bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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<maltose<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

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

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

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

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

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

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

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

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

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

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>pyruvic acid≈4-methyl-2-oxopentanoic acid>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>phenylpyruvic acid ≈4-methyl-2-oxopentanoic acid>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

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.
The Effect of Organic Solvents on the Thermal Denaturation of Lysozyme as Measured by Differential Scanning Calorimetry
Authors: Fujita Yukihisa , Noda Yukinao
Published: July 2006

The thermal denaturation of lysozyme in aqueous solutions of N,N-dimethylformamide(DMF), N,N-dimethylacetamide(DMA), acetone, and dioxane at pH 3 was investigated by differential scanning calorimetry(DSC). The denaturation temperature, Td, decreased linearly with an increase in the concentration of organic solvent. The lowering in Td at identical concentrations of organic solvent increased in the order: acetone<DMF<DMA<dioxane. The calorimetric enthalpy of denaturation, ΔHd, showed a complex dependence on the solvent composition. For three organic solvents (not dioxane), the ΔHd first increased slightly with increasing the concentration of organic solvent and then started decreasing at different concentrations of each organic solvent. This behavior is analogous to those observed earlier with monohydric alcohols and with sulfoxides. For dioxane, on the other hand, the ΔHd decreased gradually with increasing the concentration of dioxane. The effect of these organic solvents on the thermal stability of lysozyme may correlate with their effect on the structure of water, which determines the strength of the hydrophobic interaction of the protein.
The Ullmann Condensation Reaction of Haloanthraquinone Derivatives with Amines in Aprotic Solvents. V. The Formation of Active Catalyst by the Partial Oxidation of Copper(I) with Molecular Oxygen
Authors: Arai Sadao , Hashimoto Yoshio , Takayama Nobuo , Yamagishi Takamichi , Hida Mitsuhiko
Published: July 2006

Although copper(I) is a more effective catalyst than copper(II) in the Ullmann condensation reaction of haloanthraquinones with ethylenediamine in aprotic solvents under a nitrogen atmosphere, the oxidation products of copper(I) by molecular oxygen enhanced the reaction rate compared to copper(I) catalyst. From the studies on the effect of Cu(II) salt addition to Cu(I) salt, solvent effects, and ESR spectra, it was concluded that alkoxycopper(II) species, formed by the oxidation of Cu(I) with molecular oxygen in alcohol–ethylenediamine solution, acted cooperatively with Cu(I) to increase the catalytic activity. The idea was also supported by the fact that the condensation was remarkably accelerated by the combination of Cu(I) and chloromethoxycopper(II). Reaction pathways including the alkoxo and halogen bridged Cu(I)···Cu(II) mixed valence complex are proposed and discussed.
The Molecular Structures of (t-Butyl)(chloro)[(−)-sparteine]magnesium(II) and Dichloro[(−)-sparteine]magnesium(II)
Authors: Kageyama Hiroyuki , Miki Kunio , Kai Yasushi , Kasai Nobutami , Okamoto Yoshio , Yuki Heimei
Published: July 2006

Crystals of t-BuMgCl–(−)-sparteine (1) belongs to orthorhombic system; P212121, a=25.689(6), b=10.030(2), c=7.942(2) Å, and Z=4; MgCl2–(−)-sparteine (2) also crystallizes in orthorhombic system; P212121, a=11.180(4), b=11.957(4), c=12.573(5) Å, and Z=4. Both structures were solved by the heavy atom method, and refined by the block-diagonal least-squares procedure; (1) R=0.098 for 1199 non-zero reflections and (2) R=0.091 for 1347 observed reflections. The Mg atom in each complex has a distorted tetrahedral geometry: (1) Mg–N=2.17(2) and 2.18(2), Mg–C=2.19(2), and Mg–Cl=2.332(7) Å and N–Mg–N=83.9(5)°; (2) Mg–N=2.150(9) and 2.160(9), and Mg–Cl=2.269(5) and 2.279(6) Å, and N–Mg–N=85.0(4)°.
Mass-spectrometric Measurements of Thermodynamic Properties of the Molten KCl–MnCl2 System
Authors: Sasamoto Tadashi , Itoh Mitsuru , Sata Toshiyuki
Published: July 2006

