bluuebunny/crossref_metadata_2025_split huggingface dataset:
ENDOR Studies of Vitamin E Model Radical. The Solution Structure and Dynamic Behavior of Chromanyloxyl Ring
Authors: Mukai Kazuo , Takamatsu Kimiko , Ishizu Kazuhiko 
Published: July 2006

Abstract
ENDOR technique has been used to elucidate the solution structure and dynamic behavior of chromanyloxyl ring in vitamin E radical. We have measured the ENDOR spectrum of a stable vitamin E model radical (7-t-butyl-2,2,5-trimethyl-6-chromanyloxyl (1)) in toluene in the temperature range −30°–−100°C. From detailed analysis of the temperature dependence of hyperfine coupling of β-methylene protons in the heterocyclic ring, the equilibrium conformation of the β-methylene group and activation energy, enthalpy and entropy for the conformational interconversion of the heterocyclic ring have been determined. The observed positive temperature dependence of the hyperfine coupling constants (a5CH3 and a8H) may be explained as a consequence of the restricted motion about the C8a–O1 bond in the chromanyloxyl ring, based on the McLachlan MO calculation.
The Conformers of 2,2′-Bipyridine in the Phosphorescent Triplet State as Studied by Electron Spin Resonance and Phosphorescence
Authors: Yagi Mikio , Makiguchi Kazuhiro , Ohnuki Atsushi , Suzuki Kazuhiro , Higuchi Jiro , Nagase Shigeru 
Published: July 2006

Abstract
Two sets of triplet-state ESR spectra corresponding to the s-cis and s-trans conformers of 2,2′-bipyridine have been observed in mixtures of water with various alcohols at 77K. The intensity ratio of the ESR signal for the s-cis conformer to that for the s-trans conformer depends on the composition of the mixture and on the sample-cooling rate. From the analysis of the phosphorescence spectra, the lowest triplet state of the s-cis conformer is estimated to be close to that of the s-trans conformer. An anomalous ESR signal which cannot be ascribed to either the s-cis conformer or the s-trans conformer has been observed in a 1-propanol-water mixture. The geometries of these conformers are discussed from their observed zero-field splitting parameters, together with their potential energy diagrams, as obtained by an ab initio calculation.
Ring-cleavage Reactions of Aromatic Hydrocarbons Studied by FT–IR Spectroscopy. II. Photooxidation of o-, m-, and p-Xylenes in the NOx–Air System
Authors: Bandow Hiroshi , Washida Nobuaki 
Published: July 2006

Abstract
α-Dicarbonyl compounds produced in the photooxidation of o-, m-, and p-xylenes were analyzed quantitatively using long-path FT–IR spectroscopy. Glyoxal, methylglyoxal, and biacetyl were observed in the case of o-xylene, and glyoxal and methylglyoxal were observed in cases of m- and p-xylenes. Yields of glyoxal, methylglyoxal, and biacetyl were 8, 23, and 10% (mole/mole) of o-xylene consumed, respectively. Yields of glyoxal and methylglyoxal were 13 and 42% in the case of m-xylene, and 24 and 12% in the case of p-xylene. These yields could be explained by the ring cleavage of 6,7-dioxabicyclo[3.2.1]octane compounds of OH–aromatics-O2 adduct. Formations of maleic anhydride was observed in the case of o-xylene and it is suggested that maleic anhydride is produced from cis-2-butenedial. Formation of 3-hexene-2,5-dione (unsaturated γ-dicarbonyl) was observed from p-xylene. The ring-cleavage process accounts for 41, 55, and 36% of the total reaction in o-, m-, and p-xylenes, respectively.
Ring-cleavage Reactions of Aromatic Hydrocarbons Studied by FT–IR Spectroscopy. III. Photooxidation of 1,2,3-, 1,2,4-, and 1,3,5-Trimethylbenzenes in the NOx–Air System
Authors: Bandow Hiroshi , Washida Nobuaki 
Published: July 2006

