bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Polarographic Behavior of Tl(I) and Na(I) Ions and Bis(o-phenylenediamine)nickel(II) in N,N-Dimethylformamide- Dimethyl Sulfoxide Mixtures
Authors: Sawada Shigeo 
Published: July 2006

Abstract
The polarographic behavior of Tl(I) and Na(I) ions and the bis(o-phenylenediamine)nickel(II) [Ni(opd)2] complex were studied using N,N-dimethylformamide (DMF)–dimethyl sulfoxide (DMSO) mixed solvents of various compositions. The diffusion currents of the Tl(I) and Na(I) ions and [Ni(opd)2] complex decreased linearly with an increase in the concentration of the supporting electrolyte in DMF–DMSO solvent mixtures. The ratio of the slope to the intercept is related to the D coefficient in the revised Jones-Dole equation of viscosity. Ion-solvent interaction was considered from the Stokes radius, calculated from the diffusion current at an infinite dilution of the supporting electrolyte. The half-wave potentials of both the Tl(I) ion and the [Ni(opd)2] complex shifted to a negative direction with an increase in the concentration of the supporting electrolyte. Although the half-wave potential of the [Ni(opd)2] complex shifted to a slightly positive potential, that of the Tl(I) ion shifted to a negative potential with an increase in the content of DMSO.
Lumiflavin-sensitized Photooxygenation Accelerated by Adenine. III. Flash Photolytic Studies
Authors: Yoshimura Akio , Kato Shunji 
Published: July 2006

Abstract
Flash photolytic studies have been made of aqueous systems of lumiflavin–adenine–tryptophan, where the accelerating effect of adenine is observed on the lumiflavin-sensitized photooxygenation of tryptophan. The electron transfer occurs first from adenine to the triplet state of lumiflavin. When a little tryptophan is present in the aerated solutions, the tryptophan is oxidized by the successive electron-transfer reactions and the tryptophan decomposes instead of adenine. The rate parameter for each process has been determined.
Synthesis of Naphthalenoferrocenophanes
Authors: Kasahara Akira , Izumi Taeko , Shimizu Iwao , Oikawa Tadashi , Umezawa Hiroshi , Murakami Manabu , Watanabe Osamu 
Published: July 2006

Abstract
Several naphthalenoferrocenophanes, in which the two cyclopentadienyl rings are linked by two naphthalene rings, were synthesized via intramolecular reductive coupling of the corresponding formyl compounds with a low valent titanium reagent. Their structures are deduced from IR, NMR, and UV spectra. Transannular π-electronic interaction between the two naphthalene rings is discussed on the basis of electronic spectra.
The C-13 NMR Spectra of Thiophenes. II. 2-Substituted Thiophenes
Authors: Fujieda Kunimi , Takahashi Kensuke , Sone Tyo 
Published: July 2006

Abstract
Carbon-13 NMR data of 14 2-substituted thiophenes were obtained in CDCl3. The correlation between the carbon chemical shifts and the Hammet constants was poor. The charge densities of typical compounds were calculated by the CNDO/2 method and they discussed in connection with the observed C-13 chemical shifts.
Influences of Supporting Silica Gel on the Catalytic Activity of B-18 Crown Ether–KCl Complex for the Selective Dehydrochlorination of 1,1,2-Trichloroethane
Authors: Fujitsu Hiroshi , Takagi Takeshi , Mochida Isao 
Published: July 2006

Abstract
Catalytic dehydrochlorination of 1,1,2-trichloroethane into 1,1-dichloroethylene proceeded selectively around 200 °C over dibenzo-18-crown-6-KCl complex supported on silica gels. The reaction rate depended very much on the kinds of silica gel and impregnation levels of the complex, suggesting some roles of surface hydroxyl groups in this catalysis.
Biaryl Formation in the Copper(I) Mediated Arylation of Stable Enolate Anions with o-Halogenonitrobenzenes
Authors: Thiruvikraman Singanallore V , Suzuki Hitomi 
Published: July 2006

