bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Stability of Substituted Pyridine Adducts of Bis(acetylacetonato)oxovanadium(IV) in Solid State
Authors: Shibutani Yasuhiko , Shinra Koichiro 
Published: July 2006

Abstract
The kinetic of the elimination reaction of axial ligand B in [VO(acac)2B] complexes (Hacac=acetylacetone; B=pyridine, its derivatives, and ammonia) was studied in solid state by the Coats–Redfern method. The frequency factor and activation energy were determined, from which the activation free energy (ΔG\eweq) was calculated. The ΔG\eweq values varied with the nature of pyridine derivatives in the range of 99–109 kJ mol−1. The insight into ΔG\eweq values suggests that the kinetic stability of vanadium-substituted pyridine bond is influenced by both the basicity (pKa) and heat of sublimation (ΔH(sub)) of the axial ligand. Furthermore, the E′ values which appear to reflect coordination ability of base B were determined by reflectance spectra of the complexes. The E′ value was found to increase linearly with the increase in pKa and ΔH(sub) of the axial ligand.
Flow Chemiluminescent Determination of Catecholamines Based on Permanganate Oxidation
Authors: Ikkai Harumi , Nakagama Tatsuro , Yamada Masaaki , Hobo Toshiyuki 
Published: July 2006

Abstract
Luminous oxidation with acidic permanganate was found to be usable for chemiluminescent determination of catecholamines and other polyhydroxybenzenes at picomol levels. The sensitivity is high enough to determine catecholamines in urine. The present CL method is expected to be applicable to the post-column detection of these compounds in high-performance liquid chromatography.
Orientation of Isomeric Phthalic Acids on Alumina and Magnesia Surface Observed by Inelastic Electron Tunneling Spectroscopy
Authors: Higo Morihide , Mizutaru Sinichi , Kamata Satsuo 
Published: July 2006

Abstract
The vibrational spectra of phthalic, isophthalic, and terephthalic acid adsorbed onto alumina and magnesia surfaces from the gas phase have been measured by inelastic electron tunneling spectroscopy. The analysis of the tunneling spectra shows that phthalic and isophthalic acid react with the surface OH groups on Al2O3 and MgO to give the adsorbed dicarboxylate ions on both surfaces. Phthalic acid is adsorbed with its benzene ring perpendicular to the surfaces, while isophthalic acid is adsorbed parallel to the surfaces. However, terephthalic acid is adsorbed predominantly as the monocarboxylate ion almost perpendicular to the alumina surface, while it is adsorbed as the dicarboxylate ion parallel to the magnesia surface. These results suggest the different properties of the surface OH groups on Al2O3 and MgO. There are more than one type of OH group on the alumina surface and they interact with each other through hydrogen bonding. The magnesia surface has an isolated and a hydrogen-bonding OH group. The OH groups on MgO are more basic than those on Al2O3, and thus have higher reactivity. The different properties and basicity of the OH groups cause the different orientation and reactivity of the adsorbed terephthalic acid on the alumina and magnesia surfaces.
A Mechanistic Study on the Reaction of Iminothiadiazolines with Activated Acetylenes: Competitive Pathway through Hypervalent Sulfurane and Zwitterion
Authors: Yamamoto Yohsuke , Tsuchiya Tohru , Ochiumi Masahide , Arai Shin-ichi , Inamoto Naoki , Akiba Kin-ya 
Published: July 2006

Abstract
The reaction of 3-aryl-5-benzoyl-2-imino-2,3-dihydro-1,3,4-thiadiazoles (6) with dimethyl acetylenedicarboxylate (4b) gave the corresponding thiazole (8) and benzoyl cyanide through sulfurane (B) by 1,3-dipolar cycloaddition and cis- (9) and trans-vinyl (10) compounds through zwitterion (C) by simple addition. Two types of addition reactions competed each other and the ratio of the two [R=B/C] depended solely on the solvent polarity (ET). Dibenzoylacetylene behaved similarly. Several iminothiazolines and iminothiadiazolines reacted with activated acetylenes and the selectivity for the two types of addition reactions for each system was shown to be affected by quite subtle balance of electron-withdrawing ability of each heterocycle.
Syntheses of Fluoroalkyl and Fluoroaryl Titanates
Authors: Yoshino Norio , Tomita Junko , Hirai Hidefumi 
Published: July 2006

