bluuebunny/crossref_metadata_2025 huggingface dataset:
Stereochemical Control in Microbial Reduction. 9. Diastereoselective Reduction of 2-Alkyl-3-oxobutanoate with Bakers’ Yeast
Authors: Nakamura Kaoru , Miyai Takehiko , Nagar Ashish , Oka Shinzaburo , Ohno Atsuyoshi
Published: July 2006

Bakers’ yeast reduces esters of 2-alkyl-3-oxobutanoic acid (CH3COCHRCO2R′; R=methyl, ethyl, propyl, propargyl, and allyl) into the corresponding (S)-hydroxy esters with exclusive stereoselectivity, while the configuration at the 2-position of the hydroxy esters is either S (anti) or R (syn) depending on the structure of the alkoxyl group in the carboalkoxyl moiety of the ester. Oftenly, the stereoselectivity with respect to the 2-position is not satisfactory. In general, the reduction of t-butyl esters exerts predominancy in the products, whereas that of 1,1-dimethylpropyl esters exerts the syn predominancy. A marked difference between these two esters in diastereoselectivity is discussed from the view point of plausible conformations of the esters.
A Study of Dielectric Solvent Effect on Silicon-29 NMR Chemical Shifts of Some Chlorosilanes
Authors: Takayama Toshio , Ando Isao , Asakura Tetsuo
Published: July 2006

The dielectric solvent effect on the 29Si NMR chemical shifts of some chlorosilanes is calculated by means of the finite perturbation theory within the CNDO/2 framework using the solvaton theory which is employed to estimate specific solute-solvent bonded interactions as a function of the dielectric constant of the medium. The calculated variations are reasonably compared with the gross trend of the observed solvent effects of 29Si chemical shifts. Further, the origin of the dielectric solvent effect is discussed.
Nonequilibrium Thermodynamic Studies on Membrane Phenomena. Transport of Electrolytic Solutions through Progesterone Plug Membrane
Authors: Srivastava M L , Ram Bali
Published: July 2006

Studies on hydrodynamic and electroosmotic permeation of water and aqueous solutions of NaCl, KCl, and MgCl2 across progesterone plug membrane have been carried out to characterize the electrical nature of progesterone interfaces. Electrophoretic mobilities of progesterone particles dispersed in these aqueous solutions have also been measured. Experiments were confined to the range where linear flux/force relationships hold. Membrane parameters have been evaluated with the data obtained and the membrane/solution electrical interface has been explained using electrical double layer model and theory of nonequilibrium thermodynamics. Zeta potentials have been evaluated from electroosmotic and electrophoretic flux data and their dependence on concentration examined.
Carbohydrate Complexes with Lead(II) Ion. Interaction of Pb(II) with β-d-Glucurono-6,3-lactone, d-Glucono-1,5-lactone, and Their Acid Anions and the Effects of Metal Ion Binding on the Sugar Hydrolysis
Authors: Tajmir-Riahi Heidar-Ali
Published: July 2006

The interaction of Pb(II) ion with β-d-glucurono-6,3-lactone, d-glucuronic acid, d-glucono-1,5-lactone, and their acid anions has been investigated in aqueous solution and solid compounds of the type Pb(d-glucurono-6,3-lactone)(NO3)2, Pb(d-glucuronic acid)(NO3)2, Pb(II)–d-glucuronate, Pb(d-glucono-1,5-lactone)(NO3)2, and Pb(II)–d-gluconate have been isolated. These compounds are characterized by means of FT-IR, 1H and 13C NMR spectroscopy and molar conductivity measurements. Among these Pb–sugar complexes, the crystal structure of the Pb(II)–d-gluconate is known through X-ray diffraction measurements, in which the lead(II) ion is hexa-coordinated, binding to four d-gluconate anions via a carboxylato oxygen and an α-hydroxyl group of the two anions (chelation) and to a carboxylato oxygen atom of the other two sugar anions (unidentately). Spectroscopic evidence suggested that in the Pb–lactone or Pb–acid adducts, the metal ion could be bonded to a lactone or acid molecule through one of the carbonyl oxygen atom and other sugar donor group as well as to two bridging nitrato groups. In the Pb(II)–d-glucuronate, the metal ion could be bonded to four sugar moieties (similar to that of the Pb(II)–d-gluconate) via a carboxylato oxygen atom and other sugar donor group of the two anions and to a carboxylato oxygen atom of the other two acid anions, resulting into a hexa-coordinated lead(II) ion. The β-anomer sugar configuration is predominant in the free d-glucurono-6,3-lactone, d-glucuronic acid, d-glucuronate anion and in these Pb–sugar complexes.
A Time-Resolved CIDEP Study of the Laser Photoreduction of Pyruvic Acid by Lactic Acid
Authors: Craw Marjory T , Depew M Catherine , Adrian Frank J , Wan Jeffrey K S
Published: July 2006

In addition to the well-known initial phototriplet polarization, unusual Chemically Induced Dynamic Electron Polarization (CIDEP) behavior in solutions of neat pyruvic acid/lactic acid has been attributed to ST_ Radical Pair Mechanism (RPM) polarization in combination with absorptive initial Triplet Mechamism (TM) polarization and ST0 RPM polarization. Significant ST_ RPM contributions to such carbon centered radicals with small hyperfine splittings have rarely been observer in solution at room temperature.
Natural 2,6-Dialkyl-3-piperidinols. 9. Total Synthesis of (±)-Prosafrinine and 13C NMR Studies of Some Analogous Compounds
Authors: Paterne Michel , Dhal Robert , Brown Eric
Published: July 2006

1,7-Dibromoheptane was used to alkylate both ketoesters 2 and 4 successively. Hydrolysis and decarboxylation of the resulting intermediate afforded the ethylenic diketone (6). Ozonolysis of the double bond of 6 gave the diketonic aldehyde (8). Alkaline condensation of nitroethane on the aldehydic carbonyl of the latter, followed by hydrogenation using a Pd–Pt catalyst, afforded 3-r-hydroxy-6-c-(10-oxododecyl)-2-c-methylpiperidine [(±)-prosafrinine] (1a) and (±)-3-epiprosafrinine (1b). The structures of 1a, 1b, and some analogues were confirmed by 13C NMR studies.
The Photochemistry of Steroidal 6-Membered Cyclic α-Nitro Enones
Authors: Suginome Hiroshi , Kurokawa Yoshitaka
Published: July 2006

