bluuebunny/crossref_metadata_2025_split huggingface dataset:
Restricted Rotation Involving the Tetrahedral Carbon. LVI. NMR and Molecular Mechanics Studies on the Stereodynamics of 8,13-Dichloro-9-methoxy-1,4-dimethyltriptycene
Authors: Yamamoto Gaku , Oki Michinori 
Published: July 2006

Abstract
The 400 MHz 1H NMR spectrum of the title compound at −100 °C in dichloromethane revealed the presence of two isomers in a ratio of 88 : 12, which results from restricted rotation about the triptycyl–oxygen single bond. The major isomer was assigned to the ap rotamer on the basis of the low temperature 13C NMR spectrum. Dynamic NMR studies gave the activation parameters for the ap→±sc conversion: ΔH\eweq=11.9±0.5 kcal/mol (1 calth=4.184 J), ΔS\eweq=2.6±2.5 eu, ΔG\eweq200K=11.4 kcal/mol. Results of molecular mechanics calculations on the compound are discussed.
Substituent Effects on Azomethine Proton Chemical Shifts and 13C–H Coupling Constants in N-Benzylideneanilines. Generality of Inverse Substituent Effects on the Azomethine Proton Chemical Shifts
Authors: Akaba Ryoichi , Sakuragi Hirochika , Tokumaru Katsumi 
Published: July 2006

Abstract
Azomethine proton chemical shifts were measured for series of N-benzylideneanilines; C6H5CH=NC6H4X-4, 4-YC6H4CH=NC6H5, 4-NMe2C6H4CH=NC6H4X-4, 4-YC6H4CH=NC6H4NMe2-4, 4-NO2C6H4CH=NC6H4X-4, 4-YC6H4CH=NC6H4NO2-4, and 4-YC6H4CH=NC6H3(CH3)2-2,6. It was found that for N-benzylideneanilines carrying the variable substituents X on the anilino benzene ring the azomethine protons undergo upfield shifts with increasing electron-withdrawing property of X, whereas those for N-benzylideneanilines carrying the variable substituents Y on the benzylidene benzene ring exhibited expected lowfield shifts with increasing electron-withdrawing property of Y. 13C–H coupling constants for azomethine carbon–hydrogen bonds (J(13C–H)) were also measured for several derivatives of 4-NO2C6H4CH=NC6H4X-4, 4-YC6H4CH=NC6H4NO2-4, and 4-YC6H4CH=NC6H3(CH3)2-2,6. In contrast with the substituent effects on the azomethine proton chemical shifts, the coupling constant increases with increasing electron-withdrawing property of the substituent X or Y, regardless of the position of the substituents, indicating that a through-bond electronic effect of the substituent is a predominant factor to determine the magnitude of the coupling constant. These results show that the anomalous substituent effects on the azomethine proton chemical shifts are a general phenomenon in N-benzylideneanilines which carry variable substituents on the anilino benzene ring, and support our previous proposition that the anomaly is likely to originate primarily from the change of molecular conformation of these N-benzylideneanilines in solution.
Structural Study of Germanate Glasses Irradiated with γ-Rays and Thermal Neutrons
Authors: Nishida Tetsuaki , Katada Motomi , Takashima Yoshimasa 
Published: July 2006

Abstract
119Sn Mössbauer study of 60Co-γ ray and thermal neutron irradiated potassium germanate glasses containing a small amount of SnO2 has been performed to investigate the structural change of the glasses. The γ- and the thermal neutron-irradiation results in a disappearance of the distinct composition dependence of the Mössbauer parameters (quadrupole splitting and linewidth) observed before the irradiation. DTA measurement of the irradiated glasses also reveals drastic decreases in glass transition temperature (Tg) amounting to 20–120 °C and a simultaneous disappearance of the distinct composition dependence of Tg observed before the irradiation. This suggests a disruption of the chemical bond between germanium and oxygen atoms constituting GeO6 units. On the other hand, Mössbauer measurement at lower temperatures reveals that a parameter of intermolecular force constant (θ2M) obtained from the temperature dependence of the absorption area undergoes little change by the irradiations. This suggests that the irradiations bring about little changes in the ionic bond and the interatomic distance between tin and oxygen atoms, and that the irradiated germanate glasses can still be regarded as polymers from the lattice vibrational point of view.
Formation and Reaction of Carbonyl Ylides. 1,3-Dipolar Cycloaddition of 2-Benzopyrylium-4-olates with Carbonyl Compounds
Authors: Ibata Toshikazu , Toyoda Jiro 
Published: July 2006