Abstract
Tetrakis(1H,1H-perfluoroethyl) titanate, Ti(OCH2CF3)4, tetrakis(1H,1H-perfluoropropyl) titanate, Ti(OCH2CF2CF3)4, tetrakis(2,2,2-trifluoro-1-methylethyl) titanate, Ti[OCH(CH3)CF3]4, tetrakis(2,2,2-trifluoro-1,1-dimethylethyl) titanate, Ti[OC(CH3)2CF3]4, tetrakis((1H,1H,3H-perfluoropropyl) titanate, Ti(OCH2CF2CF2H)4, tetrakis(1H,1H,5H-perfluoropentyl) titanate, Ti[OCH2(CF2CF2)2H]4, tetrakis(1H,1H,7H-perfluoroheptyl) titanate, Ti[OCH2(CF2CF2)3H]4, and tetrakis(1H,1H,9H-perfluorononyl) titanate, Ti[OCH2(CF2CF2)4H]4, were prepared by the reaction of titanium tetrachloride with fluoro-substituted alcohols in the presence of ammonia. Tetrakis(pentafluorophenyl) titanate, Ti(OC6F5)4 was synthesized by the ester interchange reaction of tetraisopropyl titanate with pentafluorophenyl acetate. These compounds were characterized on the basis of chemical analysis, IR, 1H NMR, 13C NMR and 19F NMR spectra. Tetrakis(2,2,2-trifluoro-1,1-dimethylethyl) titanate was the monomeric in nitrobenzene, but tetrakis(1H,1H-perfluoroethyl) titanate and tetrakis(1H,1H-perfluoropropyl) titanate were associated in the same solvent, in which the highest association numbers observed were 3.5 and 1.5, respectively. These titanates were very sensitive to moisture and easy to decompose to give titanium oxide and alcohol or phenol.
Mercury-Photosensitized Decomposition of β-Butyrolactone
Authors: Yamamoto Shunzo , Gohda Rinko , Sueishi Yoshimi , Nishimura Norio 
Published: July 2006

Abstract
The mercury-photosensitized decomposition of β-butyrolactone has been investigated at temperatures between 353 and 393 K and pressures from 450 to 13600 Pa. The products were carbon dioxide, propylene, carbon monoxide, propylene oxide, acetone, and acetaldehyde. The yields of these products increased linearly with reaction time and light internsity, while they were independent of the lactone pressure. Three decomposition processes were proposed to explain the formation of the products. The decrease in the quantum yields of carbon dioxide, carbon monoxide, and acetaldehyde observed in the presence of cis-2-butene can be explained by the competitive quenching of the triplet mercury atom by the lactone and cis-2-butene (the quenching efficiency of lactone relative to that of cis-2-butene was estimated to be 0.61). The decrease in the quantum yields of carbon dioxide, propylene, and acetaldehyde by the addition of oxygen can again be explained only by the competitive quenching of the triplet mercury atoms by lactone and oxygen (kQ(lactone)/kQ(oxygen)=1.36). The quantum yields of propylene oxide and acetone, however, decrease more rapidly than predicted for competitive quenching. This indicates the existence of a reaction between oxygen and a biradical, which is a precursor of propylene oxide and acetone.
Dielectric Relaxation and Intermolecular Association for 1-Decanol. Temperature and Dilution Dependences of Monomer and Three Hydrogen-Bonded Species
Authors: Shinomiya Toshiomi 
Published: July 2006

Abstract
The dielectric constants and losses have been measured at frequencies from 1.35 to 4500 MHz for pure 1-decanol at 15–40 °C and for cyclohexane and heptane solutions of 1-decanol at 25°C. The absorption has been resolved into three different Debye-like dispersion regions. The assignments of the three regions were made as follows: the first region being due to a linear hydrogen-bonded chain polymer (C1), the second one to a chain dimer and trimer (C2), and the third one to a free monomer (C3). Four concentrations of these species (C1−3) and a nonpolar cyclic polymer (CR) were evaluated by applying a modified Kirkwood–Fröhlich equation to each dispersion region. Each of the four concentrations indicates a reasonable behavior regarding the temperature and dilution dependences. The C1 decreases and, mainly, the C3 increases as the temperature increases. For cyclohexane and heptane solutions, the C1 decreases rapidly and the CR increases correspondingly with decreasing alcohol concentration. The free energies of activation are 23.2 for the first region, 17.3 for the second region, and 11.9 kJ mol−1 for the third region.
Enhanced Cyclization of N-Benzyloxycarbonyl-N-substituted Dipeptide Methyl Esters with Ammonia
Authors: Kawashiro Katsuhiro , Nishiguchi Kazuhisa , Kurosaka Ikuo 
Published: July 2006

