bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Transition Metal-catalyzed N-Heterocyclization. A Reductive Transformation of Aminonitroarenes and Dinitroarenes into Phenanthroline Derivatives Using Aliphatic Aldehydes under Carbon Monoxide Pressure
Authors: Watanabe Yoshihisa , Suzuki Naoki , Tsuji Yasushi 
Published: July 2006

Abstract
The Catalytic N-heterocyclization of aminoarenes and dinitroarenes using aliphatic n-C3–C5 aldehydes was carried out at 180 °C under the pressure of carbon monoxide (70 atm at room temperature) in the presence of RhCl(PPh3)3 and PdCl2 as a binary catalyst system. The reaction of p-nitroaniline with propanal, butanal, and pentanal gave 3,8-diethyl-2,9-dimethyl-4,7-phenanthroline, 2,9-diethyl-3,8-dipropyl-4,7-phenanthroline, and 3,8-dibutyl-2,9-dipropyl-4,7-phenantroline in 43, 57, and 54% yields respectively. On the other hand, m-nitroaniline and o-nitroaniline gave 1,7-phenanthroline and imidazole derivatives in rather low yields (21 and 24%) under the reaction conditions employed.
Studies on Heteropentalenes. V. Cycloadditions of 5-Aryl-3-methylimidazo[5,1-b]thiazoles with Acetylenic Esters Leading to 5-Aryl-3-methylthiazolo[2,3-c]benzimidazoles and Related Heterocycles
Authors: Abe Noritaka , Nishiwaki Tarozaemon , Ikeda Kotaro 
Published: July 2006

Abstract
Cycloaddition of 5-aryl-3-methylimidazo[5,1-b]thiazoles with dialkyl acetylenedicarboxylate in an aprotic nonpolar solvent gives a number of products including epimeric thiazolo[2,3-c]benzimidazoles (3 and 4) [1:2-cycloadducts], epimeric 5,10b-ethenothiazolo[3′,2′:3,4]imidazo[1,5-a]-pyridines (5 and 6) [1:3-cycloadducts], and thiazolo[3′,2′:3,4]imidazo[1,2-a]pyridines [1:3-adducts]. At higher temperature, formation of the 1:2-cycloadducts is favored over the 1:3-adducts, whereas the latter predominates at room temperature. In an aprotic polar medium, the 1:3-cycloadducts (5 and 6) and tetraalkyl 6-arylpyridine-2,3,4,5-tetracarboxylates are substantially produced. Epimerization of 3 and 4 has been found to compete well with fragmentation to 4H-1,4-benzothiazine.
Ring Opening of Oxiranes by Trimethylsilyl Trifluoromethanesulfonate
Authors: Murata Sizuaki , Suzuki Masaaki , Noyori Ryoji 
Published: July 2006

Abstract
Trimethylsilyl trifluoromethanesulfonate promotes ring opening reactions of oxirane derivatives. The reaction course is highly affected by the structures and substitution pattern of the substrates. Tetra-, tri-, and 2,2-disubstituted oxiranes and simple cycloalkene oxides are converted to the corresponding allylic alcohol trimethylsilyl ethers. The overall transformation is interpreted in terms of trans addition of the silyl trifluoromethanesulfonate to the oxirane ring followed by base-promoted anti elimination of a trifluoromethanesulfonic acid element. 2,3-Dialkyl- or monoalkyloxiranes isomerize to the corresponding ketones and aldehydes, respectively. (Z)-Cyclooctene oxide undergoes the transannular reaction to give endo-cis-2-trimethylsiloxybicyclo[3.3.0]octane. The reaction of 6-methyl-5-hepten-2-one oxide produces 2,2,6-trimethyl-3-trimethylsiloxy-3,4-dihydro-2H-pyran. 1,2-Methyl migration takes place in the reaction of (E)-3α-t-butyldimethylsiloxy-5α-pregnene 17α,20-oxide to afford 3α-t-butyldimethylsiloxy-17β-methyl-17α-[1-(trimethylsiloxy)ethyl]-18-nor-5α-androst-13(14)-ene. α-Pinene oxide gives trans-carveol trimethylsilyl ether.
The Reaction of Isocyanides with Halogens or N-Halosuccinimides and Alcohols
Authors: Yamada Hideyo , Wada Yasuo , Tanimoto Shigeo , Okano Masaya 
Published: July 2006

