bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of Optically Pure (3S,5S)- and (3R,5R)-2,6-Dimethyl-3,5-heptanediol
Authors: Sugimura Takashi , Yoshikawa Masato , Yoneda Tohru , Tai Akira
Published: July 2006

Optically pure 2,6-dimethyl-3,5-heptanediol (1), a new chiral auxiliary, has been prepared by the enantiodifferentiating hydrogenation of 2,6-dimethyl-3,5-heptanedione over tartaric acid–NaBr–modified Raney nickel catalyst (TA–NaBr–MRNi), and the preferential recrystallization of the hydrogenation product. Absolute configuration of 1 was determined to be 3S, 5S by the chemical correlation with (−)-ethyl (S)-3-hydroxy-4-methylpentanoate.
Fluorescence Probes of Pyrene and Pyrene-3-carboxaldehyde for the Sol–Gel Process
Authors: Matsui Kazunori , Nakazawa Takumi
Published: July 2006

Silica sols and gels doped with pyrene (Py) and pyrene-3-carboxaldehyde (PyCHO) were prepared by the acidic hydrolysis of tetraethyl orthosilicate in ethanol. We studied the fluorescence of these molecules during the sol–gel–xerogel stages. The fluorescence intensity ratio of the vibronic bands of Py changed remarkably, while the fluorescence maximum of PyCHO showed a significant red shift as the gel dried. Such a spectral change was ascribed to an increase in the environmental polarity of the probe molecules upon the evaporation of the ethanol. The estimated dielectric constant of the gel after drying in a vacuum is about 72, just slightly less polar than water (80). The silica cage produced by the sol–gel process is probably rich in silanols, resulting in a relatively polar environment.
Promoter Effect of Alkali Metal Oxides and Alkali Earth Metal Oxides on Active Carbon-Supported Ruthenium Catalyst for Ammonia Synthesis
Authors: Aika Ken-ichi , Kawahara Toshikazu , Murata Shuzo , Onishi Takaharu
Published: July 2006

Promoter effects of alkali metal nitrates and alkali earth metal nitrates on Ru/A.C. (active carbon) were studied in order to prepare an effective catalyst for ammonia synthesis. Of alkali metal nitrates, RbNO3 was more effective than CsNO3 and KNO3. Alkali earth metal (Mg, Ca, Sr, Ba) nitrates were also found to be effective promoters on Ru/A.C. catalysts. Of them heavier alkali earth metal elements were more effective (Ba>Sr>Ca>Mg). Ba(NO3)2 was as effective as CSNO3, which was not expected from the stand point of electronegativity. The transformation of promoter precursors to active compounds (nitrates to oxides or hydroxides) and the interaction of promoters and ruthenium were discussed. Precursor of ruthenium salt was also studied. RuCl3·3H2O and [Ru(NH3)6]Cl3 gave higher activities than Ru3(CO)12. It was discussed that RuCl3 gave finer Ru particles than Ru3(CO)12 on active carbon. The turn over frequency (TOF) of Ru–Rb+/A.C. was lower than those of RU–Cs+/Al2O3 and of Ru–Cs+/MgO.
The Hydrolytic Property of Imidodiphosphate in Solid and in an Aqueous Medium
Authors: Watanabe Makoto , Sato Shoji , Wakasugi Khosaku
Published: July 2006

Crystalline tetrasodium imidodiphosphate decahydrate, Na4P2O6NH·10H2O, was directly converted to diphosphate by heating above 200°C in air according to the equation:

Na_2O_3PNHPO_3Na_2+H_2O→Na_2O_3POPO_3Na_2+H_3

Amorphous tetrasodium imidodiphosphate was prepared by stirring the crystalline imidodiphosphate in excess ethanol. The substitution of an imino group of the amorphous imidodiphosphate for bridging oxygen took place much faster than that of the crystalline one. Imidodiphosphate was hydrolyzed to phosphoramidate and orthophosphate in an aqueous solution:

Na_2O_3PNHPO_3Na_2+H_2O→Na_2PO_3NH_2+Na_2HPO_4
X-Ray Structure Determination of Stereoisomers with Respect to Cyclobutene Ring of 10,10-Ethylenedioxy-1-methoxycarbonyl-2-methyl-7-oxatricyclo[6.4.0.02,5]dodec-3-en-6-one
Authors: Matsui Takanao , Hashimoto Takashi , Tada Toshiji , Nozaki Hiroshi , Nakayama Mitsuru
Published: July 2006

The structures of the title compounds were determined by X-ray crystallographic analysis. The results lead to a revision of the previously proposed structure for photochemical cycloadduct of 9,9-ethylenedioxy-6-methoxycarbonyl-5-methyl-2-oxabicyclo[4.4.0]dec-4-en-3-one with acetylene.
Formation Mechanism of the Complexes between DMSO and Halogen Atoms. I. Pulse Radiolysis Studies
Authors: Sumiyoshi Takashi , Katayama Meiseki
Published: July 2006

The formation mechanism of DMSO–halogen atom complexes in the solution of DMSO and halocarbons has been investigated by pulse radiolysis method. Three formation processes have been found depending on the the solution component. In the case of DMSO/CCl4 mixtures, the absorption band at 400 nm due to the complexes has been observed at any composition. In CCl4 solutions, the complex is formed by the reaction of the chlorine atom with DMSO, while in DMSO solutions, the reaction between the parent radical cations of DMSO and Cl− is dominant. It is suggested that the contribution of direct excitation of the strongly interacted ground state DMSO–CCl4 encounter pairs becomes more important with increasing CCl4 concentration.
Tris(6,6′-diamino-2,2′-bipyridine)ruthenium(II): Effect of High Interligand Steric Strain on the Structure
Authors: Araki Koji , Fuse Masahiro , Kishii Noriyuki , Shiraishi Shinsaku , Kodama Teruyuki , Uchida Yasuzo
Published: July 2006

A series of the ruthenium(II) complexes 1–4, [Ru(dabp)3−n(bpy)n](BF4)2 (n=0, 1, 2, and 3, respectively, dabp=6,6′-diamino-2,2′-bipyridine, and bpy=2,2′-bipyridine), having a different degree of interligand steric strain were synthesized, and the effect of the interligand steric strain caused by the amino substituents on their structures was examined. A crystallographic study showed that the two pyridine rings of dabp in the complex 1 were in a slightly twisted configuration in order to relieve the interligand strain. Similar twisted configurations were suggested for the bipyridine moieties of dabp and bpy in the complexes 1–3 in dimethyl sulfoxide solution.
An Efficient Method for the Direct Peroxygenation of Various Olefinic Compounds with Molecular Oxygen and Triethylsilane Catalyzed by a Cobalt(II) Complex
Authors: Isayama Shigeru
Published: July 2006