The products of the photolysis of two steroidal cyclic α-nitro enones, newly synthesized, were compared with those of the cyclic α-nitro ketones and cyclic enones. Direct irradiation of 2α-nitrocholest-4-en-3-one in protic solvents resulted in an unexpected α-cleavage of the carbonyl group and gave 3-alkoxy-2-nitro-2,3-secocholest-4-en-3-one while irradiation of 4α-nitro-5α-cholest-1-en-3-one gave the parent cholest-1-en-3-one which arose from the removal of the nitro group.
Studies of Liquid Water by Computer Simulations. VI. Transport Properties of Carravetta–Clementi Water
Authors: Kataoka Yosuke
Published: July 2006

The micro canonical molecular dynamics simulations of liquid water were performed at different temperatures and densities in order to investigate the anomalies of the transport coefficients. The nonempirical Carravetta–Clementi potential was used for the system with 216 molecules in a cubic cell. The order of magnitude of the nonempirically calculated self-diffusion coefficient, shear viscosity, bulk viscosity, and thermal conductivity were in agreement with experimental results. These transport properties were recognized as anomalous as in real liquid water. The temperature-dependence of these quantities was in agreement with the observed values under pressure of 50 MPa. The effects of compression on these transport coefficients were reproduced qualitatively. The obtained bulk viscosity was larger than the shear viscosity at low temperatures in accordance with experiments. The contribution of rotational motion to thermal conductivity seems to be responsible for the anomalous temperature-dependence of thermal conductivity. Several decay constants of the time correlation functions were obtained. The frequency spectra of the correlation functions were discussed. No marked molecule number dependence was observed in the calculated transport coefficients of Matsuoka–Clementi–Yoshimine water.
Adsorption of 2-(Octylsulfinyl)ethanol at Ethanol–Water Mixture/Air Interface
Authors: Iyota Hidemi , Motomura Kinsi
Published: July 2006

The surface tension of the solution of 2-(Octylsulfinyl)ethanol (OSE) in ethanol–water mixture was measured as a function of molality of OSE at constant composition of ethanol at 298.15 K under atmospheric pressure. The slope of surface tension vs. molality curve decreased with increasing composition. Two break points were observed on the curve: the break point at a low molality was attributed to the phase transition of the adsorbed film of OSE and the one at a high molality to the micelle formation of OSE. The surface excess numbers of moles per unit area of OSE and ethanol and their ratio were evaluated by applying the thermodynamic equations developed previously to the experimental results. It was clarified that the adsorbed film of OSE expels ethanol molecules from the surface region at a small composition of ethanol. The ratio of the excess number of molecules of ethanol per micelle particle to that of OSE was found to be similar to the corresponding ratio of the surface excess number of moles at the critical micelle concentration. This fact led us to the conclusion that the OSE molecules in the micelle behave similarly to those in the adsorbed film even in the mixed solvent.
Solvent Extraction of Various Metal Picrates with Benzo-18-crown-6 into CHCl3
Authors: Takeda Yasuyuki , Nishida Minoru
Published: July 2006

Overall extraction equilibrium constants (Kex) of various metal picrates (MAm) with benzo-18-crown-6 (B18C6) and distribution constant (KD,L) of B18C6 were determined at 25 °C between water and chloroform. The Kex values were analyzed by constituent equilibria, e.g., KD,L, formation constant in water and ion-pair extraction constant (Kex,ip) with a picrate anion of the B18C6–metal ion complex. Kex orders for univalent and bivalent metal ions are Tl+>K+>Rb+>Ag+>Cs+>Na+ and Pb2+>>Sr2+>Ca2+, respectively. Extraction selectivities of B18C6 for the alkali and alkaline earth metal ions are consistent with the size-fit concept; namely, the more closely a cation fits into a crown ether cavity, the more extractable the complex is. For a given B18C6–Mm+ system, Kex,ip value is much larger than values of the other constituent equilibria. Thus, the magnitude of Kex value is determined largely by that of Kex,ip value. Kex,ip value of B18C6 for univalent and bivalent metal ions increases in the order Na+<Ag+<Cs+<K+<Rb+<Tl+ and Sr2+<Ca2+<Pb2+, respectively. Factors governing the magnitude of the Kex,ip value were discussed in detail.
The Spectrophotometric Determination of Phosphate Following the Collection of Ion Pair of Molybdophosphate with Bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) on an Organic Solvent-Soluble Membrane Filter
Authors: Taga Mitsuhiko , Kan Masahiko
Published: July 2006

A rapid and sensitive method of determining phosphate was described. The ion pair of molybdophosphate with bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) (Co-5-Cl-PADAP) formed in 0.075 mol dm−3 sulfuric acid, 0.225 mmol dm−3 ammonium molybdate, and 25 μmol dm−3 Co-5-Cl-PADAP was collected on an organic solvent-soluble membrane filter made of cellulose nitrate. The membrane filter with the ion pair was then dissolved into N,N-dimethylformamide, and the absorbance of the solution was measured for the determination of phosphate. The calibration curve was linear up to 0.4 μg as phosphorus, with the correlation coefficient of 0.999, and the apparent molar absorption coefficient of phosphate was 2.9×105 dm3 mol−1 cm−1. The relative standard deviation was 1.7% for 0.4 μg of phosphorus. Although dodecyl sulfate existing in an amount ten times that of phosphorus caused a positive error, no ions commonly existing in natural waters interfere with the determination of phosphate. The proposed method was applied to the determination of μg dm−3 levels of phosphate-phosphorus in natural waters, and satisfactory results were obtained.
Novel Synthesis of Carbamate Ester from Carbon Dioxide, Amines, and Alkyl Halides
Authors: Yoshida Yasuhiko , Ishii Shigeru , Watanabe Masayo , Yamashita Tadataka
Published: July 2006

