Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 70 , Issue 10
Showing 1-31 articles out of 31 articles from the selected issue
  • Masahiko Matsukata, Eiichi Kikuchi
    1997 Volume 70 Issue 10 Pages 2341-2356
    Published: 1997
    Released: June 15, 2006
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    This article is intended to describe recent progress in the synthesis of zeolitic membranes and their permeation properties. While hydrothermal synthesis has been widely employed for zeolitic-membrane synthesis, the development of a new technique for zeolite synthesis, vapor-phase transport (VPT), has enabled us to prepare pinhole-free, zeolite-porous support composite membranes. This article consists of three sections that describe: a survey of the hydrothermal synthesis of zeolitic membranes, our synthesis results and the formation mechanism of zeolitic membranes by the VPT method as well as some permeation results to show the prospects of zeolitic membranes.
  • Haruhiko Yokoyama, Kazuteru Shinozaki, Shin Hattori, Fumiyo Miyazaki
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2357-2367
    Published: 1997
    Released: June 15, 2006
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    X-Ray diffraction measurements have been made for aqueous solutions of sulfates or chlorides of [Ru(phen)3]2+, [Ni(phen)3]2+, [Ru(bpy)3]2+, [Ni(bpy)3]2+, [Rh(bpy)3]3+, and [Cr(bpy)3]3+ (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine). Radial distribution functions for the metal interactions were obtained by the isomorphous substitution between ruthenium(II) and nickel(II) complexes or between rhodium(III) and chromium(III) complexes. Metal–nitrogen and metal–carbon distances within the complex ions in solution were essentially in agreement with those in the crystals. Regarding the divalent metal complexes, about two water molecules seemed to exist at a distance of 3.5—3.6 Å (1 Å = 10−10 m) from the central metal atom and 10—11 water molecules existed in the region of 5.3 to 6.3 Å, probably in the vicinity of peripheral hollows along the C3 axis of the complex. Further, large broad peaks with high electron density were observed around 7.7 and 11.2 Å for the [Ru(bpy)3]2+ ion and around 8.0 and 11.5 Å for the [Ru(phen)3]2+ ion, almost independent of salt concentration and kinds of counter ions. These were attributed to the hydrophobic hydration shells having the hydrogen-bonded network structure. The hydration structure of the trivalent metal complexes was significantly different from that observed for the divalent ones: 14—15 water molecules existed in the range of 4.7 to 6.0 Å, a part of them presumably in the hollows along the C2 axes of the complex, and only a single broad peak was observed around 7.7 Å as the hydrophobic hydration shell. These results indicated that the hydrophobic hydration structure was reduced by the increase of the ionic charge, as predicted from a comparison of temperature coefficients of the Walden product obtained by the conductivity measurements of dilute solutions.
  • Mohamad M. Ayad
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2369-2373
    Published: 1997
    Released: June 15, 2006
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    The spectrophotometric properties of the charge-transfer (CT) complexes of benzo[b]thiophene with iodine at 24 °C in different solvents such as cychlohexane, carbon tetrachloride, chloroform, dichloromethane, and 1,2-dichloroethane are studied. In addition the spectrophotometric and thermodynamic properties of the CT complexes of benzo[b]thiophene with tetracyanoethylene, chloranil, 2,3-dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8,-tetracyanoquinodimethane are studied. The results show that the equilibrium and the thermodynamic parameters and the wavelengths of the maximum absorption bands (λmax) of the complexes vary markedly with the solvent. The ionization potential and the donor sites of benzo[b]thiophene are also determined and discussed.
