bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inversion at Selenium in [MIII(RSeCH2CH2NH2){N(CH2CH2NH2)3}]3+(MIII=Co, Rh; R=CH3, CH3CH2, C6H5CH2) and [Co(CH3SeCH2COO){N(CH2CH2NH2)3}]2+
Authors: Nakajima Kiyohiko , Tozaki Katsuhiko , Kojima Masaaki , Fujita Junnosuke 
Published: July 2006

Abstract
The selenoether (selenide) complexes, t-[Co(RSeCH2CH2NH2)(tren)]3+ (t=trans(tertiary amine nitrogen, Se); R=CH3, CH3CH2, C6H5CH2; tren=tris(2-aminoethyl)amine), p-[Rh(CH3SeCH2CH2NH2)(tren)]3+ (p=cis-(tertiary amine nitrogen, Se)), and t-[Co(CH3SeCH2COO)(tren)]2+ were prepared and resolved for the first time by the chemical or SP-Sephadex column chromatographic method. Racemization of these complexes in aqueous solutions was studied at an ionic strength of 0.25 (NaClO4) in the pH and temperature ranges of 4.00–6.91 and 0.25–33.50 °C, respectively. The racemization rates were independent of pH and an intramolecular inversion mechanism was suggested. The ΔG25°C\eweq values for inversion of t-[Co(RSeCH2CH2NH2)(tren)]3+ decreases in the order of CH3 (95.2 kJ mol−1)&gt;CH3CH2 (89.4)&gt;C6H5CH2 (87.7), while the ΔH\eweq values are almost the same (95–97 kJ mol−1). The variable-temperature 13C NMR study of p-[Co(CH3SeCH2CH2NH2)(tren)]3+ yielded the inversion rate constant, 10 s−1 at the coalescence temperature (ca. 60 °C), which is much larger than that of the corresponding t-isomer (8.5×10−3s−1 at 60 °C). The difference in inversion rate between the isomers seems to be related to the steric crowding around the Se-R group of the complex. The rhodium(III) complex racemizes slower than the corresponding cobalt(III) complex. The values of thermodynamic parameters for t-[Co(CH3SeCH2COO)(tren)]+2 are nearly the same as those for t-[Co(CH3SeCH2CH2NH2)(tren)]3+.
The Structure–Reactivity–Chemoselectivity Relationship on the Reactions of 1-Unsubstituted Tautomeric 2-Pyridones with Benzyne
Authors: Kuzuya Masayuki , Noguchi Akihiro , Mano Ei-ichi , Okuda Takachiyo 
Published: July 2006

Abstract
The reactions of 2-pyridones with benzyne were investigated in order to gain some insight into the structure–reactivity–chemoselectivity relationship involved in the tautomeric systems. All reactions examined have resulted in the formation of Diels-Alder and Michael-type adducts. It has been shown that the Diels-Alder reactivities were well correlated with the HOMO energy levels of the 2-pyridone form and the yields of the Michael-type adduct were closely associated with the tautomeric equilibria. In summary, the chemoselectivities of 2-pyridones in the reaction with benzyne were largely affected by the tautomeric properties.
An Improved Method for Synthesis of l-Homoglutamic Acid via Epsilon-N-deamination of l-Lysine Derivative
Authors: Kondo Michio , Miyazaki Koujiro , Kodama Hiroaki , Horimoto Hideaki 
Published: July 2006

Abstract
A convenient procedure to prepare l-homoglutamic acid (l-2-aminoadipic acid; l-Aad) is described. Chlorination of ε-amino group in acetyl-l-lysine ethyl ester with t-butyl hypochlorite (t-BuOCl) followed by dehydrochlorination with pyridine gave ethyl 5-cyanovalerate which on acid hydrolysis afforded l-Aad in good yield.
The Photolysis of N,O-Diacyl-N-phenylhydroxylamines
Authors: Sakurai Tadamitsu , Yamamoto Hirofumi , Yamada Shuichi , Inoue Hiroyasu 
Published: July 2006

