bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polarographic Determination of Bismuth, Copper, Iron(III), Palladium, and Uranium(VI) after Extraction into Molten Naphthalene with Oxine
Authors: Puri B K , Gautam Mamta , Fujinaga Taitiro 
Published: July 2006

Abstract
A rapid extraction-polarographic method has been developed for the direct determination of bismuth, copper, iron(III), palladium, and uranium(VI) extracted into the organic phase. Oxinates of metals were extracted into molten naphthalene at different pH values. With lowering of temperature, naphthalene separated out as a solid containing the metal oxinates. The solid mass was dissolved in DMF and the polarograms were recorded in the presence of a suitable supporting electrolyte. The metal oxinates give well defined waves. The relation between diffusion current and concentration is linear over a wide range of concentration with an average relative error not more than 1.05%. Interferences of various ions have been studied of the anions studied, only EDTA interfered in the extraction of bismuth, copper, iron(III), and uranium(VI). Of the cations studied, palladium interfered in the determination of bismuth, copper, iron(III), and uranium(VI). However, the intereference was eliminated by carrying out extraction first at low pH. In the determination of bismuth only copper interfered but its interference can also be eliminated as in the case of palladium. In the case of copper determination, only iron(III) interfered. In the determination of iron, copper interfered but interference can be eliminated by using a suitable masking agent. The determination of palladium and uranium(VI) is free from all interferences.
Kinetics and Mechanism of the Oxidation Reactions of Dialkyldithiocarbamatocopper(I) Tetramer and -silver(I) Hexamer with Tetraalkylthiuram Disulfide
Authors: Kita Hidetoshi , Miyake Shin-ichi , Tanaka Koji , Tanaka Toshio 
Published: July 2006

Abstract
Kinetics of the oxidations of dialkyldithiocarbamatocopper(I), [{Cu(S2CNR2)}4] (R=Et, n-Pr), and -silver(I), [{Ag(S2CNR2)}6] (R=Et, n-Pr, i-Pr), with the corresponding tetraalkylthiuram disulfide, [(R2NC(S)S) \llap–2], were investigated in dichloromethane employing a stopped-flow technique. The reactions are interpreted to proceed by a mechanism involving a rapid equilibration (i) (the multi-step equilibrium constant=K0) to form adduct,
(Remark: Graphics omitted.)
[M(S2CNR2){(R2NC(S)S) \llap–2}], which are decomposed in a rate-determining step (the rate constant=k) yielding the final products, [M(S2CNR2)2]. According to this mechanism, the rate law in the presence of excess [(R2NC(S)S) \llap–2] is expressed as v=K0k[[(R2NC(S)S) \llap–2]][[{M(S2CNR2)}x]]/(1+K0[[(R2NC(S)S) \llap–2]]), where K0k(25 °C)=1.17×104 (Et), 5.70×103 (n-Pr) M−1 s−1 (M=mol dm−3) for the copper system, and K0(25 °C)=28.2 (Et), 49.1 (n-Pr), 86.7 (i-Pr) M−1 and k(25 °C)=2.17 (Et), 1.50 (n-Pr), 6.56 (i-Pr) s−1 for the silver system. The activation parameters also were determined and the nature of transition states is discussed.
CNDO/2 Parametrizations and the Applications to Some Organosulfur Molecules: (CH2SH)2, (CH2SCH3)2, CH3SCH2SH, and CH3SCH2SCH3
Authors: Ohsaku Masaru , Bingo Norihisa , Sugikawa Wataru , Murata Hiromu 
Published: July 2006

Abstract
The CNDO/2 spd′ parametrizations of Kd, βc, ζs, and βs have been performed. Some of the valence and torsional angles of 1,2-ethanedithiol (CH2SH)2, 1,2-bis(methylthio)ethane (CH2SCH3)3, methanethiol, ethanethiol, (methylthio)methanethiol CH3SCH2SH, and bis(methylthio)methane CH3SCH2SCH3 have been optimized. In order to obtain further information on the rotational isomerism, CNDO/2 spd′ and sp calculations have been conducted for the molecules with variations in torsional angle.
Spectrophotometric Determination of Cadmium(II) with Dithizone and 1,10-Phenanthroline
Authors: Akaiwa Hideo , Kawamoto Hiroshi , Yoshimatsu Eiji 
Published: July 2006

