bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Phase Peptide Synthesis by the Fragment Condensation on Soluble Polymer Support. I. Efficient Coupling and Relative Reactivity of a Peptide Fragment with Various Coupling Reagents
Authors: Narita Mitsuaki 
Published: July 2006

Abstract
The fragment condensation on the soluble polymer support using dicyclohexylcarbodiimide (DCCI) plus 1-hydroxy-1H-benzotriazole (HOBt), diethoxyphosphoryl cyanide (DEPC), and triphenylphosphine (Ph3P) plus di-2-pyridyl disulfide ((PyS)2) as coupling reagents gave rise to efficient coupling (86–99% yield) of the peptide fragment, t-butyloxycarbonyl-l-O-benzyl-tyrosylglycylglycyl-l-phenylalanine [Boc-l-Tyr(Bzl)–Gly–Gly–l-Phe–OH], to the amino free terminal of Leu anchored to the soluble polymer support, H–l-Leu–OCH2–resin. Relative reactivity ratios of Boc–amino acids and Boc–l-Tyr(Bzl)–Gly–Gly-l-Phe–OH with H–l-Leu–OCH2–resin in the coupling reaction using the three coupling reagent systems could be easily determined by use of amino acid ratios in the acid hydrolysates of the resulting peptide resins in which they were taken. The peptide chain length of Boc–l-Tyr(Bzl)–Gly–Gly–l-Phe–OH has no influence on the reactivity of C-terminal amino acid in the coupling reaction using DCCI plus HOBt or DEPC as a coupling reagent when Boc–l-Phe–OH was replaced with Boc–l-Tyr(Bzl)–Gly–Gly–l-Phe–OH. The coupling reagent, Ph3P plus (PyS)2, brought about a marked decrease in the reactivity of the fragment peptide acid.
The Reaction of 1,3,5-Triazine with Aromatic Nitrile Oxides. A New Synthesis of 3-Substituted 1,2,4-Oxadiazoles
Authors: Kurabayashi Masahiro , Grundmann Christoph 
Published: July 2006

Abstract
The cycloaddition of aromatic nitrile oxides(2a=benzo-; 2b=p-tolu-; 2c=mesitylenecarbo-) with 1,3,5-triazine(1) is reported. The corresponding 3-substituted 1,2,4-oxadiazoles(3a,b,c) are obtained in fair yields only when BF3 is added. It was stoichiometrically confirmed that one mol of 1 behaves so as to supply three mols of azomethine radicals. A reaction scheme initiated from a two-step cycloaddition of 2 to 1 activated by BF3 is suggested. The mixture, 1 : 2c : BF3=1 : 3 : 1, afforded a better yield of 3c(69%) than an equimolar mixture of 2c with ethyl formimidate or formamidine.
Reactions of Aromatic Compounds in Molten Salts. II. The Rearrangement of Phenylhydrazine to Give o-Phenylenediamine in a Molten Mixture of AlCl3–NaCl–KCl
Authors: Imaizumi Hisao , Hashida Yoji , Matsui Kohji 
Published: July 2006

Abstract
Phenylhydrazine gave o-phenylenediamines as the major product upon heating in a molten mixture of AlCl3–NaCl–KCl. In the molten mixture, some aromatic compounds gave the corresponding aromatic amines in good yields in the presence of phenylhydrazine, suggesting that the method provides a novel direct process for the preparation of aromatic amines.
Investigation on the Lanthanoid Chelates of 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone. An Examination of the Phenomenon of Hypersensitivity
Authors: Roy Ajoy , Nag K 
Published: July 2006

