bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reexamination of the Molecular Size Dependence of Diffusivities of Hydrocarbons in Natural Rubber
Authors: Kawakami Mitsuyasu , Iwanaga Hideaki , Kagawa Shuichi 
Published: July 2006

Abstract
Diffusion coefficients at zero concentration, D0, for hydrocarbon vapors in natural rubber have been determined, and their dependence on the size and shape (or length) of the penetrants has been reexamined. For normal hydrocarbons, D0 decreased gradually with increasing the number of carbon atoms up to 5 and then leveled off. For branched hydrocarbons, such as iso- and neo-paraffins, D0 was considerably lower than that for the corresponding normal ones. The dependence of D0 on the size and shape of penetrants could be explained by assuming that the principal resistance to diffusion is defined by the cross-sectional area at the most bulky portion of the major axis and also that an additional resistance due to the molecular length contributes for relatively lower hydrocarbons. The latter resistance was practically negligible for hydrocarbons with more than 4 carbon atoms in the major chain. The effective cross-sectional dimension could be estimated successfully in terms of the group dimension of Pauling.
The Electronic Absorption and Emission Spectra of Biphenylene-2,3-dione in Solutions
Authors: Kuboyama Akira 
Published: July 2006

Abstract
The electronic absorption and MCD spectra and phosphorescence spectra at 77 K, in solutions, have been studied by the use of P-P-P-method calculations. The longest-wavelength S–S ππ* band, near 370 nm, is proved to consist of two ππ* bands, the 1A1 and 1B2 bands. The nπ* absorption, and phosphorescence bands in various kinds of solutions are compared in many respects with those of the o-quinones previously studied.
The Reaction of Magnesium Hydroxide with Soluble Silica under Hydrothermal Conditions below the Critical Temperature
Authors: Muraishi Haruto 
Published: July 2006

Abstract
Mg(OH)2 powder packed into a basket was placed apart from solid SiO2 in an autoclave so that the SiO2 might react with the solid Mg(OH)2 in the state of soluble silica. At given temperatures of 250–360 °C, the Mg(OH)2 changed into talc(Mg3Si4O10(OH)2) through serpentine(Mg3Si2O5(OH)4): the reaction was a first-order consecutive-irreversible reaction which can be represented as:
Mg(OH)2\overset+SiO2→ Mg3Si2O5(OH)4\overset+SiO2→ Mg3Si4O10(OH)2.
The reaction rate of serpentine into talc as a single reaction was also first-order. The formation of serpentine was much faster than that of talc. The reaction rate depended on the silica concentration in the hydrothermal solution rather than on the reaction temperature. In the course of the reaction, the crystallite size of the Mg(OH)2 and the serpentine was hardly changed. In addition, the crystallite size of Mg(OH)2 did not affect that of the resulting serpentine. From these results, the rate-limiting step is presumed to be the formation of the crystal nuclei of the serpentine or talc.
Electrochemical Oxidation and Reduction of Flavin Mononucleotide Adsorbed on a Mercury Electrode Surface
Authors: Kakutani Tadaaki , Kano Kenji , Ando Shinji , Senda Mitsugi 
Published: July 2006

Abstract
The electrochemical redox reaction of flavin mononucleotide (FMN) adsorbed on a hanging mercury drop electrode was studied in a pH 6.9 phosphate buffer and a pH 4.9 acetate buffer by means of cyclic d.c. and phasese lective a.c. voltammetry. Both the oxidized and reduced forms of FMN arc strongly adsorbed on the electrode surface, and a stable adsorption layer of FMN((FMN)ad) is formed. The cyclic d.c. and a.c. voltammetric behavior of (FMN)ad is explained by equations for a two-step one-electron surface redox reaction. The formal standard redox potentials, semiquinone formation constants, and charge transfer-rate constants of the surface redox reaction of FMN at the mercury electrode were determined.
Phase Transition in Ammonium-d4 Sulfate as Studied by Heat Capacity Measurements between 3 and 300 K
Authors: Higashigaki Yoshiyuki , Chihara Hideaki 
Published: July 2006

