bluuebunny/crossref_metadata_2025_split huggingface dataset:
Restricted Rotation Involving the Tetrahedral Carbon. XXXV. Stereodynamics of 9-(3,5-Dimethylbenzyl)triptycene Derivatives
Authors: Yamamoto Gaku , Oki Michinori 
Published: July 2006

Abstract
Stereodynamics of a variety of 9-(3,5-dimethylbenzyl)triptycene derivatives was studied. Atropisomerism about the bridgehead-to-methylene bond was realized in a triply peri-substituted derivative, 8,13-dichloro-1,4-dimethyl-9-(3,5-dimethylbenzy)triptycene: the activation enthalpy for the ap→±sc conversion was 26.4 kcal/mol. Barriers to rotation about the bridgehead-to-methylene bond in a variety of triply, doubly, and singly peri-substituted derivatives were obtained by DNMR method. DNMR behavior of the diastereotopic m-methyl groups in the benzyl moiety revealed the dual mechanisms of the methyl exchange process: rotation about the methylene-to-aryl bond by 180° without rotation about the bridgehead-to-methylene bond (“isolated rotation (IR)”) and rotation about the methylene-to-aryl bond by 180° synchronous with rotation about the bridgehead-to-methylene bond by 120° (“gear motion (GM)”). The GM process predominates in peri-unsubstituted derivatives, while the IR process predominates in triply peri-substituted ones.
The Crystal and Molecular Structure of Grayanotoxin XVI Hemihydrate
Authors: Furusaki Akio , Gasa Shinsei , Ikeda Ry\={u}z\={o} , Matsumoto Takeshi 
Published: July 2006

Abstract
The molecular structure of grayanotoxin XVI, C22H34O6, has been confirmed by means of an X-ray crystal analysis of its hemihydrate. The crystals are orthorhombic, with eight formula units in a unit cell with dimensions of a=17.503, b=37.933, and c=6.371 Å; the space group is P212121. 4180 unique intensity data were collected on a four-circle diffractometer with LiF-monochromated Cu Kα radiation. The structure was solved by the Monte Carlo direct method, using the 30 strongest reflections as the starting set, and was refined by the block-diagonal least-squares method. The final R value was 5.5%. The present analysis has revealed that the crystal used comprises about four parts of grayanotoxin XVI (6-O-acetylgrayanotoxin II) and one part of 10,20-dihydrograyanotoxin XVI. The molecules of the major component exist in two different conformations: One has the chair B-ring, and the other the twist-chair B-ring. About two-fifths of the molecules of the latter type are replaced at random by the molecules of the minor component.
Branched-chain Sugars. XXI. Synthesis of New Branched-chain Cyclitols Having neo-, myo-, and chiro-Configurations from 3-O-Benzyl-5,6-dideoxy-5-C-(1,3-dithian-2-yl)-6-nitro-d-galactofuranose and -l-altrofuranose
Authors: Iwakawa Masaharu , Yoshimura Juji , Funabash Masuo 
Published: July 2006

Abstract
The Michael addition of 2-lithio-1,3-dithiane to 3-O-benzyl-5,6-dideoxy-1,2-O-isopropylidene-6-nitro-β-l-arabino-hex-5-enofuranose afforded a 1 : 1.8 mixture of 3-O-benzyl-5,6-dideoxy-5-C-(1,3-dithian-2-yl)-1,2-O-isopropylidene-6-nitro-α-d-galactofuranose and-β-l-altrofuranose. Removal of the isopropylidene group and intra-molecular cyclization under weakly basic conditions afforded a mixture of branched-chain cyclitols having neo-, myo-, and chiro-configuration. A similar cyclization of the O-deisopropylidenated product of 3-O-benzyl-5,6-dideoxy-1,2-O-isopropylidene-6-nitro-5-C-(nitromethyl)-β-l-arabino-hexofuranose also afforded a mixture of cyclitols having neo-, myo-, and chiro-configuration. The results confirm the importance of two bulky groups such as benzyloxy at C-3 and 1,3-dithiane residue at C-5 in determining the stereodirection of cyclization.
Polarographic Studies on Ninhydrin in DMF and Dehydration from gem-Diol Structure
Authors: Ohmori Mitsuaki , Takagi Masanosuke 
Published: July 2006