Abstract
Cadmium(II) has been quantitatively separated from zinc(II) by an ion-pair extraction system. An ion-pair consisting of cadmium(II) and 1,10-phenanthroline (phen) was found to be preferentially extracted into chloroform from an aqueous chloride solution containing zinc(II). The extracted species in chloroform reacted with dithizone (H2Dz) to give the reddish mixed complex Cd(HDz)2(phen) having an absorption maximum at approximately 505 nm. The resulting calibration curve obeys Beer’s law, the Sandell sensitivity being 0.0013 μg cm−2. The effect of diverse ions has been examined, and a new highly selective method for the spectrophotometric determination of trace amounts of cadmium in metallic zinc established.
Reaction of Dimethyl Phosphonate with Ketene Dimethyl Dithioacetal Derivatives. An Alternative Method to Prepare s-Alkylphosphonates
Authors: Yamashita Mitsuji , Miyano Tadaaki , Watabe Takashi , Inokawa Hiromi , Yoshida Hiroshi , Ogata Tsuyoshi , Inokawa Saburo 
Published: July 2006

Abstract
Reaction of dimethyl phosphonate with phenylketene dimethyl dithioacetal derivatives have been investigated to prepare s-alkylphosphonates. The addition reactions of phosphonate were accelerated in dithioacetal derivatives in the following order: –SMe&lt;–SOMe&lt;&lt;–SO2Me. The reaction of β,β-bis(methylsulfonyl)styrene (7) with dimethyl phosphonate followed by the catalytic reduction afforded dimethyl α-methylbenzylphosphonate in 74% yield from compound 7. The reaction of 1-methylsulfinyl-1-methylthio-4-phenyl-1-butene with dimethyl phosphonate gave dimethyl (2-methylthio-1-phenethylvinyl) phosphonate in 21% yield.
Crystal Structure of 5-Bromocytosine
Authors: Kato Masuhiro , Takenaka Akio , Sasada Yoshio 
Published: July 2006

Abstract
The crystal structure of 5-bromocytosfne has been determined by X-ray analysis to investigate the bromination effect on the cytosine moiety. The space group is P21/a, with dimensions a=16.943(2), b=9.155(1), c=3.846(1) Å, β=99.89(1)°, and Z=4, The structure was solved by the heavy-atom method and refined by the full-matrix least-squares method. A comparison with the cytosine structure indicates some large deviations in bond lengths and angles, which are attributed to the steric and electronic effects caused by bromination. After the VSEPR theory, the slight increase of C(2)–N(3)–C(4) angle (0.8°) is interpreted as the decrease of the effective charge of the lone pair on N(3), and this is related to the difference of pKa values between 5-bromocytosine and cytosine.
Reactions of 2′-Hydroxyisoflavone and 2′-Hydroxy-2-methylisoflavones with Metal Salts
Authors: Kurosawa Kazu , Araki Fukuo 
Published: July 2006

Abstract
Reactions of four 2′-hydroxy-2-methylisoflavones with lead(IV) acetate gave the corresponding l0b-acetoxy-5a-methyl-5a,10b-dihydrobenzofuro[2,3-b][1]benzopyran-11-ones in 21–25% yields and 2-(2-methyl-4-oxo-4H-chromen-3-yl)-p-benzoquinones in 27–46% yields. Reactions of the isoflavones with manganese(III) acetate gave the ketones in 1–25% yields. Reaction of 2′-hydroxy-4′,7-dimethoxyisoflavone with lead(IV) acetate gave 10b-acetoxy-3,8-dimethoxy-5a,10b-dihydrobenzofuro[2,3-b][1]benzopyran-11-one, and 3,8-dimethoxybenzofuro[2,3-b][1] benzopyran-11-one.
Preparation and Isomerization of Isomers of the l- or d-Aspartato(l-histidinato)cobalt(III) Complex
Authors: Watabe Masatoshi , Yano Hisao , Yoshikawa Sadao 
Published: July 2006

