bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic Studies of Bacitracin. III. Synthesis of (S)-2-(2-Methylbutyryl)-thiazole-4-carboxylic Acid and Its Peptide Derivative
Authors: Ariyoshi Yasuo , Shiba Tetsuo , Kaneko Takeo 
Published: July 2006

Abstract
An optical active 2-(2-methylbutyryl)thiazole-4-carboxylic acid obtained from bacitracin F by an acid hydrolysis was synthesized starting from l-isoleucine. Applying the usual methods for the peptide synthesis, 2-(2-methylbutyryl)thiazole-4-carbonyl-l-leucyl-d-glutamic acid α-methyl-γ-t-butyl ester corresponding to the N-terminal tetrapeptide of bacitracin F, was then synthesized from the thiazole carboxylic acid. UV spectrum of the synthetic tetrapeptide was very similar to that of bacitracin F.
The Ionic Telomerization of Conjugated Diene Compounds. III. The Effects of the Addition of Lewis Bases on the Cationic Telomerization of Butadiene with Its Hydrochlorides
Authors: Asahara Teruzo , Kise Hideo 
Published: July 2006

Abstract
The effects of the addition of several oxygen- and nitrogen-containing compounds on the cationic telomerizations of butadiene with its hydrochloride were investigated. The addition of both acetonitrile and ethyl ether to an ethyl bromide solution of ferric chloride or a methylene chloride solution of titanium tetrachloride resulted in large decreases in the catalytic activities of the solutions at low temperatures. On the other hand, the addition of nitroethane to an ethyl bromide solution of aluminum chloride increased the activity of the catalyst, although the addition of nitrobenzene decreased it. The addition of ethyl ether to ferric chloride or titanium tetrachloride led to the formation of telomers with lower molecular weights and larger degrees of unsaturation, whereas a nitroethane - aluminum chloride catalyst gave telomers with higher molecular weights. The monomolecular addition complexes of several Lewis acids and Lewis bases were isolated, and the catalytic abilities of the complexes in halogenated hydrocarbons were investigated. The structures of the higher telomers were analyzed and will be discussed.
ESR Studies of the Alkali Metal-Acenaphthene Ion Pairs
Authors: Iwaizumi Masamoto , Suzuki Masayasu , Isobe Taro , Azumi Hiroshi 
Published: July 2006

Abstract
Ion pairs formed by alkali metals with acenaphthene in ether-type solvents have been investigated by means of electron spin resonance (ESR). The ESR spectra of the ion pairs were found to show phenomena quite analogous to those found by de Boer et al. in the pyracene-alkali ion system; similar two-line-width alternation effects were also observed in the present work. These observations were contrary to the expectations formed by a consideration of the pyracenealkali metal ion pair, where the phenomena have been explained on the basis of the assumption that a potential well exists near the two ethylene bridges. This paper shows that, in the acenaphthene-alkali metal ion pairs, the alkali ion may be situated above the naphthalene skeleton rather than near the ethylene bridge. One of the line-width alternation effects is explained in terms of the exchange reaction between two ion-pair conformations in which the alkali ion is situated above and under the molecular plane respectively, while the other is ascribed to the oscillation of the cation in the potential well above either side of the molecular plane.
The Radiation Chemistry of Cyclic Dienes. III. The Effects of Electric Fields and Additives in the Radiolysis of 1,4-Cyclohexadiene Vapor
Authors: Nakagawa Tsunehiko , Takamuku Setsuo , Sakurai Hiroshi 
Published: July 2006

Abstract
In the γ-radiolysis of 1,4-cyclohexadiene vapor at room temperature, the contribution of neutral and ionic intermediates to the main products has been investigated by the application of electric fields and by the addition of nitrous oxide and ammonia as an electron and an ion scavenger respectively. It was suggested that the precursors of hydrogen, acetylene and 1,3-butadiene are exclusively the neutral excited molecules of 1,4-cyclohexadiene directly produced by the γ-irradiation, while those of the C6 products and polymer are mostly the ionic species. It was further derived that the contribution of neutralization reaction has little importance in the formation of hydrogen, acetylene and 1, 3-butadiene.
Hot Atom Chemistry of Phenylphosphorus Compounds
Authors: Kiso Yoshiyuki , Kobayashi Mitsue , Kitaoka Yoshinori , Kawamoto Keizo , Takada Jitsuya 
Published: July 2006