Abstract
Cyclic orthoester type 1,3-dipolar cycloadducts of 1-methoxy-2-benzopyrylium-4-olate with carbonyl compounds were obtained in high yields in the copper(II) acetylacetonate-catalyzed decomposition of o-methoxycarbonyl-α-diazoacetophenone in the presence of carbonyl compounds such as substituted benzaldehydes, acetaldehyde, propionaldehyde, isobutyraldehyde, pivalaldehyde, acetone, methyl ethyl ketone, methyl isopropyl ketone, 1,3-dichloroacetone, substituted acetophenones, benzoyl cyanides, cyclopentanone, cyclohexanone, 1-indanone, 9-fluorenone, anthrone, and anthraquinone. However, methyl t-butyl ketone, benzophenone, and xthanthone gave no adduct. Aldehydes and asymmetric ketones gave endo- and exo-adducts. The regiochemistry and stereochemistry of the adducts of aldehydes were determined on the basis of their coupling constants of methine protons. The reactions of p-methoxyphenyl o-diazoacetylbenzoate also gave similar 1,3-dipolar adducts. When carbonyl compounds of medium reactivity were used as a substrate, 2 : 1-adduct was obtained together with the 1 : 1-adduct. The formation of the 2 : 1-adduct was attributed to the competitive reaction of the corrsponding benzopyrylium-4-olate intermediate toward the carbonyl compounds and 1 : 1-adduct. The regiospecificity of the 1 : 1-cycloaddition was explained according to the frontier orbitals calculated by STO-3G method.
New Quassinoid Glucosides, Picrasinoside-A, -B, -C, -D, -E, -F, and -G and New Hemiacetals, Picrasinol-A and -B, from the Stem Bark of Picrasma ailanthoides PLANCHON
Authors: Okano Masayoshi , Fujita Tomoyuki , Fukamiya Narihiko , Aratani Takaaki 
Published: July 2006

Abstract
New quassinoid glucosides, picrasinoside-A, -B, -C, -D, -E, -F, and -G and new quassinoid hemiacetals, picrasinol-A and -B, were isolated from the stem bark of Picrasma ailanthoides PLANCHON, and their structures were established by spectral analyses and chemical transformations.
Liquid Crystal Materials with Sulfur Atoms Incorporated in the Principal Structure. IV. New Liquid Crystal Compounds; 2-(p-Substituted phenyl)-5-alkyl-1,3-oxathianes
Authors: Haramoto Yuichiro , Kamogawa Hiroyoshi 
Published: July 2006

Abstract
2-(p-Substituted phenyl)-5-alkyl-1,3-oxathianes, new liquid crystal compounds, were synthesized by the acetalformation reaction of the corresponding aldehydes and 2-alkyl-3-mercapto-1-propanols. The mesomorphic behaviors of these 1,3-oxathiane compounds were compared with those of the corresponding 1,3-dithianes and 1,3-dioxanes. Some of 2-(p-cyanophenyl)-5-alkyl-1,3-oxathianes exhibit monotropic nematic liquid crystal phase at room temperature, whereas 2-(p-alkoxyphenyl)-5-alkyl-1,3-oxathianes tend hardly to exhibit liquid-crystal phase. These mesomorphic characters seem to originate in the molecular width and bending at the 1,3-oxathiane ring.
Determination of the Acid Strength Distribution of Manganese Dioxide by the Modified Indicator Method
Authors: Sugiyama Kazuo , Nakano Yasushi , Miura Hiroshi , Matsuda Tsuneo 
Published: July 2006