Abstract
The d.c.-polarogram of ninhydrin (I) in DMF containing 0.1 M TEAP shows three cathodic waves whose E1⁄2 are −0.38, −0.65, and −1.23 V (vs. SCE), respectively. The first wave with a large maximum is attributed to one-electron reduction of 1,2,3-indantrione (II), the hydrated form of I, the second to one-electron reduction of I, and the third to one-electron reduction of the preceding electrochemical product from both I and II. CV Curves of I show three cathodic peaks, pc1, pc2, and pc3, and two anodic peaks, pa1 and pa2, showing reversible character of pc1 and pc3 but not of pc2. Different equilibria seem to take place between I and II in the bulk of the solution and at electrode surface. Hydration of II and dehydration of I in DMF were observed at 550 nm spectroscopically. A scheme is proposed for the electrolytic reduction of I in DMF.
Mechanochemical Reactions at High Pressures. I. The Design and Construction of the Apparatus and Preliminary Experiments
Authors: Ogo Yoshiaki , Nishiguchi Noboru , Okuri Yasuhiro 
Published: July 2006

Abstract
An apparatus for investigating mechanochemical reactions at high pressures of up to 50 kbar and preliminary experiments on acrylamide are described. The essentials of the apparatus are a rotating platen inserted in a Bridgman-type opposed-anvil press. The central platen is rotated by the force of an electric motor or by manual strokes under high pressure. The pressure distribution on the anvil surface was evaluated from the changes in the electric resistances of CdSe and CdTe as calibrants. The pressure observed at the center was 4.5 times the nominal load pressure. The phase-transition pressure of naphthalene was identified as about 25 kbar from the measurement of the pressure effect on the shearing strength. The mechanochemical behavior of acrylamide was investigated at room temperature and at static pressures of up to 15 kbar. The determinations of the IR spectrum, the ESR signal, the X-ray diffraction pattern, and the molecular weight confirmed that the reaction products were amorphous polyacrylamides and that the mechanical shear stress on the conversion of acrylamide to a polymer was exceedingly effective in comparison with static pressure.
The Stability of Spherical Micelles of Dodecyltrimethylammonium Chloride in Aqueous NaCl Solutions
Authors: Ozeki Sumio , Ikeda Shoichi 
Published: July 2006

Abstract
Light scattering from solutions of dodecyltrimethylammonium chloride in water and 4.00 M (1 M=1 mol dm−3) NaCl has been measured at 25 °C, and the critical micelle concentrations and the micellar molecular weights have been determined. The critical micelle concentration, when combined with the previous data, follows the linear Corrin-Harkins equation over the whole range of NaCl concentrations. The micellar molecular weight remains low, i.e., about 20000 even in the presence of 4.00 M NaCl, and the double-logarithmic relation between the micellar molecular weight and the ionic strength is represented by a straight line over the whole range of NaCl concentrations, when plotted together with the previous data. These results indicate that only spherical micelles are formed by dodecyltrimethylammonium chloride in the presence of added NaCl. The stability of the spherical micelle is attributed to the low degree of binding of Cl− on the cationic micelles.
Structure of Mercury Layer Deposited on Platinum and Hydrogen-evolution Reaction at the Mercury-coated Platinum Electrode
Authors: Yoshida Zenko 
Published: July 2006

Abstract
The thermal evaporation of mercury is investigated in order to ascertain the structure of mercury electrodeposited on platinum. At first, Pt2Hg is formed on platinum, and a hydrogen(H)-overpotential at the surface is identical with that at the mercury-free platinum. With the increase in the amount of mercury to more than the amount corresponding to PtHg, the H-overpotential increases. When a large amount of mercury is deposited, the layer is composed of three mercury compounds (Pt2Hg, Pt2Hg2, and PtHg4), metallic mercury, and adatom mercury. Even when a sufficiently large amount of mercury is deposited, e.g., several thousand atomic layers, the H-overpotential is much less than that at a hanging mercury drop electrode (HMDE). From the general relationship between the hydrogen evolution at a metal electrode and the work function of the metal, the change in the H-overpotential with the increase in the amount of mercury is attributable to the work-function change.
Photopolymerization of Methyl Methacrylate Using N,N-Dimethylformamide–Sulfur Dioxide Complex as the Photoinitiator
Authors: Ghosh Premamoy , Biswas Samir , Jana Subhankar 
Published: July 2006