  • Toshimasa Ishida, Yasuko In, Chiuru Hayashi, Reijiro Manabe, Akio Waka ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2375-2381
    Published: 1997
    Released: June 15, 2006
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    A copper(II) complex of the Schiff base condensation of pyridoxal 5-phosphate (PLP) with pyridoxamine 5-phosphate (PMP) was precipitated as an end product during a nonenzymatic copper(II)-mediated transamination reaction of L-amino acid (alanine, leucine, lysine, glutamic acid, or glutamine) via Schiff base formation with PLP at pH = 2.5. The complex was determined by an X-ray crystal structure analysis to consist of a dimer of Cu(II)·[PLP–PMP Schiff base]·7H2O, where a covalent bond is formed between the carbon atoms of neighboring Schiff base –C=N– fragments. The crystal consists of a racemate of the (R,R)- and (S,S)-configuration at the covalently bonded carbon atoms. By this bond formation and the phosphate O–Cu(II) coordination between neighboring dimers, complexes exist as a polymerized form in the crystal. The copper(II) ion forms a thermally stable square-pyramidal five-coordination with an azomethine nitrogen, two pyridine oxygens, a water oxygen, and a phosphate oxygen. Possible in vitro copper(II)-mediated formation of the complex from PLP and L-amino acid is considered.
  • Toshie Harazono, Tokuko Watanabe
    1997 Volume 70 Issue 10 Pages 2383-2388
    Published: 1997
    Released: June 15, 2006
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    The chemical shift, the range of chemical shift anisotropy, and the spin-lattice relaxation times (T1) in Y2O3, Y3Al5O12, and Y2O2S have been measured by solid state 89Y (nuclear spin 1/2)-MAS and -static NMR. The static NMR data and T1 are reported for the first time. The range of chemical shift anisotropy was 1500—2400 Hz. This range was influenced more by the nature of the atom bound to Y than by the coordination number or the crystallographic symmetry of Y. Very long T1 values were obtained for Y2O2S (6.61 h) and Y2O3 (3.92 h at 24d site and 3.81 h at 8b site). On the other hand, the T1 value (1.10 h) of Y3Al5O12 is much shorter compared with those of Y2O2S and Y2O3. The next-nearest neighboring atom of Y in Y3Al5O12 is identified as Al, which has the nuclear spin 5/2 of 100% natural abundance. The most likely origin of significantly shorter T1 of Y3Al5O12 is a dipole–dipole interaction between 89Y and 27Al.
  • Refat Abdel-Hamid, Mostafa K. Rabia, Hussein M. El-Sagher
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2389-2397
    Published: 1997
    Released: June 15, 2006
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    At hanging mercury-drop electrode (HMDE) Alizarin Red S (ARS) is electrochemically reduced in aqueous buffer solutions, giving rise to a prominent wave and a pre-wave. The prominent wave is diffusion-controlled and involves two electrons and two protons. The pre-wave is attributed to a strong reversible adsorption of the reduction product at the electrode. The reduction mechanism was proposed and discussed on the basis of the cyclic voltammetric and double potential-step chrono-amperometric & coulometric results. It was concluded that the reduction pathway is an ECEC mechanism in which the chemical reactions (C) are a dimerization of the formed radical anion and protonation of the dianion dimer, respectively. The rate-determining step is the protonation reaction. The adsorption process obeys a Langmuir isotherm with maximum surface excess of 1.4 × 10−10 mol cm−2 at a bulk concentration ≥4.6 × 10−5 mol dm−3, corresponding to 1.18 nm2/molecule. This indicates that ARS is horizontally oriented and resists reorientation upon increasing its bulk concentration.
  • Yasushi Umemura, Akihiko Yamagishi, Ken-ichi Tanaka
    1997 Volume 70 Issue 10 Pages 2399-2403
    Published: 1997
    Released: June 15, 2006
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    Multilayer films of alternately layered zirconium and hafnium phosphonates on silicon substrates were prepared and characterized by X-ray photoelectron spectroscopy. It is revealed that the multilayer film is built up layer-by-layer in the repeated order of a zirconium phosphonate layer and a hafnium phosphonate layer. The relative peak intensity of the Zr 3d line to the Hf 4d5/2 line in the photoelectron spectra of the film takes a lower value as the take-off angle between the surface normal and the detector (α) increases. The mean free path of a photoelectron with an energy of ca. 1000 eV was estimated to be 70—90 Å in the film by analyzing the α dependence of the relative peak intensities.