An efficient method for the direct peroxygenation of various olefinic compounds with molecular oxygen and triethylsilane (Et3SiH) was developed by the use of a catalytic amount of a bis(1,3-diketonato)cobalt(II) complex. According to the above method, 1-phenyl-3-triethylsilydioxybutane (2) was directly produced from 4-phenyl-1-butene (1) by means of a reaction with O2 and Et3SiH at room temperature. Styrene (3) and ethyl acrylate (5a) were also smoothly peroxygenated to give 1-phenyl-1-triethylsilyldioxyethane (4) and ethyl 2-triethylsilyldioxypropionate (6a) by using a small amount of t-BuOOH as an initiator. The successive desilylation of 6a and reduction of the resulting ethyl 2-hydroperoxypropionate (8a) afforded the corresponding alcohol, ethyl lactate (10a), in a high yield. The synthetic utility of the present peroxygenation reaction was demonstrated in the preparation of α-hydroxy esters 10a–e from several α,β-unsaturated esters 5a–e via the corresponding triethylsilyldioxy derivatives.
The Stereochemistry and Reactivity of Metal-Schiff Base Complexes. VII. Contribution of Hydrophobic Interligand Interaction to Chiral Recognition of Phenylalaninate and Tryptophanate with (1R,2R)-N,N′-Disalicylidene-1,2-cyclohexanediaminecobalt(III) Complex
Authors: Fujii Yuki , Yoshikawa Yuzo , Syoji Masato , Shinohara Homare
Published: July 2006

The stability constants, K1, of Δ-β2-diastereomers of mixed ligand cobalt(III) complexes with a chiral quadridentate Schiff base (sal-(R,R)-chxn), derived from salicylaldehyde and (R,R)-1,2-cyclohexanediamine, and d- or l-amino acidate (aa−=gly, ala, val, leu, thr, phe, trp, pro, asp, asn, and glu) were determined spectrophotometrically in water–methanol (2:3 by volume) containing acetate buffer (0.3 mol dm−3) at 22°C: trans-[Co{sal-(R,R)-chxn}(H2O)2]++aa−\oversetK1\ightleftharpoonsΔ-β2-[Co{sal-(R,R)-chxn}(aa)]. The K1 values range from 5.6×106 to 1.2×109 mol−1 dm3 and obey a linear free energy relationship except for d-phe, d-trp, d-asp, d-asn, and d-pro. In the cases of d-phe, d-trp, d-asp, and d-asn, their stability constants are 5–30 times as high as those for the corresponding l-aa. Extraordinary stabilization of the d-phe and d-trp complexes is discussed in terms of the interligand stacking of the aromatic rings between the Schiff base ligand and a side chain of amino acidate on the basis of conformational analysis and 1H NMR spectra.
Physical Properties of 3-Propylsydnone
Authors: Sasaki Yukio , Ishibashi Yoshimoto
Published: July 2006

The physical properties of 3-propylsydnone at various temperatures were investigated by dielectric constant, refractive index, density and viscosity measurements. The dielectric constant (ε) of 3-propylsydnone is very high compared to those of many organic solvents. For example, this value was found to be 95.0 at 25 °C. The dielectric constant of 3-propylsydnone is approximately expressed by a cubic equation of the temperature. The Kirkwood equation holds over the range from 10 to 150 °C. The refractive index (nD) and density (ρ) data for 3-propylsydnone are described as linear equations of the temperature with maximum deviations of 0.008 and 0.005%, respectively. The viscosity (η) of 3-propylsydnone at 25 °C is 8.45 cP (1 cP=10−3 N s m−2). This value is larger than those of many organic solvents, but smaller than those of sulfolane and 1,2-ethanediol. A plot of logη vs. 1/T for 3-propylsydnone yields a straight line. The activation energy of the viscosity for 3-propylsydnone was found to be 25.0 kJ mol−1.
The Electroxidation of Methanol in the Potential Region of Platinum–Oxygen Layer
Authors: Matsui Hiroshi , Kunugi Akira
Published: July 2006

Methanol oxidation at a platinum electrode in 0.5 mol dm−3 sulfuric acid at high potentials was retarded by the formation of both an oxygen layer and a new type of retarding substance from methanol. The presence of the retarding substance was confirmed by the oxygen-deposition method. During retardation due to the formation of an oxygen layer, the rate of methanol oxidation both decreased and increased with increasing oxygen coverage and potential, respectively. The reverse efcets of oxygen coverage and potential concurrently occurred when the potential was a variable. At low oxygen coverage, the decreased effect of oxygen coverage was more remarkable than the increased effect of the potential, while the order of the remarkableness was reversed at middle coverage. The reversal of the order could be explained in terms of a catalytic reduction of the oxygen layer with methanol.
Covalent Immobilization of Ultrafine Platinum Particles onto Crosslinked Polymer Support and Their Application to Catalysis
Authors: Ohtaki Michitaka , Toshima Naoki , Komiyama Makoto , Hirai Hidefumi
Published: July 2006

Ultrafine particles of platinum were prepared as stable aqueous dispersions by a photoreduction method in the presence of soluble protective polymers. By use of the protective polymer with methyl acrylate residues as a reactive group, the polymer-protected ultrafine platinum particles were successfully immobilized onto crosslinked polymer supports with amino groups. The present immobilization was attributed to the formation of amide bonds by the reaction of methyl acrylate residues in the protective polymer with amino groups in the support, and the immobilization mechanism was investigated by the model reaction using protective polymer with p-nitrophenyl acrylate residues as a reactive group. The immobilized platinum particles obtained show high catalytic activity for hydrogenation of olefins and specific substrate selectivity due to a hydrophilic–hydrophobic interaction between the support and the substrate.
Apparent Molar Volume and Viscosity of N-Methylpyridinium Iodide and Its Methyl-Substituted Derivatives in Water
Authors: Swain R K , Tiwary L K , Behera B
Published: July 2006

