bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamical Structures of Normal Alkanes, Alcohols, and Fatty Acids in the Liquid State as Determined by Viscosity, Self-Diffusion Coefficient, Infrared Spectra, and 13CNMR Spin-Lattice Relaxation Time Measurements
Authors: Iwahashi Makio , Yamaguchi Yoshimi , Ogura Yoshio , Suzuki Masao 
Published: July 2006

Abstract
The dynamical structures of molecules of normal alkanes (C5–C14) and normal fatty acids (C8 and C9) in the liquid state were estimated through analyses of their self-diffusion coefficients (D), viscosities (η), molar volumes, and 13CNMR spin-lattice relaxation time (T1). The apparent hydrodynamic radius evaluated from D and η for the alkanes was ca. 2.5×10−10 m and that for the fatty acids, ca. 3.1×10−10 m, irrespective of their hydrocarbon chain length: The former value is almost equal to that of the van der Waals radius (2.4×10−10 m) of the cross section of a hydrocarbon chain; the latter is in agreement with that of the normal alcohols reported in a previous paper. It is thus concluded that in the pure liquid of a rod-like compound such as normal alkane, alcohol, and fatty acid, the free rotational (end-over-end) as well as the transverse motion of the rod-like molecule is severely restricted due to the entanglements of the molecules; only a longitudinal translation is allowed. In addition, the infrared-spectrum results suggest that a unit in translational motion for a normal fatty acid is a dimer.
The Amino-Imino Tautomerization of 2,6-Diaminopyridine by Interaction with Ethanol
Authors: Inuzuka Kozo , Fujimoto Akira 
Published: July 2006

Abstract
The UV absorption spectrum of 2,6-diaminopyridine was measured in an ethanol-and-isooctane mixed solvent while increasing the concentration of ethanol at room temperature and changing the temperature from 20 to −100°C at a constant concentration of ethanol. Its spectrum showed a clear shoulder band near 345 nm as the concentration of ethanol increased to over 5×10−1 mol dm−3 at room temperature and as the temperature decreased from 20 to −100°C in 1×101 mol dm−3 of ethanol in the isooctane solution. The corresponding band near 345 nm was observed for 2-amino-6-methylaminopyridine and 2,6-bis(methylamino)pyridine; however, it was not found for 2-amino-6-dimethylaminopyridine, 2-methylamino-6-dimethylaminopyridine, or 2,6-bis(dimethylamino)pyridine in the same experiments. The shoulder band near 345 nm was, on the basis of the spectroscopic results and the molecular orbital method, assigned to the π–π* absorption band of the (E)-6-amino-2(1H)-pyridinimine formed through the hydrogen-bond formation of 2,6-diaminopyridine with two ethanols. The formation of the imino form with two ethanols may be restricted to the 2,6-diaminopyridine and its methyl derivatives, in which each amino group at the 2- and 6-positions has at least one hydrogen atom. The proton transfer from ethanol to 2,6-diaminopyridine in the 2,6-diaminopyridine-ethanol complex may be energetically difficult in the ground state.
Syntheses of 22,23-Dihydro-1α,25-dihydroxyvitamin D2 and Its 24R-Epimer, New Vitamin D2 Derivatives
Authors: Tsuji Masahiro , Yokoyama Shinji , Tachibana Yoji , Ikekawa Nobuo 
Published: July 2006

