bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic Studies on the Strictly Catalytic Acetylation of Mesitylene with Acetic Anhydride by HCl and Metal Chlorides in Acetic Acid
Authors: Yamanaka Tohr , Imai Takashi 
Published: July 2006

Abstract
On the acetylation of mesitylene (1, 0.5–1 mol dm−3) with acetic anhydride (Ac2O, 0.5–1.5 mol dm−3) at 30–90 °C in acetic acid as solvent, SbCl5, FeCl3, SnCl4, or ZnCl2 (each of 0.02–0.2 mol dm−3) under the co-catalytic effect of HCl (0–0.75 mol dm−3) showed a continuous catalytic activity. The product was exclusively 2′,4′,6′-trimethylacetophenone for conversions of 1 in the range of 0–90%. The reaction was first order with respect to 1 and Ac2O. The rate constants were proportional to 1–1.4th power of the concentration of the metal chloride. The apparent activation energy was 18.8 kcal mol−1 for all the catalysts. The catalytically active species are thought to be the conjugate acids from the metal chloride and HCl. Relative catalytic activities of the metal chlorides varied in parallel with their relative Lewis acid-strengths.
ESR and ENDOR Studies of Azulenophane Anion Radicals
Authors: Iwaizumi Masamoto , Fukazawa Yoshimasa , Kato Nobuo , Itô Shô 
Published: July 2006

Abstract
The anion radicals of syn- and anti-[2.2](2,6)azulenophane, (1) and (2), [2.2](1,3)azulenophane, (3), and [2](1,3)-azuleno[2]paracyclophane, (4), all produced by alkali metal reduction in various solvents, have been investigated by ESR and ENDOR spectroscopy. They exist in the ion pair with cations in the solutions, except for 4\ewdot which exists in 1,2-dimethoxyethane with Na+. Their ion pairing tendency is appreciably higher than that of the naphthalenophane anion radicals. The unpaired electron in these ion pairs localizes mostly on an azulene ring (in 1\ewdot, 2\ewdot, and 3\ewdot, close to a cation). The polarization effects due to the pairing with the cations are much larger than those in the naphthalenophane anion radicals, and increase in the order 1\ewdot≤2\ewdot≤3\ewdot, indicating that the smaller the inter-layer orbital overlap, the larger the polarizability. The unpaired electron of 4\ewdot localizes mostly on the azulene ring even in the free anion.
Theoretical and Experimental Studies of the Membrane Permeabilities to Ions in Liquid Membrane
Authors: Nomura Kazuo , Matsubara Akira , Kimizuka Hideo 
Published: July 2006

Abstract
A theory for the ion transport across liquid ion-exchange membrane was presented on the basis of nonequilibrium thermodynamics with the assumptions that the carrier ions and complexes were present only in the membrane phase, and that there was no volume flow and all chemical reactions were at equilibrium. The equations for “total” fluxes of membrane-permeable ions at steady state were derived from a set of the equations for “individual” fluxes of all mobile species present in the liquid membrane where the complexes were assumed to be partially dissociated. The “total” phenomenological coefficients were able to be expressed in terms of the “individual” coefficients. The diffusional and electroconductional membrane permeabilities to a selective ion in the liquid membrane–single electrolyte system were found to be in the same form as those in the fixed-site membrane–single electrolyte system, if the mean diffusion coefficient and mean mobility of the free species and its complex were used. The rate constants in the permeation process were also related to the diffusional membrane permeability. The experimental examination was made on a liquid cation-exchange membrane–aqueous single electrolyte system at 25 °C. The solution of calcium hexadecyl sulfate in 1-octanol and calcium chloride were used as the liquid membrane and the electrolyte, respectively. All the measured quantities were consistently interpreted by the presented theory.
Reduction-Reoxidation Behavior of Silver(I) Ions in X-Type Zeolites
Authors: Iwamoto Masakazu , Hashimoto Tsuneyasu , Hamano Toshikazu , Kagawa Shuichi 
Published: July 2006