  • Yasumasa Tomita, Koji Yamada, Hiroshi Ohki, Tsutomu Okuda
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2405-2410
    Published: 1997
    Released: June 15, 2006
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    Cation diffusion in MGaBr4 (M = Li, Cu) was confirmed by measuring the temperature dependence of the 7Li and 63Cu NMR linewidths. The activation energies for the cation diffusion were determined to be 36 and 44 kJ mol−1 for LiGaBr4 and CuGaBr4, respectively. The activation energy for the reorientation of the GaBr4 anion in CuGaBr4 was evaluated to be 62 kJ mol−1 from 71Ga NMR. The cation diffusion was also confirmed for MGaBr4 (M = Cu, Ag) by observing a modulation effect on the 81Br NQR T1. As expected from the modulation effect of NQR, the ionic conductivity of AgGaBr4 was one order higher than that of CuGaBr4.
  • Tomohiko Ohwada, Hirotaka Kagawa, Hiroshi Ichikawa
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2411-2415
    Published: 1997
    Released: June 15, 2006
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    The constrained HF method was applied to the estimation of conjugation of Y-shaped molecules. This method does not include the effect of the geometrical change, and gives a direct measurement of π-conjugation energy. We conclude that the magnitude of conjugation in a trimethylen–methane dianion is around that of a hexadienediide dianion, far less than that of a neutral cyclic aromatic compound (typically that of benzene). This is consistent with the previous conclusions obtained with the different energetic criteria. The physical meaning of Y-conjugation was interpreted in terms of relaxation of the kinetic-energy pressure of the π electrons.
  • Tsuneo Koura, Yuji Ohashi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2417-2423
    Published: 1997
    Released: June 15, 2006
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    The crystal structure of (S)-s-butylamine(2-cyanoethyl)cobaloxime was determined by X-ray analysis; the crystal is monoclinic, and the space group is C2, Z = 4 with a = 15.656(2), b = 11.699(2), c = 11.553(1) Å, β = 96.979(9)° and V = 2100.5(5) Å3. The structure was refined by a full-matrix least-squares method to the final R value of 0.052 for 1678 observed reflections. The 2-cyanoethyl group takes a perpendicular conformation to the cobaloxime plane and has disordered conformations (A, B, and C) around the Co–C bond. The occupancy factors of A, B, and C are 0.48, 0.34, and 0.18, respectively. The crystalline sample was irradiated with a xenon lamp. The (R)-1-cyanoethyl group is preferentially produced from the (S)-s-butylamine complex. The conversion rates, which were determined by HPLC analysis using the chiral stationary phase, were obtained to be 1.17 × 10−5 and 0.59 × 10−5 s−1 for the (R)- and (S)-1-cyanoethyl groups, respectively. The diastereomeric excess is 27%. Such asymmetric induction is well explained by the shape of the reaction cavity for the 2-cyanoethyl group, and is also in good agreement with a packing-energy calculation by molecular mechanics.
  • Neelam Yugandhar Sreedhar, Polu Rajendra Kumar Reddy, Gopi Reddy Venka ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2425-2427
    Published: 1997
    Released: June 15, 2006
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    The electrochemical behavior of the fungicides folfet, phosmet, and dialifos was studied using differential pulse polarography in unversal buffers of pH 2.0 to 6.0. The cathodic peak observed for folfet, phosmet, and dialifos is attributed to the reduction of the carbonyl group, and was shown to be pH-dependent. Differential pulse polarography was used to estimate folfet, phosmet, and dialifos in agricultural formulations, grains and soil samples. Both standard addition and calibration methods were used for the analytical measurements. The lower detection limits were found to be 1.9 × 10−9, 1.72 × 10−9, and 2.12 × 10−1 M, respectively.
  • Chunmin Li, Nobuko Kanehisa, Yoshie Miyagi, Yasuo Nakao, Satoshi Takam ...
