bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Heat of Immersion in Water and the Nature of the Surface Hydroxyl Group of Maghemite and Hematite
Authors: Watanabe Haruo , Seto Jun’etsu 
Published: July 2006

Abstract
The heats of immersion in water of maghemite (γ-Fe2O3) were measured in comparison to those of hematite (α-Fe2O3) prepared from the same maghemite by crystal transformation with heat treatment, and outgassing up to 200 °C. The heats of immersion and the heat of hydration of maghemite were lower than those of hematite throughout the measurement conditions. These differences were concluded to be due to the differences in bulk crystal structure, especially the density of the crystal. That is, the heat of hydration at the stage of physisorption depends on the surface hydroxyl group density, corresponding to the bulk crystal density. Also the surface hydroxyl groups are strongly affected by the polarization of the bonds in the bulk, this results in the difference of the heat of hydration at the stage of chemisorption (formation of the hydroxyl groups) and the acidity of the hydroxyl groups. This view is confirmed on the polymorphs of other metal oxides.
Novel Racemization of Atropisomeric Flavins and 5-Deazaflavins via Adduct Formation
Authors: Shinkai Seiji , Nakao Hideki , Yamaguchi Toshiro , Manabe Osamu 
Published: July 2006

Abstract
The molecular structures of covalent adducts derived from flavins and 5-deazaflavins are discussed on the basis of racemization of atropisomeric flavins and 5-deazaflavins. The 5-adducts with SO32− and CN− underwent facile racemization, indicating that the molecular structure changes from the “tense” planar state to the “relaxed” bent state. On the other hand, the 4a-adduct prepared by the photo-alkylation method did not racemize at room temperature. This indicates that the structure of the 4a-adduct is different from the bent 5-adduct. These results provide an information useful to discuss the reduced state of flavoproteins.
Topological Index and Thermodynamic Properties. IV. Size Dependency of the Structure-Activity Correlation of Alkanes
Authors: Gao Ying-duo , Hosoya Haruo 
Published: July 2006

Abstract
Correlation coefficients between twelve thermodynamic properties (ΔS, ΔHf, ΔGf, bp, d, nD, Rm, Vm, pc, Tc, Vc, dc) of 624 isomers of nonane through dodecane and five different topological indices (Z, p3, w, p2, A3) were calculated, where the new index A3 is proposed to be defined as the half sum of the off-diagonal elements of the cube of the adjacency matrix A. These properties can be classified into several types, according to the behavior of the two correlation coefficients, ρ(Z) and ρ(p3), against the change of the size of molecules. ΔS and bp depend largely on Z, while d and nD on p3, irrespective of the size change of molecules. On the other hand, ΔHf of smaller alkanes is largely dependent on Z, but for larger alkanes it turns out to be a p3-dependent property. Various interesting behaviors of the structure-activity relationships including the “pentane effect” were observed and discussed.
Study of Polarographic Anodic Wave in the Presence of Chloride Ions by a New Numerical Method
Authors: Kikuchi Kenji , Murayama Teisuke 
Published: July 2006

Abstract
A new numerical method is applied to the simultaneous diffusion equations describing the anodic process of mercury in solutions in the presence of chloride ions. The terms corresponding to precipitation and dissolution of mercury(I) chloride are included in the differential equations. It is found that the differential equation for precipitate particles should be rewritten using the backward space difference method for successful computation.
Structures of New [4+2]-Cycloadducts from Diels–Alder Reactions of Methyl 2-Oxo-2H-pyran-5-carboxylate with 2-Methyl- and 2-Methoxy-1,3-butadienes
Authors: Matsui Takanao , Kitajima Shinji , Nakayama Mitsuru 
Published: July 2006