Abstract
The reduction of Ag+ ions in X zeolites by hydrogen, the reoxidation of Ag atoms by oxygen, and the formation of silver particles were studied kinetically. The reduction is suggested to be a catalyzed reaction requiring an activation of hydrogen at some specific sites on the basis of the influence of exchange levels and hydrogen pressures on the reduction rates. At elevated temperatures the reduction of Ag+ ions proceeded quantitatively and resulted in formations of Ag particles with a diameter between 10 and 25 nm and of highly dispersed Ag clusters. The clusters were easy to be reoxidized by oxygen at 473 K or below, while the particles were difficult to revert into the zeolite matrix. The diameter of the Ag particles was dependent on the reduction temperature and ion-exchange level and independent on the reduction time. It is discussed that this is due to the slow nucleation and the fast nuclear growth of Ag particles.
Intermolecular Potential, Vibrational Spectra, and Structures of Amino Acid Crystals. I. Distortion of Molecules and Equilibrium Crystal Structure
Authors: Machida Katsunosuke , Kuroda Yoshihiro 
Published: July 2006

Abstract
A general method of the crystal packing optimization is developed for the molecular crystals consisting of non-rigid molecules. The intramolecular potential is described as a general harmonic force field in terms of a suitable set of internal symmetry coordinates, and the intermolecular potential as a sum of the pairwise atom-atom interaction terms. The adjustable structure parameters are those among the six cell constants, a, b, c, α, β, and γ, and the translations and the rotations of the molecules which maintain the crystal symmetry. The intermolecular force is separated into two parts, one of which determines the location of the center of mass and the orientation of the principal axes of each molecule and the other leads to a certain molecular distortion. The calculated distortion may be used, in addition to the difference between the calculated and the observed crystal structures, as a check point of the reliability of the model potential. The importance of this separation in the rigid molecule approximation is pointed out.
Sublimation Behavior of Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)lanthanoid(III)
Authors: Amano Ryohei , Sato Akiko , Suzuki Shin 
Published: July 2006

Abstract
Two fundamental experiments (to determine vapor pressures and vacuum sublimation-recrystallizing temperature zones) were undertaken on a series of remarkably volatile and thermally stable lanthanoid(III) chelates of 2,2,6,6-tetramethyl-3,5-heptanedione (Ln(thd)3) in order to obtain information about their sublimation behavior. Vapor pressures of these chelates were measured from 100 to 150 °C by means of a modified Knudsen effusion technique. Vacuum sublimation-recrystallizing temperatures were determined by using a sublimation apparatus with a continuous temperature gradient along its sublimation tube. The obtained enthalpies of sublimation were classified into three groups (La to Gd, Tb and Dy, and Ho to Lu), and the vacuum sublimation-recrystallizing temperature zones were divided into two sets (La to Tb, and Dy to Lu). The Tb and Dy chelates were also found to change thermally from a dimeric form to a monomeric form at a definite temperature. These results are explained in terms of the two different crystallizing forms of Ln(thd)3 chelates. Furthermore, the regularity in their sublimation behavior is discussed as a function of the atomic numbers of the lanthanoid metals, using thermochemical considerations.
The Temperature Dependence of the Trapped and Averaged-valence State in Mono-oxidized Dialkylbiferrocenes
Authors: Iijima Sei’ichiro , Saida Ritsuko , Motoyama Izumi , Sano Hirotoshi 
Published: July 2006

Abstract
An interesting temperature dependence of the valence state was observed in the Mössbauer spectra of the mixed-valence salts of 1′,1'″-dialkylbiferrocenes, measured at various temperatures from 4.2 K to 300 K. A mechanistic consideration of the temperature dependence has been carried out assuming a conformational change of the monocation salts induced both by the variation in the temperature and by the kind of counter anion.
Oxidation-Reduction Properties of Mixed Oxides in the Cerium–Uranium–Oxygen System
Authors: Tagawa Hiroaki , Fujino Takeo , Watanabe Kenju , Nakagawa Yumiko , Saita K\={o}ji 
Published: July 2006

