bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Ultraviolet Ray on Graphite Fluoride in Organic Solvents
Authors: Watanabe Nobuatsu , Ueno Kazuo 
Published: July 2006

Abstract
Graphite fluoride, (CF)n, was photolyzed in alcohols and hydrocarbons. Hydrogen fluoride was formed in each case. Alcohols were partially converted into the corresponding carbonyl compounds by the reaction 2(C–F)+RR′CHOH\oversethν→2(C)+2HF+RR′C=O. ESCA measurement revealed that the fluorine at the surface decreases more rapidly than that of the inner region of (CF)n particle, the inner region being also photolyzed. Results of DTA measurement indicate that the irradiation reduces the thermostability of (CF)n.
Friedel-Crafts Reaction of Aromatics with Epoxides. Stereochemistry and Selectivities
Authors: Inoue Masashi , Chano Keizo , Itoh Osamu , Sugita Toshio , Ichikawa Katsuhiko 
Published: July 2006

Abstract
The Friedel-Crafts reaction of toluene and anisole with 2-methyloxirane and 2,3-dimethyloxiranes was examined. The inter- and intramolecular selectivities of 2-methyloxirane were between those of conventional methylation and isopropylation. It was also found that all the positional isomers formed by the aluminum chloridecatalyzed reaction of toluene and anisole had almost completely inverted configurations of the epoxide carbons. These results are explained by a mechanism of the SN2 type. Diminished stereospecificities were observed in aluminum bromide-catalyzed reactions.
Synthesis of l-Epicapreomycidine
Authors: Teshima Tadashi , Konishi Kunikazu , Shiba Tetsuo 
Published: July 2006

Abstract
A cyclic guanidino amino acid, l-epicapreomycidine, isolated from hydrolyzates of protease inhibitors such as chymostatin and elastatinal was synthesized. This amino acid is a diastereomer of l-capreomycidine which is a component amino acid of tuberactinomycin N,O and capreomycin. A new synthetic route from β-hydroxy-Dl-orni thine via an aziridine compound to Dl-capreomycidine was applied to the synthesis of l-epicapreomycidine starting from erythro-β-hydroxy-l-ornithine. A convenient and one-step technique to obtain l-erythro form from a mixture of four diastereomers of β-hydroxyornithine by means of enzymatic reaction was newly exploited. The synthetic l-epicapreomycidine obtained was identical with natural one in all respects, thus confirming the proposed structure.
Aromatization of Ring-A in α-Bromocholestan-6-ones
Authors: Shafiullah  , Islamuddin  
Published: July 2006

Abstract
Pyridine promoted dehydrohalogenation of β-chloro-5-bromo-5α-cholestan-6-one resulting in ring-A aromatization with expulsion of C-10 angular methyl group to give 19-norcholesta-1,3,5(10)-trien-6-one along with 3a,5-cyclo-5α-cholest-7-en-6-one, cholesta-2,4-dien-6-one, and 5α-cholestane-3,6-dione. Similar treatment of 3β-chloro-5,7β-dibromo-5α-cholestan-6-one ends up with the aromatization of ring-A with migration of C-10 angular methyl group to give 1-methyl-19-norcholesta-1,3,5(10)-trien-6-one.
INDO Molecular Orbital Interpretation of Thermal Singlet Oxygen-complex Generation by Strained Acetylenes
Authors: Ohkubo Katsutoshi , Sato Hiroyuki 
Published: July 2006

Abstract
A three-center interaction between the (πu)y of strained XC≡CX (X=H,F, or OCH3) and the (πg)y of 3O2 separated the two half-occupied πg MOs of 3O2 on an energy scale of 428–494 kJ/mol causing spin inversion in 3O2. A perepoxide-type 1O2–XC≡CX intermediate once formed is transformed into a stable dioxetene-type 1O2 complex from which the free generation of 2O2 was found to be difficult.
The Mössbauer Effect of 119Sn in the Dimethylbis(8-quinolinolato)tin(IV) Single Crystal
Authors: Negita Hisao , Boku Ryukei , Ichiba Sumio 
Published: July 2006