Abstract
New 1α,25-dihydroxy vitamin D2 derivatives (22,23-dihydro-1α,25-dihydroxyvitamin D2 (2a)) and its 24R-epimer (2b), were synthesized by two procedures. 22-Oxo-5α,8α-(4-phenyl-3,5-dioxo-1,2,4-triazolidine-1,2-diyl)-23,24-dinor-6-cholene-1α,3β-diyl diacetate (8), obtainable readily from ergosterol, was converted to 22-phenylsulfonyl-5α,8α-(4-phenyl-3,5-dioxo-1,2,4-triazolidine-1,2-diyl)-1α,3β-bis(tetrahydropyranyloxy)-23,24-dinor-6-cholene (14) or 22-iodo-5α,8α-(4-phenyl-3,5-dioxo-1,2,4-triazolidine-1,2-diyl)-1α,3β-bis(tetrahydropyranyloxy)-23,24-dinor-6-cholene (16). Condensation of the C-22 sulfone (14) with (3R)-4-iodo-2,3-dimethyl-2-butanol THP ether, or the C-22 iodide (16) with (3R)-2,3-dimethyl-4-phenylsulfonyl-2-butanol THP ether followed by desulfonylation and successive deprotection gave 5,7-ergostadiene-1α,3β,25-triol (21a), which led to 2a upon irradiation and subsequent thermal isomerization. Similarly, a 24R-epimer of 2a was synthesized.
An Ab Initio Molecular Orbital Study on the Ene Reaction of Methyl Acrylate with Propene
Authors: Uchimaru Tadafumi , Tsuzuki Seiji , Tanabe Kazutoshi , Hayashi Yujiro 
Published: July 2006

Abstract
The exo and endo transition structures for the ene reaction of methyl acrylate with propene have been located with RHF calculations at the 3-21G and 6-31G levels. Energetics have been evaluated with the 6-31G* basis set and MP2 correlation energy correction. The transition-state geometries and the calculated energetics have been compared with those for the parent ene reaction between ethylene and propene. The exo and endo transition structures resemble rather closely that for the parent ene reaction. Reasonable substituent effects are indicated on activation energies and extents of electron transfer in the transition states. According to the calculated overlap populations, the transition structures for methyl acrylate ene reaction have less asynchronous character in the bond reorganization as compared with the parent ene reaction. The relatively small stability difference between exo and endo transition structures suggests that intrinsic exo/endo selectivity in the ene reactions is not so obvious as in the Diels–Alder reactions.
The Lactam–Lactim Tautomerization of Monoamino-Substituted 2-Pyridinols in Tetrahydrofuran
Authors: Fujimoto Akira , Inuzuka Kozo 
Published: July 2006

Abstract
MINDO/3 calculations have been performed on 3-amino-, 4-amino-, 5-amino-, and 6-amino-2-pyridinols to estimate their molecular geometries. The lactam-lactim tautomerization from amino-2-pyridone to amino-2-pyridinol was expected for 5-amino- and 6-amino-2-pyridinols from the MINDO/3 calculations. In addition, their dimer formation energies were evaluated by the CNDO/2 method. Among the four amino-2-pyridones, 6-amino-2-pyridone has the largest dimer formation energy and 3-amino-2-pyridone the smallest. Furthermore, to certify the tautomerization of 3-amino-, 5-amino-, and 6-amino-2-pyridinols the UV absorption and fluorescence spectra were measured, and compared with those of their O-methyl and nuclear N-methyl derivatives. From the UV spectral data the equilibrium constants of the lactam–lactim tautomerization were determined for 5-amino and 6-amino derivatives in tetrahydrofuran (THF) at various temperatures. The lactam form is more stable than that of the lactim; the enthalpy changes between two forms of 5-amino and 6-amino derivatives were estimated to be 7.9 and 6.3 kJ mol−1, respectively. The lactam and lactim dimers of these two derivatives were found to be easily formed in THF and ether. From the fluorescence spectral data the lactim dimer of 6-amino derivative was found to be formed in the lowest excited π,π* singlet state. On the other hand, the 3-amino derivative exists predominantly in the lactam monomer form in both the ground and the lowest excited π,π* singlet states.
The Pyrolysis of 1,2,3,4,6,7-Hexathia-5,8-diazocine
Authors: Kudo Yoshiyuki , Kimura Teruyoshi , Hamada Shuichi 
Published: July 2006