Abstract
Photopolymerization of MMA in visible light was studied at 40 °C using DMF–SO2 complex as the photoinitiator. Initiator exponent was found to be 0.41 and monomer exponent varied between 1.12 to 1.50 depending on the nature of the solvent. Analysis of data revealed that the photopolymerization was induced by a free radical mechanism. Nonideality of the kinetics was explained on the basis of (a) monomer-dependent chain initiation and (b) initiator-dependent chain termination via degradative initiator transfer.
Effect of Halogen Substituents of Anion Radicals on the Electronic States of Crystalline Anion Radical Salts; K+ p-Chloranil\ewdot, K+ 2,5-Dibromo-3,6-dichloro-p-benzoquinone\ewdot, and K+ p-Bromanil\ewdot
Authors: Iida Yôichi 
Published: July 2006

Abstract
The intermolecular interactions in crystalline anion radical salts of K+ p-Chloranil\ewdot, K+ 2,5-Dibromo-3,6-dichloro-p-benzoquinone\ewdot, and K+ p-Bromanil\ewdot were examined in terms of one-dimensional half-occupied Hubbard model. Effect of substituents of the anion radicals on the crystal electronic states was discussed with the parameter values estimated by the Hubbard model.
Polymer-bound “Dimethylaminopyridine” as a Catalyst for Facile Ester Synthesis
Authors: Shinkai Seiji , Tsuji Hifumi , Hara Y\={o}ichiro , Manabe Osamu 
Published: July 2006

Abstract
Polystyrene beads which covalently link a dimethylaminopyridine unit act as a catalyst for ester synthesis by the DCC method. The polystyrene beads are reusable and the synthetic method is very simplified.
Mass Spectral Dehydration and Decarboxylation in Cyclic α-Hydroxy Acids, Alcohols, and Carboxylic Acids
Authors: Akkari Khalid H , Matta Michael S , Patrick Timothy B 
Published: July 2006

Abstract
The relative ease of mass spectral de-carboxylation is greater than the ease of mass spectral dehydration as determined from a comparison of the alcohols 1a–4a with acids 1b–4b. However, the relative ease is reversed in α-hydroxy acids 2c–4c; and dehydration predominates over decarboxylation.
The Concentration Dependence of the Apparent Molal Adiabatic Compressibility of Electrolytes in Water
Authors: Sakurai Masao , Komatsu Tsuyoshi , Nakagawa Tsurutaro 
Published: July 2006

Abstract
The apparent molal adiabatic compressibilities of NaCl, KCl, NaBr, and KBr in water have been measured in the concentration range from 0.01 to 1 mol kg−1 at 5, 25, and 45 °C. The results have been fitted to a Redlichtype equation: φKs=φKs°+SKsc1⁄2+BKsc. The limiting slope, SKs, was found experimentally as 5.6×10−4 at an ordinary temperature. Convenient equations for the conversion of adiabatic to isothermal compressibilities have been derived; the limiting slope for isothermal compressibility, SKT, should be larger than SKs at all the temperatures studied. The value of SKs determined experimentally has been compared with that predicted from the SKT values calculated by Mathieson and Conway, by Millero, and by Bradley and Pitzer.
Thermodynamic Studies of Thallium Halide Formation in Nonaqueous Solvents
Authors: Sasaki Yukio , Takizawa Masao , Umemoto Kisaburo , Matsuura Niro 
Published: July 2006

Abstract
The differences in the order of stability among halide ions for metal halogeno-complexes in nonaqueous solvents and water are examined by means of the thermodynamic constants for the formation of thallium halides of transfer from water to N,N-dimethylformamide (DMF) and propylene carbonate (PC). The thermodynamic constants for the formation of thallium halides were calculated from the solubility products of thallium halides. The differences in the order of stability for thallium halides were found to be dependent mainly on the enthalpy changes for the formation of thallium halides of transfer from water to DMF and PC, while the enthalpy changes of transfer for thallium halides are themselves largely influenced by the enthalpy changes for halide ions of transfer from water to DMF and PC.
Electrode Kinetics of Eu(III) Ion in the Presence of 1,4-Benzenedimethanol
Authors: Ikeda Osamu , Tsuura Katsuhiko , Tamura Hideo 
Published: July 2006