A novel synthesis of carbamate ester using carbon dioxide as a direct material is reported in this article. The direct reaction of carbon dioxide, aliphatic amines, and alkyl halides was found to give the corresponding alkyl carbamate esters in good yields. Reactions using secondary alkyl bromides gave carbamate esters in higher yields than those using primary or tertiary alkyl bromides. The carbamate ester yields increased with the addition of N,N-dimethylformamide to the reaction system of carbon dioxide, amines and, alkyl halides. This reaction is considered to proceed by an SN2 displacement reaction of the alkyl halide by the carbamate anion formed from the reaction of carbon dioxide and the amine.
Novel Electron Acceptors Bearing a Heteroquinonoid System. II. Synthesis and Conductive Complexes of 2,5-Bis(dicyanomethylene)-2,5-dihydrothieno[3,2-b]thiophene, 2,6-Bis(dicyanomethylene)-2,6-dihydrodithieno[3,2-b:2′,3′-d]thiophene, and Their Derivatives
Authors: Yui Koji , Ishida Hideki , Aso Yoshio , Otsubo Tetsuo , Ogura Fumio , Kawamoto Atsushi , Tanaka Jiro
Published: July 2006

Novel heteroquinonoid compounds as potential electron acceptors, 2,5-bis(dicyanomethylene)-2,5-dihydrothieno[3,2-b]thiophene (4a), 3,6-dibromo derivative, 2,6-bis(dicyanomethylene)-2,6-dihydrodithieno[3,2-b:2′,3′-d]thiophene, 3,5-dibromo derivative, and 4,4-dioxide were synthesized by the action of tetracyanoethylene oxide or by a Pd(0)-catalyzed substitution reaction with sodium dicyanomethanide on the corresponding α,α′-dihalo-substituted fused thiophenes. They show effectively diminished on-site Coulomb repulsion owing to the extensive conjugation, and most of their molecular complexes with various electron donors exhibit very high electrical conductivities up to metallic region. In addition, X-ray crystallographic analysis of the complex of 4a with bis(ethylenedithio)tetrathiafulvalene has elucidated that sulfur atoms embedded in 4a molecule are capable of inducing a significant intermolecular interaction, forming a sheet-like network structure.
Oxetane Derivatives and Their Polymers for Designing Functional Polymers Containing a Soft, Somewhat Polar Polyether Network as a Polymer Support
Authors: Motoi Masatoshi , Nagahara Shinsuke , Yokoyama Mitsuru , Saito Eiichi , Nishimura Osamu , Kanoh Shigeyoshi , Suda Hiroshi
Published: July 2006

Several oxetane derivatives having functional groups, such as ester, ketone, ether, acetal, and azo, at the end of 2-oxapolymethylene spacers which were linked to the C-3 carbon of an oxetane ring were readily prepared by a substitution reaction of the corresponding bromide of the oxetane. These oxetanes were polymerized by cationic ring-opening polymerization to give their polymers with molecular weights ranging from 16000 to 1000, depending on the structure of the functional group of the monomer used. When using bisoxetanes as a cross-linking agent in the above polymerization, insoluble resins containing soft, somewhat polar polyether networks as a polymer support were obtained. Some chemical reactions of the pendant functional groups were also examined for the oxetane derivatives and their polymers.
Aryliminodimagnesium Reagents. XVI. Formation of o-Hydroxyazoarenes by Condensation with o-Hydroxynitroarenes. Favorable Role of o-Hydroxyl Group in the Reaction
Authors: Okubo Masao , Nakashima Takanori , Shiku Haruko
Published: July 2006

Hydroxy(HO)-azoxy- and -azoarenes were formed by condensation of ArN(MgBr)2 with o-, m-, and p-HO-nitrobenzenes; nuclear substitution took place as a minor or a major pathway. o-HO-azobenzene was obtained in sufficiently high yield. Relative yields of the products varied according to the position of HO group and reaction conditions. The yield variation was explained by the effects of relative efficiency of single electron transfer, σ-complexation, and cooperation of reagent molecules.
Solubilization of β-Carotene in Water by Water-Soluble Linear Macromolecules
Authors: Inamura Isamu , Isshiki Masayuki , Araki Takeo
Published: July 2006

β-Carotene was solubilized in water by the water-soluble linear macromolecules of poly(N-vinylpyrrolidone) (PVP), polyethylene glycol (PEG), poly(vinyl alcohol) (PVA), and dextran. Absorption of β-carotene in aqueous macromolecular solutions were red-shifted. The rate of photobleaching of β-carotene in water depended on the polymer species.
Synthesis and Molecular Structure of Hexacarbonyl(tropone)diiron
Authors: Morita Noboru , Kabuto Chizuko , Asao Toyonobu
Published: July 2006

Molecular structure of hexacarbonyl(tropone)diiron has been investigated by X-ray diffraction studies.
Selective Reduction of α,β-Unsaturated Carbonyl Compounds with Carbon Monoxide and Water Assisted by Selenium
Authors: Nishiyama Yutaka , Makino Yasuhiko , Hamanaka Sawako , Ogawa Akiya , Sonoda Noboru
Published: July 2006

Carbon–carbon double bond of α,β-unsaturated carbonyl compounds can be reduced selectively with hydrogen selenide, generated in situ by the reaction of elemental selenium with carbon monoxide and water in the presence of strongly basic tertiary amine.
Novel Ferroelectric Liquid Crystals Derived from n-Alkyl Esters of (R)-3-Hydroxybutanoic Acid (II), the Correlation between Their Ferroelectric Properties and Their Molecular Structure
Authors: Nakauchi Jun , Kageyama Yoshitaka , Hayashi Seiji , Sakashita Keiichi
Published: July 2006

The temperature dependence of the spontaneous polarization (Ps) and the optical tilt angle (θ) of the following series of novel ferroelectric liquid crystals, derived from normal alkyl esters of (R)-3-hydroxybutanoic acid, have been investigated.

(Remark: Graphics omitted.)

