 pm, rHg–O = 262 pm) reacts with the porphyrin to form the homodinuclear mercury(II) porphyrin, [Hg2(tpps)(CH3COO)2]4− (rHg–N = 222 pm, rHg–O = 265 pm), with a deformed structure, where two mercury(II) bind to two pyrrole nitrogens from upper and lower sides and pyrrole nitrogens are ruffled. The mercury(II) porphyrin was replaced with the distorted octahedral copper(II) acetato complex (rCu–O = 197 pm, rCu–O = 225 pm) to form the square planar copper(II) porphyrin, [Cu(tpps)]4− (rCu–N = 200 pm). The reaction mechanism of the large catalytic effect of mercury(II) on the copper(II) porphyrin formation is discussed from the structure of Hg2(tpps)2−, and the structure of the heterodinuclear intermediate, [Hg(tpps)Cu]2−, is proposed.
  • Takahide Kimura, Tetsushi Maruyama, Mutsuo Okamura, Takashi Sugiyama, ...
    1994 Volume 67 Issue 6 Pages 1615-1621
    Published: 1994
    Released: July 19, 2006
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    Two derivatives of 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (H4bapta), in which the distance between the chelating functions is changed, have been synthesized. The structure–interaction relationships of their complexation behavior with alkaline earth metal ions are discussed from the viewpoint of their acidity constants and stability constants of their chelate-complexes.
  • Monica Boni, Franco Ghelfi, Ugo Maria Pagnoni, Claudia Zucchi
    1994 Volume 67 Issue 6 Pages 1622-1626
    Published: 1994
    Released: July 19, 2006
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    Methyl 2,2-dichloro or 2-bromo-2-chloro carboxylates were obtained in excellent yields by oxidation–chlorination of 2-(1-haloalkyl)-4-methyl-1,3-dioxolanes with trichloroisocyanuric acid.
  • Galal E. H. Elgemeie, Adel M. E. Attia, Ali M. Elzanate, A. K. Mansour
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1627-1632
    Published: 1994
    Released: July 19, 2006
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    A novel synthesis of 2(1H)-pyridinethione glycosides utilizing 2(1H)-pyridinethiones or their sodium salts and α-tetra-O-acetyl-glucosyl or D-galactosyl bromides as starting components is described.
  • Ken-ichi Sato, Masayuki Bokura, Makoto Taniguchi
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1633-1640
    Published: 1994
    Released: July 19, 2006
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    2,3,6-Tri-O-benzyl-D-myo-inositol, which is a key intermediate of D-inositol 1,4,5-triphosphate, was synthesized from D-glucose without performing any optical resolution by utilizing C2 symmetry. Laminitol and mytilitol were also synthesized from D-glucose via the same key intermediate, 1D-(1,3/2,4)-tetra-O-benzyl-2-C-methyl-5-cyclohexene-1,2,3,4-tetrol.
  • Angelo G. Giumanini, Marco Poiana, Giancarlo Verardo, Paolo Strazzolin ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1641-1645
    Published: 1994
    Released: July 19, 2006
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    The reaction between di-(2-pyridyl)amine and butyl nitrite produced N-nitrosodi-(2-pyridyl)amine, (5-nitro-2-pyridyl)-2-pyridylamine and (3-nitro-2-pyridyl)-2-pyridylamine of which the likely conformations are evinced from spectral data. Structural elucidation of N-nitrosodi-(2-pyridyl)amine in the solid state by X-ray diffraction excluded any substantial contribution of the rings to resonance structures.