Abstract
Molar heat capacities were determined of (ND4)2SO4 between 2.8 and 301 K. The phase transition at 223.94±0.03 K is of the first-order with a long tail extending down to 160 K. The overall heat and entropy of transition are 4270 J mol−1 and 20.35 JK−1 mol−1, respectively, the first-order portion contributing only 40%. The contraction of the molar volume at the transition was evaluated as 0.33 cm3 mol−1. The enthaply to misorient ions in an otherwise perfectly ordered lattice was derived from the low-temperature tail of the anomalous heat capacity. It was 12.0 kJ/mol of (ND4)2SO4, in reasonable agreement with 16 kJ mol−1 derived from O’Reilly-Tsang’s mean field theory. The present results support the order-disorder mechanism of the transition.
On the NMR Spectra of Some Substituted Pyridinium 2-Pyridylcarbonylmethylides
Authors: Matsubayashi Gen-etsu 
Published: July 2006

Abstract
The partial double-bond character of the ylide carbon-pyridinium nitrogen bond is discussed on the basis of the 1H and 13C NMR spectra of 4-cyano-(YCN), 4-methyl- (Ypic), and 3,5-dimethylpyridinium 2-pyridylcarbonylmethylide (Ylut). The α-proton signals of the 4-cyanopyridinium ring of YCN have been separately observed at low temperatures, indicating a hindered rotation around the ylide carbon-pyridinium nitrogen bond.
Separation of Metals on Sulfonated Diphenyl Phosphonate–Formaldehyde Resin in HCl–Organic Solvent Systems
Authors: Mori Hidehiko , Fujimura Yoshikazu , Takegami Yoshinobu 
Published: July 2006

Abstract
The distribution coefficients of several metal ions have been measured on sulfonated diphenyl phosphonate–formaldehyde resin in HCl–water miscible organic solvent solutions. Differences in the distribution coefficients are large enough to develop multicomponent separations. Particularly in HCl-propanone systems the separation of a complex mixture, Cd(II)–Zn(II)–Pb(II)–Cu(II)–Co(II)–Mn(II)–Mg(II), can be carried out chromatographically by sequential elution.
Potential Gradient Detector for Capillary Type Isotachophoresis
Authors: Nishiyama Fumitaka , Hirokawa Takeshi , Kiso Yoshiyuki 
Published: July 2006

Abstract
The potential gradient detector previously reported has been improved as regards mechanical stability and the contaminated electrodes can be easily exchanged with new ones. The linearity of step-height holds below the electrode voltage of 1.2 V (0.005 mol dm−3 aq HCl). The detection limit was 2.5×10−10 mol for adipic acid.
Synthesis of Thiol Esters by Carboxylic Trichlorobenzoic Anhydrides
Authors: Kawanami Yasuhiro , Dainobu Yuichiro , Inanaga Junji , Katsuki Tsutomu , Yamaguchi Masaru 
Published: July 2006

Abstract
Thiocarboxylic S-esters were obtained rapidly and in high yields by treating the mixed anhydrides prepared from 2,4,6-trichlorobenzoyl chloride and carboxylic acid, with various types of thiols in the presence of 4-dimethylaminopyridine.
Studies on the Synthesis of Sydnone Derivatives and Their Properties. XV. Synthesis of 4-Sydnonylmethyl Acetates
Authors: Yeh Mou-Yung , Tien Hsien-Ju , Chou Jiun-Tzer , Nonaka Tsutomu 
Published: July 2006

Abstract
The convenient methods for the synthesis of 4-sydnonylmethyl acetates from N-(4-sydnonylmethyl)morpholines, 4-sydnonylmethanols, or bis(4-sydnonylmethyl) ethers are described.
Effect of Ammonia Pre-treatment on Catalytic Activity of Metal Halide Catalyst for Reduction of Nitrogen Monoxide
Authors: Nishijima Akio , Kiyozumi Yoshimichi , Kurita Minoru , Hagiwara Hiroyuki , Ueno Akifumi , Sato Toshio , Todo Naoyuki 
Published: July 2006

