bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Highly Stereoselective Reduction of Substituted Cyclohexanones Using Triisobutylaluminum–Amine Complexes
Authors: Suzuki Toshimitsu , Itoh Maki , Ogawa Shigeyuki , Takegami Yoshinobu 
Published: July 2006

Abstract
The stereochemistry of the reduction of substituted cyclohexanones with a triisobutylaluminum(TIBA)–amine complex has been investigated, and the origin of the stereoselectivity has been discussed. Although a reduction of 4-t-butylcyclohexanone with free TIBA at 60 °C gave 83% trans alcohol, with a high stereoselectivity, 91–98% trans alcohol was obtained in this study. In order to discuss the reactivity of the reagent, the mode of the complexing of an amine to TIBA was investigated by infrared and NMR spectroscopy.
General Synthesis of Phosphonates from Heteroniaanthracene Cations and Their Use in Wittig-Horner Reaction
Authors: Ishikawa Kiyofumi , Akiba Kin-ya , Inamoto Naoki 
Published: July 2006

Abstract
Heteroaromatic cations such as 9-heteroniaanthracene (acridinium, xanthylium, and thioxanthylium) and 1-thionianaphthalene (thiochromenylium) ions reacted with trimethyl phosphite in the presence of sodium iodide in acetonitrile at room temperature to give the corresponding phosphonates (2 and 4) respectively in 76–92% yields. The phosphonates were deprotonated with butyllithium in THF at −78 °C, and the resulting carbanions reacted with p-tolualdehyde, cinnamaldehyde, and 4,4′-dichlorobenzophenone to afford the corresponding exomethylene containing heterocyclic compounds, respectively, in 52–96% yields. However, the phosphonate carbanions derived from 2 did not react with cycloalkanones and butanal.
Preparation of D:B-Friedoolean-5(10)-en-1-one and Related Compounds. A Comment on the Structure of “Glut-5(10)-en-1-one” from Euphorbia Nerifolia
Authors: Akiyama Eri , Moriyama Yoshihiko , Murae Tatsushi , Tsuyuki Takahiko , Takahashi Takeyoshi 
Published: July 2006

Abstract
In order to examine the structure, “glut-5(10)-en-1-one”, proposed for a new triterpene from Euphorbia nerifolia, this ketone (≡ D : B-friedoolean-5(10)en-1-one) was prepared. Oxidation of D : B-friedoolean-5(10)-ene with chromium trioxide-pyridine complex gave the allylic oxidation products, D : B-friedoolean-5(10)-en-1-one, D : B-friedoolean-5(10)-en-6-one, and D : B-friedoolean-5(10)-ene-1,6-dione. The spectral data and physical constants of the synthetic ketone (D : B-friedoolean-5(10)-en-1-one) were not identical with those of the new triterpene; this requires revision of the structure of this natural triterpene. Oxidation of D : B-friedoolean-5(10)-en-3-one enol acetate under the same conditions to give D : B-friedooleane-1,5(10)-dien-3-one is also described.
Peptide Syntheses with Proteinases. Fragment Condensation of ZLeuGlnGlyOH or ZGlnGlyOH with HLeuValNH2 Using Metalloproteinases
Authors: Isowa Yoshikazu , Ichikawa Tetsuya , Ohmori Muneki 
Published: July 2006

Abstract
The crude preparations of microbial metalloproteinase from Bacillus subtilis var. amyloliquefaciens (Prolisin) catalyzed the condensation of ZLeuGlnGlyOH or ZGlnGlyOH with HLeuValNH2 in the presence of the serineproteinase inhibitor from potatoes to give the corresponding Z-penta or tetra-peptide amide in good yields in an aqueous buffer solution. Two other metalloproteinases, from Bacillus thermoproteoliticus (Thermolysin or Thermoase) and Streptomyces caespitosus (Tacynase N), also catalyzed this reaction; however, they gave poorer results than Prolisin. The yields of the coupling products were affected most by the concentration of the substrates, among the several factors investigated. Addition of a small amount of an organic solvent sometimes promoted the yield for this method.
Studies in Isodielectric Media. The Standard Potentials of Ag–AgCl and Ag-AgBr Electrodes in 1,2-Ethanediol-2,2′-Oxydiethanol Mixtures at 25 °C
Authors: Sivaprasad P , Kalidas C 
Published: July 2006

