bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potentiometric Studies on Sulfato Complex of Aluminium(III) in Aqueous Solution at Elevated Temperatures
Authors: Matsushima Yoshiyuki , Matsunaga Akio , Sakai Kazuhiro , Okuwaki Akitsugu 
Published: July 2006

Abstract
Equilibria in aluminium sulfate solutions with a 1 mol kg−1 KCl medium and low pH range have been investigated by means of acidity measurements with a hydrogen ion concentration cell from 25 to 125 °C. The results were treated with a nonlinear least squares computer program to analyze the equilibrium constants for aluminium complexes by using a single parameter type of Debye–Hückel equation. The log(K/mol−1 kg) values of the formation constant for the reaction, Al3++SO42−\ightleftarrows[AlSO4]+ varied from 3.35 at 25 °C to 5.34 at 125 °C and were formulated as a function of temperature. The standard enthalpy and entropy of the complex formation computed from the variation of the formation constant with temperature are presented over the experimental temperature range. The species [Al(SO4)2]− was not detected under the present conditions.
81Br NQR and 119Sn Mössbauer Study for MSnBr3 (M=Cs and CH3NH3)
Authors: Yamada Koji , Nose Sayuri , Umehara Takako , Okuda Tsutomu , Ichiba Sumio 
Published: July 2006

Abstract
Successive phase transitions were observed for CsSnBr3 and CH3NH3SnBr3 by means of 81Br NQR and DTA. These compounds are isomorphous with each other and have typical cubic perovskite structures at room temperature. However, with decreasing temperature both compounds showed successive phase transitions and complex 81Br NQR spectra at 77 K. In the case of CH3NH3SnBr3, both 81Br NQR and 119Sn Mössbauer spectra changed markedly with decreasing temperature from those at room temperature. These findings suggested a large distortion of the SnBr6 octahedron from the regular one and were interpreted on the basis of the three-center-four-electron bond model. In relation to these structural changes, a broad-line 1H NMR experiment on CH3NH3SnBr3 was also observed in order to determine the effect of the dynamic properties of the cation.
Study of Polarographic Anodic Wave in the Presence of Sulfate Ions by a Numerical Method
Authors: Kikuchi Kenji , Murayama Teisuke 
Published: July 2006

Abstract
A polarographic anodic wave in the presence of sulfate ions increases with any increase in the concentration of sulfate ions, contrary to the expectation based on a free dissolution of electrode mercury. It does not show any diffusion current plateau. The precipitation of mercury(I) sulfate, the product of an electrode reaction, does not take place within a dropping time. An analysis using a new numerical method previously reported proved that the wave is caused by the formation of a mercury(I) complex, [Hg2(SO4)], with a stability constant of 150 mol−1 dm3.
Reactivities of Stable Rotamers. XXIII. Some Addition Reactions toward the Vinyl Group in 9-(2-Vinyl-1-naphthyl)fluorene Rotamers
Authors: Oki Michinori , Tsukahara Jiro , Sonoda Yoriko , Moriyama Kazuhiro , Nakamura Nobuo 
Published: July 2006

Abstract
Addition reactions to the vinyl group of the ap and the sp rotamers of 9-(2-vinyl-1-naphthyl)fluorene were carried out. Whereas action of sulfuric acid on the sp rotamer caused a cyclization reaction, the ap isomer was recovered under the conditions. While addition of bromine afforded normal products for both the isomers, reaction of chlorine afforded chlorine-substituted products (chloro olefins) in addition to the normal adduct, the formation of the former being predominant, in the sp form. The slightly enhanced reactivity of the sp form relative to the ap in bromination together with the formation of the chloro olefin and the behavior of the sp form in the treatment with sulfuric acid are attributed to the stabilization of the intermediates by the π-participation of the fluorene ring. Other addition reactions, epoxidation, hydrogenation, hydroboration, osmium tetraoxide oxidation, chlorination with (dichloroiodo)benzene, and diimide reduction, which are believed to proceed through a cyclic transition state, have also been studied to show that the rates of the reactions of one isomer are not much different from those of another. Spectroscopic data suggest that the conformation of the vinylnaphthalene portion in both isomers are similar. Little difference in the reaction rates of the two rotamers are attributed to the possible transition state conformation which may not be affected by the steric hindrance of the fluorene ring.
Regioselective Ring Opening Reactions of 1-Aminocyclopropenes via Carbenium Ion and Carbene Intermediates
Authors: Yoshida Hiroshi , Sano Hiroe , Ogata Tsuyoshi , Matsumoto Kiyoshi 
Published: July 2006

