bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and Characterization of Cobalt(III) Complexes Containing (CH3)2As(CH2)nAs(CH3)2 (n=2, 3)
Authors: Iwata Katsumi , Kojima Masaaki , Fujita Junnosuke 
Published: July 2006

Abstract
Twelve new complexes, trans-[CoX2(dmae or dmap)2]+ (X=Cl, Br, I; dmae=1,2-bis(dimethylarsino)ethane, dmap=1,3-bis(dimethylarsino)propane), cis-[CoX2(dmap)2] (X=Cl, Br), [Co(CO3)(dmae or dmap)2]+, and [Co(acac)3−n(dmap)n]n+(n=0, 1, 2; acac=2,4-pentanedionate ion) were prepared and characterized. From a comparison of the 1A1g→1Eg (D4h) d-d absorption bands of analogous trans-dichloro complexes of phosphines and amines, the order of spectrochemical series for the group 5B elements was suggested to be P&gt;As&gt;N. Largely reduced interelectronic repulsions between the crystal field levels were observed for the carbonato complexes. Isomerization of cis-[CoCl2(dmap)2]+ to the trans isomer was studied in methanol in the temperature range of 20.1–49.9 °C. The rate has a first-order dependence on the complex concentration. The rate constant at 54.9 °C, calculated from the ΔH\eweq (115.2 kJ mol−1) and ΔS\eweq (53.8 J mol−1 K−1) values, is 103 times as large as that reported for cis-[CoCl2(diars)2]+ (diars=o-phenylenebis(dimethylarsine)) at the same temperature.
Oxidation of Coals in Liquid Phases. VII. Oxidation of Oxygen-containing Model Compounds of Coal by Oxygen in Concentrated Sodium Hydroxide Solutions
Authors: Furuya Hirohide , Uwabe Ryoichi , Sutoh Nobuyuki , Okuwaki Akitsugu , Amano Akira , Okabe Taijiro 
Published: July 2006

Abstract
Oxidation of 26 model compounds of low-ranked coal was performed to study the formation mechanisms of oxalic acid from coal. A mixture of 0.02 mol of the model compound, 4–60 g of NaOH, and 50 g of water was placed in a 300 cm3 autoclave and oxidized at 523 K and PO2=5 MPa for 120 min. Acetic acid was produced from phenols within 15 min and oxidized selectively to oxalic acid. The yield ratio(yield of oxalic acid(%)/yield of CO2 (%)) from most of the model compounds was higher than 1. These phenomena agreed well with those of low-ranked coal under the same oxidation conditions. The overall reaction rates, yields of oxalic acid, and yield ratios increased rapidly with an increasing concentration of NaOH as in the oxidation of coal. This behavior can be explained resonably well by an alkali-catalyzed oxidation mechanism regarding organic substances.
A Set of Rate Constants for the Reactions of OH Radicals with Aromatic Hydrocarbons
Authors: Ohta Tomohiro , Ohyama Toshiro 
Published: July 2006

Abstract
The rate constants for the reactions of OH radicals with seventeen aromatic hydrocarbons were determined at atmospheric pressure and room temperature from competitive reactions with hexane, using H2O2 as the OH-radical source. A useful trend was found in the structure-reactivity relationship.
A Method for Determining Absolute Configuration of Cycloalkanamines and Related Compounds by CD Spectra of Their 2,4-Dinitrophenyl Derivatives
Authors: Kawai Masao , Iwase Teruhiko , Butsugan Yasuo , Nagai Ukon 
Published: July 2006

Abstract
N-(2,4-Dinitrophenyl) derivatives of cycloalkanamines and related compounds having an amino and an aromatic groups in vicinal positions were prepared. Their CD spectra exhibited marked Cotton effect around 400 nm, the sign of which was shown to coincide with the chirality between the two chromophore-bearing bonds. This relation, as a special example of exciton chirality method, is useful for determining absolute configuration of cyclic compounds having a primary amino group.
Thermal Decomposition of 2,2-Bis(t-butyldioxy)-3-methylbutane
Authors: Komai Takeshi , Suyama Shuji 
Published: July 2006

