Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 68 , Issue 8
Showing 1-44 articles out of 44 articles from the selected issue
  • Akira Odani, Tetsuo Sekiguchi, Hisashi Okada, Shin-ichi Ishiguro, Osam ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2093-2102
    Published: 1995
    Released: July 09, 2006
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    Calorimetric and spectroscopic investigations have been carried out on the stacking interactions between nucleosides or nucleotides (NMP) and platinum DNA intercalators and other planar platinum(II) complexes with heteroaromatic ligands (L). Pt(L)(diamine) (L = 1,10-phenathroline (phen), its methyl and nitro derivatives, 2,2′-bipyridine; diamine = ethylenediamine (en), L-2,3-diaminopropionate) reacts with NMP (=adenosine 5′-monophosphate (AMP), guanosine 5′-monophosphate (GMP), inosine 5′-monophosphate (IMP), cytidine 5′ -monophosphate (CMP); nicotinamide adenine dinucleotide (NAD), adenosine, cytidine) to give the Pt(L)(diamine)–(NMP)n adducts (n = 1, 2) with log K1 = 1.63—3.00 and log K2 = 1.47—2.51 at 25 °C at ionic strength = 0.1 mol dm−3 (NaCl). The 1 : 1 adduct formation mainly depends on the enthalpy change ΔH1° = −6.5 — −26.2 kJ mol−1, and the entropy change (ΔS1° = −38—20 J mol−1 K−1) makes a negative or small contribution. 1H NMR upfield shifts observed for the Pt(phen)(en)–NMP systems have substantiated the presence of stacked adducts in dilute aqueous solution, whereas diquat, a dicationic organic molecule, did not cause appreciable shifts, and hence the adduct formation was negligible. NAD was found to interact with Pt(phen)(en) through the adenine moiety. 195Pt NMR signals of Pt(phen)(en) in water suffered downfield shifts upon addition of NMP, the Δδ1 values being in the order NAD ≥ AMP ≈ GMP > IMP. This indicates that stacking causes an electron density decrease of the Pt(II) center. Linear relationships have been detected between the ΣΔHn° values and the absorption coefficients εn of the difference spectra in the charge transfer region and between ΣΔHn° and 195Pt NMR shift differences Δδn. These observations serve as evidence for the electronic effects of stacking interactions on the stacked rings and the central Pt(II) ion.
  • Naoki Asao, Tadao Uyehara, Naofumi Tsukada, Yoshinori Yamamoto
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2103-2111
    Published: 1995
    Released: July 09, 2006
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    Amidocuprate(I) reagents {Li[Cu(NR2)2]} and higher order cyanocuprates(I) {Li2[Cu(CN)(NR2)2]} have been developed as a new class of nitrogen nucleophiles. These reagents underwent regioselective 1,4-additions to α,β : γ,δ-dienoates, whereas NHR2 gave a 1,6-addition product and the lithium reagent LiNR2 afforded a mixture of 1,4- and 1,2-addition products. The amidocuprates(I) were added to chiral α,β : γ,δ-dienones having a 8-phenyl-p-menth-3-yl or a 10,2-bornanesultam chiral auxiliary in order to produce 1,4-adducts in good to high diastereoselectivity. The addition of Li[Cu{N(Bn)(TMS)}2] and Li2[Cu(CN){N(Bn)(TMS)}2] to 8-phenyl-p-menth-3-yl 5-phenyl-2,4-pentadienoate or N-(5-phenyl-2,4-pentadienoyl)-10,2-bornanesultam produced an (R)-chirality at the β-position. The 1,4-addition of Li2[Cu(CN){N(Bn)(TMS)}2] to the bornanesultam, followed by trapping with acetaldehyde, gave the α-(1-hydroxyethyl)-β-amino derivative as a single isomer in good yield. This three-component coupling was used in an asymmetric synthesis of a β-lactam.
  • Takako Fujimoto, Ryoji Yanagihara, Kenji Kobayashi, Yasuhiro Aoyama
    1995 Volume 68 Issue 8 Pages 2113-2124
    Published: 1995
    Released: July 09, 2006
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    Tetrasulfonate derivatives of calix[4]resorcarene (calix[4]arene derived from resorcinol) (1) form 1 : 1 complexes with highly hydrophilic guest molecules, such as ethers, alcohols, ketones, and sulfoxides, in water. The affinities of three types of the guests increase in the order CH3–X–CH3 < (–CH2CH2–X–)2 < CH3–X–CH2CH2–X–CH3 (X = O, CH(OH), C=O, or S=O), reflecting the importance of multiple host-guest interactions. The binding constants (K) with respect to X increase in the order O < CH(OH) < C=O < S=O or CH(OH) < O < C=O < S=O. As for the effects of substituents Y on 2-C of the benzene rings of the host, both 1b (Y = CH3) and 1c (Y = OH) exhibit higher binding capabilities than does the parent host 1a (Y = H). Thus, the present complexation is promoted by electron-withdrawing residue (X) in the guests and electron-donating substituents (Y) in the host. The binding of CH3–X–CH3 (X = C=O or S=O) to hosts 1ac is characterized by favorable enthalpy changes and unfavorable entropy changes. These results, coupled with NMR data, indicate that the driving force of the present complexation is a C–H···π interaction between C–H bonds of a guest as soft acids and benzene rings of the host as soft bases.