The apparent molar volume and the viscosities of N-methylpyridinium iodide and its methyl derivatives in water at 25, 30, 35, and 40 °C are reported. The apparent molar volumes obey Masson’s equation. The φv° and Sv* values indicate strong ion–ion interaction in water. φv° is linearly related to temperature. The relative viscosity data of these salts obey Jones–Dole and Vand equations well. The A and B values of Jones–Dole equation and Q values of Vand equation suggest greater solvation in case of NMPI and the β-CH3 salt and greater ion–ion interaction in case of α-CH3 and γ-CH3 salts. The data have been discussed in terms of hydrophobic hydration and solvent shared ion pairs. The free energy of activation for viscous flow are almost equal for these salts. The importance of A, B, B+, and Q to the study of the solvent structure is discussed.
Coordination Chemistry of Proton. In Situ Synthesis and X-Ray Structural Analysis of 2-Hydroxyethanaminium Picrate, HOCH2CH2NH3+·C6H2N3O7−
Authors: Poonia Narinder S , Chandra Ramesh , Sheldrick W S
Published: July 2006

2-Hydroxyethanaminium picrate, HOCH2CH2NH3+·C6H2N3O7−, is prepared through a metathetical reaction of Mg(Pic)2 and HOCH2CH2NH2 (2-aminoethanol, MEA) in ethanol through in situ generation of HPic. Orange yellow crystals (MEAH+Pic−) (mp 163°C) of the “Salt” are produced alongwith the colorless Mg(CH2NH2CH2O−)2, even when MEA is less than 1:1 with respect to Mg(Pic)2. The crystals are monoclinic, space group P21/c, a=11.797(4), b=14.288(3), c=7.124(2) Å, β=97.63(2)°, Z=4, Dcal=1.62 g cm−3. Structural analysis from the 1617 reflection data (R=0.059, Rw=0.056) reveals that the picric acid proton is formally transferred to the MEA nitrogen (N–H, 0.968 Å) and is merely bonded to the phenoxide of Pic (H···O−, 1.951 Å) and weakly also to an oxygen of o-nitro group of the anion (H···ONO, 2.379 Å). The transferred proton becomes an integral part of the cation MEAH+ and completes the fourth covalent bond of the sp3 N of MEA, and does not show any special affinity for the anionic oxygen of Pic; the N–H···O− (142.8°) and N–H···ONO (141.6°) angles are closely comparable.
Creatones A and B. Revision of the Structure for the Product of Oxidation of Creatinine and Creatine
Authors: Nakamura Ko , Ohira Chikara , Yamamoto Hiroshi , Pfleiderer Wolfgang , Ienaga Kazuharu
Published: July 2006

The structure for a product of the oxidation of creatinine is revised to be N-(N′-methylamidino)oxamic acid (4). Acyclic product 4 and its cyclic product, 2-amino-1-methyl-4,5-imidazoledione, are coined as creatones B and A, respectively. The first synthesis of 2-methylamino-4,5-imidazoledione is also described.
Reaction of 2-Chlorocyclohepta[b]pyrrole-3-carbaldehyde with o-Phenylenediamine
Authors: Abe Noritaka , Emoto Yoshifumi
Published: July 2006

Reaction of 2-chlorocyclohepta[b]pyrrole-3-carbaldehyde with o-phenylenediamine gave 1H-2-(2-chlorocyclohepta[b]pyrrol-3-yl) benzimidazole (3a) and 5H-12,13-dihydrocyclohepta[1′,2′:4,5]pyrrolo[2,3-b][1,5]benzodiazepine (4a). Some reactions of 3a and 4a were also described.
Formation Mechanism of the Complexes between DMSO and Halogen Atoms. II. Laser Flash Photolysis Studies
Authors: Sumiyoshi Takashi , Watanabe Kazuyuki , Syogen Satoshi , Kawasaki Masahiro , Katayama Meiseki
Published: July 2006

The laser flash photolysis of DMSO/CCl4 mixed solutions produces the transient DMSO–Cl complex with an absorption maximum at 400 nm. The formation of the complex has been explained by the direct photoexcitation of the ground state associated DMSO/CCl4 pair on the basis of the spectroscopic data and the known macroscopic physical properties of binary solutions of DMSO and CCl4.
Synthesis and Square Planar-Octahedral Equilibrium of Bismacrocyclic Dinickel(II) Complexes with Polymethylene Bridges of Various Lengths
Authors: Mochizuki Katsura , Ikeda Yosihito
Published: July 2006

A new series of binuclear nickel(II) complexes with bis(tetraazamacrocycle), 7,7′-polymethylenebis[3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene]dinickel(II) perchlorates with polymethylene bridges with a length of 2–6-C, was synthesized, as well as the corresponding free ligands. The dinickel(II) complexes were found to be in equilibrium between square planar and octahedral forms in water. The equilibrium shifts toward the octahedral side as the polymethylene bridge becomes short.
Oxidation of Coals in Liquid Phases. X. Mechanism of the Cleavage of Benzenecarboxylic Acids to Oxalic Acid and Carbon Dioxide by the Base-Catalyzed Oxygen-Oxidation
Authors: Ichinose Shuji , Okuwaki Akitsugu
Published: July 2006

A kinetic study of the oxidation of benzenecarboxylic acids has been performed in order to clarify the mechanism. The reaction products were oxalic acid and carbon dioxide, along with a trace of acetic acid. The oxidation rate of phthalic acid was proportional to the first order of the molality of phthalic acid, the molality of NaOH, and partial oxygen pressure, respectively; the apparent activation energy was 126 kJ mol−1. These results show that the rate-determining step is a cleavage of the benzene ring proceeded by a base-catalyzed oxygen-oxidation mechanism in which a carbanion formed by hydrogen extraction from an aromatic ring is attacked by oxygen. In the cleavage of phthalic acid, NaOH increases the selectivity to form oxalic acid as well as the oxidation rate. In the oxidation of 1,2,3-benzenetricarboxylic acid the same mechanism was recognized, but not for benzenehexacarboxylic acid which has no hydrogen on the benzene ring.
Synthesis and Characterization of 18-Molybdopyrophosphate Complex
Authors: Himeno Sadayuki , Saito Atsuyoshi , Hori Toshitaka
Published: July 2006