Abstract
Standard potentials of Ag-AgCl and Ag-AgBr electrodes in various compositions of 1,2-ethanediol-2,2′-oxydiethanol (ethylene glycol-diethylene glycol) mixtures at 25 °C are reported. The free energies of transfer of the hydrogen halides from ethylene glycol to the mixtures were evaluated on mole fraction scale. The transfer free energies of H+ and the halide ions were determined employing the ferrocene reference method. The results suggest that the basicity of the mixtures increases with the addition of diethylene glycol and that it is more basic than ethylene glycol.
The Preparation of 2,2′-Bipyridinedicarbonato and Dicarbonato-1,10-phenanthroline Complexes of Cobalt(III)
Authors: Ida Yayoi , Imai Kiyoyuki , Shibata Muraji 
Published: July 2006

Abstract
Two new dicarbonato complexes, K[Co(CO3)2(bpy)]·2H2O and K[Co(CO3)2(phen)]·H2O, have been prepared by the method starting from the [Co(Co3)3]3− complex and resolved by means of diastereoisomer formation.
Cyclopentadienyl- and Pentamethylcyclopentadienylbis(isocyanide)cobalt(I)
Authors: Yamamoto Yasuhiro , Mise Takaya , Yamazaki Hiroshi 
Published: July 2006

Abstract
Compounds, η-C5H5Co(RNC)2 and η-Me5C5Co(RNC)2 were prepared from Co2(RNC)8 and C5R5H (R=H, CH3), and from η-C5H5Co(CO)2 and isocyanide.
Synthesis of 5-(Substituted methyl)-6,8-dimethyl-4-chromanones
Authors: Ninagawa Akira , Matsuda Haruo 
Published: July 2006

Abstract
5-(Substituted methyl)-6,8-dimethyl-4-chromanones were synthesized from the reactions of 5-hydroxymethyl-6,8-dimethyl-4-chromanone with nucleophilic reagents in acid media, and the reactions of its 5-halomethyl derivatives with ethoxide or phenoxide nucleophiles.
Interaction of Synthetic Polypeptides with Lipids in Monolayers
Authors: Yamashita Takuya , Shibata Akira , Yamashita Shinsuke 
Published: July 2006

Abstract
The interaction of polypeptide (benzyloxycarbonyl derivatives of basic poly(γ-amino acid), benzyl esters of acidic poly(α-amino acid), and poly(l-leucine)) and lipid (fatty acids, fatty alcohols and cholesterol) at the air–water interface was investigated. From the additivity rule of mean molecular areas and the work of collapse of the monolayers, it was found that the characteristic interaction occurs in the polymer rich region (less than 0.2 lipid mol fraction), and that the interaction is stronger for the polymer with higher helical content. The interaction was found to take place between side chains of polypeptides and lipids, and to be mainly of hydrophobic nature. The components in mixed polypeptide–cholesterol monolayers exhibit characteristic miscibilities depending upon the chemical composition of polymer side chains. The polarized infrared spectra of collapsed films consisting of single or mixed components indicate that the polymer component is aligned in a direction parallel to the compressing barrier.
The Ullmann Condensation Reaction of Haloanthraquinoiie Derivatives with Amines in Aprotic Solvents. III. The Formation and Role of Copper(II) Species in the Condensation with 2-Aminoethanol by Copper(I) Catalyst
Authors: Arai Sadao , Hida Mitsuhiko , Yamagishi Takamichi 
Published: July 2006

