bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Adsorption of Dodecyldimethylammonium Bromide on Aqueous Surfaces of Sodium Bromide Solutions
Authors: Okuda Hideshi , Ozeki Sumio , Ikeda Shoichi 
Published: July 2006

Abstract
The surface tension of aqueous NaBr solutions of dodecyldimethylammonium bromide has been measured by the drop weight method at different surfactant and NaBr concentrations. By applying the Gibbs adsorption isotherm, surface excess densities of surfactant cation, Na+ and Br− are derived as functions of surfactant concentration at different NaBr concentrations. The rational mean activity coefficients of surfactant and NaBr are both approximated by a common expression satisfying the Brφnsted principle for mixed electrolytes and containing the ionic strength as a variable. Surface excess density of surfactant cation increases with increasing surfactant concentration and has a general tendency still increasing even at the critical micelle concentration. Some comparison of the behavior of surface excess densities of ions between the present bromide system and the previous chloride system is made. The Corrin-Harkins plot for the critical micelle concentration consists of two straight lines intersecting at 0.015 mol dm−3 NaBr.
Asymmetric Hydrogenation of Schiff Base Prepared from α-Keto Ester with Aliphatic Amino Acid Ester
Authors: Harada Kaoru , Shiono Shozo 
Published: July 2006

Abstract
Catalytic hydrogenation of Schiff bases prepared from α-keto esters with amino acid esters was carried out under various conditions. A significant substituent effect of the alkyl group of the ester moiety of amino acid on the stereoselectivity was observed in the hydrogenation of the Schiff bases prepared from methyl pyruvate with (S)-alanine ester. Higher asymmetric yields were obtained as the ester residue of amino acid ester became bulkier. A clear temperature effect on the asymmetric hydrogenation was also observed. These results could be explained by the chelation mechanism.
Synthesis and Properties of the Tristyrylmethyl Anion
Authors: Komatsu Koichi , Shirai Shuzo , Tomioka Isao , Okamoto Kunio 
Published: July 2006

Abstract
The title anion (3) having a C3v symmetric structure was generated from newly synthesized tristyrylmethane (4) and was characterized by means of 1H and 13C NMR spectroscopy. The pKa value of 4 was determined as 20.1 in DMSO–EtOH (9:1), indicating considerable conjugative stabilization of the anion 3. The cyclic voltammetry of 3 in acetonitrile exhibited only irreversible one-electron oxidation peak corresponding to the formation of a chemically unstable radical species. Whereas quenching the anion 3 with H2O or Me3SiCl quantitatively afforded the cross-conjugated triene 6 (R=H or Me3Si), the reaction of 3 with the tropylium ion yielded 1,1′-bicycloheptatrienyl (29%), as well as the triene 6 (R=C7H7) (66%), demonstrating that 3 can also acat as a one electron reductant.
Liquid Crystal Formation in Binary Systems. IX. Effects of Branching of Ester Alkyl Group on the Induction of Liquid Crystals in the Alkyl 4-[4-(Dimethylamino)benzylideneamino]benzoate-4,4′-Dinitroazoxybenzene Systems
Authors: Matsunaga Yoshio , Suzuki Izumi 
Published: July 2006

Abstract
Smectic A liquid crystals are formed not only in systems with normal alkyl esters but also with esters of branched alkyl groups such as t-butyl, 1,2-dimethylpropyl, and 1-ethylpropyl.
X-Ray Structural Elucidation of a Novel Steric Effect of o-Methoxyl Substituents in 2,6-Dimethoxyphenylnickel(II) Complexes Mediated by m-Bromo Substitution
Authors: Xu Duanjun , Kai Yasushi , Miki Kunio , Kasai Nobutami , Nishiwaki Koichi , Wada Masanori 
Published: July 2006

