bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Crystal and Molecular Structure of N-(Thioacetyl)tryptamine. A Radioprotective Indole Compound
Authors: Ishida Toshimasa , Shimizu Satomi , Inoue Masatoshi , Kitamura Kunihiro , Tomita Ken-ichi , Shinoda Masato 
Published: July 2006

Abstract
The crystal structure of N-(thioacetyl)tryptamine, a radioprotective agent, has been determined by the X-ray method. The crystal is monoclinic, space, group P21/c with the unit cell dimensions: a=23.761(5), b=5.553(1), c=8.889(2) Å, and β=94.04(4)°. The structure was solved by the direct method and succesive Fourier syntheses, and refined by the block-diagonal least-squares method to give a final R-value of 0.072. In the crystal, the molecules are held together with van der Waals contacts between the nonpolar groups of adjacent molecules, and an inter-molecular hydrogen bond between the sulfur and nitrogen atoms of the side chain (N–H···S=3.322 Å). The folded conformation observed in this compound could be related to the protection of DNA against irradiation.
α,β-Unsaturated Carboxylic Acid Derivatives. XIX. The Convenient Synthesis of α-Alkoxy-, α-Hydroxy-α-amino Acid, and Its Cyclic Dipeptide from α-Dehydroamino Acid
Authors: Shin Chung-gi , Sato Yoshiaki , Ohmatsu Hisao , Yoshimura Juji 
Published: July 2006

Abstract
The facile conversion of α-dehydroamino acid into α-alkoxy-α-amino acid and its cyclic dipeptide is described. The reaction of t-butyl 2-acetylamino-2-alkenoate or 1-benzyl-3-ethylidene-2,5-piperazinedione with alcohol, water, or acetic acid in the presence of NBS or NGS, followed by reduction with 10% Pd–C, gives t-butyl 2-alkoxy-, 2-hydroxy-, and 2-acetoxy-2-(acetylamino)alkanoates, and 3-alkoxy-3-ethyl-2,5-piperazinedione respectively. All the new compounds were characterized by spectroscopic analysis.
Enzymatic Oxidation of Alkyl Sulfides by Cytochrome P-450 and Hydroxyl Radical
Authors: Watanabe Yoshihito , Numata Tatsuo , Iyanagi Takashi , Oae Shigeru 
Published: July 2006

Abstract
The oxidation of alkyl sulfides, sulfoxides, and sulfones was examined with either rabbit liver microsomes or a reconstituted system containing purified cytochrome P-450, S-dealkylation being found to take place more readily with alkyl sulfides bearing a higher acidic α-hydrogen. Similar results were obtained in the oxidation of alkyl sulfides by hydroxyl radical. Both S-dealkylation and S-oxygenation products are presumed to be formed via the cation radical intermediate.
Synthesis and Electrical Resistivity of TCNQ Radical Anion Salts with 4,5-Disubstituted N,N-Dimethyl-1,3-dithiolan-2-iminium Cations
Authors: Kato Futoshi , Tanaka Toshio 
Published: July 2006

Abstract
The title salts with the formula [S–CHR1–CHR2–S–C=\overset+NMe2](TCNQ)n\ewdot (R1,R2=Me, H; Et, H; Ph, H; Me, Me; and Me, Br; n=1 and 2) were prepared. Electrical resistivities, electronic spectra, and magnetic susceptibilities of these salts in the solid state are reported.
The Effect of Polar Solvent on the 1JCH Spin-Spin Coupling Constants in Halomethanes and Haloethylenes
Authors: Watanabe Shosuke , Ando Isao 
Published: July 2006

Abstract
The solvent effect on the 13C–1H nuclear spin-spin coupling constants (1JCH) of halomethanes and haloethylenes is calculated by means of the finite perturbation theory based on the CNDO/2 approximations incorporating the ‘solvaton’ theory. The results of the calculation explained the tendency of the observed solvent effect data in the literature.
Uptake of Zinc Ion by Hydrous Manganese (IV) Oxide
Authors: Narita Eiichi , Okabe Taijiro 
Published: July 2006

