bluuebunny/crossref_metadata_2025 huggingface dataset:
Photo- and Thermally-induced Radical Rearrangements of 6-Methyl- and 4,4,6-Trimethylcholest-5-en-3β-ol
Authors: Suginome Hiroshi , Maeda Norio , Seki Yoshikatsu , Orito Kazuhiko
Published: July 2006

The irradiation of 6-methylcholest-5-en-3β-ol in benzene containing mercury(II) oxide and iodine gave 3α,5-epoxy-6-methylene-A-homo-4-oxa-5α-cholestane (23%) and 2-iodo-6-methyl-A-nor-2,3-secocholest-5-en-3-yl formate (32%). The thermally-induced reaction at 55–60 °C gave the former in a 16% yield. The corresponding photo-reaction of 4,4,6-trimethylcholest-5-en-3β-ol, however, gave 4,6-dimethyl-4-methylene-3,4-secocholest-5-en-3-al.
The Racemization of Glutamic Acid Induced by Aliphatic Aldehydes
Authors: Yamamoto Mihoko , Ozaki Hiroshi , Tai Akira , Izumi Yoshiharu
Published: July 2006

The real catalytic species in the racemization of glutamic acid induced by acetaldehyde was investigated and found to be 2-butenal produced in situ from acetaldehyde.
An MO Study of the Photochemical Electrocyclic Isomerization between Vinylketene and Cyclobutenone
Authors: Kikuchi Osamu
Published: July 2006

The MINDO/3 CI potential energy surfaces of the vinylketene–cyclobutenone system suggest that the cyclization of vinylketene occurs from the π→π* state via the zwitterion, in which the negative charge is located on the 90°-twisted methylene carbon atom, while the reverse reaction proceeds via a diradical structure.
Stereochemistry of Friedel-Crafts Reaction of Benzene with Optically Active 2-Methyloxetane
Authors: Segi Masahito , Takebe Masaki , Masuda Shinji , Nakajima Tadashi , Suga Sohei
Published: July 2006

The Friedel-Crafts alkylation of benzene with (+)-2-methyloxetane in the presence of Lewis acids (AlCl3, SnCl4, and TiCl4) gave 3-phenyl-1-butanol with 20–60% inversion of configuration at the reaction center and a mixture of 4-chloro-2-butanol and 3-chloro-1-butanol in optically active form as the by-products. These by products were formed by the attack of the chlorine atom in Lewis acid. The stereochemical course of the reaction to 3-chloro-1-butanol varied with the kind of catalyst, i.e., inversion with AlCl3 or TiCl4 and retention with SnCl4. The addition of nitromethane to the reaction system promoted the retentive ring-opening to 3-chloro-1-butanol.
ESR Studies of Cobalt(II) in [TMPD+]2[Ni(mnt)2] and [TMPD+]2[Pt(mnt)2](TMPD+: N,N,N′,N′-Tetramethyl-p-phenylenediamine Cation, mnt: 1,2-Dicyano-1,2-ethylenedithiolato)
Authors: Setoi Tomoyoshi , Inoue Motomich , Nakamura Daiyu
Published: July 2006

The Co(II) and triplet exciton ESR spectra of Co(II)-doped [TMPD+]2[Ni(mnt)2] and [TMPD+]2[Pt(mnt)2] were observed at different temperatures. The triplet exciton signals of the solid solutions yielded practically the same ESR parameters as those of the pure Ni(II) and Pt(II) complexes. The Co(II) spectra showed a wellresolved hyperfine structure, each component line of which became broad with increasing temperature. This can be interpreted in terms of exciton transfer from TMPD+ lattices to the metal ions.
The Insertion Reaction of NH Singlet Radicals into the C–H Bonds of Cyclopropane and Isobutane in the Liquid Phase
Authors: Hamada Jun-ich , Tsunashima Shigeru , Sato Shin
Published: July 2006

Hydrogen azide was photolyzed in liquid cyclopropane at the temperature of Dry Ice–methanol. The main products observed were nitrogen, cyclopropylamine, and ammonia. The relative yields of the products depended slightly on the concentration of hydrogen azide. The results were then compared with those obtained with paraffin and olefin. The isobutane solution of hydrogen azide was photolyzed at 0 °C. The products observed were the same as those obtained at the temperature of Dry Ice-methanol. The relative yields of the products and the concentration dependence, however, were different.
Solvent Effects on the Fluorescence Quantum Yields and Lifetimes of 1- and 2-Acetyl- or Benzoylanthracenes
Authors: Tamaki Takashi
Published: July 2006

The fluorescence quantum yields and lifetimes of 1- and 2-acetyl- or benzoylanthracenes were measured in various degassed solvents at room temperature. The natural fluorescence lifetime was evaluated to be 30–40 ns, depending a little on the compounds, but little on the solvent. This strongly supports the recent finding that the lowest excited singlet state of the acylanthracenes is of a ππ* character. On the basis of triplet-yield measurements, it was also confirmed that the low fluorescence yield in nonpolar solvents is due to an efficient intersystem crossing to an upper triplet state.
The Photoassociation of 1- and 2-Acetylanthracenes with Methanol
Authors: Tamaki Takashi
Published: July 2006

The effect of small amounts of methanol (≤0.34 mol dm−3) upon the absorption and fluorescence spectra of 1- and 2-acetylanthracenes in hexane was investigated. While the formation of a 1 : 1 hydrogen-bonded complex in the ground state was revealed by the isosbestic points of the absorption spectra, the change in the fluorescence spectra was indicative of the photogeneration of a highly associated complex which includes at least two alcohol molecules. On the assumption that the excited 1 : 1 complex further associates with an alcohol molecule, the computer simulation by the least-squares method provided a good fit of the observed concentration dependence of methanol upon the fluorescence quantum yield. The photokinetic parameters and the thermodynamic quantities were evaluated from the parameter values.
Correlation between Critical Solution Phenomena and Ultralow Interfacial Tensions in a Surfactant/Water/Oil System
Authors: Kunieda Hironobu , Shinoda K\={o}z\={o}
Published: July 2006