Abstract
The reaction of aliphatic isocyanides with bromine or chlorine in primary alcohols, followed by hydrolysis, afforded the corresponding carbamates in moderate yields, together with various amounts of amines. Bromine was superior to chlorine as a halogen source for the formation of carbamates. unexpectedly, the addition of HgCl2 resulted in a decrease in the carbamate yield. When N-halosuccinimides were used in the place of halogens, an additional formation of the succinimide-incorporated product was observed to some extent.
The Electric-field Analyses of a System with an Axial Symmetry and Its Application to the Infrared Intensity
Authors: Kanesaka Isao , Hiroya Yoshihiro , Kawai Kiyoyasu 
Published: July 2006

Abstract
The method of solving the Laplace equation for a system with axial symmetry is formulated in terms of the finite element method. The molecule having C3V point symmetry is assumed to have axial symmetry, and the van der Waals radii of the component atoms are used to estimate the shape of the central molecule. The method is applied to the IR intensity of the C≡N stretching mode of acetonitrile in various states. The observed intensities are adequately explained by the use of the local and reaction fields, except for the intensity in a solution diluted infinitely in chloroform. The intensity in chloroform can, however, reasonably be explained by taking the hydrogen bond into consideration.
The Interaction of a Neutral Polymer with Small Ions in Solution. I. A Method for the Analysis of Ion Binding to a Neutral Polymer
Authors: Awano Hiroshi , Ono Katsumichi , Murakami Kenkichi 
Published: July 2006

Abstract
A method for the analysis of ion binding to a neutral polymer, such as poly(oxyethylene) (POE), based on the one-dimensional lattice model has been proposed. The grand partition function for the one-dimensional lattice has been given by the product of the statistical weight matrix. Interaction between the ions bound to the lattice points has been well approximated by the Debye-Hückel pair-by-pair potential, and the distance between the bound ions has been assumed to be the root mean square end-to-end distance of the partial chain. Based on the model, an equilibrium constant has been defined which is referred to the binding constant.
Theoretical Considerations of the Dimer-formation Energy and Electronic Structures of the Monomer and Dimer of the 2-Pyridone by the Molecular Orbital Method
Authors: Inuzuka Kozo , Fujimoto Akira 
Published: July 2006

Abstract
When the dimer-formation energy of 2-pyridone was measured by means of 1H-NMR spectroscopy, the value of 65.3 kJ mol−1 was obtained. It is much larger than the hydrogen-bond energies which are generally observed for the C=O···H–N system. The dimer-formation energy of 2-pyridone was calculated by means of the CNDO/2 method; its formation energy (−ΔH) was estimated to be 68.2 kJ mol−1. The electronic structures of the monomer and dimer of 2-pyridone were calculated by means of the CNDO method with configuration interaction (CNDO/CI) in order to clarify the previous band assignment of the UV spectrum of 2-pyridone. According to the calculated results, the absorption bands at 305 and 228 nm in isooctane (2,2,4-trimethylpentane) were assigned to the monomer, while those at 297.5 and 230.5 nm were assigned to the dimer.
The Molecular Structure of Trimethylphosphine–Boron Triiodide as Studied by Gas-phase Electron Diffraction
Authors: Iijima Kinya , Koshimizu Eiichi , Shibata Shuzo 
Published: July 2006

Abstract
The molecular structure of trimethylphosphine-boron triiodide (CH3)3P·BI3 has been determined by means of gas-electron diffraction. The molecular parameters and their uncertainties were rg(B–I)=2.233±0.003 Å, rg(P–B)=1.947±0.011 Å, rg(C–P)=1.809±0.003 Å, rg(C–H)=1.094±0.008 Å, ∠IBI=111.6±0.3°, and ∠CPC=106.0±0.5°. The gaseous molecule was rigid with respect to the rotational vibration around the P–B bond.
The Stereochemistry and Reactivity of Metal–Schiff Base Complexes. V. The Solvent Effect on the Stereoselectivity of Cobalt(III) Complexes Containing a sal2en-type Schiff Base and l-Amino Acid
Authors: Fujii Yuki , Kuwana Yasuo , Takahashi Sozo , Shimizu Keiko , Hiroi Kumiko 
Published: July 2006

