bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Theoretical Study on Bromonium Ion and Mercurinium Ion Intermediates
Authors: Yamabe Shinichi , Minato Tsutomu 
Published: August 2006

Abstract
Geometries of two title intermediates brought about by bromination and oxymercuration are studied with PM3 and ab initio molecular orbital calculations. For thirteen Br+ intermediates, the regular Markovnikov type structures are obtained and they depend upon the electronic donating strength. On the other hand, geometries of thirteen Hg(OCOCH3)2 intermediates are found to be almost the same and of the isosceles-triangle forms. Steric repulsion occurs not between two acetate groups but between one acetate and the substituents attached to olefins.
Molecular Orbital Study of Ion-Molecule Reactions Producing Hydrocarbons in Interstellar Space
Authors: Sonoda Yoko , Iwata Suehiro , Osamura Yoshihiro 
Published: August 2006

Abstract
The reaction mechanisms involving the formation of hydrocarbons in interstellar space were examined in terms of an ab initio molecular orbital calculation. The reaction energies and potential energy surfaces producing CH and C2H were evaluated based on the scheme for ion-molecule reactions proposed by the late H. Suzuki. According to the very attractive potentials of positive ions with the hydrogen molecule, most of the reactions proceed via energy-rich intermediates, such as CH4+, C2H+, C2H2+, C2H3+, and C3H+. Consequently, the model proposed by Suzuki has been confirmed concerning the result that the reactions are exothermic and without an energy barrier up to C3+ formation.
Thermodynamic Parameters for Formation of Through-Ring α-Cyclodextrin Complexes of Donor–Acceptor Linked Compounds: Comparison between D2O and H2O Solutions of Anthracene–Viologen Systems with Intramolecular Charge-Transfer Absorption Spectra
Authors: Toki Akira , Yonemura Hiroaki , Matsuo Taku 
Published: August 2006

Abstract
On the addition of α-cyclodextrin (CD), an intramolecular charge-transfer absorption band of an anthracene-viologen linked compound rapidly disappeared with elapsed time. The reason was ascribed to formation of a through-ring CD complex, which hinders direct interaction between the donor- and acceptor moieties. Thermodynamic parameters, including the energy of activation for complexation of α-CD, were evaluated by the use of the charge-transfer absorption band in D2O- and H2O solutions. Solvent deuterium isotope effects were observed with the free energy change on complexation, but not with the energy of activation for formation of the through-ring CD complex. An open, extended conformer of the linked compound was proposed as the model of the activated state for forming the through-ring CD complex.
The Formation of Crosslinked Polymer from Polyethylene in Benzenesulfonic Acid Aqueous Solution
Authors: Ishihara Yumiko , Saido Katsuhiko , Ikemura Tadashi , Takesue Tomoyuki 
Published: August 2006

Abstract
Polymer degradation was investigated by examining reactions with alternate daylight exposure and immersion in aqueous environments. Crosslinked polymers were produced by the carbonium ion reaction of carbonyl groups in benzenesulfonic acid aqueous solution.
Optical Resolution of 1-(3-Methoxyphenyl)ethylamine with Enantiomerically Pure Mandelic Acid, and the Crystal Structure of Less-Soluble Diastereomeric Salt
Authors: Sakai Kenichi , Hashimoto Yukihiko , Kinbara Kazushi , Saigo Kazuhiko , Murakami Hisamichi , Nohira Hiroyuki 
Published: August 2006