Abstract
Cyclization of N,N′-[N-(benzyloxycarbonyl) (Z)-iminobis(methylenecarbonyl)]bis[glycine] dimethyl ester to the hydantoin derivative took place easily under mild ammonolysis conditions. Replacement of Z by p-methoxy-benzyloxycarbonyl also led to the cyclization. Influence of different substituent groups on the cyclization was studied with some N-Z-dipeptide methyl esters.
CIDEP Study of the Photoreduction of Aromatic Ketones with Alkoxides in Alcohols
Authors: Ohara Keishi , Murai Hisao , Kuwata Keiji 
Published: July 2006

Abstract
The photoreductions of xanthone and benzophenone with alkoxides in several alcohols were studied by observing CIDEP. The total emission spectra, observed after the photoexcitation, were assigned to the ketone anion radicals having TM spin polarization. The dependence of the spectral line width upon alkoxides indicates the existence of a hyperfine interaction between the ketone anion radical and the alkali metal cation, even in the early stage of the photochemical reaction in an alcoholic media. A careful analysis of the spectral pattern leads to the conclusion that the counter radical of the ketone anion interacting as a geminate pair which is responsible for the RPM polarization, is other than a methoxyl radical in these systems.
Shock Tube Studies of the H2–O2 Reaction by Atomic Resonance Absorption Spectroscopy
Authors: Koike Tohru 
Published: July 2006

Abstract
The increases of O-atoms and of H-atoms in the reaction between H2 and O2 in shock waves were measured over the temperature range of 1000–1400 K by atomic resonance absorption spectroscopy. The induction times of the absorptions by these two species were evaluated and computer modeling was carried out to reproduce these values. As one of the initiations of the H2–O2 reaction, H2+O2=H+HO2 was found to play an important role in the progress of the reaction. The rate constant of this reaction was evaluated as: k=4.1×1016 exp(−285 kJ/RT) cm3·mol−1·s−1.
A Model Study of Rhodopsin Regeneration in Visual Cell. Photoisomerization of all-trans Retinal in Phosphatidylcholine Vesicles
Authors: Tanie Hiroshi , Ohba Katsunori , Sakurai Minoru , Inoue Yoshio , Chûjô Riichiro 
Published: July 2006

Abstract
The photochemical behavior has been investigated for all-trans retinal in egg york phosphatidylcholine(EPC) vesicles and dipalmitoylphosphatidylcholine (DPPC) vesicles. In EPC vesicles, 10% of all-trans isomer is isomerized to 11-cis one upon direct irradiation of 15 W-fluorescence light for 180 min. In organic solvents the photoisomerization of all-trans isomer is induced depending on the dielectric constant of solvent. The distributions of retinal isomers in EPC vesicles is similar to those obtained in less polar solvents, such as diethyl ether. Significant difference is not recognized between the distributions of retinal isomers in DPPC vesicles at the above and below Tc. These results indicate that photoisomerization of retinal in PC vesicles is dominated by the electric properties of enviroment of retinal rather than the packing effect of PC membrane.
Ortho Effects in Organic Molecules on Electron Impact 17-Parallel Oxygen Transfers from Nitro Group to Olefinic Double Bond and Sulfur in α-(o-Nitrophenylthio)cinnamic Acids
Authors: Ramana D V , Sundaram N , George M 
Published: July 2006

Abstract
An oxygen transfer from the nitro group to the olefinic double bond followed by a simple cleavage affords intense fragment corresponding to o-nitrosophenylthio cation at m/z 138 during the mass spectral fragmentations of α-(o-nitrophenylthio)cinnamic acid. Single and double oxygen transfers from the nitro group to sulfur lead to concerted ejections of [SO+CO2] and [SO2+CO2] from the molecular ion of this compound. The mechanisms proposed for these processes are supported by high-resolution data, CID linked scan spectra, D-labelling, and chemical evidence.
The Thermal Decomposition of Ammonium Strontium cyclo-Tri-, cyclo-Tetra-, and cyclo-Hexaphosphate
Authors: Takenaka Atsushi , Motooka Itaru , Nariai Hiroyuki 
Published: July 2006

