bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methylation of a Benzene Ring as a Chemical Signal. Marked Changes in the Pattern of Temperature Dependence of the Selectivity in Oxidation of a Pair of Associating Thiols
Authors: Endo Tadashi , Okubo Akihiro , Kaneko Yuji , Uehara Masatoshi , Tasai Hidetoshi , Sato Akiyoshi , Nikki Kunio , Nakagawa Naoya , Kamei Shinichi 
Published: July 2006

Abstract
Temperature dependence of the selectivity [the ratio of an unsymmetrical disulfide to symmetrical one] has been studied in oxidation of a pair of associating thiols, each with the recognition site [C6H4N(CH3)2 and R1], with O2 in 80% (v/v) acetonitrile–20% water in the range of −10 to 70 °C. The selectivity for R1=C6H4CH3 shows a minimum at 35 °C, whereas for R1=C6H5 the selectivity exhibits a maximum at 35 °C; for R1=C6H4C2H5 plots of the selectivity against temperature shows a sigmoid-like curve. The selectivity in oxidation of a pair of non-associating thiols, 2-(dimethylamino)ethanethiol and a para-substituted benzenethiol, remains practically unaltered with temperature in the same solvent. Though thiol-disulflde exchange reaction proceeds slowly below 35 °C, the selectivity in the exchange differs entirely from that in the oxidation. It has been found that changes in hydrophobicity with R1 and temperature cannot explain dramatic alterations in the selectivity with R1 and temperature.
Syntheses of 2-Amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline and Its Related Compounds
Authors: Kasai Hiroshi , Nishimura Susumu 
Published: July 2006

Abstract
The strongly mutagenic compound, 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (Me-IQ), isolated from broiled sardines was synthesized from 6-amino-7-methylquinoline. Several structurally related compounds were also synthesized to clarify the structure-activity relationship. Some of them also showed strong mutagenic activity towards Salmonella typhimurium TA98.
The Effect of Quaternary Phosphonium Halides on the Temperature of the Maximum Density of Water
Authors: Takaizumi Katsuko , Wakabayashi Toshiki 
Published: July 2006

Abstract
The shifts in the temperature of the maximum density(tmd) of water produced by quaternary phosphonium halides, (n-Bu)4−nPhnPX(n=0–4), were measured dilatometrically, and the Despretz constants, KD, were determined. The KD, which is positive when the tmd is lowered by a solute, increases nearly linearly with increasing n from 1.16 kK for (n-Bu)3PhPCl to 1.57 kK for Ph4PCl, while the KD for Bu4PCl, 0.933 kK, is considerably lower than that to be expected from those for other members. Since the standard partial molal volumes of the cations have been found to be nearly the same, the variation in KD with n would originate from the difference in ion-water interaction between the cations. Some estimation was made for the contribution of the structural effect of the cations on the solvent water (Kst). The Kst is largely negative for the Bu4P+ ion, indicating that the cation is a structure maker. The Kst becomes less negative as n increases, indicating that the structure-making ability decreases with an increase in n.
Monolayers of Alkylammonium Alkanesulfonates
Authors: Shibata Osamu , Kaneshina Shoji , Nakamura Makoto , Matuura Ryohei 
Published: July 2006

Abstract
The surface pressure-area (π-A) curves for monolayers of cation-anion double long-chain salts, alkylammonium alkanesulfonates, were determined at the air-water interface by the Langmuir method. When the total chain length of cation and anion was constant, the transition pressure from the expanded to the condensed state in the monolayer was lowered as the chain length of cation elongated, and the lowest pressure at the transition point was observed in the case of the equal chain length of cation and anion. The lower the pressure at the transition point, the larger the value of the mean area per molecule at that point. The apparent molar entropy, enthalpy, and energy of transition from the expanded to the condensed phase were calculated from the temperature dependence of the transition pressure on the π-A curve. All the values calculated were negative. The magnitude in the changes of the apparent molar quantities was greatest when both a cationic and an anionic chain had the same length. These results were interpreted in terms of the orientation of double long-chain salt in the condensed state of monolayer. The increase in the chain length of cation and anion tends to increase the values of apparent molar quantity changes. The contributions of long-chain anion and cation to the phase transition of monolayer are not equivalent; the condensing effect of long-chain cation is larger than that of long-chain anion.
High Performance Liquid Chromatography Using Polymer Gels for Direct Analyses and Characterizations of Soluble Organic Pollutants in Water
Authors: Urano Kohei , Furuune Hiroyuki , Hayashi Koji 
Published: July 2006