Abstract
Enantiomerically pure 1-(3-methoxyphenyl)ethylamine (1), which is a key intermediate of new phenyl carbamate drugs, was obtained by a diastereomeric method with high resolution efficiency (E) by using enantiomerically pure mandelic acid (2) as a resolving agent. The first crystallization of the mixture of diastereomeric salts from methanol gave a less-soluble diastereomeric salt in 70% yield with 99% diastereomeric excess. Recrystallization of the salt from 2-propanol gave (R)-1·(R)-2 in 97% yield with 100% diastereomeric excess (total E = 68%). The crystal structure of the less-soluble diastereomeric salt, (R)-1·(R)-2, was determined by X-ray crystallography. The crystal data are: Monoclinic, space group P21, a = 12.642(4), b = 5.890(2), c = 10.855(4) Å, β = 103.68(3)°, V = 785.4(5) Å3, Z = 2, R = 0.058 for 1450 unique reflections. The X-ray crystallography revealed that the high resolution efficiency was due to a layer-like arrangement of the enantiomerically pure acids, of which two layers sandwiched a layer of the amines by hydrogen bonds, as well as the helical column formed by hydrogen bonds between the acids and the amines, as observed for the less-soluble diastereomeric salt of 1-phenylethylamine with mandelic acid.
π-Facial Selectivity in the Diels–Alder Reaction of 5-Substituted 1,3-Cyclopentadienes
Authors: Ishida Masaru , Aoyama Takamichi , Beniya Yasufumi , Yamabe Shinichi , Kato Shinzi , Inagaki Satoshi 
Published: August 2006

Abstract
Theoretical and experimental studies are presented about π-facial selectivities in Diels–Alder reactions of 5-substituted cyclopentadienes (1). The HOMO and the NHOMO of 1 were readily predicted from the orbital mixing rule to be distorted to favor the syn- and anti-attack, respectively. The frontier orbital is dependent on the n-orbital energy (εn) of the substituent relative to the π-HOMO energy (επ) of the diene. For επ &gt; εn, the syn π-facial selectivity is predicted since the HOMO contains the diene π-HOMO as the main component. For επ &lt; εn, the anti π-facial selectivity is predicted since the π-HOMO most contributes to the NHOMO. For ε π εn, the loss of π-facial selectivity is predicted since the HOMO and the NHOMO both contribute to the reaction. The qualitative theory was examined by ab initio molecular orbital calculation on 1 (X = NH2, PH2, AsH2, OH, SH, SeH, F, Cl, and Br) and PM3 calculation of the activation energies on Diels-Alder reactions of 1 (X = NH2, PH2, AsH2, SbH2, OH, SH, SeH, TeH, F, Cl, Br, and I) with maleic anhydride. The observed selectivities of chalcogen-substituted cyclopentadienes (X = SPh and SePh) were in agreement with the theoretical prediction.
Utilization of 2,4-Di-t-butyl-6-(methoxymethyl)phenyl as a New Sterically Protecting Group
Authors: Yoshifuji Masaaki , Kamijo Kazunori , Toyota Kozo 
Published: August 2006

Abstract
A sterically hindered bromobenzene, 2-bromo-1,5-di-t-butyl-3-(methoxymethyl)benzene, was prepared and converted to the corresponding phosphonous dichloride. The dichloride was then utilized to stabilize a low-coordinate phosphorus compound such as 1-[2,4-di-t-butyl-6-(methoxymethyl)phenyl]-2-(2,4,6-tri-t-butylphenyl)diphosphene. Furthermore, the dichloride gave a cyclization product 1-chloro-2,1-oxaphosphaindan with elimination of chloromethane on standing at room temperature.
Synthesis and Properties of Polyacetylene Films Prepared by Ti(OEt)4–AlMe3 Catalyst System
Authors: Akagi Kazuo , Mochizuki Kazue , Aoki Yoshifumi , Shirakawa Hideki 
Published: August 2006

Abstract
Novel homogeneous catalyst system of composed tetraethoxytitanium–trimethylaluminum, Ti(OEt)4–AlMe3, is employed for synthesis of polyacetylene film. It is confirmed that the present system has a high catalytic activity for acetylene polymerization, and its activity is comparable to that of the representative Ti(O-n-Bu)4–AlEt3 catalyst system. Experimental conditions, especially for preparation and aging of the catalyst, are optimized in view of properties of polyacetylene film such as cis content, mechanical stretchability, and electrical conductivity. The homogeneity of the present catalyst aged at room temperature enables us to synthesize highly conductive non-stretched and stretched films whose electrical conductivities after iodine doping are 2.0 × 103 and 1.2 × 104 S cm−1, respectively. Discussion has also been made in terms of the effect of high-temperature aging for the catalyst, the role of co-catalyst as a reductant, and the dependence of electrical conductivity on film thickness.
Synthesis and Mercurophilic Properties of Sulfur-Containing Troponoid Crown Ethers
Authors: Takeshita Hitoshi , Yin Bing Zhu , Kubo Kanji , Mori Akira 
Published: August 2006