The magnitude of Ps and θ depends on the kind of linkage groups and their position in the core moiety as well as on the lengths of both terminal chains. The Ps’s for I(m,n) and II(m,n) show a maximum at (m,n)=(10, 3), whereas their θ’s increase with the m and do not change very much with n. In comparison with four analogues (I(10,3), II(10,3), III(10,3), and IV(10,3)), which have the same terminal chains, but which show a different phase sequence, the magnitudes of Ps and θ are in the orders of: III(10,3)>IV(10,3)>I(10,3)∼II(10,3) and III(10,3)>I(10,3)>II(10,3)>IV(10,3) respectively. Among all the compounds, the III(10,3) shows the maximum Ps as high as 1100 μCm−2 in the chiral smectic C phase and as high as 1750 μCm−2 in the chiral smectic I phase.
Direct Determination of Hyperfine Coupling Constants from Complex and Poorly Resolved ESR Spectra with Numerical Decoupling Analysis
Authors: Nozaki Koichi , Naito Akira , Hatano Hiroyuki , Okazaki Satoshi
Published: July 2006

Numerical decoupling analysis (NDA) has been developed as a useful analytical method for determining accurate hyperfine coupling constants (hfccs) involved in isotropic ESR spectra with constant line-widths. NDA was found to have a number of advantages over other methods developed for the extraction of hfccs from ESR spectra. For example, the nuclear spin (e.g., I=1⁄2 or 1) can easily be distinguished and hfccs as small as a linewidth can be determined. Furthermore, false hfccs which often appear and lead to confusion in obtaining the true values in other methods are largely eliminated. Owing to these advantages NDA has enabled us to interpret not only complex but also poorly resolved ESR spectra. The practical use of NDA could be demonstrated by analyzing the ESR spectra of t-butyl 4-nitrophenyl nitroxide and t-butyl 2-chlorophenyl nitroxide radicals.
Syntheses, and Crystal and Molecular Structures of Tetramethylammonium[Aquamethanolhexakis(isothiocyanato)lanthanoidates(III)], [(CH3)4N]3[M(NCS)6(CH3OH)(H2O)] (M=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er), and Tetramethylammonium [Heptakis(isothiocyanato)lanthanoidates(III)], [(CH3)4N]4[M(NCS)7](M=Dy, Er, Yb)
Authors: Matsumoto Fumiko , Matsumura Naomi , Ouchi Akira
Published: July 2006

The title complexes were synthesized and their crystal and molecular structures were determined by the X-ray diffraction method using their single crystals. The crystals of the former ten hexakis(isothiocyanato) complexes of lanthanum through dysprosium(III) and erbiun(III) are isomorphous with each other: monoclinic, space group P21, Z=2. The central metal atom is octa-coordinated, in a square-antiprism geometry, to six nitrogen atoms of thiocyanato (SCN) ions and two oxygen atoms of methanol and water molecules. The two oxygen atoms take the positions of the most approaching apexes of two squares. The latter three heptakis(isothiocyanato) complexes of dysprosium, erbium, and ytterbium are in another isomorphous form with each other: orthorhombic, space group P21nb, Z=4. The central metal atom is hepta-coordinated, in a deformed pentagonal-bipyramidal geometry, to seven nitrogen atoms of SCN ions.
Stopped-Flow Kinetics of the Formation and Decomposition of 2,4- and 4,4-Disubstituted Meisenheimer Complexes in the Reaction of 4-Piperidino-1,3-dinitrophenanthrene with Potassium Methoxide in Dimethyl Sulfoxide–Methanol
Authors: Takahashi Hiroyuki , Hiraide Takao , Hashida Yohji , Sekiguchi Shizen
Published: July 2006

The formation of 2,4-disubstituted anionic σ complex, followed by the formation of 4,4-disubstituted one was confirmed by means of absorption and NMR spectra in the reaction of 4-piperidino-1,3-dinitrophenanthrene with potassium methoxide in DMSO–CH3OH. The rates and activation parameters were determined by kinetic studies using stopped-flow and conventional spectrophotometers. It was found, compared with the previous results on the naphthalene system that the presence of H5 of the title compound affects the rates differently.
Variable-Temperature and Variable-Pressure Nitrogen-14 NMR Studies on the Exchange Reaction of Different Nitriles at the Nickel(II) Ion
Authors: Ishii Masao , Funahashi Shigenobu , Ishihara Koji , Tanaka Motoharu
Published: July 2006

The activation parameters for the exchange reaction of several nitriles at the nickel(II) ion have been determined for the nickel(II) trifluoromethanesulfonate solutions by means of the 14N NMR line broadening method at various temperatures and pressures up to 220 MPa. Values of activation enthalpy (ΔH\eweq/kJ mol−1), activation entropy (ΔS\eweq/J mol−1 K−1), and activation volume at zero pressure (ΔV0\eweq/cm3 mol−1) for the exchange of various nitriles are respectively as follows: 41.4±0.5, −30±2, and +12.0±0.4 in acetonitrile; 42.0±0.4, −25±2, and +13.7±0.5 in propionitrile; 43.3±0.7, −23±2, and +13.1±0.5 in butyronitrile; 43.3±0.5, −19±2, and +12.4±0.6 in isobutyronitrile; 47.1±1.2, −10±4, and +14.4±0.4 in valeronitrile; 51.6±1.9, +4±6, and +13.1±0.6 in benzonitrile. The activation volume varies little in spite of the large variation of the molar volume of nitriles. The activation energy (EQ/kJ mol−1) and the activation volume at zero pressure (ΔVq\eweq cm3 mol−1) for the reorientation of nitrile molecules around the axis perpendicular to the C≡N bond were also determined to be respectively as follows: 7.4±0.1 and +8.3±0.4 for acetonitrile; 8.1±0.1 and +9.5±0.2 for propionitrile; 9.2±0.1 and +9.7±0.3 for butyronitrile; 9.1±0.1 and +11.3±0.2 for isobutyronitrile; 10.7±0.2 and +11.9±0.2 for valeronitrile; 12.5±0.2, and +13.5±0.2 for benzonitrile. Both EQ and ΔVq\eweq increase with increasing bulkiness of the substituent to the cyano group.
Thermal Ring-Splitting Reactions of Diarylcyclobutanes: Significance of Steric Effects on Orbital Interactions in Transition States and Biradical Intermediates
Authors: Yasuda Masahide , Yoshida Kouhei , Shima Kensuke , Pac Chyongjin , Yanagida Shozo
Published: July 2006