Abstract
The optimum conditions in HPLC separations using columns packed with polymer gels were investigated for analyzing and characterizing directly various organic pollutants in water without complicated pretreatment. Experimental results showed that polystyrene gel column was unsuitable for direct analyses of water samples. Direct analyses of various organic compounds in water could be achieved on polyacrylester and polyhydroxystyrene columns by using 0.02 mol L−1 phosphoric acid and acetonitrile (85:15) as a mobile phase. At 40 °C, these systems of column and mobile phase gave values of height equivalent to a theoretical plate ranging from approximately 0.10 to 0.25 mm and retention times ranging from approximately 8 to 60 min for various compounds in water. Separation characteristics of these polymer column systems were discussed by taking into account solubilities, functional groups, aromaticities, or molecular weights of organic compounds in water. Furthermore, several wastewaters and their treated waters were directly analyzed for examples.
The Effect of the Vanadium Component on the Life of the WO3–TiO2 Catalyst Used for the Reduction of NOx, with NH3
Authors: Morikawa Shigeru , Takahashi Kazumasa , Mogi Junichi , Kurita Satoru 
Published: July 2006

Abstract
The 5000-h life test of the WO3–TiO2 catalyst for the reduction of NOx with NH3 has been investigated in real flue gases containing vanadium and SOx on a pilot plant. When the present catalyst was used in a residual-oil-fired-boiler flue gas, steady activities over 90% of NOx reduction were achieved for 5000 h at 400 °C (space velocity: 2700 h−1). On the other hand, when the catalysts were taken out of the reactors at certain intervals and studied by means of a laboratory reactor, they were much more active than fresh catalyst at lower temperatures (250–350 °C). Also, the SO2 oxidation efficiency increased with the reaction time. This activation was considered to be due to the vanadium component in the flue gas.
Concentration Dependence of Ketone Hydrogenation Catalyzed by Ru, Pd, and Pt. Evidence for Weak Ketone Adsorption on Pd Surface
Authors: Sungbom Choi , Tanaka Kazunori 
Published: July 2006

Abstract
As the ketone (cyclohexanone, 4-heptanone) concentration in cyclohexane was increased, the hydrogenation rate saturated even below 0.05 mol dm−3 on Ru and Pt, but at a much higher concentration of around 0.5 mol dm−3 on Pd. This result suggests that ketone adsorption on Pd is weak in comparison with other platinum group metals.
The Formation of Anion Radicals in Glassy N-Propyl and N-Benzyldimethacryloylamines γ-Irradiated at 77 K
Authors: Kodaira Toshiyuki , Taniguchi Makoto , Hase Hiroaki , Matsuyama Tomochika 
Published: July 2006

Abstract
N-Propyl- and N-benzyldimethacryloylamines irradiated by γ-rays from 60Co in their glassy state at 77 K yield anion radicals of their methacryloyl groups. These anion radicals afford a triplet with a coupling constant of 1.1 mT on measurement of the ESR and are bleached by a high-pressure mercury lamp at 77 K.
The MoO3–SnO2 Catalysts. Acid-Base Properties and Catalytic Activities for 2-Butanol Decomposition and 1-Butene Isomerization
Authors: Jin Tuo , Hattori Hideshi , Tanabe Kozo 
Published: July 2006

Abstract
Acidic and basic properties of MoO3–SnO2 catalysts with different compositions of MoO3 were measured by adsorption of NH3, CO2, and acid-base indicators. Acidic property prevailed over basic property for all catalysts. Catalytic activities for 2-butanol dehydration and 1-butene isomerization correlated with the acidities measured under the reaction conditions.
Electrophoretic Behavior of Adenine, Adenosine, and Adenosine Nucleotides in Ion Exchange Cellulose Paper as a Support
Authors: Kitaoka Yoshinori 
Published: July 2006