A three-phase region consisting of surfactant (D), water (W), and oil (O) phases appeared due to the superposition of two critical phenomena of D–W and O–D in a nonionic surfactant/water/oil system. Three interfacial tensions, γO–W, γO–D and γD–W, among the three phases were determined at various temperatures. The generalized Antonoff’s rule (γO–W=γO–D+γD–W) holds approximately in the three-phase region. γO–D and γD–W disappear at the respective critical solution temperatures, and ultralow interfacial tensions are attained in the vicinity of both critical temperatures. The oil–water interfacial tension, γO–W, reaches its minimum in the midst of the temperature range of the three-phase region, and the narrower the temperature range of the three-phase region, the lower the interfacial tension. The correlation between the interfacial tensions and the types of emulsions is also discussed.
A Proton Magnetic Resonance Study of Dialkyl Terephthalate Dianions
Authors: Hirayama Masatoshi , Kaneko Mitsuo
Published: July 2006

NMR spectra were observed for green solutions formed from dimethyl, diethyl, and diisopropyl terephthalates in contact with sodium metal in THF-d8  in vacua at ambient probe temperature. A comparison of proton chemical shifts with excess charge densities calculated by the CNDO MO method supports that the green species are disodium salts of π-dianions.
Anion Exchange Separation of Hard Acid-metals Using HF–H3BO3 Media
Authors: Adachi Takeo
Published: July 2006

The properties of HF–H3BO3 media and the distribution coefficients of eighteen metals have been investigated to achieve the separation of hard acid-metals by the anion exchange method. As the addition of boric acid to hydrofluoric acid solution reduces the free fluoride ion concentration to about one hundredth, it is possible to control the formation of metal fluoride complexes in a way favorable for the separation. The BF4− and BF3OH− produced in this media are adsorbed strongly to the resin and reduce the relative adsorbabilities of metal fluoride complexes remarkably. Using these properties of HF–H3BO3 media and the adsorbabilities of other anions, a new anion exchange method for the separation of hard acid-metals has been proposed. The new method is especially useful for the separation of titanium, zirconium, niobium, and tantalum. Distribution coefficients and elution behaviors of metal ions are not affected by the increase of the amount of metals because of the buffer action relating to the fluoride in HF–H3BO3 media.
Influences of the Lanthanoid Contraction on the Thermal Dehydration Reactions of Lanthanoid(III) Malonate Hydrates
Authors: Muraishi Kazuo , Nagase Kenzo , Kikuchi Masae , Sone Kozo , Tanaka Nobuyuki
Published: July 2006

The thermal dehydration reactions of lanthanoid(III) malonate hydrates Ln2mal3·nH2O (Ln=Ce–Lu; mal=CH2(COO)2; n=6 for Ce–Eu and 8 for Gd–Lu) were investigated mainly by the thermogravimetries under conventional conditions and in atmosphere of water vapor at a constant reduced pressure and a superslow heating rate. The latter conditions were useful especially to detect the formation of new intermediate hydrates, and to determine the dehydration temperatures with accuracy. The main features of the results could be reasonably understood in view of the effects of the lanthanoid contraction.
The Preparation of Protoheme Mono-N-[5-(2-methyl-1-imidazolyl)pentyl]amide and Its Oxygenation
Authors: Tsuchida Eishun , Nishide Hiroyuki , Sato Yoshinori , Kaneda Manabu
Published: July 2006

Iron(II)protoporphyrin IX N-[5-(2-methyl-1-imidazolyl)pentyl]amide ethyl ester (1) and its derivatives (2–4) were prepared. They predominantly form pentacoordinate heme complexes in organic and aqueous solutions, based on their 2-methylimidazole-ligand and spacer N-pentylamide groups. Oxygen adducts of 1–4 were rapidly formed on exposure to oxygen in N,N-dimethylformamide (DMF) at −30 °C, and their life-times were more than 30 min.
The Effect of Polyhydric Alcohols on the Thermal Denaturation of Lysozyme as Measured by Differential Scanning Calorimetry
Authors: Fujita Yukihisa , Iwasa Yasuchika , Noda Yukinao
Published: July 2006

The thermal denaturation of lysozyme in aqueous solutions of polyhydric alcohols at pH 2 was investigated by differential scanning calorimetry (DSC). The polyhydric alcohols employed were inositol, sorbitol, xylitol, erythritol, glycerol, and ethylene glycol. These alcohols tended to enhance the thermal stability of lysozyme; both the temperature and the enthalpy of denaturation increased almost linearly with increasing alcohol concentration. The increase in denaturation temperature at a given alcohol concentration was a linearly increasing function of the number of hydroxyl groups per alcohol molecule. The denaturation enthalpy at identical temperature increased only slightly by the addition of polyhydric alcohol. The hypothesis may be supported that the dominant mechanism by which polyhydric alcohols stabilize proteins to thermal denaturation is through their effect on the water structure, which determines the strength of the hydrophobic interactions between the nonpolar groups of the protein.
New Synthesis of Megastigma-4,6,8-trien-3-ones, 3-Hydroxy-β-ionol, 3-Hydroxy-β-ionone, 5,6-Epoxy-3-hydroxy-β-ionol, and 3-Oxo-a-ionol
Authors: Takazawa Osamu , Tamura Hiroshi , Kogami Kunio , Hayashi Kazuo
Published: July 2006

The Lewis acid-catalysed reaction of 1-trimethylsiloxy-1,3-cyclohexadienes with aldehydes and trialkyl orthoformates afforded the corresponding 4-substituted 2-cyclohexenones. A new reaction of 2,4,6-trienones with m-chloroperbenzoic acid followed by the reduction with zinc in acetic acid gave 7-hydroxy-3,5-dienones. Utilizing these efficient reactions, megastigma-4,6,8-trien-3-ones, 3-hydroxy-β-ionol, 3-hydroxy-β-ionone, 5,6-epoxy-3-hydroxy-β-ionol, and 3-oxo-α-ionol were successfully synthesized.
Oxidative S-Dealkylation Reaction of Sulfide Catalyzed by Co(II)(bzacen)
Authors: Watanabe Yoshihito , Numata Tatsuo , Oae Shigeru
Published: July 2006