Abstract
A Diels–Alder reaction of methyl 2-oxo-2H-pyran-5-carboxylate (1) with isoprene gave two stereoisomers, methyl 8-methyl-8-vinyl- and 8-isopropenyl-3-oxo-2-oxabicyclo[2.2.2]oct-5-ene-6-carboxylates. On the other hand, only a stereoisomer from a reaction of 1 with 2-methoxy-1,3-butadiene, methyl 8-methoxy-8-vinyl-3-oxo-2-oxabicyclo[2.2.2]oct-5-ene-6-carboxylate was obtained. The stereostructures of these adducts were determined by NMR spectral data and single-crystal X-ray analyses.
Stereochemical Behavior of Intermediary Compounds in the Amine-Catalyzed Knoevenagel Reaction
Authors: Tanikaga Rikuhei , Konya Naoto , Hamamura Kazumasa , Kaji Aritsune 
Published: July 2006

Abstract
Treatment of the active methylene compounds and aldehydes with a catalytic amount of a secondary amine produces thermodynamically stable alkenes, and the intermediary amino compounds are isolated. The reaction involves many reversible steps, and the stereochemistry of products is determined in the elimination step from the intermediary compounds via stable planar carbanions, in which the small difference in the steric requirements of two electron-withdrawing groups is effective. Steric and electronic effects in the intermediates sometimes bring about the carbon–carbon bond fission with recovery of active methylene compounds, and these effects prevent the Knoevenagel reaction from occurring.
Cobalt-Catalyzed Hydrohydroxymethylation of Formaldehyde: Effect of Ru3(CO)12 and Phenol
Authors: Murata Kazuhisa , Matsuda Akio , Masuda Takashi 
Published: July 2006

Abstract
A catalyst system, containing Co2(CO)8, Ru3(CO)12, and phenol, was found to be effective for the hydrohydroxymethylation of formaldehyde to give ethylene glycol with the yield of ca.65%, better than those previously reported.
The Catalytic Reduction of Aldehydes and Ketones with 2-Propanol over Hydrous Zirconium Oxide
Authors: Shibagaki Makoto , Takahashi Kyoko , Matsushita Hajime 
Published: July 2006

Abstract
Reduction of aldehydes with 2-propanol proceeded efficiently by catalysis with hydrous zirconium oxide to give the corresponding alcohols. Most ketones also were reduced efficiently, but conjugated or sterically hindered ketones resisted the reduction. The reduction was carried out with primary, secondary, or tertiary alcohols, and only secondary alcohols served as hydrogen donors. Kinetic experiments have indicated that the reaction rate is of first-order dependence on each of the concentrations of the carbonyl compound, 2-propanol, and the catalyst. An observation of the primary isotope effect has suggested that a step of hydride transfer from absorbed 2-propanol to absorbed carbonyl compound constitutes the rate-determining step for the reduction.
Simple Synthesis of (Z)-12-Nonadecen-9-one, (Z)-13-Icosen-10-one, the Sex Pheromone of Peach Fruit Moth, and (Z)-5-Undecen-2-one, a Biologically Active Molecule from the Pedal Gland of the Bontebok
Authors: Yamashita Masakazu , Matsumiya Kaoru , Murakami Kotomi , Suemitsu Rikisaku 
Published: July 2006

Abstract
A simple and convenient synthesis of (Z)-12-nonadecen-9-one, (Z)-13-icosen-10-one, the sex pheromone of the peach fruit moth, and (Z)-5-undecen-2-one, the pheromone from the pedal gland of the bontebok, is described. These pheromones were readily synthesized using successive alkylation of acetone dimethylhydrazone in one-pot.
An MO Study of Fragmentation Mechanism of Ethane and Propane Radical Cations
Authors: Osamura Yoshihiro , Takeuchi Takae , Nishimoto Kichisuke 
Published: July 2006

Abstract
The decomposition mechanisms were studied for ionized species of ethane and propane in the low-energy region by using an ab initio molecular orbital method. Calculations show that rather complex fragmentation processes may occur in addition to a simple cleavage of C–C and C–H bonds. In order to examine the possibility of an elimination of H2 or CH4 from the radical cation of saturated hydrocarbons, the potential energy curves were calculated for both 1,1- and 1,2-eliminations. An energy barrier of 1,2-elimination was estimated to be small, but a 1,1-elimination can also possibly occur. It was also found that a single C–H bond scission of the parent radical cation may occur with the same order of energy for the H2 loss. The present results are qualitatively in a good agreement with the experiments.
The Preparation of Colloidal Precious Metal Particles Using Copolymers of Vinyl Alcohol–N-Vinylpyrrolidone
Authors: Meguro Kenjiro , Nakamura Yukari , Hayashi Yoshihiro , Torizuka Makoto , Esumi Kunio 
Published: July 2006