Abstract
The ESR spectra of the Ullmann condensation reaction system of 1-bromoanthraquinone-2-aminoethanol-CuBr showed that copper(II) species and 1-bromoanthraquinone radical anion were formed by an electron transfer from copper(I) species to 1-bromoanthraquinone. Although copper(II) species alone had little catalytic activity, the resulting copper(II) species increased the catalytic activity of the copper(I) species, and a pseudo-first order rate constant could be expressed as follows: k=k1[CuI]+k2[CuI][CuII]. According to the magnitude of k1 and k2C0, where C0 is the initial concentration of copper(I) catalyst, the reaction of haloanthraquinone with 2-aminoethanol by copper(I) catalyst can be classified into three modes. When k1&lt;k2C0, an induction period is present. The possible mechanisms of the cooperation between copper(I) and copper(II) species have been proposed. It has been also found that 1-bromoanthraquinone radical anion was responsible for the debromination.
Hydrogen Bond of 4-Amino-5H-[1]benzopyrano[3,4-c]pyridin-5-one Derivatives with Alcohols. I. Experimental Considerations
Authors: Fujimoto Akira , Inuzuka Kozo 
Published: July 2006

Abstract
The hydrogen bond between 4-amino-5H-[1]benzopyrano[3,4-c]-pyridin-5-one (benzopyranopyridine) derivatives including their related compounds (pyridine, aniline, and coumarin) and alcohols (methanol and ethanol) is discussed experimentally in detail. The formation of a hydrogen bond between the nitrogen atom of the benzopyranopyridine ring and the hydroxyl group of methanol was investigated by IR spectral measurements. The equilibrium constants for the formation of hydrogen-bonded 1 : 1 complexes were determined from the UV spectral data. The enthalpy changes accompanying complex formation were obtained from a knowledge of the temperature dependence of the equilibrium constants. The values of the enthalpy changes range approximately from 4.5 to 5.2 kcal/mol in the benzopyranopyridine–ethanol systems. It may be concluded that the hydrogen bond of the benzopyranopyridine–ethanol system occurs mainly at the nitrogen atom of benzopyranopyridine ring, because the thermodynamic properties for hydrogen bond formation between benzopyranopyridine and ethanol showed a striking resemblance to those of the pyridine–ethanol system. In addition, the presence of an intramolecular hydrogen bond between the amino and carbonyl groups of benzopyranopyridine derivatives was confirmed by means of IR spectra.
A Study of Surfactant Solutions Using the Liquid Membrane Electrode Selective to Alkyl Sulfate Ions
Authors: Yamauchi Akira , Kunisaki Takuma , Minematsu Toshiaki , Tomokiyo Yukiko , Yamaguchi Takeo , Kimizuka Hideo 
Published: July 2006

Abstract
Liquid membrane electrodes selective to alkyl sulfate ions were devised for octyl, decyl, and dodecyl sulfate ions, and employed in the study of micellar solutions. A nitrobenzene solution of hexadecyltrimethylammonium—alkyl sulfate complex was used as the liquid membrane. The membrane potential-logarithmic concentration showed a maximum at the critical micelle concentration (CMC), an increase with the Nernstian slope at the lower concentrations and a decrease at the higher concentrations. Below CMC, the presence of excess inorganic salt did not alter the Nernstian slope, i.e., the liquid membrane was more highly permselective to alkyl sulfate ions than to inorganic anions. From a simple thermodynamic consideration of a micellar solution based on the pseudo phase model of the micelle, the change in the activity of alkyl sulfate ions and the dissociation of the micelle were discussed. It has been deduced that the concentration of the singly dispersed surfactant ions above CMC is reduced with concentration, except for the presence of a large excess of added electrolyte, and that the degree of dissociation of the micelle is unaltered even when the excess electrolyte is added.
Thermodynamic Study on the Adsorption of 1-Octadecanol at Hexane/Water Interface
Authors: Matubayasi Norihiro , Motomura Kinsi , Aratono Makoto , Matuura Ryohei 
Published: July 2006

Abstract
The interfacial tension α between water and hexane solution of 1-octadecanol has been measured as functions of temperature T, pressure p, and mole fraction of 1-octadecanol in hexane x10 by the pendant drop method. The curves of γ vs. T, γ vs. p, and γ vs. x10 show noticeable break points. Calculated thermodynamic quantities such as energy changes, entropy changes, and volume changes associated with the adsorption show the points of discontinuity at a certain temperature, pressure, and composition, corresponding to the above breaking points. It has been clarified that the first order phase transition between the expanded and condensed states takes place at the interface like that of monomolecular films spread on water surfaces. The expanded state is characterized by a relatively high energy, high entropy, and large volume, while the condensed state by low energy, low entropy, and small volume.
Crystal Structures of N-(Benzyloxycarbonyl)prolylleucine Ethyl Ester and N-(t-Butoxycarbonyl)prolylleucine Benzyl Ester
Authors: Sugino Harumasa , Tanaka Isao , Ashida Tamaichi 
Published: July 2006