Abstract
The Mössbauer absorption spectrum of 119Sn in the single crystal of dimethylbis(8-quinolinolato)tin(IV) was studied by an intensity-tensor method. The orientation of the principal axes of the electric-field gradient (EFG) was discussed from the point of view of point-charge formalism.
Kinetics of Dissociation of the Hydrogen Bond in the (n,π*) Singlet State of 9,10-Diazaphenanthrene
Authors: Yamazaki Iwao , Takeda Hiroyuki , Baba Hiroaki 
Published: July 2006

Abstract
Changes of fluorescence properties with temperature have been examined for 9,10-diazaphenanthrene (DAP) in proton-donating solvents. From a kinetic analysis, the rate constant for dissociation of the hydrogen bond in the (n,π*) singlet state of DAP is evaluated to be 4.3×108 s−1 at 113 K, and the activation energy of the dissociation is 10.0 kJ/mol.
Formation of Five-coordinate Ni(II) Complexes with 2,12-Dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene Analogs and Halide Ions in Nitromethane
Authors: Mochizuki Katsura , Ito Tasuku , Fujimoto Masatoshi 
Published: July 2006

Abstract
Formation of 5-coordinate Ni(II) complexes of the title quadridentate ligands and halide ions (Cl−, Br−, and I−) in nitromethane was investigated. Some of the formation constants were estimated by means of curve-fitting method.
Effect of Plasticizer on the Selectivity of Potassium-selective PVC Membrane Electrodes Based on Bis(crown ether)s
Authors: Tamura Hiroshi , Kimura Keiichi , Shono Toshiyuki 
Published: July 2006

Abstract
Potassium-selective PVC membrane electrodes based on bis(crown ether)s containing benzo-15-crown-5 moiety were prepared, o-nitrophenyl octyl ether (NPOE) or dipentyl phthalate (DPP) being used as a plasticizer. Selectivity coefficients for various monovalent ions were measured. The preference of potassium over sodium in the bis(crown ether) (I; n=5)–NPOE electrode system is close to that in the valinomycin system.
Synthesis and Magnetism of MIICuII3-type Tetranuclear Complexes, the Nickel(II) and the Cobalt(II) Complexes with N,N′-Bis(aminoalkyl)oxamidatocopper(II)
Authors: Okawa Hisashi , Kawahara Yukitaka , Mikuriya Masahiro , Kida Sigeo 
Published: July 2006

Abstract
Hetero-metal tetranuclear complexes, [N,N′-bis(aminoalkyl)oxamidatocopper(II)]cobalt(II) and tris[N, N′-bis(aminoalkyl)oxamidatocopper(II)]nickel(II) perchlorate (or nitrate), were synthesized and characterized. Gryomagnetic investigation demonstrated that a considerably strong antiferromagnetic spin-exchange interaction is operating between copper(II) and cobalt(II) or nickel(II) ions.
Infrared Spectra and Intramolecular Hydrogen Bonding of p-(Substituted phenoxy)-α-(dialkylamino)acetanilides
Authors: Abe Kazuhisa , Hirota Minoru , Sugiura Michiharu , Hamada Yoshiki 
Published: July 2006

Abstract
The title compounds were synthesized with pharmaceutical interests, and their infrared spectra in the NH and carbonyl stretching regions were measured. By comparing the spectra with those of p-phenoxyacetanilide, intramolecular hydrogen bonds are shown to exist between the amide NH and the α-dialkylamino groups.
Gas Chromatography under the Column Outlet Pressure Higher than Atmospheric
Authors: Takeuchi Koji , Ohzeki Kunio , Kambara Tomihito 
Published: July 2006

Abstract
The effects of column outlet pressures on the HETP vs. carrier gas velocity curves are discussed on the basis of KOS theory. It is shown that when a column is operated at a constant outlet pressure higher than atmospheric the minimum of H-\baru curve shifts towards lower HETP and \baru values, and on the contrary the operation at reduced outlet pressure results in the shift of the minimum towards higher HETP and \baru values. The separation factor and number of theoretical plates obtained by a column operated at the outlet pressure of 4.0 atm are superior by ca. 10% to those obtained by normal gas chromatography.
Base-catalyzed Autoxidation of Fluorene in the Presence of Phase Transfer Catalysts
Authors: Yamashita Junzo , Ishikawa Shinji , Hashimoto Harukichi 
Published: July 2006

