bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Control of the Particles of Magnetite
Authors: Matsuda Keizo , Sumida Masami , Fujita Kazumi , Mitsuzawa Shunmei 
Published: July 2006

Abstract
Fine particles of magnetite were prepared by the hydrolysis of urea. The effects of the amount of urea on the particles were investigated. The expected particles were prepared in the range 0.8 to 2.2 μm in size by controlling the amount of urea. Fine particles of magnetite of 0.8 μm in size were prepared from a solution with R=60 (R=urea/iron(III) mol ratio).
Fluorinated Tertiary Thio- and Selenoethers from the Reaction of Sulfenyl or Selenenyl Chloride with Perfluoropropene Dimers in the Presence of Alkali Fluoride
Authors: Suzuki Hitomi , Satake Hiroshi , Uno Hidemitsu , Shimizu Hiroaki 
Published: July 2006

Abstract
Perfluoro(1,1-dimethylbutanide) anion generated from hexafluoropropene dimers and alkali fluorides in dry N,N-dimethylformamide, reacts with arenesulfenyl or areneselenenyl chloride to give the corresponding aryl perfluoro(1,1-dimethylbutyl) sulfides or selenides in low to good yields.
1H NMR Studies on the Motion of Cations in the Three Solid Phases of Methylammonium Perchlorate Including Cationic Self-Diffusion in Its Highest-Temperature Solid Phase
Authors: Ishida Hiroyuki , Ikeda Ryuichi , Nakamura Daiyu 
Published: July 2006

Abstract
The temperature dependences of the second moment of 1H NMR absorptions, the 1H spin-lattice relaxation time, T1, and the 1H spin–spin relaxation time, T2, of CH3NH3ClO4 (CH3ND3ClO4) were observed in the three solid phases existing over a wide range of temperature. In the phase I stable above 451 K, the onset of the isotropic reorientation as well as the self-diffusion of the cations with the activation energy of 36 kJ mol−1 was observed. In the phase II stable between 451 and 321 K, no remarkable change in the motional state of the cation was observed, but the dynamical orientational disorder of perchlorate anions was expected to occur. In the phase III stable below 321 K, the correlated reorientation defined as the C3 reorientation of the cation having the rigid structure, was observed at lower temperatures for two nonequivalent cations in the crystal with small activation energies of 4.4 and 2.0 kJ mol−1. The uncorrelated reorientation in which both CH3 and NH3+ groups perform C3 reorientation independently could be observed at a higher temperature with the activation energy of 6.4 kJ mol−1. Nonexponential behavior appearing in the observation of T1 below 40 K could be explained by the presence of a contribution to 1H T1 from the rotational tunneling of the cation.
The Solubility of Benzene–Hydrocarbon Binary Mixtures in Water
Authors: Sanemasa Isao , Miyazaki Yoshiko , Arakawa Seiji , Kumamaru Masaya , Deguchi Toshio 
Published: July 2006

Abstract
The solubility in water at 25.0°C of benzene–hydrocarbon binary mixtures has been studied for different ratios between benzene and toluene, ethylbenzene, (o-, m-, p-)xylene, propylbenzene, chlorobenzene, and cyclohexane. Aqueous solutions saturated with mixed solutes were prepared by making use of the solute vapor. The solubility of individual constituent in the binary mixture was found to change linearly with mole fraction over a whole range of the composition. This is not the case for the benzene–cyclohexane system: the solubility of each component deviates positively from the linear change of solubility with composition. The solubility of each component of benzene–1-octanol mixture in water was also measured by adding the mixture of various compositions directly to water. The positive deviation for the solubility of each component was observed. The relationship between the 1-octanol/water partition coefficient of a solute and the aqueous solubility of pure liquid solute which forms a nonideal solution in 1-octanol was discussed.
The Synthesis and Crystal and Molecular Structures of [Pentaaquabis(1-hydroxy-2-naphthoato)neodymium(III)] (1-Hydroxy-2-naphthoate) Dihydrate, [Nd{C10H6(OH)CO2}2(H2O)5][C10H6(OH)CO2]·2H2O
Authors: Ohki Yoshiyuki , Suzuki Yasuo , Shimoi Mamoru , Ouchi Akira 
Published: July 2006