Abstract
Effects of ammonia pre-treatment on catalytic activities of metal halides for the reduction of nitrogen monoxide are investigated in order to obtain highly active catalysts at lower temperatures. By the pre-treatment with NH3, some supported metal halide catalysts such as CeCl2, MnCl2, TiCl4, FeBr3, and CuCl2, showed higher activities than untreated ones.
Hydration of Quaternary Phosphonium Bromides, Bu4−nPhnPBr, in Chloroform
Authors: Wakabayashi Toshiki , Takaizumi Katsuko 
Published: July 2006

Abstract
Studies have been carried out on the hydration of quaternary phosphonium bromides, Bu4−nPhnPBr(n=0–4), in the chloroform phase by means of distribution equilibrium and 1H NMR spectroscopy, in order to clarify the difference between the alkyl- and aryl-substituted ions in ion–water interactions. The hydration constant for these bromides in the chloroform phase increases gradually from Bu4PBr to Bu2Ph2PBr, and then rapidly to BuPh3PBr and to Ph4PBr. The free energy of transfer from water to chloroform was evaluated for the non-hydrated species of the phosphonium bromides in the chloroform phase, the lowest being that for Bu2Ph2PBr. From 1H NMR spectra for water in the chloroform phase, it is concluded that the hydrated water molecule is hydrogen bonded with the anion of the onium salts. In the case of phenyl-rich cations such as BuPh3P+, Ph4P+, and Ph4As+ the water molecule occupies a site so close to the central atoms that it undergoes diamagnetic effects of phenyl groups. With phenyl-rich cations such hydration will play a certain role in their aqueous solutions.
New Scale of the Ionic Character of the Chemical Bond Using Multiconfiguration SCF Wave Functions
Authors: Ishida Kazuhiro , Kadowaki Shuichi , Yonezawa Teijiro 
Published: July 2006

Abstract
Two-configuration SCF wave functions constructed with multiconfiguration SCF localized-orbitals are obtained for several molecules, cations, and anions. The weights of the valence-bond resonance-structures are obtained from the wave functions for these molecules and molecular ions. A new formula of the ionic character of a chemical bond is proposed using these weights. For these neutral molecules, the values calculated from this formula are consistent with Pauling’s scale of the ionic character. The present formula is shown to be applicable even for molecular ions.
A New Interpretation of the Fast Relaxation in a Micellar Solution
Authors: Inoue Tohru , Tashiro Ryoichi , Shimozawa Ryosuke 
Published: July 2006

Abstract
Some contradictions are pointed out in the kinetic parameters of the fast relaxation in a micellar solution deduced from the previously proposed kinetic models. A modification of the previous models is proposed. The proposed model eliminates the contradictions and leads to a consistent interpretation of the experimental results.
The Effect of Crystallite Size of Nickel on the Enantioselectivity of Modified Nickel Catalysts
Authors: Nitta Yuriko , Sekine Fumimaro , Imanaka Toshinobu , Teranishi Shiichiro 
Published: July 2006

Abstract
Enantioselective hydrogenation of methyl acetoacetate to methyl 3-hydroxybutyrate with various unsupported nickel catalysts modified by (2R,3R)-tartaric acid was studied under mild conditions in order to elucidate the dependence of the selectivity upon the surface states of the catalysts. The catalyst with the larger crystallite size has the higher enantioselectivity, presumably because of the higher probability to obtain large ensembles of regularlyarranged nickel atoms in the catalyst surface for the modifier to adsorb strongly and regularly. The nickel boride catalyst has very low enantioselectivity, mainly due to its amorphous structure. The detrimental effect of additives (B, P, and Al in Ni–B, Ni–P, and R–Ni catalysts) was explained as the effect of their lowering the crystallinity of the catalysts.
A Dilatometric Study of Mesomorphic Transitions in Cholesteryl Oleyl Carbonate and Cholesteryl Oleate
Authors: Nakahara Masaru , Yoshimura Yosuke , Osugi Jiro 
Published: July 2006