In the oxygenation reaction of alkyl sulfides with Co(II)(bzacen)–O2 system, oxidative S–C bond cleavage (S-dealkylation) was found to take place exclusively. The reactivity of S-dealkylation reaction was dependent markedly on both acidity of α-methylene and steric hindrance of alkyl sulfide. The peroxo-Co(III) species is presumed to be the intermediate in this S-dealkylation reaction.
Manufacture of High Pure Titanium(IV) Oxide by the Chloride Process. I. Kinetic Study on Leaching of Ilmenite Ore in Concentrated Hydrochloric Acid Solution
Authors: Tsuchida Hisashi , Narita Eiichi , Takeuchi Hitoshi , Adachi Masahiro , Okabe Taijiro
Published: July 2006

Kinetic study of the leaching of powdered ilmenite ore was carried out in highly concentrated hydrochloric acid (11.3–11.6 mol dm−3) at temperatures of 30 to 80 °C. The changes in shape and grain size of the ore particles with progress of the leaching was simultaneously observed with X-ray diffraction and electron microscope techniques. Titanium and iron were dissolved in a nearly stoichiometric ratio; the rate of the dissolution was significantly affected by the temperature of the acid solutions. From the analysis of the dissolution rates on the basis of the core-model, it was found that the dissolution rates at temperatures of 30 to 50 °C were well expressed by the rate equation based on the rate-determining step of the surface chemical reaction. The apparent activation energies were 81.2 kJ mol−1 for titanium and 73.2 kJ mol−1 for iron. The rate-determining step of the dissolution was changed at a temperature of about 50–60 °C; the dissolution rates at temperatures of 60 to 80 °C were limited by the diffusion of the dissolved metal ions through a residual layer of the ore. However, the rates after 2 or 3 h at high temperatures deviated from the rate equation because of the precipitation of hydrous titanium(IV) oxide on the surface of the ore by hydrolysis of the dissolved titanium(IV) ion.
Reaction of Electroehemically Generated Radical Anion of Thioketone with Alkylating Agents
Authors: Yasui Shinro , Nakamura Kaoru , Ohno Atsuyoshi , Oka Shinzaburo
Published: July 2006

Electrochemically generated anion radicals of thioketones were allowed to react with alkyl halides (or tosylate). Electronic structure of the anion radical is discussed on the basis of the products.
Studies on Heteropentalenes. IV. Heteroannelations to Pyrrolo-[2,1-b]benzothiazole and Pyrrolo[2,1-b]thiazoles
Authors: Abe Noritaka , Nishiwaki Tarozaemon , Omori Toshimasa , Harada Emiko
Published: July 2006

2,3-Dibenzoylpyrrolo[2,1-b]benzothiazole (2) and 6,7-dibenzoylpyrrolo[2,1-b]thiazoles (5a–b) have been synthesized by utilizing the cycloaddition reactions of imidazo[2,1-b]benzothiazole and imidazo[2,1-b]thiazoles, respectively, with dibenzoylacetylene followed by the elimination of a nitrile from each of the cycloadducts. Heteroannelations to 2 and 5 have been achieved by their reactions with hydrazine, aminoacetonitrile, ethyl glycinate, and phosphorus pentasulfide. The annelations by the second and third reagents proceed fairly regioselectively. Facile dimerizations of thieno[3′,4′:3,4]pyrrolo[2,1-b]benzothiazole and thieno[3′,4′:3,4]pyrrolo[2,1-b]thiazoles to be produced by the reactions with the last reagent are also described.
Experimental and Calculated Magnetic Circular Dichroism Spectra of Iron(II) Low Spin Hemoglobin and Myoglobin with CO, NO, and O2
Authors: Yamamoto Takao , Nozawa Tsunenori , Kaito Akira , Hatano Masahiro
Published: July 2006

The ratios of the apparent Faraday A terms to the dipole strengths (A′⁄D) were obtained from the experimental magnetic circular dichroism (MCD) data for the iron(II) low spin derivatives of human hemoglobin and its α and β chains, and myoglobins (whale and bovine). The observed MCD peak height and trough depth exhibit the decreasing order of CO>O2>NO in the Soret band and O2>CO>NO for the Q band. The moment analysis also showed the decreasing order of the A′⁄D values of CO>O2>NO in the Soret bands for all hemoglobin and myoglobin derivatives experimentally studied. The molecular orbital calculation of the porphyrin π electron system based on the PPP CI approximation method demonstrated that the calculated spectra for the pyrrole nitrogen core-charge of 1.5 showed characteristics for the CO complex of hemoglobin and myoglobin, and that the NO and O2 complexes could be simulated by the calculations for the core charge values smaller than 1.5 (i.e. 1.4–1.3). These results suggest that the change in the porphyrin π electronic state which is caused by the electronic interaction between the diatomic molecule such as CO, NO, or O2 and the heme iron can be explained by the change in the σ core charge in the pyrrole nitrogen possibly through changes in the electronic states of the heme iron.
Surface Free Energies of Two Kinds of Graphite Fluorides, (CF)n and (C2F)n
Authors: Watanabe Nobuatsu , Nakajima Tsuyoshi , Ohsawa Noboru
Published: July 2006

The surface free energies of two kinds of graphite fluorides, (CF)n and (C2F)n, were estimated from the contact angles of several liquids. The contact angles of water on flaky (CF)n and (C2F)n were 117° and 116°, respectively, being slightly larger than that for poly(tetrafluoroethylene), while the values for tablets of powdery (CF)n and (C2F)n were 143° and 141°, respectively, which indicates that powdery graphite fluoride is hardly wetted by water. From the contact angles obtained, the surface free energies were estimated to be ca. 18 mJ/m2 for both flaky (CF)n and (C2F)n, ca. 2 mJ/m2 for powdery (CF)n and ca. 3 mJ/m2 for powdery (C2F)n. These differences depend on the surface conditions such as the packing of fluorine atoms, the roughness and porosity. From the contact angles for the tablets of (CF)n–polyethylene mixtures, it is suggested that the anode effect in the fluorine or aluminium electrolysis takes place when the surface of carbon anode is partially covered by graphite fluoride.
Structural Studies of Partially Oxidized One-dimensional Bis(oxalato)-platinate Salts Containing Bivalent Cations: Ni0.84[Pt(C2O4)2]·6H2O
Authors: Kobayashi Akiko , Kondo Hidetaka , Sasaki Yukiyoshi , Kobayashi Hayao , Underhill Allan E , Watkins David M
Published: July 2006

