bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Spectroscopic Properties of Germanium Naphthalocyanines
Authors: Iwakabe Yasushi , Numata Shunichi , Kinjo Noriyuki , Kakuta Atsushi
Published: July 2006

Two novel naphthalocyanines, naphthalocyaninatobis(triethylsiloxy)germanium GeNc[OSi(C2H5)3]2 and naphthalocyaninatobis(tributylsiloxy)germanium GeNc[OSi(n-C4H9)3]2 were synthesized. These compounds had a strong absorption peak in the near-infrared; the absorption maximum of their evaporated films shifted to the long-wavelength side from the position in solution.
Thermodynamic Stability of β-Chloro-, β-Phenylthio-, and β-Phenylamino-Substituted α,β and β,γ-Unsaturated Ketones
Authors: Sugita Toshio , Gohda Katsura , Kagiya Tsutomu
Published: July 2006

Acid-catalyzed chemical equilibration studies on the titled compounds have been carried out. The β,γ-isomers are highly favored at equilibrium in the cases of β-chloro- and β-phenylthio-substituted ketones. Hydrogen-bonding between carbonyl oxygen and sulfonium or amine proton stabilizes the α,β-unsaturated form.
Chemical Evolution, Biosynthesis, and Aromaticity
Authors: Aihara Jun-ichi
Published: July 2006

Naturally occurring heterocycles such as imidazole and thiophene do not conform to the rule of topological charge stabilization. Abiotic synthesis and biosynthesis of such heteroconjugated molecules can be rationalized in terms of aromatic stabilization. Antiaromatic molecules are formed neither in primitive-Earth-simulation experiments nor in living systems.
The Intrinsic Equilibrium Constants of the Surface Hydroxyl Groups of Maghemite and Hematite
Authors: Watanabe Haruo , Seto Jun’etsu
Published: July 2006

The intrinsic equilibrium constants of the surface hydroxyl groups, which describe the ionization of surface hydroxyl groups and the complexation of ions of a KCl electrolyte, were calculated with the surface charge densities determined by the potentiometric titration, and with the surface site densities evaluated by the surface hydroxyl group densities. The values of the intrinsic ionization constants, Kalint and Ka2int of maghemite, are higher than those of hematite, and the differences of these values have a tendency for ΔpKalint<ΔpKa2int The values of the intrinsic complexation constants, *KK+int and *KCl-int, of maghemite are higher than those of hematite. These results could be attributed to the differences of the electron densities of the oxygen atoms of the surface hydroxyl groups, which are linked to those in the bulk those of maghemite are lower than those of hematite. Also, the differences become smaller with increasing number of bonding protons.
Mesophase Pitch Derived from Isotropic Anthracene Pitch Produced Catalytically with HF/BF3
Authors: Mochida Isao , Shimizu Kiyoyuki , Korai Yozo , Sakai Yukio , Fujiyama Susumu
Published: July 2006

The thermal preparation of the mesophase pitch from the isotropic anthracene pitch produced catalytically from anthracene with HF/BF3 was studied through both single- and two-stage heat-treatments. The single stage under vacuum provided a mesophase pitch (SMAP-2) of 100% anisotropy and excellent spinnability at yield as high as 59%. The present mesophase pitch maintained the naphthenic structure to some extent, although thermal preparation, which tends to induce dehydrogenative aromatization, was employed. The two-stage preparation, comprising heat-treatments under pressure (2.1 MPa) and then under vacuum (1 Torr, 1 Torr≈ 133.322 Pa) increased the yield of the mesophase pitch to 64%. The resultant mesophase pitch (TMAP) of 100% anisotropy and excellent spinnability carried fewer aliphatic groups than that of the single stage. SMAP-2 was sufficiently stabilized for 30 min at 300 °C, superior to that of the mesophase pitches derived from FCC-DO and the isotropic naphthalene pitch. The complete stabilization of TMAP with a smaller aliphatic structure was achieved within a slightly longer time of 45 min. The number of aliphatic groups is closely related to the stabilization reactivity. It is worth noting that the present mesophase pitches prepared from the isotropic anthracene pitch retained the structure of the starting pitch to an extent which depended on the procedure, influencing the stabilization reactivity.
Stereochemistry in Nucleophilic Vinylic Substitution of Activated Nitro Olefins
Authors: Park Kyong Pae , Ha Hyun-Joon
Published: July 2006