Abstract
Precious metal particles of platinum and silver have been prepared by the reduction of metal salts dissolved in an aqueous solution of a copolymer of vinyl alcohol and N-vinylpyrrolidone with methanol. The stable platinum sols were obtained in the presence of poly(vinyl alcohol), poly(N-vinylpyrrolidone), and their copolymers, but their particle sizes hardly changed with the ratio of N-vinylpyrrolidone in the copolymer. On the other hand, colloidal stable silver sols were obtained only in the presence of a copolymer. Further, with an increase in the ratio of N-vinylpyrrolidone in the copolymer, the particle size of silver became small.
Cobalt(III) Complexes Containing an Aldonic Acid
Authors: Tsubomura Taro , Yano Shigenobu , Yoshikawa Sadao 
Published: July 2006

Abstract
Stable complexes of the type [Co(aldonato)(en)2]+, where en is ethylenediamine and aldonato is the diacid anion of d-gluconic acid or l-mannonic acid, were prepared by the reaction of aldonic acid lactones with rac-[Co(CO3)(en)2]+. Two diastereomers (Δ and Λ) have been separated by ion-exchange chromatography from each of the aldonato complexes. These complexes were characterized by NMR, electronic absorption, and circular dichroism spectra. The structures of all four complexes were found to have an aldonato ligand which coordinates bidentately through an oxygen atom of the carboxylato group and an oxygen atom of the deprotonated hydroxyl group on C(2).
Photochemical Fatigue Resistances and Thermal Stabilities of Heterocyclic Fulgides in PMMA Film
Authors: Kaneko Akira , Tomoda Akihiko , Ishizuka Mitsuo , Suzuki Hisao , Matsushima Ryoka 
Published: July 2006

Abstract
Thermal stabilities of the colored forms at 80°C and photochemical fatigue resistances against coloration–discoloration cycles were measured in PMMA thin film, using 14 derivatives of fulgide with different heterocyclic structures. The indolyl (12), oxazolyl (13), and thiazolyl (14) derivatives showed very low thermal degradabilities (TD≤1.5%/day) while 12 and pyrazolyl derivative (9) showed low photochemical fatigues (PF≤0.2%/cycle), as compared with the furyl (1), thienyl (2), and pyrrolyl (3) derivatives. However, many of them featured low photo-responsiveness and low absorptivities for coloration on UV irradiation.
A Consideration of the Charge Density of Polyelectrolytes Based on a Layer Model in Solution
Authors: Kaneko Tetsuo 
Published: July 2006

Abstract
In a model system where layers formed by aggregations of polyelectrolyte molecules are mutually parallel in a solvent, the surface-charge density of the layers is estimated by solving the one-dimensional Poisson–Boltzmann equation. The surface-charge density at a over temperature, T, can be determined depending on the number, ng, of charged groups per unit of the volume in a layer of polyelectrolytes and on the thickness, Δx, of the layer, if the distance between layers of polyelectrolyts is sufficiently large. This surface-charge density is evaluated by assuming that ng is given by the reciprocal of the cubed mean length between neighboring charged groups in a polyelectrolyte molecule and that Δx is of the order of an ion diameter, possibly including the hydration sheath. The surface-charge density given by the layer model agrees well with that semiempirically given by a rod-like polyelectrolyte model. Also, the ratio of the total charge of a layer to the total charge of the charged groups in the layer agrees well with the degree of the ionic dissociation of ionene polymers in a salt-free solution.
General Reactivity of 2-Lithiobenzothiazole to Various Electrophiles and the Use as a Formyl Anion Equivalent in the Synthesis of α-Hydroxy Carbonyl Compounds
Authors: Chikashita Hidenori , Ishibaba Megumi , Ori Keiji , Itoh Kazuyoshi 
Published: July 2006