Abstract
Condensation of 2,7-dibromotropone and 7-bromo-4-isopropyl-2-(4-tolysulfonyloxy)tropone with oligoethylene glycol bis(2-mercaptoethyl) ethers gave sulfur-containing crown ether derivatives. Among these mercurophilic derivatives, triethylene glycol bis(2-mercaptoethyl) derivatives transport and extract mercury ion excellently.
Oxidative Generation of N-Acyliminium Ions from N-1-(Tributylstannyl)alkyl Carboxamides and Carbamates and Their Reactions with Carbon Nucleophiles
Authors: Narasaka Koichi , Kohno Yasushi 
Published: August 2006

Abstract
Oxidation of N-1-(tributylstannyl)alkyl carboxamides and carbamates with ammonium hexanitratocerate(IV) or ferrocenium hexafluorophosphate generates their N-acyliminium ions by the elimination of tributylstannyl radical under mild reaction conditions. The iminium ions thus formed react with various carbon nucleophiles to give the corresponding addition products.
Catalytic Asymmetric Aldol-Type Reactions Using a Chiral (Acyloxy)borane Complex
Authors: Ishihara Kazuaki , Maruyama Tohru , Mouri Makoto , Gao Qingzhi , Furuta Kyoji , Yamamoto Hisashi 
Published: August 2006

Abstract
In the presence of 20 mol% of a chiral (acyloxy)borane (CAB) complex prepared from BH3·THF and a chiral mono-O-acylated tartaric acid, achiral silyl enol ethers or ketene silyl acetals react with achiral aldehydes to afford the corresponding aldol-type adducts in good yields with high enantio- and diastereoselectivities. Furthermore, the reactivity of aldol-type reactions can be improved without reducing the enantioselectivity by use of 10—20 mol% of the CAB complex prepared from 3,5-bis(trifluoromethyl)phenylboronic acid and chiral tartaric acid derivative. The enantioselectivity can also be improved without reducing the chemical yield by use of 20 mol% of the CAB complex prepared from o-phenoxyphenylboronic acid and chiral tartaric acid derivative. The observed erythro selectivities and re-face attack of nucleophiles on carbonyl carbon of aldehydes imply that the extended transition state model is applicable.
Catalytic Decomposition of Nitrogen Monoxide over Valency-Controlled La2CuO4-Based Mixed Oxides
Authors: Yasuda Hiroyuki , Nitadori Taihei , Mizuno Noritaka , Misono Makoto 
Published: August 2006

Abstract
The direct decomposition of nitrogen monoxide (NO) to N2 and O2 was carried out over valency-controlled La2−xA′xCu1−yB′yO4 (A′ = Sr, Ba, Ca, Ce; B′ = Zr, Al) mixed oxide catalysts with a K2NiF4-type structure. The catalysts were characterized by XRD, XPS, redox titration, and oxygen TPD. It was confirmed by XPS that the surface and bulk compositions generally agreed and by redox titration that the average oxidation number (AON) of copper varied widely from 1.60 to 2.30. XPS showed that the valency of surface copper agreed with AON for AON ≤ 2, while it was in the Cu2+ state for AON &gt; 2.0. The amounts of oxygen desorbed in TPD and the oxygen nonstoichiometry of La2−xSrxCuO4 increased with x in parallel. The catalytic activity for NO decomposition showed a maximum at x = 0.4—0.5, and a good correlation was found between the catalytic activity and AON for all of the catalysts tested. The decomposition of dinitrogen oxide (N2O) was also carried out for La2−xSrxCuO4 for a comparison. Based on the much slower rate of decomposition for NO than that for N2O and the significantly high rate of oxygen TPD, it was concluded that the oxygen desorption was not the rate-determining step in the steady state. The relative activities of the catalysts studied are all well explained by a mechanism in which the active sites for NO decomposition over these catalysts are coordinatively unsaturated Cu 2+ ions on the surface that can be easily oxidized to Cu3+ upon NO adsorption.
Magnetic Properties of the Dinuclear Copper(II) Compounds Bridged by Oxalato-Type Ligands
Authors: Emori Shuji , Todoko Kyoko 
Published: August 2006

