bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basic Autoxidation of Friedelin
Authors: Nishihama Tadaaki , Takahashi Takeyoshi 
Published: July 2006

Abstract
Base-catalyzed autoxidation of a triterpene ketone, friedelin, in the presence of potassium t-butoxide gave four products, and their structures and formation mechanism were investigated. The common intermediate to these compounds was suggested to be 4-hydroperoxyfriedelan-3-one, not friedelane-2,3-dione. 3-Oxafriedel-1-ene-2-carboxylic acid was a dehydration product of the main product, 2-hydroxy-3-oxafriedelane-2-carboxylic acid.
Kinetic Studies of Antioxidant Activity of New Tocopherol Model Compounds in Solution
Authors: Mukai Kazuo , Yokoyama Satoshi , Fukuda Kazuyuki , Uemoto Yuichi 
Published: July 2006

Abstract
The second-order rate constants ks for the reaction of 10 kinds of tocopherol (vitamin E) model compounds with stable phenoxyl radical in ethanol have been measured at 25.0°C, using a stopped-flow spectrophotometer, as a model reaction of tocopherols with unstable free radicals (ROO·, RO·, and HO·) in biological systems. The absolute ks values of α-, β-, γ-, and δ-tocopherol models are similar to or slightly smaller than those of the corresponding tocopherols having a long-phytyl-chain. The relative ks values (α: β: γ: δ=100 : 53 : 50 : 24), that is, relative antioxidant activities, of α-, β-, γ-, and δ-tocopherol models are in good agreement with those (100 : 44 : 47 : 20) of α-, β-, γ-, and δ-tocopherols. The antioxidant activities of tocopherol models having two alkyl substituents, such as methyl, ethyl, isopropyl, and t-butyl groups, at ortho positions of OH group are similar to each other, suggesting that the effect of steric hindrance on the reaction rate is small. 5,7-Dimethyltocol model has quite similar rate constants with those of β- and γ-tocopherol models, whereas δ-tocopherol model is only ca. 24% as reactive as α-tocopherol model and tocol model is only ca. 10% as reactive as α-tocopherol model. The result indicates that the rate constants increase as the total electron donating capacity of the alkyl substituents at aromatic ring increases. For the tocopherol models logks was found to correlate with Σσ+ substituent constants with a ρ+ value of −1.0.
Electrogenerated Acid-Catalyzed Reactions of Acetals, Aldehydes, and Ketones with Organosilicon Compounds, Leading to Aldol Reactions, Allylations, Cyanations, and Hydride Additions
Authors: Torii Sigeru , Inokuchi Tsutomu , Takagishi Sadahito , Horike Hirofumi , Kuroda Hideki , Uneyama Kenji 
Published: July 2006

Abstract
Exquisite use of electrogenerated acid (EG acid) in the silicon-mediated acid-catalyzed reactions; e.g., aldol reactions, allylations, cyanations, and hydride additions is described. The aldol reaction of acetals 1 with enol trimethylsilyl ethers 3 and 1,2-bis(trimethylsiloxy)alkenes 4 gives the corresponding adducts 5 and 6, respectively. The reaction proceeds smoothly with EG acid derived from perchlorate salts such as LiClO4, n-Bu4NClO4, and Mg(ClO4)2 in dichloromethane using platinum electrodes. The amount of electricity required to complete the reaction implies a cationic process which is mediated by the trimethylsilyl moiety. This aldol reaction is further developed with unprotected carbonyl compounds 2 with 3, giving the trimethylsilyl ethers of the adducts 7. Further utility of this EG acid as a catalyst for a chain reaction is exemplified by the successful application in the following conversions: (1) The allylation of acetals 1 with allyltrimethylsilane (8) to give 9, (2) the cyanation of acetals 1 and unmasked 2 with trimethylsilyl cyanide (10) to give 11, 12, and 13, and (3) the hydride addition of acetals 1 with triethylsilane (14) to give 15.
Studies on Dissolved Metalloenzymes in Lake Water. III. Correlation between Dissolved Alkaline Phosphatase and Orthophosphate in Lake Water
Authors: Kobayashi Kensei , Iwase Kimikazu , Hashimoto Shinya , Ueda Hirotaka , Fujiwara Kitao , Otsuki Akira , Fuwa Keiichiro , Haraguchi Hiroki 
Published: July 2006