Abstract
Studies have been carried out on the effects of cationizable and anionizable groups of ion exchange cellulose papers on an electroosmotic flow over a range of pH=5–10 and on the electrophoretic migrations of adenine, adenosine, and adenosine nucleotides. The ionizable groups strongly affected the mobilities of adenosines.
Studies of Lead-complex Formation in Sea Water by Anodic Stripping Methods
Authors: Nakata Ryuji , Okazaki Satoshi , Fujinaga Taitiro 
Published: July 2006

Abstract
For the purpose of the determination and chemical speciation of trace lead in sea water by the use of an electrolytic concentration technique, the effects of the pH on the reduction potential of lead ions in the presence of various organic and inorganic ligands were investigated. In the pH range below ca. 5, the lead–chloro complex is dominant in sea water. Even in the presence of organic model ligands such as nitrilotriacetic acid (NTA), the electroactive species of lead was also its chloro complex when the sample solution was acidified enough below pH 2.
The Synthesis and Reactions of 2,6-Dimethyl-4-silaspiro[3.4]oct-6-ene
Authors: Terunuma Daiyo , Shibuya Noriyuki , Nohira Hiroyuki 
Published: July 2006

Abstract
A new silaspiro compound, i.e., 2,6-dimethyl-4-silaspiro[3.4]oct-6-ene, was synthesized by treating 1,1-dichloro-3-methyl-1-silacyclobutane with isoprene in the presence of magnesium in tetrahydrofuran. The reactions of the silaspiro compound with LiAlH4, H2PtCl6, dimethyl acetylenedicarboxylate in the presence of PdCl2(PPh3)2, and the Simmons-Smith agent were investigated.
A Convenient Synthesis of 2-Deuterio-1,3-benzodithiolylium Salts. Useful Synthon for the Preparation of One-carbon Homologated 1-Deuterio Aldehydes
Authors: Nakayama Juzo 
Published: July 2006

Abstract
2-Deuterio-1,3-benzodithiolylium salt, a useful synthon for preparation of one-carbon homologated 1-deuterio aldehydes, can be prepared in excellent overall yield in three steps starting from easily accessible 2-isopentoxy-1,3-benzodithiole.
The Stereoselective Diels-Alder Reaction of Bicyclo[3.2.0]nona 3,6-dien-2-one with Several Dienes
Authors: Takeshita Hitoshi , Hatsui Toshihide , Shimooda Isao , Mametsuka Hiroaki 
Published: July 2006

Abstract
The endo-cis adducts were selectively obtained by the Diels-Alder reaction of several dienes with bicyclo[3.2.2]nona-3,6-dien-2-one, prepared from tropone and ethylene. This selective formation from the bicyclic dienophile, the isolated C=C and ethano C–C bonds of which are situated in similar sterical environments within the molecule, was supported by an Extended Hückel calculation.
Synthesis of a 6-Methylpyridoxine Hydrochloride Derivative as an Electrophilic Precursor for Pyridoxal-like Functionalization
Authors: Iwata Masaaki , Kuzuhara Hiroyoshi 
Published: July 2006

Abstract
Through a key step of regioselective rearrangement of 5′-O-acetyl-3,4′-O-isopropylidene-6-methylpyridoxine 1-oxide, stable 5′-deoxy-2′,5′-dichloro-3,4′-O-isopropylidene-6-methylpyridoxine hydrochloride, which is expected to be a strong electrophile in an HCl free form, was synthesized from Dl-alanine in good yield.
X-Ray Microanalysis of Uranium on Fibrous Amidoxime-type Adsorbent
Authors: Kitamura Takao , Sakane Koji , Katoh Shunsaku 
Published: July 2006