The existence of a heteropoly 18-molybdopyrophosphate was ascertained in both solid and solution states. The yellow complex was formed in solutions of 0.05 M (M=mol dm−3) Mo(VI)/5×10−3 M pyrophosphate/0.1–0.7 M HCl/60% (v/v) CH3CN at ambient temperatures, being isolated as tetraalkylammonium (R4N+) salts where R=n-C4H9 and C2H5. The presence of organic solvents was essential for the preparation of the complex. The 18-molybdopyrophosphate complex underwent a four-step reduction in 95% (v/v) CH3CN–water containing 0.1 M HClO4, yielding mixed-valence blue species by the electrochemical reduction at the respective steps of a reversible two-electron transfer. The heteropoly skeleton is retained in the blue complexes. The UV-visible and IR spectroscopic characteristics, and the formation conditions of the 18-molybdopyrophosphate complex were also elucidated.
Adsorption of Cholesterol at Hexane/Water Interface
Authors: Matsuguchi Masanobu , Aratono Makoto , Motomura Kinsi
Published: July 2006

The interfacial tension between hexane solution of cholesterol and water was measured as a function of temperature and the mole fraction of cholesterol in hexane under atmospheric pressure. The interfacial tension vs. mole fraction of cholesterol curve was observed to have two break points at a certain temperature; the concentration of the break point increases with increasing temperature. The experimental results were analyzed by applying the rigorous thermodynamics of adsorption at interfaces developed previously. The excess number of moles of cholesterol and the thermodynamic quantity changes associated with its adsorption were found to show the discontinuous changes at the break points. It was concluded that the first-order phase transition takes place from the gaseous to the expanded state and from the expanded to the condensed one in the adsorbed film of cholesterol at the hexane/water interface.
Total Synthesis of (−)-Chiloscyphone, Sesquiterpenoid Isolated from the Liverwort. Absolute Configuration of (−)-Chiloscyphone and (+)-Chiloscypholone
Authors: Tori Motoo , Hasebe Takeshi , Asakawa Yoshinori
Published: July 2006

The absolute configurations of (−)-chiloscyphone and (+)-chiloscypholone isolated from the liverwort Chiloscyphus polyanthos and C. pallescens respectively, have been determined by the total synthesis of the optically active compound. The 1,4-addition of vinylmagnesium bromide to 3,4-dimethyl-2-cyclohexenone in the presence of copper(I) bromide-dimethyl sulfide complex and the subsequent aldol condensation of the ketoaldehyde derived in several steps afforded the hydrindenone derivative. The key intermediate alcohol has been resolved by the use of (1S)-(−)-camphanic chloride. The optically active hydroxy ester has been converted to (−)-chiloscyphone.
Electrochemical Polymerization of N-Trimethylsilylpyrrole and Other Substituted Pyrroles Which Contain Si or Ge Atom(s) in Their Monomer Structures
Authors: Okano Mitsutoshi , Toda Atsuko , Mochida Kunio
Published: July 2006

N-Trimethylsilylpyrrole and three new compounds; N-trimethylgermylpyrrole, N-chloromethyldimethylsilylpyrrole, and N-pentamethyldisilanylpyrrole, were synthesized. These four monomers were electrochemically polymerized and four new organic conducting polymers were obtained. Resulting polymers had good film producibility and conductivity as high as that for polypyrrole. They showed three distinguishable colors at different potentials: blue in the doped state, yellow in the undoped state, and reddish color in between.
Stereochemistry of NAD(P)-Coenzyme in the Reaction Catalyzed by Glycerol Dehydrogenase
Authors: Nakamura Kaoru , Shiraga Tsuyoshi , Miyai Takehiko , Ohno Atsuyoshi
Published: July 2006

The coenzyme stereospecificities in the reaction of glycerol dehydrogenases (GDH) from various microbial sources have been determined. It is found that the nicotinamide-coenzymes (NADH and NADPH) employed by GDHs from eucaryotes exert the pro-S specificity, whereas those employed by procaryotes exert the pro-R specificity. The stereospecificity of the coenzyme seems to have a correlation with chemical evolution of GDH as well as biological evolution of the host organism.
A Grignard-Type Addition of Allyl Unit to Aldehydes by Using Bismuth and Bismuth Salt
Authors: Wada Makoto , Ohki Hidenori , Akiba Kin-ya
Published: July 2006

In the presence of metallic bismuth, bismuth(III) chloride–metallic zinc, or bismuth(III) chloride–metallic iron, allylic halides have been found to react with aldehydes under mild conditions to give the corresponding homoallylic alcohols in high yields with high chemo-, regio-, and stereoselectivity. Allylic halides have been also found to react with aldehydes at room temperature in tetrahydrofuran–water by using bismuth(III) chloride–metallic aluminium to afford the expected homoallylic alcohols in high yields.
Kinetic Study on the Alkaline Hydrolysis of S,S-Diaryl-N-halosulfilimines
Authors: Yoshimura Toshiaki , Tsukurimichi Eiichi , Kita Hiroshi , Fujii Hiroshi , Shimasaki Choichiro
Published: July 2006

Kinetics for the alkaline hydrolysis of S,S-diaryl-N-bromosulfilimines were carried out in aqueous methanol. The observed pseudo-first-order rate constants were found to give a linear correlation with the concentration of sodium hydroxide, k=k1+k2[NaOH]. The first-order rate constants k1 showed a large negative Hammett ρ value (−2.43) for the substituent effect on the phenyl group, nearly zero activation entropy (−0.9±13.1 JK−1mol−1) and a relatively large m value (0.638) against the solvent ionizing power Y value suggesting that the reaction process for k1 close to SNl. The salt effect, the deuterium solvent isotope effect and the steric effect are also in accord with the SNl mechanism. On the other hand, the second-order rate constants k2 revealed a small Hammett ρ value, a negative activation entropy (−44.0±4.0 JK−1mol−1), a small m value (0.153) and a steric deceleration by ortho substituents showing that the reaction for k2 is SN2-like. The salt effect and the solvent isotope effect are also compatible with the SN2-like mechanism. Meanwhile, the k1 for S,S-diphenyl-N-halosulfilimines remarkably increased in the order of N-iodo<N-bromo<N-chloro. This reactivity might be due to the lone pair-lone pair repulsion at the reactant state. From these observations, the alkaline hydrolysis of S,S-diaryl-N-halosulfilimines was confirmed to proceed via concurrent two mechanisms, the SN2′-like mechanism involving nitridosulfonium cation (>+S≡N) as an intermediate and the SN2′-like mechanism with the transition state in which the N-X bond cleavage is more progressed than the S–O bond formation with nucleophiles (−OH, −OMe).
DABCO-Mediated Synthesis and Biological Activity of Cyanohydrin Esters
Authors: Hoffmann H M R , Ismail Z M , Hollweg Reiner , Zein Abdul R
Published: July 2006