    1997 Volume 70 Issue 10 Pages 2429-2436
    Published: 1997
    Released: June 15, 2006
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    In this paper we report our recent research on the dinuclear copper(II) and nickel(II) complexes 110 (Chart 1) containing Schiff bases, derived from acetylacetone, benzoylacetone, or trifluoroacetylacetone, and 1,3-diaminopropane-2-ol. These complexes are bridged by an alkoxide and a pyridazine (pyd) or phthalazine (phta). The magnetic susceptibilities, visible absorption spectra, conductivities, and redox properties of the complexes were investigated and the molecular structures of 2, 4, and 5 are described. The Cu–O–Cu angles found in these complexes indicate a role of the alkoxo-bridge as one of the principal antiferromagnetic exchange pathways. At the same time, the coplanarity of two coordination planes of copper(II) ions is also shown to relate to the exchange process.
  • Yuri Mizuno, Aya Yokote, Masayasu Iida
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2437-2442
    Published: 1997
    Released: June 15, 2006
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    Interactions of tripositive cobalt(III) complex ions, such as Δ(lel3)-[Co(chxn)3]3+ (chxn = (R,R)-1,2-cyclohexanediamine), [Co(oct-en)(2,3,2-tet)]3+ (oct-en = N-octylethylenediamine, 2,3,2-tet = 3,7-diazanonane-1,9-diamine), [Co(sep)3]3+ (sep = sepulchrate = 1,3,6,8,10,13,16,19-octaazabicyclo[6.6.6]eicosane), and [Co(tn)3]3+ (tn = trimethylenediamine), in various solvents were studied using 59Co chemical shifts together with the electronic absorption spectra. The results are discussed in comparison with those of [Co(en)3]3+, whose 59Co chemical shift in various solvents had been previously reported to be fairly proportional to the donor numbers. There was a trend that the 59Co chemical shift changes greatly if the acidic NH-hydrogen atoms of the ligands are favorable to form hydrogen bonding with the solvents. The magnitudes of the chemical-shift changes for [Co(tn)3]3+ were significantly smaller than those for the en and chxn complexes. This difference can be attributed to the more conformationally labile structure of the tn complex in solution.
  • Katsutoshi Inoue, Keisuke Ohto, Kazuharu Yoshizuka, Tomoo Yamaguchi, T ...
    1997 Volume 70 Issue 10 Pages 2443-2447
    Published: 1997
    Released: June 15, 2006
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    Two kinds of complexane-type of chitosan chemically modified with EDTA and DTPA were synthesized and examined concerning the adsorption behavior for iron(III), copper(II), nickel(II), zinc(II), aluminium(III), and lead(II) from a dilute hydrochloric acid solution. Both of these adsorbents were found to adsorb lead(II) at low pH in a similar highly selective manner over zinc regardless of the kind of acid, whether it be hydrochloric acid or nitric acid, and to have a much stronger adsorption power compared with a commercial phosphonamidic acid-type chelating resin. The maximum adsorption capacities of lead were 1.8 and 1.5 mol/kg-dry gel for DTPA- and EDTA-chitosan. The breakthrough followed by elution tests demonstrated that it is achievable to concentrate a small amount of lead(II) which has been very selectively separated from a large excess of zinc by using an adsorption column packed with these adsorbents.
  • Toshio Nakamura, Hideyuki Mongi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2449-2453
    Published: 1997
    Released: June 15, 2006
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    The response behaviors of an ionophore-conjugated polymer-based ion sensor, which consists of a polyacrylamide (PAA) coupled to benzo-15-crown-5 (B15C5), for Na+ and Ca2+ in acetonitrile (AN) and N-methylpyrrolidinone (NMP) were studied. The PAA–B15C5 electrode showed a Nerstian response to Na+ in AN and Ca2+ in AN and NMP. The electrode was then applied to investigate the complexation of Na+ in AN with such other solvent molecules (D) as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO); the successive complex formation constants and Gibbs energies of transfer of Na+ in AN to DMF or DMSO and AN to AN–D mixtures were obtained. Reasonable responses of the electrode to an activity change of Na+ due to the solvation of the basic solvent molecules could be certified. The complex formation constant of Ca2+ in AN with such D as DMF, NMP, N,N-dimethylacetamide (DMA), DMSO and hexamethylphosphoric triamide could be obtained by the electrode. The association constants of Ca2+ with CF3SO3 in AN, propylene carbonate, DMF, and DMSO were determined conductometrically and the constant in AN (K1AN = 1.02 × 104 dm3 mol−1) was used for correcting the variation of calcium ion-activity due to a concentration change of Ca(CF3SO3)2 in AN.