Fundamental structure, kF and 2kF satellite reflections, and electrical properties of Ni0.84[Pt(C2O4)2]·6H2O (Ni–OP) were determined. Complex Ni–OP crystallizes in the orthorhombic space group Pccn with cell parameters of a=14.296(2), b=16.387(3), and c=5.671(1) Å and Z=4. Ni–OP is essentially isostructural with Mg–OP (Mg0.82[Pt(C2O4)2]·5.3H2O) and Co–OP (Co0.83[Pt(C2O4)2]·6H2O). The space group of Mg–OP and Co–OP is Cccm. Owing to the change in the space group, there are two independent Pt chains in Ni–OP. X-Ray studies of M–OP (M=Co, Ni) show that there exist strong kF satellite spots and weak 2kF spots. One M2+ cation is vacant per period of the lattice modulation wave of the platinum chain, λ2kF. The periodic cation defect induces the kF modulation waves. The 2kF waves do not have a Peierls origin but are induced by the kF modulation wave. A second order phase transition is observed at about 305 K above which the 2kF spots disappear.
Cobalt(II)-substituted Horseshoe Crab Hemocyanins
Authors: Suzuki Shinnichiro , Kino Jun , Nakahara Akitsugu
Published: July 2006

The horseshoe crab Co(II) hemocyanins were prepared by dialyses of Tachypleus tridentatus, Tachypleus gigas, Limulus polyphemus, and Carcinoscorpius rotundicauda apohemocyanins against Tris–HCl buffer (pH 8.0) containing Co(II) ion. The amounts of Co(II) introduced into apohemocyanins reached almost 100% of the total sites for copper ion in native hemocyanins. However, all the four Co(II) hemocyanins did not take up oxygen molecule at all. The extremely similar spectral data for the four species revealed that there is no essential difference in the structure of the respective active sites. Both the two Co(II) ions at an active site are in the high spin state and in an distorted tetrahedral geometry, having no such ligating groups as cysteinyl or methionyl sulfur, but at least three nitrogenous ligands, probably histidine imidazoles. On the basis of these data, the environment of active site in native horseshoe crab hemocyanin is discussed.
A Potentiometric Study on Mixed Ligand Cadmium(II) Complexes with 2-Pyridinecarboxylic Acid and 2-Aminoalkanoic Acids
Authors: Matsui Haruo , Ohtaki Hitoshi
Published: July 2006

Formation constants of cadmium(II) complexes with 2-pyridinecarboxylic acid (Hpic) were determined in aqueous solutions containing 3 mol dm−3 LiClO4 as a constant ionic medium at 25 °C by potentiometric titrations. On the basis of the formation constants of the complexes thus determined and those of the 2-aminoalkanoate complexes previously obtained, formation constants of mixed ligand cadmium(II) complexes CdL(pic) were determined, where L− denotes a 2-aminoalkanoate ion such as glycinate (gly−), α-alaninate (ala−), 2-aminobutanoate (but−), 2-aminopentanoate (pen−), or 2-aminohexanoate (hex−) ion. The formation constants logβ111=log {[CdL(pic)]/([Cd2+][L−][pic−])} of the 1:1:1 mixed ligand cadmium(II) complexes are: Cd(gly)(pic), 8.88; Cd(ala)(pic), 8.47; Cd(but)(pic), 8.42; Cd(pen)(pic), 8.73; and Cd(hex)(pic), 8.76. The equilibrium constant of the reaction between Cd(gly)+ and pic− was larger than that between Cd(pic)+ and gly−, and much larger than the equilibrium constants between CdL+ and L′− previously studied, where L− and L′− are 2-aminoalkanoate anions.
Solute-Solvent Interactions in Ion Pair Extraction of Tetraalkylammonium Iodides. II. The Effect of Hydration of Iodide in Organic Solvents on the Extraction Constant
Authors: Ito Kazuaki , Iwamoto Etsuro , Yamamoto Yuroku
Published: July 2006

Solubilities of tetraalkylammonium iodides Et4NI, Pr4NI, and Bu4NI in nitrobenzene, in water, and in their mutually saturated solvents, and of Pr4NI in 1,1-dichloroethane and in its water saturated solvent were measured at 25 °C. Conductances of Et4NI, Pr4NI, and Bu4NI in nitrobenzene and Bu4NI in 1,1-dichloroethane, 1,2-dichloroethane, and dichloromethane have also been measured at 25 °C. A small amount of water in organic solvents increases the solubilities of the salts roughly twice those in pure solvents and decreases the association constants around 15% while a small amount of organic solvent in water gives a slight effect. Effects of mutual saturation of water and organic solvent on extraction equilibria of R4NI were discussed in terms of the selective hydration of the iodide.
Synthesis and Cation-complexing Ability of Oxo Crown Ethers
Authors: Matsushima Kenji , Kawamura Norio , Nakatsuji Yohji , Okahara Mitsuo
Published: July 2006

3-Substituted 2-oxo crown ethers and a novel dioxo crown ether with a point symmetry were synthesized by the cyclization of the corresponding substituted oligoethylene glycol monocarboxymethyl ethers using benzenesulfonyl chloride in the presence of alkali metal carbonates. The reaction mechanism was discussed. Their stability constants toward sodium and potassium cations were determined and the relation between their structures and complexing properties was discussed.
The Preparation of Optically Pure 3-Hydroxyalkanoic Acid. The Enantioface-differentiating Hydrogenation of the C=O Double Bond with Modified Raney Nickel. XXXVII.
Authors: Nakahata Masaaki , Imaida Motomasa , Ozaki Hiroshi , Harada Tadao , Tai Akira
Published: July 2006