  • Akikazu Kakehi, Suketaka Ito, Michiharu Mitani, Masamichi Kanaoka
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1646-1654
    Published: 1994
    Released: July 19, 2006
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    The title compounds, dimethyl 4-thia-1-azatetracyclo[5.4.0.05,11.06,8]undeca-2,9-diene-5,6-dicarboxylates, were prepared in low to moderate yields by the reactions of various 1-pyridinio[(thiocarbonyl)methylide]s and 3-(1-pyridinio)thiophene-2-thiolates with dimethyl acetylenedicarboxylate in chloroform or benzene at room temperature or at the elevated temperature. Some compounds could also be obtained by heating the corresponding dimethyl 10aH-pyrido[1,2-d][1,4]thiazepine-1,2-dicarboxylates once separated from the reaction of pyridinium ylides with the same reagent. These 4-thia-1-azatetracyclo[5.4.0.05,11.06,8]undeca-2,9-diene derivatives were smoothly thermolyzed in xylene at the reflux temperature to afford dimethyl phthalate and the corresponding thiazole derivatives in good yields. The structures of these 4-thia-1-azatetracyclo[5.4.0.05,11.06,8]undeca-2,9-dienes were mainly identified by their physical and spectral inspections together with mechanistic considerations, and confirmed finally by the X-ray analyses of two compounds.
  • Shunsuke Takenaka, Koichi Teshima
    1994 Volume 67 Issue 6 Pages 1655-1658
    Published: 1994
    Released: July 19, 2006
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    This paper describes the thermal properties of 4-nitrophenyl 4-(4-alkoxybenzoyloxy)benzoates and 4-N-[(4-alkoxybenzoyloxy)benzylidene]-4-nitroanilines that have an additional methyl, normal alkoxyl, or hydroxyl substituent on the nitrophenyl group. Methyl and methoxyl groups adjacent to the nitro group reduced the liquid crystalline properties, and derivatives with a long alkoxyl group at the 2 position are nonmesogenic. On the other hand, a hydroxyl group at the 2 position rather enhances the nematic and smectic properties, although a hydroxyl group has a similar volume to the methyl one. The results are discussed in terms of the steric effects of the substituent and electrostatic circumstances around the nitro group.
  • Kazuyasu Sakaguchi, Hiroaki Kodama, Yoshio Ogino, Tommaso Costa, Taker ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1659-1663
    Published: 1994
    Released: July 19, 2006
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    In order to inspect the structural elements of Ser-1 in receptor activation by SFLLRNP (one-letter amino acid code), a ligand peptide tethered to the thrombin receptor, a series of analogs with such replacements as D-Ser, Ala, Thr, and Ac-Ser have been synthesized. These analogs were evaluated for their ability to hydrolyze the phosphoinositide in human neuroblastoma SH-EP cells. It was found that the α-amino group and L-configuration of Ser-1 are very important in the activation of receptors. N-Acetylation or deletion of Ser-1 completely eliminated the activity of SFLLRNP (a half-maximal effective concentration, EC50 = 0.89 μM (1 M = 1 mol dm−3)), and these modifications induced no antagonist activity. Incorporation of D-Ser also drastically diminished the activity, but retained about 50% activity of the maximal response by 100 μM SFLLRNP. The Ser/Ala substitution sustained 30% of the activity of SFLLRNP to elicit a full stimulation. The Ser/Thr substitution, however, enhanced the activity (20%) in spite of its decreased activity (60%) reported for platelet aggregation. These results indicated that the β-hydroxyl group of Ser-1 is important to receptor activation, but not essential. The effect of chemical modifications on the receptor activities of the tethered ligand is discussed with regard to the efficacy between phosphoinositide hydrolysis and biological activities.
  • Tomoaki Yuzuri, Hiroko Suezawa, Minoru Hirota
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1664-1673
    Published: 1994
    Released: July 19, 2006
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    The 1H, 13C, and 15N chemical shifts of various substituted anilides of the carboxylic and sulfonic acids ZNHC6H4Y (Z = C6H5CO, CH3CO, CF3CO, and CH3SO2) and related compounds were correlated with σ and related substituent constants. The ρ-values from the Hammett type plots of the chemical shifts were shown to provide some important information concerning the polarization of the amide chromophore. The solvent effect on ρ showed the fact that the local π-polarization of an amide is strengthened in polar or hydrogen-donating solvents.