Abstract
Alkaline phosphatase activity (both dissolved and total) in Lake Kasumigaura was determined periodically together with concentrations of phosphorus compounds therein. Distinct negative correlation was found between the dissolved alkaline phosphatase activity and the orthophosphate concentration during the phosphorus-limited season. The decrease of the concentration of dissolved alkaline phosphatase was observed at the level of 1 ng ml−1 of orthophosphate. The present results suggest that both alkaline phosphatase in vivo and dissolved alkaline phosphatase in the lake water play important roles in phosphorus cycles in natural water.
Geochemical Characterization of Geological Standard Rock Samples from Rare Earth Element Distribution Patterns Measured by Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Toyoda Kazuhiro , Haraguchi Hiroki 
Published: July 2006

Abstract
Rare earth elements (REEs) in twelve standard rock samples have been determined by inductively coupled plasma atomic emission spectrometry after separation of diverse metal ions with cation exchange resin. These rock samples are old six standard rocks (W-1, BCR-1, AGV-1, GSP-1, JB-1, JG-1) and new six standard rocks (JB-2, JB-3, JA-1, JR-1, JR-2, JGb-1) issued from the Geological Survey of Japan. These samples are various types of igneous rocks, which show various shapes of the REE distribution patterns. Geochemical characteristics of these standard rock samples will be discussed from the relationships between rock types and the shapes of the REE pattern.
27Al NMR Study on the Interaction between Aluminate and Silicate Ions in Alkaline Solution
Authors: Yokoyama Takushi , Kinoshita Setsuko , Wakita Hisanobu , Tarutani Toshikazu 
Published: July 2006

Abstract
An interaction between aluminate and silicate ions in highly alkaline solution was investigated by a high-resolution 27Al NMR study. The interaction greatly varied with alkali concentration, and did not occur at 1.0 mol dm−3 NaOH. At 0.10 mol dm−3 NaOH, the formation of a monomeric species with an ≡Al–O–Si≡ bond (Si/Al=1) was suggested and the formation constant was estimated to be 22.8 dm3 mol−1. At 0.015 mol dm−3 NaOH, polynuclear species with ≡Al–O–Si≡ bond was expected to be formed.
Convenient Optical Resolution of Axially Chiral 1,1′-Binaphthyl-2,2′-dicarboxylic Acid
Authors: Kanoh Shigeyoshi , Hongoh Yukihiko , Motoi Masatoshi , Suda Hiroshi 
Published: July 2006

Abstract
Axially chiral 1,1′-binaphthyl-2,2′-dicarboxylic acid was conveniently resolved through its brucine salts in satisfactory yields. The resolved diacids were confirmed to be optically pure from high-performance liquid chromatographic analyses of the dimethyl esters derived from them on an optically active poly(diphenyl-2-pyridylmethyl methacrylate) column.
Palladium-Catalyzed Double-Carbonylation of Alkenyl Halides with Secondary Amines To Give α-Keto Amides
Authors: Son Tae-il , Yanagihara Hisayoshi , Ozawa Fumiyuki , Yamamoto Akio 
Published: July 2006

Abstract
The double-carbonylation reaction of alkenyl halides with diethylamine in the presence of palladium catalysts has been examined in detail. The reaction gives α-keto amide together with amide, the single-carbonylation by-product. The yield of α-keto amide is strongly dependent on the nature of alkenyl halide. Alkenyl bromides or iodides having phenyl group(s) as substituent(s) on the vinyl group are successfully double-carbonylated under appropriate reaction conditions and the corresponding α-keto amides are obtained in good to modest yields together with amides. In contrast, the reactions of alkenyl halides without a phenyl group give amides exclusively. In order to clarify the reason for the substrate-specificity in the reaction, series of alkenyl- and alkenoylpalladium(II) complexes, the presumed intermediates in the catalytic reactions, have been prepared and their reactions with secondary amines, carbon monoxide, and alkenyl halides were examined. The study suggests the operation of three types of processes for amide formation in the catalytic reactions. Possible mechanisms for amide as well as α-keto amide formation are discussed.
Sorption of Uranyl Ions on Hydrous Oxides. A New Surface Hydrolysis Model
Authors: Gupta Anand Ram , Venkataramani Balakrishnan 
Published: July 2006