Abstract
The photochemical decomposition of the title compounds yielded the rearrangement products derived from 1,3- and 1,5-aroyloxyl migrations in addition to the fragmentation products typical of the aroyloxyl and amido radicals, while only 1,3-aroyloxyl migration was observed on thermolysis. The results of crossover experiments indicate an intramolecular rearrangement, probably involving homolysis of the N–O bond in the excited states. Triplet quenching studies demonstrate that the rearrangement and fragmentation proceed exclusively via the first excited singlet state. No formation of the rearrangement products on triplet sensitization was explained on the basis of the spin multiplicity effects on a radical–radical recombination process within a solvent cage.
Preparation and Enzymatic Hydrolysis of Polymers Anchoring Biphenyl-2-ol
Authors: Ishikawa Tomomichi , Tanaka Youji 
Published: July 2006

Abstract
Polymers anchoring fungicidal biphenyl-2-ol(BPOL) were prepared by the polymerization and copolymerization of 2-biphenylyl methacrylate(BPMA) with various comonomers such as styrene, vinyl acetate, 2-hydroxyethyl methacrylate, N-methacryloylglycine, and N-methacryloyl-Dl-alanine. The reactivity ratios of BPMA with the comonomers were evaluated. The α-chymotrypsin-catalyzed hydrolysis of the polymers was also studied. The release of BPOL from the polymers was represented by means of the Michaelis constant Km and the catalytic-rate constant kcat. The BPMA homopolymer gave higher Km and kcat values than the copolymers, and the copolymers with a higher content of substrate units underwent cleavage more readily. It was found that the hydrolysis of the polymeric substrates is affected by the structure and character of the comonomer rather than the arrangement order of the repeating monomer units in the polymer sequence.
Synthesis of Homoallylic Alcohols from Allylic Phosphates and Aldehydes with Organoaluminum Reagent Containing Al–Sn Linkage
Authors: Matsubara Seijiro , Wakamatsu Kuni , Morizawa Yoshitomi , Tsuboniwa Noriyuki , Oshima Koichiro , Nozaki Hitosi 
Published: July 2006

Abstract
Treatment of allylic phosphates with the reagent prepared from n-Bu3SnLi and Et2AlCl or from SnF2 and Et2AlCl affords allyltin compounds which react with aldehydes to produce homoallylic alcohols in good yields. The formation of allyltin compounds requires the catalytic amount of Pd(PPh3)4 and proceeds with inversion of the stereochemistry predominantly.
Mean Square Deviations of Interatomic Distances in Liquid Carbon Tetrachloride
Authors: Nishikawa Keiko , Iijima Takao 
Published: July 2006

Abstract
In simulating the X-ray scattering intensity of liquid carbon tetrachloride, the structural diffusion model for the bcc local structure has been refined by formulating the mean square deviations of interatomic distances by dividing them into two parts, namely, translational and rotational contributions. By this treatment, the simulation has not been improved in comparison with the modified Prins relation, but the description of the motion of carbon tetrachloride molecules in the liquid becomes clear. The degree of depolarization of the ν1 Raman line is well accounted for by the use of the translational mean square deviations determined.
The Structure of the Cyclodextrin Complex. XVIII. Crystal Structure of β-Cyclodextrin–Benzyl Alcohol (1:1) Complex Pentahydrate
Authors: Harata Kazuaki , Uekama Kaneto , Otagiri Masaki , Hirayama Fumitoshi , Ohtani Yoshiro 
Published: July 2006

Abstract
The crystal structure of the β-cyclodextrin–benzyl alcohol (1:1) complex pentahydrate was determined by the X-ray diffraction method. The crystal is monoclinic with the space group P21, Z=2, a=15.356(3), b=10.101(2), c=20.869(3)Å, and β=109.90(1)°. The structure was solved by an inspection of a Patterson map and a trial-and-error method combined with a rigid-body least-squares technique. The structure was refined using the block-diagonal least-squares method to an R-value of 0.066 for 5290 reflections (sinθ⁄λ&lt;0.63). The β-cyclodextrin molecule is somewhat elliptically distorted from the regular heptagonal symmetry because of the inclusion of a planar molecule. One primary hydroxyl group shows a gauche-trans conformation, while the others are in a gauche-gauche conformation. The secondary hydroxyl groups form intramolecular O(2)–H···O(3′) or O(3′)–H···O(2) hydrogen bonds, which maintain the round structure of β-cyclodextrin. The guest benzyl alcohol molecule is fully enclosed within the host cavity. Water molecules are distributed in intermolecular spaces between β-cyclodextrin molecules. The phenyl group of the guest is located at the primary hydroxyl side of the cavity. The hydroxyl group occupies a position at the secondary hydroxyl side of the cavity, and forms hydrogen bonds with adjacent β-cyclodextrin molecules. β-Cyclodextrin molecules are stacked along the b axis to form a typical cage-type structure with a herringbone-like packing pattern.
CO2 Laser-induced Decomposition of 1,2-Dichloro-1-fluoroethane
Authors: Ogura Hiroo , Yano Takayuki 
Published: July 2006