Cyanohydrin esters 1–31 have been prepared from α-ketonitriles and aldehydes using DABCO (1,4-diazabicyclo[2.2.2] octane) as nucleophilic acylation catalyst. The modified piperonal 8 was found to inhibit the formation of thromboxane synthetase.
The Dissociation Equilibrium of the Copper(II) Acetate Dimer in Acetic Acid
Authors: Kikuchi Yoichi , Suzuki Toshio , Sawada Kiyoshi
Published: July 2006

The dissociation equilibrium of the copper(II) acetate dimer in acetic acid was studied by means of high-sensitivity spectorophotometry. The dissociation constant of the nonaquated dimer was determined to be Kdis=10−6.2±0.2 at 25 °C. The dissociation was promoted in the presence of water. The formation constant of the monoaquated monomer was estimated to be Kml=3.0.
Synthetic Study on Peptide Antibiotic Nisin. III. Synthesis of Ring C
Authors: Fukase Koichi , Kitazawa Manabu , Wakamiya Tateaki , Shiba Tetsuo
Published: July 2006

A cyclic sulfide moiety corresponding to ring C in peptide antibiotic nisin was successfully synthesized from a disulfide compound prepared from a heptapeptide involving l-cysteine and threo-3-methyl-d-cysteine through desulfurization reaction with hexaethylphosphorus triamide.
Structure for the “Biguaiazulene-3,3′-dione” and Efficient Preparation of 5-Isopropyl-3,8-dimethyl-1,7-azulenedione
Authors: Matsubara Yoshiharu , Morita Masanori , Matsui Shuichi , Takekuma Shin-ichi , Yamamoto Hiroshi , Ito Shunji , Morita Noboru , Asao Toyonobu , Nozoe Tetsuo
Published: July 2006

The dimeric compound formed from 3-guaiazulenol has been found to be identical with the main product (Q2) of the peracid oxidation of guaiazulene, thus the previous structure of Q2 being revised to be a ca. 1:1 mixture of meso (5R,5′S) and two enantiomeric (5R,5′R and 5S,5′S) forms of [5,5′-biguaiazulene]-3,3′(5H,5′H)-dione. Autoxidation of Q2 in pyridine at 25 °C for 1 d mainly gives the title 1,7-azulenedione.
Reactions of Cinnamylideneamino Isoxazoles with Dimethyl Acetylenedicarboxylate
Authors: Thirmal Rao Errabelli , Rajanarendar Eligeti , Krishnamurthy Ananthula
Published: July 2006

The interaction of 4-cinnamylideneamino-3-methyl-5-styrylisoxazoles (1) with dimethyl acetylenedicarboxylate has given an isoxazolyldihydropyridine (2) as major and an isoxazolylaminofumarate (3) as minor products respectively. 3-Cinnamylideneamino-5-methylisoxazoles (4) behave similarly. Isoxazolylaminofumarates (3 and 6) have been identified by unambiguous synthesis.
Studies on 5-8 Fused Ring Compounds. V. The Conformations of Eight-Membered Rings in 5-8-5 Fused Ring Compounds and Their cis-trans Isomerization
Authors: Umehara Misao , Hishida Shinzabro , Okuda Masami , Ohba Shigeru , Ito Masatoki , Saito Yoshihiko , Zen Shonosuke
Published: July 2006

The 5-8-5 fused ring compounds, synthesized by photocycloaddition, cis-cisoid-cis- and cis-transoid-cis-tricyclo[9.3.0.04,8]tetradecane-2,9-dione (1-A and 2-A) and cis-cisoid-cis-tricyclo[9.3.0.03,7]tetradecane-2,9-dione (3-A) were isomerized to trans isomers (1-B, 1-C, 2-B, 2-C, and 3-B) at ring junction under basic conditions. Their molecular structures except for 1-B were determined by X-ray crystallography. The eight-membered rings of these 5-8-5 fused ring compounds were found in various conformations, boat-chair, twist-boat (S4), chair, twist-boat-chair, and chair-chair forms. With regard to the conformations of their eight-membered rings the strain energies were calculated by MM2 and the predicted conformations were compared with those obtained by X-ray crystallography.
Effect of Supporting Carbon Particles on Electric and Electrochemical Properties of Polarizable Electrodes Using Activated Carbon Fiber Sheets in Electric Double Layer Capacitors
Authors: Tanahashi Ichiro , Yoshida Akihiko , Nishino Atsushi
Published: July 2006

The effect of supporting carbon particles on the electric and electrochemical properties of polarizable electrodes in electric double layer capacitors have been studied. The polarizable electrodes examined were activated carbon fiber sheets (ACF sheets) composed of phenolic resin-based activated carbon fibers, carbon fibers, and pulps. The sheets with supporting carbon particles have been prepared by impregnation of the sheets with suspension of submicron carbons. The electric resistance of the sheets with supporting carbon particles of 18.7 g m−2 decreased by 53% and the differential electric double layer capacitance in an organic electrolyte increased by 12%. In accordance with these results, the impedance of the capacitors composed of ACF sheets with supporting carbon particles decreased by 33% and the capacitance increased by 11% in comparison with those of the capacitors composed of the sheets without supporting ones.
Optical Resolution of Arsine Oxides by Complexation with Optically Active [1,1′-Binaphthyl]-2,2′-diol
Authors: Mori Koji , Toda Fumio
Published: July 2006

Some dialkylarylarsine oxides were resolved efficiently by complexation with optically active [1,1′-binaphthyl]-2,2′-diol.
Dynamical Structures of Normal Alkanes, Alcohols, and Fatty Acids in the Liquid State as Determined by Viscosity, Self-Diffusion Coefficient, Infrared Spectra, and 13CNMR Spin-Lattice Relaxation Time Measurements
Authors: Iwahashi Makio , Yamaguchi Yoshimi , Ogura Yoshio , Suzuki Masao
Published: July 2006

