bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reaction of Sulfur Dichloride with Nitrile in the Presence of Lewis Acid Forming 1,2,4-Thiadiazole
Authors: Komatsu Mitsuo , Shibata Jun-ichi , Ohshiro Yoshiki , Agawa Toshio 
Published: July 2006

Abstract
Formation of 3,5-disubstituted 1,2,4-thiadiazoles by the reaction of sulfur dichloride with nitriles in the presence of a Lewis acid was found. For example, 3,5-diphenyl-1,2,4-thiadiazole was obtained with its chlorinated products, 3-o-chlorophenyl-5-phenyl- and 3-p-chlorophenyl-5-phenyl-1,2,4-thiadiazoles, from benzonitrile and sulfur dichloride using aluminium chloride as a catalyst (total yield 80%). The extent of chlorination of the aromatic ring was suppressed by use of iron(III) chloride as the catalyst or of sulfur chloride instead of the dichloride. Some substituted benzonitriles and pivalonitrile also gave thiadiazoles in lower yields.
Stereospecific and Stereoselective Reactions. IX. Preparation of Ethyl (2E, 7R)-7-Acetoxy-4-oxo-2-octenoate from d-Glucose
Authors: Yokota Sumio , Nishida Mitsuru , Mitsunobu Oyo 
Published: July 2006

Abstract
Reaction of methyl 2,3-anhydro-4,6-dideoxy-α-d-ribo-hexopyranoside with MgI2 exclusively afforded methyl 3,4,6-trideoxy-3-iodo-α-d-xylo-hexopyranoside which was dehalogenated by treatment with LiAlH4 to give methyl 3,4,6-trideoxy-α-d-erythro-hexopyranoside (2). Hydrolysis of 2 and subsequent treatment with ethoxycarbonylmethylenetriphenylphosphorane gave ethyl (2E, 4R, 7R)-4,7-dihydroxy-2-octenoate (10). Oxidation of 10 by-active MnO2 resulted in the formation of an equilibrium mixture of ethyl (2E, 7R)-7-hydroxy-4-oxo-2-octenoate (the carbon skeleton of pyrenophorin) and cyclic hemiacetal. On treatment with acetic anhydride, the mixture afforde dethyl (2E, 7R)-7-acetoxy-4-oxo-2-octenoate.
Syntheses of 1-Epikanamycin A and Its 1-N-[(S)-4-Amino-2-hydroxybutyryl] Derivative
Authors: Takahashi Yoshiaki , Tsuchiya Tsutomu , Suzuki Yukiko , Umezawa Sumio , Umezawa Hamao , Fukatsu Shunzo 
Published: July 2006

Abstract
The titled compounds were prepared from 3,6′-bis(N-benzyloxycarbonyl)-3″-N-(trifluoroacetyl)kanamycin A (1). Oxidation of 1 with hydrogen peroxide in the presence of sodium tungstate gave the 1-hydroxyimino derivative, which, after deblocking, gave 1-deamino-1-dehydro-1-hydroxyiminokanamycin A (6). Reduction of 6 with Raney nickel–hydrogen in aqueous ammonia gave a mixture of kanamycin A and 1-epikanamycin A (9), which were separated through derivation to the corresponding tetrakis-N-(t-butoxycarbonyl) derivatives, which showed different solubility in chloroform. 1-N-[(S)-4-Amino-2-hydroxybutyryl]-1-epikanamycin A was prepared from 9 by the zinc acetate–ethyl trifluoroacetate method [to give 3,6′-bis(N-benzyloxycarbonyl)-1-epi-3″-trifluoroacetamidokanamycin A] followed by a regiospecific 1-N-acylation with (S)-4-benzyloxycarbonylamino-2-hydroxybutyryl group and successive deblocking.
Induced Circular Dichroism of Two Chromophores Included in γ-Cyclodextrin
Authors: Kobayashi Nagao , Hino Yoshihiro , Ueno Akihiko , Osa Tetsuo 
Published: July 2006