Abstract
A series of phenylphosphorus compounds, such as triphenylphosphine, triphenylphosphine oxide, triphenylphosphite, diphenylphosphite, tricresylphosphite, monophenylphosphate, triphenylphosphate, phenylphosphonic acid and phenylphosphonous acid, were irradiated in a nuclear reactor for 15–2100 min with a thermal neutron flux of 5×1012 n/cm2/sec. The relative amounts of the 32P-labeled gaseous products and the products soluble in an aqueous solution in the irradiated samples were then estimated. It was found that the compounds containing an oxygen atom bonded as P=O in a molecule had a tendency to yield the higher percentages of the products which were nonvolatile and soluble in an aqueous solution. The recoil products were separated into components by paper chromatography, and the chemical form of each component was identified. It was shown that the number of recoil products separated and the distribution of the chemical forms were greatly influenced by the chemical forms of the target compounds. The chemical reactions of the recoil 32P atom are also discussed, and a mechanism of the reactions which fits the experimental results is proposed.
Some Remarks on the Extended Hückel Approximation in the Independent-Electron MO Theory
Authors: Fukui Kenichi , Fujimoto Hiroshi 
Published: July 2006

Abstract
The sum of one-electron energies in the extended Hückel MO theory has been related to the total energy in the LCAO SCF MO theory including electron repulsion and nuclear repulsion terms. The sum of one-electron energies in the extended Hückel MO theory can be divided into the two parts; one almost independent of nuclear configuration and one highly sensitive to the configurational change. Of these the latter is found to be responsible for the stabilization energy due to the bond formation. The role of the highest occupied MO and the lowest unoccupied MO toward chemical reaction has been also discussed in the framework of the extended Hückel calculations. The partial AO population in these particular MO’s is shown to be almost valence-inactive one, being ready to be mobilized in case of chemical interaction with other systems.
A Simple Hückel Treatment of the Energy of Excimer Luminescence
Authors: Azumi Tohru , Azumi Hiroshi 
Published: July 2006

Abstract
The energy of the excimer luminescence is interpreted in terms of a simple Hückel-type dimer orbitals, which are constructed by treating the excimer as one species. The present model of the excimer yields results quite similar to those of the complicated ASMO CI treatment as developed earlier; further, it is capable of explaining various characteristics of the excimer, including the 6000 cm−1 rule.
The Synergistic Effect in Solvent Extraction—The Correlation of the Ionic Radius of Rare Earth Elements with the Stability Constants of Rare Earth Benzoyltrifluoroacetonate Adducts with n-Hexyl Alcohol, TBP and TOPO
Authors: Shigematsu Tsunenobu , Tabushi Masayuki , Matsui Masakazu , Honjyo Takaharu 
Published: July 2006

Abstract
The synergistic effects of n-hexyl alcohol, TBP and TOPO on the extraction of rare earth ions with benzoyltrifluoroacetone in benzene have been studied. The stability constants of the adducts were determined by means of the curve-fitting method. The equation based on the shift of pH1⁄2 (−ΔpH1⁄2) was also employed to analyse the data. The results were discussed in relation to the ionic radius of rare earth elements and summarized as follows: (1) The stability of rare earth benzoyltrifluoroacetonate decreases but that of the adducts increases, as the ionic radius increases. (2) The maximum number of base molecules bonding to one molecule of the metal chelate is 2, except that in the case of lutetium adduct with TOPO, where the formation of secondary adducts is not observed. (3) Although the overall stability constant of the adduct increases in the following order; lutetium &lt; terbium &lt; europium &lt; lanthanum, as mentioned above, the first stability constant does not show such a distinct sequence. Therefore the contribution of the second stability constant seems to be an important factor. (4) Organic bases studied form stable adducts with rare earth benzoyltrifluoroacetonates in the following order; n-hexyl alcohol&lt;TBP&lt;TOPO. This order corresponds to the donating power of lone pair electrons of the oxygen atoms in these compounds.
Soluble Collagen of Chicken Leg Tendon; Its Denaturation Temperature and Hydrodynamic Properties
Authors: Sakai Rume , Ikeda Shoichi , Isemura Toshizo 
Published: July 2006

Abstract
The soluble collagen was extracted from chicken leg tendon with a 0.15 m citrate buffer at pH 3.8. The denaturation temperature was estimated to be 38°C by measuring the intrinsic viscosity and also by measuring the optical rotation at 589 mμ. The optical rotatory dispersion constants (λc) of collagen and gelatin were found to be 210±10 and 220±10mμ respectively. The intrinsic viscosity of collagen was 12.5±1.0 dl/g. The rotational diffusion coefficient at 20°C in water was 795±75 sec−1. The sedimentation constant at 20°C in water was 3.0S. From these data, the size and molecular weight of collagen were discussed. The collagen of chicken leg tendon is 2900 to 3000 Å in length and 12 to 16 Å in diameter, and has a molecular weight of 34×104.
Studies on Polymers from Cyclic Dienes. VI. Radiation Polymerization of the Thiourea Complex of Cyclopentadiene
Authors: Aso Chuji , Kunitake Toyoki , Ishimoto Yoshikazu 
Published: July 2006