Abstract
Crystals of 1,2,3,4,6,7-hexathia-5,8-diazocine (1,4-S6(NH)2) were transformed around 363 K with a molar enthalpy change of the transformation of 2.40±0.07 kJ mol−1. Crystal systems of the two forms of 1,4-S6(NH)2 were identified to be orthorhombic (α-form) and monoclinic (β-form) below and above this temperature. Molar heat capacities of the α- and β-forms were also deduced as being 0.1950±0.001 and 0.199±0.001 kJ mol−1 K−1 at 298.15 K, respectively. The 1,4-S6(NH)2 was pyrolyzed around its apparent melting point (405 K), producing tetrasulfur tetranitride (S4N4) and tetrasulfur dinitride (S4N2) as solid intermediates, which finally decomposed into sulfur, nitrogen, and ammonia under an argon atmosphere. A stoichiometric correlation among the final products gave an overall pyrolytic equation: 1,4-S6(NH)2=3⁄4S8+2⁄3N2+2⁄3NH3. The standard enthalpy of the formation of α-form 1,4-S6(NH)2 was estimated as being 158±2 kJ mol−1 according to the observed enthalpy changes of the pyrolysis and transformation, which reasonably agreed with that calculated.
Vapor-Phase Carbonylation of Methanol over Tin-on-Active Carbon Catalysts
Authors: Yagita Hiroshi , Omata Kohji , Shikada Tsutomu , Fujimoto Kaoru 
Published: July 2006

Abstract
It was found that a number of metals or metal oxides showed catalytic activities for the vapor-phase carbonylation of methanol in the presence of methyl iodide (CH3I) promoter under the conditions of 250°C and 10 atm (1 atm=1.01325×105 Pa), when they were supported on active carbon. Particularly, tin and lead showed high activities. The catalytic activity of the metallic tin increased with the process time over 5 h while that of the unreduced tin catalyst increased for more than 10 h to reach the same level. The catalytic performances of the tin on active carbon were similar to those of the nickel on active carbon which have been already reported. It was suggested that the active species of the tin catalyst was some kind of metal compounds which was highly dispersed on active carbon and was able to be incorporated in the redox cycle.
The Effect of Alternating Magnetic Field on the Magnetic Anisotropic Gel Beads Immobilized Catalase
Authors: Sakai Yasuzo , Kuwahata Mitsuyoshi , Takahashi Fujio 
Published: July 2006

Abstract
It has been reported that magnetic anisotropic gel beads (MA gel beads) prepared by the gelation of a ferrite suspension in a static magnetic field have a property of oscillating in an alternating magnetic field. This paper presents the results concerning the application of MA gel beads to a study of immobilized enzymes. MA gel beads were prepared by the gelation of a suspension containing 5% catalase, 3.5% κ-carrageenan and 0–17% Sr-ferrite in a static magnetic field of 500–2500 Oe (1 Oe=1⁄4π×103 Am−1). The enzyme reaction was carried out in a column, which was filled with MA gel beads, by continueously flowing a solution containing H2O2 as a substrate. It was found that \ding172 MA gel beads oscillated intensely upon applying an alternating magnetic field of 100–600 Oe, 50 Hz in the column, \ding173 the concentration of O2 in the elution that passed through the column increased by 10–60% compared with that in the absence of a magnetic field, and \ding174 the concentration of O2 in the elution was influenced by the strength of the alternating magnetic field, the strength of the static magnetic field and the concentration of ferrite in the gel.
Thermal Reactions of N,N-Dimethyl-1,2-ethanediamine Complexes of Nickel(II) in the Solid State
Authors: Koner Subratanath , Ghosh Ashutosh , Ray Chaudhuri Nirmalendu 
Published: July 2006

Abstract
Complexes [NiL2(H2O)X]X·nH2O (L=N,N-dimethyl-1,2-ethanediamine; n=0 when X=BF4; n=1 when X=Br; n=3 when X= Cl), [NiL2(H2O)Y]·nH2O (n=2 when Y= SeO4; n=5 when Y=SO4), [NiL2(H2O)2](NO3)2·H2O and [NiL2] (ClO4)2 have been synthesized and investigated thermally in the solid state. The complexes [NiL2(H2O)Cl]Cl·3H2O, [NiL2(H2O)Br]Br·H2O, [NiL2(H2O)(SO4)]·5H2O, and [NiL2(H2O(SeO4)]·2H2O possess trans octahedral geometry and undergo deaquation-anation associated with trans→cis isomerization upon heating in the solid state whereas on deaquation the complex [NiL2(H2O)2](NO3)2·H2O retains its trans octahedral configuration. The complex [NiL2(H2O)(BF4)](BF4) possesses cis octahedral geometry and on thermal deaquation it transforms to a square planar complex. The complex [NiL2](ClO4)2 is square planar and undergoes a yellow → red thermochromic phase transition on heating (203–216°C; ΔH=6.9 kJ mol−1). The red isomer is also square planar. The species [NiLCl2], [NiL(SO4)] and NiL0.33Cl2 have been synthesized pyrolytically in the solid state from their corresponding parent diamine complexes. The complexes [NiLCl2] and [NiL(SO4)] possess octahedral geometry. NiL0.33Cl2 possesses an unusually high magnetic moment (4.1 BM at 28°C).
Reduction of CO2 by Halobacterium Halobium MMT22 to Formic Acid
Authors: Taqui-Khan Mirza Mohammad , Bhatt Jayshree 
Published: July 2006