Abstract
The title complex was synthesized, and its crystal and molecular structures were determined by the single-crystal X-ray-diffraction method. It is triclinic, with the space group of P\bar1; the cell constants are a=20.621(4), b=22.288(5), c=7.724(1) Å, α=93.30(2), β=96.78(2), γ=107.43(2)°, Z=4, and the final R value is 0.048. Although there are two kinds of crystallographically independent complexes, their structures are almost the same, with only a slight difference in the orientations of the naphthalene rings of the ligands. Both of the central metal atoms are ennea-coordinated and are in the tricapped trigonal-prism geometry: two carboxylato ligands make four-membered chelate rings, and they are also ligated five water oxygen atoms. No carboxylate ions bridge the metal atoms, but the oxygen atoms of the ligands, isolated carboxylate ions, and the crystalline water molecules are linked through hydrogen bondings along the bc-plane. The metal atoms lie on a plane parallel to (100), and the planes are separated by the layers of the naphthalene rings of the naphthoate ions.
Isomerization and Racemization of the Tris(2,2′-bipyridine N,N′-dioxide)chromium(III) Complex
Authors: Kanno Hideaki , Fujita Junnosuke 
Published: July 2006

Abstract
Both racemic and optically active [Cr(bpdo)3](ClO4)3·1.5H2O (bpdo=2,2′-bipyridine N,N′-dioxide) were found to crystallize in the lel2·ob(Δ(λλδ), Λ(δδλ)) isomer. The complexes isomerized spontaneously to the lel3(Δ(λλλ), Λ(δδδ)) isomer upon dissolution in water with a rapid absorption spectral change, and then racemized (Δ\ightleftarrowsΛ) slowly. The rate constant for isomerization was 5.33×10−3 s−1 at 303.2 K, and that for racemization 1.93×10−4 s−1 at the same temperature. An intramolecular conformational inversion of the bpdo chelate ring (δ\ightleftarrowsλ) and an intramolecular twist mechanism were proposed for the isomerization and the racemization of the complex, respectively. Neither isomerization nor racemization was observed for [Cr(en)(bpdo)2]3+ in aqueous solution.
Methylation of Alcohols and Phenols Adsorbed on Silica Gel with Diazomethane
Authors: Ogawa Haruo , Hagiwara Toshikazu , Chihara Teiji , Teratani Shousuke , Taya Kazuo 
Published: July 2006

Abstract
Alcohols and phenols adsorbed on silica gel react with diazomethane and quantitatively afford the corresponding methyl ethers. Alumina and titanium dioxide are also effective adsorbents for the reaction.
Stereoselective Formation of Allyl Ethers by Reaction of Epoxides with Organic Chlorides under Liquid-Solid Phase-Transfer Catalysis
Authors: Gu Xue-Ping , Ikeda Isao , Okahara Mitsuo 
Published: July 2006

Abstract
A series of trans-3-chloroallyl ethers and trans-3-thioallyl ethers were stereoselectively synthesized in one step by the reaction of 1-chloro-2,3-epoxypropane or 2,3-epoxypropyl sulfides with alkyl chlorides in the presence of solid sodium hydroxide and quaternary ammonium salt as a phase-transfer catalyst. Phase-transfer catalytic hydroxide ion-initiation followed by stereoselective isomerization of the epoxide ring through β-elimination is postulated as the important part of the reaction pathway.
The Synthesis of 1,3-Dithiolane-2-thione Derivatives
Authors: Taguchi Yoichi , Yanagiya Koshin , Shibuya Isao , Suhara Yasuo 
Published: July 2006