Abstract
The solvent effect on the stereoselectivity between Λ- and Δ-β2-diastereoisomers of cobalt(III) complexes with the general formula of [Co(Schiff base)(l-aa)], where Schiff base represents sal2en2−, α-Me-sal2en2−, and 5,6-benzo-sal2en2−, and where l-aa denotes l-alaninate, l-valinate, l-methioninate, and l-phenylalaninate, was studied. Generally, the Λ-β2-isomer was more stable than the Δ-β2-isomer in solution, and the stereoselectivity of all the l-ala-complexes and of the l-met-complex with 5,6-benzo-sal2en increased in the following order of solvents : acetone=DMF≤t-BuOH&lt;s-BuOH&lt;i-PrOH&lt;n-BuOH&lt;n-PrOH&lt;EtOH&lt;MeOH. On the other hand, the stereoselectivity of l-val- and l-phe-complexes with sal2en and 5,6-benzo-sal2en increased in the following order : acetone=DMF&lt;MeOH&lt;EtOH&lt;n-PrOH&lt;n-BuOH&lt;i-PrOH&lt;s-BuOH&lt;t-BuOH. In the case of 5,6-benzo-sal2en complexes with l-val and l-ile, the Δ-β2-isomer was preferred rather than the Λ-β2-isomer in acetone and DMF with 8–13% stereoselectivity. From the spectroscopic evidence, a hydrogen bonding between the OH group of alcoholic solvents and phenolic oxygen atoms of a Schiff base ligand was assummed, and the above phenomena were explained in terms of the steric difference between the Λ- and Δ-β2-isomers for the solvation with the alcoholic solvents by means of the hydrogen bonding.
Synthesis, Ion Exchange Properties, and Analytical Applications of a Novel Tin(IV)-edta Ion Exchanger
Authors: Ashfaq Nabi Syed , Rao Rifaqat Ali Khan 
Published: July 2006

Abstract
Tin(IV)-edta compound has been synthesized by mixing aqueous solutions of tin(IV) chloride and disodium salt of ethylenediaminetetraacetic acid (EDTA=H4 edta) in different conditions. The most stable sample is prepared by mixing 0.1 mol dm−3 solution of tin(IV) chloride with 0.1 mol dm−3 solution of disodium salt of edta in the volume ratio of 3:2 at pH 2.5 and refluxing the mixture for 16 h. Ion exchange capacities of the material for alkali metals are significantly smaller (0.26–0.20 mequiv./g) than for alkaline earths (0.74–0.40 mequiv./g). The thermal and chemical stability of this material has been compared with amine-tin hexacyanoferrate(II). Analytical importance of this material has been established by achieving a number of quantitative separations on its columns.
Gas-chromatographic Measurements of Dinitrogen Oxide in Surface Air
Authors: Hirota Michio , Muramatsu Hisafumi 
Published: July 2006

Abstract
The mixing ratio of N2O in surface air was measured at Tsukuba between July and September, 1980. The mean was 0.325 ppm, and the standard deviation was 0.008 ppm. No difference in the N2O content was found between the air blowing from the northeast or south and calm air.
The Preparation and Catalytic Properties of the Silica-supported Rhodium Complex
Authors: Okano Tamon , Kobayashi Teruyuki , Konishi Hisatoshi , Kiji Jitsuo 
Published: July 2006

Abstract
The RhH2(O2COH)[P(i-Pr)3]2 complex is attached to the phosphinated silica prepared from a new linking agent, Ph2PCH2CH2CH2Si(OCH3)3. The supported complex is an active catalyst for the hydrogenation of methyl cinnamate with CO and H2O, and it can be used repeatedly with little loss of activity, whereas the polystyrene-supported one is not recoverable because of the insufficient complexation of the rhodium.
Ozonization of Organic Compounds. VI. Relative Reactivity of Protic Solvents toward Carbonyl Oxide
Authors: Yamamoto Yorihiro , Niki Etsuo , Kamiya Yoshio 
Published: July 2006