Abstract
CH2ClCHFCl was photolyzed with a TEA CO2 laser at 1033.5 cm−1. The infrared multiphoton dissociation mechanism of CH2ClCHFCl was investigated under various conditions: Sample gas pressure, additive gas pressure, pulse number, pulse energy, and pulse duration. It is concluded that primary process of the IRMPD is direct elimination of molecular HCl and HF, HCl elimination being predominant channel. Primary HCl elimination products cis-and trans-CHF=CHCl, and CH2=CFCl are formed at high vibrational levels, from which additional photon absorption occurs in the secondary photolysis to give rise to CH≡CCl, CH≡CF, and CH2=CHF. All of the secondary products are concluded to be derived from mainly CH2=CFCl among the chlorofluoroethene isomers. CH2=CFCl decomposes via HF and HCl elimination channels together with the C–Cl bond-rupture channel. CH≡CH appears to be generated by the H atom abstraction reaction of C2H· radical, which may result from further decomposition of CH≡CCl and/or CH≡CF. The neat IRMPD at higher pressures gives quite similar primary product distribution, but markedly different secondary product distribution from those in shock tube pyrolysis.
Cathodic Cleavage of Some Aryl Phenacyl Sulfides
Authors: Kunugi Akira , Muto Akinori , Hirai Taketsugu 
Published: July 2006

Abstract
The electrolytic reduction of some aryl phenacyl sulfides in aqueous ethanol and anhydrous acetonitrile solutions has been investigated by means of polarography and controlled potential electrolysis. Dc polarograms of these compounds exhibit two waves in all solutions studied, the first of which corresponds to a one-electron and a two-electron transfer depending upon the absence and presence of proton donor. The electrode reaction taking place at the first reduction step involves cleavage of the carbon–sulfur bond, resulting in formation of acetophenone and the corresponding thiols in good yields even in an acetonitrile solution containing no proton donor. The second reduction step corresponds to the reduction of the acetophenone produced.
Preparation and Structural Studies of Tris[(1R,2R)- or (1R,2S)-2-(Aminomethyl)cyclohexylamine]cobalt(III) Complexes
Authors: Noji Masahide , Toida Haruo , Kidani Yoshinori 
Published: July 2006

Abstract
New cobalt(III) complexes containing (1R,2R)- or (1R,2S)-2-(aminomethyl)cyclohexylamine(=amcha) have been synthesized and separated into diastereoisomers. [Co(1R,2R-amcha)3]3+ gives two diastereoisomers, structures of which were deduced to be mer-Δ and fac-Δ based upon their 13C-NMR and CD spectra. [Co(1R,2S-amcha)3]3+ gives three diastereoisomers, structures of which were determined to be mer-Λ, mer-Δ, and fac-Λ. The conformation of the six-membered chelate rings were investigated in the absence or presence of sulfate ions.
Relative Acidity of Bis(2,4-pentanedionato)(diamine)cobalt(III) Complexes in Lower Dielectric Solvents
Authors: Ito Kazuaki , Iwamoto Etsuro , Hasegawa Kazuko , Yamamoto Manabu , Yamamoto Yuroku 
Published: July 2006