Abstract
The molecular structures of N-(benzyloxycarbonyl)prolylleucine ethyl ester and N-(t-butoxycarbonyl)prolylleucine benzyl ester, were determined by the X-ray method. The former belongs to the orthorhombic system P212121 with Z=4, a=9.917(3), b=21.960(3), and c=9.956(1) Å; the latter belongs to the monoclinic system P21 with Z=2, a=10.475(1), b=17.910(1), c=6.303(1) Å, and β=90.213(7)°. Both structures were determined by the direct method; the final R indexes are 0.062 for the former and 0.072 for the latter. An extended conformation found in both dipeptides shows that in terms of the Pro–Leu unit alone this conformation is preferable to the folded β-turn conformation such as is found in longer peptides. The leucyl side chain conformations found in peptides or amino acids were also studied. For the residues occurring in the peptides the C′–Cα–Cβ–Cγ–Cδ1 transzigzag conformation was found overwhelmingly, without any obvious relationships to the main chain torsion angles. On the other hand, for the C-termini leucyl residues and leucines the N–Cα–Cβ–Cγ–Cδ2 trans-zigzag conformation was rather preferred and the ψ values were restricted to a narrow range.
The Theoretical Study of External Magnetic Field Effect on Chemical Reactions in Solution
Authors: Hayashi Hisaharu , Nagakura Saburo 
Published: July 2006

Abstract
External magnetic field effects on chemical reactions in solution are studied theoretically and consequently reactions through radical pairs are shown to be controlled by a magnetic field. Some conditions necessary for the occurrence of the magnetic field effects are discussed, the effects being classified into three types: (1) the electronic Zeeman effect (ΔgβH), (2) the hyperfine interaction effect, and (3) the mixed effect.
Electronic Structures and Spectra of Aminoacetophenones and Related Compounds
Authors: Nakagaki Ryoichi , Nagakura Saburo , Kobayasm Takayoshi , Iwata Suehiro 
Published: July 2006

Abstract
The Sn←S0 and Sn←S1 transition bands were measured with m- and p-dimethylaminoacetophenones and related compounds in order to clarify the characters of the excited singlet states. The observed spectra were reasonably interpreted by the use of the theoretical results based on the composite molecule method. The longest wavelength band (S1←S0) of the meta isomer has mainly the local excitation (LE) character of aniline (1B2←1A1), while that of the para isomer is ragarded as the intramolecular charge-transfer band. In the para isomer the LE transition corresponding to 1B2←1A1 is covered by the intense CT band. The Sn←S1 transitions of the meta isomer are almost of LE character, whereas those of the para isomer are of back CT nature. This is mainly attributed to the difference in the character of S1.
Reduction of Calcium Interference on Barium Using the Nitrogen-Shielded Nitrous Oxide–Acetylene Flame in Atomic Absorption Spectroscopy
Authors: Kawamura Hisao 
Published: July 2006

Abstract
The interference effects of calcium on barium in atomic absorption spectroscopy, i.e., background absorption and noise effect having been attributed to the CaOH green band were further studied. The behavior of the interfering calcium hydroxide radical and the barium atom itself was studied in relation to the distribution of natural species, OH and CN, using conventional and nitrogen-shielded nitrous oxide–acetylene flames. A remarkable reduction in the calcium interference was demonstrated using a nitrogen-shielded version of moderately fuel-rich flames. This effect was attributed to the suppression of CaOH formation which was brought about by an improvement in the reducing nature of the flame with shielding.
The Synthesis of Hydrated Rare Earth Carbonate Single Crystals in Gels
Authors: Wakita Hisanobu 
Published: July 2006