  • Takashi Karatsu, Akihide Kitamura, Tatsuo Arai, Hirochika Sakuragi, Ka ...
    1994 Volume 67 Issue 6 Pages 1674-1679
    Published: 1994
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    1-Styrylazulene and 7-isopropyl-1,4-dimethyl-3-styrylazulene (3-styrylguaiazulene) underwent one-way isomerization from the cis to the trans isomer on triplet sensitization. Their triplet states as intermediates of the isomerization were observed by laser flash photolysis. However, their excitation to either the lowest excited singlet state (S1) or the second excited singlet state (S2) by direct irradiation afforded photostationary mixtures comprising 98% of the trans and 2% the cis isomers, which implies the participation of a singlet isomerization path.
  • Shinji Toyota, Tsutomu Miyasaka, Yasutaka Matsumoto, Tamami Matsuo, Mi ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1680-1693
    Published: 1994
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    Enantiomers of the title rotamers were resolved by the diastereomer method with use of optically active camphorsultam. The absolute conformations about the C9–Calkyl single bond were determined by the X-ray analysis of one of the diastereomeric amides. All the samples submitted to the X-ray analysis showed their absolute conformation to be Psc. Specific rotations of the Psc methyl esters of the methyl, methoxy, and chloro compounds at the Na D line were positive, whereas that of the fluoro compound negative. Although the absolute conformation of the methyl compound had been predicted, though not conclusive, to be Msc for the dextrorotatory isomer from calculation, it is proved to be Psc. Optical rotations and CD spectra were measured and these chiroptical properties were compared with each other. The chiral methyl esters showed similar patterns in CD spectra if their absolute conformations are the same, irrespective of the kinds of substituents in the benzene ring. Features of molecular structures of the triptycene compounds are also compared and the effects of substituents on the structural parameters are discussed.
  • Kozo Matsumoto, Toshiaki Yokoo, Koichiro Oshima, Kiitiro Utimoto, Noor ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1694-1700
    Published: 1994
    Released: July 19, 2006
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    Treatment of 2-(trimethylsilyl)silacyclopentane with t-butyllithium in THF–HMPA gave 2-lithio-2-(trimethylsilyl)silacyclopentane in good yield. An addition of alkyl iodides to the lithium compound provided 2-alkyl-2-(trimethylsilyl)silacyclopentanes which were converted into 1-alkyl-1,4-butanediols upon treatment with H2O2–KF and successively with n-Bu4NF. Reaction of 2-lithio-2-(trimethylsilyl)silacyclopentane with aldehydes gave 2-alkylidenesilacyclopentanes, which were transformed into γ-hydroxy ketones by oxidative cleavage of carbon-silicon bonds. 2-Lithio-2-(phenylthio)silacyclopentane, derived from 2-(phenylthio)silacyclopentane and t-butyllithium, afforded alkenyl sulfides having silylalkyl substituent upon treatment with aldehydes. Oxidative cleavage of carbon–silicon bonds followed by hydrolysis of alkenyl sulfide moiety also provided γ-hydroxy ketones.
  • Kuniaki Tatsuta, Shozo Miura, Hiroki Gunji, Tetsuro Tamai, Ryonosuke Y ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1701-1707
    Published: 1994
    Released: July 19, 2006
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    A Z-isomer (4) of 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetic acid, which is the common acyl moiety of clinically useful cephem antibiotics, has been prepared from the aminoisoxazoles through the skeletal rearrangement in several routes. Reaction of 3-amino-5-methoxyisoxazole (7) with alkoxycarbonyl isothiocyanates gave methyl 2-(5-alkoxycarbonylamino-1,2,4-thiadiazol-3-yl)acetates (8), which were converted into the target compound 4 through the reaction of the corresponding keto ester with O-methylhydroxylamime. Compound 4 was prepared similarly from 3-aminoisoxazole (10). Also, O-methylation of 2-hydroxyimino-2-(5-methoxycarbonylamino-1,2,4-thiazol-3-yl)acetate (15) with methyl iodide or dimethyl sulfate in the presence of barium oxide and barium hydroxide octahydrate was found to afford exclusively the desired Z-isomer (14a) of methyl 2-(5-methoxycarbonylamino-1,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetate, which was led to 4.