Abstract
o-Bromo- and o-iodonitrobenzenes react with stable enolate anions in hot DMF in the presence of copper(I) iodide, to afford not the expected arylation products but the coupling products, 2,2′-dinitrobiphenyls.
The Synthesis of Internal Conjugated (E)-Enynyldialkylboranes and Their Applications to the Syntheses of Conjugated Alkynones, Conjugated (E)-Enynes, and Conjugated Enynes Bearing an Unsaturated Group on the Double Bond
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira 
Published: July 2006

Abstract
Internal conjugated (E)-enynyldialkylboranes were synthesized by successive reactions of 1-iodo-1-alkynes with dialkylboranes and 1-alkynyllithiums in 31–79% yields. (E)-Enynyldialkylboranes, thus obtained, gave regio- and/or stereospecifically defined corresponding conjugated alkynones by alkaline hydrogen peroxide oxidation, conjugated (E)-enynes by protonolysis with acetic acid, and conjugated enynes bearing an unsaturated group on the internal alkenyl carbon atom by bis(acetylacetonato)copper-catalyzed cross-coupling reaction with allyl bromide or 1-bromo-1-hexyne respectively.
Dechlorination of Polychlorobenzenes over Triiron Tetraoxide in the Presence of Hydrogen Donating Solvents
Authors: Hao Cui Xiang , Nakada Masahiro , Yamaguchi Tatsuaki , Fukushi Sachio , Hirota Minoru 
Published: July 2006

Abstract
Dechlorination of polychlorobenzenes over Fe3O4 was investigated by a pulse micro-reactor technique. Dechlorinations of various polychlorobenzenes in hexane and cyclohexane were carried out in the gas phase at the temperatures ranging from 498 to 623 K. In the presence of such hydrogen donating solvents, dechlorination was shown to proceed almost exclusively. The relative rates of dechlorination were measured by gas chromatography. It was found that the solvents used to dissolve polychlorobenzenes plays a role of a hydrogen donor in this reaction. The different rates among unequivalent chlorine atoms in a molecule were interpreted by the effect of steric acceleration caused by the neighboring chlorine atom(s). The reaction will probably proceed via hydrogenolytic cleavage of C–Cl bonds.
The Ability of an α-Aminoisobutyric Acid Residue to Promote Helical Folding in Oligopeptides
Authors: Narita Mitsuaki , Ishikawa Kazunori , Sugasawa Hiroki , Doi Masamitsu 
Published: July 2006

Abstract
In order to investigate the ability of an Aib residue to promote helical folding in oligopeptides, oligo(Leu)s containing an Aib residue were prepared by stepwise elongation and fragment condensation methods. The peptides prepared were the following: Boc–Aib–Leun–OBzl (n=3–6 and 9), Boc–Leun–Aib–OBzl (n=3–6 and 9), Boc–Leu3–Aib–Leu3–OBzl, Boc–Leu4–Aib–Leu4–OBzl, Boc–Leu8–Aib–Leu4–OBzl, Boc–Leu4–Aib–Leu8–OBzl, and Boc–Leu8–Aib–Leu8–OBzl. The IR absorption conformational analyses of Boc–Aib–Leun–OBzl (n=3–6) in dichloromethane have shown the occurrence of incipient helical structures (α- or 310-helixes) formed by one, two, three, and so forth i→i–4 or i→i–3 hydrogen-bonding patterns. All the peptides except Boc–Aib–Leu9–OBzl and Boc–Leun–Aib–OBzl (n=6 and 9) have also shown helical structures (α- or 310-helixes), indicating the great ability of an Aib residue to promote helical folding in peptides. This is in remarkable contrast with the fact that homologous oligo(Leu) counterparts have β-sheet structures. The solubility properties of the peptides were in good agreement with those speculated from their conformations. The initiation and stabilization mechanism of helical folding in peptides has been illustrated schematically and attributed to the restriction of the values of the backbone dihedral angles φ and ψ of an Aib residue due to steric hindrance, followed by the restriction of the values of φ and ψ of other amino acid residues due to hydrogen bonds initiated by the Aib residue. The great ability of an Aib residue to promote helical folding in peptides also suggests that the restriction of the values of the backbone dihedral angles φ and ψ (right-handed α-helix: φ=−57°, ψ=−47°) of an amino acid residue in peptide chains is one of important initiation mechanisms of α-helical folding in natural proteins. The implication of the new findings for the study of proteins containing Aib residues is presented on the basis of the stabilizing efficacy of Aib residues on helical regions of proteins.
Complex Formation and Solvation of [CuCln](2–n)+ in Acetonitrile and in N,N-Dimethylformamide
Authors: Ishiguro Shin-ichi , Jeliazkova Bojana G , Ohtaki Hitoshi 
Published: July 2006