Abstract
Photooxidation of 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes was carried out in the NOx–air system. Formation of glyoxal, methylglyoxal and biacetyl was observed in the cases of 1,2,3- and 1,2,4-trimethylbenzenes, and only methylglyoxal was observed from 1,3,5-trimethylbenzene. Yields of glyoxal, methylglyoxal and biacetyl were 7, 18, and 45% and 8, 37, and 11% of trimethylbenzene consumed in cases of 1,2,3- and 1,2,4-trimethylbenzenes, respectively. The reaction mechanism which was used to explain the yields of α-dicarbonyl compounds from toluene and o-, m-, p-xylenes in the preceding paper (part II) has been applied to explain these yields, and has been found to reproduce these yields well. Formation of 3-hexene-2,5-dione was observed only from 1,2,4-trimethylbenzene. The fractions of the ring-cleavage process in the total reaction were 70, 56, and 64% in cases of 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes, respectively. The yields of the ring-cleavage process are discussed.
Volatility of Low-Henry’s Constant Contaminants in Water
Authors: Okouchi Shoichi , Sasaki Sokichi 
Published: July 2006

Abstract
The volatilization rate of low-Henry’s constant contaminants (less than about 2 m3 Pa/mol) from water to the atmosphere was studied, together with the water volatilization rate, using tracer compounds under various mixing conditions. 1-Butanol, 1-pentanol, 1-hexanol, and 1-heptanol were used as the tracer compounds. The volatilization rates of these compounds and water were controlled by a mass-transfer process in the gas phase. The measured parameter was the ratio of the volatilization rate constant of a tracer(i) to that of water, Kv(i)/Kv(H2O). The obtained ratios agreed with those estimated theoretically. The volatilization rate constant of low-Henry’s constant contaminant(i) in environmental water, Kv(env)(i), can be estimated by multiplying the ratio, Kv(i)/Kv(H2O), by the environmental value of Kv(env)(H2O).
A Temperature Dependence Study of 35Cl NQR Frequencies in Dimethylammonium Hexachlorostannate(IV), Hexachlorotellurate(IV), and Hexachloroplatinate(IV)
Authors: Horiuchi Keizo , Ishida Hiroyuki , Nakamura Daiyu 
Published: July 2006

Abstract
The temperature dependence of 35Cl NQR frequencies was observed for [(CH3)2NH2]2SnCl6, [(CH3)2NH2]2TeCl6, and [(CH3)2NH2]2PtCl6. Two 35Cl NQR frequencies were recorded for the tin complex between 77 and ca. 260 K, the intensity ratio of which was 2:1 for the high- to the low-frequency line. An unusual temperature variation of both frequencies attributable to the motion of the cation was observed, and the existence of a phase transition was suggested. For the tellurium complex, the NQR frequencies were observed below ca. 240 K. At higher temperatures, two signals having the same intensity ratio as that of the tin complex were detected as expected from the isomorphous relation between both complexes proved at room temperature. A phase transition was newly located for this complex at 98 K in addition to another one at 171 K previously reported. The intermediate phase yielded three broad signals having equal intensity, whereas four broad lines could be detected in the low-temperature phase where more than four lines may be expected by referring to the temperature-dependence curves of the NQR lines.
Hydrophobic Indexes for Various Monosaccharides
Authors: Miyajima Koichiro , Machida Katsunosuke , Nakagaki Masayuki 
Published: July 2006

Abstract
The hydrophobic and the hydrophilic surface areas of seven kinds of monosaccharide molecules were calculated by using Hermann’s method. The hydrophobic indexes (Index A and Index B) which are defined as the ratio of the hydrophobic and the hydrophilic surface areas of the molecule are clearly correlated with the partition coefficient of monosaccharide between polystyrene gel and water, and the free energy change of transfer of monosaccharide from water to 1-butanol, indicating that the fraction of the hydrophobic surface area plays an important role in the interaction of monosaccharides and hydrophobic solutes in water.
Studies of Polystyrene-based Ion-exchange Fiber. III. A Novel Fiber-form Chelating Exchanger and Its Adsorption Properties for Heavy-metal Ions
Authors: Yoshioka Toshio 
Published: July 2006