Each of E and Z-isomers of activated α,β-dinitro olefins and α-iodo-β-nitrostilbene reacted ith several different types of nucleophiles such as amines, thiocyanate, and p-toluenethiolate. Only Z-isomers of vinylic-substituted olefins with amines and thiocyanate were observed as products due to the attractive interactions between the nitro group of substrate and the nucleophile in the intermediate state. p-Toluenethiolate as a nucleophile could not interact strongly enough to yield a single Z-product but a converged (E) and (Z) mixture of products. Still, preference is toward Z-configuration.
Nickel-Catalyzed Dehydrogenation of Amines to Nitriles
Authors: Yamazaki Shigekazu , Yamazaki Yasuyuki
Published: July 2006

Aliphatic primary amines having α-methylene underwent oxidative dehydrogenation on treatment with NiSO4 as a catalyst and K2S2O8 as an oxidant to give the corresponding nitriles in good yields. Benzhydrylamine was converted to benzhydrylideneamine quantitatively under the same reaction conditions.
Papain-Catalyzed Hydrolysis of N-Protected Glycosylated Amino Acid Ester
Authors: Ishii Hiroshi , Funabashi Kazuyoshi , Mimura Yoshimasa , Inoue Yoshio
Published: July 2006

The selective hydrolysis of α-methyl ester of glycosylated amino acid derivative, Boc–Asn(NAcGlc)–OMe, was achieved by using papain. Optimal conditions for hydrolysis were estimated.
Molecular Design of Crown Ethers. VII. Syntheses and Cation Selectivities of Unsubstituted 12- to 16-Crown-4
Authors: Liu Yu , Inoue Yoshihisa , Hakushi Tadao
Published: July 2006

Solvent extraction of aqueous alkali and some heavy metal picrates with the title compounds showed that, with most cations except for Li+, Na+, and Ag+, the extractability decreases monotonically as the ring size increases from 12 to 16. However, 14-crown-4 showed the highest extractability and selectivity for Li+ over the larger alkali metals, while 15-crown-4 exhibited the highest Ag+/TI+ selectivity.
Phenylcycloheptabenzofuran from (2-Phenoxyphenyl)phenylcarbene and Its Photoisomerization
Authors: Tomioka Hideo , Murata Hiroshi , Murata Shigeru
Published: July 2006

Photolysis (>350 nm) of (2-phenoxyphenyl)phenyldiazomethane (1)in cyclohexane at 10 °C gave the title compound (4), while similar irradiation with a shorter wavelength light (>300 nm) afforded a mixture of the isomers (5–7), which were shown to be formed by photoisomerization of the initially formed 4.
Acid-Catalyzed Cleavage of Methoxymethyl Phenyl Sulfoxide. Solvent Effects and Mode of Bond Cleavage
Authors: Okuyama Tadashi , Fueno Takayuki
Published: July 2006

Rate constants for the acid-catalyzed hydrolysis of methoxymethyl phenyl sulfoxide increase with increasing composition of dioxane in aqueous dioxane solution in contrast to the isomeric sulfenate which is strongly decelerated by added dioxane fraction (up to 90 vol%). The isotope distribution in the products obtained from the [18O]-sulfoxide was examined in 95 vol% aqueous dioxane. About 90% of the 18O was retained in the product S-phenyl benzenethiosulfinate from the reaction with hydrochloric and hydrobromic acid while only 50–60% of the 18O was found in the thiosulfinate from the reaction with perchloric acid. A plausible reaction mechanism involving ligand coupling within a hypervalent intermediate is proposed for the partial loss of the 18O label in the latter reaction.
ESR Spectra of the Radical Anions of Nitrobenzene and p-Nitrobenzoic Acid Incorporated into Micelles
Authors: Kubozono Yoshihiro , Aoyagi Makoto , Ata Masafumi , Gondo Yasuhiko
Published: July 2006

The radical anions of nitrobenzene and p-nitrobenzoic acid have been prepared chemically for the first time in aqueous solutions with the aid of micelles. The radicals thus prepared are stable and the resulting ESR spectra are unsymmetrical owing to the suppressed rotational diffusion of the radicals due to incorporation into micelles. The environments surrounding the radicals are discussed in terms of the 14N hyperfine coupling constants and the rotational correlation times. For p-nitrobenzoic acid radical anion, the temperature dependence of the ESR spectrum has been studied.
Hindered Internal Rotation Around the C–N Bond in 1H-Azepine Derivatives as Studied by the NMR Techniques
Authors: Itoh Shuji , Yokoyama Yukihiro , Okumoto Takashi , Saito Katsuhiro , Takahashi Kensuke , Satake Kyosuke , Takamuku Hiromi , Kimura Masaru , Morosawa Shiro
Published: July 2006