  • Masanobu Ajioka, Katashi Enomoto, Kazuhiko Suzuki, Akihiro Yamaguchi
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2125-2131
    Published: 1995
    Released: July 09, 2006
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    The direct condensation polymerization of lactic acid has been studied, and polylactic acid having a high molecular weight was obtained in an organic solvent without any isolation of the intermediate, dilactide. The molecular weight was raised up to 300000 through the examination of several reaction conditions, e.g., solvent, catalyst, etc. Thus-obtained high-molecular-weight polylactic acid can be processed into films and molded products having sufficient strength and toughness. The characteristic features of polylactic acid obtained by this direct process were compared to that obtained by the conventional ring-opening polymerization process. In addition, copolymerization of lactic acid with a variety of D/L ratios is discussed.
  • Milan Dj. Petkovic, Slobodan K. Milonjic, Vera T. Dondur
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2133-2136
    Published: 1995
    Released: July 09, 2006
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    The stability of colloidal alumina in the presense of selected inorganic anions (NO3, Cl, I, SO42−, and [Fe(CN)6]3−) has been studied by a potentiometric titration technique. The dependencies of the critical concentrations of coagulation on the solution pH were determined for all studied anions, as well as the regions of coagulation and stability of the system. It has been shown that the critical concentrations of coagulation decrease along with an increase in the pH, which is interpreted by coagulation theory and the electrical layer model. Differences between the critical concentrations of coagulation at the same pH value for monovalent anions are explained based on their hydration degree differences, while the discrepancies between the experimental data and the theoretical values given by the Schultze–Hardy law are interpreted in light of specific sorption of sulfate anions and the general specificity of the investigated system. Based on a parallel stability study of colloidal alumina prepared in the laboratory and of a commercial product, the same stability behavior in the presence of KCl has been found.
  • Elavathingal Itteera Tessy, Animesh Kumar Rakshit
    1995 Volume 68 Issue 8 Pages 2137-2141
    Published: 1995
    Released: July 09, 2006
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    The phase diagram of a nonaqueous microemulsion system containing cyclohexane/Triton® X-100/DMF was determined at 40 °C. The one-phase microemulsion area increased in the presence of a cosurfactant. Physical properties like viscosity, adiabatic compressibility, specific conductance, and contact angle are discussed at a surfactant concentration of 15% to explain the microstructure. A cyclohexane/TX 100+1-propanol/DMF system shows percolation, though not high, with ca. 0.15 mole fraction of DMF. Contact angle measurements of cyclohexane/TX 100/DMF at various cyclohexane/DMF ratios show a DMF continuous system. In the presence of a cosurfactant, the contact angle values show a continuous change indicating an 0/DMF to bicontinuous to DMF/0 structure. NaI does not introduce a three-phase liquid system.
  • Nobuaki Kanamaru
    1995 Volume 68 Issue 8 Pages 2143-2150
    Published: 1995
    Released: July 09, 2006
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    The theory of the rotational effects on radiationless transitions in typical azines is extended to include the hyperfine (hf) interaction term, while examining their deuterium (isotope) effects on the decay behaviors after excitation into the rotational levels belonging to their S10 levels, i.e. their ground vibrational levels of S1 states. The Fermi-contact hf term is shown to be enough to endorse the coupling between rotational levels that are different either in symmetries or in some angular-momentum quantum numbers. The deuterium (D) effect is found to be not simply described as a conventional isotope effect: Changes by D substitution are brought about in densities of triplet states and hf coupling terms, as well as molecular symmetry groups. While interpreting the experimental data, modifications of the schemes are made from those presented earlier in this series.
  • Naoki Satoh, Akira Naito, Keisaku Kimura
    1995 Volume 68 Issue 8 Pages 2151-2157
    Published: 1995
    Released: July 09, 2006
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    High-resolution 1H NMR spectra of terephthalic acid (TPA) ultrafine particles (UFP’s) were obtained under the conditions of rapid Brownian motion of UFP’s in liquid CCl4 (UFP-NMR method). Six signals were resolved in the range of 6.85 to 7.65 ppm with respect to an tetramethylsilane. These were assigned to aromatic protons, even though only a single signal at 8.15 ppm was obtained from molecular dispersion of TPA in acetone. TPA-UFP dispersions were prepared by a vacuum evaporation technique combined with a cold matrix-isolation method. Particle sizes obtained were ca. 15 nm by a dynamic laser scattering method. The results from UFP-NMR method are discussed in conjunction with those from solid state 1H NMR via a CRAMPS method and with a conventional liquid state NMR of TPA.
  • Michio Yamanaka, Hitoshi Matsuki, Shoji Kaneshina
    1995 Volume 68 Issue 8 Pages 2159-2164
    Published: 1995
    Released: July 09, 2006
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    Densities of aqueous solutions of mixtures of dibucaine hydrochloride (DCHC), a local anesthetic, and dodecyltrimethylammonium chloride (DTAC) were measured as functions of total molality. The apparent molar volumes of the mixtures were calculated from the density data. The molar volumes in the monomeric and micellar states were evaluated from the dependence of the apparent molar volume on the total molality. The critical micelle concentration (cmc) of the mixtures was determined from the break point of the apparent molar volume vs. the total molality curves, while the micellar composition was evaluated from the dependence of the cmc on the mole fraction of DTAC in the mixture. The composition diagram of micellization has a swollen cigar shape, slightly distorted in the composition range near the DTAC component; such a distortion indicates slightly non-ideal mixing between the hydrophobic groups of DCHC and DTAC molecules in the micelle. However, the molar volume of micellar state varies depending upon the micellar composition along a straight line connecting the molar volumes of DCHC and DTAC. Moreover, the volume of micelle formation is smaller for DCHC, which has larger monomer and micellar volumes than DTAC, and increases linearly with increasing DTAC composition in the micelle. Therefore, the bulky structure of the hydrophobic part of the DCHC molecule affects both the miscibility and the volume behavior in the DCHC–DTAC mixed micelles.