Abstract
The uptake of zinc ion by hydrous manganese(IV) oxide in ammonium chloride solution containing zinc ion was investigated. The uptake of zinc ion was found to be proportional to the potassium content in the hydrous manganese(IV) oxide, the molar ratio of the sorbed Zn2+ to the released K+ being ca. 1 : 2.
Synthesis and Reactions of Perylenecarboxylic Acid Derivatives. VII. Hydrolysis of N,N′-Dialkyl-3,4 : 9,10-Perylenebis(dicarboximide) with Sulfuric Acid
Authors: Nagao Yukinori , Misono Takahisa 
Published: July 2006

Abstract
The hydrolysis of N,N′-dialkyl-3,4 : 9,10-perylenebis(dicarboximide) (alkyl=CH3, CH2CH3, CH2CH2CH3, and CH2CH2CH2CH3) with sulfuric acid at 180–200 °C gave N-alkyl-3,4 : 9,10-perylenetetracarboxylic monoanhydride monoimide (alkyl=CH3, CH2CH3, CH2CH2CH3, and CH2CH2CH2CH3). The kinetics of the reaction were determined spectroscopically.
Some Properties of Fluorine-adsorbed Active Carbon
Authors: Watanabe Nobuatsu , Ueno Kazuo 
Published: July 2006

Abstract
Properties of fluorine-adsorbed active carbon (FAAC), expected to be a new fluorinating agent, were investigated by means of TG, X-ray diffraction, and ESCA. The fluorine in FAAC was desorbed by heat treatment in a vacuum at temperatures higher than 200 °C. The X-ray diffraction and ESCA measurements suggest that fluorine is inserted between the carbon layer planes of the active carbon, and combines with carbon atoms weakly in comparison with the C–F covalent bond. The reactivity of FAAC against several organic compounds was studied. 1-Butanol, 1-butanethiol, and cyclohexylamine were oxidized. Butyryl chloride was fluorinated to give butyryl fluoride.
Conditional Monte Carlo Trajectory Calculation of Elementary Gas Reaction Rates
Authors: Minami Ryuichi , Okada Takashi 
Published: July 2006

Abstract
A new Monte Carlo trajectory method is proposed to estimate the rate constants of elementary molecular reactions. In this study, we have introduced the conditional Monte Carlo technique and obtained the following advantages. First, the procedure of calculation has been simplified. That is, the trajectory data have been accumulated as only one data set, from which the rate constants at any temperature have been reduced easily. Secondly, the necessary number of trajectories has been decreased by employing appropriate conditional distribution functions. Lastly, the error estimation has become possible on a reasonable base. This method has been applied to the (H2, H2) direct exchange reaction as an example and the result is reported briefly.
Catalytic Activity of Highly Dispersed Palladium. I. The Mechanism of Cyclohexene Hydrogenation and the Role of ZrO2 Support
Authors: Lee Bu Yong , Inoue Yasunobu , Yasumori Iwao 
Published: July 2006

Abstract
The hydrogenation of cyclohexene vapor on dispersed palladium was studied in the pressure range of 10–40 Torr at temperatures between 283 and 323 K. Palladium was impregnated on ZrO2 and α-Al2O3 over the wide range of 0.03 to 2.1 wt%, and the percentage exposed was varied from 13 to 96% for Pd/ZrO2 and from 2 to 15% for Pd/α-Al2O3. The hydrogenation activity, Vg, per unit of weight of the Pd dispersed on ZrO2, exhibited a sharp maximum at 0.05 wt%, but the turn-over frequency, Vs, per exposed atom around this maximum remained almost constant, which shows the reaction to be structure-insensitive. The value of Vs for Pd/ZrO2 at 301 K was larger than those for Pd/α-Al2O3 and Pd bulk metal by one order of magnitude. The ZrO2 carrier affected the catalytic behavior of palladium; the reaction orders with respect to the hydrogen and cyclohexene pressures changed to 0.73±0.04 and 0.64±0.04 respectively from the corresponding values, 0.97±0.03 and 0.07±0.04 for Pd/α-Al2O3 and Pd metal. The deuterium distributions in the reactant and product molecules in the reaction with D2 suggested that the hydrogenation on Pd/ZrO2 and Pd/α-Al2O3 proceeds via the associative mechanism ; the slow step is assumed to be the reaction of the surface cyclohexyl radical with the adsorbed hydrogen atom. The poisoning due to preadsorbed CO decreased the catalytic activities of Pd/ZrO2 and Pd/α-Al2O3 almost linearly with the amounts of surface CO and caused a complete deactivation at about a half coverage of the surface Pd atoms, irrespective of the percentage exposed. On the basis of these results, the structure-insensitivity of the cyclohexene hydrogenation on Pd and the carrier effect of ZrO2 are discussed.
Intermolecular Potential, Vibrational Spectra, and Structures of Amino Acid Crystals. II. α-Glycine, l-Alanine, and Dl-Alanine Crystals
Authors: Machida Katsunosuke , Kagayama Akira , Kuroda Yoshihiro 
Published: July 2006