Abstract
Molecular structures of novel trans-[NiR2L2] complexes, trans-[Ni{C6H3(OMe)2-2,6}2(PR3)2] [PR3=PMe3 (1a), PMe2Ph (1b)], and their m-brominated derivatives, trans-[Ni{C6H(OMe)2-2,6-Br2-3,5}2(PR3)2] [PR3=PMe3 (2a), PMe2Ph (2b)], were determined by X-ray crystal structure analysis. A remarkable effect of m-substitution on the conformation of the o-methoxyl groups was found. This correlated well with the reactivity difference toward carbon monoxide. Crystal data: 1a: monoclinic, space group P21/c, a=8.737(2), b=18.282(3), c=16.319(4) Å, β=105.06(2)°, Z=4, R=0.062; 1b: triclinic, space group P\bar1, a=16.993(5), b=10.180(3), c=17.177(5) Å, α=112.44(2), β=117.59(2), γ=66.25(2)°, Z=3, R=0.060; 2a: monoclinic, space group P21/c, a=9.294(2), b=14.091(3), c=10.770(2) Å, β=92.06(3)°, Z=2, R=0.067; 2b: triclinic, space group P\bar1, a=9.370(1), b=11.387(2), c=9.013(1) Å, α=94.52(2), β=107.24(2), γ=77.35(2)°, Z=1, R=0.058.
1,3-Dipolar Cycloaddition Reactions of 6-Methylenetricyclo[3.2.1.02,7]oct-3-en-8-one and Its Related Compounds
Authors: Nitta Makoto , Omata Akihiko , Okada Shuji 
Published: July 2006

Abstract
The cycloaddition reactions of 1,5-dimethyl-6-methylenetricyclo[3.2.1.02,7]oct-3-en-8-one (1a), its corresponding -8-endo-ol (1b), 1,5,8-trimethyltricyclo[3.2.1.02,7]oct-3-en-8-endo-ol (1c), and 5,8-dimethyl-9-methylenetricyclo[3.3.1.02,8]non-3-en-7-one (2) were investigated in order to study the origin of its stereoselectivity or site selectivity. The reaction of 2,4,6-trimethylbenzonitrile oxide (mesitonitrile oxide, MNO) with 1a, b occurs on the exo-mthylene group from the exo-side, but on the endocyclic double bond in the case of 1c. The compound 2 undergoes the addition of MNO on both the exocyclic and endocyclic double bonds to give a corresponding bis-adduct. On the other hand, the reaction of phenyl azide (PA) with 1a–c occurs on the endocyclic double bond from the endo-side to give a single adduct. The reaction of 6-exo-methoxy-1,5,6-trimethyltricyclo[3.2.1.02,7]oct-3-en-8-one with MNO or PA was also studied to prove the regioselectivity of the cycloadditions of constrained vinylcyclopropane moiety.
Water Photolysis by Means of Visible Light with a System Composed of Prussian Blue and the Tris(2,2′-bipyridine)ruthenium(II) Complex
Authors: Kaneko Masao , Takabayashi Naoki , Yamauchi Yukio , Yamada Akira 
Published: July 2006

Abstract
A water-photolysis system composed of Prussian Blue (PB) and the tris(2,2′-bipyridine)ruthenium(II) complex([Ru(bpy)3]2+)which evolves hydrogen and oxygen simultaneously was studied. Both the components worked catalytically in the photolysis. PB provides active sites for both H2 and O2 evolution. The dependence on the pH showed optimum conditions at pH 2. The photolysis required the presence of a cation, and only such cations as K+ and Rb+ whose hydrated ions are smaller than the pore size of the PB lattice were active for the reaction. The dependene on the KCl concentraition showed an optimum point at 0.5 mol dm−3. The oxidative quenching of [Ru(bpy)3]2+* by PB was suggested, but its ratio in the total quenching process was estimated to be only 8.5%. The static quenching of [Ru(bpy)3]2+* by PB was demonstrated, and an interaction between the two components was shown by NMR spectroscopy. The effect of oxygen on the photolysis suggested that the reduction sites are located inside the PB lattice. A mechanism for the photolysis was proposed.
Thermal Behavior of Head-to-head Coumarin Dimers and Their Lactone-opened Derivatives
Authors: Yonezawa Noriyuki , Ikebe Yutaka , Yoshida Tsuyoshi , Hirai Teruhisa , Saigo Kazuhiko , Hasegawa Masaki 
Published: July 2006