Abstract
1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone (Hpmbp) form complexes with lanthanoids of the type Ln(pmbp)3· nH2O (n=4 for La–Sm, and n=1 for Eu–Yb and Y), Ln(pmbp)3·2pyridine·2H2O, Ln(pmbp)3·(2,2′-bipyridine/1,10-phenanthroline)·C2H5OH, NH4[Ln(pmbp)4]·C2H5OH and Q+[Ln(pmbp)4]·C2H5OH, where Q+ is the quaternary ammonium cation of piperidine, pyrrolidine or morpholine. These compounds have been characterized from physicochemical studies. The electronic spectra of the Nd(III) complexes have been studied in detail to investigate the phenomenon of hypersensitivity with respect to the coordination environment and solvent medium. In these compounds solvent does not play a significant role to cause variation in hypersensitivity. The oscillator strengths of the hypersensitive transition in these compounds show the following trend: Q+[Nd(pmbp)4]&gt;Nd(pmbp)3·phen&gt;Nd(pmbp)3·bpy&gt;Nd(pmbp)3·2py·2H2O&gt;Nd(pmbp)3·2H2O. In the Pr(III) complexes the band due to 3H4→1D2 transition has been found to be hypersensitive, and the gradation of intensity due to this band follows almost the same trend as in the corresponding Nd(III) complexes.
Effect of Monohydroxy Alcohols and Urea on the CMC of Surfactants
Authors: Singh H N , Swarup Shanti 
Published: July 2006

Abstract
The effect of monohydroxy alcohols on the critical micelle concentration (CMC) of anionic and cationic surfactants have been studied by a conductometric method. The CMC was found to decrease by adding small quantities of alcohol and raised again at higher alcohol concentrations. The CMC decreasing effect has been discussed on the basis of more ordered water cavity formed around the added alcohol molecules and their increasing effect by the partition of alcohol between the micellar and the bulk phase leading to the break-down of the micelles. The effect of urea on CMC in alcohol–water mixtures has been studied and its CMC increasing effect explained.
Studies on Spontaneous Emulsification. III. Molecular Interaction at the Oil–Water Interface
Authors: Ogino Keizo , Umetsu Hidetoshi 
Published: July 2006

Abstract
At the oil–water interface, measurements of the interfacial tension were performed simultaneously with the observation of spontaneous emulsification. The effects of an oil-soluble alcohol (1-dodecanol) and a water-soluble surfactant (SDS) on the interfacial tension and on the spontaneous emulsification were studied.
Complex Anion Radical Salts Derived from Dicyanomethylenetrinitrofluorene
Authors: Matsunaga Yoshio , Yoshida Yuji 
Published: July 2006

Abstract
Four anion radical salts of the 2 : 3 type were derived from 9-dicyanomethylene-2,4,7-trinitrofluorene. Their electronic spectra, the ESR spectra characteristic of triplet excitons, and the electrical properties were measured.
Spectroscopic Similarity of Charge-Transfer Absorptions in Crystalline Complex Ion Radical Salts
Authors: Iida Yôichi 
Published: July 2006

Abstract
Charge-transfer transition between ion radical molecules takes place in crystalline ion radical salts. Spectroscopic similarity of the charge-transfer absorptions between certain systems of complex ion radical salts has been studied with use of a one-dimensional Hubbard model.
Solvolysis in Carboxamides. III. Solvolysis Rates of 1-Adamantyl Bromide and Tosylate, 2-Adamantyl Tosylate, and t-Butyl Chloride in Carboxamides
Authors: Saito Seiki , Doihara Kenji , Moriwake Toshio , Okamoto Kunio 
Published: July 2006

Abstract
Rate constants for the solvolysis of 1-adamantyl bromide and tosylate, 2-adamantyl tosylate, and t-butyl chloride in the four carboxamide solvents, i. e., N,N-dimethylacetamide, N,N-dimethylformamide, N-methylacetamide, and N-methylformamide, have been determined. The role of the carboxamides as solvolytic solvents has been discussed on the basis of linear free-energy relationship.
Effect of Hydration on the Thermal Denaturation of Lysozyme as Measured by Differential Scanning Calorimetry
Authors: Fujita Yukihisa , Noda Yukinao 
Published: July 2006

Abstract
The thermal properties of the lysozyme-water system were investigated by differential scanning calorimetry under varied water contents, ranging from 0.05 to 1.6 g per g of protein. The temperature, Td, and the enthalpy change, ΔHd of denaturation at water contents below 0.75 g/g showed strong dependencies on the hydration. At higher water contents, however, Td and ΔHd were almost independent of the degree of hydration, showing values almost identical to those in solution.
Studies on Heterocyclic Analogs of Azulenes. IV. Behavior of 2-Chlorocyclohepta[b]pyrrole Derivatives toward Phosphorus Ylide
Authors: Nishiwaki Tarozaemon , Abe Noritaka , Ishida Kozue , Miura Kaoru 
Published: July 2006