Abstract
The reaction of 2,2-dimethylthiirane with carbon disulfide in the presence of triethylamine was accelerated under high pressure to give 4,4-dimethyl-1,3-dithiolane-2-thione nearly quantitatively. The activation volume of this reaction at 40 °C was estimated to be −41 ml mol−1. The rate of the reaction was proportional to the amount of triethylamine when a limited amount of triethylamine was used. The reaction of 2-methylthiirane, 2-hexylthiirane, 1,2-epithiocyclohexane, and 2-phenylthiirane with carbon disulfide gave the corresponding 1,3-dithiolane-2-thione derivatives in good yields. 2-Chloromethylthiirane was less reactive to carbon disulfide than other thiiranes under high pressure. Tertiary amines such as N,N-dimethylethylamine, pyridine, and N-methylmorpholine were good catalysts of the reaction.
New Birch Type Reduction. Halogen or Halides-Activated Reduction of Disulfides to Thiols with Aluminium in Liquid Ammonia
Authors: Sato Ryu , Akaishi Ryouichi , Goto Takehiko , Saito Minoru 
Published: July 2006

Abstract
Aromatic and aliphatic disulfides were reduced to the corresponding thiols in high yields by new halogen or halides-activated Birch type reduction with aluminium in liquid ammonia.
Thermal and Photochemical Electron-Transfer Reactions of 4-Chlorobiphenyl with Lithium Diisopropylamides and Diisopropylamine
Authors: Tanaka Yoshio , Tsujimoto Kazuo , Ohashi Mamoru 
Published: July 2006

Abstract
A reaction of 4-chlorobiphenyl with lithium diisopropylamide in a polar solvent gave 3- and 4-(diisopropylamino)biphenyl together with biphenyl, similar to the case of photoinduced reactions of 4-chlorobiphenyl with diisopropylamine. A common electron-transfer mechanism is proposed.
Electrogenerated Chemiluminescence. 50. Electrochemistry and Electrogenerated Chemiluminescence of Micelle Solubilized Os(bpy)32+
Authors: Ouyang Jiangbo , Bard Allen J 
Published: July 2006

Abstract
The oxidative electrochemistry and electrogenerated chemiluminescence (ECL) of Os(bpy)32+ were studied in the presence of sodium dodecyl sulfate (SDS), Triton X-100, and cetyltrimethylammonium bromide (CTAB) in aqueous solutions. Variation of supporting electrolyte (NaCl) concentration affected the interaction between Os(bpy)32+ and the surfactants. The measurement of oxidation peak current (ipa) and ECL intensity at different NaCl concentrations suggested a strong interaction of Os(bpy)32+ with SDS. Above the critical micelle concentration (cmc) the strong hydrophobic interaction of Os(bpy)32+ and the SDS micelle core greatly suppresses both ipa and the ECL intensity. The interaction of Os(bpy)32+ with CTAB micelle is much weaker because of electrostatic effects. Triton X-100 micelles do not interact with Os(bpy)32+.
Structural Studies of Liquid 1,1,1-Trichloroethane by Means of X-Ray Diffraction
Authors: Nishikawa Keiko , Iijima Takao 
Published: July 2006

Abstract
The X-ray scattering intensities from liquid 1,1,1-trichloroethane (TCE) were measured at room temperature by the energy-dispersive method. By the use of the real space expansion and the reciprocal space expansion based on the local lattice structure model, structure simulation studies for TCE were carried out. A bcc model with a random orientation of the methyl group reproduces the experimental intensities well. The number of molecules in the structure region, n, was determined by a trial-and-error method, and a least-squares refinement was carried out to determine the following four parameters; the lattice constant of the bcc cell, a; the Prins parameter, D; the radius up to the continuous region, Rc; and its damping factor, lc. The refined parameters with the standard deviations in parentheses are: a=6.78 (0.11) Å, D=0.049 (0.009) Å, Rc=12.70 (0.48) Å, and lc=1.76 (1.22) Å with n=51.
The Chiral Recognition of Optically Active Poly(triphenylmethyl methacrylate) Derivatives as Stationary Phases for HPLC
Authors: Okamoto Yoshio , Yashima Eiji , Ishikura Motoshi , Hatada Koichi 
Published: July 2006