Abstract
The activation parameters for decomposition of 2,2-bis(t-butyldioxy)-3-methylbutane (2) in diphenylmethane are ΔH\eweq=144.8 kJ mol−1 and ΔS\eweq=49.4 JK−1 mol−1. The decomposition products of 2 are t-butyl alcohol, acetone, isopropyl methyl ketone and t-butyl peracetate. t-Butyl peracetate (4) is an intermediate which decomposes during reaction. This peroxide 2 decomposes with homolytic one-bond cleavage at one of the peroxide groups and the resulting 1-(t-butyldioxy)-1,2-dimethylpropoxyl radical (3) decomposes subsequently to t-butyldioxy or isopropyl groups with β-elimination.
Photochemical Reaction of 1,4-Naphthoquinone Derivatives with Pyrrole Derivatives. Synthesis of 2-(2-Pyrrolyl)-1,4-naphthoquinone Derivatives
Authors: Maruyama Kazuhiro , Otsuki Tetsuo , Tamiaki Hitoshi 
Published: July 2006

Abstract
Photochemical reaction of 2-bromo-1,4-naphthoquinone derivatives with pyrrole derivatives in benzene gave regioselectively 2-(2-pyrrolyl)-1,4-naphthoquinone derivatives. Photoinduced electron transfer process may be involved in the reaction.
Replacement of a Carbonyl Group of Camphor by an Oxygen Atom. Synthesis of 1,7,7-Trimethyl-2-oxabicyclo[2.2.1]heptane
Authors: Suginome Hiroshi , Yamada Shinji 
Published: July 2006

Abstract
A four-step transformation of (+)-camphor into a hitherto undescribed 1,7,7-trimethyl-2-oxabicyclo[2.2.1]heptane is described.
Enzymic Synthesis and Biochemical Activity of Various Indazole Adenine Dinucleotides
Authors: Tono-oka Shuichi , Tone Yukiko , E. Marquez Victor , A. Cooney David , Sekikawa Isao , Azuma Ichiro 
Published: July 2006

Abstract
Each of 5- or 6-amino-, acetamido-, hydroxy-, methoxy-, and chloroindazoles (including an unsubstituted one) and β NAD were subjected to an NADase-catalyzed base-exchange reaction to produce a corresponding title compound with a 41–76% yield. A difficulty, due to the poor solubility in water of indazole bases, was overcome by the addition of DMSO (∼20%) without a remarkable decrease in NADase activity. In most cases, the obtained dinucleotides were ascertained to be N2-ribosylated compounds. From 5- and 6-aminoindazoles, however, N1-ribosylated dinucleotide was also obtained as a minor product. In some of the N2-ribosylated dinucleotides, an unusual tautomerism was suggested to occur on the benzene ring of an indazole moiety. Finally, the synthesized title compounds were examined for inhibition activity against NAD-linked inosine monophosphate dehydrogenase. Four compounds among them were markedly effective at a 10−3 M concentration.
The Crystal and Molecular Structure of Two Triple-layered Metaparacyclophanes
Authors: Koizumi Yosuke , Toyoda Toshihiro , Kasai Nobutami , Misumi Soichi 
Published: July 2006

Abstract
Molecular structures of triple-layered metaparacyclophanes containing two and one para-bridged, outside benzene rings([2.2]paracyclo(4,6)[2.2]metaparacyclophane (PMP) and [2.2]metacyclo(4,6)[2.2]metaparacyclophane (MMP), respectively) have been determined by means of X-ray diffraction. PMP: monoclinic, space group P21/a, a=15.989(1), b=9.932(1), c=5.991(1) Å, β=100.61(1)°, Z=2. MMP: monoclinic, space group P21/c, a=8.969(2), b=22.774(4), c=10.339(2) Å, β=119.32(1)°, Z=4. The structure of PMP was solved by the vector search method and that of MMP by the direct method. They are refined anisotropically by the least-squares procedure, final R values are 0.066 for PMP and 0.096 for MMP. Of the two possible conformers PMP has a centrosymmetric staircase structure(anti-form) whereas MMP takes a platform shape(syn-form).
The Thermodynamic Behaviour of Nickel in a Molten LiF–KF–O2− System
Authors: Ito Yasuhiko , Hayashi Hidetaka , Itoh Yasuhiko , Yoshizawa Shiro 
Published: July 2006