Abstract
The volumetric behaviors of cholesteryl oleyl carbonate (COC) and cholesteryl oleate(CO) were investigated around the smectic(Sm)-cholesteric(Ch) and cholesteric-isotropic(I) transitions by using chromatographically purified materials. Both transitions showed marked pretransition phenomena in COC and CO. The transition volumes(ΔV) are; for COC ΔVSm-Ch=0.34 cm3 mol−1 at 22.8 °C and ΔVCh-I=0.66 cm3 mol−1 at 37.5 °C and for CO ΔVSm-Ch=0.88 cm3 mol−1 at 45.4 °C and ΔVCh-I=0.88 cm3 mol−1 at 50.7 °C. The Sm-Ch and Ch-I transitions are first order as predicted by mean-field theories. The pretransition volume around the Ch-I transition can be treated by the Landau-de Gennes theory for the first-order phase transition.
Observation of Mutual Diffusion Coefficients and Cooperative Motions in Binary Solutions of t-Butyl Alcohol–Water and 2-Butoxyethanol–Water
Authors: Ito Nobuyuki , Saito Koichi , Kato Tadashi , Fujiyama Tsunetake 
Published: July 2006

Abstract
Rayleigh scattering spectra were observed for the binary solutions of t-butyl alcohol(TBA)–water and 2-butoxyethanol (BE)–water. The observed line-widths were reduced to mutual diffusion coefficients. The observed concentration dependencies of the mutual diffusion coefficients were well explained by postulating the existence of “moving units”— a group of molecules which move together for a time much longer than the velocity autocorrelation time. The structure of the moving units which are formed in the TBA–water solution was (H2O)20TBA for XTBA\lesssim0.05, and 4(H2O)20TBA for XTBA\gtrsim0.05, where XTBA is the mole fraction of TBA. For the BE–water solution, the structure was found to be (H2O)50BE for XBE\lesssim0.02 and 3(H2O)50BE for XBE\gtrsim0.02. These results were compared with the results which had been obtained from the concentration dependencies of the mean-square concentration fluctuation values.
Thermodynamic Study of NH4Br and ND4Br Crystals under Constant High-pressures
Authors: Watanabe Kazuo , Oguni Masaharu , Matsuo Takasuke , Suga Hiroshi , Seki Syûzô 
Published: July 2006

Abstract
Heat capacities and volumes of NH4Br and ND4Br crystals were measured in the temperature range from 100 to 260 K at several constant pressures up to 110 MPa with a special attention paid to the behaviors around the point of ND4Br at 66 MPa and 202 K. The experimental results at an atmospheric pressure were in good agreement with the previously reported ones. The δ-γ and δ-β phase transitions were accompanied with expansion of the volume while the γ-β phase transition with contraction. Detailed phase diagram obtained for ND4Br disclosed that there was no maximum in any branch of the transition lines. The triple point was represented essentially as the point of intersection of the three straight lines. There was no pressure dependence of the total entropy of transition from the δ to β phase. The entropy values can be explained by the mechanism of the order-disorder change in the orientations of NH4+ tetrahedra. The existence of the heat capacity anomaly in the high temperature side of the δ-γ phase transition was discussed as due to the spatial fluctuation of domains of the γ and δ phases. An argument was put forward that the observed δ-γ phase transition was probably superheated. An additional anomalous heat-capacity peak was observed just below the triple point pressure in between the temperatures of the δ-γ and γ-β phase transitions, and explained in terms of the effects of the superheating in the δ-γ phase transition and of the coexistence of the δ and γ phases domains in the crystal.
The Electronic Structures of Linear Dicyano Complexes
Authors: Sano Mitsuru , Adachi Hirohiko , Yamatera Hideo 
Published: July 2006

Abstract
Molecular orbital (MO) calculations in the discrete variational Xα (DV-Xα) scheme have been made on linear dicyano complexes, [Ag(CN)2]−, [Au(CN)2]−, and [Hg(CN)2], to clarify their electronic structures. The valence X-ray photoelectron spectra (XPS) for these compounds are also reported. The calculated energy levels are consistent with the XPS results. The relative magnitudes of the bond overlap populations show a good correlation with those of the force constants obtained from infrared data. The calculated MO features show that the mixing of the metal (n+1)s orbital is important in stabilizing the linear L–M–L bonds, especially in the partial cancellation of the antibonding character of the σg-type highest occupied molecular orbital.
The Continuous Determination of Filtered Chemical-oxygen Demand with Potassium Dichromate by Means of Flow-injection Analysis
Authors: Korenaga Takashi 
Published: July 2006