Abstract
The reaction of 1-(disubstituted amino)-2,3-diphenylcyclopropenium salt with phenyl- and alkylmagnesium halides afforded, regioselectively, 1-aminocyclopropenes in good yields. The reactions of these 1-aminocyclopropenes were studied under acidic and nonacidic conditions to yield regioselective ring-opening products (C2–C3 and C1–C3 bond fissions of the cyclopropene) associated with the carbenium ions and carbene intermediates, respectively.
Synthesis and Absolute Configuration of the Acetalic Lignan (+)-Phrymarolin I
Authors: Ishibashi Fumito , Taniguchi Eiji 
Published: July 2006

Abstract
The natural (+)-phrymarolin I was stereoselectively synthesized and its absolute configuration was unequivocally determined as being (1S,2S,5R,6S)-1-acetoxy-2-(2-methoxy-4,5-methylenedioxyphenoxy)-6-(2-methoxy-4,5-methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octane.
Asymmetric Hydrocyanation of Aldehydes Using Chiral Titanium Reagents
Authors: Minamikawa Hiroyuki , Hayakawa Satoshi , Yamada Tohru , Iwasawa Nobuharu , Narasaka Koichi 
Published: July 2006

Abstract
Two highly enantioselective methods for hydrocyanation of aldehydes were developed by using chiral alkoxytitanium reagents. Treatment of benzaldehyde with cyanotrimethylsilane in the presence of a chiral alkoxytitanium affords mandelonitrile in good chemical and optical yields. By the use of the chiral cyanotitanium reagent generated in situ from the chiral alkoxytitanium and cyanotrimethylsilane, aliphatic aldehydes are converted into the corresponding cyanohydrins in a highly enantioselective manner.
Rechargeable Lithium Batteries Using Polypyrrole–Poly(styrenesulfonate) Composite as the Cathode-Active Material
Authors: Shimizu Atsushi , Yamataka Kazunori , Kohno Masashi 
Published: July 2006

Abstract
Polypyrrole–polyelectrolyte composite, obtained by electrochemical polymerization on a vapor-grown carbon fiber (VGCF) electrode, was used as a cathode-active material for a rechargeable lithium battery. Poly(styrensulfonate) ion was suitable as a dopant in terms of rechargeability of the battery. The VGCF, which has a fibrous structure, was effective as a current collector for the polymer electrode. The content of the dopant calculated by the molar ratio of sulfur and nitrogen was ca. 30%. The open-circuit voltage was 3.55 V at the time. A charge–discharge, accompanied by an Li+ deinsertion–insertion of the composite, was observed. The chargedischarge mechanism is similar to that of inorganic cathode-active materials that show Li+ intercalation. The battery was cycled stably beyond 30 times between 3.66 and 1.50 V at a constant current of 0.889 mA cm−2. An experimental capacity of 57 Ah kg−1 was obtained at the largest value on the basis of the weight of the active material. There is a possibility of developing a light-weight rechargeable battery using the polypyrrole–poly(styrenesulfonate) composite.
α,β-Unsaturated Nitriles in Heterocyclic Synthesis. Novel Synthesis of Pyridines and Thieno[2,3-b]pyridine Derivatives
Authors: Elgemeie Galal E H , Elfahham Hassan A , Nabey Hesham A 
Published: July 2006

Abstract
Arylmethylenecyanothioacetamide reacts with ethyl acetoacetate and acetylacetone to give the corresponding 3-cyano-2(1H)-pyridinethione derivatives, which can be alkylated at sulfur atom and cyclized into the corresponding thieno[2,3-b]pyridine derivatives.
Manganese “Picnic Basket” Porphyrins: Cytochrome P-450 Active Site Analogues
Authors: Collman James P , Brauman John I , Fitzgerald Jeffrey P , Hampton Philip D , Naruta Yoshinori , Michida Takashi 
Published: July 2006