Abstract
Induced circular dichroism (ICD) has suggested that γ-cyclodextrin (γ-CDx) accommodates two molecules of naphthalene and its derivatives with nearly axial inclusion but that it includes two Acridine Orange (AO) molecules with S-helicity.
The Stereoselective Dehydrative α-Glucosylation Using 6-O-Acetyl- and 6-O-p-Nitrobenzoyl-2,3,4-tri-O-benzyl-d-glucopyranoses
Authors: Koto Shinkiti , Morishima Naohiko , Kihara Yasuhiro , Suzuki Hideko , Kosugi Shigeharu , Zen Shonosuke 
Published: July 2006

Abstract
The stereoselective synthesis of α-linked glucobiose derivatives using 6-O-acetyl- or 6-O-p-nitrobenzoyl-2,3,4-tri-O-benzyl-d-glucopyranose and a ternary mixture of p-nitrobenzenesulfonyl chloride, silver trifluorometh-anesulfonate, and triethylamine in dichloromethane is described.
Effects of Cation on Transport Efficiency and Selectivity of Amino Acid Derivative Anions through Macrocyclic Carrier-containing Liquid Membrane
Authors: Tsukube Hiroshi 
Published: July 2006

Abstract
New aspects of amino acid transport mediated by macrocyclic carriers were reported. Its transport “efficiency” and “selectivity” were demonstrated to be controlled by the appropriate choice of co-transported cation and employed carrier-type.
The Structure of Aryldialkyltriazene N-Oxides
Authors: Giumanini Angelo G , Lassiani Lucia , Nisi Carlo , Petric Andrej , Stanovnik Branko 
Published: July 2006

Abstract
The structure of 3-aryl-1,3-dimethyltriazene 1-oxides has been demonstrated by comparison with other triazenes and triazene N-oxides by mass spectrometry and 1H and 13C NMR.
Arrhenius Parameters for the Reactions of Hydrogen and Deuterium Atoms with Four Butenes
Authors: Kyogoku Takeshi , Watanabe Toshifumi , Tsunashima Shigeru , Sato Shin 
Published: July 2006

Abstract
The absolute rate constants of the H and D atom addition to 1-butene, cis- and trans-2-butenes, and isobutene have been measured over the temperature range 200–500 K at the total pressure of about 600 Torr (1 Torr=133.3 Pa). The rate constants obtained were well expressed by the Arrhenius equations: k(H+1-butene)=(2.48±0.43)exp[−(1492±94)⁄RT], k(H+cis-2-butene)=(2.67±0.39)exp[−(1918±83)⁄RT], k(H+trans-2-butene)=(3.96±0.27)exp[−(2096±37)⁄RT], k(H+isobutene)=(2.08±0.16)exp[−(860±49)⁄RT], k(D+1-butene)=(2.42±0.72)exp[−(1642±169)⁄RT], k(D+cis-2-butene)=(2.25±0.19)exp[−(2082±48)⁄RT], k(D+trans-2-butene)=(2.33±0.23)exp[−(2036±55)⁄RT], and k(D+isobutene)=(1.54±0.19)exp[−(879±81)⁄RT] in units of 10−11 cm3 molecule−1 s−1. The isotope effects due to the difference between H and D atoms can simply be explained by the difference in collision frequency. The difference between cis- and trans-2-butenes in reactivity may be explained in terms of the pre-exponential factors.
Direct Measurement of the Interaction Energy between Solids and Gases. IX. Heats of Adsorption of Ammonia and Pyridine on Several Solids at High Temperature
Authors: Tsutsumi Kazuo , Mitani Yoshio , Takahashi Hiroshi 
Published: July 2006

Abstract
Heats of adsorption of ammonia and pyridine on H–Y zeolites and other solids were measured using a microcalorimeter in the temperature range of 313 to 673 K. Infrared spectra of adsorbed ammonia and pyridine were obtained in order to interpret the calorimetric data. There appeared two kinds of the temperature dependence of heats of adsorption. One is that heats of adsorption on H–Y5.0 and silica-alumina do change with coverage to a greater extent at high temperature range (above 473 K) than low temperature range. The difference in the shape of the heat curves was found to be attributable to the difference in the selectivity of adsorption at different temperatures, that is, adsorption occurred on stronger acidic sites is preference to weaker or non-acidic sites in the high temperature range, while random adsorption occurred simultaneously on acidic and non-acidic sites in the low temperature range. The other kind of temperature dependence was recognized to appear as a slight decrease in heats of adsorption with a temperature rise, which were observed in cases of ammonia adsorption on H–Y zeolites above 473 K and on Na–Y and silica above 313 K while the shapes of heat curves were similar to one another irrespective of the adsorption temperature. Such decrease may be attributed to the fact that the temperature dependence of the heat of adsorption was thermodynamically defined by the difference in molar heat capacity between adsorbed state and gaseous state.
Direct Measurement of the Interaction Energy between Solids and Gases. XI. Calorimetric Measurements of Acidities of Aluminum Deficient H–Y Zeolites
Authors: Mitani Yoshio , Tsutsumi Kazuo , Takahashi Hiroshi 
Published: July 2006