Abstract
The six isomers of the [Co(l- or d-asp)(l-his)] complex (asp=aspartate ion and his=histidinate ion) have been prepared and the isomerization studied in the absence of any catalyst. The equilibrium mole fractions of these isomers in water has been found for l-transO5cisN5, l-cisO5transN5, l-fac, to be 0.53, 0.06, and 0.41, respectively, those for d-cisObcisN5, d-transO5transN5, and d-fac to be 0.48, 0.01, and 0.51 respectively. The indication is that the relative positions of the six coordinated atoms around a cobalt atom cause these unequal isomer concentration ratios. The isomerisms are dealt with by means of a network of first order reversible reactions and the absolute values of the rate constants at 80 °C have been determined.
A Broad-line NMR Study on Some Pyrene Complexes: Molecular Motion and Isomorphism in the High-temperature Forms
Authors: Inabe Tamotsu , Matsunaga Yoshio , Yoshida Yuji 
Published: July 2006

Abstract
The pyrene complexes with six polynitro aromatic compounds are isomorphous to each other above the transition temperatures. The onset of a large degree of molecular motion has been shown from broad-line NMR measurements to occur at the transition temperature of all the six complexes.
The Structure of Yahazunol, a New Sesquiterpene-substituted Hydroquinone from the Brown Seaweed Dictyopteris undulata Okamura
Authors: Ochi Masamitsu , Kotsuki Hiyoshizo , Muraoka Kiyoshi , Tokoroyama Takashi 
Published: July 2006

Abstract
The structure of yahazunol, an antimicrobial substance isolated from the brown seaweed D. undulata Okamura, was established on the basis of spectral and chemical evidence.
The Photochemical Reaction of Benzo[c]cinnoline. III. Mechanism of Carbazole Formation
Authors: Inoue Hiroyasu , Hiroshima Yukimi , Miyazaki Kiyoto 
Published: July 2006

Abstract
5,6-Dihydrobenzo[c]cinnoline is an intermediate in the photochemical formation of carbazole from benzole[c]cinnoline. The mechanism of the photo-induced carbazole formation from 5,6-dihydrobenzo[c]cinnoline has been studied in acidic aqueous 2-propanol of the reactant previously produced by the photo-reduction of benzo[c]cinnoline. It has been established that only the protonated species of the reactant undergoes photoreaction. The results of quenching experiments on quantum yields for the reaction and on the fluorescence of the reactant have shown that the reactive state is the first excited singlet state of protonated 5,6-dihydrobenzo[c]cinnoline. The initial step in the reaction is the hydrogen atom abstraction followed by elimination of the amino radical.
Transport of Picrate Anion against Its Concentration Gradient through a Dichloroethane Membrane
Authors: Sugiura Masaaki , Shinbo Toshio 
Published: July 2006

Abstract
The rate of picrate transport coupled to a diffusion of potassium ions through a bulk 1,2-dichloroethane membrane has been measured. The membrane, containing a potassium ionophore separated two aqueous phases, one containing picrate and potassium salt and the other containing picrate and lithium salt. The picrate anion was accumulated against the concentration gradient in the aqueous phase containing the lithium salt. The rate of picrate transport incrased with increasing ionophore concentration and in the absence of the ionophore, the transfer of picrate did not occur. The effect of potassium and lithium counter-ions such as chloride, nitrate and sulfate on the transport of picrate has been examined. The combination of potassium sulfate and lithium nitrate showed the highest rate of transport. In the potassium nitrate-lithium nitrate system, the transport of picrate was appreciably depressed by the transfer of nitrate ions across the membrane. The decrease in concentration of potassium ion in the aqueous phase brought about a lowering of the rate of picrate transport. The rate of picrate transport rose according to the following order of ionophore : dicyclohexyl-18-crown-6&gt;dicyclohexyl-24-crown-8&gt;dibenzo-18-crown-6&gt;dibenzo-24-crown-8&gt;valinomycin.
The Rates of the Hydrogenation of the Coordinated Styrene and Acrylonitrile in a Rhodium-Olefin Complex [RhClH2(ol)(PPh3)2]
Authors: Ohtani Yoshimi , Yamagishi Akihiko , Fujimoto Masatoshi 
Published: July 2006