The enantioface-differentiating hydrogenation of methyl 3-oxoalkanoate (CH3(CH2)nCOCH2COOCH3, n=0, 6, 8, 10, 12) over the (R,R)-tartaric acid–NaBr–modified Raney nickel catalyst ((R,R)-TA–NaBr–MRNi) gave methyl (R)-3-hydroxyalkanoate (CH3(CH2)nCH(OH)CH2COOCH3, n=0, 6, 8, 10, 12) in an average optical yield of 85%. After the methyl ester had been converted to dicyclohexylammonium salt of 3-hydroxyalkanoic acid, the salt was recrystallized three times from acetonitrile and then treated with acid to give optically pure (R)-3-hydroxyalkanoic acid (CH3(CH2)nCH(OH)CH2COOH, n=0, 6, 8, 10, 12) in a reasonable yield. From the hydrogenation product with (S,S)-TA–NaBr–MRNi, optically pure (S)-3-hydroxyalkanoic acid was obtained by the same process as above.
Stereospecific Synthesis of (2Z,4E,6E)-3,7,11-Trimethyl-2,4,6,10-dodecatetraene [trans(C10)-Allofarnesene]
Authors: Miyaura Norio , Suginome Hiroshi , Suzuki Akira
Published: July 2006

The stereospecific synthesis of the title acyclic sesquiterpene, isolated from Perilla frutscens f. viridis Makino (Japanese name, Aojiso) by the palladium-catalyzed cross-coupling of 2-(4,8-dimethyl-1,3,7-nonatrienyl)-1,3,2-benzodioxaborole with (Z)-2-bromo-2-butene, is described. The benzodioxaborole was prepared by the hydroboration of 4,8-dimethyl-3,7-nonadien-1-yne, newly prepared via three steps from geranial, with 1,3,2-benzodioxaborole.
Lanthanoid Shift Reagents. Synthesis and Spectral Studies
Authors: Iftikhar Khalid , Sayeed Mohammad , Ahmad Naseer
Published: July 2006

The seven coordinate adducts of [Ln(fod)3]chelates are described. The NMR spectra of diamagnetic and paramagnetic adducts have been discussed. The europium, praseodymium and ytterbium adducts have been scanned as potential shift reagents and these seven coordinate adducts produce large dipolar shifts in the proton magnetic resonances of organic moieties. The dipolar shift produced by [Eu(fod)3(pz)] in the spectrum of benzyl alcohol is different from that reported. Some interelectronic and spectral parameters (\barβ, b1⁄2, and δ) have been calculated. Ligand field parameter (Tλ) and oscillator strengths have been computed and discussed.
Efficiency of Noble Metal Electrodes for Zirconia Oxygen Sensors in Detecting Oxygen at Lower Temperatures
Authors: Arakawa Tsuyoshi , Saito Akira , Shiokawa Jiro
Published: July 2006

Metal Au, Ag, or Pt was deposited as electrode on the closed end of a stabilized electrolyte tube in the ZrO2 oxygen sensor, and emf of the cell, O2|m|ZrO2–Y2O3|m|O′2; (m=Au, Ag, Pt) with PO2=8.8 and PO′2=159 Torr (1 Torr=133.322 Pa), was measured as a function of temperature between 150 and 950 °C. For cells with Ag electrodes, a good agreement is found between theoretical and measured emf’s at lower temperatures (ca. 340 °C).
The Enhancement of Formose Formation with 2-Hydroxyacetophenone. A Mechanism Involving Aldol and Retro-aldol Reactions
Authors: Sakai Tomoya , Ishizaki Masahiko , Goto Masafumi
Published: July 2006

The rapid aldol addition of formaldehyde to 2-hydroxyacetophenone (HAP), an efficient accelerator for formose formation, took place to yield addition products of HAP with one and two molecules of formaldehyde at 35 °C in an aqueous 40% methanol mixture of formaldehyde, HAP, and Ca(OH)2. No further addition product with more than two molecules of formaldehyde attached to HAP was detected throughout the reaction. On the contrary, benzaldehyde and benzoic acid were formed, accompanied by formose sugars. The initial molar amount of HAP corresponded to the sum of the compounds substituted with the phenyl group including benzaldehyde and benzoic acid. The retro-aldol reaction of the HAP derivatives is likely to be involved in the overall reaction to yield glycolaldehyde or trioses, which are good accelerators for formose formation.
An Application of Molecular Mechanics Calculations on Thermal Reactions of Ten-membered Ring Sesquiterpenes
Authors: Terada Yukimasa , Yamamura Shosuke
Published: July 2006

Molecular mechanics calculations were successfully carried out to evaluate relative stabilities of each conformation of germacrenes in their ground states and transition states. In the calculation of such a transition state model as shown in Scheme 1, the parameters for partial bonds were taken as mean values of those for a reactant and a product. Thus, the calculation results on each transition state model indicate that the elemenes are formed from the corresponding germacrenes through the most stable transition state (CC), regardless of the most stable conformers in ground state. Calculations were also carried out on ground and transition states of acoragermacrone and isoacoragermacrone, both of which have an α,β-unsaturated carbonyl system. The calculation results on each transition state model indicate that shyobunone (5) and epishyobunone (6) both are formed from acoragermacrone through the corresponding transition states [5 from CC; 6 from C′C′ and C′T] in relative ratio (5/6=87/13) which is in good agreement with that of the experimental result (5/6=84/16). In the case of isoacoragermacrone, molecular mechanics calculations indicate that the preisocalamendiol-type transition state model is more favorable than the models corresponding to the Cope rearrangement products.
Fluoride Salts on Alumina as Reagents for Alkylation of Phenols and Alcohols
Authors: Ando Takashi , Yamawaki Junko , Kawate Takehiko , Sumi Shinjiro , Hanafusa Terukiyo
Published: July 2006

The effectiveness of alkali metal fluorides impregnated on alumina as a reagent for promoting alkylation was optimized with respect to the metal cation, the amount of impregnation, and the reaction solvent. Potassium or caesium fluoride on alumina in acetonitrile or 1,2-dimethoxyethane was concluded to be the best reaction system for general use. O-Alkylation of substituted phenols, primary and secondary alcohols, and a glycol was carried out mostly in good yields under mild conditions with simple experimental procedures.
Restricted Rotation Involving the Tetrahedral Carbon. XLII. Barriers to Rotation and Populations of Rotamers in 9-[2-(Substituted methyl)-1-napthyl]fluorenes
Authors: Saito Ryo , Oki Michinori
Published: July 2006