Abstract
Sorption of uranyl ions on hydrous titanium oxide(HTiO), magnetite(MAG), and hydrous thorium oxide(HThO) has been studied as a function of pH. Hydrous oxides have been characterized by their pH-titration curves, intrinsic dissociation constants(pKai*) and point of zero charge (pHpzc). The fraction of protonated surface hydroxyl groups as well as the surface pH(pHsurf) as a function of solution pH have been computed. The distribution of various hydrolyzed species of uranyl ions with solution pH have been compared with uranyl sorption isotherm on these oxides. Sorption edge in all the cases occurs when free hydroxyl groups are available on the surface and pHsurf is sufficiently high to favor the formation of dimer-like species on the surface. A new model for the sorption process, called surface hydrolysis model, which explains these and other features of uranyl sorption on hydrous oxides has been proposed. The model visualizes the sorption process as linking of uranyl ions with two adjacent free surface hydroxyl groups without deprotonation (provided the surface pH is high for the hydrolysis of uranyl ions) and formation of dimer-like structures on the surface. The new model has been successfully applied to the present and other available data on uranyl ion sorption on hydrous oxides.
Synthesis of 1,2,5a-Triazacyclohept[a]azulen-5(2H)-ones
Authors: Abe Noritaka , Emoto Yoshifumi 
Published: July 2006

Abstract
Reactions of 2-hydrazino-1-azaazulenes with acetylacetone gave 2-(3,5-dimethyl-1-pyrazolyl)-1-azaazulenes. Cyclizations of diethyl (1-azaazulen-2-yl)hydrazinomethylenemalonates in refluxing t-butylbenzene or on silica gel gave 1,2,5a-triazacyclohept[a]azulen-5(2H)-ones.
Molecular and Crystal Structure of the Lipid-Model Amphiphile, Dioctadecyldimethylammonium Bromide Monohydrate
Authors: Okuyama Kenji , Soboi Yoshie , Iijima Naomi , Hirabayashi Kiyoshi , Kunitake Toyoki , Kajiyama Tisato 
Published: July 2006

Abstract
Dioctadecyldimethylammonium bromide monohydrate (2C18N+2C1Br−·H2O), C38H80NBr·H2O, was crystallized from its solution in chloroform and hexane. The crystals are triclinic with the space group P\bar1, Z=2, a (normal to the bilayer surface)=3.811(2), b=0.7890(2), c=0.7418(2) nm, α=104.37(3), β=103.06(4), and γ=74.93(3)°. The structure was solved by the direct method and refined by the block-diagonal least-squares procedure: R=0.08 for 3121 observed reflections. The crystal structure consists of bimolecular layers stacking regularly along the a-direction. The two amphiphile molecules in the unit cell are related by centrosymmetry and pack tail to tail in a bilayer structure with tilting hydrocarbon chains by about 45° to the bilayer surface. The packing cross section per molecule in the layer plane is 0.567 nm2. The hydrocarbon chains pack with an triclinic (T//) subcell with dimensions of as=0.42, bs=0.49, cs=0.26 nm, αs=88, βs=104, and γs=111°. One of the two alkyl chains bends near the nitrogen atom and conforms a part of a head region. Two water oxygen atoms with half occupancies were found in an asymmetric unit and accomodated statistically in a unit cell. These water molecules are linked with bromide anions by hydrogen bonds with the distance of about 0.34 nm. Bromide anions and ammonium cations are on the same plane parallel to the bilayer surface.
Study of Ion Transport across Amphoteric Ion-Exchange Membrane. V. Nonequilibrium Thermodynamic Analyses of Ion Selectivity
Authors: Kaibara Kozue , Inoue Hiroyoshi , Tsuruyama Shigeru , Kimizuka Hideo 
Published: July 2006