  • Teruaki Mukaiyama, Isamu Shiina, Hiromi Uchiro, Shu Kobayashi
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1708-1716
    Published: 1994
    Released: July 19, 2006
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    syn- and anti-1,2-Diol units were prepared by using asymmetric aldol reactions of the silyl enol ethers derived from α-alkoxythioacetic S-esters with aldehydes. In the presence of tin(II) triflate, a chiral diamine, and dibutyltin diacetate, (Z)-2-benzyloxy-1-ethylthino-1-(trimethylsiloxy)ethene reacted with aldehydes to afford the corresponding anti-aldol adducts in high yields with excellent diastereo- and enantioselectivities, while syn-adducts were obtained from (Z)-2-(t-butyldimethylsiloxy)-1-ethylthio-1-(trimethylsiloxy)ethene and aldehydes under the same reaction conditions. Thus, both diastereomers can be synthesized in excellent enantiomeric excesses by simply choosing the protective groups of the alkoxyl parts of the silyl enol ethers.
  • Masahiko Yamaguchi, Hyeon-Joo Park, Masahiro Hirama, Kazuhiko Torisu, ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1717-1725
    Published: 1994
    Released: July 19, 2006
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    Selective monodesilylation of 1,8-bis(t-butyldiphenylsilyl)-1,3,5,7-octatetrayne and 1,6-bis(t-butyldiphenylsilyl)-1,3,5-hexatriyne with lithiated phenylacetylene gave unstable 1-(t-butyldiphenylsilyl)-1,3,5,7-octatetrayne and 1-(t-butyldiphenylsilyl)-1,3,5-hexatriyne, respectively. The terminal acetylenes on lithiation added to aldehydes and a ketone giving polyynols in high yields. The reaction was applied to the synthesis of polyyne antibiotics, caryoynencins. Polymerization of the terminal octatetrayne on an ITO-coated glass plate gave a film, which showed conductivity of 10−4 S cm−1 when doped with SO3.
  • Masayuki Takeuchi, Koji Kano
    1994 Volume 67 Issue 6 Pages 1726-1733
    Published: 1994
    Released: July 19, 2006
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    1-Phenylethanol, acetophenone, 2,3-diphenylbutane, and ethylbenzene are produced in the (porphinato)manganese(III)-catalyzed reaction of styrene with NaBH4 in aerobic benzene–ethanol. Chloro(5,10,15,20-tetraphenylporphinato)manganese(III) ([MnIIICl(tpp)]) and chloro[5,10,15,20-tetrakis(2,4,6-trimethylphenyl)porphinato]manganese(III) ([MnIIICl(tmp)]) have been used as the catalysts. It is suggested that the [MnIII(tpp)]-mediated reaction of styrene with NaBH4 yields 1-phenylethyl radical and [MnII(tpp)]. The 1-phenylethyl radical reacts with dioxygen to generate a peroxyl radical, (C6H5)(CH3)CHOO·, which is stabilized by coordinating to [MnII(tpp)]. [MnIII[OOCH(CH3)(C6H5)](tpp)] thus formed may yield [MnIIIOH(tpp)] and acetophenone which is readily reduced to 1-phenylethanol with NaBH4. The coupling and disproportionation reactions of the 1-phenylethyl radicals afford 2,3-diphenylbutane and ethylbenzene, respectively. Slower reaction of styrene observed in the catalysis by [MnIII(tmp)]+ can be interpreted in terms of a steric hindrace in the formation of the radical and [MnII(tmp)]. Similarly, all results obtained for α-methylstyrene can be explained by the formation of the 1-methyl-1-phenylethyl radical which is less reactive than the 1-phenylethyl radical and is free from the interaction with the manganese complex. The reaction mechanism involving the free radicals has been supported by the results on the effects of TEMPO.