Abstract
Various dinuclear copper(II) compounds bridged by the oxalato, oxamato, and oxamidato ligands were prepared and characterized by means of magnetic susceptibility and IR spectroscopy. The strong antiferromagnetic couplings through their carboxylate or carboxamidate groups are interpreted in terms of the ligand basicities and the electron withdrawal due to the resonance of the substituents.
Enhancement of Catalytic Activity of ZnCl2 in the Friedel–Crafts Benzylation of Benzenes Using Polar Solvents
Authors: Hayashi Eiji , Takahashi Yukio , Itoh Hironori , Yoneda Norihiko 
Published: August 2006

Abstract
Zinc chloride was successfully employed in the Friedel–Crafts benzylation of benzenes as a useful catalyst in the presence of polar solvents. Particularly, zinc chloride dissolved in primary alcohols, ketones, and water with a molar ratio of 1 was a highly effective catalytic system in the reaction.
Crystal and Molecular Structure of 2-Ethylthio-3-phenyl-1,3,4-thiadiazolium Tetrafluoroborate
Authors: Matsubara Yoshio , Kitano Kazutada , Sasaki You , Yoshihara Masakuni , Maeshima Toshihisa 
Published: August 2006

Abstract
2-Ethylthio-3-phenyl-1,3,4-thiadiazolium tetrafluoroborate (2) was synthesized by the reaction of 3-phenyl-1,3,4-thiadiazole-2(3H)-thione (1) with triethyloxonium tetrafluoroborate (Meerwein’s reagent) in acetonitrile at room temperature. A structural investigation of 2 was carried out on the basis of such spectral data as 1H NMR and 13C NMR spectroscopies and X-ray analysis. The crystallographic data of 1 and 2 are as follows: Orthorhombic space group of P212121, a = 10.116(2), b = 13.199(2), c = 6.690(2) Å, V = 893.3(3) Å3, and Z = 4 for 1, orthorhombic space group of Pbca, a = 16.449(6), b = 15.291(3), c = 10.833(2) Å, V = 2725(2) Å3, and Z = 8 for 2, respectively.
Stereoselective Introduction of Hydroxyl Groups via Hydrazones
Authors: Tada Masahiro , Chiba Kazuhiro , Izumiya Koji , Tamura Mihoko 
Published: August 2006

Abstract
Reduction of tosylhydrazones by hydride reagents in wet alcohol gave predominantly alcohols whose stereochemistries are opposite to those of the major reduction products of the corresponding ketones with sodium borohydride.
Acidic Properties and Catalytic Activity of Natural Kaolinitic Clays for Friedel–Crafts Alkylation
Authors: Sabu Kuzhunellil Raghavanpillai , Sukumar Rugmini , Lalithambika Malathy 
Published: August 2006

Abstract
Natural Kaolinitic clays containing transition metals Fe and Ti in their lattice have been examined for their acidic properties and catalytic activity for the alkylation of benzene with benzyl chloride. Calcination of the clays at 550 °C and subsequent acid-activation using 2 M HCl (1 M = 1 mol dm−3) rendered the kaolinite surface highly acidic with very high acid amount. These clays exhibited high catalytic activity and selectivity for the conversion of benzyl chloride to diphenylmethane. Al(III), Fe(II), and Ti(II) ions exsolved from the lattice of kaolinites by acid activation relocate in the interlamellar space and boost the Brønsted acidity of coordinated hydroxo and proposed to initiate the alkylation. In fact kaolinites having structural transition metal, on acid activation exhibited higher acid amount and enhanced catalytic activity than kaolinites devoid of transition metals and recently studied alkylation catalysts such as synthetic TiO2–SiO2–Al2O3 and Fe2O3–SiO2–Al2O3. Natural kaolinitic clays having transition metals in their lattice possess disordered structure and hence on acid activation results in the generation of larger amounts of relocatable cations, higher surface area and higher acidity compared to an ideal kaolinite. Also their acid amount and catalytic activity retained up to five successive regeneration cycles studied.
Mobility of Charge Carriers in Sublimed Films of Phenothiazine Derivatives
Authors: Yoshida Sadamu , Kozawa Kozo , Maruyama Yusei , Uchida Tokiko 
Published: August 2006