Abstract
Four meta-halogen- or meta-methyl-substituted optically active poly(triphenylmethyl methacrylate) [poly(TrMA)] derivatives with a one-handed helical structure were coated on macroporous silica gel and their chiral-recognition abilities as stationary phases for high-pherformance liquid chromatography were investigated with methanol or hexane–2-propanol (95:5(v/v)) as the eluent. The chiral-recognition abilities of poly(m-fluorophenyldiphenylmethyl methacrylate) and poly(m-chlorophenyldiphenylmethyl methacrylate) were slightly low compared with that of poly(TrMA) when methanol was used as the eluent. Poly[tris(m-chlorophenyl)methyl methacrylate] [poly(m-Cl3TrMA)] showed no resolving ability, although poly[tris(m-tolyl)methyl methacrylate] [poly(m-Me3TrMA)] had an effective chiral recognition ability and resolved some racemates more efficiently than poly(TrMA). When hexane–2-propanol (95/5) was used as the eluent, the optical-resolution abilities of all these chiral polymers except for poly(m-Cl3TrMA) were rather similar to that of poly(TrMA) under the same eluent system. The chiral-adsorbing sites are considered to be the chiral triarylmethyl propellers in the methanol system; carbonyl groups may also be involved in the hexane–2-propanol system. The difference in the chiral-recognition abilities of the two tri-substituted chiral polymers were ascribed to their different propeller structures and/or the different conformations of their carbonyl groups. The optical-resolution abilities of poly[TrMA-co-(m-Cl3TrMA)] and poly[TrMA-co-(m-Me3TrMA)] were also investigated. From the results, the mechanism of the separation of enantiomers on poly(TrMA) was discussed.
Kinetics of Substitution of Aqua-Ligands from cis-Diaquobis(ethylenediamine)cobalt(III) Complex by β-Alanine and Dl-Valine in Various EtOH–Water Mixtures
Authors: Chatterjee Debabrata , De G S 
Published: July 2006

Abstract
The kinetics of above titled reaction has been studied spectrophotometrically in various water–ethanol mixtures at different temperatures (45–60 °C). The following rate law has been established in the pH range 3.2 to 4.5.
\fracd[Co(en)2(H2O)(LH)3+]dt=\frackaKE[Co(en)2(H2O)23+]T[LH]1+KE[LH]
where LH represents the zwitterionic form of the amino acids viz. β-alanine and Dl-valine. KE is the ion-pair equilibrium constant between substrate complex ion and zwitterionic ligand the values of which increase with the increase of organic component of medium, where reverse is true for ka, the interchange rate constant from outersphere complex to innersphere product. It was observed that at higher ligand concentration a limiting rate is attained, which has been explained due to completion of ion-pair formation. Increasing effect of pH and special catalytic effect of NO3− have been observed. Activation parameters (ΔH\eweq and ΔS\eweq) have been calculated and compared with isotopic water exchange reaction and other deaquation reactions. A dissociative interchange mechanism (Id) involving ion-pair formation has been suggested.
Selective Synthesis of Ethylene by Dehydrogenative Coupling of Methane by Use of Thermal Diffusion Column
Authors: Yamaguchi Tatsuaki , Saito Chiaki 
Published: July 2006

Abstract
Ethylene was found to be obtained dehydrogenatively from methane in extremely high selectivities (91.5% at 9.4% conversion of methane) with the downward introduction to the modified thermal diffusion column with electrically heated tungusten wire at 1200 °C.
X-Ray Crystal Structure and Electrochemical Property of a Novel Monohydroxo-Bridged Binuclear Cobalt(II) Complex with N,N′,N″,N'″-Tetrakis(2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane
Authors: Mikuriya Masahiro , Kida Sigeo , Kohzuma Takamitsu , Murase Ichiro 
Published: July 2006