Abstract
The reaction of 2-lithiobenzothiazole with a variety of electrophiles such as aldehydes, ketones, carboxylic esters, lactones, nitriles, and amides afforded the expected addition and substitution products. Trimethylsilyl chloride readily reacted with the benzothiazolyl anion to give 2-trimethylsilylbenzothiazole, while common alkyl halides including primary iodide and benzyl halides, as well as epoxides, did not react with the anion. This characteristic nucleophilicity of the anion was also demonstrated by its reaction with phenacyl halides and 5-chloro-2-pentanone leading to the formation of benzothiazolyl-substituted small-ring ethers. In order to demonstrate the value of 2-lithiobenzothiazole as a masked formyl anion, 2-(α-hydroxyalkyl)benzothiazoles were transformed into α-hydroxy carbonyl compounds in three reaction steps without masking the α-hydroxy groups. Quaternization of various 2-(α-hydroxyalkyl)benzothiazoles with methyl iodide in DMF afforded the corresponding 2-(α-hydroxyalkyl)-3-methylbenzothiazolium iodides in high yields and the subsequent alkylation or reduction of the C=N+ link was readily accomplished with organolithium and Grignard reagents or sodium borohydride leading to the corresponding 2-(α-hydroxyalkyl)-3-methylbenzothiazolines with or without another 2-substituents. Hydrolysis of former compounds performed in aqueous acetonitrile, buffered to pH 7 and containing AgNO3, gave the desired α-hydroxy ketones.
Solution Structure and Preferred Orientation of 3,7-Dibromo-10H-phenothiazine Dissolved in Nematic Liquid Crystal
Authors: Fujiwara Hideaki , Watanabe Masayuki , Yamanaka Iwao , Takagi Tatsuya , Sasaki Yoshio 
Published: July 2006

Abstract
The NMR spectrum of the title compound has been measured in nematic phase ZLI1167 and analyzed to obtain the direct couplings. The direct couplings were interpreted by assuming a folded structure of the tricyclic framework. The dihedral angle of the two phenyl rings is determined to be 149.1±2.5° and a value of 170±3° is obtained for the angle of S···N–H. The NH proton is concluded to occupy a “equatorial” position on the central ring in a boat form. The preferred orientation of the molecule in ZLI1167 is discussed by comparing the principal axes of order tensor with those of the moment of inertia.
Antimony(V) Arsenatophosphate as a Thermally Stable Cation Exchanger: Selective Adsorption of Alkaline Earth and Transition Metal Ions on Its Column
Authors: Varshney K G , Khan A A , Khan A R 
Published: July 2006

Abstract
A new inorganic ion exchanger based on antimony has been prepared viz. antimony(V) arsenatophosphate, which has shown a peculiarly high thermal stability and selectivity for alkaline earth and transition metal ions. As a result, its column use has been demonstrated for the separation of mercury from magnesium and zinc and of iron from other transition metals. A tentative formula has also been proposed for the material, on the basis of its chemical analysis and other characterization studies.
Organophosphorus Analogues and Derivatives of the Natural l-Amino Carboxylic Acids and Peptides. I. Enzymatic Synthesis of d-, Dl-, and l-Phosphinothricin and Their Cyclic Analogues
Authors: Natchev Ivan A 
Published: July 2006

Abstract
Acetylation of d-, Dl-, and l-3-amino-2-pyrrolidinone (1) to the 3-acetamido derivative 2 and treatment with ethyl methylphosphinate afforded the addition product 3. Strict selectivity was observed in the enzyme-catalyzed hydrolysis with the enzyme phosphodiesterase I, acylase, glutaminase, and α-chymotrypsin. The ester 7 and 1,2-azaphospholidine (8) were isolated by esterification of l-phosphinothricin (6).
The Valence Control and Catalytic Properties of La2−xSrxNiO4
Authors: Nitadori Taihei , Muramatsu Motohiko , Misono Makoto 
Published: July 2006