  • Isao Kawafune, Hatsue Tamura, Gen-estu Matsubayashi
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2455-2460
    Published: 1997
    Released: June 15, 2006
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    The crystal structure of the title compound as the cesium salt of the vanadium-trisubstituted dodecatungstophosphate anion was determined by a single X-ray analysis. The anion is a geometrical β-isomer and an A-type positional isomer; three V atoms are not in disorder with W atoms, being linked to one another through the corner-sharing oxygen atom. The V–V distances are substantially shortened in comparison with the corresponding W–W ones of the β-tungstosilicate analogs, which is attributable to a difference in ion radii of V5+ (0.68 Å) and W6+ (0.74 Å). A non-bonded contact between a Cs atom and one of the bridging oxygen atoms in the V–O–V bonds is apparently short compared with the other contacts between the Cs atoms and oxygen atoms of the polyanion. Taking into consideration that this Cs atom is in disorder with a proton, this bridging oxygen atom is considered to be protonated. A bond-valence calculation for the bridging oxygen atoms in the polyanion also suggests protonation of this bridging oxygen atom.
  • Naohide Matsumoto, Masaaki Mimura, Yukinari Sunatsuki, Shingo Eguchi, ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2461-2472
    Published: 1997
    Released: June 15, 2006
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    Four copper(II) complexes with unsymmetrical quadridentate ligands involving an imidazole moiety, [CuHLn]ClO4 (14; n = 1—4), have been prepared and characterized, where HL1 = N-salicylidene-N′-(2-methylimidazol-4-ylmethylidene)-1,3-propanediamine, HL2 = N-salicylidene-N′-(2-phenylimidazol-4-ylmethylidene)-1,3-propanediamine, HL3 = N-acetylacetonylidene-N′-(2-methylimidazol-4-ylmethylidene)ethylenediamine, HL4 = N-acetylacetonylidene-N′-(2-phenylimidazol-4-ylmethylidene)ethylenediamine, respectively. The corresponding deprotonated complexes 1′—4′ were obtained when 14 were treated under an alkaline condition. Deprotonation of the imidazole moiety of the copper(II) complex motivates a self-assembly process which is formed by an axial coordination of the imidazolate nitrogen atom of a molecular unit to the copper(II) ion of another unit. 1′—3′ assumes a self-assembled imidazolate-bridged infinite-chain structure {Cu(II)–Im}n in the solid state, while the polymeric species dissociates to monomeric species in the solution state. 4′ consists of a discrete deprotonated monomeric species, even in the solid state. The physical measurements, including reflectance and absorption spectra, cryomagnetic measurements, and single-crystal X-ray analyses, revealed that the self-assembly behavior for the series of copper(II) complexes depends both on the steric effect of the substituent of 2-substituted-4-formylimidazole moiety and the ligand field strength of the equatorial quadridentate ligand.
  • Toshiyuki Osakai, Kohji Maeda, Kuniyoshi Ebina, Hiroko Hayamizu, Motoh ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2473-2481
    Published: 1997
    Released: June 15, 2006
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    The first and second redox potentials ( and ) of Keggin-type heteropolytungstate anions (α-[PW12O40]3− and α-[SiW12O40]4−) have been determined in various solvents by means of cyclic voltammetry. The difference () between and , being theoretically associated with the solvation energies of the polyanions, does not correlate with the permittivity of the solvent, in conflict with an expectation based on the Born-type electrostatic solvation model. In contrast, has been found to show some definite correlations with such empirical solvent parameters as acceptor numbers. This shows that the short-range interactions (i.e., donor–acceptor effects or hydrogen bonds) between the heteropolyanion and its primary solvents play the most significant role in the solvation of the heteropolyanions. We have thus proposed a new analytical equation for evaluating the short-range ion–solvent interaction energy.