Abstract
This paper describes studies of a new class of cytochrome P-450 model compounds called the “picnic basket porphyrins.” The picnic basket porphyrins are unsymmetrical porphyrins with one face sterically protected by a superstructure and the other unhindered. The manganese(III) porphyrins have been investigated as shape selective catalysts using oxygen atom donors in the presence of a sterically bulky imidazole. This paper presents ligand binding studies and competitive olefin epoxidations which lead to the surprising conclusion that catalysis by the manganese picnic basket porphyrins occurs exclusively on the sterically unhindered face indicating reaction by the minor catalyst component and not the selective major catalyst component.
Metal-Catalyzed Organic Photoreactions. Iron(III)-Catalyzed Photoreactions of Aldo- and Ketohexoses
Authors: Ichikawa Shuji , Tomita Isao , Hosaka Akira , Sato Tadashi 
Published: July 2006

Abstract
Under UV irradiation in the presence of iron(III) chloride or iron(III) triflate in pyridine, d-glucose, d-mannose, and d-galactose underwent a selective bond cleavage at the C1–C2 position, producing 4-O-formyl-d-arabinopyranose and 4-O-formyl-d-lyxopyranose. d-Fructose, under the same conditions, gave arabino-γ-lactone. The reaction was interpreted in terms of the photoinduced electron transfer within a chelate of iron ion with the carbohydrate molecule.
Optical Isomer Effect on the Mechanochemical Interaction of Mandelic Acid with Talc Powder
Authors: Ikekawa Akiko , Hayakawa Sohachiro 
Published: July 2006

Abstract
Mandelic acid was ball-milled with talc powder, and the optical isomer effect on the IR spectral change was investigated. The change showed that a complex was formed between talc and the hydroxyl group and the COOH group of mandelic acid. It was also shown that the covalent character in the bond of the C=O group with talc was greater for (RS)-mandelic acid than for the R-isomer and the S-isomer. The change in the region of the carbonyl-stretching vibration was affected by the humidity in the ball-milling atmosphere, and the effect on the R-isomer was greater than the effect on the S-isomer. Magnesium mandelate powder was obtained from an ethanolic suspension of the ball-milled mixture with talc. The IR spectra and the elemental analysis showed that the C=O group was covalently bonded to Mg in the complex of the (RS)-compound and that it was ionically bonded in the complex of the R-isomer and the S-isomer. The thermal analysis showed that the decomposition temperature for the complex of the R-isomer was different from the temperature for the complex of the S-isomer. It was suggested that talc powder had a chiral surface when it was mechanically treated.
Activated Nitriles in Heterocyclic Synthesis. Synthesis of Pyrimidine Derivatives
Authors: Sadek Kamal Usef , El-Maghraby Mohamed Abdallah , Selim Maghraby Ali , Elnagdi Mohamed Hilmy 
Published: July 2006

Abstract
Synthesis of polyfunctional pyrimidine derivatives via the reaction of acrylonitrile derivatives 1a and b with α,β-unsaturated nitriles 2a–f has been reported.
Kinetics of Oxidation of Aliphatic Ketones with Bromamine-T in Acid Medium
Authors: Mahadevappa Dandinasivara Siddalingaiah , Swamy Putta 
Published: July 2006

Abstract
The kinetics of oxidation of 2-propanone, 2-butanone, 2-pentanone, 3-pentanone, and 4-methyl-2-pentanone by sodium salt of N-bromo-p-toluenesulfonamide or bromamine-T (BAT) in presence of HClO4 was studied at 30 °C. The rate law is:
−\fracd[BAT]dt=k[BAT]0[ketone]1[H+]1.
Variation of ionic strength of medium or addition of reaction product p-toluenesulfonamide have no effect on the rate. The dielectric effect is positive. The acid-catalyzed enolization of ketone is assumed to be the rate-limiting step and enolization rate coefficients have been calculated. Proton inventory studies made in H2O–D2O mixtures have been employed to calculate the isotopic fractionation factors. Isokinetic temperature is 320 K indicating enthalpy as a controlling factor.
Counter Ion Effect on the 13C NMR Paramagnetic Relaxation Rate of Water–Methanol or Water–Dimethyl Sulfoxide Mixed Solvent with Ni(II) Solute
Authors: Kobayashi Kanya , Yokoi Masatoki , Kubota Eiji 
Published: July 2006