Abstract
The transylidation reaction of methyl(triphenylphosphoranylidene)acetate with 2-chlorocyclohepta[b]pyrrole derivatives has been studied. 3,8-Disubstituted derivatives gave a transylidation product only, whereas 3-substituted derivatives afforded not only a transylidation products but also the compounds formed by the addition of ylide at C-8. 13C NMR spectra of the transylidation products are recorded in part.
Studies on Aziridine-2-carboxylic Acid. I. Synthesis of the Optically Active l-Aziridine-2-carboxylic Acid and Its Derivatives
Authors: Nakajima Kiichiro , Takai Fumiko , Tanaka Takumi , Okawa Kenji 
Published: July 2006

Abstract
Lithium l-aziridine-2-carboxylate was synthesized from N-trityl-l-aziridine-carboxylic acid benzyl ester by the treatment with trifluoroacetic acid followed by the saponification with lithium hydroxide. Several N-acylaziridine-2-carboxylic acid esters were synthesized in good yield.
Defect Chemistry of Barium Monoferrite, BaFe2O4−δ
Authors: Nakamura Akio , Yamauchi Shigeru , Fueki Kazuo , Mukaibo Takashi 
Published: July 2006

Abstract
In order to obtain information on the defects in ternary oxide systems, the nonstoichiometry and electrical conductivity of BaFe2O4 were determined at temperatures between 1050 and 1125 °C. The electrical conductivity was found to be proportional to PO2−1⁄6. This relationship suggests that BaFe2O4 is an oxygen deficient n-type semiconductor at high temperatures. The nonstoichiometry was proportional to PO2−1⁄2.88. order to interpret the dependence of electrical conductivity and nonstoichiometry on the oxygen partial pressure, various defect models were examined. As a result the following equilibria were selected from among the oxygen vacancies V0·· and V0x, and oxygen gas.
null=(1⁄2)O2+V0x
V0x=V0··+2e′
An analysis based on the above defect model explains the data well.
The Molecular Structure of Ethyl Chloride as Determined by a Combined Use of the Electron-diffraction Data and the Spectroscopic Moments of Inertia
Authors: Hirota Masashi , Iijima Takao , Kimura Masao 
Published: July 2006

Abstract
The molecular structure of ethyl chloride has been determined by a joint analysis of the electron-diffraction data and the moments of inertia obtained by Schwendeman and Jacobs by means of microwave spectroscopy. In the analysis, a staggered conformation with Cs symmetry for the molecule and a local C3v symmetry about the C–C axis for the methyl group were assumed. Under the further assumptions that \varphiav(HCH)CH2 is 109.2±2° and \varphiav(CCH)CH2 is in the range of 113.6–109.6°, the following parameter values were determined: rg(C–C) 1.528(4) Å; rg(C–Cl), 1.802(3) Å; rg(C–CI), 2.746(5) Å; rg; rg(C–H)CH2, 1.103(4) Å; \varphiav(HCH)CH2, 110.0(1.6)°; and \varphiav(CCCl), 110.7(0.3) °. The rg and rs distances for the C–Cl and C-C bonds of various chlorinated alkanes were plotted against the difference between the numbers of methyl groups and chlorine atoms, Δn=n(CH3)–n(Cl). In general, as the number of chlorine atoms increases, both distances become shorter, though the rg distances are longer than the rs distances by 0.01–0.03 Å.
Minima in the Solubilities of Normal Alkane Derivatives with a Polar Group in Water
Authors: Nishino Nobuo , Nakamura Masao 
Published: July 2006