Abstract
In order to know the role of aromatic ring on the electrode kinetics, d. c. polarogram of Eu(III) ion was measured in the presence of 1,4-benzenedimethanol (1,4-BDM). The effect of the adsorption has been discussed by correlating the kinetic data to the adsorption behaviors of 1,4-BDM estimated from the electrocapillary curves. At the standard potential of Eu(III)/Eu(II) (−0.600 V vs. SCE), 1.4-BDM on the electrode changed its orientation from horizontal to vertical with an increase in the coverage. Both orientations showed an inhibition effect for the electroreduction of Eu(III) ion. When the coverage due to the horizontal orientation is less than 0.8, the inhibition was interpreted by an additional energy to deform the surface layer. On the other hand, the inhibition at full coverage due to both the horizontal and the vertical orientations was interpreted by the tunneling probability through the adsorbed layer differed in the thickness.
A Study of the Calcium Oxide–Water Vapor System by Means of the Transpiration Method
Authors: Matsumoto Kazutoshi , Sata Toshiyuki 
Published: July 2006

Abstract
The system of calcium oxide and water vapor was studied using the transpiration method. Under the conditions of a temperature range from 1678 to 2016 K and PH2O values from 1.2×10−2 to 4.7×10−1 atm, the predominant reaction in this system was found to be CaO(s)+H2O(g)=Ca(OH)2(g). The standard Gibbs free energy of the reaction is given by this equation: ΔGr°=(61300±820)−(12.8±0.48)T (cal/mol) in the present temperature range. From the thermochemical cycle, the dissociation energy, D0°(Ca–(OH)2), was estimated to be 206.4 kcal/mol.
Photocurrents in the ZnO and TiO2 Photoelectrochemical Cells Sensitized by Xanthene Dyes and Tetraphenylporphines. Effect of Substitution on the Electron Injection Processes
Authors: Matsumura Michio , Mitsuda Kenro , Yoshizawa Nobuyuki , Tsubomura Hiroshi 
Published: July 2006

Abstract
The photocurrents in zinc oxide and titanium dioxide electrodes sensitized by anionic xanthene dyes (Eosine Y, Phloxine B, Erythrosine, and Rose Bengal) and metal tetraphenylporphines were studied in aqueous solutions. The quantum efficiencies of the photocurrents sensitized by anionic xanthene dyes were unaffected by substitution of the dye with various halogen atoms, while those sensitized by the tetraphenylporphines were affected by changing the central metal. It is concluded from these results that the electron injection from the excited xanthene dyes to the semiconductor electrodes is a process so rapid (&lt;&lt;0.1 ns) that no internal quenching processes can compete with it, while that from the tetraphynelporphines is relatively slow competing with the internal deactivation processes. It is also concluded that the electron back transfer from the semiconductor conduction band to the oxdized dye decreases the sensitization efficiency.
Influence of Chemisorption of 2-Propanethiol on the Electrical Properties of Silver Oxide Compaction
Authors: Yamamoto Naoto , Tonomura Shoichiro , Matsuoka Tsugufumi , Amamiya Takashi , Tsubomura Hiroshi 
Published: July 2006

Abstract
The work function of silver oxide (Ag2O) decreased by as much as 0.8 eV on exposure to 2-propanethiol [(CH3)2CHSH]. The change in work function was irreversible at room temperature, and proportional to the amount of thiol in case where the partial pressure is low, but reversible at 200 °C. The conductivity of the Ag2O disk showed no substantial change by exposure to thiol. From the infrared absorption spectral studies, it was found that the thiol reacted with the silver oxide forming a (CH3)2CH–S–Ag group on the surface. The relationship between the work function and the chemical processes occurirng at the solid surface is discussed.
Recovery of Heavy Metals with Calcium Silicon. I. Its Stability in Water and Reducing Effect on Metal Ions
Authors: Tokunaga Shuzo , Uematsu Kitoshi , Nagawa Yoshinobu 
Published: July 2006