  • Maw-Ling Wang, Chin-Chou Ou, Jing-Jer Jwo
    1995 Volume 68 Issue 8 Pages 2165-2174
    Published: 1995
    Released: July 09, 2006
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    The reaction of benzoyl chloride (PhCOCl) and sodium dicarboxylate (R(COONa)2) catalyzed by an inverse-phase-transfer catalyst (IPTC) in the two-phase medium H2O/CH2Cl2 was investigated. Pyridine 1-oxide (PNO) was used as the inverse-phase-transfer catalyst. Ten dicarboxylates, namely oxalate, malonate, maleate, succinate, adipate, nonanedioate, fumarate, phthalate, isophthalate, and terephthalate, were selected for study. In general, the observed mixed products included mono- and bis(benzoyloxycarbonyl) compounds, benzoic anhydride and benzoic acid, depending on the molecular structure of the dicarboxylate ion. Dicarboxylates of four types were classified according to distribution of products. The reaction rate is strongly affected by PhCOCl and R(COONa)2 due to their influence on the distribution of PNO in the organic phase. A mechanistic interpretation of the experimental data is presented.
  • Takeshi Kawai, Yoichi Yasuda, Kijiro Kon-no
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2175-2177
    Published: 1995
    Released: July 09, 2006
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    Time dependence of the conversion of acrylamide (AAm) initiated with potassium peroxodisulfate (KPS) was examined at various [AAm] and [KPS] in W/O microemulsions of 1,4-bis(2-ethylhexyl) sodium sulfobutanedioate in cyclohexane media at 45 °C. The rate of polymerization (Rp) calculated from the conversion-time profiles yielded the following equation: Rp ∝ [AAm]1.0[KPS]0.5. From these values of reaction orders for AAm and KPS, it was found that the polymerization of acrylamide in W/O microemulsions can be regarded as normal radical polymerization and biradical termination between polymer radicals.
  • Katumitu Hayakawa, Satoshi Shinohara, Shin-ichiro Sasawaki, Iwao Satak ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2179-2185
    Published: 1995
    Released: July 09, 2006
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    Solubilization data for the water-insoluble dyes o-(2-amino-1-naphthylazo)toluene (OY) and 1-pyrenecarbaldehyde (PyA) in mixed solutions of anionic polyelectrolyte and a cationic surfactant are reported. The polymers used were sodium dextran sulfate (DxS) and the sodium salt of poly(styrenesulfonic acid) (PSS). The surfactants used were dodecyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB). DxS exhibited a highly cooperative binding of the surfactant ions, while binding to PSS occured at lower surfactant concentrations, but was less cooperative. DxS/surfactant complexes had a larger solubilization capacity per bound surfactant ion for both OY and PyA than did PSS/surfactant complexes. The standard Gibbs energy changes for solubilization in DxS/DTAB were determined to be 4.0 kJ mol−1 for OY and 5.4 kJ mol−1 for PyA; the values in PSS/DTAB were 6.5 kJ mol−1 for OY and 9.3 kJ mol−1 for PyA. The solubilization capacities and standard Gibbs energy changes of polyion/surfactant complexes strongly relate to the binding mode of the surfactant. The differences in the solubilization capacities and standard Gibbs energy changes between polyion/surfactant complexes and DTAB or TTAB micelles, and between OY and PyA, are discussed in relation to the aggregate size and solubilizate location.
  • Fulvio Corradini, Andrea Marchetti, Mara Tagliazucchi, Lorenzo Tassi, ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2187-2191
    Published: 1995
    Released: July 09, 2006
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    Static dielectric constants (ε) were determined for the 1,2-dichloroethane (DCE, 1)/2-chloroethanol (CE, 2) binary solvent system at 19 temperatures ranging from −10 to +80 °C and in the whole composition range expressed by the mole fraction 0 ≤ X1 ≤ 1. The experimental values have been fitted to some equations that could be usefully employed for predictive ε calculations. Furthermore, the excess mixing properties (εE) have been evaluated in order to point out the presence of solvent–cosolvent adducts in the binary mixtures mentioned above. The values of εE have been generally found to be negative and only slightly positive under a few experimental conditions in the CE rich-region, thus giving evidence of a close interaction network probably via hydrogen bonding as well as other interactions of every kind in this solvent system.
  • Hirofumi Nakamura, Masahide Terazima, Noboru Hirota, Satoshi Nakajima, ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2193-2202
    Published: 1995
    Released: July 09, 2006
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    Charge separated ion-pair (IP) states formed from three distance-fixed photosynthetic triads were studied by the time-resolved EPR method. Upon photoexcitation of the triads in THF at 77 K, small and narrow signals were observed at the central parts of broad EPR spectra due to the excited triplet states of the chromophores. These signals were assigned to secondary, fully charge separated IP states by the simulation based on the spin-correlated radical pair mechanism. Time dependence of the TREPR signals indicates that charge separation occurs in the singlet manifold as in the case of the photoexcited state dynamics at room temperature. Estimated electron exchange interactions, J, are in the order of 10−2—10−3 mT, which is in line with the observed long lifetimes of the IP states.