Abstract
The lattice energies, the deviations of the structure parameters from the model equilibrium, the molecular distortions due to the intermolecular interaction and the vibrational frequencies of α-glycine, l-alanine and Dl-alanine crystals were calculated from three sets of parameters for the pairwise atom-atom interaction potential functions. By comparing the calculated quantities with the observed ones, the combination of the exp-6 type non-bonded potential and the Lippincott type hydrogen bond stretching potential is shown to afford a better model of the intermolecular interaction in these crystals than the combination of the Lennard-Jones 6-12 potential and the general hydrogen bond 10-12 potential.
Adsorption of Neutral α-Amino Acids at the Mercury-Aqueous Solution Interface and Hydrophobicity Scales of Amino Acid Side Chains at the Electrified Interfaces
Authors: Kakiuchi Takashi , Senda Mitsugi 
Published: July 2006

Abstract
The adsorption of glycine, Dl-serine, l-threonine, l-asparagine, l-glutamine, l-valine, l-leucine, l-methionine, and l-tryptophan at the mercury-aqueous sodium fluoride solution interface has been studied by measuring differential capacities, potentials of zero charge, pzc, and surface tensions at the pzc. The standard adsorption free energies for these amino acids and for the amino acids previously studied have been used to deduce hydrophobicity scales of amino acid side chains at positively charged, negatively charged, and uncharged interfaces. The hydrophobicity scale at the uncharged interface was basically similar to that of Nozaki and Tanford. When the surface was charged positively, the positions of serine and alanine, and of threonine and α-aminobutyric acid, in the scale were reversed. This reversion was primarily ascribed to the difference in the positions of maximum adsorption potentials between the amino acids with an aliphatic side chain and those with a hydroxyl group in the side chain.
The Effect of Iron(III) on the Cadmium Ion-selective Electrode
Authors: Sakura Sachiko , Virtanen Rauno 
Published: July 2006

Abstract
Iron(III) interferes with the operation of a cadmium, lead and copper ion-selective electrode. The cadmium ion-selective electrode (CdS/Ag2S) showed a potential shift to the positive direction of more than 100 mV for a decade change of iron(III) concentration. However, the exact mechanism for this interference is not known, though it is expected to be the oxidation of sulfide ion by Fe(III). The mechanism of interference by iron(III) was studied by using the cadmium ion-selective electrode, flow-through cell, pH buffer solutions, potentiometric titrations, and atomic absorption spectrophotometry measurements. It was found that iron(III) promotes dissolution reaction of cadmium ions from the solid cadmium sulfide electrode and that flow conditions of samples have no effect on the iron(III) interference.
The Determination of Alkaline Phosphatase Activity in Serum by Means of Flow-through Analysis with an Ion-selective Electrode
Authors: Hara Tadashi , Imaki Masakatsu , Toriyama Motohiro 
Published: July 2006