Abstract
Heats of adsorption of pyridine and ammonia were respectively measured on aluminum deficient H–Y zeolites using a microcalorimeter at 473 K. The calorimetrically determined acidity was discussed in relation to the positional difference between 3640 and 3550 cm−1-OH acidic sites and compared with the catalytic activity. Dealumination generally brings about a decrease in the acid site concentration. However, the extent of the decrease varied with the kind of titrated base and a significant change was observed in the ratio of acid site concentration when titrated with pyridine. This may be explained by the fact that the pore size of the zeolite becomes widely distributed as dealumination proceeds; 3550 cm−1-OH sites in supercages must become accessible to such a large molecule as pyridine. Also observed with dealumination was a slight increase in the heat of adsorption from initial to the middle stage of adsorption, which reflected the enhancement in acid strength of each OH site. The catalytic activity for cumene cracking increased with dealumination, which agreed with the acidity determined by the adsorption of pyridine rather than ammonia.
Kinetic Instability of Nonbenzenoid Aromatic Hydrocarbons
Authors: Aihara Jun-ichi 
Published: July 2006

Abstract
Aromatic hydrocarbons have thermodynamically stable cyclic conjugated systems. There is a tacitly accepted view that not only aromatic stabilization but also kinetic stability arise from the same cyclic conjugation of π electrons. In order for this view to be examined criticaly, two reactivity indices, i.e., localization energy and superdelocalizability, were adopted for a variety of cyclic conjugated hydrocarbons, and were compared with those defined for their olefinic reference structures. Interestingly, it was found that chemical reactivity of some constituent carbons might often overcome aromatic stabilization of an entire conjugated system. Not a few nonbenzenoid aromatic hydrocarbons were predicted to have reactive carbons which are olefinic in reactivity. These hydrocarbons constitute unstable aromatic compounds. Thus, it has been clarified that thermodynamic and kinetic stabilities do not always concur in the case of nonbenzenoid hydrocarbons.
Excitation Energy Dependence of Intramolecular Exciplex Formation and Electronic Relaxation in the Collision-free Vapor
Authors: Itoh Michiya , Hanashima Yukio , Wada Naoko , Hanazaki Ichiro 
Published: July 2006

Abstract
The excitation energy dependence of the intramolecular exciplex formation and the electronic relaxation has been studied in the collision-free vapor of 1-(9,10-dicyano-2-anthryl)-3-(pentamethylphenyl)propane. The fluorescence quantum yields and lifetimes of the 9,10-dicyanoanthryl moiety and the intramolecular exciplex in the collision-free vapor were observed to depend on the excitation energy within the S1 absorption band. From the quantum yields and the decay rate constants, the excitation energy dependence of the association and dissociation rate constants of the intramolecular exciplex formation were determined. The association rate constant of the exciplex formation increases more remarkably with increasing excitation energy than the nonradiative rate constants of 9,10-dicyanoanthryl moiety and the exciplex. The excitation energy dependence of the association rate constant was discussed in terms of the nonradiative transition from the initial optical state to the final exciplex and the level density of the final state, which were calculated in the simple model system by means of the semi-classical mechanics.
Thermodynamic Study on Penetration of Pentadecanoic Acid Monolayer by Dodecylammonium Chloride
Authors: Hayami Yoshiteru , Aratono Makoto , Uryu Shozo , Motomura Kinsi , Matuura Ryohei 
Published: July 2006