Abstract
Complex formation equilibria between copper(II) and chloride ions have been studied by calorimetry and spectrophotometry in acetonitrile(AN) containing 0.1 mol dm−3 (C2H5)4NClO4 as a constant ionic medium at 25 °C. Both calorimetric and spectrophotometric titration curves could be well explained in terms of formation of a series of four mononuclear complexes, [CuCln](2−n)+ (n=1–4), and formation constants, enthalpies and entropies of formation of the complexes were determined. Stepwise enthalpies ΔHn° (n=1–4) were all negative, the ΔH4° value being especially largely negative. On the other hand, the stepwise entropy ΔSn° was largely positive for n=1–3, but largely negative for n=4. The result suggested that solvation of the [CuCl3]− complex was extremely weak in AN and that release of solvent molecules from [CuCl3]− was not so significant that the enthalpy and entropy of formation of [CuCl4]2− were mainly attributable to those of desolvation of Cl− followed by a bond formation between the [CuCl3]− complex and the chloride ion. The [CuCl4]2− complex might have no solvent molecules in the primary coordination sphere of the metal ion within the complex in AN. Enthalpies of solution of anhydrous CuCl2 crystals were measured in AN and N,N-dimethylformamide(DMF) in order to evaluate enthalpies of transfer ΔHt° of Cu2+ from water to the aprotic solvents. The ΔHt° values well correlated with Gutmann’s donor number of the solvents. The enthalpies of transfer ΔHt° of [CuCln](2−n)+ (n=0–4) from AN to DMF were evaluated, and the enthalpy values monotonously increased with n. The ΔHt°(CuCl42−) value was only slightly positive as well as ΔHt°(Cl−), and the result also suggested that the metal ion within the complex was not primarily solvated with solvent molecules in both AN and DMF. Electronic spectra of individual copper(II) chloride complexes were determined in AN.
Preparation and CD Spectra of Cobalt(III) Complexes with S-(Carboxymethyl)-l-cysteinate and Its Analogues
Authors: Okamoto Ken-ichi , Suzuki Masutaro , Einaga Hisahiko , Hidaka Jinsai 
Published: July 2006

Abstract
Four cobalt(III) complexes of the [Co(l-quadridentate-N,S,O2)(en)]+ type were prepared; where l-quadridentate-N,S,O2 denotes S-(carboxymethyl)-l-cysteinate(l-cmc), S-(2-carboxyethyl)-l-cysteinate(l-cec), S-(carboxymethyl)-l-homocysteinate(l-cmhc), or S-(2-carboxyethyl)-l-homocysteinate(l-cehc). Each complex was chromatographically separated into the quasi-enantiomeric isomers; Λl-trans(O)-S(S) and Δl-cis(O)-R(S) for the l-cmc, l-cmhc, and l-cehc complexes, and Λl-trans(O)-R(S) and Δl-cis(O)-S(S) for the l-cec one. These isomers were characterized from their absorption and 13C NMR spectra. The sterically strained Δl-cis(O) isomers exhibited some significant CD spectral behavior in the first d-d absorption band region. The CD spectra are discussed in relation to the sizes of the S–N and S–O chelate rings joining the chiral sulfur atom in the l-quadridentate-N,S,O2 ligand.
A Facile Synthesis of 3-(1-Benzyloxymethyl-3-hydroxypropyl)2,5-piperazinedione
Authors: Yamaura Masanori , Sadozai Khalid Khan , Yoshimura Juji 
Published: July 2006

Abstract
The title compound, a key intermediate for a total synthesis of bicyclomycin, was obtained from γ-butyrolactone through eight steps in ca. 4.4% overall yield.
Effects of Reduction Conditions on the Catalytic Activity of Rhodium Supported on TiO2 for the Hydrogenation of Carbon Monoxide:Favorable Metal-Support Interaction
Authors: Fujitsu Hiroshi , Ikeyama Nobuhide , Shigaki Yasunobu , Mochida Isao 
Published: July 2006