Abstract
Kinetics of the hydrogenation of coordinated styrene and acrylonitrile in a rhodium-olefin complex RhClH2(ol)(PPh3)2 (ol=styrene or acrylonitrile) was studied by stopped-flow method and by the direct measurements of hydrogen-gas uptake. The equilibrium constant of the reaction RhCl(ol)(PPh3)2+H2\ightleftharpoonsRhClH2(ol)(PPh3)2, K34, and the rate of the hydrogenation of the olefin in the complex RhClH2(ol)(PPh3)2, k45, were determined to be 3.2×103 mol−1 dm3 and 2.7 s−1 for styrene, and 3.5×102 mol−1 dm3 and 0.50 s−1 for acrylonitrile, respectively. The differences in the values for these two olefins were discussed. The data for cyclohexene were also briefly mentioned.
Molecular Structure and Internal Rotation of Trimethylamine-Boron Trifluoride. A Combination of Electron Diffraction and Spectroscopic Data
Authors: Iijima Kinya , Shibata Shuzo 
Published: July 2006

Abstract
The molecular structure of trimethylamine-boron trifluoride (CH3)3N·BF3 was determined from gas electron-diffraction data with vibrational and rotational spectroscopic data. The geometric parameters of the molecule were found to be very close to those inferred from the preliminary analysis of the diffraction data alone. The structural parameters and uncertainties were rg(N–B)=1.674(4) Å, rg(B–F)=1.374(2) Å, rg(C–N)=1.485(2) Å, rg(C–H)=1.100(3) Å, rg(F…F)=2.288(2) Å, and rg(C…C)=2.420(4) Å. The potential barrier about the N–B axis was estimated to be 4.3±0.3 kcal/mol in the gas phase; this value is much larger than that from NMR spectra.
Glucosidation of Tetra-O-benzyl-α-d-glucose with Chlorosilane and Silver Sulfonate
Authors: Koto Shinkiti , Morishima Naohiko , Zen Shonosuke 
Published: July 2006

Abstract
Glucosidation of 2,3,4,6-tetra-O-benzyl-α-d-glucopyranose with methanol or cyclohexanol in the presence of chlorosilane and silver sulfonate is described. As by-products, octa-O-benzyl-α,α- and -α,β-trehaloses are also formed. Possible reaction pathways are discussed.
Photolysis of Organic Azides. IV. Formation of o-Xylylene Derivatives from 2,3-Diazidonaphthalenes. Direct Observation by Low-temperature and Flash Photolysis
Authors: Yabe Akira 
Published: July 2006

Abstract
The photolysis of 2,3-diazidonaphthalene (3a) in a rigid matrix at 77 K gave the product having absorption bands in the 400–500 nm region, which has been assigned as α,ω-dicyano-o-xylylene (2a) by use of another precursor 1,2-dicyano-1,2-dihydrobenzocyclobutene. 2a has been also observed by the flash photolysis of 3a in fluid solution at room temperature, and the lifetime in methanol at 20 °C was 62 s. The dominating factor in the lability of 2a was the rigidity of the medium rather than the temperature. The reaction mechanism for the formation of 2a from 3a has been proposed as a monophotonic process involving the attack of the nitreno group on the azido group at the ortho position. Similarly, direct observations of α,ω-dimethoxy- and α,ω-diacetoxy-α,ω-dicyano-o-xylylenes have been given from 1,4-dimethoxy- and 1,4-diacetoxy-2,3-diazidonaphthalenes respectively.
The Structure and Configuration of (+)-Glutionosone and (+)-Oxyglutinosone
Authors: Murai Akio , Taketsuru Hirofumi , Yagihashi Fujio , Katsui Nobukatsu , Masamune Tadashi 
Published: July 2006

Abstract
The structure elucidation of (+)-glutinosone and (+)-oxyglutinosone, antifungal norsesquiterpenes qualified as phytoalexins in diseased tobacco leaves and in diseased potato tubers, respectively, is described.
Modification of (S)-N,N-Dimethyl-1-[(R)-1′,2-bis(diphenylphosphino)ferrocenyl]ethylamine (BPPFA) as a Ligand for Asymmetric Hydrogenation of Olefins Catalyzed by a Chiral Rhodium(I) Complex
Authors: Yamamoto Keiji , Wakatsuki Junya , Sugimoto Ryuichi 
Published: July 2006