Abstract
A new procedure for determining the distribution of acid and base centers of dark colored solids by the indicator method has been proposed. By this method weak acidic sites were found to be present on a manganese dioxide surface.
The Crystal Structures of a Dicopper(II) Complex Containing Two N4-Macrocyclic Rings Connected with an Ethylene Chain
Authors: Mikuriya Masahiro , Hamada Kosuke , Kida Sigeo , Murase Ichiro 
Published: July 2006

Abstract
The crystal structure of diaqua {7,7′ethylenebis[2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]-heptadeca-1 (17),2,11,13,15-pentaene]}dicopper(II) perchlorate dihydrate was determined by a single-crystal X-ray diffraction method. The complex assumes an extended conformation with the intramolecular Cu···Cu separation 7.081(2) or 6.985(2)Å.
NAD(P)+–NAD(P)H Model. 54. Free Radical Mechanism for the Reductive Debromination of vic-Dibromides to Alkenes
Authors: Yasui Shinro , Nakamura Kaoru , Ohno Atsuyoshi 
Published: July 2006

Abstract
vic-Dibromides undergo reductive debromination with a model of NAD(P)H, N-benzyl-1,4-dihydronicotinamide, to afford the corresponding alkenes quantitatively. Stereochemistry of the reduction suggests that the reaction involves a free radical intermediacy.
Measurement of Ultralow Interfacial Tension in the Vicinity of Critical Solution Temperature
Authors: Aratono Makoto , Motomura Kinsi 
Published: July 2006

Abstract
A new apparatus adopting the sessile drop technique has been designed to measure the ultralow interfacial tension between two liquids of a binary mixture. The equilibrium interfacial tension of the mixture of isobutyric acid and water has been determined near its upper critical solution temperature up to the value of 0.02 μN m−1.
Crystal and Molecular Structure of a Triply-thiolate-bridged Binudear Cobalt(III) Complex, [Co2{SCH(CH2CH2NH2)2}3](ClO4)3·H2O
Authors: Mikuriya Masahiro , Kida Sigeo , Ueno Shigehiro , Murase Ichiro 
Published: July 2006

Abstract
The crystal structure of tris[μ-(1,5-diamino-3-pentanethiolato)-N,N′, μ-S]-dicobalt(III) perchlorate monohydrate was determined by the single-crystal X-ray diffraction method. The binuclear complex has a novel type of binuclear structure in which the two cobalt atoms are bridged by three thiolate sulfur atoms forming a face-shared bioctahedron.
Abnormal Methyl Radicals on Alumina Surfaces
Authors: Barnes John David , Trivedi Mahendra Aruind , Oduwole Duro Abimbola , Wiseall Barrie 
Published: July 2006

Abstract
The ESR spectrum of abnormal methyl radicals on alumina surfaces is found to be symmetrical at low surface coverages. Possible mechanisms for the formation of these radicals are presented.
Interaction between 1,1′-Biacenaphthene-2,2′-diyl and Dibromomethane. Decay Kinetics in Mixed Solvents
Authors: Kobashi Harumichi , Masamoto Hiroshi 
Published: July 2006

Abstract
Interaction of the triplet biradical, 1,1′-biacenaphthene-2,2′-diyl (BR) with dibromomethane has been examined by means of transient absorption measurements and kinetic analysis. The absorption spectrum of BR in CH2Br2 shows a red shift compared with those in other solvents with various polarities. The spectral result indicates that the red shift is not due to effect of solvent polarity but due to existence of weak electronic interaction acting directly between BR and CH2Br2. The nonlinear dependence of decay rates of BR upon [CH2Br2] is interpreted in terms of a simple kinetic model of solvation based on solvent replacement between cage and bulk.
Electric and Magnetic Properties of a Neutral Radical, 2-Cyano-10-methyl-5 -phenazinyl
Authors: Awaga Kunio , Sugano Tadashi , Kinoshita Minoru 
Published: July 2006