Abstract
Tetramethylethylene was ozonized at 0 °C in several binary protic solvents and the relative reactivities of the solvents toward acetone carbonyl oxide were measured. The reactivity was found to decrease in the order methanol, ethanol, propyl alcohol, isopropyl alcohol, water, t-butyl alcohol, and acetic acid.
An Experimental Approach to the Prebiotic Synthesis of α-Amino Acids under UV Irradiation in Aqueous Medium
Authors: Nishizawa Masato , Egami Fujio 
Published: July 2006

Abstract
N-Oxaloglycine obtained from a glyoxylic acid and ammonia mixture was allowed to produce various α-amino acids under UV irradiation using an alkylating agent such as an olefin in the presence of acetone as the initiator. Aspartic acid, norvaline, valine, leucine, phenylalanine, and tyrosine were identified by TLC, amino acid analysis, GC, and GCMS techniques.
Trimethylsilyl Triflate Induced Reaction of Humulene 6,7-Epoxide. Cyclization to 5-Hydroxy-4,8,11,11-tetramethyltricyclo[6.3.0.02,4]undec-9-ene
Authors: Shirahama Haruhisa , Murata Shizuaki , Fujita Terunori , Chhabra Baldev R , Noyori Ryoji , Matsumoto Takeshi 
Published: July 2006

Abstract
Humulene 6,7-epoxide was converted by treatment with trimethylsilyl triflate to 5-hydroxy-4,8,11,11-tetramethyl[6.3.0.02,4]undec-9-ene in 81% yield.
Synthesis, Luminescence Quantum Yields, and Lifetimes of Trischelated Ruthenium(II) Mixed-ligand Complexes Including 3,3′-Dimethyl-2,2′-bipyridyl
Authors: Nakamaru Katsumi 
Published: July 2006

Abstract
New five complexes of the type of [RuL3−x(dmby)x]X2(x=1,2,3, L=2,2′-bipyridyl or 1,10-phenanthroline, dmby=3,3′-dimethyl-2,2′-bipyridyl, X=halide ion) have been synthesized in order to investigate the effects of two methyl groups of dmby on the absorption and emission spectra, luminescence quantum yields, and lifetimes. Values of the radiative and nonradiative rate constants have been calculated from these data at 77 K. Although the absorption and emission maxima and the lifetimes are not much affected by the dmby ligand substitution, the molar extinction coefficients and emission quantum yields are decreased compared with trischelated complexes of the parent bipyridyl or phenanthroline ligands. At 25 °C the emission yields of the complexes containing dmby decrease by 3–4 orders of magnitude than at 77 K. Possible causes of the decrease in the quantum yields are discussed.
The Oxidation of Carbon Monoxide on Pt/Al2O3 Containing a Metal Oxide
Authors: Kosaki Yukio , Miyamoto Akira , Murakami Yuichi 
Published: July 2006

Abstract
By using a three-way catalyst containing a metal oxide, CO is removed as CO2 even in the “rich” region of the air/fuel ratio. In order to elucidate the mechanism of this action of the added metal oxide, the reaction of CO with O2 on a Pt–V2O5/Al2O3 catalyst was investigated using a rectangular pulse-reaction apparatus. In the CO–O2 reaction on a Pt/Al2O3 catalyst, a significant amount of unreacted CO was exhausted in the “rich” region of the reactants. Furthermore, the conversion of CO decreased markedly with an increase in the CO/O2 ratio in the reactants. In the CO–O2 reaction on the Pt–V2O5/Al2O3 catalyst, on the other hand, the conversion of CO was high and did not decrease markedly with an increase in the CO/O2 ratio in the “rich” region. As for the reaction on the Pt–V2O5/Al2O3 at 558 K and above, the CO was completely removed as CO2 at any of the CO/O2 ratios examined. These effects of the added V2O5 were found to be due to: (i) the reaction of CO with an oxygen of V2O5 in the Pt–2O5/Al2O3 catalyst and (ii) the enhanced oxidation of CO with a gaseous O2 on the Pt/Al2O3 catalyst upon the addition of V2O5. On the basis of the kinetics of the oxidation of CO with the oxygen of V2O5 in the Pt–V2O5/Al2O3 and Pt black–V2O5 mixtures, its mechanism was proposed to be as follows; the oxygen of V2O5 at the Pt–V2O5 interface is activated by contact with Pt (this activated oxygen is denoted by [Pt···O···V]). The oxidation of CO with the oxygen of the Pt–V2O5/Al2O3 and Pt black–V2O5 mixtures proceeds according to the following two steps. Step I is the reaction of a gaseous CO with the active oxygen at the Pt–V2O5 interface, [Pt···O···V], to form CO2 and a reduced site, [Pt V]. Step II is the oxidation of the reduced site with the bulk oxygen in V2O5 to reproduce [Pt···O···V]. The enhanced oxidation of CO with a gaseous O2 caused by the addition of V2O5 to Pt/Al2O3 was found also to be understandable in terms of the active site, [Pt···O···V], where the reduced site, [Pt V], is oxidized by the gaseous O2 to reproduce [Pt···O···V] instead of the bulk oxygen in V2O5.
Electronic Structures of Pyridinols and of Their Anions and Cations
Authors: Morita Hiroshi , Kwiatkowski Józef S , Tempczyk Anna 
Published: July 2006