Abstract
A useful method, based on the principle of flow-injection analysis, whose flow system is physically analyzed to operate the apparatus, is proposed for the continuous and rapid determination of chemical-oxygen demand (COD) as a dichromate value in organic-waste-water samples. Potassium dichromate in sulfuric acid (1+2) is pumped as an oxidizing and spectrophotometric reagent stream, and d-glucose is successfully used as a standard substance for COD. A redox reaction between potassium dichromate and organic COD substances is carried out at 100 °C in the poly(tetrafluoroethylene) tubing (0.6 mm i.d.×50 m) of the system. The peaks, obtained at 445 nm in the recordings, show a good reproducibility over a wide range of COD values. A sampling rate of 10 samples per hour is achieved even when the residence time is 30 min. The precision with this method is 1.3%. Chloride up to 200 mg dm−3 does not interfere with the determination even if silver or mercury salts are not added.
Kinetics of Thermal Pyridine Dissociation of Ni(N-arylsalicylideneaminato)2(pyridine)2 in Solid Phase
Authors: Miyokawa Kikuo , Hirashima Hidenori , Masuda Isao 
Published: July 2006

Abstract
The kinetics of the thermal pyridine dissociation reactions of Ni[N-(R-C6H4)salam]2py2, where R=H(1), p-F(2), p-CH3O(3), p-CH3(4), p-Cl(5), and p-Br(6), in solid phase, were analyzed by the isothermal weight-loss measurements. On pyrolysis, these pyridine adducts with an octahedral coordination geometry of Ni(II) liberated pyridine to leave products with the formula Ni[N-(R-C6H4)salam]2. The product obtained from 2 was the diamagnetic monomer, those from 4–6 were paramagnetic polymers with μeff=(3.11–3.30) μB, and that from 3 was paramagnetic with an intermediary moment of μeff=1.45 μB. Reaction mechanisms were different depending on the nature of R: 2 followed the contracting disk equation with E=163 kJ/mol; 3–6 followed the contracting disk equation in the initial period of the reaction (the Ea values were 97 for 3, 134 for 4, 173 for 5, and 172 kJ/mol for 6) and then all except 3 followed Jandar’s equation, in the subsequent period. These Ea values were considered to reflect the bond stability between the central Ni(II) ion and the axial pyridine ligands; these values increased with an increase in the electron-withdrawing property of R. The pyridine dissociation reaction may give rise to the complexes of the monomeric square-planar or to those of the associated, polymeric octahedral structure. Which result occurs does not depend only on the tendency of the central Ni(II) ion to accept, at the apical positions, the coordinate bond from the adjacent molecules.
Stereochemistry of Bis[N-(2,6-diisopropylphenyl)salicylideneaminato]copper(II) and nickel(II) Complexes
Authors: Yamada Shoichiro , Yamanouchi Kuniko 
Published: July 2006

Abstract
Bis[N-(2,6-diisopropylphenyl)salicylideneaminato]copper(II) and nickel(II) complexes have been synthesized. Their configurations in the solid state, in chloroform, and in pyridine have been examined and discussed in comparison with those of the related complexes.
Spirans. XXII. Spiroconjugation in Heteraspirans Studied by UV and 13C NMR Spectra
Authors: Smolinski Stefan , Balazy Michal , Iwamura Hiizu , Sugawara Tadashi , Kawada Yuzo , Iwamura Michiko 
Published: July 2006