Thermodynamical parameters for the restricted rotation of seven title derivatives have been obtained by means of DNMR techniques. The results were explained in terms of a conjugation of the nitrogen atom in the seven-membered ring with the adjacent carbonyl carbon.
Elucidation of Shimura’s Reduction Parameter for the First Ligand Field Band Components of Cobalt(III) and Chromium(III) Mixed Ligand Complexes
Authors: Kaizaki Sumio
Published: July 2006

Elucidation was made for Shimura’s recently proposed reduction parameter, which enables us to improve the prediction of the first absorption band components from Yamatera’s rule, in terms of the angular overlap model(AOM) parameterization for cobalt(III) and chromium(III) mixed ligand complexes. From the configuration interaction between the degenerate components and in view of the empirical relation for the eσa and eσb AOM parameters as revealed recently in the nondegenerate component of trans-[Cra4b2] type complexes, Shimura’s empirical reduction parameter α was elucidated semiquantitatively in relation with the difference between the eσ parameter values for the a and b ligands, Δ′σb=3(eσb−eσa); the larger the Δ′σb the smaller the reduction parameter α, and vice versa.
Kinetic Studies on the Reactions of Electrogenerated 9,10-Diphenylanthracene Cation Radical with Water and Alcohols by Means of Column-Electrolytic Stopped-Flow Method
Authors: Oyama Munetaka , Nozaki Koichi , Nagaoka Tsutomu , Okazaki Satoshi
Published: July 2006

The reactions of 9,10-diphenylanthracene cation radical (DPA+·) with water and alcohols in acetonitrile (AN) were studied using a novel column-electrolytic stopped-flow spectrophotometric method. The reaction was first-order with respect to DPA+· in all reactions. The reaction orders of other reactants were determined by plotting the logarithms of the apparent first-order rate constants (kapp’s) against the logarithms of the concentration of reactants. The plot of logkapp vs. log [alcohols] was linear, and hence the reaction was clearly determined to be second-order. On the other hand, the logkapp vs. log [water] plot did not show a linear relationship. Similar results were obtained in the reactions of 9,10-dimethylanthracene cation radical with water and methanol. Comparing the results obtained with water and alcohols, and considering the changes in the physicochemical properties of the AN–water medium, it was concluded that the reaction of water was second-order, though it had been believed previously to be first-order. Products of the reactions are trans- and cis-9,10-dialkoxy-9,10-diphenyl-9,10-dihydroanthracene in many cases.
Photolysis of Triphenylacetic Acid and Its Methyl Ester: A Novel Photochemical Generation of Carbene Intermediates
Authors: Shi Min , Okamoto Yoshiki , Takamuku Setsuo
Published: July 2006

The photolysis of methyl triphenylacetate in methanol gave biphenyl, methyl α-methoxyphenylacetate, methyl benzoate, and methoxydiphenylmethane. The formation of these products suggests that two types of α,α-elimination take place: One is the elimination of two phenyl groups leaving Ph–\"{C}–CO2Me (type a), and the other is the elimination of the phenyl and methoxycarbonyl groups generating Ph2C: (type b). Only type a elimination was efficiently quenched by oxygen.
The Partial Oxidation of Ethane over a B2O3–Al2O3 Catalyst
Authors: Murakami Yasushi , Otsuka Kiyoshi , Wada Yuji , Morikawa Akira
Published: July 2006

The catalytic activities were examined for the partial oxidation of ethane over various metal oxides. B2O3(30wt%)-added Al2O3 showed the highest catalytic activity in the formation of acetaldehyde (yield: 1.03%) and ethylene (14.6%). Ethylene and acetaldehyde are assumed to be formed via a common reaction intermediate because of the similarity in their kinetic behavior and the similar activation-energy values observed. The second-order dependence of the formation rates for the two products on the pressure of ethane suggests that the two molecules of ethane participate in the formation of the intermediate in the chain reaction mechanism proposed. The active site for the formation of acetaldehyde from the intermediate is suggested to be a highly dispersed boron electron-donated from alumina, but that for ethylene must be different from that of acetaldehyde.
Coordination Selectivity in the Reaction of Iron(II) with 8-Hydroxy-7-(8-quinolyl)azo-5-quinolinesulfonic Acid
Authors: Noritake Masaki , Okamoto Ken-ichi , Hidaka Jinsai , Einaga Hisahiko
Published: July 2006