Abstract
Electronic structures of the lactim and lactam forms of 2-, 3-, and 4-pyridinols, and of their anions and protonated cations were calculated by a modified CNDO-CI (mCNDO-CI), CNDO/S-CI, and a modified π-SCF-MO-CI methods. The theoretical results agree well with the observed spectra of both the neutral and ionic species, and predict satisfactorily the shorter wavelength shift of lower excited π-π* and n-π* bands of the lactim form compared to the corresponding bands of the lactam form. The π-π* assignment to the lowest triplet states of 2- and 4-pyridones, and of 2- and 3-pyridinols, together with the n-π* assignment to the lowest singlet state of 4-pyridone was predicted by the mCNDO-CI method, in agreement with the suggestion based on emission properties. The orbital energies calculated by the mCNDO method were compared with the observed photo-electron spectra; the results show that the fourth highest occupied orbital is π-orbital in 2- and 3-pyridinols, and σ-orbital in 4-pyridinol and 4-pyridone.
Elementary Patterns in Protein-Nucleic Acid Interactions. IV. Crystal Structure of 3-(Adenin-9-yl)propionamide : 1-Methylthymine (1 : 1) Complex Dihydrate
Authors: Takimoto Midori , Takenaka Akio , Sasada Yoshio 
Published: July 2006

Abstract
As a ternary interaction model between adenine:thymine base pair and carbamoyl group, 3-(adenin-9-yl)-propionamide: 1-methylthymine complex was prepared and its crystal structure was examined. The crystal exhibits a disordered structure, and the structure unit is a monoclinic cell with dimensions a=11.368(1), b=6.909(1), c=12.708(2) Å, and β=114.49(1)°. The space group is P21 and the unit cell contains two complexes and four water molecules. The base pairing pattern between adenine and thymine is the Hoogsteen type. The carbamoyl group is hydrogen-bonded to N(A1) of adenine in this base pair, the distance NH···N(A1) being 2.94(2) Å. With two kinds of hydrogen bonds of the carbamoyl group, NH···N(A1) above-mentioned and NH···O(carbamoyl), the 3-(adenin-9-yl)propionamide molecules form a sheet extending perpendicular to the c axis; the base-paired thymine molecules extrude alternately from the sheet. Diffused spots along c* with half integers of l can be interpreted as a stacking disorder of the sheets.
Temperature Effect on the Adsorption of Ionic Surfactants at Water/Hexane Interface from Micellar Solutions
Authors: Yamanaka Michio , Aratono Makoto , Iyota Hidemi , Motomura Kinsi , Matuura Ryohei 
Published: July 2006