Abstract
In order to show that our thermodynamic treatment [J. Colloid Interface Sci., 87, 333 (1982)] is useful in the study on the monolayer penetration, the surface tension has been measured with the system consisting of pentadecanoic acid monolayer and dodecylammonium chloride solution. Applying the thermodynamic equations to the experimental data, the surface density of dodecylammonium chloride, and entropy and energy of penetration have been estimated numerically. It has been found that the surface density, entropy, and energy all decrease with increasing the concentration of film-forming substance. Therefore, it has been concluded that the penetration of monolayer of this system is caused by the decrease of the energy of penetration which compensates the decrease of the entropy of penetration.
Studies on Aqueous Solutions of Saccharides. II. Viscosity B-Coefficients, Apparent Molar Volumes, and Activity Coefficients of d-Glucose, Maltose, and Maltotriose in Aqueous Solutions
Authors: Miyajima Koichiro , Sawada Masahiro , Nakagaki Masayuki 
Published: July 2006

Abstract
Viscosities, apparent molar volumes, and activity coefficients of aqueous solutions for d-glucose, maltose, and maltotriose were measured at various concentrations. The signs of Bst, the increment of viscosity B-coefficient arising from structural change of water, were positive for these three saccharides, and the signs of dB⁄dT, the temperature dependence of B, were negative. The magnetudes of Bst and |dB⁄dT| increased with the number of glucose residue. Activity coefficients were larger than unity and increased with concentration, and their magnitudes also increased with the number of glucose residue. These results indicate that d-glucose, maltose, and maltotriose are structure forming solutes, and that their abilities lie in the order of d-glucose&lt;maltose&lt;maltotriose.
Polarographic Studies of the Ion-pair Formation and Conjugation Reactions of Acetate and Benzoate Ions in Acetonitrile
Authors: Hojo Masashi , Imai Yoshihiko 
Published: July 2006

Abstract
An acetate ion (A−) formed a homoconjugated species, A− (HA)2, with 2 molecules of acetic acid (HA) in the presence of a large excess of HA in an acetonitrile solution. In the presence of both acetic acid and LiClO4, one molecule of HA was derived from A− (HA)2 by means of a lithium ion to from an ion-paired species, HA2−Li, as follows: A−(HA)2+Li+\oversetKex\ightleftharpoonsHA2−Li++HA. The equilibrium constant, Kex, was evaluated as 1.1×104 from the shift in the anodic half-wave potential of the acetate ion. As for the benzoate ion (A′−) and HA′, similar reactions occured, and the constant of the exchange reaction was evaluated as 6×103. The effect of the sodium ion and HA (or HA′) on the A− (or A′−) ion was complicated. On the other hand, the presence of [M(A′)2]− (M=Li, Na, K) was proved by the shift of the cathodic wave of the alkali metal.The addition of water caused the apparent stability constant of [Li(A′)2]− to decrease extremely.
Kinetic Studies of Fast Equilibrium by Means of High-performance Liquid Chromatography. IV. Separation of Rotamers of Palladium(II) Dithiocarbamates
Authors: Moriyasu Masataka , Hashimoto Yohei , Endo Masaru 
Published: July 2006

Abstract
The restricted rotation about carbon-nitrogen bonds of unsymmetrical palladium(II) dithiocarbamate chelates has been investigated by high-performance liquid chromatography. At higher temperatures, the rotation is so rapid that two rotamers have not been distinguished, and a single sharp peak has appeared on chromatograms, whereas at lower temperatures, they have been separated. The activation energy of the rotation of palladium(II) dithiocarbamate (ΔH\eweq=83±5 kJ mol−1 for Pd(C6H5CH2CH2NHCSS)2) is smaller than usual values of the energy barrier to rotate double bonds, but larger than those to rotate single bonds.
Use of Normal Pulse Voltammetry in Diagnosing Electrode Kinetics of Octacyanomolybdate(IV/V) Complexes Bound Electrostatically to Graphite Electrodes Coated with Polyelectrolytes
Authors: Sato Keiichi , Yamaguchi Shuichiro , Matsuda Hiroaki , Ohsaka Takeo , Oyama Noboru 
Published: July 2006