Abstract
The formation and the oxidation-reduction properties of mixed oxides in the Ce–U–O ternary system were examined by means of thermogravimetry and the X-ray diffraction technique. The mixed oxides were prepared by the reactions of CeO2 with U3O8 in air and in hydrogen. The composition of the products heated in air, followed by slow cooling to room temperature, was approximately expressed by this equation: yCeO2+(1–y)UO2.67. By X-ray diffraction, it was shown that the oxides formed at 1100 °C in air were mixtures of Ce0.6U0.4O2.3 and α-U3O8 in the y&lt;0.6 range, while they were in single phases of solid solutions for y≥0.6. When the mixed oxides, MO2+X, where M indicates yCe+(1–y)U, were re-heated in air, weight loss due to oxygen liberation was observed above 500 °C, and it was enhanced with a rise in the temperature. The hydrogen reduction of the oxides proceeded in two steps; the first step was the reduction of MO2+X to MO2 below 600 °C, and the second one was the reduction of MO2 to MO2−X above 600 °C. The composition of the oxides obtained can be given by this equation: yCeO1.81+(1–y)UO2.00. Two separate linear relationships for the lattice parameter of the fluorite-type structure as a function of the cerium content were obtained; one is applicable to the solid solutions with y≤0.6, where the lattice parameter is nearly that of UO2, and the other to the solid solutions with y≥0.4. The latter obeys Vegard’s law between UO2 and CeO2. The oxides with y=0.4–0.6 were in the two-phase region of the solid solutions.
The Solution Chemistry of Organotin Compounds. I. A 1H NMR Study of the Complex Formation between Methyltin Trichloride and 4-Substituted Pyridines
Authors: Fujiwara Hideaki , Sakai Fumihiko , Takeyama Miyoko , Sasaki Yoshio 
Published: July 2006

Abstract
The formation of donor-acceptor complexes between MeSnCl3 and 4-substituted pyridines has been investigated by analyzing the concentration dependence of NMR parameters. The formation of 1(MeSnCl3):2(pyridine) and 1:1 complexes has been proved, and the equilibrium constants(K1 and K2) and complex formation shifts (ΔAB and ΔAB2) are determined for the successive formation of these complexes, logK1 and logK2 are in a good linear correlation with each other, and they have a tendency parallel with that of pKa of the pyridine derivative, suggesting a predominant contribution of σ-bonding in the donor-acceptor bond. Both ΔAB and ΔAB2 indicate a high-field shift on the formation of the complex, which is consistent with the expected electron transfer in the donor-acceptor bond. However, ΔAB varies inversely to the basicity of the pyridines; the anisotropy effect of the pyridine ring is suggested as the reason for this. The results are also discussed in relation to Hammett’s substituent constant.
The Thermal Decomposition of Sodium Nitrate and the Effects of Several Oxides on the Decomposition
Authors: Hoshino Yoshio , Utsunomiya Taizo , Abe Osami 
Published: July 2006

Abstract
The thermal decomposition of sodium nitrate and the effects of several oxides, such as silica, titania, zirconia, alumina, and magnesia, on the decomposition were studied up to 900 °C by means of the thermal analysis, gas analysis, and chemical analysis of the reaction products. The reaction of sodium nitrate and silica was especially investigated in some detail over a wide composition range. The thermal decomposition of sodium nitrate started at about 450 °C. The gases formed were O2, NO, and N2, the formation of N2 being detected above 680 °C The thermal decomposition of sodium nitrate was supposed to consist of the following three successive or concurrent reaction processes, according to the degree of the reaction: (I) the decomposition of sodium nitrate to nitrite and oxygen, (II) the first-order liquid-phase reaction, with some kind of quantitative relationship between nitrate and nitrite, and (III) the formation reaction of sodium oxide, expressed by the Avrami-Erofe’ef equation. The (II) and (III) reaction processes can be reasonably interpreted if the existence of the peroxide ion is assumed. Acidic oxides, such as silica and titania, were supposed to lower the activation energy of the (III) reaction process by forming stable salts with sodium nitrate and/or its intermediate reaction products. The effects of these oxides on the thermal decomposition of sodium nitrate could be interpreted by the relative scale of the acidity of oxides.
The Conformational Analysis of a Series of 4,8-Dimethyl-6-phenyl-5,6,7,8-tetrahydro-4H-1,3,2,6-dioxathiazocine 2-Oxides Using NMR
Authors: Nishiyama Tomihiro , Nakai Yasushi , Shishibori Hideaki , Yamada Fukiko 
Published: July 2006