Abstract
Base-catalyzed autoxidation of fluorene to fluorenone has been carried out in an aqueous potassium hydroxide–benzene two-phase system in the presence of 18-crown-6 as a phase transfer catalyst. The initial rate of oxidation is proportional to the amount of fluorene. The addition of 18-crown-6 leads to the increased concentration of potassium hydroxide and water in the benzene phase, which is responsible for the increased rate of oxidation. Increasing the concentration of potassium hydroxide in the aqueous phase increases the concentration of 18-crown-6 and potassium hydroxide in benzene, resulting in a large increase in the rate of oxidation. The ease of oxidation with respect to the base is KOH&gt;NaOH&gt;LiOH&gt;Ba(OH)2. Less polar solvents such as cyclohexane used as an organic phase decrease the oxidation rate.
Structural Aspects of Catalytic Activities of Thiazolium Salts in Benzoin Condensation Reaction in Methanol
Authors: Yano Yumihiko , Tamura Yoshiharu , Tagaki Waichiro 
Published: July 2006

Abstract
The rates of benzoin condensation catalyzed by thiazolium salts of varying structures have been determined in methanol containing triethylamine as the base by the method of gas chromatography. The condensation activity was observed not to be linearly correlated with the acidities of 2-position of catalyst thiazolium ring. The dimethylamino substituent was found not to act as an internal base for benzoin condensation, but rather exerted an inhibitory effect. In general, the effects of N-substituent on the rate of benzoin condensation were small. However, a large steric hindrance was observed for 3-methyl-4-menthylthiazolium perchlorate.
Photocycloaddition Reaction of Alkyl-substituted 1,4-Naphthoquinones with Olefins. Substituent Effects on Controlling the Orientation of Cycloaddition Reaction
Authors: Maruyama Kazuhiro , Narita Noritsugu 
Published: July 2006

Abstract
Photolysis of a benzene solution of 2-alkyl- or 2,3-dialkyl-substituted 1,4-naphthoquinone mixed with an arylsubstituted ethylene afforded 3,4-benzobicyclo[4.2.0]octene-2,5-dione derivatives (cyclobutane type adducts) in a good yield without any other types of products. The orientation of the cycloaddition was likely to control by the adverse van der Waals repulsion of the substituents of the quinone and olefin in addition to the electronic effects of the substituents. The predominant factor orientating the cycloaddition seems to play the van der Waals repulsion due to the substituents both of quinone and olefin.
Carbon–Carbon Bond Formation by the Use of Chloroiodomethane as a C1 Unit. II. The Preparation and Synthetic Application of 1-Chloro-3-iodoheptane
Authors: Miyano Sotaro , Hokari Hiroshi , Umeda Yoshiharu , Hashimoto Harukichi 
Published: July 2006

Abstract
Terminal alkenes, R–CH=CH2 (R=Et, n-Pr, n-Bu, n-Hex), were readily transformed into 1-chloro-3-iodoalkanes by the AIBN-induced free radical addition of chloroiodomethane. Thus, 1-chloro-3-iodoheptane was obtained from 1-hexene in an 88% yield; this in turn was allowed to react with dialkyl malonates in the presence of alkoxides in alcohols to give dialkyl 2-butylcyclobutane-1,1-dicarboxylates and dialkyl (E)-3-octene-1,1-dicarboxylates (7), either of which could be obtained preferentially by the choice of the experimental parameters. The olefinic product, 7, was further utilized for the synthesis of (E)-5-decenyl acetate and/or 1,4-nonanolide.
Kinetics of the Gas-phase Photochlorination of Dichloromethane in a Tubular Photoreactort
Authors: Sugawara Takuo , Suzuki Makoto , Ohashi Hiroyasu 
Published: July 2006