  • Shuji Oishi, Isao Sugiura
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2483-2487
    Published: 1997
    Released: June 15, 2006
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    Well-formed crystals of chlorapatite [Ca5Cl(PO4)3] were first grown from a sodium chloride flux. The solubility of Ca5Cl(PO4)3 in NaCl increased with increasing temperature. At 1100 °C, Ca5Cl(PO4)3 had a solubility of about 0.15 mol%. The crystal growth of Ca5Cl(PO4)3 was conducted by heating a mixture of solute and flux at 1100 °C for 10 h, followed by cooling to 500 °C at a rate of 5 °C h−1. Colorless and transparent crystals having lengths up to 4.0 mm and widths of 1.2 mm were grown from high-temperature solutions containing small amounts of solute (0.05—0.5 mol%). The obtained crystals were divided into two distinct morphological types: prisms and needles. The most suitable solute contents for the growth of prismatic and needle crystals were 0.15 and 0.1 mol%, respectively. The crystal forms were also dependent on the solute content. The prismatic crystals were bounded by the {} and {} faces. The needle crystals elongated in the <0001> directions. Calcium, chlorine, phosphorus, and oxygen were almost homogeneously distributed in the crystals.
  • Hajime Katano, Mitsugi Senda
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2489-2493
    Published: 1997
    Released: June 15, 2006
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    The half-wave potentials of the voltammetric waves of facilitated transfer of Pb2+ ion by 1,4,7,10,13,16-hexathiacyclooctadecane across the nitrobenzene/water interface have been measured as a function of the concentration of free CH3COO ion in aqueous phase. Using the equation of reversible half-wave ion-transfer potential, the formal formation constants of 1 : 1, 1 : 2, and 1 : 3 Pb2+–CH3COO complexes in the aqueous medium have been determined to be 102.3 M−1, 103.0 M−2, and 104.0 M−3, respectively. A polynomial regression method for the determination of the formation constants from voltammetric data is presented. Ion-transfer voltammetry at the liquid/liquid interface can be applied advantageously to the determination of consecutive formation constants of metal complexes with a ligand in aqueous media as well as those with an ionophore in organic media.
  • Masahiro Mikuriya, Yasushi Hatano, Eiji Asato
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2495-2507
    Published: 1997
    Released: June 15, 2006
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    Manganese(II) complexes with N,N′-bis(2-pyridylmethylene)-1,3-diaminopropan-2-ol (HL1) or N,N′-bis(2-pyridylmethylene)-1,3-propanediamine (L2), [Mn(HL1)(NO3)2] (1) and [Mn(HL1)(NCS)2] (2), [Mn(HL1)(phen)](ClO4)2 (3), [Mn2(L1)(CH3COO)(phen)2](ClO4)2 (4), [Mn(L2)(NO3)2] (5), [Mn(L2)(bpy)(CH3OH)](ClO4)2 (6), [Mn(L2)(NCS)2] (7), [Mn(L2)(phen)](ClO4)2 (8), have been synthesized and characterized by measurements of the infrared, electronic, and ESR spectra, and magnetic susceptibilities. The molecular structures of these complexes were determined by the single-crystal X-ray structure analysis. The complexes 1·C2H5OH and 5 have an eight-coordinated manganese atom with a square antiprism geometry. The complex 6 is seven-coordinated in a monocapped trigonal prism. The manganese atoms of 2, 7, and 8 are six-coordinated in a trigonal prism environment. The coordination environment of 3 is disordered between the seven- and six-coordinate geometries. The complex 4·H2O is a dinuclear molecule comprising two octahedral Mn(II) atoms.