Abstract
The title compounds were prepared, and their 1H- and 13C-NMR spectra were examined. On the basis of the data for the benzene–solute collision complexes and the magnitudes of the γ shifts, five isomeric conformations of the compounds were discussed.
The Methylation of Nucleic Acids. The Analysis of Methylated Ribonucleosides by Means of High-performance Liquid ODS–Silica Gel and Cation-exchange Chromatography
Authors: Tanabe Toshizumi , Yamauchi Kiyoshi , Kinoshita Masayoshi 
Published: July 2006

Abstract
The quantitative determination of adenosine, guanosine, inosine, cytidine, uridine, and their methylated derivatives was studied by means of a high-performance liquid chromatographic method using ODS–silica gel cation-exchange, and anion-exchange resins as column packings. The method was apphed to the analysis of yeast-RNA, which was methylated by trimethyl phosphate at pH 7 and 9.
Asymmetric Reduction of Aromatic Ketones with Reagents Prepared from NaBH4 and ZnCl2 in the Presence of 1,2 : 5,6-Di-O-isopropylidene-α-d-glucofuranose
Authors: Hirao Akira , Ohwa Masaki , Itsuno Shinichi , Mochizuki Hidenori , Nakahara Seiichi , Yamazaki Noboru 
Published: July 2006

Abstract
Asymmetric reduction of prochiral aromatic ketones using a freshly prepared complex derived from NaBH4, 1/3 equiv of ZnCl2, and 1,2 : 5,6-di-O-isopropylidene-α-d-glucofuranose (1) gives an excess of the corresponding (S)-alcohols in substantial optical yields (28–68%). The effects of the NaBH4/ZnCl2/1 ratio, temperature, solvent, structure of various monosaccharide derivatives, and the metal cation of the reagent on the optical yields were examined.
The Extraction of the Tungsten(VI)–Pyrocatechol Violet Complex with Tridodecylethylammonium Bromide
Authors: Shijo Yoshio , Shimizu Tokuo , Sakai Kaoru 
Published: July 2006

Abstract
The extraction equilibria and the fundamental conditions were studied for extracting the tungsten(VI)–Pyrocatechol Violet complex anion in a form of an ionic associate with tridodecylethylammonium salt in carbon tetrachloride. The ternary complex has an absorption maxima at 575 nm in the organic phase. The optimum pH range for the extraction is 4.8–5.6. The distribution ratio and the molar absorptivity are 3.3×102 and 4.7×104 dm3 mol−1 cm−1 respectively. The composition of the ternary complex is estimated to be WO2(PV)2(R3R′N)2.The extraction constant would be:
K ex=\frac[WO2(PV)2(R3R′N)2]o[WO2(PV)22−][R3R′N+]2.
It is given by logKex=13.56. Many foreign cations can be masked with CyDTA.
The Reaction of 2-Ethoxy-1,3-dithiolane with Carbonyl Compounds
Authors: Jo Shigeo , Tanimoto Shigeo , Oida Tatsuo , Okano Masaya 
Published: July 2006

Abstract
The reaction of 2-ethoxy-1,3-dithiolane with carbonyl compounds such as aldehydes and ketones was investigated. The reaction proceeded smoothly in the presence of the HgCl2-catalyst to afford 2-substituted and 2,2-disubstituted 1,3-dithiolanes. The reaction also offers an interesting alternative to the previously reported methods of synthesizing 1,3-dithiolanes which involve the acid-catalyzed reaction of carbonyl compounds with 1,2-ethanedithiol.
Intramolecular Cyclization of Nerol and the Related Attack of (Z)-Allylic Alcohol Moiety on the Terminal Olefin Linkage as Induced by TiCl4–PhNHMe Complex. Synthesis of Nezukone
Authors: Itoh Akira , Saito Tadashi , Oshima Koichiro , Nozaki Hitosi 
Published: July 2006