Regiochemistry and reactivities in the thermal ring-splitting reactions of diarylcyclobutanes (1–5) have been studied and shown to depend on the stable conformations and rotational mobilities of the aryl substituents. The reactions of 1 and 2 result in a regiospecific symmetric cleavage to give indene or styrene along with significant isomerization of 2 to 3. In the cases of 3–5 both the symmetric and unsymmetric cleavages competitively occur with decreasing symmetric-to-unsymmetric ratios with an increase in methyl substitution. The olefin products from 4 are mixtures of cis- and trans-2-butene, cis- and trans-β-methylstyrene, and trans-stilbene. Thermochemical analyses combined with product analyses indicate that the symmetric cleavage of 1 and the unsymmetric cleavage of 3 proceed with a concerted mechanism, whereas 1,4-biradicals are involved in the other reactions. Structure-reactivity relationships of the present reactions are discussed in terms of mixing of the σ* character in a bonding MO by specific π–σ* interactions, depending on the conformational situations of the aryl groups and in terms of the steric effects which destabilize 1,4-biradicals as well as transition states of the biradical fragmentation to the olefins.
Stopped-Flow Kinetics of Reactions of 1-Ethoxy-2,4-dinitronaphthalene with Pyrrolidine and Piperidine in Dimethyl Sulfoxide Solution
Authors: Fujinuma Hajime , Hosokawa Masaru , Suzuki Tohru , Sato Mitsuo , Sekiguchi Shizen
Published: July 2006

The reaction of 1-ethoxy-2,4-dinitronaphthalene (1) with pyrrolidine or piperidine in dimethyl sulfoxide occured in two stages (Stages I and II). In the stage I, a σ-adduct forms at such a rate as is measured by a stopped-flow technique, and in the stage II it decays at a slower and spectrophotometrically measurable rate. The pyrrolidine system is more reactive than the piperidine system in the stages I and II, with the former reactivity in the stage II being ca. 11000 times higher than the latter. This huge difference was found by NMR evidence to stem from the structure of transition state in the stage II. Further, the activation parameters were determined, which corresponded to such difference in reactivity very well.
The Crystal and Molecular Structure of Di-μ-hydroxo-bis[pentaaquascandium(III)] Benzenesulfonate Tetrahydrate, [{(H2O)5Sc}(OH)2{Sc(H2O)5}](C6H5SO3)4·4H2O: A Dimeric Complex in Pentagonal-Bipyramidal Hepta-Coordination
Authors: Matsumoto Fumiko , Ohki Yoshiyuki , Suzuki Yasuo , Ouchi Akira
Published: July 2006

The crystal and molecular structure of the mew title complex has been determined by means of a single crystal X-ray diffraction method. It is triclinic with the space group P\bar1, Z=2, a=15.518(5), b=19.827(7), c=7.493(2) Å, α=100.90(3), β=103.94(2), γ=82.85(3)°. Both of the metal atoms have almost the same coordination geometry, pentagonal bipyramidal which coordinates the oxygen atoms of five water molecules (2 axial and 3 equatorial ones) and the two hydroxide ions which bridge the both metal atoms. The Sc(1)···Sc(2) distance is 3.403(2) Å. The average Sc–O(H2O) bond length is 2.194 Å, which is much longer than that of Sc–O(OH), 2.072 Å. Benzenesulfonate ions and the other water molecules do not coordinate to the metal atoms, though their oxygen atoms as well as those of the coordinated water are connected with each other by a network involving hydrogen bonding.
Syntheses of 1β-Hydroxyvitamin D2 and D3
Authors: Tachibana Yoji
Published: July 2006

Reduction of 1-oxo-3,5-cyclovitamin D2 and D3 was carried out under various conditions. LiAlH4 reduction in ether preferentially afforded 1β-hydroxy-3,5-cyclovitamin D2 and D3, which were converted to 1β-hydroxyvitamin D2 and D3.
Studies on Aromatic Sesquiterpenes. XI. Synthesis of 7-Isopropyl-3,5-dimethyl-1-naphthol
Authors: Tanaka Juichi , Adachi Kazuo
Published: July 2006

Starting from m-cresol, the title new naphthol was synthesized through 4-methyl-3-(2-methoxy-4-methylbenzoyl)pentanoic acid as a key intermediate.
Stereoselective Synthesis of 3′-Deoxy-3′-fluoroadenosine
Authors: Morizawa Yoshitomi , Nakayama Toshiaki , Yasuda Arata , Uchida Keiichi
Published: July 2006

A new fluorinated nucleoside, 3′-deoxy-3′-fluoroadenosine(1), has been synthesized by a six-step synthesis from methyl 2-O-benzyl-5-O-t-butyldimethylsilyl-β-d-xylofuranoside (2a). Activation of O-3 by formation of a triflate followed by nucleophilic displacement allowed introduction of fluoride ion in a stereospecific manner at C-3.
Photoisomerization of Oxime Ethers and Efficiency of Triplet Formation via Exciplexes
Authors: Takeda Yoshihiko , Misawa Hiroaki , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

9,10-Dicyanoanthracene(DCA)-sensitized isomerization of (E)- and (Z)-isomers of an oxime ether of 2-acetylnaphthalene (E-1 and Z-1, respectively) was investigated in benzene by means of steady irradiation and laser flash photolysis. The excited singlet DCA was effectively quenched by E-1 and Z-1 to afford exciplexes, decay of which gave DCA triplets or 1 triplets. The triplet state of 1 was proposed as the isomerization intermediate and the formation efficiency of 1 triplets was estimated from isomerization quantum yields.
Redox Behavior of Simple Vitamin B12 Model Complexes and Electrochemical Catalysis of Carbon-Skeleton Rearrangements
Authors: Murakami Yukito , Hisaeda Yoshio , Fan Sheng-Di , Matsuda Yoshihisa
Published: July 2006

Various cobalt complexes of 4,10-dipropyl-5,9-diazatrideca-4,9-diene-3,10-dione dioxime, (C2C3)(DOH)2pn, were prepared, and redox behavior of them was investigated by means of cyclic voltammetry; Co(II)/Co(I) redox potentials in the range of −0.69 through −0.7 V vs. Ag/AgCl. The monomethylated complex, which has a cobalt–carbon bond at one axial site of the nuclear cobalt, was disproportionated to the dimethylated complex, involving two cobalt–carbon bonds at both axial sites, and the CoI species by one-electron reduction. The dimethylated complex was inactive for electrochemical reduction, but transformed into the monomethylated complex via cleavage of a cobalt–carbon bond upon electrochemical oxidation. The electrolyses of 1-bromo-2,2-bis(ethoxycarbonyl)propane, 1-bromo-2-cyano-2-ethoxycarbonylpropane, and 2-acetyl-1-bromo-2-ethoxycarbonylpropane in the presence of [CoIII{(C2C3)(DO)(DOH)pn}Br2] in N,N-dimethylformamide did not proceed in a divided cell at −2.0 V vs. Ag/AgCl, since the corresponding dialkylated complexes, inactive for electrochemical reduction, were formed in the course of reaction. When imidazole was added to solutions for the electrolysis, the reaction proceeded efficiently by the trans effect arising from the coordinated axial base and the corresponding carbon-skeleton rearrangement products were obtained. On the other hand, the carbon-skeleton rearrangement proceeded in an undivided cell even in the absence of imidazole; the dialkylated complex was decomposed to give the monoalkylated complex and the reduction and rearrangement products by electrochemical oxidation on the anode.
An Oxygen Exchange of Arsenate and Alkylarsonate Ions with Water
Authors: Niwa Nobuko , Fushimi Midori , Iida Masayasu , Horie Yuko , Yamabe Shinichi , Okumura Akiko
Published: July 2006