Activities and heats of mixing for the molten KCl–MnCl2 system were determined mass-spectrometrically by the ion-current ratio method. Activities of components KCl and MnCl2 show large negative deviations from Raoult’s law, indicating a very strong interaction between KCl and MnCl2. Entropies of mixing calculated from measured activities and heats of mixing have minimum values in the vicinity of 33% MnCl2, and have been compared with those calculated on the basis of some molten structure models to infer possible chemical species in the molten salt.
The Electrolytic Behavior of Tetrasubstituted Iminium Salt in Acetonitrile
Authors: Kunai Atsutaka , Harada Junji , Nishihara Masayasu , Yanagi Yasuo , Sasaki Kazuo
Published: July 2006

Cathodic behavior of N-cyclohexylidenepyrrolidinium salt (1) and N-cyclohexylideneaniline (2) in acetonitrile has been studied by means of dc polarography, cyclic voltammetry and preparative electrolysis under controlled potential conditions. The compound 1 exhibits a reduction wave at about −1.8 V, which is accompanied by formation of a surface compound. The products obtained from the preparative electrolysis were neither saturated amines nor dimeric compounds but were mostly polymeric materials. However, when electrophilic olefins, such as acrylonitrile or methyl acrylate, were present in the solution, coupling products were produced. The compound 2, which cannot be reduced by itself below −2.7 V, is reduced at about −1.8 V when benzoic acid is in the solution. The reduction product in this case was N-cyclohexylaniline, which was replaced by a coupling product when acrylonitrile was present in the reaction system. The formation of the coupling products is considered to occur by a radical mechanism in both cases.
Photochemical Dehalogenation of Polyhalobenzenes. I. Survey of the Reactivity in Hexane Solution
Authors: Nakada Masahiro , Fukushi Sachio , Nishiyama Hideaki , Okubo Keiji , Kume Kotaro , Hirota Minoru , Ishii Tetsuo
Published: July 2006

Photochemical dechlorinations and debrominations of C6HnX6−n (X=Cl, Br) isomers were carried out in hexane. The products and residual reactant were determined quantitatively by means of gas chromatography. From these experiments, the relative rates of dehalogenation were obtained. The different rates among unequivalent sites in a molecule were interpreted by the effect of steric acceleration by the neighboring halogen atom(s). The reactivity of the halogen atom in polyhalobenzene towards photochemical elimination reaction is dependent both on its position in the molecule when compared among isomers and on the number of halogen atoms in a molecule when compared among polyhalobenzenes of various degrees of substitution. The latter effect is more predominant in the series of polybromobenzenes.
A Facile One-pot Synthesis of Hydroxy-substituted Crown Ethers
Authors: Ikeda Isao , Katayama Tetsuya , Tsuchiya Kikuo , Okahara Mitsuo
Published: July 2006

Hydroxy-substituted crown ethers were prepared in one-pot synthesis by treatment of oligoethylene glycols with epichlorohydrin in the presence of alkali metals, alkali metal hydride or alkali metal hydroxides. The stability constants of complexes with sodium and potassium cations in methanol were determined.
Studies on the β-Turn of Peptides. IV. Effect of the Chain Length on the CD Spectra of N-(2,4-Dinitrophenyl)-(Gly)n–d-Ala–l-Pro–(Gly)n p-Nitroanilides (n=1–3)
Authors: Sato Kazuki , Taki Noriko , Nagai Ukon , Higashijima Tsutomu
Published: July 2006