Abstract
Fibrous chelating exchangers with –N(CH2COOH)2 and –N(CH2CH2COOH)2 groups have been prepared for the first time by using a polystyrene–polypropylene composite fiber as the starting material. They have large surface areas per unit of weight and can be utilized in various forms. The properties of adsorbing Cu2+ are compared between these chelating fibers and an ordinary chelating resin. The former groups form more stable complexes with Cu2+ than the latter, probably because of their different chelating structure. The rate of the adsorption of Cu2+ to the fibers is dependent upon their water content and is from ten to fifty times as high as that to the resin. These results are explained by assuming that the diffusion within the exchangers is the major rate-controlling step in the adsorption process. The diffusion equation of isotopic ion exchange for a cylindrical endless fiber was solved in the case of ideal particle-diffusion control by modifying the method used for a spherical resin. The experimental data are interpreted in terms of their theoretical solutions. For practical application, the removal of Cu2+ and Mn2+ from various solutions was also carried out by using fixed-beds of these chelating fibers.
Photoelectrochemical Behavior of p-Type Boron Phosphide Photoelectrode in Acidic Solution
Authors: Lee Ju-seong , Fujishima Akira , Honda Kenichi , Kumashiro Yukinobu 
Published: July 2006

Abstract
The photoelectrochemical behavior of p-type boron phosphide (p-BP) in acidic solution was investigated. The p-BP photocathode was stable in sulfuric acid solution under irradiation, and the band gap deduced from the photocurrent action spectrum in acidic solution was 2.0 eV. The gas evolved from p-BP photocathode was hydrogen which was obtained with a current efficiency of ca. 100%. The photocurrent was markedly increased by suitable ruthenium treatment of the BP. A photoelectrochemical cell (PEC), Pt(H2)/0.5 M H2SO4(1 M=1 mol dm−3)/ /0.5 M H2SO4/p-BP, was shown to have an open-circuit photovoltage of 0.45 V and a fill factor of 0.25.
Surface Treatment of meso-Carbon Microbeads by Oxygen Plasma
Authors: Sugiura Masaaki , Esumi Kunio , Meguro Kenjiro , Honda Hidemasa 
Published: July 2006

Abstract
A surface treatment of meso-carbon microbeads was carried out using an oxygen plasma to improve the wettability in aqueous solution. The surface acidity of meso-carbon microbeads increased with treating time and the pH of the aqueous dispersion shifted to lower values. The zeta potential varied with treating time from a positive to a negative value. Further, the turbidity behavior of aqueous dispersion with treating time was similar to that of surface acidity. From these results, it was found that the surfaces of meso-carbon microbeads were oxidized by oxygen plasma, resulting in an enhancement of wettability of meso-carbon microbeads in an aqueous solution.
A Nuclear Magnetic Resonance Study of the Exchange Reaction of Dimethyl Sulfoxide in Pentakis(dimethyl sulfoxide)oxovanadium(IV) Ions
Authors: Kaya Kiyoshi , Ikeda Yasuhisa , Fukutomi Hiroshi 
Published: July 2006

Abstract
The dmso exchange reaction in [VO(dmso)5]2+ has been studied in the mixture of CD3NO2 and DMSO by means of 1H NMR. The exchange rate is independent of the free DMSO concentration and the kinetic parameters are as follows: kex(25 °C)=1.76×103 s−1, ΔH\eweq=60.1±4.3 kJ mol−1, and ΔS\eweq=18.5±12.9 JK−1 mol−1.
Hydrophobic Vitamin B12. IV. Addition Reactions of Alcohols to Olefins as Catalyzed by Hydrophobic Vitamin B12 Derivatives
Authors: Murakami Yukito , Hisaeda Yoshio 
Published: July 2006