Abstract
The adsorption process for uranium from sea water was studied by X-ray microanalysis on polyacrylamidoxime fiber, whose functional group was found to distribute uniformly. Uniform distribution of uranium was observed on cross sections of the adsorbents, which had contacted with sea water for 14 and 55 d. It was deduced that intrafiber diffusion of uranium is not the rate determining step in adsorption.
Crystal Structure of Mixed-valence Compound 1′,1'″-Dipropylbiferrocenium Triiodide with Averaged-valence Type Irons at 298 K and with Trapped-valence Type Irons at 110 K and Thermal Electron Transfer Process of Mono-oxidized Binuclear Ferrocene Derivatives
Authors: Konno Michiko , Hyodo Shi-aki , Iijima Sei-ichiro 
Published: July 2006

Abstract
The crystal structure of 1′,1'″-dipropylbiferrocenium (PrFcFcPr)+I3−, which shows averaged-valence irons at 298 K and trapped-valence irons at 110 K, was determined by X-ray diffraction. The crystal at 298 K is triclinic, space group P\bar1, a=8.5148(8), b=8.5482(5), and c=10.9032(13) Å, α=89.546(9), β=115.582(9), and γ=108.488(7)°, U=671.10(9) Å3, and Z=1. The crystal at 110 K is triclinic, space group P1, a=8.431(2), b=8.478(2), and c=10.816(3) Å, α=88.58(3), β=117.39(2), and γ=108.65(2)°, U=643.4(3) Å3, and Z=1. Structures were refined to R=0.042 at 298 K and R=0.050 at 110 K. At 298 K cation (PrFcFcPr)+ sits on the symmetry center and the two Fc units are crystallographically equivalent, whereas at 110 K the symmetry center is lost and ferrocene-like and ferrocenium-like Fc units are distinguished. A three-dimensional hydrogen-bond network is clearly found between the cation and iodine atoms at 110 K, in contrast to the result at 298 K. Infrared spectra of 1′,1'″-diethyl- and 1′,1'″-dipropylbiferrocenium+I3− and μ-(as-indacenyl)-bis(cyclopentadienyliron)+I3−0.5I2 salts measured at 294 and 78 K indicate that a remarkable change in peak intensity is observed at 680 and 1525 cm−1 in the dialkyl salts, whereas no change is found in the remainder.
Transient Species in Picosecond Pulse Radiolysis of Liquid Carbon Tetrachloride
Authors: Sumiyoshi Takashi , Sawamura Sadashi , Koshikawa Yoshio , Katayama Meiseki 
Published: July 2006

Abstract
Formation and decay of transient species produced in pure liquid carbon tetrachloride by ionizing radiation were studied by using a stroboscopic pulse radiolysis technique in the time region 35–350 ps. Optical absorption spectra show two principal bands. One narrow band centered at 325 nm, which is formed during each fine structure electron pulse and decayed after pulse with t1⁄2=6.5 ns, is attributed to CCl4+ cation. The other broad band centered at 470 nm built up after electron pulse is assigned to (CCl4+·Cl−). A consideration on effects of cation scavengers on these bands furnishes a support for the above assignment.
Pulse Radiolysis Studies on Methyl Methylthiomethyl Sulfoxide in Aqueous Solutions
Authors: Sumiyoshi Takashi , Miura Nobuyuki , Aikawa Masayuki , Katayama Meiseki 
Published: July 2006

Abstract
Reaction mechanisms between methyl methylthiomethyl sulfoxide (MTMSO) and hydrated electron (eaq−) or hydroxyl radical (OH· radical) have been studied in aqueous solutions with various pH values by means of pulse radiolysis technique. The acid and basic components of equilibrium
(Remark: Graphics omitted.)
and
(Remark: Graphics omitted.)
are formed for the reaction of eaq−+CH3SCH2SOCH3 and OH· +CH3SCH2SOCH3, respectively. The pKa values of the respective equilibrium are 10 and 9. The anion (I) and (II) have absorption maxima at 375 nm and 360 nm, respectively. The sulfinic acid CH3SCH2SO2− is also formed in the reaction of CH3SCH2SOCH3+OH·. The rate constants have been determined to be k(eaq−+MTMSO)=1.3×108 M−1 s−1 and k(OH· +MTMSO)=3.1×109 M−1 s−1 (1 M=1 mol dm−3). Relative reactivities of OH· radical with thio-methyl bond and sulfinyl group are also discussed.
Dynamic Studies on Electron Transport Across Micellar Phase. Intermicellar Migration of Hydrated Electrons
Authors: Aikawa Masayuki , Sumiyoshi Takashi , Miura Nobuyuki , Katayama Meiseki 
Published: July 2006