The formation of an iron(II) complex with 8-hydroxy-7-(8-quinolyl)azo-5-quinolinesulfonic acid (QHQS,H2qhqs) has been investigated on the basis of the electronic absorption spectra, the equilibrium, and the stopped-flow kinetics in a 0.10 mol dm−3 aqueous sodium chloride solution at 25°C with a view to elucidating the coordination selectivity of the ligand. A 1:2 (metal:ligand) complex forms in an acidic medium with a selective coordination of QHQS to iron(II), with its 2-(8-quinolylazo)phenol moiety acting as a terdentate ligand. The complex formation reaction proceeds through a single pathway of Fe2+ with Hqhqs−, a ligand species singly protonated at the phenolate oxygen, with the rate constant (k21) of k21=(3.16±0.20)×105 mol−1dm3s−1, to form a mono-ligand complex as the rate-determining step. The coordination of the ligand by 8-quinolyl nitrogen, followed by a rate-determining bonding of phenolato oxygen, was suggested as the reaction mechanism.
Kinetics and Mechanism of Oxidation of Phosphinic, Phenylphosphinic, and Phosphonic Acids by Pyridinium Chlorochromate
Authors: Seth Monila , Mathur Abha , Banerji Kalyan K
Published: July 2006

Oxidation of the lower oxyacids of phosphorus by pyridinium chlorochromate (PCC) results in the formation of the corresponding higher oxyacids of phosphorus. The reaction is of first order with respect to PCC and the oxyacid. The reaction is catalyzed by hydrogen ions, kobs=a+b[H+]. The reaction exhibited a substantial primary kinetic isotope effect. The rates in 19 different organic solvents have been analyzed using Kamlet–Taft’s and Swain’s equations. It has been found that the cation-solvating power of the solvents plays a predominant role. It is proposed that the “inactive” tautomer of the phosphorus oxyacids is the reactive species. Transfer of a hydride ion from the P–H bond to PCC, in the rate-determining step, has been proposed.
Tris(2,2′-ipyridine)ruthenium(II) in Sodium Dodecyl Sulfate-γ-Alumina Hemimicelles. Enhanced Electron Transfer and Exchange Hemimicellization with 1,1′-Dimethyl-4,4′-Bipyridinium
Authors: Sato Hiroyasu , Kasatani Kazuo
Published: July 2006

On addition of 1,1′-dimethyl-4,4′-bipyridinium (methyl viologen, MV2+) to tris(2,2′-bipyridine)ruthenium(II) (R2+) solubilized in sodium dodecyl sulfate (SDS)-γ-alumina hemimicelles (HM), an effective quenching due to electron transfer occurs in HM. Addition of a large amount of MV2+ expels R2+ out of HM into the aqueous phase, as a result of exchange hemimicellization.
Synthesis and Enantiomer Recognition of the 18-Crown-6 Derivative Containing Two Tert-Butyl Substituents as a Chiral Barrier
Authors: Naemura Koichiro , Ueno Michi
Published: July 2006

The optically active 18-crown-6 derivative having two tert-butyl substituents as a chiral barrier was prepared by using (−)-(R)-3,3-dimethylbutane-1,2-diol as a chiral source and its chiral recognition behavior in transport of racemic guest molecules through bulk liquid membranes was investigated.
New Preparative Method of Fine Powder of Yttrium(III) Oxide by Thermal Decomposition of NH4Y(C2O4)2· H2O Fine Crystal Obtained by Reaction of a Strongly Acidic Solution of Yttrium Oxalate and an Aqueous Ammonia Solution
Authors: Minagawa Yukinori , Yajima Fumikazu
Published: July 2006

A fine powder of yttrium(III) oxide has been obtained by calcination of a quasi-stable salt of NH4Y(C2O4)2· H2O, which was prepared by the rapid addition of an aqueous ammonia solution into a strongly acidic yttrium oxalate solution. The particle size distribution weakly depends on the addition time of the aqueous ammonia solution and the agitation speed, and strongly depends on the washing times with pure water and on the calcination temperature of NH4Y(C2O4)2· H2O crystal. The precipitation mechanism of NH4Y(C2O4)2·H2O is discussed in terms of kinetics in the solution.
Formose Reactions. XXVIII. Selective Formation of 2,4-Bis(hydroxymethyl)-3-pentulose in N,N-Dimethylformamide–Water Mixed Solvent
Authors: Shigemasa Yoshihiro , Ueda Takaaki , Saimoto Hiroyuki
Published: July 2006