Abstract
The thermal behavior of head-to-head coumarin dimers and twelve lactone-opened derivatives was investigated. Though the lactone rings in coumarin dimers are very susceptible to nucleophilic ring-opening, heating these derivatives reformed six-membered lactone rings except for certain imide and diamide derivatives. The large neiboring group effect allowed the relactonization by the attack of hydroxyphenyl group to carbonyl carbon in preference to the scission of cyclobutane ring.
The Thermal Isomerization of Azobenzenes. III. Substituent, Solvent, and Pressure Effects on the Thermal Isomerization of Push-pull Azobenzenes
Authors: Nishimura Norio , Kosako Shinya , Sueishi Yoshimi 
Published: July 2006

Abstract
The substituent, solvent, and pressure effects on the rate of the thermal cis-to-trans isomerization of 4-dimethylamino-4′-nitroazobenzene(NDAAB) derivatives have been studied. 2-Methyl- and 2′-chloro–NDAAB isomerize faster than NDAAB, and 2′-methyl- and 2-chloro-NDAAB isomerize slower than NDAAB. For 2,2′-dimethyl- and 2,2′-dichloro-NDAAB, the rates are between those of the monosubstituted ones. These findings are very similar to those for 4-(dimethylamino)azobenzene (DAAB) derivatives, and no fundamental difference in the kinetic-substituent effects was observed between NDAAB and DAAB. The volume of activation, which is of a negative value, varies remarkably from solvent to solvent and from substituent to substituent; its magnitude increases generally with an increase in the solvent polarity. Even for DAAB and 4,4′-bis(diethylamino)azobenzene (BDEAAB), the rate is appreciably accelerated by external pressures in polar solvents. It is concluded that the observed results are more consistent with the inversion mechanism than with the rotational mechanism.
A Versatile Synthesis of Four-, Five-, and Six-membered Cyclic Ketones Using Methyl Methylthiomethyl Sulfoxide
Authors: Ogura Katsuyuki , Yamashita Mitsuo , Suzuki Michiyo , Furukawa Shigeko , Tsuchihashi Gen-ichi 
Published: July 2006

Abstract
Cyclization of 1,n-dihalo[or bis(tosyloxy)]alkanes with methyl methylthiomethyl sulfoxide in the presence of a base (n-BuLi or KH) gave three-, four-, five-, and six-membered 1-methylsulfinyl-1-methylthiocycloalkanes. These cyclization products were easily converted to the corresponding ketones by acid hydrolysis except 1-methylsulfinyl-1-methylthiocyclopropane which afforded a complicated mixture. The combination of the cyclization with the acid hydrolysis thus provides a new method for synthesizing four-, five-, and six-membered cycloalkanones. Several representative preparations, such as those of substituted cyclobutanones, 3-cyclopentenone, and tetrahydro-4-pyrone, are described.
π-Electron Distribution in Benz[a]indeno[1,2,3-cd]azulene and the Corresponding Azepinium Ion
Authors: Murata Shigeru , Iwamura Hiizu 
Published: July 2006

Abstract
The π-electron density distribution in benz[a]indeno[1,2,3-cd]azulene and the corresponding azepinium ion has been calculated by the PPP MO method. The effects of the hetero atom and the benzo annellation on the π-electron density and bond order of the cyclopent[cd]azulene are discussed.
Excited-state Reactions of Coumarins in Aqueous Solutions. II. The Fluorescence Quenching of 7-Ethoxycoumarins by Halide Ions
Authors: Moriya Tetsuo 
Published: July 2006

Abstract
The fluorescence yield and the fluorescence lifetime of 7-ethoxycoumarins in aqueous solutions are reduced with the increase in the temperature and in the concentration of the quenching agents. The radiationless deactivation of the excited state in the absence of quenchers is temperature-dependent; its activation energy has been determined to be 32.5–34.8 kJ mol−1. The quenching reaction due to halide ions proceeds via both a diffusional and a static process. The rate constant for the diffusional process has a value of (9.7–10.2)×109 mol−1 dm3s−1 in the case of I− as a quencher. The static quenching component can be approximately described by the V[Q] expression, with the static quenching constant, V, being 1.6–1.8 mol−1 dm3. The quenching efficiencies that represent the probability leading to real quenching reactions by an encounter of the molecule and the halide ion are unity for I−, 0.39–0.42 for Br−, and almost zero for Cl−. The possible physical interpretation of the quenching mechanism is discussed in relation to the electron transfer between colliding species.
Carbon-13 Nuclear Magnetic Relaxation Studies of Benzene Molecules Adsorbed on the Pillar Interlayered Montmorillonite
Authors: Matsumoto Mutsuyoshi , Shinoda Sumio , Takahashi Hiroshi , Saito Yasukazu 
Published: July 2006