N-(2,4-Dinitrophenyl)-(Gly)n–d-Ala–l-Pro–(Gly)n  p-nitroanilides (7b, n=2; 7c, n=3) were synthesized in order to study the effect of chain length on their conformations. The CD spectra of both 7b and 7c snowed similar patterns to that of 7a (n=1), but their Cotton effects were much weaker. Therefore, both compounds seem still to have some populations of folded conformers because their Cotton effects near 350 nm were significantly larger than those of the tetrapeptide derivatives in random conformation. However, the population of the folded conformers must be quite small.
Nucleophilic Substitution on 4-Methylbenzyl Thiocyanate with Nucleophiles
Authors: Oae Shigeru , Yamada Norihiro , Fujimori Ken , Kikuchi Osamu
Published: July 2006

The reactions of 4-methylbenzyl thiocyanate (1) with several nucleophiles have been investigated. Compound 1 possesses three electrophilic sites, i.e., benzylic carbon, sulfur and cyano carbon, to receive nucleophilic attack. PhS− and CN− which have HOMO’s of high energy levels appear to attack preferentially the sulfur atom. MeO− was found to attack preferably the cyanide carbon, while amines which have HOMO’s of low energy levels prefer benzylic carbon to attack. The nucleophilic substitution on the sulfur or the cyanide carbon generates CN− or p-xylene-α-thiolate anion, strong nucleophiles, as the primary products, which then initiate the complex secondary reactions. The selective reactivities of three attacking sites for nucleophiles in 1 have been rationalized in terms of MO theory.
Glass-like Carbon Made from Epoxy Resin Cured with 2,4,6-Trinitrophenol
Authors: Kawamura Kazuro , Kimura Shiushichi
Published: July 2006

It has been found that a glass-like carbon can be produced by the slow and carefully controlled pyrolysis of the epoxy resin (Epikote 828) cured with 2,4,6-trinitrophenol (TNP) with a weight of 10–15%. The most characteristic property of the glass-like carbon was seen in its change in density with the heat-treatment temperature. Under heat treatment at temperatures up to 1000 °C, a dense glass-like carbon of which density was 1.65–1.70 g/cm3 was formed. The density of the glass-liken carbon decreased, however, at heat-treatment temperatures above 1000 °C. Upon heat treatment at the temperature of 3000 °C, the density dropped to a low value of 1.04–1.11 g/cm3. The former increase in density is connected with the large-scale dehydration reaction which may proceed between nitro groups and hydrocarbon chains in the cure resin. The latter decrease in density is caused by the progress of the graphitic orientation of carbon-layer planes in the cross-linked structure of the highest degree. If carbon fibers were present in this glass-like carbon, the graphitization of the glass-like carbon in the composite proceeded more easily than that of the glass-like carbon alone.
Photodimerization Mechanism of m-Methoxystyrene via Its Cation Radical. Open Type Dimer Cation Radical as Its Intermediate
Authors: Yamamoto Masahide , Yoshikawa Hiroaki , Gotoh Tetsuya , Nishijima Yasunori
Published: July 2006

Two isomeric tetralin type dimers were obtained by UV excitation of m-methoxystyrene in the presence of an electron acceptor. Stepwise electrophilic dimerization mechanism through the dimer cation radical was confirmed. The scheme was analyzed with the aid of MO calculation.
The Lithium Diisopropylamide-induced Fragmentation of 1,3-Dithiolane Derivatives of Several Ketones Having α-Hydrogen
Authors: Ikehira Hideyuki , Tanimoto Shigeo , Oida Tatsuo
Published: July 2006

The reaction of 1,3-dithiolane derivatives of ketones having α-hydrogen with lithium diisopropylamide results in fragmentation to the corresponding thioketone followed by further conversion in a few steps to the other intermediate species which, on trapping with alkyl halide, leads to a vinylic sulfide and/or a sulfide bearing a secondary alkyl group.
Intramolecular Stereospecific Pummerer Reactions of Aryl (Substitutedmethyl) Sulfoxides Bearing Electron-withdrawing Groups with Acetic Anhydride
Authors: Numata Tatsuo , Itoh Osamu , Yoshimura Toshiaki , Oae Shigeru
Published: July 2006