Rotational barriers in 9-[2-(substituted methyl)-1-naphthyl]fluorenes are found not significantly affected by the substituent on the methyl group, ΔG\eweq’s being ca. 29 kcal/mol at 373 K. Populations of sp- and ap-rotamers at equilibriums show that the sp form is favored to some extent and the results are attributed to entropy factor. OH···π interaction is detected in the ap form of 9-(2-hydroxymethyl-1-naphthyl)fluorene.
The Lowest Triplet State of 2-Methylpyrazine
Authors: Watanabe Takeshi , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

The infrared and Raman spectra of 2-methylpyrazine were studied. An assignment was given for all fundamental vibrations based on the polarization behavior of the spectral bands and on the normal coordinate analysis. The magnetic effect on the phosphorescence lifetime and the time-resolved and polarized phosphorescence spectra of this molecule were investigated at 1.4 K. From the analysis of the phosphorescence, (1) the short lifetime phosphorescence was assigned to the emission arising from the most emissive y″ sublevel, as in the case of pyrazine, (2) the long lifetime phosphorescence was assigned to the emissions arising from the x and z″ sublevels, whose lifetimes were roughly equal to each other and (3) the 0-0 and totally symmetric vibronic bands, and the out-of-plane vibronic bands observed in the long lifetime phosphorescence, were ascribed to the z″ and x sublevel emissions, respectively.
Conformational Characterization of S-Methyl Dithiocarbazate by Infrared Spectra and Vibrational Assignments
Authors: Manogaran Sadasivam , Sathyanarayana Dixit Narayanarao
Published: July 2006

Infrared spectra are recorded for S-methyl dithiocarbazate and its N-deuterated compound in two molecular conformations in the solid state and in solution between 4000 and 30 cm−1. The assignments have been supported from a complete normal coordinate analysis; the conformation sensitive bands of the –CSNHNH2 grouping are discussed. The assignments are compared with those of related molecules to check the internal consistency and to obtain the pattern of the characteristic bands of thiocarbazoyl (–CSNHNH2) group. The magnitudes of the C–N and S–CH3 torsional barriers are estimated from the force constants.
Spectrophotometric Determination of Osmium by Ternary Complex Formation with Thiocyanate and Rhodamine 6G
Authors: Jaya Sambamurthy , Ramakrishna Tiruvesaloor Venkatrama
Published: July 2006

Osmium in trace amounts is determined by use of its reaction with thiocyanate and Rhodamine 6G to form an ion-association complex at pH 3.0. Aided by stabilization with gelatin, measurement of absorbance at 565 nm permits the determination of osmium in the range 0.04–1.2 ppm. The colour system is very stable and provides a molar absorptivity of 6.84×104 l mol−1 cm−1. A few elements interfere and methods are suggested for handling them except ruthenium and rhodium.
A Convenient Synthesis of Linear 2-Methylpyranochromones
Authors: Ahluwalia Vinod Kumar , Jain Anjula , Gupta Ranjna
Published: July 2006

A convenient synthesis of linear 2-methylpyranochromones, viz., spatheliachromen(5-hydroxy-2,2,8-trimethyl-2H,6H-benzo[1,2-b:5,4-b′]dipyran-6-one), O-methylspatheliachromen (5-methoxy-2,2,8-trimethyl-2H,6H-benzo[1,2-b:5,4-b′]dipyran-6-one) (8) and O-methylallopteroxylin (5-methoxy-2,8,8-trimethyl-4H,8H-benzo[1,2-b:3,4-b′]dipyran-4-one) is described by blocking the eighth position of the corresponding 7-propargyl ether derivative 7-(1,1-dimethyl-2-propynyloxy)-8-iodo-5-methoxy-2-methyl-4H-1-benzopyran-4-one with iodine followed by thermal cyclization. The linear pyranochromones 2,2,8-trimethyl-2H,6H-benzo[1,2-b:5,4-b′]dipyran-6-one and 8 are also synthesized starting with the easily available appropriate 3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-7-ols following the steps of Claisen condensation with ethyl acetate, cyclization with ethanolic sulfuric acid followed by dehydrogenation with NBS.
Liquid Crystals of Binary Mixtures. Induction of Nematic Phase by Intermolecular Charge-transfer Interaction and Application of Solid-solution Model
Authors: Iida Yôichi
Published: July 2006

Nematic phase induced by binary mixture consisting of electron donor and acceptor was examined by using modified solid-solution model. The experimental results of Araya and Matsunaga were explained by this approach, and the charge-transfer interaction energy between donor and acceptor in the nematic phase was estimated by analyzing their phase diagrams.
Association of Inclusion Compounds of β-Cyclodextrin in Aqueous Solution
Authors: Hamai Sanyo
Published: July 2006

Inclusion compounds in the systems naphthalene–β-cyclodextrin (CDx) and 2-methoxynaphthalene (MN)–o-dicyanobenzene (DB)–β-cyclodextrin in aqueous solution were studied by means of absorption and fluorescence spectra. In the former system a naphthalene excimer fluorescence was observed. By the analyses of the concentration dependence of the absorption spectra and the excimer fluorescence intensities, the species responsible for the excimer fluorescence is identified as a 2:2 inclusion compound which is formed by association of two 1:1 naphthalene–CDx inclusion compounds, not a 2:1 inclusion compound in which two naphthalene molecules enter into the cavity of one CDx molecule. In the latter system, absorption and fluorescence spectra due to a charge transfer complex of MN with DB were observed. By analyses similar to the naphthalene case, the existence of a 1:1:2 association compound formed between a MN–CDx inclusion compound and a DB–CDx inclusion compound is confirmed. Fluorescence quenching by I− and IO3− was also studied for the inclusion compounds in both systems.
Electron Transfer in the Quenching of Triplet States of Zinc Phthalocyanine and Methylene Blue by the Use of Fe(III), Co(III), and Organic Oxidants
Authors: Ohno Takeshi , Kato Shunji , Lichtin Norman N
Published: July 2006