Abstract
In order to determine continuously the alkaline phosphatase activity in a serum sample, a potentiometric method using a newly prepared phosphate ion-selective electrode has been established by the authors for the first time. The alkaline phosphatase activity was determined by measuring the concentration of the phosphate ion which was liberated by the enzymatic hydrolysis of disodium phenyl phosphate in the presence of alkaline phosphatase. The measurement of the phosphate ion with an ion-selective electrode was seriously interfered with by protein and the halide ion, but the interference could be removed by covering the electrode surface with a cellulose acetate membrane and by separating the chloride ion from a serum sample by gel chromatography. The present method was applied to the determination of alkaline phosphatase activity in serum; the results obtained showed a satisfactory correlation with those obtained by the conventional method. The method was found to be useful for practical diagnosis based on the activity of alkaline phosphatase.
The Methylation of Ribonucleosides by Trimethyl Phosphate or Dimethyl Sulfate in the Presence of Boric Acid
Authors: Hisanaga Yorisato , Tanabe Toshizumi , Yamauchi Kiyoshi , Kinoshita Masayoshi 
Published: July 2006

Abstract
Uridine, inosine, adenosine, and thymidine were methylated selectively at the base moieties by the use of trimethyl phosphate or dimethyl sulfate in the presence of boric acid. A suppressing effect of boric acid on the methylation of the ribose-hydroxyl groups was discussed briefly.
The Adsorption of Basic α-Amino Acids in an Aqueous Solution by Titanium(IV) Oxide
Authors: Okazaki Susumu , Aoki Teruaki , Tani Koichi 
Published: July 2006

Abstract
TiO2 showed a pronounced activity in the adsorption of basic α-amino acids, such as l-lysine and l-arginine, in an aqueous solution. The adsorptive activity of TiO2 containing sulfate ions was lower than that of the sulfate ion-free TiO2, and it was suppressed by phosphate ions. The pH of the aqueous solution hardly affected the adsorption, while the heat-treatment of TiO2 above 500 °C noticeably lowered the adsorption. The Langmuir equation was applicable to the adsorption of l-lysine, showing that the amount of saturated adsorption was about 0.7 mmol/g TiO2 heat-treated at 500 °C. The heat of adsorption of l-lysine, as determined from the adsorption isotherms at 10, 30, and 50 °C, was 2257 J/mol. A linear relationship was observed between the amount of l-lysine adsorbed and that of the surface OH groups.
The Crystal and Molecular Structure of the Photodimer of Biphenylene
Authors: Furusaki Akio , Hashiba Nobuhiro , Matsumoto Takeshi , Aotsuka Tomoji , Nishida Shinya 
Published: July 2006

Abstract
The molecular structure of the photodimer of biphenylene has been determined by X-ray crystal analysis. The crystals are triclinic, with eight molecules in a unit cell with dimensions of a=15.061, b=17.687, c=13.091 Å, α=108.91, β=98.52, and γ=89.71°; the space group is P\bar1. 6625 unique intensity data were collected on a four-circle diffractometer with LiF-monochromated Cu Kα radiation. The structure was solved by the symbolic-addition method using 8 symbols, and refined by the block-diagonal least-squares method. The final R value was 0.101. The molecular structure thus obtained corresponds to syn-13,14 : 15,16-dibenzotricyclo[6.4.2.22,7]hexadeca-1,3,5,7,9,11,13,15-octaene. Of the four crystallographically-independent molecules, two have approximately the C2v symmetry, while the remaining two are somewhat deformed, their symmetry being nearly C2. The molecules are held together mainly by van der Waals interactions.
Studies on Electrode Processes of Stabilized Zirconia Cell System by Complex Impedance Method
Authors: Sasaki Jun , Mizusaki Junichiro , Yamauchi Shigeru , Fueki Kazuo 
Published: July 2006

Abstract
Three kinds of materials, Pt, Ag, and La0.5Sr0.5CoO3, were applied to stabilized zirconia as electrodes and the electrode behavior was investigated by means of the complex impedance method. The impedance arc due to the electrode/stabilized zirconia interface was always depressed semi-circles. Impedance behavior was strongly dependent on the electrode materials. Assuming that the impedance arc could be interpreted by a parallel R-C circuit, the interface resistance Ri and the interface capacitance Ci were determined. The apparent activation energy determined from the slope of the plots of logRi vs. 1/T was nearly the same for the same electrode material. (Ag electrode: 92 kJ/mol and Pt electrode: 201 kJ/mol). The oxygen pressure dependence of Ci and Ri was also investigated. Although Ci was virtually independent of the oxygen partial pressure PO2, Ri was proportional to PO2−2⁄3 for Ag electrodes and PO2−1⁄4 for Pt electrodes. The rate-determining step was supposed to be the dissociation of oxygen molecules into atoms for Ag electrodes, and the dissociation of oxygen molecules or one of the subsequent steps for Pt electrodes.
Syntheses and Characterizations of μ-Dicarboxylato-bis[pentaamminecobalt(III)] Complexes
Authors: Ogino Hiroshi , Tsukahara Keiichi , Morioka Yoshiyuki , Tanaka Nobuyuki 
Published: July 2006