Abstract
The paramagnetic-salt induced 13C spinlattice relaxation rate of solvents methanol and dimethyl sulfoxide was measured for Ni(ClO4)2, NiSO4, and NiBDS (BDS: m-benzenedisulfonate) solutions in 50 wt.% mixture of each of the solvents and water. Relatively small relaxation rates were found for the solutions containing NiSO4. This fact is ascribed to the exclusion of some solvent molecules from the first coordination shell of Ni2+ due to the coordination of SO42− to Ni2+.
A BEDT-TTF Complex Including a Magnetic Anion, (BEDT-TTF)3(MnCl4)2
Authors: Mori Takehiko , Inokuchi Hiroo 
Published: July 2006

Abstract
The title charge-transfer complex is prepared and its crystal structure is determined (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene). One third of the BEDT-TTF molecules is incorporated in the anion sheet, and holds about 2+ charge. The remaining donors form a conducting sheet with a similar arrangement to β′-(BEDT-TTF)2ICl2.
Synthesis and Structure of cis(O,O),trans(N,N)-Chlorobis(8-quinolinolato-N1, O8)nitrosylruthenium
Authors: Kamata Yukiko , Miki Eiichi , Hirota Reiko , Mizumachi Kunihiko , Ishimori Tatsujiro 
Published: July 2006

Abstract
Molecular structure of the title compound has been determined by the X-ray diffraction. The Cl atom is in cis to the NO group, the O atom of one of the two quinolinolato ligands is in trans to the NO group, and the coordinating N and O atoms of two quinolinolato ligands are in cis(O,O) and trans(N,N) configuration.
Catalytic Asymmetric Cyclization of Some Bromohydrins with Chiral Cobalt Complex
Authors: Takeichi Tsutomu , Takakura Teruo , Ishimori Michihiro , Tsuruta Teiji 
Published: July 2006

Abstract
Asymmetric cyclization of a variety of bromohydrins with base was examined in the presence of an optically active cobalt(salen) type complex. Optically active oxiranes of modest optical purities were obtanied. erythro-3-Bromo-2-butanol and threo-3-bromo-2-butanol were cyclized similarly, and only trans-2,3-dimethyloxirane and cis-2,3-dimethyloxirane were obtained, respectively, indicating that the cyclization of bromohydrin proceeds by complete SN2 type reaction.
Formation of N,N′-Disubstituted Methanediamine Derivatives from Hexamethyldisilazane and Aldehydes via Stepwise Reactions
Authors: Nishiyama Kozaburo , Saito Masaki , Oba Makoto 
Published: July 2006

Abstract
The ZnCl2-catalyzed reaction of aldehydes with hexamethyldisilazane (HMDS) resulted in the formation of N,N′-disubstituted methanediamines, which were found to be formed stepwisely via 1 : 1- and 1 : 2-adducts of HMDS and aldehydes.
Mass Spectrometry of Molecular Adsorbates Using Laser Desorption/Laser Multiphoton Ionization
Authors: Zare Richard N , Hahn Jong Hoon , Zenobi Renato 
Published: July 2006

Abstract
Current and potential applications of a new mass spectrometric technique for the analysis of nonvolatile and thermally labile substances are reviewed. The method is compared to other approaches and its advantages are discussed.
Diene-Containing Lipids as Probes for Phase-Transition Behavior of Lipids in Liposomes
Authors: Takeoka Shinji , Iwai Hidetaka , Ohno Hiroyuki , Tsuchida Eishun 
Published: July 2006