Abstract
Hydrated rare earth carbonate single crystals were obtained in metasilicate gels. The formulas of the crystals were determined to be (RE)2(CO3)3·8H2O (RE=La, Pr) and (RE)2(CO3)3·4.54H2O (RE=Nd), and the crystal structures were determined to be of the lanthanit type.
The Complexing of the Ammonium Ion in Acetonitrile with Other Solvents. Investigation Using a Cation-sensitive Glass Electrode
Authors: Izutsu Kosuke , Nakamura Toshio , Murayama Taiji , Fujinaga Taitiro 
Published: July 2006

Abstract
As a part of potentiometric studies of the complexing of univalent cations in acetonitrile with other solvents by the use of a cation-sensitive glass electrode, investigations were carried out of the complexing of the ammonium ion in acetonitrile with such solvents as water, methanol, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone, and hexamethylphosphoric triamide, and also with dibenzo-18-crown-6. Prior to the study of the complexing, the cation-sensitive glass electrode was confirmed to respond in a Nernstian way to the change in the ammonium-ion activity which occurs due to the change of the solvent (solvent effect). The ammonium ion in acetonitrile formed complexes of mono- and di-solvated species with methanol and water. Formations of up to tri-solvated species were formed with DMF, DMA, and DMSO, and up to tetra-solvated species with 1-methyl-2-pyrrolidone and NMF. With HMPA, even penta-solvated species were formed. The complex formation constants of the mono-solvated ammonium ion, β1 (mol −1 dm3), were 1.7 with methanol, 5.6 with DMF, 14 with DMSO, 17 with DMA, 31 with 1-methyl-2-pyrrolidone, 3.0×102 with NMF, and 1.2×103 with HMPA. The association constant of ammonium perchlorate in acetonitrile was determined conductometrically to be 25 mol −1 dm3.
Mixed Ligand Complexes of Copper(II)-1-(2-Pyridylazo)-2-naphthol with Bidentate Ligands
Authors: Wada Hiroko , Ikuta Kazuyoshi , Nakagawa Genkichi 
Published: July 2006

Abstract
Formation constants of mixed ligand complexes of copper(II)-1-(2-pyridylazo)-2-naphthol chelate (Cu(pan)) with bidentate ligands, which accelerate the rate of color change of 1-(2-pyridylazo)-2-naphthol (PAN) indicator in copper(II)-EDTA titrations, were determined by the spectrophotometric method in 5 or 10% v/v dioxane–H2O at μ=0.1 (KNO3) and at 25 °C. The overall formation constants (logKCu(pan)Lpan.L=log ([Cu(pan)L]/[Cu][L][pan]) are 21.26 (5% dioxane) for 2,2′-bipyridine, 21.64 (10% dioxane) for ethylenediamine, 22.80 (5% dioxane) for 8-hydroxy-5-quinolinesulfonic acid, 19.39 (10% dioxane) for glycine, and 20.68 (10% dioxane) for iminodiacetic acid. These ligands coordinate with Cu(pan) chelate as bidentate ligands, and the mixed ligand complexes may have a distorted octahedron structure. Thus the Cu–pan bond in the mixed ligand complex is weakened.
Binuclear Metal Complexes, XXIII. Molecular Structure of a Heterometal Binuclear Complex, CuCo(fsaen)·3H2O(C18H18N2O9CoCu)
Authors: Mikuriya Masahiro , Okawa Hisashi , Kida Siego , Ueda Ikuhiko 
Published: July 2006

Abstract
The crystal structure of hetero-metal binuclear complex, CuCo(fsaen)·3H2O, with N,N′-bis(3-carboxysalicylidene)ethylenediamine (H4fsaen) was determined by the single-crystal X-ray diffraction method. The crystals are trigonal, space group P3221, a=b=12.845(2), c=9.962(1) Å, V=1423.5(4) Å3, and Z=3. The structure was solved by the heavy atom method and refined by the block-diagonal least-squares method to an R factor of 0.028. The copper atom is coordinated by two nitrogen atoms and two phenolic oxygen atoms in a square-planar manner. The cobalt atom is coordinated by two equatorial carboxyl oxygen atoms, two equatorial phenolic oxygen atoms and two axial water oxygen atoms in a distorted octahedral geometry. The detailed structure determined is in conformity with the magnetic and spectral properties previously reported.
Kinetic and Equilibrium Studies of the Complex Formation of Mercury(II) Acetate in Aqueous Solutions
Authors: Tamura Kiyoshi , Harada Shoji , Hiraissh Michinori , Yasunaga Tatsuya 
Published: July 2006