Abstract
Five new complexes, [(NH3)5Co(dicarboxylate)Co(NH3)5]X4 (dicarboxylate=oxalate, succinate, pimelate, fumarate, and maleate; X=ClO4− or Cl−), were synthesized by the reactions of [Co(hydrogen dicarboxylate)(NH3)5](ClO4)2 with [Co(NH3)5(H2O)](ClO4)3 and characterized by chromatographic behavior and electronic and NMR techniques. When maleate was used as the dicarboxylate, the formation of [(NH3)5Co(fumarate)Co(NH3)5]4+ as well as [(NH3)5Co(maleate)Co(NH3)5]4+ was observed. The IR and Raman spectra of [(NH3)5Co(oxalate)Co(NH3)5]4+ indicate that the symmetry of the oxalate ion in the complex may be approximated by D2h.
Multiple Paths for Photo-alkylation and -alkoxylation of 3-Pyridinecarboxylic Ester in Alcohol. Simultaneous Contribution of Several Kinds of Excited States
Authors: Sugimori Akira , Tobita Etsuo , Kumagai Yasuyuki , Satô Gen P 
Published: July 2006

Abstract
UV-irradiation of methyl 3-pyridinecarboxylate (1) in acidic alcoholic solutions brings about the alkoxylation and alkylation at the pyridine ring. Photoalkylation occurs in several paths: 1) alkylation initiated by the triplet π-π* state, 2) alkylation initiated by the triplet n-π* state of the carbonyl moiety of the ester group, 3) alkylation initiated by an exciplex between a free base form of 1 and a pyridinium form of 1, and 4) alkylation promoted by chloride ions. Photoalkoxylation originates from a singlet excited state of 1. In the photoreactions of 1 in strongly acidic methanolic solutions acidified with H2SO4, three kinds of excited states (two kinds of triplet states for alkylation and a singlet state for alkoxylation) contribute simultaneously.
Cyclization of Isothiosemicarbazones. IV. Synthesis of the [1,2,4]Triazolo[1,5-c]pyrimidine Ring System
Authors: Yamazaki Chiji 
Published: July 2006

Abstract
Condensation of isothiosemicarbazones with ethoxymethylenemalononitrile gave 2,3-dihydro[1,2,4] triazolo[1,5-c]pyrimidines in moderate to high yields. The 2,3-dihydro compounds were readily oxidized in dimethyl sulfoxide to give the corresponding [1,2,4]triazolo[1,5-c]pyrimidines.
Kinetic Studies of the Stripping of Bis(2,4-pentanedionato)beryllium in Various Liquid-Liquid Partition Systems
Authors: Watarai Hitoshi , Suzuki Nobuo 
Published: July 2006

Abstract
The rate constant, kst, for the stripping of bis(2,4-pentanedionato)beryllium from inert solvents into water or a mixed solvent of water with a miscible organic solvent, such as ethylene glycol, methanol, acetonitrile, and pimethyl sulfoxide, was determined and discussed in connection with the dissociation rate constant, kd, of the chelate in the aqueous phase and the liquid-liquid partition coefficient, P, of the chelate. The kst=kd⁄(1+P) relationship was found to hold true in all systems studied. The solvent effect of the aqueous mixed solvents on kd was discussed in terms of the transfer activity coefficient.
Synthesis of Oxazolidines, Thiazolidines, and 5,6,7,8-Tetrahydro-1H,3H-pyrrolo[1,2-c]oxazole (or thiazole)-1,3-diones from β-Hydroxy- or β-Mercapto-α-amino Acid Esters
Authors: Badr Mahmoud Zarif Amin , Aly Morsy Mohamed , Fahmy Atiat Mohamed , Mansour Mansour Esmael Younis 
Published: July 2006