Abstract
Ammonium strontium cyclo-triphosphate Sr(NH4)P3O9·3H2O [P3m], cyclo-tetraphosphate Sr(NH4)2P4O12 [P4m], and cyclo-hexaphosphate Sr2(NH4)2P6O18·7H2O [P6m] were prepared by a wet method. The thermal decomposition of the cydo-phosphates was investigated by means of TG-DTA, HPLC-FIA, X-ray analysis, and IR spectrometry. Streams of humid air and dry nitrogen gas were used to clarify the effect of humidity on the pyrolysis. The decomposition of the ring structure of P3m and P4m was accompanied by the elimination of ammonia. Although P6m lost some of the waters of crystallization without any change in the structure, the ring was cleaved by the release of the other waters of crystallization. Regardless of the cyclo-phosphates, the final crystalline product was β-Sr(PO3)2, with a long-chain anion. The formation of β-Sr(PO3)2 was facilitated by water vapor in the cases of P3m and P6m. Unlike the pyrolysis of (NH4)6P6O18·1.5H2O and (NH4)4P4O12, it was unlikely that P3m, P4m, and P6m were decomposed to produce oligophosphate radicals. They were probably hydrolyzed to oligophosphates; then, polyphosphates were formed by the condensation of the oligophosphates.
The Preparation, Stereochemistry, and Oxidation of 2-Pyridinethiolato Cobalt(III) Complexes, and the Crystal Structure of [Co(2-pyridinethiolato)(en)2](ClO4)2
Authors: Kita Masakazu , Yamanari Kazuaki , Shimura Yoichi 
Published: July 2006

Abstract
A series of mixed complexes [Co(pyt)3−n (diamine)n]n+ (n=0, 1, and 2; pyt=2-pyridinethiolate(1—) and diamine=ethylenediamine, (R)-propylenediamine, or 2,2′-bipyridine) have been prepared and characterized by means of their visible and ultraviolet absorption, circular dichroism, and magnetic circular dichroism spectra. In the [Co(pyt)3] or [Co(pyt)2(diamine)]+ complex, only one geometrical isomer, mer(S) or trans(S) respectively, has been obtained. The [Co(pyt)(en)2](ClO4)2 complex, which was spontaneously resolved, had an orthorhombic space group of P212121, with a=12.406(1), b=12.754(1), c=11.621(4) Å, V=1838.7(6) Å3, and Z=4. The refinement of 2276 reflections (Mo Kα radiation) led to R=0.049. The Co–N bond trans to the pyt sulfur atom was longer by 0.023(11) Å than the cis one. The novel oxidation product [Co(2-pyridinesulfenato-N,S)(en)2]2+ was photochemically converted into the N,O-chelated linkage-isomer [Co(2-pyridinesulfenato-N,O)(en)2]2+ in the solid state, accompanied by ring-expansion from a four- to a five-membered chelate ring.
Association of Some Polynuclear Aromatic Hydrocarbons with Cyclodextrins in Aqueous Medium
Authors: Sanemasa Isao , Takuma Tatsuyoshi , Deguchi Toshio 
Published: July 2006

Abstract
Complex formation using cyclodextrins (CyDs) as hosts and anthracene, phenanthrene, and naphthacene as guests has been studied in aqueous medium at 25 °C by measuring the guest volatilization rate. The results obtained are compared with those previously determined for benzene and naphthalene. Factors governing the host–guest association are discussed based on the dehydration energy of the guest derived from the Henry’s law constant. It was suggested that van der Waals force is the main factor to stabilize the polynuclear aromatic hydrocarbons in the CyD cavity and that the contribution of hydrophobic interaction is less important. The additional van der Waals stabilization does not work fully for naphthacene of the longest molecular axis among the guests studied.
Facial–Meridional Isomerization of Some Tris(β-diketonato)ruthenium(III) Complexes
Authors: Kobayashi Kyohko , Satsu Yuichi , Hoshino Yoshimasa , Arai Shinji , Hatakeyama Kiyoshi , Endo Akira , Shimizu Kunio , P. Satô Gen 
Published: July 2006