  • Masataka Kuroda, Kazuto Yamazaki, Tooru Taga
    1995 Volume 68 Issue 8 Pages 2203-2206
    Published: 1995
    Released: July 09, 2006
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    A conformational analysis of tetragastrin in an aqueous solution was carried out by a Monte-Carlo simulation, assuming a molecular model in a continuous media. The hydration energy of the peptide was evaluated from a calculations of the peptide–water accessible surface area. The tetrapeptide conformers in the low-energy state take an extended form, in which the two aromatic rings on both termini of the peptide are apart. The extended conformation in which the hydrophilic portions are exposed to solvent water is quite different from that in DMSO.
  • Masayuki Morita, Hironari Takase, Masashi Ishikawa, Yoshiharu Matsuda
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2207-2213
    Published: 1995
    Released: July 09, 2006
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    Poly(2,5-dihydroxyaniline), or poly[imino(2,5-dihydroxy-1,4-phenylene)] (PAn(OH)2), films were prepared by electropolymerization of 2,5-dimethoxyaniline (DMA), followed by electrochemical hydrolysis of methoxyl groups in an acidic solution. The films gave responses characteristic of a hydroquinone/quinone couple in aqueous solutions, suggesting that many hydroquinone units are introduced in the polymer structure. Although the polymer in the reduced state consisted of aniline units with substitutions by hydroxyl groups, its redox process is based on the reaction of hydroquinone/quinone couple in its structure, not on the doping/undoping in the aniline unit. Electrochemical redox processes were examined on the PAn(OH)2-modified platinum electrode. The polymer films showed electrocatalytic activities for such redox reactions as the oxidation of [Fe(CN)6]4−, Fe2+, and [Co(NH3)6]2+ in aqueous solutions. Some interactions were suggested between the hydroquinone/quinone site or the aniline unit in the polymer and the redox active metal complexes in the solution and/or in the polymer.
  • Manabu Kitazawa, Mitsuo Takahashi, Tatsuo Wada, Hiroyuki Sasabe, Masay ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2215-2224
    Published: 1995
    Released: July 09, 2006
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    L-2-Pyrrolidone-5-carboxylic acid (L-PCA) is a novel nonlinear optical material with the optical transparent range down to the UV region. L-PCA molecules are hydrogen-bonded to form the three-dimensional network in a crystal. It has been thought that the network of hydrogen bonds influences on the stability of the crystal structure as well as the second-order optical nonlinearity. We have performed the theoretical evaluation of the contributions of the intermolecular hydrogen bonds to structural stability and second-order nonlinearity in the L-PCA crystals by use of the molecular orbital calculation methods. In the calculation of CNDO/S-SECI (singly excited configuration interaction) method, it is shown that the primary contributor to the molecular hyperpolarizability (β) is an nπ → π* transition in the amide moiety of L-PCA molecule. The calculation of intermolecular interaction energies for L-PCA clusters by the ab initio STO-3G method indicates that the hydrogen bonds in the crystal contribute to the stabilization of the crystal structure by −7.8 to −9.1 kcal mol−1 for one hydrogen-bond formation. Furthermore, it is also confirmed by CNDO/S-CHF (coupled Hartree–Fock) calculation that the hydrogen-bonding interactions induce the enhancement of the βXYZ value, a unique β component contributing to the nonlinear optical coefficient (d14). On the basis of the calculated β components, d14 can be estimated to be d14 = 0.30 pm V−1 by the oriented-gas model. This value is in good agreement with the experimental result. Therefore, these results verify that the hydrogen bonds between L-PCA molecules contribute not only to the physical and chemical stability of L-PCA crystals but also to the enhancement of β values. This theoretical estimation shows the effectiveness of the hydrogen bonds in second-order nonlinear optical crystals.
  • Toshiyuki Takayanagi, Atsushi Yokoyama
    1995 Volume 68 Issue 8 Pages 2225-2232
    Published: 1995
    Released: July 09, 2006
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    The photodissociation dynamics of the model CH2XY (X and Y are halogen atoms) molecule was studied using a time-dependent quantum mechanical method in two dimensions. Simple functional forms were employed as two diabatic potential energy surfaces which correspond to the excited states of C–X (n–σ*) and C–Y (n–σ*). Bond selectivity in the photodissociation is quantitatively examined in terms of the coupling strength between the two surfaces. A method to predict the bond selectivity in the photodissociations is also discussed on the basis of the results of ab initio molecular orbital calculations.
  • Tokutaro Komatsu, Hirohiko Sato, Toshikazu Nakamura, Nozomu Matsukawa, ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2233-2244
    Published: 1995
    Released: July 09, 2006
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    A crystal-structure analysis and a band calculation, as well as conductivity, thermoelectric power, ESR, and static susceptibility measurements were performed on the new BEDT–TTF salt, θ-(BEDT–TTF)2Cu2(CN)[N(CN)2]2. This salt has a unique polymerized anion comprising infinite Cu–N(CN)2–Cu double helices bridged by disordered CN groups. Although the two-dimensional arrangement of crystallographically equivalent BEDT–TTF+0.5 cations provides a two-dimensional closed Fermi surface within the tight-binding approximation, this salt is semiconductive even at room temperature, probably due to a strong electron correlation in this system. A semiconductor–semiconductor transition has been observed around 220 K. Below 220 K the electronic system is represented as a Mott insulator and a two-dimensional Heisenberg antiferromagnet. Rapid decreases in the ESR line width and spin susceptibility below 50 K indicate the existence of an additional magnetic transition.