Abstract
The absorption maximum (λmax) of 1,2-bis(2,4-octadecadienoyl)-sn-glycero-3-phosphorylcholine (DODPC), dispersed in an aqueous medium as liposomes, showed blue shift from 256.8 nm to 241.8 nm when these liposomes were cooled down from liquid crystalline state to gel state. The blue shift is explained to be due to stronger interaction between diene groups at gel state. This diene-containing lipid is examined to be an excellent membrane probe because it is typical phospholipid and miscible with several lipids. Furthermore, the dienoyl groups are known to be settled in the definite positions in bilayer membrane by suitable chemical modification. Phase transition behaviors of various 2,4-octadecadienoyl-containing phosphorylcholines as analogs for DODPC have also been investigated. Although they had similar spectral shifts at gel-to-liquid crystalline phase-transition temperature, their phase-transition temperatures and magnitude of λmax shifts were revealed to be related directly and therefore be governed by the different packing of the diene groups in bilayer membrane. DODPC was mixed with 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine, or cholesterol, and phase behaviors of these mixed liposomes were also examined. Phase-transition of the mixed liposomes was detected easily by the shift of its λmax with high sensitivity. Results were quite comparable to those obtained from other measurements, such as DSC, NMR, and so on.
Activation of Aromatic Carbon–Hydrogen Bonds by Palladium(II) Acetate–Dialkyl Sulfide Systems. Formation and Characterization of Novel Diphenyltripalladium(II) Complexes
Authors: Fuchita Yoshio , Hiraki Katsuma , Kamogawa Yasuko , Suenaga Miho , Tohgoh Kazutaka , Fujiwara Yuzo 
Published: July 2006

Abstract
Palladium(II) acetate reacts with benzene in the presence of dialkyl sulfides at 70 °C to afford novel diphenyltripalladium(II) complexes of [(R1SR2)PhPd(μ-MeCO2)2Pd(μ-MeCO2)2PdPh(R1SR2)] (1a; R1=But, R2=CH2But: 1b; R1=R2=Bui: 1c; R1=R2=Pri: 1d; R1=R2=Et). Adducts, [Pd(MeCO2)2(ButSCH2But)2] and [Pd(MeCO2)2(SPri2)2], prepared by the reactions of palladium(II) acetate and the corresponding dialkyl sulfides in benzene at 5–10 °C, change to 1a and 1c, respectively, on heating in benzene at 70 °C. In contrast, reactions of palladium(II) acetate with toluene or thiophene in the presence of diisopropyl sulfide afford no isolable tolyl-or thienyl-palladium species, but coupling products, i.e. bitolyls or bithienyls, are detected by GLC analysis. Treatment of 1b with styrene produces trans-stilbene, whereas 1c reacts with carbon monoxide as well as carbon dioxide to yield benzoic acid. When palladium(II) acetate and t-butyl phenethyl sulfide are heated at 80 °C in benzene, an adduct [Pd(MeCO2)2(ButSCH2CH2Ph)2] is formed, in sharp contrast with the case of benzyl t-butyl sulfide, which gives a cyclopalladated complex under the same reaction conditions.
Asymmetric Transformation of (RS)-Cysteine via Formation of (RS)-4-Thiazolidinecarboxylic Acids
Authors: Shiraiwa Tadashi , Kataoka Kazuo , Sakata Shinji , Kurokawa Hidemoto 
Published: July 2006

Abstract
Either (R)- or (S)-cysteine ((R)- or (S)-Cys) was efficiently obtained from (RS)-Cys by the asymmetric transformation via formation of (RS)-4-thiazolidinecarboxylic acid ((RS)-THC) or (RS)-2,2-dimethyl-4-thiazolidinecarboxylic acid ((RS)-DMT) and by using (2R,3R)- or (2S,3S)-tartaric acid ((R)- or (S)-TA), as a resolving agent, in acetic acid. The asymmetric transformation was carried out by combination of crystallization of less soluble salt of (S)-THC or -DMT with (R)-TA (or salt of (R)-THC or -DMT with (S)-TA) and epimerization of soluble diastereomeric salt. The (R)- and (S)-THCs from the less soluble salts gave approximately optically pure (R)- and (S)-Cys’s, respectively, in 64% yield. The asymmetric transformation via formation of (RS)-DMT was more successfully achieved by adding 0.1 molar equivalent of salicylaldehyde; that is, hydrolysis of the obtained less soluble salt gave optically pure (R)- and (S)-Cys’s, respectively, in 80% yield based on the (RS)-Cys used as the starting material.
Electrochemical Studies of Poly(mercaptohydroquinone) and Poly(mercapto-p-benzoquinone) Films Prepared by Electropolymerization. III. Basic Behavior and Properties in Aqueous Solutions
Authors: Arai Gorou , Shimamura Shigehiko , Ohtomo Yasunobu , Yasumori Iwao 
Published: July 2006