Dihydroxyacetone, Dl-glycero-tetrulose, and 2,4-bis(hydroxymethyl)-3-pentulose (2,4-BH-3-P) were favorably formed in a formose reaction by choosing a suitable ratio of water to N,N-dimethylformamide used as solvent or a suitable [thiamine·HCl]/[HCHO] ratio. The formose reaction was strongly affected by the concentration of formaldehyde in the water layer. Under the reaction conditions studied, thiamine decomposed rapidly. 2,4-BH-3-P was isolated from the reaction mixture and characterized by MS, IR, and NMR techniques. A pathway for the formation of 2,4-BH-3-P was also proposed.
An Efficient and General Method for the Reformatsky-Type Reaction of Chlorodifluoromethyl Ketones with Carbonyl Compounds Giving α,α-Difluoro-β-hydroxy Ketones
Authors: Kuroboshi Manabu , Ishihara Takashi
Published: July 2006

Chlorodifluoromethyl ketones CF2ClCOR, where R is an alkyl, aryl, and 1-alkynyl group, underwent the Reformatsky-type aldol reaction with a wide variety of aldehydes or ketones in the presence of acid-washed zinc dust and copper(I) chloride or silver acetate to give the corresponding α,α-difluoro-β-hydroxy ketones in good to excellent yields. Specific activation of zinc metal with the metal salt is essential to achieve high efficiency of the reaction, depending upon the structures of the chlorodifluoromethyl ketones and the carbonyl compounds employed. In-situ formed intermediates in these reactions were successfully detected by 19F NMR spectroscopy, which suggests that their structure is not an α-metallo ketone but an oxygen-metallated species possessing the zinc(II) metal as counter cation.
Palladium Catalyzed Direct Oxidation of Benzene with Molecular Oxygen to Phenol
Authors: Jintoku Tetsuro , Takaki Ken , Fujiwara Yuzo , Fuchita Yoshio , Hiraki Katsuma
Published: July 2006

Direct phenol synthesis from benzene is currently one of the most important problems in modern chemistry. We have reported new phenol synthesis from benzene and O2 via direct activation of a C–H aromatic bond by the Pd(OAc)2/phenanthroline catalyst system. The evidence for direct oxidation of benzene by O2 was obtained using 18O and 2H isotopes. The mechanism was proposed on the basis of these results and the reactions of Ph–Pd σ complex intermediates.
The Hydroboration of 1-Alkylthio-l-alkynes, and Its Application to the Syntheses of S-Alkyl Alkanethioates and (Z)-1-Alkylthio-1-alkenes
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira
Published: July 2006

Hydroboration of 1-alkylthio-1-alkynes with dicyclohexylborane or bis(1,2-dimethylpropyl)borane proceeded smoothly, adding most of the dialkylboryl group to the α-position of the triple bond. The resulting alkenylboranes afforded either S-alkyl alkanethioates on a controlled oxidation with alkaline hydrogen peroxide in the presence of N,N,N′,N′-etramethylethylenediamine or (Z)-1-alkylthio-1-alkenes on a basic protonolysis, successive treatments with methyllithium, copper(I) iodide and water in the presence of hexamethylphosphoric triamide.
Oxidation and Reduction Potentials and Electron-Transfer Interactions in Photoexcited States
Authors: Kubota Tanekazu , Uno Bunji , Kano Kenji , Kawakita Toshio , Goto Masashi
Published: July 2006

In this paper we discuss the oxidation and reduction potentials of a solvated redoxcouple in photoexcited states, these being the extension of our foregoing theoretical treatment pertinent to the energetics of sequential electrooxidation (E1⁄2oxd) and reduction (E1⁄2red) steps. After formulating the ionization potential and electron affinity of solvated molecules by using the E1⁄2oxd and E1⁄2red values, the equations on the oxidation (E1⁄2·excoxd) and reduction (E1⁄2·excred) potentials in excited states are derived. From these the important relation (E1⁄2·excoxd+E1⁄2·excred)=(E1⁄2oxd+E1⁄2red) obtained. For the case of a benzenoid alternant hydrocarbon (BAH) the above left-hand-side summation would become constant. Also, the mutual correlation of the E1⁄2·excoxd or E1⁄2·excred value at 1La excited state to the E1⁄2·excred or E1⁄2·excoxd potential at ground state is discussed for BAH’s. Finally the electron-transfer interaction between an electron donor and an electron acceptor has been considered in photoexcited states by virtue of oxidation and reduction potentials. The equation thus obtained is of the same type as that formulated semiempirically by Rehm and Weller. Our treatment provides theoretical background for the Rehm and Weller equation.
Graphite Furnace Atomic Absorption Spectrometric Determination of Bismuth(III) after Coprecipitation with Hafnium Hydroxide
Authors: Ueda Joichi , Takagi Midori
Published: July 2006