Abstract
Nine complexes of type [RuII(R–CO–CH–CO–R′)3] were examined; only those with R=–CF3 underwent the facial–meridional isomerization in N,N-dimethylformamide (DMF) at the reflux temperature. Qualitative examination of the occurrence of isomerization of the complex with R=–CF3 and R′=–CH3 in various solvents supports the presence of solvent-assisted bond-rupture mechanisms. This complex did not isomerize photochemically in acetonitrile. The isomerization of four complexes with R=–CF3 and R′=–CH3, –C2H5, –CH-(CH3)2, and –C(CH3)3 in DMF at 70–100 °C followed the reversible first-order kinetics. The equilibrium constants, which were temperature independent, decreased from 4.27 to 1.74 in the order cited above. The enthalpies of activation, ranging from 66.4 kJ mol−1 (R′=–CH(CH3)2) to 96.0 kJ mol−1 (R′=–CH3), depended linearly on the atomic bond populations of the Ru–O bonds calculated by means of a modified extended Hückel method.
Ortho Effects in Organic Molecules on Electron Impact. 20. Parallel Oxygen Transfers from Nitro Group to Sulfur and Acetylenic Triple Bond in 3-(o-Nitrophenylthio)-1-propynes
Authors: Ramana DV , Rama Krishna N V S 
Published: July 2006

Abstract
Oxygen transfers from nitro group to both the sulfur and acetylenic triple bond are noticed in parallel fragmentation pathways during the electron impact induced decompositions of 3-(o-nitrophenylthio)-1-propynes. Single oxygen transfer from nitro group to sulfur leads to abundant ions corresponding to o-nitrosobenzenesulfinyl cation and [M–SO]+· while a concerted double oxygen transfer to sulfur followed by ejection of SO2 from the rearranged molecular ion affords intense quinoline radical cation. Further, a single oxygen transfer to acetylenic triple bond, followed by a simple cleavage produces intense fragments corresponding to o-nitrosobenzenethiol radical cation at m/z 139 and o-nitrosophenylthio cation at m/z 138. The proposed fragmentation pathways and ion structures are established through high-resolution data, collisioninduced dissociation (CID) mass-analyzed ion kinetic energy (MIKE) spectra, B/E linked scan spectra and chemical substitution.
The Magnetic Properties of Dinuclear Copper(II) 2-Fluoroalkanoates
Authors: Emori Shuji , Kondo Hideki 
Published: July 2006

Abstract
Copper(II) pentafluoropropionate and heptafluorobutyrate adducts with 1,4-dioxane, tetrahydropyran, and tetrahydrofuran have been prepared and characterized by means of magnetic-susceptibility and IR-spectroscopy measurements. The variation in their magnetic moments is discussed in terms of the acidity of the parent acid and the hyperconjugative effect of the fluoroalkyl group.
Selective Lithium Ion Transport through Hollow-Fiber Membrane Containing Easily-Dissociable 14-Crown-4 Derivative
Authors: Sakamoto Hidefumi , Kimura Keiichi , Tanaka Minoru , Shono Toshiyuki 
Published: July 2006

Abstract
A flow-through transport system was fabricated by using a hollow-fiber impregnated with a 14-crown-4 dinitrophenol solution and was found to allow selective Li+ transport.
Extractive Separation and Determination of Lead in Alloys and Environmental Samples
Authors: Raman Bhanu , Shinde V M 
Published: July 2006

Abstract
A method is proposed for the solvent extraction of lead salicylate using triphenylphosphine oxide as an extractant. The optimum extraction conditions were evaluated from a critical study of effects of pH, sodium salicylate concentration and triphenylphosphine oxide concentration. The probable composition of the species has been deduced from log–log plots and the extraction mechanism is suggested. The method has been used to separate lead from commonly associated elements such as copper, nickel, antimony; and also from chromium, iron, and mercury. The method has been further extended to separate and estimate lead in standard alloys, gasoline, and air-borne particulate samples.
Electrogenerated Acid-Catalyzed Michael Reaction of Enol Silyl Ethers and Ketene Silyl Acetals to α,β-Unsaturated Carbonyl Compounds
Authors: Inokuchi Tsutomu , Kurokawa Yuji , Kusumoto Masahiko , Tanigawa Shinichi , Takagishi Sadahito , Torii Sigeru 
Published: July 2006