Abstract
Nerol was cyclized to terpinyl chloride or bromide in the presence of TiX4–PhNHMe (1 : 1) complex (I, X= Cl, Br) in dichloromethane at −23 °C, geraniol being converted into geranyl halide by simple halogenation. Terminally modified derivatives YCH2C(Me)=CHCH2CH2CMe=CHCH2OH (Y=SiMe3, SnBu3) of (2Z,6E) configuration were cyclized by treatment with I to afford limonene in high yields and 100% selectivity. Cyclization of (2Z) isomers of CH2=CR–CH2CH2CMe=CHCH2OH (R=H, Me, Cl) produced seven-membered carbocyclic products in fair yields. The novel procedure has been utilized in the synthesis of nezukone from (2E)-3-isopropyl-2,6-heptadien-1-ol involving five steps.
Tellurium-catalyzed Carbonylation of Amines with Carbon Monoxide
Authors: Kambe Nobuaki , Kondo Kiyoshi , Ishii Hideo , Sonoda Noboru 
Published: July 2006

Abstract
Carbonylation of amines with carbon monoxide was catalyzed by tellurium to produce corresponding urea derivatives, formamides, and molecular hydrogen. The urea formation proceeds according to the equation; 2RNH2+CO→(RNH)2CO+H2. The successful achievement of the catalytic formation of urea derivatives would be due to the thermal instability of hydrogen telluride which decomposes to generate elemental tellurium and hydrogen. The formation of formamides and hydrogen was found to be suppressed by the addition of nitrobenzene which did not affect the urea formation. Effects of the reaction time, temperature, pressure of carbon monoxide, and additives on this carbonylation reaction are discussed.
Reactivities of Stable Rotamers. VI. Manifestation of Differential Reactivities of the Methyls in a t-Butyl Group in Radical Halogenations
Authors: Seki Shigetaka , Morinaga Tsutou , Kikuchi Hiromi , Mitsuhashi Tsutomu , Yamamoto Gaku , Oki Michinori 
Published: July 2006

Abstract
The methyls in a t-butyl group are shown to exhibit different reactivities in radical halogenations, if rotation about a (CH3)3C–CXY2 bond is frozen. Barriers to rotation of halogenated 9-t-butyl-1,2,3,4-tetrachlorotriptycenes are obtained as ΔH\eweq ca. 32 kcal/mol. The cause of the selectivity in chlorination with sulfuryl chloride was discussed by obtaining reactivity data with a variety of compounds and halogenating reagents. It is concluded that the neighboring group participation of the peri-halo substituent is responsible for the observed selectivity.
Kinetic and Equilibrium Studies on Substitution Reactions of the Chlorobis(β-diketonato)manganese(III) Complexes with Other β-Diketones
Authors: Ito Yoshiaki , Kawaguchi Shinichi 
Published: July 2006

Abstract
The MnCl(β-dik)2 complexes, where β-dik stands for an anion of acetylacetone, benzoylacetone, and dibenzoylmethane, were confirmed to have the five-coordinate structure in dichloromethane and their adduct formation constants with various donor solvents were measured. Equilibria and kinetics of substitution reactions of MnCl(β-dik)2 with other β-diketones were determined by the spectrophotometric method and the mechanism for these reaction is proposed.
Singlet-excitation Migration in Pure Liquid Methyl- and Ethylnaphthalenes
Authors: Ohno Takeshi , Kato Shunji 
Published: July 2006