Abstract
The temperature dependence of electric conductivity, static magnetic susceptibility and ESR absorption, and electronic absorption spectra at room temperature have been measured on an organic neutral radical, 2-cyano-10-methyl-5-phenazinyl (NMPN). NMPN is found to be more conductive than the neutral radicals studied previously. The room temperature conductivity of powder NMPN is of the order of 10−7 Ω−1 cm−1 and the activation energy is 0.36 eV. The absorption spectra and the magnetic susceptibility measurements indicate that the NMPN molecules form pairing array with considerably large interpair interaction in the solid state. The absence of the triplet fine structure in the ESR spectrum also suggests the existence of the interpair interaction. From these, the magnetic behavior of NMPN is interpreted in terms of the alternating antiferromagnetic Heisenberg model with temperature dependent alternation.
Conformation and Coordination Behavior of Zinc(II) Complex with Cyclo(l-methionyl-l-histidyl)
Authors: Kojima Yoshitane , Hirotsu Ken , Yamashita Tetsushi , Miwa Toshio 
Published: July 2006

Abstract
The crystal structure of a zinc(II) complex with cyclo(l-methionyl-l-histidyl) shows that all four ligands coordinated tetrahedrally to a Zn2+ ion have a folded conformation, with the imidazole ring facing the piperazine ring in each ligand. The calculation from α-β coupling constant data (obtained by 1H NMR measurement) of the histidyl residue of cyclo(l-methionyl-l-histidyl) linked to a Zn2+ ion shows that the ratio of a folded conformation to an unfolded one is 61:39 in D2O.
The Facile Synthesis of Dihydrofurans by the Oxidation of Olefins with Tris(2,4-pentanedionato)manganese(III)
Authors: Nishino Hiroshi 
Published: July 2006

Abstract
Eleven olefins were oxidized with tris(2,4-pentanedionato)manganese(III) at the reflux temperature to give the corresponding 3-acetyl-2-methyl-4,5-dihydrofurans in good yields. The oxidation of 9-benzylidene-9,10-dihydroanthracene under the same reaction conditions did not produce the corresponding dihydrofuran, but 9-[α-(1-acetyl-2-hydroxy-1-propenyl)benzylidene]-9,10-dihydroanthracene. When 1,1-diphenylethene was oxidized at room temperature, 3-acetyl-2-hydroperoxy-2-methyl-5,5-diphenyltetrahydrofuran was obtained in a high yield. The effects of the solvent and the additives on the yield of dihydrofuran, the comparable reactivities of other (2,4-pentanedionato)metal complexes, such as Co(III), Cr(III), Fe(III), and Cu(II), and the reaction mechanism are discussed.
ESR and ENDOR Studies of Cation Radicals Derived from Benzodipyran Compounds. Structure and Dynamic Behavior of Heterocyclic Ring in Tocopherol (Vitamin E)
Authors: Mukai Kazuo , Uemoto Yuichi , Ishizu Kazuhiko 
Published: July 2006

Abstract
ESR and ENDOR spectra of cation radicals of benzodipyran compounds were measured in CH2Cl2, and the proton hyperfine coupling constants were correctly determined for each radical. From detailed analysis of the temperature dependence of hyperfine coupling of β- and γ-methylene protons in the heterocyclic ring, the equilibrium conformation of the β-methylene group and activation energy for the conformational interconversion have been determined. The structure of the heterocyclic ring was compared with those of α-tocopherol (vitamin E) model previously obtained by X-ray analysis. The result suggests that the solution and crystal conformations of the heterocyclic ring are distinctly different.
A Convenient Route to 2-Lithio-1,3-butadiene from Chloroprene via 2-Stannyl-1,3-butadiene
Authors: Wada Eiji , Kanemasa Shuji , Fujiwara Isamu , Tsuge Otohiko 
Published: July 2006

Abstract
A convenient route to 2-lithio-1,3-butadiene from chloroprene via a 2-stannyl-1,3-butadiene is presented, and the regioselecdve additions to a variety of carbonyl groups are demonstrated.
Restricted Rotation Involving the Tetrahedral Carbon. LVII. Stereodynamics of 9-(2-Alkylphenoxy)-1,4-dimethyltriptycenes
Authors: Yamamoto Gaku , Oki Michinori 
Published: July 2006