Abstract
The conductances of bis(2,4-pentanedionato)(diamine)cobalt(III) complexes ([Co(acac)2(diamine)]X, diamine: ethylenediamine (en) and N,N′-dimethylethylenediamine (N,N′-dmen), X=Br− and ClO4−) were measured in aprotic solvents covering the approximate range of dielectric constant 5–28 at 25 °C. It was found that a) in spite of the larger size of the methyl derivative the ionic association constants (Ka) for [Co(acac)2(N,N′-dmen)]+ complexes are larger than those for [Co(acac)2(en)]+ complexes in all the composition of nitrobenzene (PhNO2) carbon tetrachloride (CCl4) mixtures (wt % CCl4: 20, 40, 60, 70). b) The reverse trend was obtained in dichloromethane (DCM), 1,1,2,2-tetrachloroethane (1,1,2,2-TCE), and chloroform (CHCl3). These results were explained in terms of hydrogen bonding between the NH protons in the chelate cations and the anions ClO4− and Br−, selective solvation of the NH group side by nitrobenzene, and the desolvation due to the introduction of the N-methyl groups. The relative acidity of NH protons which is controlled by solvation plays an important role in ionic association for the chelate cations with NH protons.
Studies of the Hydrous Tin(IV) Oxide Ion Exchanger. IV. The Effect of Heat Treatment
Authors: Inoue Yasushi , Yamazaki Hiromichi , Nakamizo Hiroshi 
Published: July 2006

Abstract
The effects of heat treatments in air or water at high pressure have been studied regarding the properties of a hydrous tin(IV) oxide ion exchanger. The exchanger in a H+ form was stable against heat treatments in both air and water up to around 80 °C; thereafter the exchange capacity progressively decreased with temperature until 300 °C, at which point it was reduced to about a quarter of the initial value. The exchanger began to crystallize at 300 °C, and formed nearly-complete cassiterite crystals at 500 °C (where the capacity disappeared). In contrast, the exchanger in a Na+ form was more stable against heat treatment than the H+ form; at 400 °C, the Na+ form retained 40 per cent of the initial exchange capacity. An examination of the uptake curves showed that more acidic exchange sites were stronger than less acidic sites against heat treatment. The existence of three kinds of water in the exchanger (adherent, zeolitic, and bound) has been suggested on the basis of the ion-exchange capacity, the thermal-analysis curves, and the recovery of water brought about by humidifying.
Thermodynamic Study for Complexation Reactions of Dibenzo-24-crown-8 with Alkali Metal Ions in Acetonitrile
Authors: Takeda Yasuyuki , Kud\={o} Yasuki , Fujiwara Shizuo 
Published: July 2006

Abstract
Formation constants for 1:1 complexes of dibenzo-24-crown-8 with alkali metal ions in acetonitrile have been determined by conductometry at different temperatures. Enthalpy (ΔH°) and entropy changes (ΔS°) were calculated. All the ΔH° and ΔS° values are negative. The −ΔH° and −ΔS° sequences are Na+&gt;Cs+&gt;Rb+&gt;K+ and Na+≥Cs+&gt;Rb+&gt;K+, respectively.
The Crystal Structure of the β-Form of α-Monolaurin
Authors: Goto Midori , Takiguchi Toshimichi 
Published: July 2006

Abstract
The crystal structure of the β form of α-monolaurin has been determined. The space group is P21, with a=9.2472(3), b=74.310(2), c=4.9523(1)Å, β=97.514(3)°, and Z=8. Two types of molecular conformations of monolaurin exist in the crystal.
Mössbauer Emission Spectra of 119mSn in Tin Organosol
Authors: Ichiba Sumio , Sakamoto Toshio 
Published: July 2006

Abstract
The electron-scavenging effects of adding various solutes to a suspension of tin in ethanol were studied by Mössbauer emission spectroscopy. The yield of the aliovalent species of Sn4+ as the after-effects of the converted isomeric transition in 119mSn varied from the value of the suspension of tin in ethanol, depending on the properties of electron trapping of the solute added.
Synthesis and Swelling Properties of Fluorine Micas with Variable Layer Charges
Authors: Kitajima Kunio , Koyama Fumihiko , Takusagawa Nobuo 
Published: July 2006