Abstract
The change in the solubility in water with the temperature was measured for alkanols, alkylamines, and alkanoic acids. It has been found that a minimum exists commonly on the solubility-temperature curve. This minimum dissolution point, Pm, may be regarded as a characteristic point with respect to the solute. The change in the solubility with the temperature has been explained in terms of the increase in the partial molar enthalpy of the solute in solution with an increase in the temperature, which results from the breakdown of the ice-like structure of water formed around the nonpolar alkyl group. Both the concentration, xm, and temperature, Tm, at point Pm decrease with an increase in the number of carbon atoms in the alkyl group, m. The decrease in In xm by the addition of one methylene group is steeper in the order of alkanoic acids, alkylamines, and alkanols, while the corresponding decrease in Tm shows the reverse order. In addition, Tm is related to the cohesive energy of the solute in the pure state.
Application of Microwave Spectroscopy to Kinetic Study of the Reaction of Carbonyl Sulfide with Atomic Oxygen
Authors: Yoshida Noritetsu , Saito Shuji 
Published: July 2006

Abstract
Microwave spectroscopy has been applied to the determination of the rate constant for OCS+O→SO+CO. A short cell of a parallel-plate type was devised for the detection of the SO radicals produced in a fast flow reactor. Production of the SO radical was traced by measuring its spectral line intensity under the condition of [OCS]&gt;&gt;[O]. The rate constant for the reaction was determined to be (7.1±0.7)×109 cm3/mol·s at room temperature (24–25) °C, in good agreement with the values obtained by other methods.
Determination of Micro Amounts of Polythionates. X. Spectrophotometric Determination of Micro Amounts of Pentathionate in Mixtures with Thiosulfate and Sulfite by Means of Its Sulfitolysis
Authors: Koh Tomozo , Taniguchi Kazuo , Iwasaki Iwaji 
Published: July 2006

Abstract
An accurate method has been proposed for the determination of pentathionate in mixtures with thiosulfate and sulfite. The method is based on the formation of thiosulfate equivalent to the pentathionate, and the spectrophotometric determination of excess iodine for the reaction with the thiosulfate formed. The conditions for pentathionate to be quantitatively converted into thiosulfate were established by varying pH, reaction time, and amounts of sulfite. The method can be successfully applied to the determination of pentathionate, thiosulfate, and sulfite when they are mixed in various ratios, giving a relative standard deviation of 0.82% at the 0.5 μmol level of pentathionate in a 10.0 cm3 sample solution in the presence of 0.5 μmol of thiosulfate and 0.25 μmol of sulfite.
The Application of a Quadrupole Mass Spectrometer to a Study of Methane Oxidation in Shock Waves
Authors: Hidaka Yoshiaki , Nagayama Midori , Suga Masao 
Published: July 2006

Abstract
A part of the mass-spectrometer shock-tube apparatus was improved, and its working characteristics were examined. The oxidation of methane was studied with this apparatus over the temperature range of 1800–2500 K and the total pressure range of 360–560 Torr at O2/CH4 ratios of 1–3. The induction period was measured by monitoring the oxygen concentration, and the following equation was found to hold:
τ=4.54×10−10[CH4]0.37[O2]−0.64exp(35600⁄RT) s
in which the concentrations were expressed in mol per cubic centimeter.
Molecular Dissociation of 3-Cyclopenten-1-one Photosensitized by Excited Mercury (3P1)
Authors: Nakamura Kazumoto , Koda Seiichro , Akita Kazuo 
Published: July 2006

Abstract
The mercury photosensitized decomposition of 3-cyclopenten-1-one produced carbon monoxide and 1,3-butadiene in equal quantum yields as the exclusive products, independent on the absence or presence of nitrogen oxide. Thus the process was a molecular dissociation. The quantum yield was dependent on the pressure of argon added as a third body and revealed a maximum at the pressure of about 100 mmHg. A possible reaction scheme was proposed to explain the above kinetic behavior. It was suggested that the vibrationally excited state of 3-cyclopenten-1-one was a main precursor to decompose to carbon monoxide and 1,3-butadiene. An energy about 20 kcal·mol−1 was estimated to be lost before its production from the original triplet state 3-cyclopenten-1-one according to the proposed reaction scheme. This result is compared with the behaviors of excited 3-cyclopenten-1-ones produced by different excitation procedures.
Luminescence Properties and the Primary Process of Photochromism of 2-(2-Hydroxyphenyl)benzothiazole
Authors: Nakagaki Ryoichi , Kobayashi Takayoshi , Nagakura Saburo 
Published: July 2006