Abstract
The gas-phase photochlorination of dichloromethane was conducted at a low extent of conversion from 9 °C to 100 °C in a tubular flow reactor irradiated by means of a circular array of low-pressure mercury lamps. The kinetics were studied with due consideration taken of the radial variation in light intensity across the reactor and with the proper selection of kinetic equations, including the recombination of dichloromethyl radicals as the dominant termination step. The dependence of the absorbed radiant energy on the chlorine concentration was well simulated by the use of the radial-light and line-source model. The predominance of the observed production rate of hydrogen chloride over that of chloroform was also reproduced well by the appropriately selected kinetic expressions, without any use of the long-chain approximation. The recombination rate constant of dichloromethyl radicals was determined to be 1013.5 cm3 mol−1 s−1; this is larger than the previously reported value by the factor of 12.6, and is in fair agreement with the theoretical value, 1013.3−13.4, calculated from the statistical factor, and with the collision rate constant based on the hard-sphere model.
Thermal Diffusion Measurements of Symmetric Tetraalkylammonium Bromides in Water
Authors: Yogi Zen’ei , Kitano Hiroshi , Toma Izumi , Kijima Kazuhiro , Ikeda Toshio 
Published: July 2006

Abstract
The Soret coefficients for 0.01 M aqueous solutions of R4NBr (R=H, Me, Et, n-Pr, n-Bu, n-Pen, n-Hex, and n-Hep) were measured by the Snowdon-Turner conductimetric method with accuracy within ±0.1%, and were found to be −0.13, −4.18, −7.16, −9.05, −9.61, −9.47, −8.65, and −7.34, respectively in 10−3 K−1, at the mean temperature 25 °C. They show a maximum at the carbon number 4 or 5 in R, whereas the diffusion coefficients show a minimum at the same carbon number in an exactly inverse manner. The apparatus and procedure are described.
13C Spin-lattice Relaxation and Molecular Motion in Liquid and Plastic 2,2-Dimethylpropanoic Acid
Authors: Hasebe Tooru , Nakamura Nobuo , Chihara Hideaki 
Published: July 2006

Abstract
Individual 13C spin-lattice relaxation times (T1) of 2,2-dimethylpropanoic acid (DMPA) in plastic and liquid phases have been measured by a pulse Fourier transform NMR technique at 15.036 MHz. In the plastic phase (278.9 K to 308.5 K), the minimum in the T1 was observed; 0.35 s at 289.0 K for methyl carbon and 2.67 s at 289.0 K for quaternary carbon. The temperature dependence of the T1 was analyzed by extending Woessner’s treatment to the case of three independent degrees of reorientational freedom; internal methyl reorientation, t-butyl reorientation about C–COOH bonding axis, and isotropic molecular reorientation. In the plastic phase the isotropic reorientation of molecular dimeric units formed through hydrogen bonds is responsible for the 13C-relaxation. The activation parameters for this motion were obtained; Ea=56.4±6.3 kJ mol−1 and τ0=(4.6±4.0)×10−19 s. In the liquid phase from the melting point to 351 K, the T1 showed a monotonous increase with increasing temperature. In this liquid phase the isotropic molecular reorientation of the dimer units of DMPA is also responsible for the 13C-relaxation. The Ea of 23.4±2.4 kJ mol−1 and the τ0 of (9.6±5.8)×10−14 s for this motion were obtained.
VAPOUR PRESSURE, SURFACE TENSION AND DENSITY OF OSMIUM TETROXIDE
Authors: Ogawa Eijiro 
Published: July 2006

Abstract
(I) The structure of osmium tetroxide was discussed.
(II) It was made clear that the phenomenon of an enantiotropy of osmium tetroxide set forth by Krauss did not exist.
(III) The vapour pressure of osmium tetroxide was measured between 15° and 130°C. Melting point, boiling point, heat of sublimation, heat of vaporization, heat of fusion, and free energy change among solid, liquid and vapour were determined.
(IV) Surface tensions and densities from melting point up to 150°C. were determined.
(V) Osmium tetroxide in liquid state somewhat associates below 70°C., though it is a normal liquid above 75°C.
(VI) The critical temperature was determined as 405°C.
Fuel Mixing Effects on Propagation of Premixed Flames. II. Hydrogen+Methane Flames
Authors: Kunioshi Nilson , Fukutani Seishiro 
Published: July 2006