Abstract
An electron transfer process of [Mo(CN)8]4−⁄3− redox couple at the graphite electrode/protonated poly(4-vinylpyridine) (PVP) interfaces was examined by the normal pulse voltammetry. It became apparent that electrode reaction of the electroactive species confined in the polymer film on electrode surface obeys the conventional Butler-Volmer equation which characterizes the ordinary electrode reaction at electrode/solution interface. From the analysis of the dependences of the current-potential curves upon the sampling time the relevant kinetic parameters (i.e., the standard rate constant, k° and the transfer coefficient, α) of the electrode reaction were evaluated. The value of k° decreased from 9.7×10−4 to 1.7×10−4 cm s−1 and the value of α was almost constant (0.50), when the molar ratio of the incorporated [Mo(CN)8]4− to pyridine group of the PVP film, ΓM⁄ΓPVP, was increased from 0.0025 to 0.22. The apparent diffusion coefficient, Dapp, for the process of charge transport within the film was also determined from the dependence of the limiting current upon the sampling time. The value of Dapp decreased from 4.4×10−8 to 2.5×10−9 cm2 s−1, when the ratio ΓM/ΓPVP was increased from 0.0025 to 0.22.
Baeyer-Villiger Oxidation with Me3SiOOSiMe3 under Assistance of SnCl4 or BF3·OEt2
Authors: Matsubara Seijiro , Takai Kazuhiko , Nozaki Hitosi 
Published: July 2006

Abstract
Treatment of ketones with bis(trimethylsilyl) peroxide and Lewis acid such as SnCl4 or BF3·OEt2 in dichloromcthane at room temperature affords esters in fair to excellent yields. Jasmine lactone is synthesized from 2-[(Z)-2-pentenyl]cyclopentanone by means of Me3SiOOSiMe3–BF3·OEt2 system without any protection of the carbon-carbon double bond. The oxidation of enol acetates of ketones to α-hydroxy (or α-acetoxy) ketones with Me3SiOOSiMe3–FeCl3 system is also disclosed.
Complex Formation between Molybdate and Alizarin Red S
Authors: Kato Takanori , Murayama Teisuke 
Published: July 2006

Abstract
The complex formation between molybdate and Alizarin Red S (ARS) has been studied by spectrophotometry and pH titration. Results by the former method confirm that the composition of the complexes formed corresponds to a ratio of 1:1 for molybdate to ARS and that the complexes are stable between pH 2 to 6. Those by the latter are summarized by the following stability constants at 25 °C and an ionic strength of 0.1: MoO42−+ars3−+2H+=MoO3ars3−+ H2O, log(β1⁄mol−3L3)=20.18±0.01; MoO42−+ars3−+3H+=MoO3(Hars)2−+H2O, log(β2⁄mol−4L4)=24.93±0.04 (the completely deprotonated species of ARS is denoted by ars3−, and the concentration of H2O is not included in the definition of stability constants). Protonation constants of MoO42− and ars3− were also determined under the same conditions.
Synthesis of 4H-Cyclopenta[def]phenanthrene from Fluorene Skeleton
Authors: Yoshida Masaaki , Minabe Masahiro , Suzuki Kazuo 
Published: July 2006

Abstract
4-Fluoreneacetic acid was prepared and its chloride was cyclized with AlCl3 to give 4H-cyclopenta-[def]phenanthren-8-ol accompanied by the 8,9-dione. These were both reduced to 4H-cyclopenta[def]phenanthrene: the overall yield was 40–50% from diphenic acid. The phenol was converted to acetoxy and amino substrates.
Conversion of Lupeol into Dammarane Derivatives
Authors: Ohta Shinya , Tori Motoo , Tsuyuki Takahiko , Takahashi Takeyoshi 
Published: July 2006

Abstract
On treatment with potassium carbonate in aqueous dioxane, 3β-tetrahydropyranyloxybaccharan-18β-yl mesylate, prepared from lupeol, underwent D-ring contraction. The solvolytic products were hydrolyzed and acetylated to give Δ20-, Δ20(22)-, Δ17(20)-, and Δ13(17)-dammaren-3β-yl acetates and (20S)-20-hydroxydammaran-3β-yl acetate together with bacchar-13(18)- and -12-en-3β-yl acetates.
Catalysis by “Copper Chromite”. I. The Effect of Hydrogen Reduction on the Composition, Structure, and Catalytic Activity for Methanol Decomposition
Authors: Iimura Akira , Inoue Yasunobu , Yasumori Iwao 
Published: July 2006