Abstract
The thermodynamic behaviour of nickel in a molten LiF–KF–O2− system was investigated by using Pt(O2)/stabilized zirconia electrode as an oxide-ion-concentration indicator. The potentials of the Pt(O2)/stabilized zirconia/LiF–KF–O2− electrode and the Ni/NiO/LiF–KF–O2− electrode at 550 °C were measured as :
E=2.25−\fracRT2FlnX02−(V.vs.Li-K⁄Li+,K+)
and:
E=1.42−\fracRT2FlnX02−(V.vs.Li-K⁄Li+,K+)
respectively. The solubility product of NiO in the melt was thus determined to be Ksp=1.3×10−6 at 550 °C. With these results, a potential-pO2− diagram of the nickel in the system was presented.
Catalytic Epoxidation of Olefins with t-Butyl Hydroperoxide in the Presence of Polymer-supported Vanadium(V) and Molybdenum(VI) Complexes
Authors: Yokoyama Toshiro , Nishizawa Masato , Kimura Tetsuo , Suzuki Toshishige M 
Published: July 2006

Abstract
Oxovanadium(V) and oxomolybdenum(VI) ions have been incorporated into cross-linked polystyrene resins functionalized with iminodiacetic acid or diethylenetriamine derivatives. The polymer complexes have been used as catalysts in the epoxidation of olefins with t-butyl hydroperoxide. Vanadium(V) complexes promote epoxidation of allylic alcohols in a highly regioselective manner, e.g., 2,3-epoxide has been preferentially obtained in 98% selectivity from (E)-geraniol at 80 °C. The catalytic activity of the vanadium(V) complexes is generally higher than that of the molybdenum(VI) complexes in the epoxidation of allylic alcohols whereas an opposed trend holds for the epoxidation of cyclohexene. Life time of catalysts have been examined by repeated use of the complexes in the epoxidation of (E)-geraniol at 80 °C in benzene. Approximately 15–25% of vanadium has been leaked out of the polymer beads on five time recycles leading to the decrease in the yield of 2,3-epoxide from initial value of 98% to 95–93%. Neither appreciable loss of metal nor reduction of catalytic activity has been observed in the molybdenum complex systems over five runs.
Natural Homologs of Gramicidin S. II. Synthesis of Gramicidin S-2 and S-3
Authors: Nozaki Sukekatsu , Muramatsu Ichiro 
Published: July 2006

Abstract
Two cyclic dodecapeptides corresponding to newly found members of gramicidin S family, gramicidin S-2: cyclo(–Val–Orn–Leu–d-Phe–Pro–Abu–Orn–Leu–d-Phe–Pro–), and gramicidin S-3: cyclo(–Abu–Orn–Leu-d-Phe–Pro–Abu–Orn–Leu–d-Phe–Pro–), were synthesized. In the synthesis, the linear decapeptide precursors of the antibiotics prepared by a combination of the “hold-in-solution” method and the usual liquid phase method were converted to cyclic ones in excellent yields by one-pot reaction using 1-ethyl-3-(3-dimethylaminopropyl)carbo-diimide hydrochloride and 1-hydroxybenzotriazole. The synthesized antibiotics were identical with the natural products in HPLC analysis and assays of the antibiotic activities. The proposed structures for gramicidin S-2 and S-3 were confirmed. The CD spectra showed that the ring conformations of gramicidin S-2 and S-3 closely resemble each other and also that of gramicidin S-1, which has the already known structure.
Improved Synthesis and Crystal Structure of 7H-Dibenz[a,kl]anthracen-7-one
Authors: Fujisawa Shoji , Oonishi Isao , Aoki Junji , Ohashi Yuji , Sasada Yoshio 
Published: July 2006

Abstract
An improved synthetic method gives pure 7H-dibenz[a,kl]anthracen-7-one, C21H12O, in a higher yield than those reported so far. The crystal structure has been determined by X-ray analysis. The space group is Pn21a, with unit cell dimensions of a=23.325(5), b=14.149(3), c=3.986(1) Å, and Z=4. The structure was solved by the direct method and refined by the block-diagonal least-squares method to an R value of 0.044. The molecule is greatly distorted from the planar conformation because of an intramolecular steric repulsion between the hydrogen atoms.
Preparation of (l-Cysteinato)(l- or d-histidinato)chromium(III) Complex
Authors: Odaka Yoshio , Hasegawa Yuichi , Watabe Masatoshi 
Published: July 2006