The mechanism of the quenching of the triplet state of zinc phthalocyanine (ZnPc) and Methylene Blue (MB+) by low-spin complexes of Fe(III) and Co(III) and aromatic oxidants was studied. The quenchers studied included FeIII(CN)63−, FeIII(CN)4(2,2-bipyridyl)−, FeIII(CN)2(2,2-bipyridyl)+, ferrocenium ion, CoIII(2,2′:6′-2″-terpyridyl)3+, CoIII(1,10-phenanthroline)3+, dimethylviologen, 1,4-benzoquinone, and 2,4,7-trinitro-9-fluorenone (TNF). The rate constants of the quenching of 3ZnPc varied from a diffusion-controlled one to 6×105 dm3 mol−1 s−1 in the mixed solvent of dimethylacetamide (DMA) and water (7:3 by volume). The metal complexes quenched 3MB+ and the triplet state of protonated MB+ with a rate constant of more than 2×106 dm3 mol−1 s−1 in an aqueous solution with 0.5 mol dm−3 of MgCl2. The fractions of electron transfer yielding ZnPc\underset.+ in the quenching process (F1) were high except for TNF and the iron(III) compounds. The F1 fractions were also obtained in the quenching of 3MB+ and the triplet state of the protonated MB+. The absence of radical production in the quenching by the doublet iron(III) compounds can be explained in terms of spin-allowed reverse electron transfer in the life of the geminate radical pair. Fractions of the reverse electron transfer between the half-reduced quencher and ZnPc\underset.+ or MB\underset.2+ were also measured; they are very close to those of 1–F1. The data reported in this study are consistent with the following mechanistic features. (1) Every quenching encounter produces a geminated radical pair. (2) The geminated pair is common to the quenching of the triplet excited state by oxidants and to the reverse electron transfer between the free radicals formed in the quenching. The molar extinction coefficient of ZnPc\underset.+ was determined to be 2.9×104 dm3 mol−1 cm−1 at 520 nm.
Estimation of Compressibility and Volume of Electrostriction Layer in Water–Methanol System and Its Application to the Partial Molar Volumes of LiCl, KCl, and CsCl in This System
Authors: Kawaizumi Fumio , Suzuki Hiroshi , Nomura Hiroyasu , Miyahara Yutaka
Published: July 2006

A theory of electrostriction based on the spherical symmetry of electric field around ion and the dielectric continuum of solvent has been applied to the mixed solvent of water–methanol. The isothermal compressibility, κT, and the volume decrease, ΔV of primary solvation layer have been calculated for univalent ions. Calculation procedure consists of two steps; 1) calculation of the variation of electric field strength and dielectric constant with the distance from ion, 2) calculation of the compressibility and the volume decrease of electrostriction layer. In step 2), the calculation method proposed by Desnoyers et al. (J. Chem. Phys., 43, 243 (1965)) was used. Parameters necessary for the calculation were estimated in an appropriate manner and the results of calculation are shown as plots of κT and ΔV, vs. the distance from the center of ion. Partial molar volumes of LiCl, KCl, and CsCl in water–methanol system have been measured and the disordered part of partial molar volume has been determined after taking account of the values of κT and ΔV of the primary solvation layer.
The Structure of Liquid Water by Neutron Scattering. II. Temperature Dependence of the Liquid Structure
Authors: Ohtomo Norio , Tokiwano Kazuo , Arakawa Kiyoshi
Published: July 2006

The structure factors for heavy water at 25, 50, 70, and 95 °C were determined in the range of Q, 1.4–20 Å−1, by means of the time-of-flight (TOF) neutron diffraction method using the electron linear accelerator (LINAC). An analysis of the neutron diffraction data was made by applying a new general theoretical procedure of analysis for the fluid system composed of molecular clusters with various sizes. Structure factors were calculated according to the general procedure for the pentamer-monomer mixture model as a mixture of regular tetrahedral pentamers and non-bonded monomers with a due assignment of pentamer fraction at each temperature. Excellent agreement was obtained between the calculated and observed structure factors at temperatures in 25–95 °C. Combined with the preceding result (N. Ohtomo, K. Tokiwano, and K. Arakawa, Bull. Chem. Soc. Jpn., 54, 1802 (1981)), it was concluded that the pentamer-monomer mixture model is the best one for water from room temperature to near the boiling point.
Tunnel Electrode I. Electron Transfer Process at Highly Doped SnO2 Electrode with Ce4+ in High Overvoltage Region
Authors: Kobayashi Kenkichiro , Aikawa Yoshihiro , Sukigara Mitsunori
Published: July 2006

Electron transfer theory at tunnel semiconductor electrode was derived from the double adiabatic perturbation theory. The cathodic current of Ce4+ with very positive redox potential was measured at highly doped SnO2 electrode. The rearrangement energy of 0.65 eV for Ce4+ was estimated from the relationship of transfer coefficient vs. electrode potential. Large electron transfer rate in the high overvoltage region can be explained in terms of the contribution of excited vibrational states in the first coordination sphere into electron transfer.
Temperature Effect on the Hydrophobic Hydration in Aqueous Solution of Nonpolar Molecule by Monte Carlo Calculation
Authors: Okazaki Susumu , Touhara Hidekazu , Nakanishi Koichiro , Watanabe Nobuatsu
Published: July 2006

Monte Carlo calculations have been carried out for pure water and aqueous solution of Lennard-Jones particle at infinite dilution between 273.15 K and 353.15 K in order to examine temperature effect on the hydrophobic hydration. It is found that internal energy of mixing ΔU due to the introduction of the solute into water becomes less negative monotonously with increasing temperature. It is in good correspondence with the tendency obtained from solubility measurement, and represents that heat capacity of mixing ΔCV is positive. Furthermore the dissolution proceeds no longer exothermically at 353.15 K, where water behaves as a normal solvent. Several structural and energetical distribution functions have been calculated for the deep understanding of these observations.
Simple Approximate Approaches for the Determination of Circular Dichroism Spectra in Multiple Scattering Systems
Authors: Taniguchi Yutaka , Shimura Yoichi
Published: July 2006

A convenient method for the determination of CD spectra in multiple scattering systems is demonstrated. The formula of approximation, which gives the molar CD in terms of the values observable with commercial spectrometers by using a plate of opal glass, is presented based on some assumptions. The resulting solid-state CD spectrum of Λ-[Co(en)3]Br3·H2O is reported and compared with the solution CD spectrum.
Kinetics and Mechanism of the Oxidation of (Substituted Phenylthio)acetic Acids by Chloramine T
Authors: Srinivasan Chockalingam , Pitchumani Kasi
Published: July 2006