Abstract
The fluorescence quenching of solvent molecules and solute molecules was studied in the alkylnaphthalene solvents. The singlet-excited states of the solvent molecules were quenched by 1,4-bis(trichloromethyl)benzene with the rate parameter of 2.8×1010 mol−1 dm3 s−1 at 45 °C. This rate parameter is twelve times as great as that of the solute, dibenz[a,c]anthracene, in the solvent, 1-methylnaphthalene. The diffusion constant of the excitation migration of the solvent molecule is calculated to be larger (0.35×10−4 cm2 s−1 at 45 °C) than that (0.03×10−4 cm2 s−1) of the solute. The temperature coefficient (22 kJ/mol) of the excitation migration is too small to explain the migration mechanism on the hypothesis of the “successive association-dissociation reaction of excimer” proposed by Birks. The presence of a short-range exciton in the liquid is likely.
An Ab Initio Calculation of the Electronic Structure of the [Co(CN6)]3− Ion
Authors: Sano Mitsuru , Hatano Yasuyo , Kashiwagi Hiroshi , Yamatera Hideo 
Published: July 2006

Abstract
Ab initio LCAO MO SCF calculations were carried out on [Co(CN)6]3−. The character of the wave-functions was discussed in terms of the orbital-mixing rule. The radial distribution of electron density obtained from molecular orbital (MO) calculation was compared with that obtained from X-ray experiments. On the ionization from a metal d-orbital, a significant electronic relaxation was shown to occur, which makes Koopmans’ theorem invalid. The calculated excitation energies without a configuration interaction showed a qualitative correspondence with the absorption spectrum.
The CD Spectra of Carbonato Complexes of the [Co(CO3)(O,O)(N)2]− and [Co(CO3)(N)4]+ Types and Related Diaqua Complexes
Authors: Tsuji Kenshi , Fujinami Shuhei , Shibata Muraji 
Published: July 2006

Abstract
Five carbonato complexes, [Co(CO3)(ox)(tn)]−, cis-[Co(CO3)(ox)(py)2]−, cis·cis-[Co(CO3)(NH3)2(py)2]+, cis-[Co(CO3)(en)(py)2]+, cis-[Co(CO3)(NH3)2(bpy)]+, and two related complexes, cis-[Co(ox)(NH3)2(en)]+ and cis-[Co(mal)(NH3)2(en)]+, have been prepared and resolved. The solution CD spectra of these resolved complexes and those of diaqua complexes derived from the carbonato complexes have been measured. The CD spectral comparison in the first absorption band (T1g-band) region has suggested a relation in the sign of the Cotton peak between each of the carbonato complexes and the corresponding diaqua complex. Based on this relation, the assignments of the absolute configurations for the present complexes have been established.
Spectrophotometric Determination of Iron(III) with N,N′-Bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic Acid
Authors: Katsuyama Tetsuo , Kumai Toshihiko 
Published: July 2006

Abstract
N,N′-Bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (hbed) reacts with iron(III) to form a red complex having an absorption maximum at 485 nm. The iron(III) complex is so stable that the maximum absorbance of the solution is constant over the pH range from 2.5 to 13.2 and a large excess of reagent is not necessary. Beer’s law is obeyed up to 1.6×10−4 mol dm−3 (9 μg cm−3) of iron(III). The molar absorption coefficient is 3.95×103 1 cm−1 mol−1, and the relative standard deviation for determination of 3.5 μg cm−3 of iron was 0.29%. The molar ratio of iron(III) to hbed was found to be 1 : 1. The effect of 32 diverse ions was examined; only colored aqua metal ions interfere. The present method was applied to the determination of iron in aluminium alloys.
Wet Oxidation of Water-soluble Polymers
Authors: Imamura Sei-ichiro , Tonomura Yoshiaki , Kawabata Nariyoshi , Kitao Takane 
Published: July 2006

Abstract
Wet oxidation of various water-soluble polymers was carried out with particular attention given to the reactivity of polyethylene glycol. Polymers with high molecular weight were more reactive than their low molecular weight analogues or monomer models. It is suggested that the high reactivity of the polymers can be attributed to the ease of an intramolecular hydrogen abstraction in the propagation step of oxidation. Bio-degradability of the polymers was highly improved by wet oxidation. Wet oxidation is especially effective for the treatment of waste water containing water-soluble polymers.