  • Toshiyuki Takayanagi, Atsushi Yokoyama
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2245-2251
    Published: 1995
    Released: July 09, 2006
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    Classical trajectories for four-centered HF elimination from vinyl fluoride have been calculated directly from ab initio molecular orbital results at the HF/3-21G level of theory, without the construction of an analytical potential energy function. The excess energy dependences of the product energy distributions and vector correlations were calculated. The calculated results were compared with available experimental data and qualitative agreements were obtained. However, in order to obtain quantitative agreements, trajectory analyses at a more accurate ab initio level of theory seem to be necessary.
  • DJahan B. Raoof, Seyed M. Golabi
    1995 Volume 68 Issue 8 Pages 2253-2261
    Published: 1995
    Released: July 09, 2006
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    The preparation and aqueous electrochemistry of a carbon-paste electrode, modified by 1,4-naphthoquinone and some of its derivatives are described. From a calculation of the half-wave potential as a function of the pH, potential-pH diagrams were constructed for each compound. The values of the formal potentials and the pKa′ of some different redox and acid-base couples involved at various solution pHs were obtained. The influence of such substituents as methyl-, hydroxy-, chloro-, and amino- concerning the electrochemical behavior of surface 1,4-naphthoquinone is described. The electrochemical behavior of such electrodes was examined in buffered borate solutions and the formation of a complex between borate anion and o-naphthalenediols was characterized. Finally, the range of the pH at which the electrode function is consistent was determined.
  • Tsutomu Mizuta, Kenji Kusakari, Mari Hashimoto, Katsuhiko Miyoshi
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2263-2269
    Published: 1995
    Released: July 09, 2006
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    The trans isomer of aminomethanechlorobis(1,2-diaminoethane)cobalt(III), trans-[CoCl(NH2Me)(en)2]2+, was prepared from trans-[CoCl(NO2)(en)2]+ by a two-step reaction in which Cl was replaced with an NH2Me and then the remaining NO2 was replaced with a Cl. The configuration was confirmed by X-ray crystal analysis, and structural comparison was made with its cis isomer. The crystals have the formulae, trans-[CoCl(NH2Me)(en)2]Cl(ClO4) and cis-[CoCl(NH2Me)(en)2]Cl2. The crystallographic data are as follows; Monoclinic, P21/c, a = 11.515(1), b = 7.421(2), c = 17.257(1) Å, β = 99.220(8) °, V = 1455.6(5) Å3, Z = 4, and R = 0.043 for the former, and Orthorhombic, Fdd2, a = 26.64(1), b = 27.26(1), c = 7.570(2) Å, V = 5497(3) Å3, Z = 16, and R = 0.057 for the latter. The Co–Cl bond of the trans complex is longer than that of the cis complex. It was found that the bulkiness of the Me group effects the trans Co–Cl bond through one of the two flexible equatorial en chelate rings. The kinetic data of an aquation reaction of the trans and the cis complexes show that the Cl of the trans complex is substituted more readily than that of the cis is.
  • Thomas Schönherr, Mutsuyoshi Itoh, Akio Urushiyama
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2271-2276
    Published: 1995
    Released: July 09, 2006
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    The polarized absorption spectra of trans-[Cr(CN)2(NH3)4](ClO4), which crystallizes in the orthorhombic space group Pna21, were measured in spin-allowed quartet () and intraconfigurational spin-forbidden doublet () transition regions. Gaussian deconvolution of the quartet bands and detailed vibronic assignments of the spin-forbidden doublet transitions yielded a total of seven electronically excited states. These have been used for ligand field calculations in terms of the angular overlap model. By using a π-orbital reduction factor of τ = 0.984 as well as a negative eπ value for the acceptor ligand CN (−930 cm−1) we were able to reproduce the d-level scheme in high accuracy. The results compare well with our findings for the related monocyano complex.
  • Dinesh C. Nambiar, Vijay M. Shinde
    1995 Volume 68 Issue 8 Pages 2277-2279
    Published: 1995
    Released: July 09, 2006
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    Tris(2-ethylhexyl) phosphate (T2EHP) is used for the extraction of cadmium salicylate. The experimental conditions are established and the probable extractable species is ascertained by log D–log C plots. Microgram amounts of cadmium are determined in the Tris(2-ethylhexyl) phosphate phase with 1-(2-pyridylazo)-2-naphthol as the chromogenic agent. The proposed method is used for the separation of cadmium(II) from zinc(II), mercury(II), lead(II), bismuth(III), antimony(III), and thallium(III) and used for the estimation of cadmium in industrial waste water, kidney stone, cigarettes, and alloy samples.
  • Tomosuke Ishizuki, Tomoaki Murakawa, Tetsuya Yamada, Akio Yuchi, Hirok ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2281-2285
    Published: 1995
    Released: July 09, 2006
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    X-Ray crystal structures have been determined for two compounds obtained by the coupling reaction of 2-pyridinediazonium salt and m-methoxyphenol, viz., 3-methoxy-4-(2-pyridylazo)phenol (1) and 5-methoxy-2-(2-pyridylazo)phenol (2). The 2-pyridylazo and 2-thiazolylazo compounds having o-methoxy and p-hydroxy groups, such as 1, have lower pKa values and lower affinities for or higher selectivities to metal ions than corresponding o-hydroxy isomers. The resulting bis complexes with metal ions show molar absorptivities greater than 105.