The kinetics of oxidation of (phenylthio)acetic acid and several (para-substituted phenylthio)acetic acids by chloramine T has been studied in alkaline medium (pH 10.06). A first-order dependence in chloramine T and (phenylthio)acetic acid and a near inverse first-order dependence in hydroxide ion has been observed. The oxidation rate considerably decreases with increase of pH. The reaction exhibits positive salt effect and added p-toluenesulfonamide increases the rate. The oxidation process has been shown to proceed via two paths, the major path involving N-chloro-p-toluenesulfonamide as the main oxidizing species and the other involving hypochlorite ion. Studies with (para-substituted phenylthio)acetic acids show an excellent correlation of the rate constants with σ constants. The reaction exhibits a reaction constant ρ of −2.46 at 308 K (r=0.998, s=0.05, confidence limit on ρ±0.15). The activation parameters and isokinetic temperature have been determined.
Diarsenic Trioxide for Substituting Bridging Oxygen for Chlorine in Phosphorus Chlorides
Authors: Watanabe Makoto , Van Wazer John R
Published: July 2006

A preferential exchange of chlorines and bridging oxygens between phosphorus(III and V) chlorides and diarsenic trioxide was studied by adding diarsenic trioxide into phosphorus chlorides and then heating the mixtures at 50–60 °C with vigorous stirring under dried nitrogen (phosphorus(III) chlorides) or dried air (phosphorus(V) chlorides). 31P NMR study showed that the exchange of chlorines and oxygens occurred between diarsenic trioxide and phosphorus trichloride, phosphoryl chloride, diethylphosphinic chloride, tetramethyl-phosphorodiamidic chloride, or diethylphosphinothioic chloride and that P–O–P bonds were formed in the products.
Reactions of Alkanoyl Fluorides with F-Isopropyl and F-1-Chloroethyl Anions
Authors: Ishikawa Nobuo , Iwamoto Kazuhiko , Ishiwata Tatsumi , Kitazume Tomoya
Published: July 2006

Reactions between alkanoyl chlorides and F-propene or F-chloroethene with fluoride ion were investigated. While alkyl (F-isopropyl) ketones and 1-(F-isopropyl)alkenol esters were formed in the former case, 1-(F-1-chloroethyl)alkenol esters were exclusively obtained in the latter case. Reaction mechanisms are discussed.
Alcoholysis Equilibria of Triethylalkoxysilanes Catalyzed by Iodine or Iodine Monobromide
Authors: Ito Katsuko , Ibaraki Takeshi
Published: July 2006

The equilibrium constants K of alcoholysis of triethylalkoxysilanes were determined at 20 °C and 40 °C. Iodine monobromide was used to promote the reactions associated with the tertiary alkoxyl groups, while the other reactions proceeded in the presence of iodine. The K values of the reaction systems with ethoxyl or propoxyl—primary, secondary, and tertiary alkoxyl pairs were 1 or above, about 0.5, and about 0.05, respectively. These values reflect the extent of the binding abilities of the alkoxyl groups to silicon, which is in the expected order of primary>secondary>tertiary alkoxyl groups. A mechanism is postulated for the reaction which involves participation by the iodine or iodine monobromide.
Deoxygenation of Tertiary Amine Oxides with Carbon Bisulfide
Authors: Yoshimura Toshiaki , Asada Kaoru , Oae Shigeru
Published: July 2006

Reduction of various tertiary amine oxides with carbon disulfide was examined and kinetic experiments were carried out. Trialkylamine oxides and N,N-dialkylarylamine N-oxides were readily reduced by CS2 to give the corresponding tertiary amines in good yields, while heteroaromatic amine N-oxides such as picoline N-oxide were not affected. The oxygen atom in the N-oxide was found to be transferred to CO2 upon mass spectral analysis of the gas evolved. The kinetic experiments were carried out following the UV spectra of N,N-dimethylaniline N-oxide in CH3CN containing much excess of CS2 and the rate was found to be of 2nd order in the N-oxide and CS2. Activation parameters (ΔH\eweq=55.7 kJ mol−1, ΔS\eweq=−78.2 J K−1 mol−1 at 20 °C are characteristic of a normal bimolecular reaction. The logarithms of the rate constants for para-substituted N,N-dimethylaniline N-oxides are nicely correlated with Hammett σ values and a small negative ρ value (ρ=−0.2) was obtained. The rate of reaction was faster in polar aprotic solvents than in nonpolar or protic solvents. These observations seem to suggest that the reaction proceeds via an initial nucleophilic attack of the N-oxide oxygen at carbon disulfide followed by the rate-determining N–O bond fission to give the tertiary amine.
Catalytic Efficiency of Functionalized Vesicles in the Transamination of Pyridoxal-5′-phosphate with a Hydrophobic Amino Acid
Authors: Murakami Yukito , Nakano Akio , Akiyoshi Kazunari
Published: July 2006

The transamination reaction of pyridoxal-5′-phosphate (PLP) with N-dodecyl-l-alaninamide (AlaC12) was investigated in an aqueous phosphate–borate buffer at pH 7.0, μ 0.10 (KCl), and 30.0±0.1 °C in the presence of single-walled vesicles of N,N-ditetradecyl-Nα-(6-trimethylamnioniohexanoyl)-l-histidinamide bromide(N+C5His2C14). The electrostatic and hydrophobic interactions between the vesicles and the reactants resulted in incorporation of PLP and AlaC12 into polar and hydrophobic domains of the vesicles, respectively, in the Schiff-base formation process. The isomerization of the aldimine Schiff-base to the corresponding ketimine Schiff-base was confirmed to be the rate-determining step in the transamination process. The reaction site in the vesicular system was found to be equivalent in polarity to dioxane–water (7:3 v/v). However, the overall reaction rate in the vesicles was enhanced 230-fold relative to that in dioxane–water (7:3 v/v). A hydrophobic and suitably polar microenvironment constructed at the reaction site is responsible for such a marked rate-enhancement. In addition, each vesicle of N+C5His2C14 provided functional (imidazolyl) groups in its hydrogen-belt domain to catalyze the intramolecular pro to tropic shift to yield the ketimine Schiff-base. The microenvironmental effects of molecular assemblies of N,N-ditetradecyl-Nα-(6-trimethylammoniohexanoyl)-l-alaninamide bromide and CTAB on the overall transamination were also discussed.