Abstract
Asymmetric homogeneous hydrogenation of prochiral olefins catalyzed by chiral rhodium(I) complexes was carried out by using several ferrocenylphosphines as ligands which play a key role of the chiral recognition. Modifications of BPPFA were made in order to examine a steric effect of the given substutient at the asymmetric center on the efficiency of the chiral ligands, indicating the parent BPPFA to be superior to the others examined for the asymmetric hydrogenation of highly functionalized olefins.
Cyclotrimerization of Phenylacetylene Catalyzed by Halides of Niobium and Tantalum
Authors: Masuda Toshio , Mouri Taizo , Higashimura Toshinobu 
Published: July 2006

Abstract
Halides of niobium and tantalum (NbX5, TaX5; X=Cl, Br, F) catalyzed the cyclotrimerization of phenylacetylene in hydrocarbon and chlorinated hydrocarbon solvents at 0–90 °C. When NbCl5 and TaCl5 were used as catalysts, two cyclic trimers, 1,2,4- and 1,3,5-triphenylbenzenes were exclusively formed, and their ratio varied from 17:83 to 94:6 depending on reaction conditions. The cyclotrimerization was more selective than those by other known catalysts. The cyclotrimerization by NbBr5 and TaBr5 occurred in a similar manner, but the reaction was less selective than that catalyzed by NbCl5 and TaCl5. Not only cyclotrimerization but also linear oligomerization proceeded by NbF5 and TaF5 as catalysts. The results obtained were discussed together with the linear polymerization of phenylacetylene catalyzed by MoCl5 and WCl6.
Surface Composition of SnO2–ZrO2 Binary Oxide Catalyst and Its Selectivity for C3H6–NO Reaction
Authors: Imanaka Toshinobu , Hashimoto Takeshi , Sakurai Katsumi , Okamoto Yasuaki , Teranishi Shiichiro 
Published: July 2006

Abstract
The relation between the composition of outermost surface layer on SnO2–ZrO2 binary oxide catalyst and catalytic selectivity in the C3H6–NO reaction has been investigated by XPS technique. The composition of outermost surface layer was estimated from a comparison of the intensity ratios of X-ray induced Auger peak or XPS peak of Sn to XPS peak of Zr. A superficial enrichment of Zr was observed in these catalysts calcined at 600 °C in the air, while surface enrichment of Sn took place during the course of evacuation at 450 °C. The catalytic selectivity for formation of acrylonitrile showed a maximum with the catalyst containing Sn and Zr in the same concentration at the outermost surface layer of catalyst.
Topological Index and Thermodynamic Properties. II. Analysis of the Topological Factors on the Absolute Entropy of Acyclic Saturated Hydrocarbons
Authors: Narumi Hideyuki , Hosoya Haruo 
Published: July 2006

Abstract
The absolute entropy of acyclic saturated hydrocarbons is found to be well correlated linearly with the logarithm of the topological index (ZG) of the graph of the carbon atom skeleton as, S°=alogZG+b, excpet for sterically overcrowded and highly symmetrical molecules. This relation is improved by taking the symmetry factor σ into account as, S°=alogZG+b+clogσ. The physical meaning of these relations is clarified by analyzing the mathematical properties of ZG and the rotational partition function proposed by Pitzer.
The Collection of Uranium from Sea Water with Hydrous Metal Oxide. III. The Effects of Diverse Ions in Sea Water on Uranium Adsorption by Hydrous Titanium(IV) Oxide
Authors: Yamashita Hisao , Ozawa Yoshihiro , Nakajima Fumito , Murata Toshifumi 
Published: July 2006