Abstract
Carbon-13 nuclear magnetic relaxation times of 13C-enriched benzene have been determined in order to elucidate the adsorption properties of PILM (pillar interlayered montmorillonite) by varying temperatures and coverages. The activation energy of diffusion as small as 6.5 kJ mol−1 indicates that the majority of PILM adsorption sites exhibits a weak interaction with benzene. The pre-exponential factor of correlation time was exceptionally large, probably because the two-dimensional pore structure of PILM, in contrast to the three-dimentional zeolite or the open surfaces of graphitized carbon black and silica gel, restricts the chance for the adsorbate to diffuse. In the spin-lattice relaxation spectra at low temperatures, the internal and the external surfaces of PILM were discriminated, since the two adsorbed states on these surfaces give different T1 and chemical shift values.
Comparison of the Experimental Zone Mobility-pH Curves of the Bases of Nucleic Acid on the Pure Cellulose Paper with the Calculated Ones
Authors: Kitaoka Yoshinori 
Published: July 2006

Abstract
Comparison of the experimental zone mobility-pH curves of nucleic acid bases with the calculated ones was made over acidic and basic regions using a pure cellulose paper as a support after correction of the capillary action and the endoosmotic flow. The mobilities in the acid region agreed with the calculated ones but those in the basic region did not. Some unknown factors affect the mobilities in the basic region.
Restricted Rotation Involving the Tetrahedral Carbon. LIV. The Effects of 1-Substituents on the Barriers to Rotation in 9-(2-Methyl-1-naphthyl)fluorenes
Authors: Murata Shigeru , Mori Teruo , Oki Michinori 
Published: July 2006

Abstract
A series of 1-substituted 9-(2-methyl-1-naphthyl)fluorenes, where the substituent is fluoro, chloro, bromo, or methyl, has been prepared and barriers to rotation in these compounds have been examined to investigate the substituent effects. The barrier is enhanced generally, if we go from the 1-substituent of a small size to that of a large size with an exception of the fluorine case: the 1-fluoro compound exhibits a lower barrier to rotation than the unsubstituted compound by ca. 0.5 kcal mol−1. X-Ray crystallographic analysis suggests that, in the fluoro compound, the C9(fluorene)-to-C1(naphthalene) bond is abnormally long, although other compounds possess bonds of normal lengths. The low barrier to rotation in the fluoro compound relative to the unsubstituted is thus attributed to the raise of the ground state energy and insufficient raise of the transition state energy in the former compound.
Crystal and Molecular Structure of 3,8-Di-t-butyl-5,6-diphenyl-1-thioxo-2,9-dithia-1-phosphabicyclo[4.3.0]nona-3,7-diene
Authors: Uchida Tokiko , Kozawa Kozo , Saito Takao , Motoki Shinichi 
Published: July 2006

Abstract
The crystal and molecular structures of the title compound were determined by means of X-ray diffraction. Crystal data: C26H31S3P, Mr=470.68, orthorhombic, a=17.116(4), b=19.798(4), c=14.898(3) Å, V=5048.4 Å3 (21 °C), space group Pbca, Dm=1.23, Dx=1.239 g cm−3, Z=8, μ=3.58 cm−1 (Mo Kα). The structure was solved by the direct method and refined by the full-matrix least-squares method to R=0.083 for 3318 observed reflections. The bicyclo skeleton is so highly strained that abnormal bond distances [P–C of 1.895(5) and C–C of 1.594(6) Å] were observed. Conformation of six-membered ring is a boat-form.
Shinjulactones G and H, New Bitter Principles of Ailanthus altissima Swingle
Authors: Ishibashi Masami , Yoshimura Shin , Tsuyuki Takahiko , Takahashi Takeyoshi , Matsushita Kazuhiro 
Published: July 2006