Abstract
1,4-Dimethyl-9-phenoxytriptycene and its derivatives carrying a methyl, isopropyl, or t-butyl group in the o-position of the phenoxyl moiety were synthesized and their dynamic NMR behavior was studied. These molecules are considered to constitute a bevel gear system with a two-toothed and a three-toothed wheels and the dynamic NMR behavior is best explained in terms of gear rotation. The o-isopropyl derivative, for example, shows the energy barriers of 17.2 and 10.8 kcal mol−1 for the ap\ightleftharpoons±sc and +sc\ightleftharpoons−sc gearing processes, respectively. The population of the ±sc rotamer increases with the bulkiness of the o-alkyl group: The steric congestion among the o-alkyl group, the oxygen atom, and the peri-methyl group is severer in ap than in ±sc. Results of molecular mechanics calculations on these molecules are discussed.
Hydrogenation of Pyrene and Catalytic Interconversion of Hydropyrenes
Authors: Minabe Masahiro , Nakada Katsuko 
Published: July 2006

Abstract
Reexamination on the hydrogenation of pyrene (1) with Raney nickel catalyst under atmospheric pressure afforded a mixture of 4,5-di- (2), 4,5,9,10-tetra- (3), 1,2,3,6,7,8-hexa- (4), and 1,2,3,3a,4,5-hexahydropyrene (5). The relative amount of each product at the initial reaction stage was determined by time–yield relation of the products. The formation sequence of the products is discussed with reference to the hydrogenations of 2–5: 4 may be formed independent of 2, and 2 is converted to 3. Hydropyrene 5 may be produced from 1 mainly through the same σ-adsorbed species which also leads to 2. The hydrogenation of 1 with palladium and platinum catalysts gave similar results as with nickel. With nickel and palladium catalysts the hydrogenation of 1 was faster than that of 4H-cyclopenta[def]phenanthrene (9). However, with platinum the hydrogenation of 1 was slower than that of 9. Catalytic interconversion of 2–5 was examined at 240 °C under an argon pressure of 90 kg cm−2. Hydroarene 2 was easily dehydrogenated, and 3 and 5 were interconverted to a fair extent. Therefore, 2, 3, and 5 may be good hydrogen donor solvents for coal liquefaction.
Rotational Isomerism in Fluorene Derivatives. IX. Restricted Rotation about the C(9)–C(9′) Bonds in 9(or 9′)-Substituted2-Methyl-9,9′-bifluorenyls
Authors: Kajigaeshi Shoji , Nishida Akiko , Fujisaki Shizuo 
Published: July 2006

Abstract
Several 9(or 9′)-substituted 2-methyl-9,9′-bifluorenyls were prepared and the restricted rotation about the Csp3–Csp3 bonds in these compounds were investigated by DNMR. In these cases, nonequivalent gauche conformers were observed at low temperatures. Barriers (ΔG\eweq) for the forward and backward interconversions were slightly increased in agreement with the bulkiness of the 9(or 9′)-substitutents.
α,β-Epoxy Sulfoxides as Useful Intermediates in Organic Synthesis. I. A Novel Synthesis of Dialkyl Ketones and a Synthesis of Aldehydes from Ketones by One Carbon Elongation
Authors: Satoh Tsuyoshi , Kaneko Youhei , Izawa Takao , Sakata Kiichi , Yamakawa Koji 
Published: July 2006

Abstract
Treatment of α,β-epoxy sulfoxides, prepared from 1-chloroalkyl phenyl sulfoxides with ketones or aldehydes, with sodium benzeneselenolate gives dialkyl ketones or aldehydes in good yields under mild conditions. The mechanism of this reaction and an application of this process to a formal total synthesis of dihydrojasmone are described.
Vibrational Analysis of Tangled Spectra. I. The Crystal Phase T←S Spectra of Acetophenone
Authors: Nakashima Kenichi , Koyanagi Motohiko 
Published: July 2006