Abstract
Fuel mixing effects on flame propagation were investigated with hydrogen and methane, whose flames, respectively, propagate through two different kinds of mechanisms. The calculated burning velocities did not show linearity with the hydrogen content in the fuel. The addition of only 5% of methane to hydrogen reduces the burning velocity by 20%, notoriously inhibiting the combustion of the mixture. This is caused by obstruction of the harmonious progression of two key chain-branching reactions, resulting in a decrease in hydrogen atom production at the flame front. However, the upstream flux, at the ignition point, of chemical energy due to diffusion of hydrogen atoms from the flame front and the integrated amount of heat released in the low-temperature region did show linearity with the burning velocity. Therefore, it was found that even for flames of mixed fuels whose components burn individually through different propagation mechanisms, the burning velocity can be expressed as a simple linear function of the upstream chemical energy flux or of the amount of heat released in the low-temperature region.
Theoretical Study of Aluminum-Sodium Bimetallic Clusters. I. Geometrical and Electronic Structures of AlnNa (n = 1–4)
Authors: Matsuzawa Hidenori , Hanawa Toshiyuki , Suzuki Kazunori , Iwata Suehiro 
Published: July 2006

Abstract
The geometrical and electronic structures of several small aluminum-sodium mixed clusters AlnNa and pure aluminum clusters Aln (n = 1–4) were examined with ab initio MO calculations. All the calculations were carried out at the restricted Hartree–Fock level of approximation for both closed and open shell systems. The structures of the most stable Aln cluster and neutral and cationic AlnNa clusters were fully optimized. The low and high spin multiplicities of each cluster were examined. The structure of the most stable state of the AlnNa clusters keeps the frame of the Al cluster unchanged, and the Al–Al distances become shorter than in the corresponding Al clusters. The calculated ionization energies by the ΔSCF method are qualitatively in agreement with the corresponding experimental values. The highest occupied molecular orbital of the neutral clusters suggests that an ionized electron is localized on the Al atoms, but the large orbital reorganization by ionization results in a substantial net positive charge on a sodium atom. The nature of chemical bond for the clusters is also examined.
Transformatiom of Propargylic Alcohols into Enones
Authors: Shigemasa Yoshihiro , Oikawa Hiroshige , Ohrai Shin-ichiro , Sashiwa Hitoshi , Saimoto Hiroyuki 
Published: July 2006

Abstract
α,α-Disubstituted propargylic alcohols were transformed into enones by the catalysis with Ag(I) or Ag(I)–Me3SiCl under the mild conditions. This procedure provides a new synthetic method of α,β-unsaturated ketones having an oxygen function at α′ position from 2-butyne-1,4-diol derivatives. 3-Acetoxy-1,4,4-triphenyl-3-buten-2-one was obtained from 4-acetoxy-1,1,4-triphenyl-2-butyn-1-ol by the catalysis with tin(IV) chloride or aluminium chloride.
Synthesis, Properties, and Crystal Structures of a Series of Dinuclear Manganese(III) Complexes with 1,5-Bis(salicylideneamino)-3-pentanol and Various Anions: Formation of a Tetranuclear Manganese(III) Complex
Authors: Mikuriya Masahiro , Yamato Yo , Tokii Tadashi 
Published: July 2006

Abstract
μ-Alkoxo-bridged dinuclear and tetranuclear manganese(III) complexes with 1,5-bis(salicylideneamino)-3-pentanol (H3L), [Mn2(L)(CH3O)Cl2(CH3OH)2] (1), [Mn2(L)(CH3O)(CH3COO)(CH3OH)2]X (X = Br (2), I (3)), [Mn2(L)(CH3O)(CH3COO)(CH3OH)Y] (Y = NCS (4), N3 (5), ClO4 (6)), [Mn2(L)(CH3O)(NCO)2(H2O)2] (7), and [Mn4(L)2(O)2(CH3COO)2]·4H2O·2CH3OH (8) have been prepared and characterized by infrared and electronic spectra, magnetic susceptibilities, and cyclic voltammetry. The molecular structures of 1–5, 7, and 8 were determined by the single-crystal X-ray structure analyses. All the complexes except for 8 have a similar structure, where Cl−, CH3COO−, N3−, NCS−, CH3OH, or H2O is incorporated into the fifth or sixth coordination site on the Mn2(L)(CH3O) plane. The structure of 8, is a tetramer consisting of two Mn2(L)(O)(CH3COO) dimeric units held together through the oxo ions and the phenoxo-oxygen atoms of L. The spectral and magnetic properties were discussed in relation to the crystal structures.
Dual Reactivity of Methoxymethyl Benzenesulfenate in Nucleophilic Substitution
Authors: Okuyama Tadashi , Fueno Takayuki 
Published: July 2006