Abstract
The luminescence behavior of 2-(2-hydroxyphenyl)benzothiazole at 77 K was studied in detail, special attention being paid to dual fluorescence at ≈500 and ≈370 nm and also to phosphorescence at ≈500 nm. From the dependence of these emission bands upon the hydrogen-bonding ability of solvents and the excitation spectra, it is concluded that the short- and long-wavelength fluorescence bands are due to the intermolecularly hydrogen-bonded enol imine and the keto amine produced from the intramolecularly hydrogen-bonded enol, respectively, and that the phosphorescence is due to the intermolecularly hydrogen-bonded enol imine. The estimated quantum yield of the enol fluorescence gives further support to the formation scheme of the photochromic colored species previously presented. The rate constants of the intramolecular hydrogen transfer at 77 and 293 K are evaluated to be larger than 4×1010 s−1 and 3×1012 s−1, respectively.
Heterogeneous Catalysis in Liquid-Phase Oxidation of Olefin. II. Dependence of the Structure of Vanadium–Chromium Binary Oxide Catalyst for Oxidation of Cyclohexene on the Method of Preparation
Authors: Takehira Katsuomi , Hayakawa Takashi , Ishikawa Toshio 
Published: July 2006

Abstract
The influence of preparative conditions on the structure and catalytic activity of V–Cr oxide catalyst for the liquid-phase oxidation of cyclohexene has been investigated. Three series of binary oxide, V–Cr-D, V–Cr-E, and V–Cr-F, were prepared from acidic, neutral, and alkaline media, respectively. The specific activity of the catalyst was found to be in the order: V–Cr-D&gt;V–Cr-E&gt;V–Cr-F, the catalyst prepared from acidic medium showing the highest activity. The results of structure analysis showed the formation of several chromium isopolyvanadates, i.e., chromium pyrovanadate, chromium metavanadate, and unknown phase (probably chromium polyvanadates), together with V2O5, Cr2O3, and solid solution of Cr6+ in V2O5 lattice. The formation of chromium isopolyvanadate having a higher degree of condensation of the vanadate anion was promoted by use of a more acidic medium in the catalyst preparation. The higher activity for autoxidation was obtained with the catalyst containing the more condensed isopolyvanadate. Epoxidation seems to proceed by the hydroperoxide intermediate mechanism on the active site differing from that for autoxidation.
Interactions of Calcium Ions with Carbohydrates: Crystal Structure of Calcium Dl-Glycerate Dihydrate
Authors: Taga Tooru , Ohashi Makoto , Osaki Kenji 
Published: July 2006

Abstract
The crystal structure of calcium Dl-glycerate dihydrate has been determined by the heavy atom method. The crystal is monoclinic, space group P21/c, with unit cell dimensions: a=14.40, b=7.63, c=10.40 Å, and β=98.8°. Two independent glycerate anions have different conformations. β-Hydroxy oxygen in one conformer is trans-gauche to α-carboxy carbon and α-hydroxy oxygen, while that in the other conformer is gauche-gauche. Ca–O interactions and hydrogen bonds stabilize the crystal structure. The calcium ion is bound to three glycerate anions and two water molecules, the two glycerate anions chelating the calcium ion with the α-carboxy oxygen and α-hydroxy oxygen, and third glycerate anion bonding to the calcium ion with β-hydroxy oxygen. Seven oxygens surround a calcium ion in a distorted pentagonal biprism arrangement with Ca–O distances ranging from 2.32 to 2.47 Å.
Abnormal Hyperchromism of the n→π* Absorption Band of Acetone in Protic Solvents
Authors: Yudasaka Masako , Hosoya Haruo 
Published: July 2006