Abstract
The effect of hydrogen reduction on the composition, structure, and catalytic activity of dichromium(III) copper(II) tetraoxide (copper chromite), CuCr2O4, was investigated. In this oxide, the surface and the bulk CuII was reduced into CuI and further to Cu0 by heating in hydrogen. The methanol decomposition on fresh copper chromite proceeded in a manner similar to that on metallic copper formed as the result of strong reduction and dispersed on chromium(III) oxide. The contribution of CuII, CuI, and Cu0 species to catalytic activity was examined and the similarity in the character of reaction on these two samples with different surface states was discussed. The role of Cr2O3 interacting with zerovalent copper was postulated.
Simultaneous Determination of Trace Amounts of Carbazole and Anthracene in Dibenzofuran by Synchronous Fluorescence Spectrometry after Zone-melting Separation
Authors: Tachibana Masaki , Furusawa Motohisa 
Published: July 2006

Abstract
Trace amounts of carbazole and anthracene in dibenzofuran can be simultaneously determined by measuring the synchronous fluorescence intensities at 336 and 381 nm respectively. The determination limit is 2 ppm. For the application of this method to the practical samples containing interfering impurities, a zone-melting technique was applied successfully to remove the impurities prior to the determination. The recoveries of carbazole and anthracene were 99 and 92% respectively.
A Kinetic Study of a Zn2+-catalyzed Transamination Reaction between Pyridoxamine Analogs with a Pyridinophane Structure and α-Keto Acids
Authors: Tachibana Yoji , Ando Makoto , Kuzuhara Hiroyoshi 
Published: July 2006

Abstract
The kinetics of the nonenzymatic transamination reaction from pyridoxamine analogs with a pyridinophane structure to α-keto acids catalyzed by Zn2+ were investigated by monitoring the changes in the absorption spectra in methanol. It was found that these reactions obeyed first-order kinetics for the formation of the Zn2+ chelate of an aldimine. No appreciable change in the reaction rate was observed when the concentration of the α-keto acid was increased, indicating that the isomerization of the ketimine chelate to the aldimine chelate is the ratedetermining step. There was a considerable enhancement of the reaction rate when the molar ratio of the zinc ion to the pyridoxamine analogs was reduced from 1/1 to 0.5/1. The reaction rates corresponding to the various α-keto acids employed in the presence of an amount of Zn2+ equimolar to the pyridoxamine analog decreased in this order; phenylpyruvic acid&gt;pyruvic acid≈4-methyl-2-oxopentanoic acid&gt;3-methyl-2-oxobutanoic acid, whereas those in the presence of half-molar equivalents of Zn2+ to the pyridoxamine analog decreased in this order; pyruvic acid&gt;phenylpyruvic acid ≈4-methyl-2-oxopentanoic acid&gt;3-methyl-2-oxobutanoic acid. Furthermore, the use of the pyridoxamine analog with a linear “ansa” bridge resulted in a larger reaction rate than the use of the one with a branched “ansa” bridge. The solvent isotope effect is also described.
Oxidation of Lipids. IV. Formation and Reaction of Chromanoxyl Radicals as Studied by Electron Spin Resonance
Authors: Tsuchiya Jyunichi , Niki Etsuo , Kamiya Yoshio 
Published: July 2006

Abstract
In order to study the inhibition of oxidation by vitamin E, the formation and reaction of chromanoxyl radicals and hindered phenoxyl radicals were examined by ESR. t-Butoxyl radical abstracted the phenolic hydrogens of α-, β-, γ-, and δ-tocopherols, 2,4,6-tri-t-butylphenol (TBP), and 2,6-di-t-butyl-4-methylphenol (BMP) to give corresponding phenoxyl radicals which were stable enough to be observed by ESR. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) also induced the formation of chromanoxyl and phenoxyl radicals. The ESR spectra of chromanoxyl radicals were recorded and their hyperfine coupling constants were determined. The phenoxyl radicals from TBP and BMP disappeared quite rapidly when excess t-butyl hydroperoxide was added, whereas α-chromanoxyl radical from α-tocopherol remained considerably. α-Chromanoxyl radical and phenoxyl radicals reacted with p-t-butylbenzenethiol to regenerate α-tocopherol and corresponding phenols respectively. The implications of these results are discussed.