Abstract
Ion-transport processes across an amphoteric ion-exchange membrane were investigated by means of estimating the membrane permeability matrix, a set of modified linear phenomenological coefficients, from the electrochemical and the ion flux data. Systematic comparisons of phenomenological analyses on an amphoteric ion-exchange membrane system with those on an ordinary cation-exchange membrane system were carried out to investigate the correlations of singly- and binary-charged membrane structures to characteristic transport properties. The modes of ion permselectivity of an amphoteric ion-exchange membrane in the metal chloride concentration-cell systems are characterized by the potentiometric selective response due to the ion-sieve effect, the low membrane conductance, and the large ion flux, while those of an ordinary cation-exchange membrane are characterized by the totally charge-dependent potential response, the high conductance, and the extremely small ion flux. The cross elements of the membrane permeability matrix, which represent the partial contributions of cation-anion interactions to the membrane permselectivity, are positive for an amphoteric membrane and negative for a cation-exchange membrane. The positive cross matrix elements act deceleratively on the membrane permeability, whereas the negative elements do acceleratively. It was pointed out based on the nonequilibrium thermodynamic theory that the preferable and efficient permeation mechanism is the simple diffusion process in an amphoteric ion-exchange membrane, whereas the electroconductive process in a cation-exchange membrane.
H2 Evolution from Various Aqueous Solutions over Thermally Reduced TiO2 and Pt–TiO2 Powder
Authors: Kudo Akihiko , Domen Kazunari , Maruya Ken-ichi , Onishi Takaharu 
Published: July 2006

Abstract
The reduction of H2O (or H+) to form H2 by reduced TiO2 and Pt–TiO2 was studied in distilled water and aqueous solutions of HCl, H2SO4, HNO3, and NaOH. Over the reduced TiO2 powder, H2 evolved moderately in distilled water and Ti3+ ions on the surface were presumed to be active sites for the reaction. The reaction in aqueous NaOH solution proceeded similarly to that in water while it was strongly suppressed in aqueous HCl and H2SO4 solutions. It was found that the suppression of H2 evolution is due to protons in the solution. Over reduced Pt–TiO2, H2 evolved rapidly from all solutions, except HNO3. In aqueous HNO3 solution, NO3− was reduced to NH3 over reduced TiO2 and Pt–TiO2.
Preparation and Characterization of (Tetrabenzoporphyrinato)nickel Hexafluoroarsenate, (NiTBP)3(AsF6)2(C10H7Cl). A New Type of Metallomacrocyclic Radical Salts
Authors: Yakushi Kyuya , Yoshitake Michiko , Kuroda Haruo , Kawamoto Atsushi , Tanaka Jiro , Sugano Tadashi , Kinoshita Minoru 
Published: July 2006

Abstract
Single crystals of a (tetrabenzoporphyrinato)nickel hexafluoroarsenate, (NiTBP)3(AsF6)2 were prepared by the use of an electrochemical technique. NiTBP is stacked one-dimensionally with a periodic unit composed of three macrocycles. This stacking mode is a new type among the one-dimensionally stacked macrocyclic complexes. The experimental results on reflectance spectrum and ESR indicate that this material is a one-dimensional semiconductor with a small electron correlation.
Structural Requirements for the Spatial Structure and Toxicity of Heat-Stable Enterotoxin (STh) of Enterotoxigenic Escherichia coli
Authors: Yamasaki Shinji , Hidaka Yuji , Ito Hideaki , Takeda Yoshifumi , Shimonishi Yasutsugu 
Published: July 2006

Abstract
The heat-stable enterotoxin (STh) of enterotoxigenic Escherichia coli consists of 19 amino acid residues and is linked intramolecularly by three disulfide bonds between Cys6 and Cys11, Cys7 and Cys15, and Cys10 and Cys18 (Y. Shimonishi et al., FEBS Lett., 215, 165 (1987)). The syntheses and biological assays of various analogs of STh with one or two of the three disulfide bonds showed that a disulfide bond between Cys7 and Cys15 and another between Cys6 and Cys11 or Cys10 and Cys18 are necessary for construction and stabilization of the spatial structure of STh to express its toxicity.
Preparation of Poly(p-phenylene) by Electrooxidative Polymerization in Acidic Media
Authors: Yamamoto Kimihisa , Asada Toshio , Nishide Hiroyuki , Tsuchida Eishun 
Published: July 2006