The Pummerer reaction of optically active cyanomethyl aryl sulfoxides with acetic anhydride gave the corresponding α-acetoxy sulfides which were induced with a partial asymmetry nearly 30% at α-carbon, while the 18O-label of the original sulfoxides was retained in more than 85% in the resulting ester, the Pummerer reaction product. Kinetic experiments with cyanomethyl (p-substituted phenyl) sulfoxides and α,α-dideuterated cyanomethyl p-tolyl sulfoxide in the reaction with acetic anhydride containing a small amount of acetic acid revealed that the rates were correlated with Hammett σ-values and ρ-value of −0.70 was obtained, while the kinetic isotope effect was practically nil, i.e., kH⁄kD=1.01. These observations indicate clearly that the rearrangement is intramolecular and proceeds via forming a very intimate ion-pair and the rate-determining step is believed to be the S–O bond cleavage after the initial reversible acylation and deprotonation. Elimination of acetic acid proceeds through the Elcb type process. The uneven distribution of 18O in the two oxygens of the resulted ester, i.e., ether and carbonyl oxygens, suggests the recombination of the α-sulfenyl carbonium ion and acetate ion to be very rapid. The Pummerer reaction of optically active N,N-dimethyl-p-tolyl-sulfinylacetamide with excess acetic anhydride also gave the corresponding α-acetoxy sulfide in optically active form. In the presence of dicyclohexylcarbodiimide (DCC), the Pummerer reaction was found to be highly stereoselective affording the corresponding α-acetoxy sulfide with 65%e.e. Other optically active α-carbonyl-substituted alkyl sulfoxides, i.e., ethyl p-tolylsulfinylacetate and ω-(p-tolylsulfinyl)acetophenone also gave the corresponding highly optically active Pummerer rearrangement products in the treatment with acetic anhydride/DCC system. The Pummerer reaction of the 18O-labeled sulfoxides with acetic anhydride/DCC system gave the corresponding α-acetoxy sulfides which retained much of the original 18O-labels of the sulfoxides. These observations reveal clearly that in the Pummerer reaction of these compounds the acetoxyl migration is intramolecular and takes place through intimate ion-pairs.
The Long-wavelength nπ* Phosphorescence Spectra of p-Quinones in Polycrystalline Solutions at 77 K
Authors: Kuboyama Akira , Kojima Yoshikuni , Matsuzaki Sanae Y
Published: July 2006

Besides the usual nπ* phosphorescence spectra, broad, long-wavelength nπ* phosphorescence spectra are observed in normal paraffine solutions, such as a heptane solution, of 1,4-naphthoquinone, and in a benzene solution of 5,14 : 7,12-pentacenediquinone at 77 K. The energy difference between the two spectra are ca. 750 and 980 cm−1 respectively. The intensity of the long-wavelength spectra relative to the short-wavelength spectra becomes weaker with decreases in the concentrations of the quinones, and the lifetimes of the long-wavelength spectra are shorter than those of the short-wavelength spectra. These long-wavelength spectra are assigned to those of the quinone aggregates. The excitation spectra of these phosphorescences have also been obtained. An explanation of the above red-shift of the nπ* phosphorescence spectra of the aggregates is presented; in it, the phosphorescence state of the aggregates corresponds to the nπ* triplet excimer state.
Laser-induced Fluorescence of the NaCs Molecule
Authors: Onomichi Kyoko , Katô Hajime
Published: July 2006

Laser-induced fluorescence of NaCs is observed when a mixture of sodium and cesium is irradiated by the 5682 Å laser line. The spectroscopic constants of the ground state X1Σ+ have been determined and the potential energy curve was calculated by the RKR method. The excited state was identified as D  1Π, and the potential curve was estimated from the analysis of the fluorescence intensities.
Synergistic Solvent Extraction of Crown Ether Complexes with Alkali Metal Picrates by Neutral Donor Solvents
Authors: Takeda Yasuyuki
Published: July 2006