Abstract
Addition reactions of alcohols to olefins were catalyzed by hydrophobic vitamin B12 derivatives under aerobic irradiation conditions at the room temperature range. Ethyl vinyl ether, 1-pentene, and cyclohexene were adopted as olefins, while heptamethyl methylaquacobyrinate perchlorate and heptamethyl cyanoaquacobyrinate perchlorate were used as the starting complexes. Heptamethyl cobyrinate, which was generated from heptamethyl methylaquacobyrinate perchlorate by aerobic photolysis, is an appropriate catalyst for investigation of the reaction mechanism because the alkylated complex having the cobalt–carbon σ-bond, the reaction intermediate, has a long lifetime sufficient for its identification in the dark. On the other hand, heptamethyl cyanocobyrinate, which was derived from heptamethyl cyanoaquacobyrinate, is superior to heptamethyl cobyrinate as the catalyst for the addition reaction. The reaction proceeds via light-promoted decomposition of the alkylated complex, and the catalyst is regenerated upon autoxidation by air. These hydrophobic vitamin B12 derivatives are particularly effective homogeneous catalysts for the addition of an alcohol to an electron-rich olefin. Plausible reaction schemes for the catalytic cycle have been presented on the basis of experimental findings.
Preparation of Michael Adducts of Isobutyraldehyde and Acetylenecarboxylic Esters via N-Isobutylidene-t-butylamine
Authors: Miyajima Shingo , Ito Kunio 
Published: July 2006

Abstract
N-Isobutylidene-t-butylamine reacted with methyl propiolate or dimethyl acetylenedicarboxylate to afford the Michael adducts predominantly. The adducts were converted to the corresponding formyl esters.
Three-dimensional Aromaticity of Ferrocene
Authors: Aihara Jun-ichi 
Published: July 2006

Abstract
The conjugated systems of ferrocene and related compounds were constructed using five equivalent 3d orbitals of iron and carbon 2pz orbitals of the cyclopentadienyl or pentadienyl groups. Ferrocene with such a conjugated system was found to have positive resonance energy due to cyclic conjugation, and was characterized as a three-dimensional aromatic species.
Decompositions of Tropone Tosylhydrazone Sodium Salt in the Presence of Cyclopentadienone Derivatives. [4+2]-Type Cycloaddition Reactions of Cycloheptatrienylidene or 1,2,4,6-Cycloheptatetraene with Cyclopentadienone Derivatives
Authors: Saito Katsuhiro , Ishihara Hiraku 
Published: July 2006

Abstract
Tropone tosylhydrazone sodium salt, the precursor of the cyclic conjugated carbene (cycloheptatrienylidene), was decomposed in the presence of various cyclopentadienone derivatives to give endo- and exo-[4+2]-type adducts and benzotropylidene derivatives. The product ratios between the endo-[4+2]-type adducts and the exo-[4+2]-type adducts are considered to suggest that these addition reactions proceed via a cyclic conjugated allene (1,2,4,6-cycloheptatetraene), which is a valence-bond isomer of cycloheptatrienylidene. Upon heating, the [4+2]-type adducts gave the benzotropylidene derivatives via decarbonylation reactions followed by 1,5-hydrogen shifts.
Constituents of Seeds of Brucea javanica. Structures of New Bitter Principles, Yadanziolides A, B, C, Yadanziosides F, I, J, and L.
Authors: Yoshimura Shin , Sakaki Toshiro , Ishibashi Masami , Tsuyuki Takahiko , Takahashi Takeyoshi , Honda Tadashi 
Published: July 2006

Abstract
Three new quassinoids and four new quassinoid glycosides were isolated from water-soluble fraction of methanol extract of seeds of Brucea javanica (L.) Merr, known as “Ya-dan-zi” in Chinese folklore and their structures were determined by spectral and chemical means. Yadanziosides F, I, J, and L were demonstrated to have antileukemic activity.
Structures of New Quassinoid Glycosides, Yadanziosides A, B, C, D, E, G, H, and New Quassinoids, Dehydrobrusatol and Dehydrobruceantinol from Brucea javanica (L.) Merr
Authors: Sakaki Toshiro , Yoshimura Shin , Ishibashi Masami , Tsuyuki Takahiko , Takahashi Takeyoshi , Honda Tadashi , Nakanishi Toshihiro 
Published: July 2006

Abstract
Quassinoid glycosides, yadanziosides A, B, C, D, E, G, and H, and two quassinoids, dehydrobrusatol and dehydrobruceantinol were isolated from seeds of Brucea javanica, and their structures were determined. These glycosides showed bitter taste and were demonstrated to have antileukemic activity.
Improved Catalytic Activity of Cyclopentadienylcobalt in the Preparation of Pyridines from Acetylenes and Nitrites
Authors: Wakatsuki Yasuo , Yamazaki Hiroshi 
Published: July 2006