Abstract
Two bitter quassinoids, shinjulactones G and H were isolated from Ailanthus altissima Swingle and their structures were determined to be 1β,11β,12α,20-tetrahydroxypicras-3-ene-2,16-dione and 2α,12β-dihydroxypicrasane-1,11,16-trione, respectively, by spectral and chemical means.
Interionic Charge Transfer Enhanced by Hydrophobic Interaction
Authors: Hirano Koichi , Tokuhara Masahiko 
Published: July 2006

Abstract
A water solution containing Rhodamine 6G and Na-tetraphenylborate exhbits a new absorption band at 540 nm, which has the characteristics of a charge-transfer (CT) band. In organic solvents, however, such a CT band is not found. This indicates that hydrophobic interactions enhance the charge transfer interaction.
Dependence of Efficiency of Photoinduced Electron Transfer from Pyrene to Copper(II) Ion on Copper(II)-Ion Fraction on Dodecyl-Sulfate-Micelle Surface
Authors: Nakamura Takashi , Kira Akira , Imamura Masashi 
Published: July 2006

Abstract
In quenching of the pyrene fluorescence by copper(II) ions in dodecyl sulfate micelles whose surface is covered by sodium and copper(II) ions, the pyrene-cation quantum yield decreases, after reaching a certain maximum yield, with increasing copper(II)-ion fraction. The decrease suggests that the micellar structure becomes unfavorable for electron transfer quenching as copper(II) ions displace sodium ions on the micellar surface.
Adsorption Measurements during Catalytic Isomerization of Pentenes and 2-Methyl-1-pentene over KC24
Authors: Tsuchiya Susumu , Yamamoto Shinji , Imamura Hayao 
Published: July 2006

Abstract
The catalytic isomerization of pentenes over KC24 has been investigated. The double-bond-migration and the cis-trans isomerization took place over KC24, but the skeletal isomerization was not observed. From the rates of reactions and the selectivity ratios, all six of the relative rate constants and the activation energies of reactions were determined. The reaction paths on the triangular graph calculated from the rate constants show the cis-convex type profile. The competitive isomerization of 1-pentene and 2-methyl-1-pentene has also been investigated. The rate of isomerization of 1-pentene was greater than that of 2-methyl-1-pentene, which can be explained on the basis that the amount of chemisorption of 1-pentene during the competitive reaction is greater than that of 2-methyl-1-pentene.
The Oxidation of Iron(II) Sulfate with Sulfur Dioxide and Oxygen Mixtures
Authors: Sato Tsugio , Goto Takashi , Okabe Taijiro , Lawson Frank 
Published: July 2006

Abstract
The oxidation of iron(II) sulfate with SO2/O2 (sulfur dioxide and oxygen mixtures) was carried out using an air-lift percolator in the temperature range of 25–50 °C and over the pH range of 0–3. Under conditions in which sulfur dioxide is immediately oxidized, the rate of the oxidation of iron(II) is proportional to the flow rate of sulfur dioxide and independent of the flow rate and partial pressure of oxygen, and the concentration of iron(II). The molar ratio of Fe2+ oxidized/SO2 oxidized is 1.3–2 in the pH range of 0.5–2.0. A free-radical chain reaction in which HSO5− oxidizes iron(II) is proposed as the reaction mechanism.
The Synthesis and Thermal Decomposition of Magnesium Phosphoramidate
Authors: Watanabe Makoto , Morii Yoshio , Sato Shoji 
Published: July 2006

Abstract
Magnesium phosphoramidate–water (1/7) was made by adding an aqueous magnesium chloride solution to an aqueous potassium hydrogenphosphoramidate solution at pH 9.0–9.5. The product was stable at room temperature, while it decomposed on heating. The product decomposed to produce polyphosphates when it was heated in air. The decomposition product heated above 600 °C was magnesium diphosphate. A small amount of imidodiphosphate was made when the phosphoramidate was heated in dried N2.
Photochemistry of Dihalogenobis(diamine)chromium(III) Complexes in Methanol
Authors: Sawano Masanori , Yoshifuji Hideki , Uehara Akira , Tsuchiya Ryokichi 
Published: July 2006