Abstract
The adsorption behavior of dodecylammonium chloride (DAC) and sodium dodecyl sulfate (SDS) at their aqueous micellar solution/hexane interface has been studied by measuring the interfacial tension as a function of temperature at concentrations around the critical micelle concentration (cmc). The derivative of the interfacial tension with respect to temperature has been observed to change abruptly at the cmc and very little thereafter with increasing concentration in a limited range above the cmc. By applying the thermodynamic treatment of adsorption from micellar solution developed previously to the present experimental results, the entropy changes associated with the adsorption of DAC and SDS from monomeric state and from micellar state and the corresponding energy changes have been calculated. Further, the entropy and energy changes of micelle formation have been obtained from these quantity changes. These values have been compared with those obtained for DAC at water/air interface. It has been observed that the behavior of the micelle in the limited concentration range is controlled solely by temperature and pressure and bears resemblance to that of the adsorbed film at the interface. It has also been observed that the entropy and energy of micelle and adsorbed film are lowered by the hexane existing in the system.
Photon Echo of Pentacene Molecules Introduced in Crystals with High Concentration
Authors: Yoshikuni Yuzo , Nakamura Arao , Shionoya Shigeo 
Published: July 2006

Abstract
Photon echo decay time is measured for pentacence molecules introduced in naphthalene and p-terphenyl crystals with rather high concentrations (10−6–105 mol/mol) at temperatures between 1.6 K and 4.1 K, using a tunable picosecond laser system consisting of a mode-locked YAG laser and a parametric oscillator. In naphthalene echo decay time increases with lowering temperature approaching a constant value below 2 K, but in p-terphenyl it is almost constant. The phase relaxation time at very low temperature is much shorter than twice the population relaxation time in both crystals, indicating that pure dephasing processes exist. Analyzing the results it turns out that there exsists a pure dephasing process which is temperature-independent and is very probably due to interactions between pentacene molecules, in addition to the temperature-dependent dephasing process due to the scattering of pseudolocalized phonons.
The Dehydrogenation of Cyclohexane by the Use of a Porous-glass Reactor
Authors: Shinji Osamu , Misono Makoto , Yoneda Yukio 
Published: July 2006

Abstract
The dehydrogenation of cyclohexane was studied by the use of a double tubular reactor; the inner tube was made of porous glass, and the outer tube, of non-porous glass. The Pt/Al2O3 catalyst was placed inside the inner tube. It was demonstrated that dehydrogenation proceeded beyond the equilibrium conversion to be expected in the absence of a porous tube, by separating the hydrogen produced from the central reaction zone through the porous tube. When the reaction rate was so high that the reactant gas reached equilibrium near the inlet of the reactor, the dehydrogenation conversion became greater (more than twice the equilibrium conversion) as the flow rate in the inner path decreased and the flow rate in the outer path increased. The experimental data obtained by using the porous reactor were well reproduced by a computer simulation based on a simple model, in which such parameters as the flow rate, the gas permeability, and the reaction rate, were considered. The potential application of the present porous-reactor system was also discussed.
A Displaced Harmonic Oscillator Model for the Time-resolved Emission Spectra
Authors: Fujimura Yuichi , Sato Kenji , Nakajima Takeshi 
Published: July 2006

Abstract
In a displaced harmonic oscillator model for an energy-accepting mode, analytical expressions for the time-resolved emission intensity distribution are derived for both the allowed and vibronically induced electronic transitions. In the case of the vibronically induced transition, the inducing mode as well as the accepting mode is assumed to undergo a collisional vibrational relaxation. A linear vibrational quantum-number-dependence of the electronic and collisional vibrational relaxation constants is assumed. Model calculations of the time-resolved emission-intensity distribution for a molecular system are performed using the expressions derived. The calculated time-resolved emission spectra of benzene in the vapor phase after an excitation to a single vibronic level semi-quantitatively account for the experimental results.
Laser Flash Photolysis of Benzene. IV. Physicochemical Properties of Mist Produced by Laser Excitation
Authors: Nakashima Nobuaki , Yoshihara Keitaro 
Published: July 2006

Abstract
Mist formation is observed when gaseous benzene (8–75 Torr) (1 Torr=133.322 Pa) with oxygen (\lesssim10−5–860 Torr) is irradiated by a KrF excimer laser. By measuring the falling speed, the size of droplets in the mist is determined to be 2 to 6 μm depending on gas pressure. The number of droplets produced by irradiation with a 100 mJ/cm2 pulse is estimated to be 1×105/cm3 by measuring the benzene pressure change and by turbidity measurement. The disappearance yield of benzene is 0.1 and phenol is identified with a quantum yield of 0.01. The nucleus is produced by two-photon excitation of benzene and allowed to grow into mist through a subsequent oxidation and/or polymerization reaction.