Abstract
The catalytic activity of cyclopentadienylcobalt increases greatly upon introducing a methoxycarbonyl group into the cyclopentadienyl ring, and by carring out the reaction with a vigorous exclusion of oxygen. Among the precursors we have examined, the most active one was [Co(Cpz)(cot)] (Cpz=methoxycarbonylsubstituted cyclopentadienyl; cot=cyclooctatetraene) which can generate the active species at 100 °C.
Solvent Effects on Absorption Spectra of Substituted Azobenzenes
Authors: Sueishi Yoshimi , Asano Mari , Yamamoto Shunzo , Nishimura Norio 
Published: July 2006

Abstract
McRae’s formula including the quadratic term was applied to an analysis of absorption spectra of substituted azobenzenes in various solvents. It has been suggested that the interaction between the solvent dipole and the solvent-induced solute dipole plays an important role.
79Br and 127I Nuclear Quadrupole Resonance of Mixed Valency Compounds Ga2X4(X=Br, I)
Authors: Okuda Tsutomu , Hamamoto Hiroshi , Ishihara Hideta , Negita Hisao 
Published: July 2006

Abstract
79Br and 127I nuclear quadrupole resonances(NQR) were observed in α-Ga2Br4, β-Ga2Br4, and Ga2I4 at various temperatures. Resonance lines disappeared at 353, 335, and 448 K for α-, β-Ga2Br4, and Ga2I4 respectively. The wide separation of the 127I resonance lines in Ga2I4 may be attributed to the interaction between the Ga+ ions and the I atoms.
A Through Space/Bond Interaction Analysis on the Shape of Band Structure of Polynitrilomethylidyne
Authors: Aoki Yuriko , Imamura Akira , Teramae Hiroyuki 
Published: July 2006

Abstract
The concept of the through space/bond interaction presented by Hoffmann et al. was extended to study electronic states of polymers. The band shape of lone pair orbitals was investigated by truncating converged Fock matrices and overlap integrals except for the terms corresponding to the through bond and particular through space interactions. This method was used by applying the ab initio tight-binding crystal orbital method to three isomers of one-dimensional polynitrilomethylidyne, for which the dependences of the lone pair orbital energy on the wave number vector differ significantly from one another. The band shape of the lone pair orbital is related intimately to the interaction with H atoms. The effect of each through space interaction on the band shape of the lone pair orbital may be reasonably interpreted in terms of the symmetry of crystal orbitals. This method seems expedient for analyzing qualitatively lone pair bands of various polymers at the ab initio level.
Oxidation of Triose Reductone by Oxidizing Inorganic Radicals Generated by Pulse Radiolysis
Authors: Horii Hideo , Abe Yasuo , Taniguchi Setsuo 
Published: July 2006

Abstract
Triose reductone (2,3-dihydroxy-2-propenal) was oxidized by Cl2−·, Br2−·, (SCN)2−·, and N3· to produce a triose reductone radical which had an absorption maximum at 398 nm, ε=5500 M−1 cm−1 (1 M=1 mol dm−3) and decayed by second-order kinetics. The rate constants for the reactions of triose reductone with these oxidizing inorganic radicals were obtained. The pKa of this radical was found to be 1.4.
The Synthesis, and the Crystal and Molecular Structure of [Diaquatetrakis(thiocyanato)cobalt(II)mercury(II)]-N,N-Dimethylacetamide (1/2), CoHg(SCN)4(H2O)2·2{CH3CON(CH3)2}
Authors: Kinoshita Hisashi , Shimoi Mamoru , Ouchi Akira , Sato Shoichi 
Published: July 2006