Abstract
Electrochemical behavior and properties of poly(mercaptohydroquinone)/poly(mercapto-p-benzoquinone)(SQ) films prepared on glassy carbon electrodes (GCE) by anodic polymerization of mercaptohydroquinone were examined in detail by cyclic voltammetry. Almost all hydroquinone and/or p-benzoquinone moieties in SQ films of less than ca. 100 monolayers are electroactive in acidic and neutral buffer solutions. The formal redox potential (as estimated from anodic and cathodic peak potentials) vs. solution pH plot, the slope of which is −60 mV/pH, suggests that the overall electrode reaction of SQ films is an H+/e (1:1) reaction. As to the voltammetric behavior of SQ films, the peak current decreased and the peak potential separaxtion (ΔEp) increased appreciably in unbuffered solutions as compared with those in buffered solutions. The difference of these voltammetric behaviors in unbuffered and buffered solutions increased with increasing pH. Moreover, the peak current increased and ΔEp decreased with rising solution temperature. These noticeable behaviors observed on SQ films are discussed in connection with the charge-transport mechanism within SQ films. SQ films on GCE showed good durability over a wide potential range from the hydrogen evolution potential to +1.0 V vs. SCE.
Host–Guest Complexation of Mono[6-(1-pyridinio)-6-deoxy]-α-cyclodextrin with Several Inorganic Anions
Authors: Matsui Yoshihisa , Fujie Masahiko , Hanaoka Kaori 
Published: July 2006

Abstract
Mono[6-(1-pyridinio)-6-deoxy]-α-cyclodextrin (1) formed 1:1 charge-transfer complexes with such inorganic anions as I−, SCN−, and Br− in an aqueous solution to afford characteristic UV absorption bands. The binding constant (Ka) for a I− complex with 1 was ca. 45 times as large as that with a nonmacrocyclic analog of 1, ca. 10 times that with native α-cyclodextrin, and 4.4 times that with a β-cyclodextrin analog. The I− ion was bound to a dipyridinio analog of 1 more strongly than to 1 by a factor of 10. The Ka values decreased with an increase in the ionic strength of the medium. The complexation was competitively inhibited by ClO4−. Hydrophobic, van der Waals, electrostatic, and charge-transfer interactions were supposed to take part in the complexation co-operatively.
Optical Resolution of 2′-Methoxy-1,1′-binaphthyl-2-carboxylic Acid, and Application to Chiral Derivatizing Agent for HPLC Separation of Enantiomeric Alcohols and Amines
Authors: Miyano Sotaro , Okada Shin-ichi , Hotta Hiroki , Takeda Masayuki , Kabuto Chizuko , Hashimoto Harukichi 
Published: July 2006

Abstract
Racemic 2′-methoxy-1,1′-binaphthyl-2-carboxylic acid was separated on a multi-gram scale into its antipodes via silica-gel column chromatography followed by alkaline hydrolysis of the diastereomeric esters prepared from (R)-1-phenylethanol or (−)-menthol. The molecular structure of (−)-menthyl (aS)-2′-methoxy-1,1′-binaphthyl-2-carboxylate was determined by single-crystal X-ray analysis. The (aS)-acid was converted to crystalline acid chloride, which was conveniently utilized as efficient chiral derivatizing agent for differentiation of enantiomeric alcohols and amines by high-performance liquid chromatography on silica gel. The elution behavior of a pair of diastereomeric esters or amides was explained by the steric interactions between the solutes and the silica-gel stationary phase on the basis of the X-ray analysis.