Abstract
The effect of diverse ions present in sea water on the uranium adsorption is elucidated in the present paper. The uranium-adsorption experiments were conducted using sea water and a solution containing 0.72 mol dm−3 NaCl and 2.3×10−3 mol dm−3 NaHCO3. The uranium uptake was about ten times larger from the NaCl–NaHCO3 solution than from sea water. The ions which depressed the uranium uptake were the calcium, magnesium, and fluoride present in sea water. Among these ions, calcium had the largest effect on the uranium uptake. The analysis of calcium and carbonate in the adsorbent after the adsorption experiment has revealed that the molar ratio between calcium and carbonate was about one. It was considered that calcium carbonate was deposited on the adsorbent during the uranium adsorption. The specific surface area and the pore volume decreased after the deposition of calcium carbonate. It was supposed that the decrease in the uranium uptake was caused by the coverage of the surface of hydrous titanium(IV) oxide with calcium carbonate. Magnesium ions depressed the uranium uptake in the same manner as calcium ions. The effect of the magnesium ions, however, was relatively small compared with that of the calcium ions.
Aldol Condensations with Metal(II) Complex Catalysts
Authors: Irie Kazuo , Watanabe Ken-ichi 
Published: July 2006

Abstract
Aldol condensations of aldehydes with ketones catalyzed by the first-row transition metal(II) complexes have been widely studied. Complexes of Co(II), Ni(II), Cu(II), and Zn(II) acetates with 2,2′-bipyridine were effective catalysts to afford cross-aldol condensation products, α,β,-unsaturated ketones, in high yields without any self-condensation products. The reaction of 2-butanone, unsymmetrical aliphatic ketone, with benzaldehyde took place regioselectively to give base-catalyzed-type products.
Preparation and 1H-NMR Spectra of Dialkyl{tetrakis(1-pyrazolyl)borato}thallium(III) Complexes
Authors: Onishi Masayoshi , Hiraki Katsuma , Nakagawa Shigeki 
Published: July 2006

Abstract
Diethyl- and dibuthyl{tetrakis(1-pyrazolyl)borato}thallium(III) complexes were prepared and characterized. The 1H-NMR spectra of pyrazolyl protons of the BPz4 ligand as well as the coupling constants between thallium and alkyl protons are discussed.
New Applications of Crown Ethers. II. Synthesis of 4′-Formylbenzocrown Ethers
Authors: Wada Fumio , Hirayama Hiroshi , Namiki Hiroshi , Kikukawa Kiyoshi , Matsuda Tsutomu 
Published: July 2006

Abstract
4′-Formylbenzo-15-crown-5, -18-crown-6, and bis(4′-formylbenzo)-18-crown-6 were conveniently synthesized in excellent yields by Smith modification of Duff reaction: formylation with hexamethylenetetramine and trifluoroacetic acid or methanesulfonic acid.
Oxidation of Nitrotoluenes with Electro-generated Superoxide Ion
Authors: Sagae Hiromitsu , Fujihira Masamichi , Lund Henning , Osa Tetsuo 
Published: July 2006

Abstract
The oxidation of o-, m-, and p-nitrotoluenes with electro-generated superoxide ion in dimethylformamide was studied using cyclic voltammetry and controlled potential macro-electrolysis. The electrochemical reduction of oxygen in the presence of o- and p-nitrotoluenes yielded the corresponding carboxylic acids because the methyl groups in these derivatives are activated by the nitro group. An intermediate in these oxidations should be the corresponding nitrobenzaldehyde. The reaction mechanism is discussed.
Solvent Effects on the Photoamination of 1-Amino-2,4-dibromoanthraquinone. II. Dual Mode of the Photoamination in Ethanol via the S1(1CT) and T1(3CT) States
Authors: Inoue Haruo , Shinoda Tsutomu , Hida Mitsuhiko 
Published: July 2006

Abstract
The photoamination of 1-amino-2,4-dibromoanthraquinone (1) by butylamine in ethanol was investigated. The reaction was accelerated under an air atmosphere (Φair=1.7×10−3, ΦN2=2.3×104, where [butylamine]=5.00×10−2 mol/dm3). A detailed kinetic study indicated that, under nitrogen, the photoamination proceeded via the T1(3CT) state populated by the intersystem crossing from the S1(1CT) state, while under air it proceeded via both the T1(3CT) and the S1(1CT) states. The latter pathway under air included an interaction between the S1(1CT) state and oxygen to form an exciplex or a collisional complex such as [AQδ+···O2δ−]. The deactivation constant from the T1(3CT) of 1 in ethanol was revealed to be one order of magnitude smaller than that in benzene and one order magnitude larger than that of 1-aminoanthraquinone in benzene. These results were discuessd in relation to the energy diagram in the excited state and the intramolecular heavy-atom effect of bromine in 1.