A method for the coprecipitation of bismuth(III) with hafnium hydroxide followed by a graphite-furnace atomic absorption spectrometric determination is described. Hafnium hydroxide coprecipitates quantitatively 0.05–3 μg of bismuth(III) from 50–400 cm3 of sample solution at pH 5.8–11.2. The presence of 2.5–50 mg of hafnium in 25 cm3 does not affect the atomic absorbance of bismuth(III). The calibration curve is linear for 0.05–3 μg of bismuth(III) in 25 cm3 and passes through the origin. Interference from the presence of large amounts of silver can be eliminated by removing silver as the ammine complex produced by the coprecipitation procedure at above pH 11 with aqueous ammonia. Several other matrix ions investigated do not interfere with the determination in at least a 500-fold mass ratio to bismuth(III). This method was successfully applied to the determination of trace bismuth(III) in commercial metal silver (purity: 99.99%), and is also applicable to the determination of trace amounts of bismuth(III) in water sample.
Reducibility of Metal Oxides in Hydrogen and Strength of Oxygen Bond in Their Surface Layer
Authors: Klissurski D , Dimitrova R
Published: July 2006

A distinct correlation between the reducibility of metal oxides in hydrogen and the strength of the oxygen bond in their surface layer has been found. Simultaneously it has been shown that the widely accepted concept for a correlation between the melting points of oxides and their reducibility needs a critical reconsideration.
Cooperation of Imidazolyl and Carboxylate Residues for Efficient Cleavage of Bis(nitrophenyl) Hydrogenphosphates
Authors: Komiyama Makoto
Published: July 2006

4-Imidazoleacetate efficiently catalyzes the cleavage of bis(2,4-dinitrophenyl) hydrogenphosphate and bis(4-nitrophenyl) hydrogenphosphate (1600 and 15000 fold acceleration at pH 8.0 at 1.0 mol dm−3). The effective catalysis is ascribed to the intramolecular cooperation of the imidazolyl and the carboxylate residues.
The Role of Triplet State of Nitrospiropyran in Their Photochromic Reaction
Authors: Sakuragi Masako , Aoki Kousou , Tamaki Takashi , Ichimura Kunihiro
Published: July 2006

The effects of intermolecular and intramolecular triplet quenchers and sensitizers on the photochromism of nitrospiropyran have been examined in order to clarify the role of the triplet state (3A*) as well as that of the excited singlet state (1A*). The rates of photocoloration and fatigue were significantly affected: the quenchers retarded both rates, while the sensitizers retarded the former but enhanced the latter rate. It can be concluded that more than 90% of the total amount of photomerocyanin is generated from 1A* in the photostationary state and that fatigue proceeds mainly through 3A*.
Circuit Resonance Energy. On the Roots of Circuit Characteristic Polynomial
Authors: Mizoguchi Noriyuki
Published: July 2006

The circuit characteristic polynomial plays an important role in the theory of circuit resonance energy of polycyclic conjugated molecules. Although in the use of circuit resonance energy it is essential that the circuit characteristic polynomial has real roots, the definition of circuit characteristic polynomial does not ensure that the roots of this polynomial are real numbers. It is proved that the circuit characteristic polynomial for any circuit in a polycyclic conjugated molecule has no imaginary roots if this molecule is a nonfused polycyclic conjugated molecule or a fused bicyclic system.
The Determination of a Small Amount of a Biological Constituent by Use of Chemiluminescence. XVI. High-Sensitive Detection of Proteins by an Ion–Exchange Chromatograph–Chemiluminescence Detector System
Authors: Hara Tadashi , Tsukagoshi Kazuhiko , Tsuji Haruyuki
Published: July 2006

An ion-exchange chromatograph–chemiluminescence detector system was developed by connecting a high-resolution ion-exchange column with a chemiluminescence detector using a 1,10-phenanthroline–hydrogen peroxide–copper(II) system which was first developed by the authors for the detection of protein. A sodium tetraborate–hydrochloric acid buffer solution was found to be suitable for the development of well-defined chromatogram without lowering the resolution of an ion-exchange column and the sensitivity of a chemiluminescence detector. The elution of protein was carried out by a gradient elution method. According to the present method, two mixture samples of ovalbumin–trypsin inhibitor (from soybean, crude) or bovine serum albumin–trypsin inhibitor (from soybean, crude)–trypsin inhibitor (from chicken egg white), which were too dilute to detect by a UV detector, gave chromatograms similar as in UV detection.
Direct Phosphonation of Naphthalene and Phenanthrene with Trialkyl Phosphites via Photochemical Electron Transfer
Authors: Yasuda Masahide , Yamashita Toshiaki , Shima Kensuke
Published: July 2006