  • Yutaka Ikushima, Norio Saito, Osamu Sato, Masahiko Arai
    1994 Volume 67 Issue 6 Pages 1734-1736
    Published: 1994
    Released: July 19, 2006
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    For the Diels–Alder reaction between isoprene and methyl acrylate in supercritical carbon dioxide at 323 K, the solubility parameter of the activated complex was determined as a function of the pressure, ranging from 7 to 20 MPa, in order to study the nature of the complex and the effect of the solvent on the reaction. The relation between the solubility parameter and the ET(30)-scale was examined as well.
  • Hiroshi Awano, Shoji Sakai, Takashi Kuriyama, Yoshihiro Ohba
    1994 Volume 67 Issue 6 Pages 1737-1739
    Published: 1994
    Released: July 19, 2006
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    Quinhydrone crystals were deposited at 2.0 V vs. Ag onto SnO2-coated glass substrates from aqueous solutions of hydroquinone in the presence of NaCl, HCl, or NaOH. The crystals were observed with backscattered image SEM, and characterized with X-ray diffraction and IR spectroscopy. In situ visible absorption spectra were measured and a mechanism of deposition is discussed.
  • Ryouta Yanagi, Chinami Matui, Mituru Chinda, Yasushi Yamamoto
    1994 Volume 67 Issue 6 Pages 1740-1742
    Published: 1994
    Released: July 19, 2006
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    The stereoisomers of 2-butanone O-trimethylsilyloxime were observed as separate peaks, the intensity ratio being 1 : 3, by high resolution GC equipped with a capillary column. The peak with intensity 3 was assigned to the Z isomer of oxime bond and the intensity ratio corresponded to the stereoisomer ratio of 2-butanone oxime. Silanes including plural oxime groups also gave separate stereoisomer peaks corresponding to the isomer ratio of 2-butanone oxime.
  • Shuji Emori, Kazutoshi Sadakata
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1743-1745
    Published: 1994
    Released: July 19, 2006
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    Dicopper(II) hydroxide tris(pyrazolide)s Cu2(OH)(4-Xpz)3 (pz = pyrazolide ion; X = H, CH3, Cl, Br) and Cu2(OH)(4-Xpz)3(4-XpzH)2 (X = Cl, Br) were prepared and characterized by means of magnetic susceptibility and IR spectroscopy. Their magnetic-moment values increased in the substituent sequence X = CH3 < H < Br ≈ Cl, and were correlated with the basicities and coordinating angles of the pyrazolido ligands.
  • Shizuaki Murata, Yoshiyuki Ido
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1746-1748
    Published: 1994
    Released: July 19, 2006
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    Palladium bis(trifluoromethanesulfonate) is usually prepared from the reaction of palladium dinitrate or diacetate and trifluoromethanesulfonic acid. Reactions of palladium bis(trifluoromethanesulfonate) with various ligands (L and/or X) give corresponding palladium(II) complexes, such as [Pd(CF3SO3)2L2] and [PdX2L2].
  • Miyoko Ochi, Hitoshi Furusho, Jun Tanaka
    1994 Volume 67 Issue 6 Pages 1749-1752
    Published: 1994
    Released: July 19, 2006
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    Linear oligoaniline derivatives were prepared by the reaction of aromatic amines and phenols using various titanium alkoxides as condensing agents. The oligomers obtained were silver white microscopic crystals. Titanium alkoxides used were titanium alkoxide or titanium alkoxide aryloxide and the latter showed high dehydration condensation activity in comparison with the usual titanium alkoxides.
  • Masaki Matsui, Michinori Tsuge, Katsuyoshi Shibata, Hiroshige Muramats ...