Abstract
1,5-Dicarbonyl compounds and their enol silyl ethers were prepared by the reaction of α,β-unsaturated ketones and enol silyl ethers or ketene silyl acetals by using an electrogenerated acid (EG acid) as a catalyst. Similar reaction of 1-trimethylsiloxy-1,3-butadiene with enones produced six-membered adducts as the result of a double-Michael process.
Computer Simulations of Gel Filtration Chromatograms of Rapidly Self-Associating Systems
Authors: Funasaki Noriaki , Hada Sakae , Neya Saburo 
Published: July 2006

Abstract
A computer simulation method for gel filtration chromatography (GFC), based on plate theory and mass action law, is developed for rapidly self-associating systems and compared with asymptotic theory. For ovalbumin, a non-associable protein, whose elution volume increases linearly with increasing concentration, the leading boundary is predicted to be broader than the trailing. Computer simulations are used to estimate the aggregation numbers and the equilibrium constants for dimerization of carbonylhemoglobin and hexamerization of α-chymotrypsin. The concentration, Cmin, at the plateau region of the trailing boundary is shown to be close to cmc by asymptotic theory. The present computer simulation and derivative GFC patterns serve to estimate monomer concentration and micellar size of surfactants from analysis of GFC data.
Cobalt(III) Complexes with Quadridentate Ligands. X. The Preparation and Properties of Isomers of the Salicylaldehydato(quadridentate amine)cobalt(III) Complexes
Authors: Toyota Eiko , Yamamoto Yoshihisa 
Published: July 2006

Abstract
In a recent study, t- and p-salicylaldehydato[tris(2-aminoethyl)amine]cobalt(III) complexes, t- and p-[Co(salad)tren]Cl2·H2O, and cis-β1- and β2-RR,SS-salicylaldehydato(quadridentate amine)cobalt(III) complexes, cis-β1- and β2-RR,SS-[Co(salad)L]Cl2·nH2O (L: 2,3,2-tet; 3,2,3-tet), have been obtained from a reaction mixture of [CoCl2L]Cl·nH2O (L: tren; 2,3,2-tet; 3,2,3-tet), Ag2O, and salicylaldehyde. Two isomers were separated for each complex by SP-Sephadex C-25 column chromatography. The formation ratio of t- to p-isomers was ca. 1:3. The t- and p-configurations have been established by their absorption and 1H NMR spectra. On the other hand, the formation ratio of cis-β1 to β2-RR,SS-isomers was ca. 1:1 for both L=2,3,2-tet and 3,2,3-tet ligands. Their configurations have been established by their IR, absorption, and NMR spectra. The corresponding cis-α-isomer could not be obtained. Isomerization between t- and p-isomers or cis-β1- and β2-isomers was not observed in water at room temperature. The formation ratio and the absorption spectra of the complexes are different from those of the corresponding salicylato(quadridentate amine)cobalt(III) chloride hydrate, [Co(sal)L]Cl·nH2O (L: tren; 2,3,2-tet; 3,2,3-tet), previously reported. These differences have been attributed to a carbonyl bond between the carbonyl oxygen of the formyl group and a cobalt atom in the complexes.
Solvent Effects on the Formation of Copper(II) Chloro Complexes in Acetonitrile-Dimethyl Sulfoxide Mixtures
Authors: Ishiguro Shin-ichi , Suzuki Honoh , G. Jeliazkova Bojana , Ohtaki Hitoshi 
Published: July 2006

Abstract
Complexation of copper(II) with chloride ions has been calorimetrically and spectrophotometrically studied in various acetonitrile (AN)–dimethyl sulfoxide (DMSO) mixtures at 25 °C. Complexation of copper(II) ion with DMSO as a ligand in AN has also been investigated calorimetrically. It is indicated that the solvent effect on the thermodynamic parameters of the complexation is dominated by two factors, (1) the preferential solvation of copper(II) ion with DMSO that mainly affects the enthalpies, and (2) the change in solvent–solvent interactions in the bulk that strongly affects the corresponding entropies.