Abstract
Mixed-ligand chromium(III) complexes of the form [Cr(l-cys)(l-or d-his)] (l-cys=l-cysteinate and l-his=l-histidinate anions) were prepared. Isolated isomers of each complex were assigned structures on the basis of their high-speed liquid chromatograms and the distribution of the isomers.
The Electrochemical Cleavage of Carbon–Halogen Bonds of Haloferrocenes
Authors: Saji Tetsuo , Ito Naoyuki 
Published: July 2006

Abstract
The cyclic voltarmmetric studies for haloferrocenes, FcX (X=Cl, Br, and I), in etylene glycol dimethyl ether at −45 °C have been reported. The cyclic voltammogram and the absorption spectrum of the solution after the exhaustive controlled-potential reduction for the reduction step of haloferrocene show a quantitative formation of ferrocene and a cleavage of the carbon–halogen bond of haloferrocene.
UV Photoelectron Spectra of Peralkylated Catenates of Group 4B Elements (Silicon, Germanium, and Tin)
Authors: Mochida Kunio , Worley S D , Kochi J K 
Published: July 2006

Abstract
The low-energy photoelectron spectra (PES) of twelve peralkylated catenates of group 4B elements (silicon, germanium, and tin) were recorded. The trends in the energies and the nature of the metal–metal and metal–carbon bonds are discussed.
Convenient Synthesis of β-Truxinic Acid via Photodimerization of p-Nitrophenyl Cinnamate in the Crystalline State
Authors: Nishikubo Tadatomi , Takahashi Eiji , Miyaji Takatoshi , Iizawa Takashi 
Published: July 2006

Abstract
β-Truxinic acid was synthesized in extremely high yield via a topochemical photodimerization of p-nitrophenyl cinnamate crystals, followed by the hydrolysis of the obtained dimer.
The Total Synthesis of (15R)- and (15S)-16-Hydroxyferruginol
Authors: Matsumoto Takashi , Imai Sachihiko , Miuchi Shigekazu , Sugibayashi Hidenori 
Published: July 2006

Abstract
In order to assign the absolute configuration of C-15 in natural 16-hydroxyferruginol, (5S,10S,15R)- (1a) and (5S,10S,15S)-8,11,13-abietatriene-12,16-diol (1b) have been synthesized. Optical resolution of 2-(2-methoxyphenyl)propanoic acid, prepared from methyl (2-methoxyphenyl)acetate, with cinchonidine afforded (R)- and (S)-enantiomers, which were converted into [(R)-4-methoxy-3-(2-methoxy-1-methylethyl)benzyl]triphenylphosphonium chloride (3a) and its (S)-isomer (3b) respectively. The Wittig reaction of (R)-(−)-α-cyclocitral with 3a, followed by partial catalytic hydrogenation and intramolecular cyclization gave (5S,10S, 15S)-12,16-dimethoxy-8,11,13-abietatriene (16a) together with its (5S,10R,15R)-isomer. Similarly, 3b was also converted into (5S,10S,15S)-12,16-dimethoxy-8,11,13-abietatriene (16b) and its (5S,10R,15S)-isomer. Demethylation of 16a gave 1a which was identical with natural 16-hydroxyferruginol. The dimethoxy compound 16b was also demethylated to give 1b.
Temperature Dependence of Walden Product of 18-Crown-6–K+ Complex in Water
Authors: Takeda Yasuyuki , Arima Osamu 
Published: July 2006

Abstract
Limiting ionic molar conductivities of the 18-crown-6–K+ complex in water were determined at 15 and 35 °C. Walden product values of the complex at 15, 25, and 35 °C are nearly identical within experimental errors of conductance measurements. Solvation properties of the complex in water were discussed in detail.
Comparison of the Excited-state Dipole Moments and Polarizabilities Estimated from Solvent Spectral Shifts with Those from Electrooptical Measurements
Authors: Abe Takehiro , Iweibo Idowu 
Published: July 2006