Abstract
UV and 13C NMR spectra of spirocyclic orthocarbonates, a spirobi(benzodithiepin) and a spirobi(naphthopyran) have been measured and compared with those of the “half compounds” to see the spiroconjugation effect. Whereas batho- and hyperchromic shifts are usually brought about by spiroconjugation, hypso- and hypochromic effects have been observed for 2,2′-spirobi[1,3-benzodioxole]. Through-bond interaction similar to the mechanism for the anomeric effect is considered to be operative in attenuating the electron release from the orthocarbonate moiety to the benzene chromophore. The downfield shifts of 20–25 and ca. 40 ppm were noted for the spirocarbons of the conformationally flexible and rigid orthocarbonates, respectively, as compared to the corresponding methylene carbons of the half compounds. The largest paramagnetic shift of 66.3 ppm is observed for the orthothiocarbonate and attributed to the presence of the low-lying d-orbitals due to through-space interaction of the four sulfur atoms.
Photocycloadditions of Benzophenone with 6-Methylenetricyclo[3.2.1.02,7]oct-3-en-8-one and Its Related Compounds. Di-π-methane Photorearrangement of the Primary Photocycloadducts
Authors: Nitta Makoto , Sugiyama Hiroshi 
Published: July 2006

Abstract
The photocycloadditions of benzophenone with constrained divinylcyclopropanes such as 1,5-dimethyl- and 1,3,5-trimethyl-6-methylenetricyclo[3.2.1.02,7]oct-3-en-8-ones, 5,8-dimethyl-9-methylenetricyclo[3.3.1.2,8] non-3-en-6-one, 5,8-dimethyl-9-methylenetricyclo[3.3.1.02,8]non-3-en-7-one, and their corresponding alcohols were investigated. In no cases, was oxetane formation observed but the formal [2+6] cycloaddition which originates from the cleavage of a cyclopropane ring was observed. In the case of the compounds which have a carbonyl function, benzophenone sensitized di-π-methane or oxadi-π-methane rearrangement of the primary photocycloadducts was observed. The mechanism of the formation of photoproducts is discussed with emphasis on (i) the nature of the intermediates having tricyclo[3.2.1.02,7]oct-3-en-6-yl and tricyclo[3.3.1.02,8]non-3-en-9-yl radicals, (ii) the regioselectivity of the di-π-methane or oxadi-π-methane rearrangement of the primary photocycloadducts.
A Dimethyl Sulfoxide-mediated Oxidation of Arylalkyl and Alkyl Alcohols to Corresponding Aldehydes and Ketones via Tropolonyl Ethers
Authors: Takeshita Hitoshi , Mametsuka Hiroaki , Matsuo Norihide 
Published: July 2006

Abstract
The arylmethyl and diarylmethyl ethers of tropolones were oxidized to the corresponding carbonyl derivatives by heating in dimethyl sulfoxide. The free alcohols were oxidized at a much slower rate, suggesting that some sort of DMSO-linked intermediates are responsible for the oxidation. Inertness of free alcohols was proven by means of the cross-over experiments, including deuterium-labelling. This oxidation was applicable to alkyl ethers, but not to alkenyl ethers, which are known to cause the Claisen-rearrangement.
The Cycloisomerization Reaction of [2.2]Metacyclophanes to 1,2,3,3a,4,5-Hexahydropyrenes. Substituent Effects and Directional Selectivity
Authors: Yamagishi Takeshi , Torizuka Koichi , Sato Takeo 
Published: July 2006

Abstract
Substituent effects and directional selectivity in iodine-induced cycloisomerization reaction of [2.2]metacyclophane were tested using several derivatives of the latter. The reaction was found to be highly selective, and electron-donating groups gave a hexahydropyrene preserving a substituted aryl ring. On the other hand, an alkyl group ortho to the bridge gave a hexahydropyrene with a hydrogenated substituted ring.
The Total Synthesis of Antibiotic Fortimicin B
Authors: Honda Yutaka , Suami Tetsuo 
Published: July 2006

Abstract
The total synthesis of antibiotic fortimicin B (1b) is described. The sugar component of 1b: 6-epi-purpurosamine B was converted to the sugar chloride: 2,6-bis(2,4-dinitrophenylamino)-2,3,4,6,7-pentadeoxy-β-l-lyxo-heptopyranosyl chloride (5). The aminocyclitol component of 1b: fortamine B was also converted to the partially protected aglycone (9). The condensation of aglycone 9 with the sugar chloride 5 gave the desired condensation product in 37% yield. The analogous condensation of the Dl-form of the aglycone with 5 afforded the same condensation product in 19% yield, it was then converted to 1b by step-by-step hydrolysis.