The dynamical structures of molecules of normal alkanes (C5–C14) and normal fatty acids (C8 and C9) in the liquid state were estimated through analyses of their self-diffusion coefficients (D), viscosities (η), molar volumes, and 13CNMR spin-lattice relaxation time (T1). The apparent hydrodynamic radius evaluated from D and η for the alkanes was ca. 2.5×10−10 m and that for the fatty acids, ca. 3.1×10−10 m, irrespective of their hydrocarbon chain length: The former value is almost equal to that of the van der Waals radius (2.4×10−10 m) of the cross section of a hydrocarbon chain; the latter is in agreement with that of the normal alcohols reported in a previous paper. It is thus concluded that in the pure liquid of a rod-like compound such as normal alkane, alcohol, and fatty acid, the free rotational (end-over-end) as well as the transverse motion of the rod-like molecule is severely restricted due to the entanglements of the molecules; only a longitudinal translation is allowed. In addition, the infrared-spectrum results suggest that a unit in translational motion for a normal fatty acid is a dimer.
The Amino-Imino Tautomerization of 2,6-Diaminopyridine by Interaction with Ethanol
Authors: Inuzuka Kozo , Fujimoto Akira
Published: July 2006

The UV absorption spectrum of 2,6-diaminopyridine was measured in an ethanol-and-isooctane mixed solvent while increasing the concentration of ethanol at room temperature and changing the temperature from 20 to −100°C at a constant concentration of ethanol. Its spectrum showed a clear shoulder band near 345 nm as the concentration of ethanol increased to over 5×10−1 mol dm−3 at room temperature and as the temperature decreased from 20 to −100°C in 1×101 mol dm−3 of ethanol in the isooctane solution. The corresponding band near 345 nm was observed for 2-amino-6-methylaminopyridine and 2,6-bis(methylamino)pyridine; however, it was not found for 2-amino-6-dimethylaminopyridine, 2-methylamino-6-dimethylaminopyridine, or 2,6-bis(dimethylamino)pyridine in the same experiments. The shoulder band near 345 nm was, on the basis of the spectroscopic results and the molecular orbital method, assigned to the π–π* absorption band of the (E)-6-amino-2(1H)-pyridinimine formed through the hydrogen-bond formation of 2,6-diaminopyridine with two ethanols. The formation of the imino form with two ethanols may be restricted to the 2,6-diaminopyridine and its methyl derivatives, in which each amino group at the 2- and 6-positions has at least one hydrogen atom. The proton transfer from ethanol to 2,6-diaminopyridine in the 2,6-diaminopyridine-ethanol complex may be energetically difficult in the ground state.
Syntheses of 22,23-Dihydro-1α,25-dihydroxyvitamin D2 and Its 24R-Epimer, New Vitamin D2 Derivatives
Authors: Tsuji Masahiro , Yokoyama Shinji , Tachibana Yoji , Ikekawa Nobuo
Published: July 2006

New 1α,25-dihydroxy vitamin D2 derivatives (22,23-dihydro-1α,25-dihydroxyvitamin D2 (2a)) and its 24R-epimer (2b), were synthesized by two procedures. 22-Oxo-5α,8α-(4-phenyl-3,5-dioxo-1,2,4-triazolidine-1,2-diyl)-23,24-dinor-6-cholene-1α,3β-diyl diacetate (8), obtainable readily from ergosterol, was converted to 22-phenylsulfonyl-5α,8α-(4-phenyl-3,5-dioxo-1,2,4-triazolidine-1,2-diyl)-1α,3β-bis(tetrahydropyranyloxy)-23,24-dinor-6-cholene (14) or 22-iodo-5α,8α-(4-phenyl-3,5-dioxo-1,2,4-triazolidine-1,2-diyl)-1α,3β-bis(tetrahydropyranyloxy)-23,24-dinor-6-cholene (16). Condensation of the C-22 sulfone (14) with (3R)-4-iodo-2,3-dimethyl-2-butanol THP ether, or the C-22 iodide (16) with (3R)-2,3-dimethyl-4-phenylsulfonyl-2-butanol THP ether followed by desulfonylation and successive deprotection gave 5,7-ergostadiene-1α,3β,25-triol (21a), which led to 2a upon irradiation and subsequent thermal isomerization. Similarly, a 24R-epimer of 2a was synthesized.
An Ab Initio Molecular Orbital Study on the Ene Reaction of Methyl Acrylate with Propene
Authors: Uchimaru Tadafumi , Tsuzuki Seiji , Tanabe Kazutoshi , Hayashi Yujiro
Published: July 2006

The exo and endo transition structures for the ene reaction of methyl acrylate with propene have been located with RHF calculations at the 3-21G and 6-31G levels. Energetics have been evaluated with the 6-31G* basis set and MP2 correlation energy correction. The transition-state geometries and the calculated energetics have been compared with those for the parent ene reaction between ethylene and propene. The exo and endo transition structures resemble rather closely that for the parent ene reaction. Reasonable substituent effects are indicated on activation energies and extents of electron transfer in the transition states. According to the calculated overlap populations, the transition structures for methyl acrylate ene reaction have less asynchronous character in the bond reorganization as compared with the parent ene reaction. The relatively small stability difference between exo and endo transition structures suggests that intrinsic exo/endo selectivity in the ene reactions is not so obvious as in the Diels–Alder reactions.
The Lactam–Lactim Tautomerization of Monoamino-Substituted 2-Pyridinols in Tetrahydrofuran
Authors: Fujimoto Akira , Inuzuka Kozo
Published: July 2006