Abstract
The stability of calcium silicon in aqueous solutions was studied by determining dissolution rates of Ca and Si at a constant pH. Calcium silicon was found to be fairly stable in solutions of pH 3.0–8.0, at most less than 2.8%of Ca and 0.5% of Si being dissolved after 24 h. In a strong acid solution of pH 2.5 or less the dissolution rates of Ca and Si considerably increased. Ca dissolution reached a plateau and the whole amount of Ca did not dissolve even in a 3.0-mol dm−3 HCl solution, while Si dissolution continued to increase. Calcium silicon apparently reduces metal ions to the elemental state for metal ions having higher standard electrode potentials than Cd(II) ions except Ni(II) and Co(II) ions. For Ag(I) ions, nitrate ions interfere with the reduction, but chloride ions favor it. Reduction of Cr(VI) and Fe(III) ions terminated at the stage of Cr(III) and Fe(II). Pb(II), Cu(II), and Hg(II) ions were reduced to the metals, the acidity of the solution and the metal ion concentration not affecting the reduction. Calcium silicon is effective also for low-solubility compounds of these elements in suspension.
Alkali Metal Ion Exchange on Crystalline Zirconium Titanium Phosphate
Authors: Tomita Isao , Iwase Kenkichi , Saito Kazuhiko , Sugiyama Yoshiyuki 
Published: July 2006

Abstract
Ion-exchange studies of crystalline zirconium titanium phosphate with variable zirconium-to-titanium mole ratios have been extended to sodium-ion exchange on the exchangers with Zr-to-Ti mole ratios of 0.37 and 0.61, and to lithium and potassium ion exchange on the exchanger with a Zr-to-Ti mole ratio close to unity. In the sodium-ion exchange, a mono-sodium phase formed up to about a half of the exchange; then a disodium phase with a different amount of water of crystallization formed. In the lithium-ion exchange, the reaction proceeded with the formation of fully exchanged phases whose water content varied depending upon the environment in which the exchanger was placed during or after the reaction. The exchange amount of potassium ions was much less than that of sodium or lithium ions, and the ion exchange proceeded in parallel with an extensive hydrolysis of the exchanger. The half-exchanged phase could not be confirmed in this case. For the three alkali metal ions studied, the selectivity series was found as a function of loading, i.e., within the range of the load from 0 to 1.3 meq/g, the selectivity is in the order of Na+&gt;K+&gt;Li+, between 1.3 and 4.5 meq/g, it is Na+&gt;Li+&gt;K+, and above 4.5 meq/g loading, it turns out to be Li+&gt;Na+&gt;K+.
Effect of the Buffering Capacity of a Supporting Solution on Paper Electrophoretic Migrations of Adenine, Adenosine, and Adenosine Nucleotides
Authors: Kitaoka Yoshinori 
Published: July 2006

Abstract
Paper electrophoretic migrations of adenine, adenosine, and adenosine nucleotides as a function of pH-values of various supporting solutions have been studied. The buffering capacity of the supporting solution played an important role in the migration and is discussed along with the electroosmosis. The Rf-values of adenines in the supporting solutions are also presented.
The Addition of (Thioacyloxy)silanes to Carbonyl Compounds
Authors: Horii Toyokazu , Kawamura Shunichi , Nakabayashi Takeshige , Abe Yasuo 
Published: July 2006

Abstract
The reactions of (thioacyloxy)silane (O-trimethylsilyl thioacetate and thiobenzoate) with some aldehydes (propionaldehyde, butylaldehyde, and benzaldehyde) gave S-(1-substituted alkyl) thioacetates (S-[1-(trimethylsilyl-oxy)propyl, and -butyl] thioacetates, and S-[α-(trimethylsilyloxy)benzyl] thioacetate), and the three corresponding thiobenzoates respectively. The reactions were catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU), and also by its salt with thiobenzoic acid.
Formation and Molecular Dynamics of Cycloamylose Inclusion Complexes with Phenylalanine
Authors: Inoue Yoshio , Miyata Yoshiaki 
Published: July 2006