Direct photophosphonations of naphthalene and phenanthrene with trialkyl phosphites occurred in the presence of electron acceptors to give arylphosphonates and dihydroarylphosphonates.
The Synthesis of Benzofuroquinolines. VI. A New Synthesis of Benzofuro[2,3-c]quinoline Derivatives
Authors: Yamaguchi Seiji , Oh-hira Yutaka , Yamada Minoru , Michitani Hitomi , Kawase Yoshiyuki
Published: July 2006

Two benzofuro[2,3-c]quinoline derivatives, 6-methylbenzofuro[2,3-c]quinoline and 6(5H)-benzofuro[2,3-c]quinolinone, were synthesized by the condensation of 2-amino-2′-hydroxybenzophenone with chloroacetone, ethyl bromoacetate, or chloroacetonitrile. The benzofuroquinolinone, thus obtained, was converted to 6-chloro and 6-cyanobenzofuro[2,3-c]quinolines.
Photoinduced Organic Transformation. Selective Synthesis of Ethylene Glycol or Formic Acid and Methyl Formate from Methanol in the Presence of Hydrogen Peroxide
Authors: Shimizu Yuichi , Sugimoto Shun’ichi , Kawanishi Shunichi , Suzuki Nobutake
Published: July 2006

The photoinduced transformation of methanol (MeOH) has been investigated in the presence of H2O2. Ethylene glycol (EG) was selectively produced by UV light irradiation of the N2-saturated MeOH and the selectivity was 85–94% below 3 ml h−1 of H2O2 feeding rate (f). The quantity of EG reached the maximum at f=5 ml h−1 and the quantum yield was 0.73. EG was produced through the dimerization of hydroxymethyl radicals formed by the abstraction of hydrogen atom from MeOH by hydroxyl radical which was formed by the photolysis of H2O2. On the other hand, formic acid (FA) and methyl formate (MF) were selectively produced by UV light irradiation of the O2-bubbled MeOH and the combined selectivity was about 99% in the f range of 1–8 ml h−1. The quantities of FA and MF reached the maximum at f=5 ml h−1 and their quantum yields were 1.36 and 0.69, respectively. FA was mainly produced through the decomposition of hydroperoxyhydroxymethane formed by the abstraction of hydrogen atom from MeOH by hydroxymethyldioxy radical which was formed by the reaction of hydroxymethyl radical with oxygen, and MF through the reaction of MeOH with FA formed.
The Amino–Imino Tautomerization of the 2-Aminopyridine–Acetic Acid System in Isooctane
Authors: Inuzuka Kozo , Fujimoto Akira
Published: July 2006

The UV absorption spectra of 2-aminopyridine were measured in isooctane (2,2,4-trimethylpentane) containing various amounts of acetic acid at room temperature; the temperature dependence (20–−80°C), of the spectra was also determined, while the concentration of acetic acid was maintained constant. An additional shoulder band appeared around 335 nm in the spectra obtained when the acetic acid concentration was higher than 1×10−2 mol dm−3. The band corresponding to the 335 nm band was observed for monomethyl-substituted 2-aminopyridine. The 335 nm band was assigned to the π–π* transition of the (E)-2(1H)-pyridinimine moiety in the 2-aminopyridine-acetic acid complex. The proton transfer from acetic acid to 2-aminopyridine in the complex may be difficult energetically in the ground state.
The Preparation of Alkyltrimethylammonium–Kanemite Complexes and Their Conversion to Microporous Materials
Authors: Yanagisawa Tsuneo , Shimizu Toshio , Kuroda Kazuyuki , Kato Chuzo
Published: July 2006

Single layered polysilicate kanemite (NaHSi2O5·3H2O) was allowed to react with alkyltrimethylammonium chloride solutions to form alkyltrimethylammonium–kanemite complexes. During the organic intercalation, the SiO2 layers in the complexes were condensed to form three-dimensional SiO2 networks. The calcined products of the complexes had micro pores 2–4 nm in diameter, and the surface areas were ca. 900 m2g−1. The pore size of the calcined products was altered with the variation in the alkyl-chain length of the alkyltrimethylammonium ions employed.
Translational Energy Distributions and Emission Cross Sections of the Excited Hydrogen Atom Produced in e–SiH4 Collisions
Authors: Tsuboi Toshiyuki , Nakashima Keiji , Ogawa Teiichiro
Published: July 2006