Abstract
Photobiological and photoelectrochemical conversion of CO2 to formic acid was achieved by using Halobacterium halobium MMT22. The yield of formic acid increased considerably by regenerating NADH by cathodic reduction at −0.60 V or in the presence of the two-electron donor ascorbic acid. Under photoelectrochemical reduction, maximum yield of 0.2 mol of HCOOH/mg cells/h was obtained, the highest reported so far.
Reaction Mechanism between Pyruvic Acid and Aromatic Amines
Authors: Tapia I , Alcázar V , Morán J R , Grande M 
Published: July 2006

Abstract
The formation of the condensation products obtained when pyruvic acid and aromatic amines are allowed to react, can be explained by condensation of one mole of the imine of pyruvic acid with one mole of the enamine isomer, either through the C atom or through the N atom, followed by elimination and lactonization to give a γ-lactone carboxylate or an azlactone carboxylate, which on decarboxylation give an iminobutanolide or an azlactone respectively. Aminolysis of these cyclic intermediates led to the formation of the final products.
Liquid-Liquid Extraction of Palladium(II) with Phenylene-incorporated Tetrakis(thioether)s
Authors: Chayama Kenji , Sekido Eiichi 
Published: July 2006

Abstract
Extraction behaviors of palladium(II) with three cyclic and noncyclic phenylene-incorporated tetrakis(thioether)s were examined. Picrate ion as a counter anion and 1,2-dichloroethane as an extraction solvent were used. The extractability of palladium ion with the acyclic tetrakis(thioether) used in this study was higher than that with the corresponded cyclic one.
The Magnetic Properties of Copper(II) 3- and 5-Substituted 2-Pyridinolates
Authors: Emori Shuji , Furukawa Ryuichi , Nakashima Shoichi 
Published: July 2006

Abstract
The N,N-dimethylformamide adducts of copper(II) 3- and 5-substituted 2-pyridinolates were prepared, and then characterized by means of magnetic susceptibility and IR-spectroscopy. The variation in their magnetic moments is discussed in terms of the basicities of the parent 2-pyridones.
Photolysis of Pyridylmethyl- and Pyridiniomethylphosphonic Acids
Authors: Okamoto Yoshiki , Kokubo Ichiro , Takamuku Setsuo 
Published: July 2006

Abstract
Upon UV-irradiation, the C–P bond of (4-pyridylmethyl)phosphonic acid cleaved only near the isoelectronic point to give 4-methylpyridinium phosphate, while (1-benzyl-4-pyridiniomethyl)phosphonic acid underwent C–P bond cleavage above pH 4 to give 1-benzyl-4-methylpyridinium phosphate. On the other hand, the C–P bond of (2-pyridylmethyl)phosphonic acid cleaved under pH region of about 1 to 2, while (1-benzyl-2-pyridiniomethyl)phosphonic acid underwent C–P bond cleavage above pH 4.
Naphthaceno[1-12-cd:4,5-c′d′]bis[1,2]diselenole as a New Electron Donor
Authors: Miyamoto Hisakazu , Aso Yoshio , Otsubo Tetsuo , Ogura Fumio 
Published: July 2006

Abstract
The title compound, an isomeric TSeT, was prepared as the first example of unsymmetrical peridichalcogenide derivatives of naphthacene. Like symmetrical TSeT, it is a good electron donor and forms electrically high-conductive complexes with various electron acceptors.
Ethyl 2-(Diphenylmethyleneamino)acrylate as a Dienophile in the Synthesis of Alicyclic α-Amino Acids
Authors: Cativiela C , Fraile J M , Mayoral J A 
Published: July 2006