Abstract
Catalytic activity of Rh/TiO2 was influenced significantly by reduction conditions, the maximum activity per weight being obtained by reduction at 400°C for 2 h, in spite of limited adsorption abilities against reactant gases. The nature of Rh/TiO2 is sensitively modified to develop the most favorable metal-support interaction.
Electrogenerated Acid-catalyzed Cyclization of Isoprenoids
Authors: Uneyama Kenji , Isimura Akihiro , Torii Sigeru 
Published: July 2006

Abstract
Biogenetic-type cyclization of some isoprenoids (geranyl phenyl sulfone, methyl geranate, pseudoionone, and 6,10-dimethyl-2,5,9-undecatrien-4-one) has been performed by use of an electrogenerated acid in 1,2-dichloroethane.
Preparation of Hexafluorodisilane and Reactions of Hexafluorodisilane and Hexachlorodisilane with Sulfur Trioxide
Authors: Suresh Bettadapura Srinivasaiah , Padma Doddaballapur Krishnamurthy 
Published: July 2006

Abstract
Hexafluorodisilane has been prepared by the fluorination of hexachlorodisilane or hexabromodisilane by potassium fluoride in boiling acetonitrile, in yields approximating 45 and 60% respectively. Hexafluorodisilane has been characterised by infrared spectral data, vapour density measurements and analytical data. Both hexafluorodisilane and hexachlorodisilane are found to react with sulfur trioxide when heated to 400°C for 12 h. The products of reaction are silicon tetrafluoride, silica and sulfur dioxide with hexafluorodisilane while hexachlorodisilane in addition gives rise to hexachlorodisiloxane.
Nucleophilic Substitution of Tricoordinate Sulfur Atom of Sulfonium Salt with Retention of Configuration. Different Stereochemistry of Substitution by Amidate Anions
Authors: Kikuchi Katsuaki , Furukawa Naomichi , Moriyama Masaru , Oae Shigeru 
Published: July 2006

Abstract
Optically active N-substituted S-(o-methoxyphenyl)-S-phenylsulfilimines were obtained in moderate yields upon simple treatment of a mixture of o-methoxyphenyl phenyl sulfide and t-butyl hypochlorite in the presence of l-menthol and followed by amidate anions. Although some sulfilimines (N-tosyl-, N-benzoyl-, and N-(chloroacetyl)sulfilimines) were found to be rich in S-configuration around the sulfur atom, the others (N-(dichloroacetyl)-, N-(trichloroacetyl)-, and N-(trifluoroacetyl)sulfilimines) were found to be rich in R-configuration around the sulfur atom. In the displacement of l-menthyloxy group on the sulfur atom of the incipiently formed l-menthyloxysulfonium salt with p-toluenesulfonamidate, benzamidate, and chloroacetamidate anions, the respective N-acylsulfilimines of S-configuration were obtained by substitution with inversion of configuration, while N-acylsulfilimines having R-configuration were obtained by substitution of the same l-menthyloxysulfonium salt by polyhaloacetamidate anions such as dichloroacetamidate, trichloroacetamidate, and trifluoroacetamidate anions, with retention of configuration.
Oxidation of Lipids. VIII. Synergistic Inhibition of Oxidation of Phosphatidylcholine Liposome in Aqueous Dispersion by Vitamin E and Vitamin C
Authors: Niki Etsuo , Kawakami Akira , Yamamoto Yorihiro , Kamiya Yoshio 
Published: July 2006