  • Toshiaki Yonemura, Hiroshi Kawaguchi, Kimi Shibuya, Kaori Murakami, To ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2287-2292
    Published: 1995
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    The diethylenetriamine (dien) cobalt(III) complex with a three-membered ring, fac-trans(NH, O)-[Co(CH2SCH2COO)(dien)]+ (1), has been prepared in an aqueous solution by the photodecarboxylation of u-fac- (2) or s-fac-[Co(2,2′-thiodiacetato)(dien)]+ (3). Perchlorate salt of 1 was subject to spontaneous resolution, and the crystal structure and absolute configuration for the isomer were determined by X-ray diffraction. The crystal is monoclinic, space group P21, a = 6.962(1), b = 13.411(1), c = 7.663(1) Å, β = 101.921(8)°, V = 700.1(2) Å3, Z = 2, and R = 0.032. The formation of the three-membered ring introduces a significant distortion into the octahedral coordination around the Co atom (∠C–Co–S = 49.4(1)°), although the bond lengths in the ring are within the range normally observed for other complexes. For the isomer the chiral configuration is regulated to ΔΛΔ and R for the sulfur atom. The racemization rate of 1 is very fast in water and DMSO. The position of the first d–d band of 1 is red-shifted by 1600—1100 cm−1 relative to those of 2 and 3. The photolysis of mer-[Co(3,3′-thiodipropionato)(dien)]+ did not give a similar product to 1.
  • Masahiko Inamo, Mikio Hoshino, Kiyohiko Nakajima, Sen-ichi Aizawa, Shi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2293-2303
    Published: 1995
    Released: July 09, 2006
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    The Cr(III) porphyrin complexes [Cr(tpp)(Cl)(H2O)] (1) and [(Cr(tpp)(Cl)(py)] (2) (tpp represents the dianion of 5,10,15,20-tetraphenylporphine) crystallized from a chloroform–toluene mixture in the tetragonal space group I4, Z = 2, a = 13.559(5), b = 13.559(5), c = 9.770(3) Å, V = 1796(3) Å3, and from a dichloroethane–toluene mixture containing a small amount of pyridine (py) in the monoclinic space group P21/n, Z = 4, a = 14.655(5), b = 23.498(4), c = 13.152(2) Å, β = 101.54(1)°, V = 4437(2) Å3, respectively. The axial Cr–O bond length for 1 and the axial Cr–N bond length for 2 are 2.239(3) and 2.140(5) Å, respectively. Laser irradiation of the toluene solution of [Cr(tpp)(Cl)(L)] causes the photodissociation of the axial ligand L, where L represents H2O or 3-cyanopyridine, to give the five-coordinate intermediate [Cr(tpp)(Cl)]. The rate constant of the axial ligand recombination reaction falls into a narrow range around 1 × 109 mol−1 kg s−1 at 25.0 °C for both reactions. The activation parameters indicate the very high reactivity of the five-coordinate intermediate. The diffusion-controlled process is regarded as a rate-determining step for the recombination.
  • Yasuki Yoshimura
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2305-2311
    Published: 1995
    Released: July 09, 2006
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    fac-Tris(aniono)cobalt(III) of D-alanine, D-valine, D-leucine, L- and D-prolines, and L- and D-serines was synthesized, and the separation of the diastereoisomers of these chelates was attempted. The solubilities of these isomers in water were determined over the temperature range of 5 to 55 °C. The thermodynamic parameters of solution at 25 °C, such as the free energy (ΔGs°), enthalpy (ΔHs°), and entropy (ΔSs°), were estimated from the temperature dependence of the solubilities. Also, the dissolution behavior of these chelate in water was considered in terms of these thermodynamic parameters. Plot of ΔHs° against TΔSs° gave separate correlation lines for the groups comprising less soluble chelates and more soluble chelates. An increase in the solubility within the respective groups was caused by an increase in TΔSs°. Both ΔHs° and TΔSs° for the chelates of less hydrophobic glycine and serine were larger than those for the chelates of more hydrophobic amino acids.
  • Kentaro Okuma, Komei Ikari, Masaaki Ono, Yasunari Sato, Seiji Kuge, Hi ...
    1995 Volume 68 Issue 8 Pages 2313-2317
    Published: 1995
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    Reactions of (dimethylamino)phenylsulfoxonium methylide with triphenylvinylphosphonium salts gave the corresponding cyclopropyltriphenylphosphonium salts (E-form) in high yields, when 1,8-diazabicyclo[5.4.0]undec-7-ene was used as a base. Reactions of cyclopropyltriphenylphosphonium salts with sodium hydride in the presence of tris[2-(2-methoxyethoxy)ethyl]amine afforded the corresponding ylides, which further reacted with aldehydes to give alkylidenecyclopropanes in high yields.
  • Habib Firouzabadi, Iraj Mohammadpoor-Baltork
    1995 Volume 68 Issue 8 Pages 2319-2325
    Published: 1995
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    The synthetic utility of sodium and silver bromates in the presence of Lewis acids as catalysts in organic solvents is described. They are efficient for the oxidation of alcohols, acyloins, and hydroquinones to their corresponding carbonyl compounds. The oxidation coupling of thiols performs well in the absence of the catalysts. Silver bromate is able to transform primary benzylic and saturated alcohols, aldehydes, and primary benzylic carbon–hydrogen bonds to their carboxylic acids efficiently. Secondary benzylic carbon–hydrogen bonds are oxidized to their carbonyl compounds with sodium and silver bromates.
  • Shigeo Niihata, Hideyuki Kuno, Takashi Ebata, Hajime Matsushita
    1995 Volume 68 Issue 8 Pages 2327-2329
    Published: 1995
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    2′,3′-Didehydro-2′,3′-dideoxy nucleosides were synthesized from 2′,2′-bis(phenylthio) nucleoside analogs via five-step reactions. The sulfonyl group of the intermediate was removed by a treatment with sodium amalgam.