Abstract
Ethyl 2-(diphenylmethyleneamino)acrylate behaves as an excellent dienophile with cyclopentadiene. This reaction constitutes a new and improved procedure for the synthesis of 2-aminonorbornane-2-carboxylic acids.
The Structure of the Cyclodextrin Complex. XXII. Crystal Structures of Hexakis(2,6-di-O-methyl)-α-cyclodextrin Complexes with 1-Propanol and Iodine. Evidence for the Formation of Iodine-Host Charge-Transfer Complex
Authors: Harata Kazuaki 
Published: July 2006

Abstract
Crystal structures of hexakis(2,6-di-O-methyl)-α-cyclodextrin complexes with 1-propanol and iodine were determined by X-ray analysis. Crystals of both complexes are isomorphous and the space group is P21 with cell dimensions: a=14.136(2), b=10.680(1), c=21.479(2) Å, and β=106.00(1)° for the 1-propanol complex and a=14.124(2), b=10.667(2), c=21.443(3) Å, and β=106.29(1)° for the iodine complex. The structures were solved by the R-map method combined with the rigid-body least-squares technique and refined by the block-diagonal least-squares method to the R-value of 0.058 for the 1-propanol complex and 0.094 for the iodine complex. The host molecules are arranged in a herring-bone fashion to form a typical cage-type packing structure. Both guest molecules are included within the “cage” which is created by the block of both ends of the annular host cavity by adjacent molecules. The 1-propanol molecule is in van der Waals contact with the inside wall of the host cavity, whereas the iodine molecule forms a charge-transfer complex with an O(3)H hydroxyl group of the adjacent host.
Electronic Structure of β-Carboline Anhydro-Bases
Authors: Aihara Jun-ichi , Ichikawa Hiroshi , Tokiwa Hiroaki , Okumura Yasuaki 
Published: July 2006

Abstract
β-Carboline anhydro-bases generally have a large positive topological resonance energy although they apparently disobey the rule of topological charge stabilization (TCS rule). π-Electron densities and molecular geometries calculated at the STO-3G+ level support the view that the dipolar aromatic structure contributes appreciably to the stability of β-carboline anhydro-bases. However, these molecules are still worse in energy than the isomeric β-carbolines. Protonated anhydro-bases or β-carbolinium ions conform to the TCS rule. All biogenic β-carboline anhydro-bases must be protonated in living organisms.
A Conductance Study of Macrocyclic Schiff Base Metal(II) Complexes in Methanol
Authors: Liu Jianhua , Masuda Yoshitaka , Sekido Eiichi 
Published: July 2006

Abstract
The first ionic association constants between five macrocyclic Schiff base metal(II) complexes (cation and perchlorate or thiocyanate anion) were determined by conductometric measurements in methanol at 25 °C by using a modified Onsager limiting equation, according to Fuoss and Edelson method. The limiting equivalent conductivities of the chelate cations of these complexes were calculated. These results were used to evaluate the performance of coated-wire perchlorate ion-selective electrodes (PCWE) based on these complexes.
Molecular Structure of 9-Chloromethyl-1,4-dimethoxytriptycene and Its Implications for the Presence of O···CH2C1 Interactions
Authors: Tamura Yoshio , Takizawa Hiroo , Yamamoto Gaku , Oki Michinori , Murata Shigeru 
Published: July 2006

Abstract
Changing the substituent at the 4-position of 9-chloromethyl-1-methoxytriptycene shows that the nitro group increases the sc conformation whereas the methoxyl group favors the ap conformation in a relative sense, as judged from the 1H NMR spectra at low temperatures. Examination of rotational barriers, solvent effects, and thermodynamic parameters has not been able to distinguish three possibilities, O···CH2Cl interactions, head-to-tail arrangement of two dipoles, and van der Waals repulsions as a main cause for the observed population change. X-Ray crystallographic analyses of the title compound and related ones suggest that in the crystalline state the 1-methoxyl group in the title compound takes an anomalous conformation in which the group is nonplanar with the benzeno bridge. This feature was not observed in 1,4-dimethoxy-9-methyltriptycene. This structural feature is attibuted to the presence of O···CH2Cl interactions in the title compound and eliminates the van der Waals repulsion and the head-to-tail arrangement of two dipoles from being the main cause that favors the ap form.
Rearrangement of 3-(Trimethylsilylmethylthio)allyllithium
Authors: Miura Katsukiyo , Oshima Koichiro , Utimoto Kiitiro 
Published: July 2006