    1994 Volume 67 Issue 6 Pages 1753-1755
    Published: 1994
    Released: July 19, 2006
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    1,1-Bis[4-(dimethylamino)phenyl]-1-alkanols were found to show photochromism.
  • Nobuo Sakairi, Shunya Takahashi, Feng Wang, Yoshihito Ueno, Hiroyoshi ...
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1756-1758
    Published: 1994
    Released: July 19, 2006
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    Treatment of 1,6-anhydro-2,3-O-endo-benzylidene-β-D-mannopyranose derivatives with trimethylamine–borane (1/1)–aluminium chloride resulted in highly regioselective fission of the cyclic acetals to give the corresponding 2-O-unprotected-3-O-benzyl derivatives. Trifluoromethanesulfonylation of these, followed by nucleophilic substitution, afforded 2-azido-2-deoxy derivatives in good yields.
  • Kazushi Omote, Yoshio Aso, Tetsuo Otsubo, Fumio Ogura
    1994 Volume 67 Issue 6 Pages 1759-1761
    Published: 1994
    Released: July 19, 2006
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    Tellurium tetraethoxide reacts with primary thioamides at room temperature, forming nitriles in high yields. On the other hand, the reactions with amides are largely temperature-dependent, giving predominantly esters at 80 °C and nitriles at a higher temperature. Similarly, tellurium tetraethoxide readily induces the C–N bond cleavage of ureas to give carbamates and amines.
  • Ryoka Matsushima, Hirotaka Mizuno, Atsushi Kajiura
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1762-1764
    Published: 1994
    Released: July 19, 2006
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    The quantum yields for the photochemical conversion of 2-hydroxy-4′-methoxychalcone into the flavylium ion are in the range of 0.25—0.35 in acetic acid and 0.14—0.2 in aqueous ethanol at pH 2, depending on the wavelength of UV light. The quantum yields are essentially constant against any changes in the light intensity, temperature, or substrate concentration, which is a favorable feature regarding use as a convenient chemical actinometer. A one-photon mechanism involving excited-state proton-transferred tautomer is proposed.
  • Tomihiro Nishiyama, Hiroshi Kishi, Kouji Kitano, Fukiko Yamada
    Type: Accounts
    Subject area: AI
    1994 Volume 67 Issue 6 Pages 1765-1768
    Published: 1994
    Released: July 19, 2006
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    Oxazolidines, obtained by the condensation of aldehydes with 2-anilino-1-alkanols, react with the Reformatsky reagent derived from ethyl bromoacetate under mild reaction conditions to afford ethyl 3-(2-hydroxyalkyl)aminoalkanoates.
  • Hirochika Sakuragi, Toshiya Koyama, Mamoru Sakurazawa, Norimichi Yasui ...
    1994 Volume 67 Issue 6 Pages 1769-1772
    Published: 1994
    Released: July 19, 2006
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    Irradiation of a bichromophoric 1-(o-cyanobenzyloxy)-2-(p-methoxyphenyl)-2-butene (1a) in cyclohexane gave an isoquinoline derivative, 8-methoxy-6-methyl-11,13-dihydro[2]benzoxepino[5,4-c]isoquinoline (2a). The structure was determined by X-ray analysis. The formation of 2a can be accounted for by the initial cycloaddition of 1a in the excited singlet state between the C=C double bond and C≡N triple bond, followed by cleavage of the resulting azetine ring and recyclization.
  • Li Fan, Kaoru Fujimoto
    1994 Volume 67 Issue 6 Pages 1773-1776
    Published: 1994
    Released: July 19, 2006
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    Pd/TiO2 catalyst reduced by flowing hydrogen at 500 °C, appearing with a strong SMSI effect, was found to be an active and selective catalyst for hydrogenation of CO2 to methanol while the catalyst showed poor activity and selectivity if it was reduced below 400 °C.
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