Abstract
The molecular dynamics of the inclusion complexes of cycloamyloses with phenylalanine in aqueous solution at different pD have been studied by means of carbon-13 NMR spectroscopy. As host cycloamyloses we have chosen cyclohexaamylose, cycloheptaamylose, and cyclooctaamylose. The influences of the cavity size of cycloamyloses and of medium pD values on the molecular dynamics of inclusion complexes were studied by using the NT1η values, where T1 is the carbon-13 spin-lattice relaxation time, N the number of directly bonded proton to a given carbon, and η is the viscosity of solution. Upon complexation, the NT1η values of phenyl carbons of guest phenylalanine show larger decreases than those of other carbons, indicating that the guest forms the inclusion complexes with the host by the insertion of its phenyl ring into the host cavity even in the case of cyclooctaamylose. It was found that the strength of the dynamic coupling between host and guest depends on the cavity size and pD values of medium. The strongest coupling was observed for the cycloheptaamylose–phenylalanine system at pD 11.3, where the phenyl ring is deeply and tightly included into the cavity. The inclusion of phenyl ring is shallow and loose in the case of cyclohexaamylose and deep and loose in the case of cyclooctaamylose.
The Photo-Beckmann Rearrangement of Steroidal β,γ-Unsaturated Ketone Oximes
Authors: Suginome Hiroshi , Maeda Norio , Takahashi Yuko , Miyata Nobuyoshi 
Published: July 2006

Abstract
The photoreaction of 4,4-dimethylcholest-5-en-3-one oxime, a β,γ-unsaturated ketone oxime, has given two lactams, 4a,4a-dimethyl-3-aza-A-homocholest-5-en-4-one and 4a,4a-dimethyl-4-aza-A-homocholest-5-en-3-one resulting from photo-Beckmann rearrangement. 4,4,6-Trimethylcholest-5-en-3-one oxime behaved analogously on photolysis, yielding two lactams but accompanied by 4,6-dimethyl-4-methylene-3,4-secocholest-5-ene-3-nitrile as a minor product. In contrast, major products in the ordinary Beckmann rearrangement are nitriles resulting from the second order Beckmann rearrangement.
The Transformation of Jervine into 18-Functional D-Homo-C-norsteroids. IV. The Transformation of Jervine into (20R)-18,20β-Epoxy-3β-hydroxy-17β-ethyletiojervan-18-one 3-Acetate via (20R)-18,20β-Epoxy-3β-hydroxy-12α,17β-ethyletiojervan-11-one 3-Acetate
Authors: Suginome Hiroshi , Ono Hitoshi , Masamune Tadashi 
Published: July 2006

Abstract
Catalytic hydrogenation of (22S,25S)-N-acetyl-3β,23β-dihydroxyveratra-5,13(17)-dien-11-one 3-acetate over rhodium-platinum catalyst in acetic acid gave (22S,25S)-N-acetyl-3β,23β-dihydroxyveratranin-11 -one 3-acetate (2) in ca 70% yield, together with two minor products. Irradiation of 2 in benzene containing mercury(II) oxide and iodine gave 20-formyl-3β-hydroxy-12α,17β-ethyletiojervan-11-one 3-acetate (5) in 43% yield, accompanied by the 17-epimer of (22S,23R,25S)-N-acetyl-3β-hydroxy-5α-jervanin-11-one 3-acetate (4%). Aldehyde 5 was transformed into 3β-hydroxy-12α,17β-ethyletiojervane-11,20-dione 3-acetate (15) (79% yield) by photo- or coppercatalysed oxygenation of the corresponding enamine. Reduction of 15 with sodium borohydride gave 3β,20β-dihydroxy-12α,17β-ethyletiojervan-11-one 3-acetate (17) as a major product (69%), together with the 20-epimer. The hypoiodite reaction of 17 gave 18,20β-epoxy-3β-hydroxy-17β-ethyl-12α-etiojervan-11-one 3-acetate (19) in 92% yield. Hydrolysis of 19 resulted in the isomerization of the C/D ring junction to give 18,20β-epoxy-3β-hydroxy-17β-ethyletiojervan-11 -one (20), the first 18-functional C/D trans D-homo-C-norsteroid ever prepared. Wolff-Kishner reduction of 20 gave the corresponding 11-deoxo compound; its acetylation followed by oxidation yielded 18,20β-epoxy-3β-hydroxy-17β-ethyletiojervan-18-one 3-acetate. The 11-oxo function of 19 can be reduced quite easily with lithium aluminum hydride to give the corresponding 11β-ol.