Abstract
On the assumption that the average energy for all transitions from a low-lying excited state to all other states was approximately the same as that for all transitions from the ground state to all excited states, Abe’s improved expression for the solvent spectral frequency shift (Bull. Chem. Soc. Jpn., 54, 327 (1981)) was applied to spectral data for some neutral organic molecules in solution in order to estimate their excited-state dipole moments and polarizabilities. The changes in the dipole moments and/or polarizabilities of these molecules upon excitation were compared with those obtained from electrooptical measurements. Both methods give results that are consistent.
Photoionization Study of the Sulfur Monoxide Radical Produced by Pyrolysis of Ethylene Sulfoxide
Authors: Nishitani Eisuke , Fukuda Kenichi , Tanaka Ikuzo 
Published: July 2006

Abstract
Sulfur monoxide (SO) radical has been produced in the gas phase by pyrolysis of ethylene sulfoxide (C2H4=SO) at 510 °C. The vacuum ultraviolet photoionization efficiency curve between 915 and 1220 Å has been obtained for the first time. Several thermodynamic data about C2H4=SO have also been obtained from direct photoionization. The values of the bond energies of D0(C2H4=SO) and D0(C2H4=SO+) are 4640±30 and 5160±30 cm−1 respectively. Ionization potentials (IP) of the SO(X3Σ−) radical and C2H4=SO, and the appearance potential (AP) of SO+ fragment ion from C2H4=SO are 10.28±0.01, 9.49±0.02, and 10.13±0.01 eV. In the system of C2H4=SO, the AP is lower than the IP and this phenomenon has only been found in this system.
Photolytic Generation and the Subsequent Dimerization of 4-Alkyl-1-methylpyridinyl Radicals in Solution as Studied by Steady-state and Kinetic ESR Spectroscopy
Authors: Akiyama Kimio , Ishii Toru , Tero-Kubota Shozo , Ikegami Yusaku 
Published: July 2006

Abstract
1-Methylpyridinyl and 4-alkyl-1-methylpyridinyl (alkyl=methyl, ethyl, isopropyl, and t-butyl) radicals were generated photolytically from their dimers in solution. Hyperfine splitting constants for these radicals were assigned and the temperature dependence was discussed. Absolute dimerization rates of these radicals in the range of −50–−100 °C were determined by analyzing the ESR signal decay during the dark period. A nearly constant activation energy of dimerization was observed for five radicals, while the frequency factor decreased with the bulkiness of 4-substituent, which are discussed in terms of the steric hindrance for the dimerization.
exo-Selective Peripheral Cycloaddition Reactions of Pyrido[2,1-a]isoindole
Authors: Kajigaeshi Shoji , Mori Seiji , Fujisaki Shizuo , Kanemasa Shuji 
Published: July 2006

Abstract
Pyrido[2,1-a]isoindole cycloadds to olefinic dipolarophiles in a highly exo-selective fashion giving the kinetically controlled cycloadducts which gradually isomerize into the Michael adducts. With acetylenic dipolarophiles, the hydrogen-migrated cycloadducts are the only products. The mechanism of cycloadditions is discussed.
Excess Volume of Mixing of Quaternary Phosphonium Chlorides with Potassium Chloride in Water
Authors: Takaizumi Katsuko , Wakabayashi Toshiki 
Published: July 2006

Abstract
Volume changes upon mixing aqueous solutions of potassium chloride and the quaternary phosphonium chloride, n·Bu4−nPhnPCl, (n=0–4), have been measured at various constant total ionic strengths (I=0.25, 0.5, 1.0) at 25 °C. Based on Friedman’s theory for a mixed electrolyte solution, volume-interaction parameters, υo, were determined at each ionic strength. The dependence of υo on I shows that contributions to the excess volume due to structural effects of a pairwise interaction between the cations and triplet interactions including a single anion are most significant for the Bu4P+ ion and decrease with increasing n. A comparison of the υo’s with the excess-volume properties of the salts in each pure solution shows that the interaction between the phosphonium cations and the potassium ion results in negative contributions to the excess volume of mixing, which also decreases as n increases.
A Straightforward Access to 5-Deoxy-d-arabinono-1,4-lactone, a Versatile Intermediate in the Lauraceae Lactones Syntheses
Authors: Torii Sigeru , Inokuchi Tsutomu , Masatsugu Yoshinori 
Published: July 2006