Abstract
The electro-oxidative polymerization of benzene in the presence of strong acids yields poly(p-phenylene) efficiently. A strong protonic acid such as trifluoromethanesulfonic acid or Lewis acid such as an aluminum trichloride forms a complex with benzene and reduces the oxidation potential of benzene to 1.7 V, which brings about the high current efficiency. The acids act both as an electrolyte and as a catalyst in this polymerization of benzene.
Relative Standard Electrode Potentials of I3−/I−, I2/I3−, and I2/I− Redox Couples and the Related Formation Constants of I3− in Some Pure and Mixed Dipolar Aprotic Solvents
Authors: Datta Jayati , Bhattacharya Abhijit , Kundu Kiron Kumar 
Published: July 2006

Abstract
Standard potentials of I3−/I− and I2/I3− redox couples relative to that of aqueous saturated calomel reference electrode SCE (W), ESCE(w) have been determined in propylene carbonate (PC), N,N-dimethylformamide (DMF), acetonitrile (ACN), and their binary mixtures at 25 °C from potentiometric measurements. The results helped evaluate the standard potentials of the redox couple I2/I− relative to ESCE(w) as well as the related formation constant (Kf) of I3− in these solvent systems. The solvent effects on the formation equilibrium I2+I−\ightleftharpoonsI3− were analyzed in the light of the transfer free energies of I2, ΔGt°(I2), as obtained from solubility measurements of I2 in the solvents, that of I−, ΔGt°(I−), as obtained earlier by use of the widely used TATB reference electrolyte assumption and that of I3−, ΔGt°(I3−), as obtained by subtracting these two contributions from the respective transfer free energies of formation equilibrium in the mixed solvents relative to a chosen reference solvent in each solvent system. The solvation behavior of these individual iodine species viz. I2, I−, I3− was interpreted in terms of involved interaction viz. Born, ion-dipole, ion-induced dipole, dispersion type soft–soft interactions, CTTS complexation and also the cavity effect as computed by the scaled particle theory (SPT).
Theoretical Study of Some Non-Benzenoid Hydrocarbons: Benzo[3′,4′]cyclobuta[1′,2′:6,7]cycloocta[1,2,3,4-def]biphenylene and Related Compounds
Authors: Pal Sukanta K , Gupta Archana Das , Das Gupta Nanda K 
Published: July 2006

Abstract
Benzo[3′,4′]cyclobuta[1′,2′:6,7]cycloocta[1,2,3,4-def]biphenylene (1), benzo[6,7]cycloocta[1,2,3,4-def]biphenylene (2), dibenzo[a,c]benzo[3,4]cyclobuta[1,2-f]cyclooctene (3), and biphenyleno[8′,1′:4,5,6,7]cycloocta[1,2-l]phenanthrene (4) have been studied by semiempirical SCFMO method of Pariser and Parr and Pople. Core resonance intergral values of Lo and Whitehead, Dewar et al. and Yamaguchi et al. have been used. It has been observed that π*←π spectra predicted by the methods of Lo and Whitehead and Chung and Dewar suitable for the prediction of ground state properties are in good agreement with experimental results and comparable to those predicted by the method of Yamaguchi et al. developed for the prediction of spectral transitions. For comparison values obtained by configuration interaction method has also been included. Resonance stabilization of the molecules has been studied along with other properties such as bond length, ionization potential, electron affinity, and half-wave reduction potential.
Coordination Selectivity in Aluminum(III) Complex with 8-Hydroxy-7-[(2-hydroxy-5-carboxyphenyl)azo]-5-quinolinesulfonic Acid: Evidence for Linkage Isomerism
Authors: Bai Zhi-Ping , Einaga Hisahiko , Hidaka Jinsai 
Published: July 2006