Abstract
2-Aryl-4-(ethoxycarbonyl)oxazolidines and thiazolidines (1) were prepared from the corresponding α-amino acid ethyl esters containing either hydroxyl or mercapto groups in the β-position by fusion with some aromatic aldehydes. Dehydrogenation of 1 with N-bromosuccinimide gave the corresponding oxazoles and thiazoles. The oxazolidines and thiazolidines gave Mannich bases on interaction with p-nitrobenzaldehyde and piperidine. Acetylation of 1 gave the corresponding N-acetylderivatives, which on fusion in the presence of anhydrous ZnCl2 undergo cyclization, giving the corresponding bicyclic compounds, 5,6,7,8-tetrahydro-1H,3H-pyrrolo[1,2-c]oxazole (or thiazole)-1,3-diones.
Kinetics and Mechanism of Hydrolysis of Ruheman’s Purple in the Absence and Presence of Micelles in Aqueous Medium
Authors: Malaviya Sudhir , Katiyar Sarvagya S 
Published: July 2006

Abstract
The mechanism of acid hydrolysis of Ruheman’s purple has been investigated and the effect of micelles on the rate has been examined. First order rate constant for the hydrolysis reaction decreases linearly with decreasing hydrogen ion concentration up to pH 3 and levels off thereafter with no reaction occurring above pH 7. Increasing ionic strength decreases the rate in accordance with the Bronsted-Christiansen equation. The salt effect in the dipole-dipole reaction is probably a reflection of the fast equilibrium steps involving ions preceding the rate-determining step. Solvents like ethylene glycol and dioxane have no effect, indicating that the rate-determining step of the reaction does not involve ionic species. A mechanism of the reaction has been proposed which is consistent with our observed results. In the presence of micelles the reaction rate was strongly inhibited by the cationic micelles of hexadecyltrimethylammonium bromide, whereas anionic micelles of sodium dodecyl sulfate showed a slight enhancement. The micellar data have been analyzed on the basis of available models.
Reductive Elimination of d8-Organotransition Metal Complexes
Authors: Tatsumi Kazuyuki , Hoffmann Roald , Yamamoto Akio , Stille John K 
Published: July 2006

Abstract
A theoretical analysis of two aspects of the mechanism of reductive elimination is presented—how the choice of central metal and peripheral ligands affects the activation energy for reductive elimination from a four-coordinate MR2(PR3)2 complex and how ligand asymmetry controls cis-trans rearrangements and elimination pathways proceeding through three-coordinate intermediates. The following conclusions emerge: (1) In the four-coordinate complex, the better the σ-donating capability of the leaving groups, the more facile the elimination; (2) Stronger donor ligands trans to the leaving groups will increase the barrier to elimination; (3) The reductive elimination barrier in four-coordinate complexes is controlled by the energy of an antisymmetric b2 orbital, which in turn depends on the energy of the metal levels. The activation energy for such direct reductive elimination should be, and is, substantially lower for Ni than for Pt or Pd; (4) T-shaped trans PdLR2, arising from dissociation of L in PdL2R2, will encounter a substantial barrier to polytopal rearrangement to cis PdLR2, which in turn has an open channel for reductive elimination of R2; (5) If the leaving groups are poor donors, cis-trans isomerization in the three-coordinate manifold should be easier than elimination.
The Spectrophotometric Determination of Zirconium(IV) by Solvent Extraction with Trioctylphosphine Oxide and Benzophenone
Authors: Shigetomi Yasumasa , Kojima Takehiro 
Published: July 2006

Abstract
The colorimetric determination of zirconium(IV) was investigated by means of liquid-liquid extraction, where zirconium in a nitric-acid solution was quantitatively extracted into molten TOPO-benzophenone at about 60 °C. The organic phase solidifies on cooling and is separated and dissolved in methanol. The addition of an ethanolic solution of 1-(2-pyridylazo)-2-naphthol to this solution yields as intense red colour.