Abstract
Cyclopentadiene was found to polymerize as its thiourea complex when irradiated with γ-rays from 60Co. The conditions of preparing the complex were an important factor in increasing the conversion, the use of 50 vol% aqueous acetone giving the best results. The polymer yield increased with dose and with temperature. The apparent activation energy of the polymerization was 2.7 kcal/mol. The poly cyclopentadiene thus obtained was concluded from its NMR and IR spectral data to have mainly the 1,4-structure.
Rheological Properties of Hydrogels of Agar-agar. II. Stress Relaxation of Concentrated Hydrogels
Authors: Watase Mineo , Arakawa Kiyoshi 
Published: July 2006

Abstract
A stress-relaxation experiment on hydrogels of agar-agar has been made over the range of concentration of about 3—11% by weight. A chainomatic balance relaxometer was used for the measurement of the relaxation Young’s modulus, and the temperature was varied over the range of about 20—70°C. The obtained relaxation curves have been analyzed using a mechanical model composed of three parallel Maxwell models. The relaxation times obtained for the gels of different concentrations at the same temperature have been found to be independent of the concentration. The elastic Young’s modulus, which may be attributed to the main network structure in the gels, has been found to be proportional to the 1.8 power of concentration. From the temperature dependence of the longest relaxation time, the activation energy for the relaxation process attributed to the destruction of junctions in the main network structure has been determined to be about 5 kcal/mol, irrespective of the concentration, over the whole range; this is of the order of the activation energy for the hydrogen bonds.
Effect of Molecular Vibrations on Gas Electron Diffraction. I. Probability Distribution Function and Molecular Intensity for Diatomic Molecules
Authors: Kuchitsu Kozo 
Published: July 2006

Abstract
General expressions and their practical approximations are presented for the molecular intensity of gas electron diffraction and the radial distribution function for an atom pair in the molecule which exerts moderately anharmonic intramolecular motion in thermal equilibrium. The calculations are based on a polynomial expansion of the probability distribution function of the internuclear distance around a Gaussian function representing harmonic vibration. The coefficients of the expansion for a diatomic system are calculated by the second-order perturbation method in terms of the coefficients of the potential energy expanded to the fourth order of the displacement in the internuclear distance. The structural parameters under various definitions (the mean internuclear distances, the mean square amplitudes, and the phase parameters) of a number of diatomic molecules are tabulated by the use of the spectroscopic values ωe, αe, and χe taken from the literature. The temperature dependence of the structural parameters is discussed.
The Crystal Structure of Bis(pyridine-2-carboxamido)nickel(II) Dihydrate
Authors: Nawata Yoshiharu , Iwasaki Hitoshi , Saito Yoshihiko 
Published: July 2006

Abstract
The orange-red, diamagnetic crystals of [Ni(pia)2]·2H2O (piaH: pyridine-2-carboxamide) have been subjected to X-ray crystallographic analysis. They are orthorhombic, space group Pm21b-C2v2, with two formula units in a cell of dimensions: a=7.61, b=20.19 and c=4.46 Å. The crystals consist of planar molecules in which Ni(II) exhibits a square planar coordination and the two ligands are coordinated to the central nickel atom with four nitrogen atoms in trans-configuration. The molecules are tilted about 40° with respect to the plane (001), and are piled up above one another along the c-axis to form columns. These columns are linked with each other by intermolecular hydrogen bonds of N–H···O type, thus forming layers parallel to the plane (010). The layers are piled up along the b-axis by way of two water molecules which are hydrogen-bonded to the oxygen atoms of the amide groups. There exist stacking faults along this direction.
Semi-Empirical SCF Molecular Orbital Treatment for Valence Electron Systems. I. Small Molecules
Authors: Yonezawa Teijiro , Yamaguchi Kaichiro , Kato Hiroshi 
Published: July 2006

Abstract
A semi-empirical SCF method for valence electron systems is presented. In the present method, the one-center integrals are estimated by means of the empirical values, while the two-center Coulomb integrals are calculated by the Ohno approximation. The other electronic repulsion integrals are evaluated by the Mulliken approximation. All overlap integrals in the secular equation are taken into account. By the present method, the electronic structures of several small polyatomic molecules are then studied. The calculated results are compared with the full SCF calculations and with the experimental values. The agreements between them are almost entirely satisfactory. The limitations of this method and the values of the parameters used are also discussed briefly.
Tracer Study of the Reactivity of Hydrogen Adsorbed on Nickel in the Hydrogenation Reaction
Authors: Takeuchi Toyosaburo , Miyatani Daisaku 
Published: July 2006