  • Shinkiti Koto, Hisamitsu Haigoh, Sonoko Shichi, Motoko Hirooka, Teiko ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2331-2348
    Published: 1995
    Released: July 09, 2006
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    Glycogen-storage-disease-relating linear tetra-, hexa-, and octasaccharides of D-glucose having α(1→4) and α(1→6) linkages were synthesized using a stereoselective dehydrative glycosylation with a reagent mixture of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, N,N-dimethylacetamide, and triethylamine. A cross-condensation of a quasi-stoichiometric amount of a donor and an acceptor of an octasaccharide, followed by deprotection, afforded a glucohexadecasaccharide.
  • Takashi Matsumoto, Yoshio Takeda, Kimiko Soh, Mitsuo Sakamoto, Sachihi ...
    1995 Volume 68 Issue 8 Pages 2349-2353
    Published: 1995
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    Methyl 7-oxo-5,8,11,13-abietatetraen-18-oate was reduced with sodium borohydride in the presence of cerium(III) chloride heptahydrate to give the corresponding 7-hydroxy compound, which was rearranged into methyl 7-isopropyl-1,10-dimethyl-1,2,3,4-tetrahydroanthracene-1-carboxylate (14) possessing a rearranged linear abietane skeleton, by a treatment with boron trifluoride etherate. The reduction of 14 with lithium aluminum hydride afforded 7-isopropyl-1,10-dimethyl-1,2,3,4-tetrahydroanthracene-1-methanol (15). This was further converted into 7-isopropyl-1,1,10-trimethyl-1,2,3,4-tetrahydroanthracene. The mesylate of 15 was also rearranged into 2-isopropyl-5,9-dimethyl-7,8-dihydro-6H-cyclohepta[b]naphthalene, possessing a seven-membered A ring.
  • Kazuhiko Saigo, Makoto Sukegawa, Yasunari Maekawa, Masaki Hasegawa
    1995 Volume 68 Issue 8 Pages 2355-2362
    Published: 1995
    Released: July 09, 2006
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    Topochemical photopolymerization of 4-[2-(unsubstituted and methyl-substituted pyrazinyl)ethenyl]cinnamates and -thiocinnamates were carried out in the crystalline state. Upon photoirradiation, ethyl 4-[2-(unsubstituted and methyl-substituted pyrazinyl)ethenyl]cinnamates and S-ethyl 4-[2-(unsubstituted and methyl-substituted pyrazinyl)ethenyl]thiocinnamates gave α-hetero-type crystalline linear polymers, whereas methyl 4-[2-(methyl-substituted pyrazinyl)ethenyl]cinnamates afforded mixtures of β-type oligomers. The X-ray crystallographic analyses of the monomers revealed that the thioesters were more favorable monomers than the corresponding esters from the viewpoint of close packing in a crystal. The following factor(s) would play an important role in determining their molecular arrangements: 1) The close contact between the central 1,4-phenylene ring and the alkoxy oxygen of the ester group or the alkylthio sulfur of the thioester group, 2) the hydrogen bond between the interstacked pyrazinyl groups, and/or 3) the gearing of the alkyl group in the ester moiety with the methylpyrazinyl group.
  • Hiroyuki Higuchi, Taketoshi Nakayama, Haruki Koyama, Juro Ojima, Tatsu ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2363-2377
    Published: 1995
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    The two types of highly-ordered oligo(3-hexylthiophene)s in head-to-head orientation, a series of α,ω-disubstituted oligothiophenes and a series of bis(dicyanomethylene)oligothienoquinonoids, were synthesized. The properties of these compounds are discussed on the basis of the electronic spectra and cyclic voltammetry.
  • Hiroyuki Kusama, Koichi Narasaka
    1995 Volume 68 Issue 8 Pages 2379-2383
    Published: 1995
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    The intermolecular Friedel–Crafts acylation of aromatic compounds (such as toluene, m-xylene, and anisole) with various acid chlorides proceeds by using a catalytic amount of bromopentacarbonylrhenium(I) to afford aryl ketones. Intramolecular acylation is also catalyzed by the above-mentioned catalyst to give indanone and tetralone derivatives.
  • Masaharu Tsuji, Masato Aizawa, Hiroki Ujita, Yukio Nishimura
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2385-2392
    Published: 1995
    Released: July 09, 2006
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    The gas-phase ion-molecule reactions of CF3+ with nitrogen-containing benzene derivatives (C6H5Y : Y = NH2, NO2, and CN), pyridine, pyrrole, and acetonitrile have been studied at near-thermal energy using an ion-beam apparatus. The major product channels are charge transfer for aniline (71.7 ± 0.5%), O abstraction for nitrobenzene (91.7 ± 0.5%), electrophilic addition leading to initial adduct ions for benzonitrile (97.5 ± 0.8%), acetonitrile (100%), and pyridine (94.8 ± 0.4%), and electrophilic addition followed by HF elimination for pyrrole (80.0 ± 1.4%). The reaction mechanism is discussed based on product ion distributions and theoretical calculations of the energies of reaction pathways.
  • Toshihide Hatsui, Jin-Jun Wang, Hitoshi Takeshita
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2393-2399
    Published: 1995
    Released: July 09, 2006
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    A mild base-catalyzed retro-benzilic acid rearrangement of a proto-photocycloadduct, formed in highly stereoselective photoaddition of methyl 2,4-dioxopentanoate to 1,5-dimethyl-6-methylene-1-cyclohexene, afforded a spiro[4.5]decenedione derivative. Reductive elimination of the α-dicarbonyl function and C1-homologation furnished (±)-hinesol and (±)-agarospirol.