  • Amit Basak, Gautam Bhattacharya, Sunanda K. Palit
    1997 Volume 70 Issue 10 Pages 2509-2513
    Published: 1997
    Released: June 15, 2006
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    Pig-liver esterase, which catalyzed the hydrolysis of substrates containing both saturated and α,β-unsaturated/cyclopropanecarboxylic esters (methyl and ethyl), was studied. An exclusive hydrolysis of the saturated esters was observed. Kinetic experiments revealed that the presence of deactivated carbonyl in the unsaturated/cyclopropanecarboxylic esters and their weaker bindings are both responsible for the observed specificity. The relative binding abilities of the substrates have been explained in light of Jones active-site model. The regioselectivity has been exploited in the synthesis of intermediates for the thromboxane synthetase inhibitor.
  • Naoaki Fukada, Takashi Tanaka, Tetsuo Fukuya, Yasuyuki Takeda
    1997 Volume 70 Issue 10 Pages 2515-2518
    Published: 1997
    Released: June 15, 2006
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    The reaction of dipotassium bis(dithiocarbonate)s from diethylene, triethylene, and tetraethylene glycols with dibromoalkanes or ethereal oxygen-containing diiodides under high-dilution conditions gave 1 : 1 reaction products, 14—25-membered macrocyclic bis(dithiocarbonic ester)s. From dimethyl esters of the bis(dithiocarbonic acid)s and diaminoalkanes or ethereal oxygen-containing diamines, macrocyclic bis(thiocarbamate)s were obtained.
  • Osamu Yamazaki, Hideo Togo, Genki Nogami, Masataka Yokoyama
    1997 Volume 70 Issue 10 Pages 2519-2523
    Published: 1997
    Released: June 15, 2006
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    The development of novel water-soluble organosilane compounds and their application to radical reactions in water medium have been studied. A series of novel organosilane compounds having hydrophilic groups, such as an ether group and a hydroxy group in the side chain to bear hydrophilicity, were synthesized by the reaction of trichlorosilane or tetrachlorosilane and Grignard reagents. The reactivities of these organosilane compounds were studied in the radical reduction of 2-bromoethyl phenyl ether in ethanol in the presence of triethylborane under aerobic conditions. The results showed that diarylsilane was the most effective among them. The radical reduction of alkyl and aryl halides with diarylsilane was applied to a reaction in aqueous media, which gave the corresponding reduction product in good yields. Thus, the present organosilanes are very useful for the reduction of water-soluble substrates, such as halo sugars in water.
  • Noriyoshi Arai, Koichi Narasaka
    1997 Volume 70 Issue 10 Pages 2525-2534
    Published: 1997
    Released: June 15, 2006
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    1-Nitroalkyl radicals are generated by oxidation of potassium salt of 1-aci-nitroalkanes with ammonium hexanitratocerate(IV). When the oxidation is carried out in the presence of electron-rich olefins, such as silyl enol ethers, intermolecular addition of the radicals onto the olefins proceeds to afford β-nitro ketones, which are further converted to α,β-unsaturated ketones in high yield. Stereoselective construction of fused ring systems is achieved by intramolecular addition of 1-nitroalkyl radicals.
  • Takeshi Sugai, Hanako Okazaki, Atsuhito Kuboki, Hiromichi Ohta
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2535-2540
    Published: 1997
    Released: June 15, 2006
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    N-Acetyl-D-allosamine and its derivatives were synthesized from tri-O-acetyl-D-glucal based on lipase-catalyzed selective protection of primary alcohols, [3,3] sigmatropic rearrangement of allylic trichloroacetimidates, and stereoselective ruthenium-catalyzed dihydroxylation. In the course of this study, it was revealed that the Pseudomonas lipase-catalyzed acetylation occurred in a high yield (> 90%) exclusively at the primary alcohols of three Ferrier rearrangement products derived from tri-O-acetyl-D-glucal.
  • Haruki Niwa, Akio Kuroda, Tomoyo Sakata, Kiyoyuki Yamada
    1997 Volume 70 Issue 10 Pages 2541-2543
    Published: 1997
    Released: June 15, 2006
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    Necine bases of pyrrolizidine alkaloids, turneforcidine, hastanecine, and platynecine are synthesized from ethyl 1-hydroxy-2,3,5,6-tetrahydro-1H-pyrrolizine-7-carboxylate in racemic form.