Abstract
The photochemical reactions of trans- and cis-[CrX2(AA)2]X in methanol were investigated under the ligand-field band irradiation, where X is Cl− or Br− ion and AA is en, pn or tn. In the earlier step of irradiation, only trans-to-cis photoisomerization was observed irrespective of diamines. The process of the photoisomerization was reasonably explained in terms of the bond indices calculated on the basis of VC theory. The quantum yields for dichloro complexes were larger than those for dibromo complexes, and the yields increased in the order of pn&lt;en&lt;tn complexes. The photochemistry of cis-[CrCl2(pn)2]Cl was also studied and the difference of the photochemical reactions from the thermochemical reactions was discussed.
The Changes in Conformation and Complexability of 6,6′-Diamino-2,2′-bipyridine by Protonation
Authors: Kishii Noriyuki , Araki Koji , Shiraishi Shinsaku 
Published: July 2006

Abstract
The reaction of 6,6′-dibromo-2,2′-bipyridine with ammonia in an autoclave gave 6,6′-diamino-2,2′-bipyridine (DABP) in more than 80% yields. DABP behaved as a diacidic base in the pH range of 0 to 10 with the conformational changes. DABP formed complexes with Cu(II), Ni(II), Co(II), and Zn(II). The amino groups at 6 and 6′ positions play a role as strong electron-donationg groups and not as coordination sites. pKa values and complex formation constants were estimated.
The Reaction of Butadienylphosphonates with a Oxosulfonium Ylide, Phosphonium Ylides, and Ketone Enolates
Authors: Minami Toru , Yamanouchi Takenobu , Tokumasu Shigehumi , Hirao Ichiro 
Published: July 2006

Abstract
The condensation of diethyl (ethoxycarbonylmethyl)phosphonate (1a) with cinnamaldehyde in the presence of piperidine gave a 1:1 mixture of diethyl (1E,3E)- (2a) and (1Z,3E)-(1-ethoxycarbonyl-4-phenyl-1,3-butadienyl)phosphonates (2b) in 82% yield, while a similar reaction using diethyl [cyanomethyl- (1b) and methylsulfonylmethyljphosphonates (1c) exclusively gave diethyl (1E,3E)-[1-cyano- (3) and 1-methyl-sulfonyl-4-phenyl-1,3-butadienyl]phosphonates (4) in 78% and 93% yields, respectively. The reaction of the butadienylphosphonates 2–4 with dimethyloxosulfonium methylide (5) gave mixtures of (E)- and (Z)-(1-substituted 2-styrylcyclopropyl)phosphonates 7–9 in good yields. Similar treatment of the butadienylphosphonate 2 with phosphonium ylides 16a–c led to (3-substituted 1-ethoxycarbonyl-2-styrylcyclopropyl)phosphonates 17a–c in moderate yields. Reduction and oxidation of 7 were studied. The reaction of the phosphonates, 2 and 4, with ketone enolates and ketones resulted in the formation of unexpected olefins 22–24 and dienes 20a, b. The reaction mechanism is discussed.
Redox-Switched Crown Ethers. 1. Redox-Coupled Control of Metal-Ionophore Interactions and Their Application to Membrane Transport
Authors: Shinkai Seiji , Inuzuka Kenichi , Hara Kenzo , Sone Takaaki , Manabe Osamu 
Published: July 2006

Abstract
Polyether ionophores with redox-functional thiol groups were synthesized: they are a diaza-18-crown-6 with a disulfide cap that exhibits redox-responsive interconversion between crown(1red) and cryptand(1ox) and tri- and tetra(oxyethylene)s having a mercapto and an 8-quinolyl group as their terminal groups that feature redox-responsive interconversion between monopodands (2red) and dipodands (2ox). For Na+ 1red and 1ox showed a similar ion affinity, but 1ox bound K+, Rb+, and Cs+ more efficiently than 1red because of the coordination of the cap oxygens to the complexed metal cations. The difference was rationalized by such that “K+ Rb+ and Cs+ also) perches on the crown ring whereas Na+ nests in it,” 2ox showed, in most cases, the ion affinity significantly higher than corresponding 2red, indicating the cooperative action of the two poly(oxyethylene) chains on the ion-binding. The rate of K+ transport with 2red across a liquid membrane was very slow but 2ox carried K+ more efficiently. It was found that the rate of K+ transport started with is efficiently accelerated by the addition of I2. This is due to the redox-switch of the carrier from 2red to 2ox. These results suggest that the redox-functionalized ionophores provide novel applications of ion-extraction and ion-transport.