Abstract
A series of La2−xSrxNiO4 catalysts (x=0–1.0) with a K2NiF4-type structure were prepared, and the average oxidation number of the Ni ion and the stoichiometry of the oxygen in the catalysts were measured. We also investigated the relationships between the reactivity of the catalysts and their catalytic activity for oxidation. The average oxidation number of the Ni ion increased monotonously from 2.32 (x=0) to 2.90 (x=1.0) upon the Sr substitution, and the composition changed with the x value from oxygen-excess (x=0–0.2) to oxygen-deficient (x=0.6–1.0), via a stoichiometric composition at x=0.4. In the range of x=0–0.2 (oxygen excess), the desorption peaks of oxygen in TPD (temperature-programmed desorption) were observed at about 300 °C; these results were ascribable to the excess oxygen. In this range, the oxidizing power of the surface, which was measured by the reduction of the catalysts by CO, was comparatively high. For x=0.4–1.0 (stoichiometric to oxygen-deficient), the oxygen desorbed at a higher temperature, and the amounts increased in accordance with the increase in the oxygen deficiency. The oxidizing power of the surface similarly increased with x values up to x=0.8. The composition of metal on the surface generally reflected that in the bulk, as judged from XPS. The catalytic activity for the oxidation was in parallel with the oxidizing power of the surface in x=0.4–1.0.
Liquid Structure of N,N-Dimethylformamide, Acetonitrile, and Their 1 : 1 Molar Mixture
Authors: Radnai Tamas , Itoh Sumiko , Ohtaki Hitoshi 
Published: July 2006

Abstract
Liquid structures of pure N,N-dimethylformamide (DMF) and acetonitrile (AN) as well as of their 1 : 1 molar mixture were investigated by X-ray diffraction at 25 °C. The careful reinvestigation of pure DMF led to a good reproducibility of the previous result. Slight deviations in the structural parameters are discussed and a detailed parameter table is reported. A simple model in which each AN molecule has 2 neighbors at an average distance of 330 pm describes the more ordered first neighbor structure of pure AN. The main interaction forming the structure is of dipole–dipole type, in agreement with previous findings. In the 1 : 1 molar mixture a dipole–dipole model also leads to a satisfactory description of the first neighbor structure. The preferred orientation is that with dipoles in the antiparallel position. A central DMF molecule has 1.75 neighboring AN molecules in average at a distance of 316 pm. The same stands for DMF around AN. No evidence for other kinds of interaction, e.g., weak H-bond type intermolecular interactions could be found in the mixture.
The Synthesis and Thermal Behavior of Lithium cyclo-Hexaphosphate
Authors: Watanabe Makoto , Murata Khoichi , Maeda Mioko 
Published: July 2006

Abstract
Lithium cyclo-hexaphosphate hexahydrate was made by heating a mixture of 85%-phosphoric acid and dilithium carbonate at an Li/P molar ratio of 1.4 at 200 (1 h), 275 (5 h), and then 420 °C (3 h). The thermal product was handled with a wet chemical method developed in this study. The cyclo-hexaphosphate was stable at room temperature (20–30 °C), while a small part of it decomposed to phosphates with shorter chain lengths above about 60 °C in air. The cyclo-hexaphosphate was transformed thermally to crystalline long-chain polyphosphates upon heating above 530 °C.
Footprint Catalysis. II. Molecular Recognition of Footprint Catalytic Sites
Authors: Morihara Kensaku , Nishihata Emiko , Kojima Mari , Miyake Sayoko 
Published: July 2006

Abstract
In order to investigate the molecular recognition capability of “footprint” catalytic sites, the affinities of nine “footprint” catalysts for eleven competitive inhibitors, closely related to template molecules, were estimated through the competitive inhibition constants, Ki. An examination of the affinity revealed that the recognition by “footprint” catalytic sites was so highly specific that it could recognize not only the whole, but also the partial, structures of the bound molecules.
The pH Titration Study of Lithium Ion Adsorption on λ-MnO2
Authors: Ooi Kenta , Miyai Yoshitaka , Katoh Shunsaku , Maeda Hiroshi , Abe Mitsuo 
Published: July 2006