Abstract
The T1,2←S0 phorescence excitation spectrum of acetophenone has been observed in a crystal at 4.2 K. The observed tangled vibronic structure is a manifestation that two states of different orbital types, 3ππ* and 3nπ*, lie close to each other. For the first time, the spectrum has been vibrationally analyzed in terms of the crude adiabatic Born-Oppenheimer vibronic states. The calculation is advanced via the following steps: (1) to assume appropriate zero-order vibronic level functions of both electronic excited states in the energy region 0–1000 cm−1 above the T1 phosphorescent origin level, (2) to take into account two different perturbations of vibronic and environmental interactions, (3) to establish a secular equation with two adjustable parameters for the evaluation of the off-diagonal matrix elements, (4) to diagonalize the equation after allocating appropriate values to the parameters, (5) to simulate the T←S spectrum, (6) to compare the simulation spectrum with the observed, (7) to revise several diagonal elements and the parameters if the comparison is not satisfied, and (8) to proceed with steps (1)–(7) until the simulation spectra accord with the observed. The results establish that the lowest excited triplet state of acetophenone in the crystal is ππ*, and that the next one is nπ* whose zero-order vibrationless level is postulated to lie at ≈400 cm−1 higher than T10(0).
Adsorption of Phenol on Surface-modified Carbon Black from Its Aqueous Solution. II. Influence of Surface-chemical Structure of Carbon on Adsorption of Phenol
Authors: Asakawa Takeo , Ogino Keizo , Yamabe Kiyoshi 
Published: July 2006

Abstract
Samples of electronic conductive carbon black (Lion Akzo Co.) were treated with nitric acid, hydrogen peroxide, dried air, or hydrogen gas. These samples had almost the same specific surface areas and pore volumes, except for the one treated with nitric acid. Phenol gas adsorption and aqueous-phase adsorption were carried out in order to study the adsorption mechanism on these treated samples. During aqueous-phase adsorption, the amount of phenol adsorbed increased with a decrease in the number of surface oxygen compounds on the carbon sample. During gas adsorption, the amount of phenol adsorbed decreased with a decrease in the number of oxygen compounds on the carbon surface. The residual amount of phenol also decreased. In the case of gas adsorption, interactions occur not only between the hydrophobic sites on the carbon and the hydrophobic groups of phenol, but also between the surface functional groups on the carbon and the hydrophilic groups of phenol. In the case of aqueous-phase adsorption, competitive adsorption of phenol with water molecules occurs. Water molecules adsorb, selectively, the surface functional groups on the carbon. Thus, the phenol adsorption due to the hydrophobic interaction on the carbon interferes with this selective adsorption.
Photoinduced Reduction of Methylviologen by Ascorbate Using Chlorophyllin in Liposome System
Authors: Hidaka Seiji , Matsumoto Eizo , Toda Fujio 
Published: July 2006

Abstract
Photoindeced electron transport across bilayer lipid membrane was studied, using chlorophyllin (Chln), a water-soluble derivative of chlorophyll. Photoreduction of methylviologen (MV2+) by ascorbate was observed only in the liposome system containing ascorbate in the internal aqueous phase and MV2+ in the external aqueous phase. This suggests asymmetry of bilayer lipid membrane. This reaction rate was not affected by the addition of carbonyl cyanide m-chlorophenylhydrazone in the system buffered by tris(hydroxymethyl)aminomethane (Tris), but strongly affected by N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid. In the system buffered by Tris, a proton carrier is not Chin having carboxyl groups but Tris possessing primary amine group. Replacement of the central Mg of Chin with Zn gives a higher rate of MV2+ photoreduction, but when Cu was used in place of Zn, photoreduction was not observed. The central metal may affect the redox potential and the life time of excited Chln.
The Thermal Addition Reactions of Cycloheptatriene with Aromatic p-Quinones
Authors: Mori Akira , Mametsuka Hiroaki , Takeshita Hitoshi 
Published: July 2006

Abstract
Thermal addition reactions of cycloheptatriene with several aromatic p-quinones gave the Diels-Alder adducts as minor products; the most characteristic feature was the formation of the vic-ditropylation products. The mechanism of their formation was clarified to be a sequential ene-reaction and dehydrogenation by means of chemical conversion from the isolated intermediates. Several new other additions, e.g., successive Diels-Alder reactions, were also noted.