Abstract
The dynamics of hydrated electrons generated by pulsed electron beams was studied for micellar systems with a series of halogenated naphthalenes as substrates exclusively dissolved in micellar phase. Time behavior of absorption for hydrated electrons, displayed as a curve consisting of two exponential decays, affords evidence that two different routes exist in advance of dissociative electron attachement: 1) direct penetration of electrons through micellar phase with substrates, and 2) migration of hydrated electrons between micells in the absence and presence of substrates, prior to the penetration of electrons into the reactive center in the micelle. Electrostatic interaction of hydrated electrons with positively charged surface of micelles is also discussed.
Structures of Cys-containing Peptide Complexes of Pd(II) in Organic Solvents
Authors: Ueyama Norikazu , Sasaki Kazuko , Nakata Michio , Nakamura Akira 
Published: July 2006

Abstract
Cysteine-containing peptide (pep) complexes of Pd(II) have been synthesized and their structures in organic solvents such as dimethyl sulfoxide (Me2SO) and N,N-dimethylformamide (DMF) were examined by use of 1H-, 13CNMR, visible, and CD spectroscopies. In all cases of the Pd(II) complexes, only the thiolato group of the peptides coordinates to the metal. Upon mixing [PdCl4]2− and the peptide, a trans(S) isomer [PdCl2(pep)2]2− immediately forms, which gradually isomerizes to the cis(S) isomer at 20 °C in DMF. The reactivity of Pd(II)–S bonds in these complexes was examined by addition of 2,2′-bipyridyl, 2-mercaptoethanol, or 3,4-toluenedithiol.
Syntheses, Structure, and Properties of Several Bis(O,O′–dialkyl dithiophosphato)cobalt(II)Adducts
Authors: Shimoi Mamoru , Ouchi Akira , Uehiro Takashi , Yoshino Yukichi , Sato Shoichi , Saito Yoshihiko 
Published: July 2006

Abstract
Several amine or phosphine adducts of bis (O,O′-dialkyl dithiophosphato)cobalt(II), which were hardly oxidized in air at room temperature, were obtained as crystalline solids. The crystal and molecular structure of one adduct, Co(Me2dtp)2(triphenylphosphine) (Me2dtp=O,O′-dimethyl dithiophosphato group), was determined by means of the X-ray diffraction method. The crystal is monoclinic: space group P21/n, a=26.712(4), b=9.495(1), c=11.180(5) Å, β=95.43(3)°, Z=4, Dx=1.495, Dm=1.45 g cm−3, μ(Mo Kα)=1.17 mm−1, and the final R value obtained is 0.062 for 4466 observed reflections. The coordinated atoms around the cobalt atom are in a trigonal bipyramidal configuration. The approximate first formation constants of the adducts, K=[Co(II)(R2dtp)2·X]/{[Co(II)(R2dtp)2][X]} (R=alkyl group, and X=donor) in solution, were obtained by means of the spectrophotometric as well as the NMR technique.
Theoretical Prediction of Cotton Signs in CD Spectra of Λ-[Co(N)2(O)4]−- and Λ-[Co(N)4(O)2]+-type Complexes
Authors: Fujinami Shuhei , Tsuji Kenshi , Shibata Muraji 
Published: July 2006

Abstract
The crystal field model of d-d optical activity has been applied to complexes with cis(N)-[Co(N)2(O)4]− and cis(O)-[Co(N)4(O)2]+ chromophores, and the Cotton signs of these complexes have been predicted. The model has shown that the Cotton signs in CD spectra of the complexes depend upon: 1) the energy difference between Ega and A2g states, 2) the coordination angle in a bidentate chelate, and 3) the effective charge of the ligating atoms. The CD spectral difference between an optically active carbonato complex and the corresponding diaqua complex derived from the carbonato complex has been understood in terms of the effective charge of the ligating O atoms.
Cobalt(III) Complexes with Tripodlike Quadridentate Ligands. III. Absorption and Circular Dichroism Spectra of Cobalt(III) Complexes Containing N-(2-Aminoethyl)iminodiacetate and Amino Carboxylate or 1,2-Diamine
Authors: Akamatsu Keiji , Komorita Takashi , Shimura Yoichi 
Published: July 2006