The oxygen exchange rates, R′s, between the alkylarsonates (methyl- and butyl-) and water were measured over the pH range greater than 9 and at 30 °C. The rates were analyzed in terms of the rate law, R=k1[R′-AsO3H−]+k2[R′-AsO32−] (R′-; alkyl-) to obtain k1 to be 6.64×10−4 s−1 for methyl- and 4.38×10−4 s−1 for butylarsonate ions, respectively. The first-order oxygen exchange rate constants, k1’s, on the alkylarsonate univalent anions (methyl and butyl) are almost the same values, which indicates that the steric effect on the rate is absent. The rate constants, k1’s, correlate well with energy levels of the lowest unoccupied molecular orbitals (ELUMO’s) of univalent anions of arsenic, arsenious, and alkylarsonic acids.
Pyranyl Radicals and Their Dimers
Authors: Kawata Hiroki , Niizuma Shigeya
Published: July 2006

Photochemical and chemical reduction of pyrylium salts in THF solution gave their corresponding radicals which were in equilibrium with dimers. The quantum yields for raidcal formation and the standard enthalpy change ΔH0 for dimerization decrease with increasing the electron-donating character of the substituting groups in the pyrylium ring. Specially, ΔH0 for pentaphenylpyranyl and pentaphenylthiopyranyl radicals, in which all carbons in the ring are substituted by phenyl groups, become possitive. The absorption maxima and their molar extinction coefficients of pyranyl radicals, and concurrently the equilibrium constants for the dimerization were determined spectrophotometrically.
The Hypervirial Condition in the Hückel Model
Authors: Isihara Makoto
Published: July 2006

This paper analyzes a fundamental aspect of the Hückel model through the hyperviral theorem. The analysis leads to the condition to be satisfied by bond orders and site electron densities as a set of linear equations. The condition, named the hypervirial condition, is common to all the eigenstates of the Hückel model Hamiltonian and brings information on a sort of detailed balance in electron distribution. The hypervirial and the symmetry conditions are related to each other, being consistent but not fully equivalent. Examination of the relation between the two conditions results in the concept of the “intrinsic” hypervirial condition that remains nontrivial with the symmetry condition fulfilled. Several examples provide various expressions obtainable from the hypervirial condition to facilitate understanding the nature of the condition. A few features of the hypervirial condition for alternant systems are mentioned.
Synthesis and Structural Analysis of 4-Deoxy-4-(hydroxyphosphinyl and phenylphosphinyl)-d-ribofuranoses
Authors: Hanaya Tadashi , Yamamoto Hiroshi
Published: July 2006

Methyl 2,3-O-isopropylidene-β-d-ribopyranoside gave efficiently (in 4 steps) methyl 4-deoxy-4-[dimethoxyphosphinyl and (methoxy)phenylphosphinyl]-2,3-O-isopropylidene-β-d-ribopyranosides (ca. 30% overall yield). These were led (in 2–3 steps) to the title compounds and then converted into 1,2,3,5-tetra-O-acetyl-4-deoxy-4-(methoxyphosphinyl and phenylphosphinyl)-d-ribofuranoses, whose structures and 3T2 (and 2T3) conformations were established by spectroscopy.
Solvent Extraction of Thallium(I) Picrate into Benzene with Mixtures of Crown Ethers and Tributyl Phosphate
Authors: Takeda Yasuyuki
Published: July 2006

Thallium(I) picrate was extracted into benzene at 25 °C with crown ether (15-crown-5 (15C5) and benzo-15-crown-5 (B15C5)) and/or tributyl phosphate (TBP). The crown ether complex with thallium picrate (1:1:1) accepts one TBP molecule. The thallium picrate complex with B15C5 and TBP is more stable than the corresponding 15C5 complex in benzene.
Decomposition Reaction of 3-Aryl-6-disubstituted Amino-1,4,2,5-dithiadiazines in the Solid State
Authors: Yonemoto Katsumi , Shibuya Isao
Published: July 2006

3-Diethylamino-6-phenyl-1,4,2,5-dithiadiazine, on standing in air at room temperature, decomposed to afford 5-diethylamino-3-phenyl- and 3,5-bis(diethylamino)-1,2,4-thiadiazoles, whereas in the melt and in solution it was remarkably stable. With increasing bulkiness of substituents (Ar and/or NR2) in 1,4,2,5-dithiadiazines, their stability in the solid state clearly enhanced. Some interstack interactions in the crystal seem to favor the decomposition.
Solubilization of Hemin in Neutral and Acidic Aqueous Solutions by Forming Complexes with Water-Soluble Macromolecules
Authors: Inamura Isamu , Isshiki Masayuki , Araki Takeo
Published: July 2006

Hemin was solubilized in neutral and acidic aqueous solutions by complexing with poly(N-vinylpyrrolidone) (PVP), polyethylene glycol (PEG), poly(vinyl alcohol) (PVA) and dextran. In neutral aqueous solutions, hemin in the PVP, PEG, and PVA complexes was monomeric and that in the dextran complex was dimeric. The effects of pH and ultraviolet (UV) irradiation on the spectroscopic properties of the complexes were examined.
The Crystal and Molecular Structures of Tetraethylammonium [Tetraaquatetrakis(isothiocyanato)neodymate(III) and europate(III)], [(C2H5)4N][M(NCS)4(H2O)4], (M=Nd, Eu)
Authors: Ouchi Akira
Published: July 2006