Abstract
5-Deoxy-d-arabinono-1,4-lactone (2) was synthesized by a RuO4-catalyzed oxidative cleavage of 6-deoxyglucal diacetate (5d), derived from d-glucal triacetate (3), followed by alkaline hydrolysis and acidic work-up.
A Common Factor Determining the Features of the Photocatalytic Hydrogenation and Isomerization of Alkenes over Ti–Si Oxides
Authors: Kodama Sukeya , Nakaya Hiroaki , Anpo Masakazu , Kubokawa Yutaka 
Published: July 2006

Abstract
On addition of SiO2 to TiO2 photocatalysts, it has been found that the yields of C2H6 and CH4 in the photocatalytic hydrogenation of propylene as well as that of 1-butene in the photocatalytic isomerization of cis-2-butene decrease simultaneously. This gives some support for the mechanisms for both reactions where [Ti3+–O−] pairs are important.
The Microwave Spectrum of (Z)-(Acrylaldehyde Oxime)
Authors: Terashima Mariko , Ohashi Osamu 
Published: July 2006

Abstract
The microwave spectrum of (Z)-(acrylaldehyde oxime) was observed in the frequency region from 10 to 40 GHz.
Several a-type R-branch transitions in the ground vibrational state were identified and the rotational constants in MHz were determined to be A=17430.7(35), B=3022.514(15), and C=2576.504(16). The conformation of (Z)-(acrylaldehyde oxime) has been plausibly deduced to be the s-trans Z-form from the rotational constants experimentally determined. The angle of C–C=N is discussed.
Atomic Absorption Spectrophotometric Determination of Cadmium
Authors: Kabil Mohamed A , Mostafa Mohamed A 
Published: July 2006

Abstract
In the determination of cadmium by atomic absorption spectrophotometry(AAS), the interfering effects of different species can be completely eliminated by adding excess cyanide. The mechanism by which the cyanide eliminates interference by influencing the atomization process is discussed. Also the AAS for the analysis of cadmium in complex form is elaborated. The aim of this investigation is to achieve a determinate characterization of compound formation. The way to reach this purpose is the utilization of the continuous titration technique.
1,8-Diazabicyclo[5.4.0]undec-7-ene. An Effective and Selective Catalyst for the t-Butyldimethylsilylation of Alcohols
Authors: Kim Sunggak , Chang Heung 
Published: July 2006

Abstract
The use of 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst has been found to be very effective and selective in the t-butyldimethylsilylation of primary and secondary alcohols.
Mechanochemical Changes of Neodymium Phosphates by Grinding
Authors: Nariai Hiroyuki , Motooka Itaru , Doi Mayumi , Tsuhako Mitsutomo 
Published: July 2006

Abstract
The effect of mechanochemical treatment on some neodymium phosphates was investigated. It is worth noting that on mechanochemical treatment NdPO4·0.5H2O (hexagonal) is gradually transformed into NdPC4 (monoclinic) at room temperature, while thermal change of NdPO4·0.5H2O to NdPO4 (monoclinic) happens at above 600 °C. Condensed phosphates, meta- and ultraphosphates, easily turned to X-ray amorphous structure by grinding.
New Synthesis of trans-γ-Irone
Authors: Takazawa Osamu , Kogami Kunio , Hayashi Kazuo 
Published: July 2006

Abstract
trans-γ-Irone was successfully synthesized starting from 3,4-dimethyl-2-cyclohexenone by sevenstep reactions including TiCl4-promoted reaction of enol silyl ether and cross-aldol reaction of vinyloxyborane.
A New Synthetic Model for Myoglobin: “Tulip Garden” Porphyrin
Authors: Takagi Shigeru , Miyamoto T Ken , Sasaki Yukiyoshi 
Published: July 2006

Abstract
A new model compound “tulip garden” porphyrin, has a long half-lifetime, thus satisfying the demand for the synthetic analogue of myoglobin. At the same time, “tulip garden” porphyrin has high O2 affinities as compared to other protected porphyrins; especially, its Co(II) complex shows almost the same affinity (P1/2O2) as coboglobins. The difference in oxygen affinities between “tulip garden” and “picket fence-type” porphyrins can be ascribed to the bulkiness of pendant groups. The strong “side” influence of the adamantyl group can be expected to bring about a high O2 affinity.