Abstract
Vitamin E acted as an efficient antioxidant in the oxidation of soybean phosphatidylcholine liposome in an aqueous dispersion initiated by free radicals generated initially either in the aqueous phase or in the lipid phase. Vitamin E decayed linearly with time, and when it was exhausted, the oxidation proceeded rapidly at a similar rate to that in the absence of vitamin E. Vitamin C was also effective by itself in scavenging radicals in an aqueous phase, but it could not scavenge the radicals efficiently in a lipid bilayer. However, when vitamin E was located in phosphatidylcholine bilayer, the addition of vitamin C into an aqueous phase prolonged the period of suppression of oxidation and vitamin C reduced the rate of decay of vitamin E markedly even when the radicals were generated initially in the lipid region. Vitamin C was predominantly consumed linearly at first and vitamin E began to decay after vitamin C was exhausted. It was suggested that vitamin C could regenerate vitamin E by reacting with vitamin E radical during the oxidation of phosphatidylcholine liposome in an aqueous dispersion as observed in a homogeneous solution.
Nucleophilic Aminomethylation of Aldehydes with α-Amino Alkylsilanes
Authors: Tsuge Otohiko , Tanaka Junji , Kanemasa Shuji 
Published: July 2006

Abstract
Fluoride-induced desilylation of (α-phthalimido-, α-morpholino-, and α-acetamidobenzyl)silanes and a (phthalimidomethyl)silane generates the corresponding α-amino carbanions which add to a variety of aldehydes. The conversion of phthalimido group of the adducts into amino moiety leads to β-amino alcohols. This simple reaction sequence offers a new and general method of nucleophilic aminomethylation.
Electrochemical Conversion of 2,3-Butanediol to Acetaldehyde by Oxidative Cleavage by a Periodate/Iodate Redox Mediatory System
Authors: Yoshiyama Akiko , Nonaka Tsutomu , Baizer Manuel M , Chou Tse-Chuan 
Published: July 2006

Abstract
As electrochemical method was developed for converting 2,3-butanediol in dilute aqueous solutions to acetaldehyde by “in-cell” indirect anodic oxidation using a periodate/iodate redox mediatory system. Under optimum conditions, current efficiency for the desired acetaldehyde was close to 80% and the formation of by-products such as acetic acid, acetoin, and biacetyl was minimized or suppressed.
Kinetic Features of SERS Quenching by Underpotential Deposition (UPD) of Cd and Tl on Ag Electrodes
Authors: Watanabe Tadashi , Kawanami Osamu , Honda Kenichi 
Published: July 2006

Abstract
Surface-enhanced Raman scattering (SERS) in the Ag/pyridine system is quenched through a biphasic kinetics, after completion of submonolayer underpotential deposition (UPD) of Cd. This result is elucidated by invoking a quasi-reversible transformation of the initial SERS-active site into another by an attack, via surface diffusion, of deposited Cd, followed by irreversible unimolecular decomposition of the new site. From the SERS quenching data a value of about 10−17 cm2 s−1 was derived as the surface diffusion coefficient of Cd on the Ag surface. A similar but somewhat different quenching behavior is observed by UPD of Tl.
Reactions of Vinylphosphonates. 3. One-Pot Synthesis of Dienes and Their Analogues from Vinylphosphonates, Aldehydes and Diethyl Phosphonate
Authors: Minami Toru , Tokumasu Shigehumi , Hirao Ichiro 
Published: July 2006

Abstract
Functionalized dienes and tetraenes were synthesized in 26–63% yields by the one-pot reaction of the phosphoryl-stabilized carbanions, prepared from the Michael addition of diethyl lithiophosphonate to vinylphosphonates, with aromatic aldehydes. A similar reaction using phthalaldehyde gave 2-methylsulfonylnaphthalene (7) in 31% yield via an intramolecular double Horner-Wittig reaction.
Absolute Stereostructure Determination of Cladospolide A Using MTPA Ester Method
Authors: Hirota Hiroshi , Hirota Akira , Sakai Heiichi , Isogai Akira , Takahashi Takeyoshi 
Published: July 2006

Abstract
The absolute configuration of cladospolide A, a phytotoxic macrolide produced by a fungus Cladosporium cladosporioides, was determined as (4R,5S,11R,2E)-4,5-dihydroxy-2-dodecen-11-olide by means of MTPA method.
Facile Synthesis of 2-Phenyl-1,2-oxaphospholane and Its Related New Compounds. The Family of Deoxophostones and Deoxothiolphostones
Authors: Kobayashi Shiro , Suzuki Masato , Saegusa Takeo 
Published: July 2006