The crystal and molecular structures of the title new complexes were determined by means of a single-crystal X-ray diffraction method. The crystals of the neodymium(III) complex, NdC12H28N5O4S4, F. W. 578.87, are triclinic, space group P\bar1, a=14.13(2), b=15.39(1), c=12.92(1) Å, α=106.81(8), β=114.70(9), γ=90.09(10)°, U=2418(5) Å3, Z=4, Dm=1.57(3), Dx=1.59 g cm−3, μ(MoKα)=25.22 cm−1. The isomorphous europium(III) complex was also obtained: a=14.069(9), b=15.328(9), c=12.865(9) Å, α=106.98(5), β=114.57(5), γ=90.07(6)°, U=2390(3) Å3, Dm=1.60(3), Dx=1.63 g cm−3, μ(Mo Kα)=30.04 cm−1. Two crystallographically independent neodymium(III) atoms in a unit cell have approximately the same coordination geometry: square antiprism 4O,4N-octa-coodination. A pair of the O atoms as well as N atoms are in cis positions on the top square and in trans positions on the bottom square of each polyhedron, where the lines connecting both pairs of the N atoms on both squares are approximately parallel.
Physicochemical Properties of Polyacrylates Containing Tetraphenylporphinatocobalt(II) and Chloro(tetraphenylporphinato)iron(III) as Side Chains
Authors: Kamachi Mikiharu , Shibasaka Mahito , Kajiwara Atushi , Mori Wasuke , Kishita Michihiko
Published: July 2006

Polyacrylates containing tetraphenylporphinatocobalt(II) (TPP-Co(II)) and chloro(tetraphenylporphinato)iron(III) (TPP-Fe(III)Cl) as side chains were prepared. Their physicochemical properties were investigated by UV-visible spectroscopy, ESR spectroscopy, and magnetic susceptibility (χM) measurement. In comparison of the visible spectra of polymers with those of the corresponding monomers, hypochromism of the Soret band and some of Q bands was observed in both polymers. In the measurements of ESR spectra, hyperfine splitting constants and anisotropic g-values of TPP-Co(II) or -Fe(III)Cl moieties bound to the polymers were somewhat different from those of TPP-Co(II) and -Fe(III)Cl, respectively. These differences in spectroscopic behavior suggest that there are some interactions between porphinatometal ion moieties in the polymers. The values of χM for the polymers containing TPP-Co(II) were found to obey the Curie–Weiss law with θ=190 K, which was explained in terms not only of spin-orbit interaction of the Co(II) ion but also antiferromagnetic interaction among the Co(II) ions. The magnetic moment of the TPP-Co(II) moiety bound to the polymer is smaller than that of TPP-Co(II), indicating occurrence of an antiferromagnetic interaction between Co(II) ions in the polymer. The values of χM for polymers containing TPP-Fe(III)Cl were found to obey the Curie–Weiss law with θ=20 K. This can be explained in terms of the presence of antiferromagnetically-interacting sites. From the experimental results, it is concluded that the antiferromagnetic interaction between TPP-metal ions bound to the polymer is larger than that of the corresponding TPP-metal ions. Molecular oxygen is adsorbed to polyAOTPP-Co(II) and 5-(4-propanoyloxyphenyl)-10,15,20-triphenylporphinatocobalt(II) (POTPP-Co(II)) below 180 K. Magnetic susceptibility measurement and ESR study show that molecular oxygen is bound to the Co(II) ion by chemisorption whose binding energy is 24 kJ M−1.
Adsorption at Water/ Air Interface and Micelle Formation of Decylammonium Bromide and Decylammonium Chloride Mixture
Authors: Matsuki Hitoshi , Ando Naoko , Aratono Makoto , Motomura Kinsi
Published: July 2006

The surface tension of the aqueous solution of decylammonium bromide (DeAB) and decylammonium chloride (DeAC) mixture was measured as a function of the total molality and composition of surfactants at 298.15 K under atmospheric pressure. By applying the thermodynamic equations derived previously to the experimental results, the compositions in the mixed adsorbed film and mixed micelle were evaluated. It was found that the adsorbed film and micelle are rich in DeAB, which is more surface active than DeAC, compared with the aqueous solution. Further, the DeAB and DeAC molecules were concluded to mix ideally in the states of the adsorbed film and micelle. On the other hand, the compositions were compared with those of dodecylammonium chloride (DAC)–DeAC mixture at the critical micelle concentration (cmc). The discrepancy between the compositions was proved to be related closely to the differences between the cmc’s and between the surface tension values at the cmc of pure surfactants.
The Electric Birefringence and Dichroism of a Nonlinear Optical Compound, 4-[2-[4-(Dimethylamino)pheny]ethenyl]-1-ethylpyridinium Iodide, in the Presence of Poly(p-styrenesulfonate) and Poly(l-α-glutamate) in Solutions
Authors: Yamaoka Kiwamu , Hino Yasumori
Published: July 2006

The pulsed electric birefringence at 633 nm and dichroism at 462 nm of the title cationic compound (DAES) were measured at 20 °C over a wide electric field strength range (0.1–24 kV cm−1) in the presence of poly(p-styrenesulfonate) (NaPSS) and poly(l-α-glutamate) (PGA) in aqueous solutions at various mixing ratios (P/D) of the polymer to the ligand. The steady-state electric birefringence δ of NaPSS–DAES complexes was positive, while that of NaPSS was negative. The optical anisotropy factor of bound DAES was responsible for the sign reversal. The reduced electric dichroism of NaPSS–DAES at a P/D of 1.9 was +0.38 at infinitely high fields. A value of ±50° was found for the average angle between the orientation axis of the complex and the direction of the optical transition moment at 462 nm of bound DEAS chromophores. No appreciable permanent dipole moment was present in any of the NaPSS–DAES systems. The field orientation was due mostly to counterion-induced moments. The rotational relaxation time was determined from the decay signals. For PAG–DAES and PGA at pH 6.4 and 4.1, the sign of δ was always positive, the magnitude differing from each other by only 10–20%.
Copper(I) Salt Catalyzed Reaction of 1,1,1-Trichloro-2,2,2-trifluoroethane with Trimethylsilyl Enol Ethers. A Convenient Synthesis of β-Chloro-β-(trifluoromethyl) α,β-Unsaturated Carbonyl Compounds
Authors: Okano Takashi , Uekawa Toru , Eguchi Shoji
Published: July 2006