The solvent extraction of rubidium and caesium picrates has been studied at 25 °C with mixtures of crown ether and tributyl phosphate (TBP) or trioctylphosphine oxide (TOPO) in benzene, and the adduct-formation constants in the benzene solution have been calculated. The crown ethers used in this work were 12-crown-4 (12C4), 15-crown-5 (15C5), and benzo-15-crown-5 (B15C5). The stoichiometric composition of any extracted complex under the present experimental conditions is alkali metal ion : crown ether : TBP or TOPO : picrate ion=1 : 1 : 1 : 1. The TOPO complex is more extractable than the corresponding TBP complex. The extractability of the Rb+ complex is larger than that of the corresponding Cs+ complex. For both TBP and TOPO, the adduct-formation constant value sequences of Rb+ and Cs+ are B15C5>12C4>15C5 and 12C4>B15C5>15C5, respectively.
Studies on Lanthanoids–Antimony–Chalcogenides. I. Synthesis and Crystal Data of Three New Lanthanum Antimony Chalcogenides
Authors: Gao Jin-zhang , Nakai Izumi , Nagashima Kozo
Published: July 2006

Three new La–Sb chalcogenides were synthesized by hydrothermal or evacuated silica tube methods. (1) LaSbO2S2: a bright-red needle crystal; crystal system, hexagonal; space group, P63/m; lattice constants, a=14.954(3), c=3.898(2) Å, and Z=6. (2) La6Sb8S21: a blackish-red columnar crystal with metallic luster, orthorhombic, P222, a=14.317(2), b=15.239(4), c=8.685(1) Å, and Z=2. (3) La3Sb3S10: a bright-red platelike crystal, monoclinic, a=13.209(6), b=14.229(6), c=5.583(1) Å, β=94.54(3)°, and Z=2.
Intermolecular Stereoselective Pummerer Reactions of 4-(p-Chlorophenyl)thiane 1-Oxides and trans-1-Thiadecalin 1-Oxides and 2-Thiadecalin 2-Oxides with Acetic Anhydride
Authors: Oae Shigeru , Itoh Osamu , Numata Tatsuo , Yoshimura Toshiaki
Published: July 2006

The Pummerer reactions of conformationally fixed 4-(p-chlorophenyl)thiane 1-oxides and trans-1-thiadecalin 1-oxides and trans-2-thiadecalin 2-oxides with acetic anhydride are either stereoselective or stereospecific, both in the absence and in the presence of a scavenger of acetic acid formed, such as dicyclohexylcarbodiimide (DCC) or 2,6-lutidine. However, the 18O-tracer experiments with the 18O-labeled sulfoxide revealed the reaction to be an intermolecular rearrangement, while the kinetic experiment with α-deuterated 4-(p-chlorophenyl)thiane 1-oxides gave sizable values of kinetic isotope effect, i.e., 2.8 for the cis isomer and 3.4 for the trans isomer. In the reaction of 4-arylthiane 1-oxides with acetic anhydride, the thermodynamically controlled product is axial 2-acetoxy-4-(p-chlorophenyl)thiane while the kinetically controlled product is the equatorial isomer which is formed in the presence of the acid scavenger, DCC. In the Pummerer reaction of the thiadecalins S-oxides the equatorial α-acetoxy sulfides are the preferential products, however, the isomer preference is more pronounced in the reaction with DCC. These observations, along with other pertinent data seem to suggest that the rate-determining step in the Pummerer reaction of these simple heterocyclic sulfoxides is E2 elimination of acetic acid from the acetoxysulfonium intermediates.
The Catalytic Cracking of Slack Wax with Molten Mixtures Containing Aluminum Chloride and Bromide
Authors: Ohtsuka Yasuo , Oizumi Kazutoshi , Tamai Yasukatsu
Published: July 2006