Abstract
Concentration dependence (1–10−4 molar fraction) of the UV absorption spectra of the binary mixtures of (i) acetone–water, (ii) acetone–ethanol, and (iii) diisobutyl ketone–ethanol systems was studied. In (i) and (ii) distinct spectral changes of three steps were observed in succession, while in (iii) gradual changes in two steps were observed. The intensities of the n→π* band of very dilute solutions for these systems are enhanced, respectively, by 40, 20, and 15 per cent. The results were interpreted as the following stepwise equilibria
A+B\ightleftarrowsAB, AB+B\ightleftarrowsAB2, AB2+B\ightleftarrowsAB3
for (i) and (ii), while in (iii) the last step is obscured, where A and B denote, respectively, ketone and water or ethanol molecules. The structure of AB3 is discussed.
Bivalent and Tervalent Cobalt Complexes of 4-(2-Pyridylazo)resorcinol, 1-(2-Pyridylazo)-2-naphthol, and their Thiazolyl Analogs in Aqueous and Aqueous Dioxane Media. Rapid-scan Spectral and Kinetic Studies
Authors: Mochizuki Katsura , Imamura Taira , Ito Tasuku , Fujimoto Masatoshi 
Published: July 2006

Abstract
The reactions of Co2+ with 4-(2-pyridylazo)resorcinol (PAR), 1-(2-pyridylazo)-2-naphthol (PAN), and their thiazolyl analogs TAR and TAN in aqueous or aqueous dioxane media are followed by a rapid-scan spectroscopic method combined with stopped-flow technique. The step of the fast formation of cobalt(II) complexes is clearly discriminated from the subsequent slower step of oxidation to the cobalt(III) state. Formation and redissolution of transient insoluble intermediates are observed in the stopped-flow signals for the light scattered by the reaction mixture. The metal-to-ligand ratio in the short-lived intermediate cobalt(II) complex of PAR and PAN is determined to be 1 : 2 by applying the method of continuous variation to the fast change in stopped-flow signals. The rate constants k1 and k2 for the step of formation of 1 : 1 cobalt(II) complex with the species LHH* and LH− of PAR in aqueous solution and with the species LH2+ and LH of PAN in 5%(v/v) dioxane-water are determined to be k1=4.8×104 and k2=9.8×104 dm3 mol−1 s−1, and k1&lt;103 and k2=4.6×103 dm3 mol−1 s−1, respectively.
Synthesis of Oxide-Chalcogenides. I. Hydrothermal Synthesis of Sarabauite CaSb10O10S6 and Related Compounds
Authors: Nagashima Kozo , Ogino Masataka , Nakai Izumi 
Published: July 2006

Abstract
Single crystals of a recently described metal oxide sulfide mineral sarabauite and three related oxide-sulfides of alkaline earths and antimony were hydrothermally synthesized. (1) CaSb10O10S6: color, carmine red; crystal system, monoclinic; space group, C2/c. (2) Compound in Sr–Sb–O–S system (O&lt;S), blackish silver, monoclinic, P21/a. (3) Compound in Ba-S–b–O–S system (O&gt;S), reddish orange, triclinic P1 or P\bar1. (4) Compound in Ba–Sb–S–O system (O&lt;S), blackish brown, monoclinic, P21/a.
Synthesis and Spectroscopy of Acetato and Dithiocarbamate Complexes of Bis(cyclopentadienyl)zirconium(IV)
Authors: Suzuki Hideo , Takiguchi Toshio , Kawasaki Yoshikane 
Published: July 2006

Abstract
Several acetato and dithiocarbamate complexes of bis(cyclopentadienyl)zirconium(IV), Cp2Zr(X)OAc (X= Me, Cl, OAc), Cp2Zr(X)dmtc (X=Me, Cl; dmtc=S2CNMe2), and Cp2Zr(X)detc (X=Me, Cl; detc=S2CNEt2) have been prepared. Infrared, 1H NMR and mass spectra of these complexes suggest the chelation of acetato (except for one acetato group in Cp2Zr(OAc)2) and dithiocarbamate groups, affording 18-electron configuration of the zirconium atom. The infrared spectrum of diacetate bis(cyclopentadienyl)zirconium(IV) shows that one acetato group acts as bidentate ligand and the other as unidentate. Remarkable benzene- and hexafluorobenzeneinduced shifts were observed in the 1H NMR signal of methyl group attached to the zirconium atom and the dithiocarbamate group.