β-Chloro-β-(trifluoromethyl) α,β-unsaturated carbonyl compounds were obtained by the reaction of trimethylsilyl enol ethers with CF3CCl3 and CuCl, followed by dehydrochlorination with triethylamine or DBN. Aromatic enol ethers gave moderate to good yields of the chloro(trifluoromethyl)methylene ketone derivatives but aliphatic enol ethers and silyl ketene acetal gave only lower yields.
The Synthesis of 4,5-Ethylenedithio-4′,5′-vinylenedithiotetrathiafulvalene (EVT) and Its Methyl and Dimethyl Derivatives (EMVT, EDMVT), and the Molecular and Crystal Structures of EVT
Authors: Nakano Hideyuki , Miyawaki Kenji , Nogami Takashi , Shirota Yasuhiko , Harada Shigeharu , Kasai Nobutami
Published: July 2006

New donor molecules, 4,5-ethylenedithio-4′5′-vinylenedithiotetrathiafulvalene (EVT) and its methyl and dimethyl derivatives (EMVT and EDMVT), were synthesized for the study of conducting organic salts. They are unsymmetrical TTF derivatives possessing moieties of both BEDT-TTF and bis(vinylenedithio)tetrathiafulvalene (VT) or its methyl and dimethyl derivatives. Their oxidation potentials were measured and then compared with those of the related donor molecules. The X-ray crystal structure analysis of EVT revealed that its molecular and crystal structures are very close to that of BEDT-TTF.
Cobalt(III) Complexes with Quadridentate Ligands. IX. High-Resolution Solid-State 13C CP/MAS NMR Spectra of the Salicylato-, Carbonato-, Dichloro-, and Dinitro(quadridentate amine)cobalt(III) Complexes
Authors: Yamamoto Yoshihisa , Toyota Eiko , Shimokawa Shigezo
Published: July 2006

High-resolution solid-state 13C CP/MAS NMR was applied to many cobalt(III) complexes, such as salicylato-, carbonato-, dichloro-, and dinitro(quadridentate amine)cobalt(III) complexes, [CoL2(quadridentate amine)]+ (L: 1/2sal, 1/2CO3 Cl, NO2; quadridentate amine: tren, trien, 2,3,2-tet, 3,2,3-tet, 3,3,3-tet). The signals of the methylene carbons of the coordinated quadridentate amine ligands in their complexes have been assigned to the center, NH2– side, NH– side, and N– side methylene carbons. Also, the signals of the ring carbons of the coordinated salicylato ligand in their complexes have been assigned to the individual carbon atoms. It has been found that the signals of nonprotonated carbons (C-1, C-2, and C-7) of the coordinated salicylato ligand have been very high and that the 13C CP/MAS NMR method is well-suited for studies of unstable compounds in solutions.
Hydrogenation of Carbon Dioxide on Unpromoted and Potassium-Promoted Iron Catalysts
Authors: Lee Min-Dar , Lee Jyh-Fu , Chang Chau-Shang
Published: July 2006

The promotional effect of potassium was studied on catalytic behavior of iron in CO2 hydrogenation. A higher product selectivity toward light olefins and long-chain hydrocarbons was obtained on promoted catalyst than on unpromoted catalyst. This can be attributed to the enhancement of carburization on iron catalyst by potassium, as evidenced by Mössbauer spectroscopy and temperature-programmed decarburization.
A Transition Sequence of Complex Oscillations in a Chemical Oscillation Model Showing Chaos
Authors: Morita Makoto , Iwamoto Kazutoshi , Sen\={o} Manabu
Published: July 2006

A three-variable model system exhibiting complex oscillations was analyzed. Our analysis reveals a bifurcation structure of complex oscillations including chaotic oscillations. The bifurcation structure reproduces well the transition sequences of oscillatory states observed in the experiments of the Belousov–Zhabotinskii reaction and the chlorite oscillators. The transition sequence to chaotic oscillations in our model system shows period-doubling sequences. When the number F is defined as a ratio of the number of large amplitude to the total number of oscillations per period in the complex oscillation, the number constitutes a monotonous, stepwise-increasing function of a control parameter. The sequence of the complex oscillations is described well by the Farey arithmetric. Also, the average flux of reaction was found to change abruptly at the bifurcation points of the complex oscillations.
Synthesis and Chromogenic Properties of Disulfonated (1-Naphthyl)(2-quinolyl)methanone 5-Nitro-2-pyridylhydrazone and Its Application to the Spectrophotometric and Analogue-Derivative Spectrophotometric Determination of Trace Amounts of Zinc
Authors: Ishii Hajime , Kohata Katsunori , Odashima Tsugikatsu , Kawamonzen Yoshiaki
Published: July 2006

A water-soluble hydrazone, disulfonated (1-naphthyl)(2-quinolyl)methanone 5-nitro-2-pyridylhydrazone (NQNPH), in which one nitro group and two sulfo groups are introduced for the purpose of increasing sensitivity and solubility in water, has been synthesized and its chromogenic property and reactivity with metal ions investigated. NQNPH reacts with various metal ions including zinc(II) to form 1:2 (metal: ligand) colored stable complexes with high molar absorptivities. On this basis, sensitive and practical spectrophotometric and analogue-derivative spectrophotometric methods for the determination of trace amounts of zinc with NQNPH have been proposed. The zinc(II)–NQNPH complex is formed quantitatively in the pH range 6.9–9.6 and its absorption spectrum shows an absorption maximum at 516 nm. Beer’s law is obeyed over the range 0.07–1.5 ppm of zinc and the apparent molar absorptivity of the complex is 4.33×104 dm3 mol−1 cm−1 at 516 nm. The proposed method was applied to the determination of zinc in Kuroko and water samples, with satisfactory results. In addition, the acid dissociation constants of NQNPH and the overall formation constant of its zinc complex were also determined spectrophotometrically.
Racemization of Phenylalanine Coordinated to Bis(2,2′-bipyridine)ruthenium(II) Complexes in Basic Aqueous Solutions
Authors: Nagai Takashi
Published: July 2006

Racemization of the phenylalaninato ligand in Λ- and Δ-[Ru(phe)(bpy)2]+ (phe; phenylalaninate anion, bpy; 2,2′-bipyridine) complexes was found in basic aqueous solutions. It was proceeding without conformational change around the ruthenium ion in the dark. The equilibrium and rate constants of the racemization were determined in basic solutions at 100 °C. The reaction was base-catalyzed and not affected by photoexcitation of the complex ions.