Abstract
The correlation between the bond strength of adsorbed hydrogen and the reactivity of the hydrogen toward ethylene has been investigated by using tritium as a tracer. Hydrogen (or tritium) was adsorbed first on powdered nickel at −78°C; tritium (or hydrogen) was subsequently adsorbed, and then ethylene was added. The total coverage of hydrogen in every experiment was 0.16 or 0.4 for the nickel reduced at 200°C, and 0.06 or 0.4 for the nickel reduced at 400°C. After a certain time, the hydrogen and the mixture of ethane and ethylene were drawn off successively from the reaction vessel and separated. An assay of the tritium in each fraction of the gas was then made. The results on the nickel reduced at 200°C indicate that neither the very-strongly-adsorbed hydrogen nor the weakly-adsorbed hydrogen reacts with ethylene. The results on the nickel reduced at 400°C indicate that the weakly-adsorbed hydrogen does not react with ethylene either. These findings suggest that the very strong sites for the adsorption of hydrogen, which are inactive in the hydrogenation, are diminished by the elevation of the reduction temperature.
The Oxidation of α-Methylstyrene in the Presence of Benzaldehyde
Authors: Niki Etsuo , Kamiya Yoshio 
Published: July 2006

Abstract
The oxidation of α-methylstyrene in the presence of benzaldehyde was studied at 40°C, with and without added metal salt catalysts, from the viewpoint of the products obtained. The products were α-methylstyrene oxide, acetophenone, formaldehyde, α-methylstyrene polyperoxide, perbenzoic acid, and benzoic acid; few side reactions between these products were observed under the reaction conditions employed here. Emphasis was laid on the effect of metal salt catalysts and of the initial composition of the oxidants on the cleavage products from α-methylstyrene. Manganese and copper salts were found to have little effect, while cobalt salt showed a characteristic effect on the formation of the cleavage products. In the presence of cobalt salt, the formation of acetophenone was accelerated. The increase in the formation of α-methylstyrene oxide in this system compared with the oxidation of α-methylstyrene alone may well be attributed to the polar reaction of α-methylstyrene with perbenzoic acid formed from benzaldehyde. The consumption of perbenzoic acid in various systems was also examined. The increase in the initial concentration of benzaldehyde increased the yield of α-methylstyrene oxide and decreased that of acetophenone.
Asymmetric Synthesis with Sugar Derivatives. II. Asymmetric Syntheses by Methoxy-Mercuration of Cinnamic Esters of Sugar Derivatives
Authors: Kawana Masajiro , Emoto Sakae 
Published: July 2006

Abstract
The methoxy-mercurations of cinnamic esters of 1, 2; 5, 6-di-O-isopropylidene- and -cyclohexylidene-d-glucose, 5-deoxy-1, 2-O-isopropylidene-d-xylose, (−)-menthol, and (+)-borneol with mercuric acetate in methanol, followed by the reductive demercuration of the 3-acetoxymercuri-2-methoxyhydrocinnamic esters with sodium borohydride, gave, after the hydrolysis of the demercurated esters, IV, with alkali, 3-methoxy-3-phenylpropionic acid (V) in 1—27% optical yields, depending on the methoxy-mercuration time. When the methoxy-mercuration time was extended, the specific rotation of V decreased, but there was no corresponding decrease in the synthetic yield in the presence of nitric acid as a catalyst. This shows that an equilibrium in the methoxy-mercuration has been completed. The demercurated esters, IV, were reduced with lithium aluminum hydride to afford 3-methoxy-3-phenylpropan-1-ol (IX) in 6—22% optical yields. The absolute configurations of both V and IX were established to be (S)(−)-configurations. In the methoxy-mercuration, it seems likely that no oxygen atoms of sugar derivatives act as a co-ordinating group to keep the acetoxymercuri-group onto one side of the carbon-carbon double bond of cinnamate.
The Effect of Substituents in Radical Reactions: Reactivities of Substituted Cumenes to Attack by the Polystyryl Radical
Authors: Yamamoto Tadahiro 
Published: July 2006