Abstract
Glycinato, l-alaninato, ethylenediamine, N,N-dimethylethylenediamine, (R)-propylenediamine, (R,R)-1,2-cyclohexanediamine and meso-2,3-butanediamine cobalt(III) complexes of a tripodlike ligand, N-(2-aminoethyl)iminodiacetate have been prepared. The geometrical configurations are assigned on the basis of their absorption, circular dichroism, and 1H-NMR spectra. The trans(O) isomer of meso-2,3-butanediamine complex is optically resolved and the relationship between the absolute configurations of the chiral 1,2-diamine complexes and their circular dichroism is discussed.
Rapid Differential Determination of Mixtures of Hydrazine and Hydroxylamine by Potentiometric Titration with an Iodide Ion-selective Electrode
Authors: Motonaka Junko , Ikeda Sanae , Tanaka Nobuyuki 
Published: July 2006

Abstract
A rapid method has been established for determination of mixtures of hydrazine and hydroxylamine by potentiometric titration using an iodide ion-selective electrode. Accurate values are obtainable when nitric acid is added to the sample solution. A recommended procedure is proposed in which the sum of hydrazine and hydroxylamine is titrated with an aliquot of sample solution and another aliquot is titrated to the end point for hydrazine after hydroxylamine has been decomposed with nitric acid. Hydrazine and hydroxylamine in mixture can be determined in the concentration range of 0.01–0.5 mmol/dm3. The best result, with relative error and relative standard deviation both of less than 0.7%, may be obtained on 0.5 mmol/dm3 hydrazine and hydroxylamine.
Structure of Epilubimin, Epioxylubimin, and Isolubimin, Spirovetivane Stress Metabolites in Diseased Potato
Authors: Katsui Nobukatsu , Yagihashi Fujio , Murai Akio , Masamune Tadashi 
Published: July 2006

Abstract
The isolation and structure elucidation of the title spirovetivane sesquiterpenes, stress metabolites produced in diseased potato tubers, are described.
Synthesis and Reactions of o-Naphthothioquinone Methides
Authors: Okazaki Renji , Sunagawa Kazuhiko , Kotera Mitsuharu , Kang Kyung-Tae , Inamoto Naoki 
Published: July 2006

Abstract
Photochemical reactions of naphtho[1,2-c][1,2]dithiole-3-thione (7), naphtho[2,1-c][1,2]dithiole-1-thione (10), and naphtho[2,3-c][1,2]dithiole-3-thione (16) with cyclohexene and 2,3-dimethyl-2-butene afford the corresponding naphthothioquinone methides. The thioquinone methide from 7 exists only as a monomeric form and is the first isolable o-thioquinone methide, while that from 16 exists as a dimer of [4+4] type in the solid state although the chemical behavior suggests the presence of a monomeric form in solution to a very minor extent. In the case of the thioquinone methide from 10, there exists an equilibrium between a monomer and a dimer of [4+2] type. Some cycloadditions of these thioquinone methides are also described.
Synthesis of Paracyclo(1,8)napthalenophane and Paracyclo(5,6)acenaphthenophane
Authors: Kasahara Akira , Izumi Taeko , Shimizu Iwao , Satou Masahiro , Katou Takao 
Published: July 2006

Abstract
[2]Paracyclo[2]paracyclo[2](1,8)naphthalenophan-9-ene-1,17-diyne, [0]paracyclo[2]paracyclo[0](5,6)acenaphthenophan-7-ene, and [2]paracyclo[2]paracyclo[2](5,6)acenaphthenophan-9-ene-1,17-diyne, were synthesized by intramolecular reductive coupling reaction of the corresponding carbonyl compounds with low-valent titanium reagent. The structures of the compounds were elucidated by NMR analyses, and the transannular π-electronic interactions between two benzene rings were examined on the basis of electronic spectra.