Abstract
Proton abstraction from 3-trimethylsilylmethylthio-1-propene by butyllithium followed by treatment with iodomethane provided 1-methylthio-4-trimethylsilyl-1-butene. Meanwhile, 1-trimethylsilylmethylthio-2-butene afforded 3-methyl-4-methylthio-1-trimethylsilyl-1-butene upon successive treatment with butyllithium and iodomethane.
A New Amperometric Glucose Sensor Based on Bilayer Film Coating of Redox-Active Clay Film and Glucose Oxidase Enzyme Film
Authors: Ohsaka Takeo , Yamaguchi Yoshio , Oyama Noboru 
Published: July 2006

Abstract
A new amperometric glucose sensor based on bilayer film coating has been fabricated and its sensor characteristics under a steady-state condition have been examined. The electrode substrate was coated with two kinds of polymer films in a bilayer state, i.e., first with the redox-active montmorillonite clay film into which [Ru(NH3)6]3+ complexes are incorporated electrostatically and they function as an electron shuttle which delivers electrons to redox-active sites in the clay film, and then with the enzyme film consisting of bovine serum albumin and glucose oxidase (GOx). The glucose concentration could be monitored by measuring the current for H2O2 reduction electrocatalyzed by the inner clay film where H2O2 was produced by the glucose–GOx enzyme reaction in the outer enzyme film. The mechanism of the overall electrode/enzyme reaction for this amperometric glucose sensor is represented as follows:
(Remark: Graphics omitted.)
where reactions 1,2,3, and 4 correspond to the glucose–glucose oxidase enzyme reaction, the hydrolysis reaction of d-glucono-δ-lactone, the electrocatalytic reduction of H2O2 by the montmorillonite clay containing [Ru(NH3)6]2+ and the electrode reaction of the [Ru(NH3)6]2+⁄3+ couple, respectively. The reproducible relationship between glucose concentration and sensor output was obtained. The sensitivity and the dynamic range were found to depend on the amount of GOx confined in the enzyme film and its thickness.
NAD(P)+-NAD(P)H Models. 72. Isotope Effects to Prove the Multi-Step Mechanism in the Reduction with an NAD(P)H Analog
Authors: Goto Mutsuo , Mikata Yuji , Ohno Atsuyoshi 
Published: July 2006

Abstract
Reduction of 1,4-benzoquinone and its various derivatives with 1-benzyl-1,4-dihydronicotinamide (BNAH) and its 4-deuteriated derivative was studied. The kinetic deuterium primary isotope effect (kH⁄kD) for this reaction appears always larger than the isotopic ratio in the product, BNA+(YH⁄YD; product isotope effect). In the absence of magnesium ion, YH⁄YD increases as the substrate becomes less electron-demanding. In the presence of magnesium ion which accelerates the reaction, YH⁄YD stays small whereas kH⁄kD is not affected. The results reveal that the reaction proceeds with a multi-step mechanism in which the product-determining and rate-determining steps differ each other.
A Simple Synthetic Method of trans-5-Aryl and 5-Cyclopropyl Derivatives of 2-Isoxazolin-4-ol via Intramolecular Ring Opening of α,β-Epoxy Ketone Oximes
Authors: Ito Shoei , Sato Masahiro 
Published: July 2006

Abstract
trans-5-Aryl and 5-cyclopropyl derivatives of 2-isoxazolin-4-ol were conveniently prepared from trans-2-aryl- and 2-cyclopropyl-3-benzoyloxiranes and hydroxylamine hydrochloride in the presence of pyridine via an intramolecular opening of oxirane by the oxygen nucleophile of the oxyimino group.