Abstract
The pH titration curves of λ-MnO2 showed apparently dibasic acid character toward Li+ ions, but a monobasic acid character toward Na+, K+, Rb+, and Cs+ ions. The adsorptive capacities of alkali metal ions increased in the order; K+, Rb+, Cs+&lt;Na+&lt;&lt;Li+ at pH 10. Overall equilibrium constants were calculated by a simplified Gaines-Thomas equation from the titration curves based on the ion-exchange mechanism. Thermodynamic data were derived for the system of (0.1-M LiCl+LiOH)(1 M=1 mol dm−3) at different temperatures. Effects of ionic strength and adsorption temperature on the lithium ion adsorptivity were studied using (LiCl+LiOH) and (KCl+LiOH) solutions.
Decalino-14-crown-4. New Type of Lithium Ion Selective Ionophore
Authors: Kobiro Kazuya , Hiro Toshitaka , Matsuoka Toshihiro , Kakiuchi Kiyomi , Tobe Yoshito , Odaira Yoshinobu 
Published: July 2006

Abstract
A new type of crown ether, decalino-14-crown-4, has been synthesized and found to be a highly selective and effective ionophore for lithium ion.
A Determination Method of Absolute Configuration
Authors: Toda Fumio , Mori Koji , Sat\={o} Atsushi 
Published: July 2006

Abstract
A determination method of absolute configuration of sulfoxides, amines, and aminoalcohols by measuring their 1H NMR spectra in the presence of optically active 2,2′-dihydroxy-1,1′-binaphthyl and 1,6-di(o-chlorophenyl)-1,6-diphenyl-2,4-hexadiyne-1,6-diol, was reported.
Synthesis and Properties of 4H-Benzo[hi]pyrrolo[2,1,5-cd]indolizin-4-ones
Authors: Noguchi Michihiko , Yamamoto Takashi , Kajigaeshi Shoji , Saito Keiji , Arai Tsuyoshi 
Published: July 2006

Abstract
3-Phenyl-4H-benzo[hi]pyrrolo[2,1,5-cd]indolizin-4-one (5) was prepared by saponification accompanied by the decarboxylation of the corresponding 1,2-bis(methoxycarbonyl) derivative, which was obtained by the DDQ oxidation of 5,6-dihydro one. Investigations concerning its spectral data and MO calculations revealed interesting electronic features for 5, e.g., i) a highly polarized structure in the ground state, ii) the exsistence of a peripheral [12]annulene system in acidic media, and iii) a significant stabilization of the excited state by protonation.
Possibility of Superconducting and Other Phases in Organic High Polymers of Polyacene Carbon Skeletons. I. Screened Electron–Electron Interaction—Random Phase Approximation—
Authors: Kimura Minoru , Kawabe Hiroyuki , Nakajima Akihiko , Nishikawa Kiyoshi , Aono Shigeyuki 
Published: July 2006

Abstract
The effective electron–electron interaction in the high polymers of polyacene carbon skeleton is investigated. The appearance of various phases in this system depends on associated parameters characterizing the electron–electron interactions near the Fermi level. The main purpose of this work is to estimate these parameters under the random phase approximation and to presume whether this polymer may or may not be superconductor at room temperature.
Possibility of Superconducting and Other Phases in Organic High Polymers of Polyacene Carbon Skeletons. II. Screened Electron–Electron Interaction —Method of Renormalization Group—
Authors: Kimura Minoru , Kawabe Hiroyuki , Nishikawa Kiyoshi , Aono Shigeyuki 
Published: July 2006

Abstract
The electron–electron interaction which is crucial in determining whether new phases will arise or not in polyacene is investigated by means of the renormalization group. This approach is valuable to effectively include, from the view-point of the group theory, the higher order diagrams not taken into account in the random phase approximation of the previous work. It is found that there is a range of coupling constants where the singlet superconducting phase without simultaneous CDW ordering can be expected.