Abstract
The polymerizations of styrene in a series of nuclear-substituted cumenes, using α, α′-azobisisobutyronitrile as an initiator, have been carried out at 60°C, and the chain transfer constants, Cs, for the substituted cumenes have been determined. It has been found that the Cs values for cumenes with electron-repelling groups are smaller than that for an unsubstituted cumene, while those for cumenes with electron-attracting groups are greater. The plot of log (k⁄k0) against the corresponding Hammett’s σ-constants failed to give a linear relationship. The modified Hammett’s equation including the resonance effect for radical reactions, the equation which was proposed by the author and Azumi, i.e.,: log(k⁄k0)=ρσ+γER, could be adopted to the transfer with the usual precision, giving γ=1 and ρ=0.7. It is considered that the effects of substituents on the transfer reactivities of cumenes to the attack of the polystyryl radical depend on the contributions of polar and resonance factors.
The Synthesis and the Thermal Decomposition of 1, 3, 4-Dioxazole Derivatives
Authors: Nohira Hiroyuki , Inoue Kenji , Hattori Hirotoki , Okawa Toji , Mukaiyama Teruaki 
Published: July 2006

Abstract
2, 2, 5-Tri-substituted-1, 3, 4-dioxazoles have been prepared by the reactions of benzhydroxamic acids with the diethylketals of such ketones as acetone, cyclohexanone, acetophenone and benzophenone. These dioxazoles decompose at elevated temperatures (above 150°C) into phenylisocyanates and ketones. A kinetic study of the decomposition reaction in nitrobenzene has been attempted, and the first-order rate constants have been obtained.
Kinetische Untersuchung über die durch Triphenylmethyl induzierte Zersetzung von Benzoylperoxyden
Authors: Suehiro Tadashi , Kanoya Akio , Hara Humihiro , Nakahama Tetsuro , Omori Muneki , Komori Tsuneo 
Published: July 2006

Abstract
Die Geschwindigkeiten der Umsetzung von m, m′- und p, p′-symmetrisch substituierten Benzoylperoxyden mit Triphenylmethyl in aromatischen Lösungsmitteln wurden durch Messung der Abnahme der Absorption vom Triphenylmethyl bei 15–35°C bestimmt. Die Umsetzung von Peroxyd in Benzol wird durch die Elektron Acceptor Substituenten beschleunigt (rho=+1.45, r=0.975) und die isokinetische Temperatur ist ca. 180°K. Die Reaktionsgeschwindigkeit von Peroxyd mit Triphenylmethyl wird wieder durch die Polarität der aromatischen Lösungsmitteln beschleunigt und bei dem nicht substituierten Benzoylperoxyd erhält man die isokinetische Temperatur von ca. 390°K. Daraus. wird geschlossen, dass im Übergangszustand polaren Strukturen eine grosse Rolle spielen.
An X-ray Study on the Phase Transition of Phenanthrene Crystal
Authors: Matsumoto Shoichi , Fukuda Tsuguo 
Published: July 2006

Abstract
The presence of a higher-order phase transition at around 60–70°C in phenanthrene crystal, previously suggested by the anomalies in electrical conductivity and in thermal expansion, and by the endothermic phenomenon, has been confirmed through an X-ray powder diffraction study. The results disclose the following facts: (1) the phenomena of the transition begin about 45°C and gradually become remarkable with a rise in the temperature, until the phenomena practically cease to occur at 68–69°C; (2) the lattice constants for the monoclinic cell increase conspicuously in the temperature range from about 50°C to 68°C, while both the crystal system, which is monoclinic, and the space group, P21, remain unaltered on passing through the transition temperature, and (3) the unit cell dimensions of the high-temperature modification determined at 80°C are: a=8.54, b=6.25, c=9.55 Å and β=99.0°.
Oxidative Polymerization of Polybutadiene and Its Derivatives
Authors: Chen Leo-Wang , Nemoto Tsuguo , Kumanotani Ju 
Published: July 2006

Abstract
The oxidative polymerization or peroxide curing for such prepolymers as polybutadiene consisting mainly of 1, 2-structure, or esters containing the butadiene units was studied by means of infrared spectral analysis and dynamic mechanical measurements. Films of the cross-linked polybutadiene formed by the oxidative polymerization reaction show a high glass transition temperature and a high degree of crosslinking. This is considered to be the result of the larger amount of double bonds that are involved in the prepolymers and which suffer cross-linking, and the result of the presence of such polar groups as those of carboxyl, carbonyl and hydroxyl groups in the dried film, which are formed in the course of oxidative polymerization. When t-butylperbenzoate was used as a catalyst for cross-linking polybutadiene, some cyclization of vinyl groups was observed, leading to a less effective cross-linking. A greater reactivity was observed for trans-ethylenic double bonds than for vinyl groups in these reactions. Polybutadiene, being of larger molecular weight, gave a film of a higher (Tg)d value.