Abstract
The new complex indicated in the title was synthesized and its crystal and molecular structures were determined by the use of a single-crystal X-ray diffraction method. The crystal is tetragonal, with the space group P\bar4, and the cell constants are a=12.124(5) and c=7.985(2) Å. The structure was solved using the heavy-atom method, and the final R value was 0.039. Two kinds of crystallographically independent mercury atoms in the unit cell are tetra-coordinated and they are in the tetrahedral geometry, where four sulfur atoms of the thiocyanate ions are ligated, respectively. The cobalt atom is hexa-coordinated, and is in an octahedral geometry, where four nitrogen atoms of the thiocyanate ions are coordinated equatorially, and two water oxygen atoms axially. Thiocyanate ions span mercury and cobalt atoms to form two-dimensional networks parallel to the (001) plane. The planar polymeric complexes are linked to the c-axis direction, through hydrogen bonds between coordinated water molecules and N,N-dimethylacetamide.
Reactions of Enolic Biotin Models
Authors: Kondo Hiroki , Miura Katsuhito , Seki Eiji , Sunamoto Junzo 
Published: July 2006

Abstract
In order to delineate the mechanism of biotin-dependent carboxylation reactions, the following model experiments have been carried out. In reactions of carbonate derivatives such as methyl chloroformate with 2-ethoxy-2-imidazoline (1), a putative enolic biotin model, or 2-imidazolidinone (2), the former showed a much higher reactivity to provide the methoxycarbonylated 1 (3). Reactions of 3 with benzenethiolate, cyclohexylamine and carbanions have also been investigated as a model of transcarboxylation from N-carboxybiotin to an acceptor substrate. Only carbanions attack the carbonyl carbon of 3, leading to rupture of the C–O bond, but not of the N–C bond. A net “carboxyl” transfer was effected with 1-methoxycarbonylimidazole (9) as a donor substrate. Implications of these results in biotin catalysis are discussed.
Benzofuran Derivatives. II. Synthesis of 2,3-Dihydrobenzofurans from Ethyl 2-Acylphenoxyacetates
Authors: Suzuki Tsuneo 
Published: July 2006

Abstract
Ethyl 3-alkyl-3-hydroxy-5-nitro-2,3-dihydro-2-benzofurancarboxylates were obtained from the reaction of ethyl 2-acyl-4-nitrophenoxyacetates with potassium hydroxide in dry dioxane. The relative ratios of the cis and trans isomers with respect to C-2 and C-3 stereochemistry varied according to the structure of the acyl group. When the acyl group was acetyl, propionyl, or isobutyryl group, the cis isomers (2-alkoxycarbonyl groups and 3-hydroxyl groups are cis) were exclusively obtained in high yields. On the other hand, a nearly equimolecular amount of the cis and trans isomers was obtained from the reaction of 2-formyl derivatives under the same conditions.
Ozonolysis of 3-Methyl-1-phenyl-4-phenylazo-5-pyrazolone
Authors: Matsui Masaki , Konda Akihiro , Shibata Katsuyoshi 
Published: July 2006

Abstract
In chlorinated solvents, 3-methyl-1-phenyl-4-phenylazo-5-pyrazolone (1) easily reacts with ozone to give benzene (2), phenol (3), chlorobenzene (4), o-chlorophenol (5), biphenyl (6), and 3-methyl-1-phenyl-2-pyrazoline-4,5-dione (7). The formation of these products is explained by an electrophilic ozone attack on the hydrazone tautomer 1′.
Electronic and Steric Effects of Alkyl Group on Denitrosation of 3-Alkyl-1-methyl-1-nitrosothioureas
Authors: Isobe Masayoshi 
Published: July 2006

Abstract
A series of 3-alkyl-1-methyl-1-nitrosothioureas with R=CH3, C2H5, cyclo-C6H11 (3), (CH3)2CH (4), C2H5(CH3)CH, and (CH3)3C were synthesized and their rates of acid catalyzed (pH&lt;6.5) denitrosation measured. According to rate measurements in CH3COOD–D2O, the kinetic isotope effect kH:kD is 1.25 for 4. Except 3, a linear plot of logkR⁄kMe for the denitrosation of RNHCSN(NO)CH3 vs. σ* provides ρ*=−0.98 (r=−0.997). The significant factor affecting the rate-determining step of the denitrosation of these N-nitrosothioureas at pH 4.6 is the electronic effect of the substituent at the N3 position.