Abstract
A series of tetrasilicic Na-micas with variable layer charges (x) between x=1 and x=0.32, NaxMg3−xLix(Si4O10)F2, was synthesized. The expansibility of the synthesized Na-micas upon swelling increased with decreasing layer charge.
Synthesis of Cylindrical Large Ring Crown Hosts
Authors: Kobiro Kazuya , Ohnishi Katsuhiro , Kakiuchi Kiyomi , Tobe Yoshito , Odaira Yoshinobu 
Published: July 2006

Abstract
New cylindrical crown hosts, tridecalino-27-crown-9, tridecalino-21-crown-7, didecalino-cyclohexano-21-crown-7, and didecalinio-21-crown-7 have been synthesized.
Catalytic Debromination of Vicinal Dibromides via Phase Transfer of Diaryltellurium Compounds
Authors: Suzuki Hitomi , Kondo Akiko , Osuka Atsuhiro 
Published: July 2006

Abstract
Several vicinal dibromides were debrominated to olefins by potassium disulfite in the presence of catalytic amounts of bis(4-methoxyphenyl) telluride in a two-phase system.
The Solid State Photochemistry of 2(1H)-Pyrazinones. Structural Revision of the Photoproduct
Authors: Nishio Takehiko , Nakajima Naoko , Kondo Masaji , Omote Yoshimori 
Published: July 2006

Abstract
Irradiation of 1-methyl-5,6-diphenyl-2(1H)-pyrazinone (1a) and 1-methyl-5,6,7,8-tetrahydro-2(1H)-quinoxalinone (1b) in the solid state gave the [4+4] syn-trans cyclodimers (4a–b) in almost quantitative yields, while these pyrazinones in solution phase were inert upon irradiation. On the other hand, the 2(1H)-pyrazinones (1c–e) were inert to photolysis in both the solution and solid states.
Pressure-induced Proton NMR Chemical Shift of Some Simple Hydrocarbon Molecules in Hexane Solution. Marked Low Field Shift of Ethynyl Proton Resonance
Authors: Yamada Hiroaki , Onishi Shuji , Yokoyama Masako , Sera Akira 
Published: July 2006

Abstract
Pressure dependence of the ethynyl proton chemical shift of phenylacetylene was studied in comparison with some simple hydrocarbons. The pronounced low field displacement is interpreted taking account of a geometric feature of the ethynyl group, where the terminal hydrogen atom is exposed to a closer contact with solvent molecules.
Pressure Dependence of l-Leucine-p-nitroanilide Hydrolysis by Leucine Aminopeptidase
Authors: Fukuda Mitsuhiro , Shima Hiroshi , Kunugi Shigeru 
Published: July 2006

Abstract
The effect of pressure on the hydrolysis of l-leucine-p-nitroanilide catalyzed by leucine aminopeptidase from pig kidney was investigated. The activation volumes for kcat process were −8 cm3/mol and −9 cm3/mol for the native enzyme and the modulated one by Mg2+, respectively. The volume changes for the Km process were \simeq0 cm3/mol for both enzymes.
Reverse Osmosis Separations of Aqueous NaCl–Organic Solute Systems
Authors: Kiso Yoshiaki , Kitao Takane 
Published: July 2006

Abstract
Some of alcohols, amides, aromatic hydrocarbons and surfactants were used as organic solute. Addition of NaCl increased the rejections of aromatic hydrocarbons and decreased the rejections of amides. It was also found that the permeability of NaCl was influenced by organic solutes.
Infrared Multiphoton Decomposition of 1-Chloro-1-fluoroethene
Authors: Ogura Hiroo 
Published: July 2006

Abstract
Unimolecular dissociation and subsequent reactions of CH2=CFCl subjected to the infrared multiphoton excitation were studied with a focused geometry using the P(10) line of the 10.6 μm CO2 band at 952.9 cm−1. The final products of the photolysis observed were CH≡CCl, CH≡CF, CH≡CH, CH2≡CHF, and CH2=CF2. A series of diagnostic experiments shows that the primary processes of photolysis involve the molecular elimination of HF and HCl, to minor extent C–Cl bond rupture. The relative importance of the primary steps is tentatively estimated to be approximately 100:65:25, respectively. Primarily formed CH≡CCl and CH≡CF suffer from secondary photolysis, absorbing additional photons. More fraction of CH≡CF primary yield is decomposed than that of CH≡CCl, due to the accidental resonance with the laser excitation line. CH≡CH and CH2=CHF are concluded to be formed by the H atom abstraction reactions of CH≡C· and CH2=CF· radicals generated during the photolysis, respectively, CH2=CF2 being formed by the recombination reaction between CH2=CF· radical and F atom. In the shock tube pyrolysis the formation of CH≡CF predominates over that of CH≡CCl. A mechanistic change to form CH≡CF in the shock tube pyrolysis is suggested.
Vibrational Spectra of β-Lactams. I. 2-Azetidinone and Its Isotopic Compounds
Authors: Hanai Kazuhiko , Maki Yoshifumi , Kuwae Akio 
Published: July 2006