  • Tadashi Eguchi, Hiroki Kano, Kenji Arakawa, Katsumi Kakinuma
    1997 Volume 70 Issue 10 Pages 2545-2554
    Published: 1997
    Released: June 15, 2006
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    Archaeal 72-membered macrocyclic tetraether model compounds (5 and 6) were synthesized by intramolecular dicarbonyl coupling with the aid of low-valent titanium, which is known as McMurry coupling. This synthetic methodology is the first practical way to obtain the two regioisomeric structures in quantity and appears to be applicable to the natural 72-membered tetraether lipids (3 and 4). Also described is the synthesis of the corresponding acyclic tetraether model counterparts (7 and 8) in reference to the cyclic lipids.
  • Keiichi Akimoto, Yoshiaki Sugihara, Juzo Nakayama
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 10 Pages 2555-2559
    Published: 1997
    Released: June 15, 2006
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    Methylation of propyl 3,3-dipiperidinodithioacrylate with iodomethane afforded a 93 : 7 mixture of (E)- and (Z)-3-methylthio-3-propylthio-1,1-dipiperidino-2-propenylium iodides nearly quantitatively, while propylation of methyl 3,3-dipiperidinodithioacrylate with 1-iodopropane produced a 6 : 94 mixture of the above isomers. Study of these iodides led to the conclusions that (a) free rotation about the C2–C3 bond is frozen for these carbenium ions, thus allowing the clearly distinguishable E- and Z-isomers to exist and (b) the alkylation takes place in such a manner that the newly formed S-alkyl group and the carbenium carbon atom become cis to each other. Such stereoselectivity was general for methylation of a series of alkyl 3,3-dipiperidinodithioacrylates and was explained by examining the preferred conformation of the starting dithioacrylates with NMR and X-ray diffraction analyses.
  • Satoshi Sakaguchi, Daisuke Kikuchi, Yasutaka Ishii
    1997 Volume 70 Issue 10 Pages 2561-2566
    Published: 1997
    Released: June 15, 2006
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    NaBrO3 combined with NaHSO3 was found to be an excellent oxidizing reagent of alcohols, diols, and ethers under mild conditions. A variety of aliphatic and cyclic diols were selectively oxidized with satisfactory yields to the corresponding hydroxy ketones and/or diketones, which are difficult to selectively prepare due to a concomitant formation of cleaved products. For example, 2-hydroxycyclohexanone and 1,2-cyclohexanedione were selectively formed by allowing 1,2-cyclohexanediol to react with NaBrO3/NaHSO3 reagent in a selected solvent. On the other hand, an alkyl ether, such as dioctyl ether, reacted with NaBrO3/NaHSO3 in water at room temperature to give octyl octanoate in 82% yield. The same oxidation at higher temperature (60 °C) produced the α-brominated ester, octyl 2-bromooctanoate, which is considered to be formed through an alkenyl alkyl ether as the intermediate. The treatment of 1-ethoxy-1-heptene with NaBrO3/NaHSO3 afforded ethyl 2-bromoheptanoate and 2-bromoheptanoic acid as the major products.
  • Zheng Bao Wang, Tooru Mizusaki, Tsuneji Sano, Yusuke Kawakami
    1997 Volume 70 Issue 10 Pages 2567-2570
    Published: 1997
    Released: June 15, 2006
    JOURNALS RESTRICTED ACCESS
    The catalytic performance of various protonated zeolites for the Baeyer–Villiger (BV) oxidation of cyclopentanone to δ-valerolactone with aqueous H2O2 as an oxidant was investigated. It was found that highly siliceous HZSM-5 zeolites are active for the oxidation reaction, and that the oxidation reaction is promoted by the Brønsted acid sites in the intracrystallines of zeolites, not on the external surface. The influences of the reaction variables (solvent, temperature, and time) and the crystal size of zeolite on the conversion of cyclopentanone and the yield of δ-valerolactone were also studied.
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