Abstract
2-Phenyl-1,2-oxaphospholane (1a), 2-phenyl-1,2-oxaphosphorinane (1b), 2-phenyl-1,2-thiaphospholane (1c), and 2-phenyl-1,2-thiaphosphorinane (1d) were prepared readily by the reaction of dichlorophenylphosphine with an ω-chloroalkanol or an ω-chloroalkanethiol followed by cyclization with the aid of lithium metal. Compounds 1b–d have been obtained for the first time.
Rate Constants and Mechanism for Reactions of Ketenes with OH Radicals in Air at 299±2K
Authors: Hatakeyama Shiro , Honda Shigeo , Washida Nobuaki , Akimoto Hajime 
Published: July 2006

Abstract
Rate constants for reactions of OH radicals with four kinds of simple ketenes (ketene, methylketene: MK, ethylketene: EK, and dimethylketene: DMK) were measured in 1 atm of air at 299±2 K by use of a competitive reaction method. The photolysis of CH3ONO in air was used to generate OH radicals. The rate constants for OH reactions obtained are (1.8±0.2)×10−11, (7.6±1.4)×10−11, (11±3)×10−11 and (10±3)×10−11 cm3 molecule−1 s−1 for ketene, MK, EK, and DMK, respectively. The major product was a carbonyl compound; HCHO from ketene, CH3CHO from MK, and CH3COCH3 from DMK; the yield was ≈80%, 72±17%, and 70±3%, respectively. It is proposed that the reaction proceeded mainly via an OH addition to the olefinic carbons of ketenes and the adduct decomposes to give a carbonyl compound and CO as final products in air.
The Electric Properties of VO2 Thin Films Doped with Other Metal Oxides under Water Vapor
Authors: Kera Yoshiya , Oonishi Tadashi , Imori Hisateru , Kida Shigeharu 
Published: July 2006

Abstract
The electric property of a pure VO2 thin films, prepared from a vanadium naphthenate by thermal decomposition, was examined preliminarily under various inorganic gas atmospheres, H2O, H2, O2, N2O, and NO2, at 20–200 °C. Only in the case of the H2O adsorption, did the conductivity-temperature curve change reversibly; in the other cases it changed irreversibly. With respect to the VO2 films doped with Na2O, ZrO2, Cr2O3, and TiO2, similarly, the conductivities changed reversibly with the water vapor adsorbed; the extent and the manner of these changes differed rather greatly depending upon the kind of metal oxides doped. In the Zr–VO2 film, which had a large conductivity (σ) and its gap (Δσ) at the transition point (Tt=60 °C) relative to the pure VO2 film, the electric property was almost unaffected by water–vapor adsorption. In the cases of the Cr– and Ti–VO2 films, with quite small σ and Δσ values relative to the pure VO2 film, on the contrary, the In σ–1/T curves decreased parallelly to less than about one-half of that under a vacuum throughout the temperature range. With the Na–VO2 film, the σ–1/T curve measured under water vapor gradually nears that under a vaccum with the elevation of the temperature to 200 °C. From the comparisons of the effects of the electric properties of these doped films on the water vapor adsorbed, the structural features of the films, especially the contact states in the boundary layer, were deduced favorably. Furthermore, a possibility of the application to a switching element working at about 60 °C was suggested for the Zr–VO2 film, and that to a fume sensor working at a temperature less than 200 °C, for the Cr– and Ti–VO2 films.
The Crystal and Molecular Structure of N-Ethylcarbazole
Authors: Kimura Toshihiko , Kai Yasushi , Yasuoka Noritake , Kasai Nobutami 
Published: July 2006

Abstract
N-Ethylcarbazole crystallizes in the orthorhombic system, space group Pbca with fairly large unit cell dimensions of a=7.971(1), b=24.615(3), c=56.587(5) Å, Dm=1.17 g cm−3, Dc=1.168 g cm−3 for Z=40. The structure was solved by the direct method and refined anisotropically by the least-squares procedure, R=0.062 for 5134 non-zero reflections. Five crystallographically independent molecules are not different from each other, the carbazole group is planar, and the ethyl group attached to the nitrogen atom is almost perpendicular to the carbazole ring. In the crystal, each carbazole ring makes a similar angle with the a axis [52 to 55°].