MINDO/3 calculations have been performed on 3-amino-, 4-amino-, 5-amino-, and 6-amino-2-pyridinols to estimate their molecular geometries. The lactam-lactim tautomerization from amino-2-pyridone to amino-2-pyridinol was expected for 5-amino- and 6-amino-2-pyridinols from the MINDO/3 calculations. In addition, their dimer formation energies were evaluated by the CNDO/2 method. Among the four amino-2-pyridones, 6-amino-2-pyridone has the largest dimer formation energy and 3-amino-2-pyridone the smallest. Furthermore, to certify the tautomerization of 3-amino-, 5-amino-, and 6-amino-2-pyridinols the UV absorption and fluorescence spectra were measured, and compared with those of their O-methyl and nuclear N-methyl derivatives. From the UV spectral data the equilibrium constants of the lactam–lactim tautomerization were determined for 5-amino and 6-amino derivatives in tetrahydrofuran (THF) at various temperatures. The lactam form is more stable than that of the lactim; the enthalpy changes between two forms of 5-amino and 6-amino derivatives were estimated to be 7.9 and 6.3 kJ mol−1, respectively. The lactam and lactim dimers of these two derivatives were found to be easily formed in THF and ether. From the fluorescence spectral data the lactim dimer of 6-amino derivative was found to be formed in the lowest excited π,π* singlet state. On the other hand, the 3-amino derivative exists predominantly in the lactam monomer form in both the ground and the lowest excited π,π* singlet states.
The Pyrolysis of 1,2,3,4,6,7-Hexathia-5,8-diazocine
Authors: Kudo Yoshiyuki , Kimura Teruyoshi , Hamada Shuichi
Published: July 2006

Crystals of 1,2,3,4,6,7-hexathia-5,8-diazocine (1,4-S6(NH)2) were transformed around 363 K with a molar enthalpy change of the transformation of 2.40±0.07 kJ mol−1. Crystal systems of the two forms of 1,4-S6(NH)2 were identified to be orthorhombic (α-form) and monoclinic (β-form) below and above this temperature. Molar heat capacities of the α- and β-forms were also deduced as being 0.1950±0.001 and 0.199±0.001 kJ mol−1 K−1 at 298.15 K, respectively. The 1,4-S6(NH)2 was pyrolyzed around its apparent melting point (405 K), producing tetrasulfur tetranitride (S4N4) and tetrasulfur dinitride (S4N2) as solid intermediates, which finally decomposed into sulfur, nitrogen, and ammonia under an argon atmosphere. A stoichiometric correlation among the final products gave an overall pyrolytic equation: 1,4-S6(NH)2=3⁄4S8+2⁄3N2+2⁄3NH3. The standard enthalpy of the formation of α-form 1,4-S6(NH)2 was estimated as being 158±2 kJ mol−1 according to the observed enthalpy changes of the pyrolysis and transformation, which reasonably agreed with that calculated.
Vapor-Phase Carbonylation of Methanol over Tin-on-Active Carbon Catalysts
Authors: Yagita Hiroshi , Omata Kohji , Shikada Tsutomu , Fujimoto Kaoru
Published: July 2006

It was found that a number of metals or metal oxides showed catalytic activities for the vapor-phase carbonylation of methanol in the presence of methyl iodide (CH3I) promoter under the conditions of 250°C and 10 atm (1 atm=1.01325×105 Pa), when they were supported on active carbon. Particularly, tin and lead showed high activities. The catalytic activity of the metallic tin increased with the process time over 5 h while that of the unreduced tin catalyst increased for more than 10 h to reach the same level. The catalytic performances of the tin on active carbon were similar to those of the nickel on active carbon which have been already reported. It was suggested that the active species of the tin catalyst was some kind of metal compounds which was highly dispersed on active carbon and was able to be incorporated in the redox cycle.
The Effect of Alternating Magnetic Field on the Magnetic Anisotropic Gel Beads Immobilized Catalase
Authors: Sakai Yasuzo , Kuwahata Mitsuyoshi , Takahashi Fujio
Published: July 2006

It has been reported that magnetic anisotropic gel beads (MA gel beads) prepared by the gelation of a ferrite suspension in a static magnetic field have a property of oscillating in an alternating magnetic field. This paper presents the results concerning the application of MA gel beads to a study of immobilized enzymes. MA gel beads were prepared by the gelation of a suspension containing 5% catalase, 3.5% κ-carrageenan and 0–17% Sr-ferrite in a static magnetic field of 500–2500 Oe (1 Oe=1⁄4π×103 Am−1). The enzyme reaction was carried out in a column, which was filled with MA gel beads, by continueously flowing a solution containing H2O2 as a substrate. It was found that \ding172 MA gel beads oscillated intensely upon applying an alternating magnetic field of 100–600 Oe, 50 Hz in the column, \ding173 the concentration of O2 in the elution that passed through the column increased by 10–60% compared with that in the absence of a magnetic field, and \ding174 the concentration of O2 in the elution was influenced by the strength of the alternating magnetic field, the strength of the static magnetic field and the concentration of ferrite in the gel.
Thermal Reactions of N,N-Dimethyl-1,2-ethanediamine Complexes of Nickel(II) in the Solid State
Authors: Koner Subratanath , Ghosh Ashutosh , Ray Chaudhuri Nirmalendu
Published: July 2006

Complexes [NiL2(H2O)X]X·nH2O (L=N,N-dimethyl-1,2-ethanediamine; n=0 when X=BF4; n=1 when X=Br; n=3 when X= Cl), [NiL2(H2O)Y]·nH2O (n=2 when Y= SeO4; n=5 when Y=SO4), [NiL2(H2O)2](NO3)2·H2O and [NiL2] (ClO4)2 have been synthesized and investigated thermally in the solid state. The complexes [NiL2(H2O)Cl]Cl·3H2O, [NiL2(H2O)Br]Br·H2O, [NiL2(H2O)(SO4)]·5H2O, and [NiL2(H2O(SeO4)]·2H2O possess trans octahedral geometry and undergo deaquation-anation associated with trans→cis isomerization upon heating in the solid state whereas on deaquation the complex [NiL2(H2O)2](NO3)2·H2O retains its trans octahedral configuration. The complex [NiL2(H2O)(BF4)](BF4) possesses cis octahedral geometry and on thermal deaquation it transforms to a square planar complex. The complex [NiL2](ClO4)2 is square planar and undergoes a yellow → red thermochromic phase transition on heating (203–216°C; ΔH=6.9 kJ mol−1). The red isomer is also square planar. The species [NiLCl2], [NiL(SO4)] and NiL0.33Cl2 have been synthesized pyrolytically in the solid state from their corresponding parent diamine complexes. The complexes [NiLCl2] and [NiL(SO4)] possess octahedral geometry. NiL0.33Cl2 possesses an unusually high magnetic moment (4.1 BM at 28°C).
Reduction of CO2 by Halobacterium Halobium MMT22 to Formic Acid
Authors: Taqui-Khan Mirza Mohammad , Bhatt Jayshree
Published: July 2006