Abstract
The infrared and Raman spectra of 2-azetidinone and its 1-d, 3,3-d2, and 1,3,3-d3 and their 15N compounds have been recorded, and the observed bands have been assigned on the basis of the isotope effects and the normal coordinate analysis. The refined force constants have reproduced the observed frequencies satisfactorily. The C–N stretching mode is strongly coupled with the N–H bending vibration to give a band near 1380 cm−1. However, this coupling does not give rise to any bands corresponding to the amide II and III bands. The concentration dependence of the infrared spectrum suggests the presence of an equilibrium of monomer \leftrightharpoons cyclic dimer in carbon tetrachloride solution. The solvent effects on the N–H and C=O stretching bands have also been examined.
A Novel Iterative Transfer Perturbation Method and Its Application to the Extended Hückel Method
Authors: Imamura Akira , Aoki Yuriko 
Published: July 2006

Abstract
An efficient iterative transfer perturbation method, which enabled us to take into account the contribution of the high order terms in the perturbation series without directly deriving the formulas for terms above third order, is proposed. Consequently we can calculate an infinite series of higher order terms in the perturbation expansion by applying this method iteratively until convergence in the expansion is obtained. By applying this method to methanol, the validity and applicability of our theory are shown at the level of the extended Hückel method.
Kinetics of the Ligand-exchange Reactions in Th(tta)4 and Th(tta)4dmso in Organic Solvents
Authors: Fujiwara Naoshi , Tomiyasu Hiroshi , Fukutomi Hiroshi 
Published: July 2006

Abstract
The exchange reactions of 2-thenoyltrifluoroacetonate (tta) in Th(tta)4 and of dimethyl sulfoxide (dmso) in Th(tta)4dmso have been studied by the NMR method. It was found that the first-order rate constant of tta exchange in acetonitrile-d3 depended linearly on the concentrations of Htta in the enol form, Httaenol, and that the rate was retarded markedly by the addition of DMSO. The activation parameters ΔH\eweq (kJ mol−1) and ΔS\eweq (JK−1 mol−1) were determined to be 43.9±0.5 and −58.4±1.5, respectively and the mechanism including the formation of a nine-coordinate intermediate was proposed. For Th(tta)4dmso, the rate of dmso exchange in acetone-d6 was much faster than that of β-diketonate exchange, and an interchange mechanism was proposed on the basis of a nonlinear dependency of the first-order rate constant on the free DMSO concentration.
New Type of Aldol Condensations Catalyzed by Metal(II) Complexes of α-Amino Acid Esters and that with Cyclodextrin System
Authors: Watanabe Ken-ichi , Yamada Yoichi , Goto Katsuhisa 
Published: July 2006

Abstract
The aldol condensations of p-nitrobenzaldehyde with acetone catalyzed by metal complexes of α-amino acid esters proceeded under mild and neutral conditions to afford an enantiomeric excess aldol-type product, 4-hydroxy-4-(4-nitrophenyl)-2-butanone, along with some dehydrated products without any by-product. The most effective catalyst system was a zinc(II) complex of the tyrosine ethyl ester, ZnII–(TyrOEt)2 in MeOH. Complexes of the second-row transition metals were inadequate for the reactions. Reactions at 30–40 °C for 24 h were favorable regarding the asymmetric induction. An H2O solvent was the best for aldol-type product formations without asymmetric induction. An assistant effect of cyclodextrins(especially, β-CD) on the catalysis of the ZnII–TyrOEt complex were thought to be observed.