  • Eisuke Kaji, Frieder W. Lichtenthaler, Yumiko Osa, Keiko Takahashi, Sh ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2401-2408
    Published: 1995
    Released: July 09, 2006
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    An efficient chemical synthesis is described for the title trisaccharide repeating unit of the capsular polysaccharide of Streptococcus pneumoniae Type 19F. The key intermediate was a well-accessible indirect β-D-mannosaminyl donor, i.e. 2-(benzoyloxyimino)-2-deoxy-α-D-arabino-hexopyranosyl bromide, which underwent glycosidations with 20 : 1 β-selectivities; the benzoyloxyimino group was reduced with essential manno specificity. The ManNAc-β(1→4)-Glc disaccharide, thus obtained in suitably blocked form, was subsequently converted into 1-fluoride, with which a L-rhamnosyl acceptor was glycosylated by an α(1→2) linkage to yield the target trisaccharide in an altogether 6% overall yield for the 13 steps required from D-glucose.
  • Akikazu Kakehi, Suketaka Ito, Ken Matsubara
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2409-2415
    Published: 1995
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    Various ethyl 2-(3-cyanoallylidene)- or 2-[3-(ethoxycarbonyl)allylidene]-1,2-dihydropyridin-1-ylacetates were prepared from the reactions of 1-(1-ethoxycarbonylalkyl)-2-methylpyridinium halides with activated ethoxymethylidene compounds in the presence of a base. The treatment of these 2-allylidene-1,2-dihydropyridine derivatives with acetic acid at the reflux temperature gave directly the title compounds in low to moderate yields.
  • Noritaka Ohtani, Yukihiko Inoue, Noriyuki Shinoki, Katsuhiro Nakayama
    1995 Volume 68 Issue 8 Pages 2417-2423
    Published: 1995
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    Simple nucleophilic substitutions were done under liquid–liquid phase-transfer reaction conditions using water-insoluble alcohols as organic solvents. The reactions proceeded at considerable rates even in the absence of any catalysts, depending on the alcohol, inorganic salt, and the aqueous concentration of the salts. An addition of single- or double-chained onium salts enhanced the reaction rate almost linearly with the amount of the onium salts. The concentrations of inorgainc salts and water in the alcohol phase were analyzed and the relationship between these concentrations and the observed rate constant was discussed. An interfacial reaction mechanism explains the kinetics of this reaction system better than the conventional ion-pair mechanism assumed by most research using hydrocarbon solvents.
  • Shinya Morishita, Ken-ichi Suzuki
    1995 Volume 68 Issue 8 Pages 2425-2428
    Published: 1995
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    In the presence of riboflavin and ethylenediaminetetraacetic acid (EDTA), deposition of copper was observed upon irradiation. Selective deposition of copper onto irradiated parts of a riboflavin-adsorbed alumina substrate was accomplished in an electroless copper plating solution containing EDTA. Two lines per millimeter were written on the substrate. The peel adhesion strength of the plated copper layer was comparable to that of a copper layer plated by a conventional method.
  • Jun Miki, Minoru Asanuma, Yakudo Tachibana, Tsutomu Shikada
    1995 Volume 68 Issue 8 Pages 2429-2437
    Published: 1995
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    Nickel, iron, and cobalt oxides showed excellent catalytic activities for the vapor-phase oxidation of benzoic acid to phenol at the reaction temperature of 400 °C. The combination of these metal oxides, catalyst preparation by precipitation followed by calcination at 800 °C, and addition of Na2O to the catalyst about 1% by weight enhanced the conversion of benzoic acid and the selectivity to phenol.
    The structure of precipitation catalyst, Fe/Ni atomic ratio on the catalyst surface and formation of sodium benzoate on the catalyst surface play important roles for the optimization of catalyst activity. The novel catalyst systems could throw a new light on a one-step phenol synthesis from toluene. Appreciable one-pass phenol yield was obtained using a binary catalyst system consisting of V2O5–K2SO4–TiO2 and NiO–Fe2O3–Na2O, in which V2O5–K2SO4/TiO2 worked as a catalyst for toluene oxidation to benzoic acid and NiO–Fe2O3–Na2O functioned as a catalyst for benzoic acid to phenol.
  • Joji Yoshimura, Akira Tanaka, Junko N. Kondo, Kazunari Domen
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 8 Pages 2439-2445
    Published: 1995
    Released: July 09, 2006
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    The photocatalytic ability of CdS/K4Nb6O17 photocatalyst for H2 evolution by visible light irradiation was studied in connection with its structure. CdS/K4Nb6O17 was prepared by cation exchange reaction of K+ to Cd2+ ions in aqueous Cd(NO3)2 solution, followed by sulfurization in aqueous Na2S solution. The catalyst obtained by this procedure showed much higher H2 evolution activity in aqueous K2SO3 solution under visible light irradiation (λ > 420 nm) than a physical mixture of CdS and K4Nb6O17 powders. This result was interpreted as due to more intimate contact of CdS and K4Nb6O17 in CdS/K4Nb6O17 photocatalyst, which enabled the efficient transfer of excited electrons. The activity of the catalyst was greatly dependent on the sulfurization condition, with this optimum condition: at room temperature for one week. XRD, EXAFS, TEM, and UV-DRS showed that most CdS particles, ca. 10 nm in diameter, existed on the external surface of K4Nb6O17, while a small amount of CdS was inferred to be located at the interlayer space of K4Nb6O17 as ultra fine particles.
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