Abstract
Mobilities of charge carriers in sublimed films of three phenothiazine derivatives, benzo[b]phenothiazine, dibenzo[a,j]phenothiazine, and triphenodithiazine, were measured in surface-type cells at room temperature in both transient and stationary phtoconduction. The drift mobilities in films of these three materials, which are the sum of electron and hole mobilities, are on the order of 10−7—10−5 cm2 V−1 s−1. They do not seem to be affected by the orientation of molecules in the sublimed films.
Discotic Liquid Crystals of Transition Metal Complexes. XVI. Discotic Mesomorphism and Unique Chromism of Bis[1,2-bis(3,4-dialkoxyphenyl)ethanedione dioximato]palladium(II) Complexes
Authors: Ohta Kazuchika , Moriya Mitsuo , Ikejima Mayumi , Hasebe Hiroshi , Fujimoto Tetsuya , Yamamoto Iwao 
Published: August 2006

Abstract
Bis[1,2-bis(3,4-dialkoxyphenyl)ethanedione dioximato]palladium(II) complexes, (abbreviated [Pd{(CnO)4dpg}2]; n = 1—12)have been synthesized and characterized. It was found that each of the [Pd{(CnO)4dpg}2] (n = 2—12) complexes has an enantiotropic discophase (Dhd). The clearing points of the [Pd{(CnO)4dpg}2] (n = 4, 8, 12) complexes are higher than those of the corresponding [Ni{(CnO)4dpg}2] (n = 4, 8, 12) complexes. Interestingly, the [Pd{(CnO)4dpg}2] complexes exhibit thermochromism and solvatochromism similar to that of [Ni{(CnO)4dpg}2] complexes.
Discotic Liquid Crystals of Transition Metal Complexes. XVII. The Mechanism of “Mesomorphic Thermochromism” in Bis(octasubstituted diphenylglyoximato)palladium(II) Complexes Established by Their Temperature-Dependent Electronic Spectra
Authors: Ohta Kazuchika , Moriya Mitsuo , Ikejima Mayumi , Hasebe Hiroshi , Fujimoto Tetsuya , Yamamoto Iwao 
Published: August 2006

Abstract
The bands in the electronic spectra of the [Pd{(C12O)4dpg}2] and [Pd{(C6)4dpg}2] complexes were assigned by using the results of temperature-dependent electronic spectral measurements. The temperature-dependent electronic spectra of “cast samples” of the complexes showed that two characteristic bands shift to higher energy (blue shift) with increasing temperature. The band which is located at a longer wavelength was assigned to the 4dz2–5pz transition (d–p band), and that located at a shorter wavelength to the metal-to-ligand charge-transfer transition (MLCT band). The absorption intensities of both bands strongly depend on the sample film preparation manners and temperatures. From these facts, the mechanism of this unique “mesomorphic thermochromism” has been established.
Dispersion and Fixation of 12-Tungstophosphate Anion on a Silica Surface Modified with Silane Agents Having an Amine Group and Their Catalytic Properties
Authors: Kamada Masahiko , Nishijima Hirotaka , Kera Yoshiya 
Published: August 2006