Photobiological and photoelectrochemical conversion of CO2 to formic acid was achieved by using Halobacterium halobium MMT22. The yield of formic acid increased considerably by regenerating NADH by cathodic reduction at −0.60 V or in the presence of the two-electron donor ascorbic acid. Under photoelectrochemical reduction, maximum yield of 0.2 mol of HCOOH/mg cells/h was obtained, the highest reported so far.
Reaction Mechanism between Pyruvic Acid and Aromatic Amines
Authors: Tapia I , Alcázar V , Morán J R , Grande M
Published: July 2006

The formation of the condensation products obtained when pyruvic acid and aromatic amines are allowed to react, can be explained by condensation of one mole of the imine of pyruvic acid with one mole of the enamine isomer, either through the C atom or through the N atom, followed by elimination and lactonization to give a γ-lactone carboxylate or an azlactone carboxylate, which on decarboxylation give an iminobutanolide or an azlactone respectively. Aminolysis of these cyclic intermediates led to the formation of the final products.
Liquid-Liquid Extraction of Palladium(II) with Phenylene-incorporated Tetrakis(thioether)s
Authors: Chayama Kenji , Sekido Eiichi
Published: July 2006

Extraction behaviors of palladium(II) with three cyclic and noncyclic phenylene-incorporated tetrakis(thioether)s were examined. Picrate ion as a counter anion and 1,2-dichloroethane as an extraction solvent were used. The extractability of palladium ion with the acyclic tetrakis(thioether) used in this study was higher than that with the corresponded cyclic one.
The Magnetic Properties of Copper(II) 3- and 5-Substituted 2-Pyridinolates
Authors: Emori Shuji , Furukawa Ryuichi , Nakashima Shoichi
Published: July 2006

The N,N-dimethylformamide adducts of copper(II) 3- and 5-substituted 2-pyridinolates were prepared, and then characterized by means of magnetic susceptibility and IR-spectroscopy. The variation in their magnetic moments is discussed in terms of the basicities of the parent 2-pyridones.
Photolysis of Pyridylmethyl- and Pyridiniomethylphosphonic Acids
Authors: Okamoto Yoshiki , Kokubo Ichiro , Takamuku Setsuo
Published: July 2006

Upon UV-irradiation, the C–P bond of (4-pyridylmethyl)phosphonic acid cleaved only near the isoelectronic point to give 4-methylpyridinium phosphate, while (1-benzyl-4-pyridiniomethyl)phosphonic acid underwent C–P bond cleavage above pH 4 to give 1-benzyl-4-methylpyridinium phosphate. On the other hand, the C–P bond of (2-pyridylmethyl)phosphonic acid cleaved under pH region of about 1 to 2, while (1-benzyl-2-pyridiniomethyl)phosphonic acid underwent C–P bond cleavage above pH 4.
Naphthaceno[1-12-cd:4,5-c′d′]bis[1,2]diselenole as a New Electron Donor
Authors: Miyamoto Hisakazu , Aso Yoshio , Otsubo Tetsuo , Ogura Fumio
Published: July 2006

The title compound, an isomeric TSeT, was prepared as the first example of unsymmetrical peridichalcogenide derivatives of naphthacene. Like symmetrical TSeT, it is a good electron donor and forms electrically high-conductive complexes with various electron acceptors.
Ethyl 2-(Diphenylmethyleneamino)acrylate as a Dienophile in the Synthesis of Alicyclic α-Amino Acids
Authors: Cativiela C , Fraile J M , Mayoral J A
Published: July 2006

Ethyl 2-(diphenylmethyleneamino)acrylate behaves as an excellent dienophile with cyclopentadiene. This reaction constitutes a new and improved procedure for the synthesis of 2-aminonorbornane-2-carboxylic acids.
The Structure of the Cyclodextrin Complex. XXII. Crystal Structures of Hexakis(2,6-di-O-methyl)-α-cyclodextrin Complexes with 1-Propanol and Iodine. Evidence for the Formation of Iodine-Host Charge-Transfer Complex
Authors: Harata Kazuaki
Published: July 2006

Crystal structures of hexakis(2,6-di-O-methyl)-α-cyclodextrin complexes with 1-propanol and iodine were determined by X-ray analysis. Crystals of both complexes are isomorphous and the space group is P21 with cell dimensions: a=14.136(2), b=10.680(1), c=21.479(2) Å, and β=106.00(1)° for the 1-propanol complex and a=14.124(2), b=10.667(2), c=21.443(3) Å, and β=106.29(1)° for the iodine complex. The structures were solved by the R-map method combined with the rigid-body least-squares technique and refined by the block-diagonal least-squares method to the R-value of 0.058 for the 1-propanol complex and 0.094 for the iodine complex. The host molecules are arranged in a herring-bone fashion to form a typical cage-type packing structure. Both guest molecules are included within the “cage” which is created by the block of both ends of the annular host cavity by adjacent molecules. The 1-propanol molecule is in van der Waals contact with the inside wall of the host cavity, whereas the iodine molecule forms a charge-transfer complex with an O(3)H hydroxyl group of the adjacent host.
Electronic Structure of β-Carboline Anhydro-Bases
Authors: Aihara Jun-ichi , Ichikawa Hiroshi , Tokiwa Hiroaki , Okumura Yasuaki
Published: July 2006

β-Carboline anhydro-bases generally have a large positive topological resonance energy although they apparently disobey the rule of topological charge stabilization (TCS rule). π-Electron densities and molecular geometries calculated at the STO-3G+ level support the view that the dipolar aromatic structure contributes appreciably to the stability of β-carboline anhydro-bases. However, these molecules are still worse in energy than the isomeric β-carbolines. Protonated anhydro-bases or β-carbolinium ions conform to the TCS rule. All biogenic β-carboline anhydro-bases must be protonated in living organisms.
A Conductance Study of Macrocyclic Schiff Base Metal(II) Complexes in Methanol
Authors: Liu Jianhua , Masuda Yoshitaka , Sekido Eiichi
Published: July 2006

The first ionic association constants between five macrocyclic Schiff base metal(II) complexes (cation and perchlorate or thiocyanate anion) were determined by conductometric measurements in methanol at 25 °C by using a modified Onsager limiting equation, according to Fuoss and Edelson method. The limiting equivalent conductivities of the chelate cations of these complexes were calculated. These results were used to evaluate the performance of coated-wire perchlorate ion-selective electrodes (PCWE) based on these complexes.