The catalytic cracking of slack wax with molten mixtures of AlCl3 and AlBr3 was investigated in an atmospheric semi-batch reactor at low temperatures of 100–160 °C. The cracking rate was proportional to the amount of unreacted wax. The conversion at 135 °C reached 25 wt% under typical reaction conditions. About 95 wt% of the cracking products consisted of isobutane, 2-methylbutane, and methylpentanes, ca. 50% of these isoparaffins being isobutane. The difference in cracking activity between this catalyst and a solid acid catalyst is discussed based on the product distribution. Hardly any reaction took place without HCl, which shows that the presence of HCl is essential for this cracking. The cracking rate increased sharply with an increase in the amount of the catalyst. The rate did not depend on the composition of the AlCl3–AlBr3 catalyst, but the product distribution did depend on it and the content of the gasoline fraction in the products increased with an increase in the concentration of AlBr3. The cracking residue was characterized by IR and NMR spectroscopy. The results show that the cracking reaction probably occurs heterogeneously at the interface between the liquid wax and the molten catalyst.
Synthesis, Characterization, and Crystal-structure Analysis of the 2:1 Molecular Complexes between 1,3,5-Trinitrobenzene and Copper(II), Nickel(II), or Palladium(II) Complexes with the Schiff Base Ligands Derived from o-Hydroxynaphthaldehydes and Monoamines
Authors: Matsumoto Naohide , Hara Tadanori , Hirano Akira , Ohyoshi Akira
Published: July 2006

The molecular complexes between 1,3,5-trinitrobenzene(TNB) and copper(II), nickel(II), or palladium(II) complexes with the Schiff base ligands derived from 1-hydoxy-2-naphthaldehyde or 2-hydroxy-1-naphthaldehyde and monoamines (RNH2: R=CH3, C2H5, n-C3H7, i-C3H7, n-C4H9) have been prepared and characterized. One of the molecular complexes bis(1-(isopropyliminomethyl)-2-naphtholato)palladium(II)-bis(1,3,5-trinitrobenzene) (Pd(2,1-i-C3H7)2·2TNB) has been subjected to the single-crystal X-ray analysis. Its crystal structure consists of alternately stacked donor (naphthalene moiety of the metal complex) and acceptor (TNB) molecules. The coordination geometry is a square planar with a markedly stepped chair-like shape, where the seat and the rests are formed by the coordination plane (PdO2N2) and two naphthalene moieties. The Pd atom is deviated by 0.62 Å from the least-squares plane of the naphthalene ring and the dihedral angle between the coordination plane and the naphthalene ring is 25.1°. When the crystal structure was viewed perpendicular to the donor or acceptor plane, the center of the TNB molecule coincides approximately the center of terminal benzene ring of the naphthalene moiety. Electronic spectra of the molecular complexes in Nujol mull showed a new band at about 18×103 cm−1, which was not observed in solution spectra.
Studies in Nickel(IV) Chemistry. V. Kinetics of Electron Transfer in Redox Systems Containing Tris(dimethylglyoximato)nickelate(IV), Hydroxylamine, and Catalytic Amounts of Copper(II) in Aqueous Alkaline Media
Authors: Acharya Sridhara , Neogi Gautam , Panda Rama Krushna , Ramaswamy Dorai
Published: July 2006

Kinetics of electron transfer in the redox system containing hydroxylamine and tris(dimethylglyoximato)nickelate(IV) ([Ni(dmg)3]2−), in the presence of catalytic amounts of added copper(II) ions, have been studied in aqueous medium in the pH range 8.04–11.81. The kinetics exhibit pseudo-zero-order disappearance of [Ni(dmg)3]2− when excess [NH2OH]0 is present, in the presence and absence of added metal ions. While addition of Cu(II) results in significant catalysis, that of Co(II)/Co(III), Fe(II)/Fe(III), Ni(II) or Zn(II) does not. The pseudo-zero-order rate constants (k0) are found to be linearly dependent on [NH2OH]0 and on added [Cu(II)]. The k0 values register a decrease as [OH−] is increased in the pH range 8.04–ca.9.42, attaining a limiting value in the pH range ca. 9.8–ca. 11.81. Results are interpreted in terms of a probable mechanism involving formation of precursor complexes from hydroxylamine and Cu(II) species, followed by rate-determining breakdown of the precursors with concomitant electron transfer. The Cu(II)·aq species reacts several orders of magnitude faster than the Cu(OH)2·aq species. The Ni(IV) does not appear to have any kinetic role in the redox system and is involved only in rapid product formation steps. The stoichiometric ratios (Δ[Ni(IV)]/Δ[NH2OH]) of ca. 1.0 in the lower pH region (7.8–8.6) and ca. 0.5 in the higher pH region (9.1–11.6) are explained in terms of differential product formation.
The Chemical Preparation of Tin Organosol
Authors: Ichiba Sumio , Ono Hiroaki , Kawasaki Shunji , Nakagawa Sakae , Yamada Masaaki
Published: July 2006