Abstract
The crystal structure of a binuclear cobalt(II) complex of N,N′,N″,N'″-tetrakis(2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane (taec), [Co2(taec)(OH)](ClO4)3, was determined by the single-crystal X-ray diffraction method. The two cobalt ions are bridged by a single hydroxide ion in the cavity of taec. The cyclic voltammogram showed an irreversible profile with two anodic peaks at ca. 1.4 and 1.8 V vs. SCE.
Stereospecific Synthesis of 3-Oxo-α-bourbonene and the Cisoid Isomer for Structural Determination of the Toxic Component of Lansium domesticum
Authors: Uyehara Tadao , Suzuki Ichiro , Yamamoto Yoshinori 
Published: July 2006

Abstract
The cis-cisoid-cis isomer of 3-oxo-α-bourbonene, (1), the original structure proposed for the toxic principle of Lansium domesticum, has been prepared from (−)-mintsulfide. Neither spectral data of 1 nor of 3-oxo-α-bourbonene itself, derived from β-bourbonene, are not identical with those of the toxic componet.
A Systematic Investigation of the Effects of Axial Ligands and Peripheral Substituents on the Electronic Structures of Zinc(II) Tetraphenylporphyrin π-Cation Radicals: Electrochemical EPR and Spectroscopic Observation
Authors: Ichimori Kohji , Ohya-Nishiguchi Hiroaki , Hirota Noboru 
Published: July 2006

Abstract
A detailed study of the effect of axial ligand and peripheral substituent on the π-system of zinc(II) tetraphenylporphyrin π-cation radical has been made using an electrochemical EPR technique. It is confirmed from the EPR spectra that most of the anions and bases examined coordinate the radicals axially. The spin density on the nitrogen nuclei in the radicals increases with the polarizability of the axial ligand estimated from the optical spectra of the parent neutral complexes. For the fourteen complexes with different substituents on the phenyl groups examined here, there is a linear correlation between the Hammett substituent constant and the spin density. It is also shown that the para position of the phenyl group carries the spin density comparable to that of the ortho position, which indicates considerable conjugation between the porphyrin ring and the phenyl groups. In most cases, there exist two kinds of radical species which give rise to broad and sharp EPR spectra at low temperature. It is suggested that the difference in the motional states of the phenyl groups in the radicals is responsible for the different EPR spectra.
Effect of the N-Methylation of Dodecylammonium Chloride on the Adsorption from Its Micellar Solution
Authors: Aratono Makoto , Okamoto Toru , Ikeda Norihiro , Motomura Kinsi 
Published: July 2006

Abstract
The surface tension of the aqueous solution of dodecylmethylammonium chloride (DMAC) and dodecyldimethylammonium chloride (DDAC) was measured as a function of temperature under atmospheric pressure at concentrations below and above the critical micelle concentration (cmc). The entropy and energy of adsorption from the monomeric state in the aqueous solution and the micellar state were evaluated by applying the thermodynamic equations of adsorption to the surface tension values. The thermodynamic quantities were compared with those of the aqueous solutions of dodecylammonium chloride (DAC) and dodecyltrimethylam-monium chloride (DTAC). It was found that the successive N-methylation of DAC has a considerable effect on the adsorbed film with changes in its surface density, entropy, and energy brought about by changes in the geometry and the hydrophilicity of the polar head group.
The Solubility of Peptide Intermediates in Organic Solvents. Solubilizing Potential of Hexafluoro-2-propanol
Authors: Narita Mitsuaki , Honda Shinya , Umeyama Hiroshi , Obana Satoshi 
Published: July 2006

Abstract
The solubility of peptides to be insoluble in EtOH, MeOH, DMF, DMA, NMP, DMSO, and HMPA was examined in HFIP, sulfolane, TMP, PC, and a mixture of 5–10% HFIP–CH2Cl2 (v/v). HFIP has the highest solubilizing potential, followed by HMPA and DMSO, while the solubilizing potential of sulfolane, TMP, and PC is lower than that of HMPA, DMSO, DMF, and NMP and is close to that of MeOH and EtOH. The solubility of the peptides in the mixture of HFIP–CH2Cl2 marvelously is as high as that in HFIP alone. The solvent-titration study in CH2Cl2–polar solvents clearly indicated that the solubility of peptides having a β-sheet structure in organic solvents was independent of the polarity of the solvents but was strongly dependent on their hydrogen donating and accepting ability. The conformation of the peptides in the mixture of HFIP–CH2Cl2 and in HFIP alone was examined using the IR and CD spectroscopies, respectively.
Synthesis and Acid-Catalyzed Ring Opening of 1-Alkenyl Cyclopropyl Ketones
Authors: Tsuge Otohiko , Kanemasa Shuji , Otsuka Tatsuya , Suzuki Toshiro 
Published: July 2006