Abstract
Hydrolysis of methoxymethyl benzenesulfenate is catalyzed by both acid and base. Acid-catalyzed hydrolysis is further accelerated by various nucleophiles like halide ions, thiocyanate, dialkyl sulfide, and the substrate itself. The catalytic constants coincide with those for ethyl benzenesulfenate within 2-fold in magnitude. The nucleophilic reactivity strongly suggests the reaction at the sulfenyl sulfur, but examination of the products from the 18O-labeled substrate showed that the bond cleavage occurs mostly between the oxygen and the proformyl carbon except for the acid-catalyzed water reaction which undergoes the S–O cleavage. A mechanism for a nucleophilic reaction at the sulfur to form a sulfurane intermediate which breaks down with the C–O cleavage is presented. The hydrolysis rate is also strongly dependent on the second order of buffer concentrations in carboxylate and tertiary amine buffer solutions. The third-order term involves both the general acid and the conjugate base of the buffer, and the latter reacts at the sulfur as a nucleophile in the rate-determining step but leads to the C–O cleavage in the same way as the other catalytic nucleophiles.
Catalytic Hydrogenation of Dehydro Quassinoids and Cytotoxic Antitumor Activity of the Hydrogenation Products
Authors: Imamura Kazunori , Fukamiya Narihiko , Okano Masayoshi , Tagahara Kiyoshi , Lee Kuo-Hsiung 
Published: July 2006

Abstract
Two new types of quassinoids (1a, 1b, 2a, 2b, 3a, and 3b) were obtained by the catalytic hydrogenation of dehydro quassinoids [dehydrobruceantin (1), dehydrobruceantinol (2), and dehydrobruceantarin (3)] which were isolated from Brucea antidysenterica. Compounds 1a and 2b showed potent selective cytotoxicity against human medulloblastoma TE-671. Significant cytotoxicity was also demonstrated by 3a for TE-671, for murine leukemia P-388, and 2b for human melanoma RPMI-7951.
Isothiocarbamido Radicals from Thiourea: Electron Spin Resonance Spectroscopy of N-Benzylidene-t-butylamine-N-oxide and 5,5-Dimethyl-1-pyrroline-N-oxide Spin Adducts
Authors: Saha Swapan K , Greenslade David J 
Published: July 2006

Abstract
Amidinothio radicals, NH2(=NH)CS·, formed in the reaction of thiourea and hydrogen peroxide and trapped in aqueous solution by N-benzylidene-t-butylamine-N-oxide (PBN) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin traps are reported for the first time. Stability of the radical is highly dependent on the pH as well as the concentration of thiourea. ESR spectral lines give aN and aβH values as 1.53 mT and 0.24 mT respectively for PBN and 1.46 mT and 2.08 mT respectively for DMPO spin adducts. Preliminary kinetic experiments on the spin trapping reaction are also reported.
Abundance of Cadmium in Paleozoic Limestones in Japan
Authors: Aizawa Shoichi , Akaiwa Hideo 
Published: July 2006

Abstract
Cadmium is significantly enriched in Paleozoic (Permian and Carboniferous) limestones in Japan. The geometric mean of Cd in these limestone samples (n = 111) is 0.57 ppm, which is an order of magnitude higher than that of Quaternary ones. Most of divalent heavy metals in these limestones exist in accessory minerals such as silicates, whereas Cd is contained in calcite. Submarine volcanoes which were active during Paleozoic period might be responsible for the high Cd content of Japanese limestones of this age.