A stable colloidal tin suspension in an organic solvent was prepared by the chemical reduction of tin(II) chloride with sodium tetrahydridoborate in the presence of a protective agent. The tin organosol was examined by means of the Mössbauer absorption spectra of 119Sn in the frozen solution and by means of an electron microscope.
The Crystal and Molecular Structure of Potassium u-fac-Bis(N-methyliminodiacetato)cobaltate(III) Sesquihydrate
Authors: Kushi Yoshihiko , Ideno Toshio , Yasui Takaji , Yoneda Hayami
Published: July 2006

The crystal and molecular structure of the title complex has been determined by X-ray analysis. It has been found that the cis-N2O4 octahedron about the cobalt(III) has a large distortion caused by the steric compression between the two adjacent N-methyl groups.
Metal-catalyzed Organic Photoreactions. The Photooxidation of Vinylsilanes and Vinyl Sulfides in the Presence of Iron(III) Chloride, and the Regioselective Synthesis of α-Chloro Ketones
Authors: Sato Tadashi , Tonegawa Tamotsu , Naoi Kunio , Murayama Eigoro
Published: July 2006

The irradiation of a pyridine solution of vinylsilanes or vinyl sulfides in the presence of iron(III) chloride under oxygen produced α-chloro ketones, with a carbonyl group at the olefinic carbon originally bearing a silicon or sulfur atom.
Bis(acetylacetonato)copper Catalyzed Cross-coupling Reaction of Alkenyldicyclohexylborane with 1-Bromo-1-alkyne or 3-Bromo-1-propene
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira
Published: July 2006

Bis(acetylacetonato)copper is capable of catalyzing cross-coupling reaction of alkenyldicyclohexylborane with 1-bromo-1-alkyne or 3-bromo-1-propene to give conjugated (E)-enyne or (E)-1,4-diene in a highly stereoselective manner, respectively.
Homoconjugation in Bicyclo[2.2.1]hept-2-en-7-yl and 1,4-Dihydro-1,4-methanonaphthalen-9-yl Radicals
Authors: Kawamura Takashi , Sugiyama Yoshio , Yonezawa Teijiro
Published: July 2006

2,3-Dimethylbicyclo[2.2.1]hept-2-en-7-yl and 6-methyl-1,4-dihydro-1,4-methanonaphthalen-9-yl radicals are examined wiht ESR. Comparisons of their hyperfine splitting constants with those of bicyclo[2.2.1]hept-2-en-7-yl (1a) and 1,4-dihydro-1,4-methanonaphthalen-9-yl (2a) radicals show that the odd electron on the tervalent carbon atom is delocalized to the extent of 10% into the π system of the vinylene bridge in 1a, and 5% at maximum into the π system of the phenylene bridge in 2a, respectively. This odd eletron delocalization is accompanied by an increase of carbanion character of the tervalent carbon atom. The nonplanarity of their tervalent carbon atoms is discussed in relation to the carbanion character.
The Crystal Structure of 11-(p-Bromophenyl)-11-cyano-12-phenyl-6b-(1-pyrrolidinyl)-6b,6c,11,12a-tetrahydroindeno[1′2′ : 3,4]-cyclopenta[1,2-a]acenaphthylene Acetone Solvate
Authors: Uechi Tetsuo , Tsuge Otohiko , Okita Shigeru , Kanemasa Shuji
Published: July 2006