Abstract
The coordination reaction of 8-hydroxy-7-[(2-hydroxy-5-carboxyphenyl)azo]-5-quinolinesulfonic acid (hcqs) to aluminum(III) has been investigated spectrophotometrically in a weakly acidic aqueous solution (pH 2–5) with 0.1 mol dm−3 NaCl at 22.0 °C; the thermodynamic stability, kinetics, and mechanism of the formation of the aluminum(III) complex were deduced. The ligand rapidly coordinates to aluminum(III), with its 8-quinolinol (O–N) moiety, to form a yellow complex (metal:ligand=1:1), and then the complex slowly changes, via an intramolecular rearrangement, to a red complex with its dihydroxyazo (O-N-O) moiety, thus showing a linkage isomerism. In the first coordination process, the complex is formed mainly via a pathway of the reaction of AlOH2+ with Hhcqs3−. The coordination reaction mechanism of aluminum(III) with related ligands, 4-hydroxy-3-[(2-hydroxy-5-carboxyphenyl)azo]-1-naphthalenesulfonic and 7-[(4-carboxyphenyl)azo]-8-hydroxy-5-quinolinesulfonic acid, is also discussed.
Preparation of New Nitrogen-Bridged Heterocydes. 18. Facile Formations of 3-Arylpyrazolo[1,5-a]pyridines and 1-Arylindolizines
Authors: Kakehi Akikazu , Ito Suketaka , Kinoshita Naosumi , Abaka Yukio 
Published: July 2006

Abstract
The alkaline treatment of 1-[(substituted benzylthio)methyleneamino]pyridinium and 1-[2-(substituted benzylthio)vinyl]pyridinium bromides possessing an electron-withdrawing substituent such as a nitro or cyano group in the presence or absence of a dehydrogenating agent afforded the corresponding 3-arylpyrazolo[1,5-a]pyridines and 1-arylindolizines in moderate to good yields, while the reactions of the parent pyridinium salts and those having an electron-releasing group did not produce any significant products. The mode of the reaction, a ring contraction-desulfurization, is the same as that observed in related monocyclic species.
Indirect Electrolytic Oxidation of Thioamides Using Organotellurium as a Mediator
Authors: Matsuki Toshiaki , Hu Nan Xing , Aso Yoshio , Otsubo Tetsuo , Ogura Fumio 
Published: July 2006

Abstract
Bis(p-methoxyphenyl) telluride (1) electrochemically reacted with supporting electrolytes such as tetrabutylammonium acetate and tetraethylammonium tosylate under anhydrous conditions to give tellurium(IV) diacetate 2a and ditosylate 2b, respectively. On the other hand, 1 was electrolyzed in the presence of water to give telluroxide 3. It has turned out that the tellurium compounds 2a and 2b like telluroxide 3 are mild oxidizing agents, but 2b behaves differently in a reaction towards thioamide. Thus 2a and 3 converted it into nitrile, while 2b did it into 1,2,4-thiadiazole. An indirect electrolytic oxidation of thioamides with 1 as a mediator was examined under various conditions. As a result, nitriles or 1,2,4-thiadiazoles could be chemoselectively formed, depending on the intermediacy of 2a or 3 as an active species for the former and 2b for the latter.
Synthesis of 2-(1-Phosphorylalkyl)- and 2-(1-Alkenyl)furans through Nitrile Oxide Cycloaddition Route
Authors: Tsuge Otohiko , Kanemasa Shuji , Suga Hiroyuki 
Published: July 2006

Abstract
A new synthetic method of 2-(1-phosphorylalkyl)furans with a variety of substituents on the ring is presented. Cycloaddition of (diethoxyphosphoryl)acetonitrile oxide to O-protected allyl alcohols is followed by a simple sequential procedure including Raney Ni reduction and acid treatment to give 2-(1-phosphorylmethyl)furans. The phosphorus-stabilized carbanions derived from the phosphorus-functionalized furans are applied to alkylation, oxidation with oxygen, or olefination to provide 2-(1-phosphorylalkyl)furans, 2-acylfurans, or 2-(1-alkenyl)furans, respectively. Some other synthetic applications are also described.
New and Convenient Synthesis of 2-Substituted 2,3-Dihydro-1H-benz[de]isoquinolin-1-ones
Authors: Sato Ryu , Oikawa Katsuyuki , Goto Takehiko , Saito Minoru 
Published: July 2006

Abstract
Various 2-substituted 2,3-dihydro-1H-benz[de]isoquinolin-1-ones were obtained in high yields by chemoselective reduction of 2-substituted 1H-benz[de]isoquinoline-1,3(2H)-diones with sodium or zinc borohydride at room temperature.