Abstract
Silica gel (SiO2) was modified by a dip-cure method with silane coupling agents having an amine-group: (3-anilinopropyl), (3-aminopropyl), and N-[3-(2-aminoethyl)aminopropyl] trimethoxysilanes. 12-tungstophosphate (PW12) was deposited on the carriers as a test catalyst material. The amounts and the dispersed states of the silane agents and PW12 on the modified SiO2 were successfully analysed by gravimetry as well as UV and FT-IR spectrometries. The amount of PW12 deposited increased in proportion to the amount of the silane agents on SiO2 in the case of deposition under a constant concentration of PW12-solution, although only a little PW12 was deposited directly on SiO2. The acidic site of PW12 was confirmed to interact directly with the amine-group on the modified SiO2, and the strength of the interaction was correlated with the basicity of the amine-group. The activity per gram of catalyst for the dehydration of 2-propanol as a test reaction is generally higher than that on a directly deposited one, although the activity per PW12 unit certainly decreases with the SiO2-modification. The activity was confirmed to increase by a pretreatment at high temperatures, such that the amine-group was completely decomposed. It was clearly shown that the present modification method could be effectively applied for preparing a highly dispersed heteropoly acid catalyst on carriers.
Efficient :CF2 Generation by IR Multiphoton Dissociation : Time Resolved Observation of Infrared Chemiluminescence from the :CF2 + O2 → COF2 + O Reaction
Authors: Chowdhury Pradyot Kumar 
Published: August 2006

Abstract
IR multiphoton dissociation of Octafluorocyclopentene is used as an efficient means for the generation of :CF2. Time resolved infrared chemiluminescence has been observed from the reaction of ground state :CF2 (X1A1) radicals with molecular oxygen, generating COF2 as a product. IR emission observed around 5 μm region has been assigned to ν1 and 2ν2 modes of COF2. The kinetic measurements of the reaction as a function of oxygen pressure suggest a rate constant to be 5 × 1011 cm3 mol−1 s−1, which corresponds to a :CF2 temperature of ≤3650 K.
Hydrates of Organic Compounds. XVIII. The Formation of Hydrates of Tetraisopentylammonium Salts Having Polyanions
Authors: Nakayama Haruo , Baba Kei 
Published: August 2006

Abstract
In order to confirm the formation of hydrates, both the solid–liquid phase diagrammatic method and the thermal analytic method using a differential scanning calorimeter were applied to binary mixtures of water with various tetraisopentylammonium salts having polyanions, poly(vinyl sulfate) anion and poly(styrenesulfonate) anion, as well as related low molecular-weight anions, ethyl sulfate ion and p-ethylbenzenesulfonate ion. It was found that the two salts with the polyanions and ethanesulfate could form hydrates with large hydration numbers: The melting point and hydration numbers were estimated to be around 16.5 °C and 34 ± 2 for the tetraisopentylammonium poly(vinyl sulfate) hydrate; around 11 °C and 35 for the tetraisopentylammonium poly(styrenesulfonate) hydrate; and 12—13 °C and 37 ± 2 for the tetraisopentylammonium ethyl sulfate hydrate, respectively. The formation of the hydrate phase around the tetraisopentylammonium cation attached to a surface of cation-exchange resins was also examined.
Investigation of Electron Transfer through the Interfacial Electrical Double Layers of Various Micelles
Authors: Fujihira Masamichi , Yanagisawa Masahiro , Kondo Toshihiro 
Published: August 2006

Abstract
In order to estimate the inner potential difference of an electrical double layer (EDL) created between the ionic hydrophilic head group of the amphiphile and its counter ion, the electrochemical characteristics of the ferrocene derivatives solubilized in three kinds of micelles were measured, and are discussed so as to clarify the effect of the EDL on the electron transfer through the interface.
Unimolecular Dissociation of Benzyl Halide Radical Anions Studied by Low-Temperature Pulse Radiolysis
Authors: Kimura Norio , Takamuku Setsuo 
Published: August 2006

Abstract
The one-electron reduction of benzyl halides (BzX; X = F, Cl, Br) by solvated electrons in 2-methyltetrahydrofuran has been investigated by using a pulse radiolysis technique at different temperatures above 77 K. The radical anions of BzX (λmax = 300 nm) formed by the capture of an electron in the π*-orbital of the benzene ring dissociate into Bz· (λmax = 320 nm) and X− via Bz•/X− complexes (λmax = 340 nm for BzCl and 370 nm for BzBr). The corresponding species were observed with 4-phenylbenzyl halide at 85 K and below. A spectral change observed at 95 K has been attributed to a structural change of the biphenylyl group. The dissociation rate of the radical anions increased in the order BzF &lt; BzCl &lt; BzBr. On the basis of these results, the reaction mechanism is discussed.