Abstract
An ultrasonic absorption study has been carried out on aqueous acidic solutions of mercury(II) acetate. The absorption data shows a single-relaxation phenomenon in the frequency range of 15–95 MHz. On the other hand, the results of the pH measurement indicate that the only mecury(II) acetate complexes conceivable in solution are of the HgL+ and HgL2 forms (L− denotes the acetate ion); the succesive formation constants of these complexes, together with the mercury(II) hydrolysis constants, are also determined. The equilibrium constants reported are: 2.1×103 for K1, 4.9×103 for K2, 6×10−4 for Kh1, and 1.0×10−3 for Kh2, at 30 °C and I=1. On the basis of the above results, the ultrasonic relaxation absorption is ascribed to the complex formation reaction: HgL++L−\leftrightharpoonsHgL2. The rate constants and the volume change of this reaction are determined to be: kfo=7.8×109 M−1 s−1, kbo=1.6×106 s−1, and ΔV=18 cm3 mol−1, at 30 °C.
Anodic Voltammetry and Its Analytical Application to the Detection and Simultaneous Determination of Hypoxanthine, Xanthine, and Uric Acid
Authors: Yao Toshio , Taniguchi Yoichi , Wasa Tamotsu , Musha Soichiro 
Published: July 2006

Abstract
The voltammetric oxidation of hypoxanthine, xanthine, and uric acid was investigated by means of linearsweep voltammetry, cyclic voltammetry, and controlled-potential coulometry. Hypoxanthine, xanthine, and uric acid each gave a single oxidation peak at a different potential, with a stationary glassy carbon electrode, over the wide pH range of 0–13. Hypoxanthine was initially oxidized in a two-electron step to xanthine, which was then further oxidized in a two-electron step to uric acid, as well as the enzymatic oxidation. All three substances were strongly adsorbed on the surface of the glassy carbon electrode, so that the concentration vs .anodic peak current curves were not linear. The adsorption on the electrode was very dependent on the pH, and especially at pH values around neutrality the anodic peaks were ill-defined. However, in such acid solutions as H3PO4 and H2SO4, the voltammetric oxidation was a diffusion-controlled process and the differences between the peak potentials were most pronounced (ca. 400 mV). Consequently, it was possible to determine simultaneously three hydroxypurine bases by using 1 M H2SO4 or 1 M H3PO4 as a supporting electrolyte, without prior treatment or separation procedures.
Preparation and Solid-phase Thermal cis-α↔cis-β Isomerization of the Chromium(III) Triethylenetetramine Complexes
Authors: Tsuchiya Ryokichi , Uehara Akira , Noji Kazuhiko , Yamamura Hitoshi 
Published: July 2006

Abstract
Heating of a mixture of CrCl3·6H2O and triethylenetetramine (trien) produced violet products which gave cis-α-[Cr2(OH)2trien2]X4·2H2O and cis-α-[Cr(OH)(H2O)trien]X2·H2O (X=Cl, Br or I) on treatment with aqueous NaX solutions. cis-α-[CrCl2trien]Cl·2H2O were obtained in the presence of a trace amount of water. Absolutely dry conditions are necessary for the preparation of cis-β-[CrCl2trien]Cl. The thermally induced reversible cis-α↔cis-β isomerization was detected in the complexes cis-α-[Cr(OH)(H2O)trien]Cl2·H2O and cis-β-[CrCl2-trien]Cl by means of derivatography and high-temperature IR spectroscopy. The former cis-α-hydroxoaqua complex was found to be converted irreversibly into cis-β-form above 225 °C in the solid-phase. The cis-β-form obtained readily isomerized to cis-α-form in aqueous media. The dimeric cis-α-[Cr2(OH)2trien2]4+ was converted gradually into the monomeric cis-α-[Cr(OH)(H2O)trien]2+ in water.