The title compound crystallizes in the triclinic space group P\bar1 with two fomrula units in a unit cell of dimensions; a=11.621(3), b=15.177(3), c=10.229(2) Å, α=95.63(2), β=105.46(2), and γ=76.43(2)°. The crystal structure was solved by a conventional heavy-atom method and refined by block-diagonal least-squares procedures to give a final R value of 0.050 for 3428 reflections, with Fo>2σ(Fo), collected on a four-circle diffractometer. The bond distance shared between the acenaphthene and the cyclopentane rings is unusually long at 1.596(6) Å, which may result from the additional strain induced by the fusion of these rings. The solvent molecules are disordered in the channel composed of the main molecules.
Synthesis of Mesoionic Triazolopyridine. III. Applications of N-Acyl Mesoionic Triazolopyridines as Acylating Reagents
Authors: Saito Akio , Shimizu Bunji
Published: July 2006

Utility of N-acyl mesoionic triazolopyridines as acylating reagents was investigated concerning with peptide synthesis. Several dipeptides and N-alkoxycarbonyl amino acids were prepared by use of these reagents.
An Improved Resolution of β-Hydroxy-Dl-aspartic Acid on Optically Active Resin Containing l-Lysine or l-Ornithine
Authors: Anpeiji Shigeharu , Toritani Yasunobu , Kawada Kazunori , Kondo Seiji , Murai Shinji , Okai Hideo , Yoshida Hisanobu , Imai Hideo
Published: July 2006

A series of experiments on column chromatography of the optically active resin containing l-lysine or l-or nithine were carried out with pyridinium acetate and ammonium acetate solvent systems as the eluents. threo-β-liydroxy-Dl-aspartic acid was found to be resolved on the optically active resin containing l-lysine with ammonium acetate solvent system; erythro-β-hydroxy-Dl-aspartic acid could be resolved on that containing l-ornithine with pyridinium acetate solvent system. The threo or erythro racemate was resolved on a preparative scale, and the resolution including the complete characterization of enantiomers resolved was first accomplished.
Production of C2(d3IIg) by Controlled Electron Impact on Acetylene, Ethylene, and Ethane
Authors: Ogawa Teiichiro , Ueda Yasuhiro , Higo Morihide
Published: July 2006

The emission spectra produced by controlled electron impact on C2H2, C2H4, and C2H6 have been analyzed to gain insight into the production mechanisms of C2(d3Πg) from the three molecules. There are four thresholds on the excitation function of C2(d3Πg) from C2H2. Its vibrational temperatures are 22000 K for C2H2, 30000 K for C2H4 and 56000 K for C2H6 at an electron energy of 100 eV. Doubly-excited states are involved in the dissociative excitation of C2H2.
The Crystal and Molecular Structure of Albocycline
Authors: Furusaki Akio , Matsumoto Takeshi , Harada Ken-ichi , Suzuki Makoto , Kinoshita Kenji , Hayashi Mitsuo , Nakatsu Kazumi
Published: July 2006

The detailed molecular geometry of albocycline (C18H28O4) has been examined by X-ray crystal analysis. The crystals are monoclinic, with four molecules in a unit cell with dimensions of a=16.177(2), b=9.562(1), c=11.742(2) Å, and β=90.43(1)°; the space group is P21. 3062 unique intensity data were collected on a four-circle diffractometer with graphite-monochromated Mo Kα radiation. The structure was elucidated by the Monte Carlo direct method, using the 30 reflections with the greatest |E| values as the starting set; the 174th random phase set led to the correct solution. The R value reached 0.057 by block-diagonal least-squares refinements. The two crystallographically-independent molecules are connected by two O–H···O hydrogen bonds, forming a hydrogen-bonded dimer. The conformations of the fourteen-membered macrolide rings in these two molecules are considerably different from each other; e.g., great differences of 165, 153, and 108° are found for the torsion angles around the C(4)–C(5), C(6)–C(7), and C(7)–C(8) single bonds respectively.