Abstract
1-Alkenyl cyclopropyl ketones, when activated by cation-stabilizing substituents at the ring carbon or at the terminal carbon of the enone moiety, undergo polyphosphoric acid-catalyzed ring enlargement producing cyclopentanone or cyclohexenone derivatives. Similar acid-catalyzed ring opening of 1-alkenyl 2-phenoxycyclopropyl ketones offers a convenient and effective synthesis of 4-oxo-5-alkenals and their dioxolaneprotected derivatives.
An Ab Initio Molecular Orbital Study of Pyridyl Radicals
Authors: Kikuchi Osamu , Hondo Yuji , Morihashi Kenji , Nakayama Mitsunobu 
Published: July 2006

Abstract
Open-shell RHF and UHF ab initio calculations were carried out for 2-, 3-, and 4-pyridyl radicals in order to determine their molecular structures and relative energies. The minimal STO-3G basis set was used for the structure optimization, while the 4-31G basis set was used for the energy evaluation. The 2-pyridyl radical has the lowest energy, although the energy differences among these three isomers were very small. The possibility of a Π-ground state in pyridyl radicals was rejected.
Kinetics of the Denaturation of Ovalbumin and S-Ovalbumin by Alcohols
Authors: Murakami Kiyofumi 
Published: July 2006

Abstract
The kinetics of denaturation of ovalbumin and S-ovalbumin by butyl alcohol isomers (butyl alcohol, isobutyl alcohol, s-butyl alcohol, and t-butyl alcohol) have been studied. The reactions were characterized as first order with respect to the protein and 11th order for the alcohols, irrespective of the kind of protein or alcohol. The rate constant was, however, significantly reduced by the branching of the alcohol structure and by the conversion of native ovalbumin to S-ovalbumin. The measurements were also performed on ovalbumin and S-ovalbumin whose SH groups were blocked from SH\ightleftharpoonsS–S exchange reactions by modification with iodoacetamides. By the conversion to S-ovalbumin, the modified protein also exhibited a considerable resistivity against denaturation, suggesting that SH\ightleftharpoonsS–S exchange reactions play no essential role in the formation of S-ovalbumin. On the basis of these results as well as determined activation parameters, the mechanism of the denaturation is discussed in the light of a combination of the hydrophobic interactions, between hydrophobic residues of the proteins and the alcohol molecules, and the fluctuations of the protein structures.
Pulse Radiolysis Studies of Solvent Radical Cations in Liquid 1,2-Dichloroethane
Authors: Sumiyoshi Takashi , Sugita Naoki , Watanabe Kazuyuki , Katayama Meiseki 
Published: July 2006

Abstract
Transient absorption spectra with maxima at 270 and 550 nm were observed in liquid pure 1,2-dichloroethane by means of ps and ns pulse radiolysis. The broad absorption band with a maximum around 550 nm decayed according to a first-order reaction with t1⁄2=0.2 ns in ps pulse radiolysis and t1⁄2=200 ns in ns pulse radiolysis. These short lived species were attributed to solvent cations on the basis of scavenger experiments. The slowly decaying species with t1⁄2=1.2 μs which absorbs around 400 nm superimposed on the 550 nm band, was tentatively assigned to carbocations. The 270 nm band formed during and after the electron pulse decayed over several microseconds by second-order kinetics. Those radicals which were produced by the dissociative electron attachment to the solvent and by the reaction of cations were responsible for this UV band.