The translational energy distributions of H* (n=3, 4) produced in e–SiH4 collisions were obtained by measuring the Doppler profiles of the Balmer-α and β lines with a Fabry–Perot interferometer. There are three major components in the translational energy distributions of H* (n=3, 4). The first component lies in the 0–3 eV region, the second one peaks at 2–3 eV, and the third one lies at above 4 eV. Thus, dissociation of SiH4 for the formation of H* (n=3, 4) should proceed through three different groups of Rydberg states. The emission cross sections were determined separately for H* (n=3, 4) with the translational energy of 0–2, 2–4, 4–6, 6–8, and 8–10 eV, respectively.
Catalytic Isomerization of Trimethylbenzenes over a Graphite–Sulfuric Acid
Authors: Tsuchiya Susumu , Fujii Kenji , Mitsuno Tadashi , Sakata Yoshihisa , Imamura Hayao
Published: July 2006

The isomerization of 1,2,3- and 1,2,4-trimethylbenzene took place over a graphite–sulfuric acid to form 1,2,4- and 1,2,3-trimethylbenzene, respectively, but that of 1,3,5-trimethylbenzene was not observed.
Infrared Spectra of SiO2 Coating Films Prepared from Various Aged Silica Hydrosols
Authors: Muroya Masaaki
Published: July 2006

Measurements have been made of the vibrational absorption bands of silica films. The results have been used to examine the importance of the polymerization of silica. Seven other absorption bands, which are related to the Si–O group, were clearly found in the region from 1300 to 400 cm−1. A band at a wave number of 1069 cm−1 increased with increasing the viscosity of the hydrosol. The band at 974 cm−1 was substantially sensitive in intensity to the heat-treatment and the rehydration of silica film, can be assigned to the Si–O stretching vibration of the surface silanol since the intensity of its band is influenced by both the heat-treatment(dehydration) and rehydration.
New Curvularin-Type Metabolites from the Hybrid Strain ME 0005 Derived from Penicillium Citreo-viride B. IFO 4692 and 6200
Authors: Lai Sheng , Shizuri Yoshikazu , Yamamura Shosuke , Kawai Kazuaki , Furukawa Hideyuki
Published: July 2006

Four new curvularin-type metabolites (11-α-methoxycurvularin, 11-β-methoxy curvularin, 11,12-dihydroxycurvularin, and 12-hydroxy-10, 11-trans-dehydrocurvularin) have been isolated from the mycelium of the hybrid strain ME 0005 derived from Penicillium citreo-viride B. IFO 4692 and 6200. And β-hydroxycurvularin, the biologically active principle from Alternaria tomato, was identified as 11-β-hydroxycurvularin.
Polypeptide Synthesis Using the S-Alkyl Thioester of a Partially Protected Peptide Segment. Synthesis of the DNA-Binding Domain of c-Myb Protein (142–193)–NH2
Authors: Hojo Hironobu , Aimoto Saburo
Published: July 2006

A method for polypeptide synthesis using S-alkyl thioester of a partially protected peptide segment has been developed. The DNA-binding domain of c-Myb protein (142–193) was synthesized by this method to estimate its usefulness. The partially protected peptide segments, Boc–[Lys(Boc)143,144,160]–c-Myb protein(142–163)–SCH2CH2CONH2 and [Lys(Boc)171,182,192]–c-Myb protein(164–193)–NH2, were highly purified from peptides obtained by a solid-phase method. The thioester in the carboxyl component of the peptide segment was converted to the corresponding p-nitrophenyl ester in the presence of silver ions and p-nitrophenol and then the two segments were condensed. The coupling reaction proceeded almost completely yielding a highly-purified product after removal of Boc groups.
Conformation in Solution of the Fully Toxic Domain of Heat-Stable Enterotoxin (STp) Produced by Enterotoxigenic Escherichia coli
Authors: Ozaki Hiroshi , Kubota Hirokazu , Sato Takashi , Hidaka Yuji , Tamaoki Haruhiko , Kobayashi Yuji , Kyogoku Yoshimasa , Sugimura Takashi , Tai Akira , Shimonishi Yasutsugu
Published: July 2006

Heat-stable enterotoxin (STp) produced by a porcine strain of enterotoxigenic Escherichia coli is a peptide of 18 amino acid residues. The full toxicity is generated by a core peptide of 13 amino acids from residue 5 to 17 (STp(5–17)). Detailed conformational analysis of STp(5–17) was performed by NMR spectroscopy and distance geometry calculations. The tertiary structure of STp(5–17) was found to have a right-handed spiral fold throughout the whole molecule which was stabilized by the network of disulfide linkages and hydrogen bonds. This folding pattern was demonstrated in both organic and aqueous solutions.
Small-Angle X-Ray Scattering Study of Cytochrome Oxidase from Beef Heart and Its Complex with Cytochrome c Using Contrast Variation Method
Authors: Morimoto Yukio , Sato Mamoru , Kato Tatsuhisa , Tanaka Nobuo , Katsube Yukiteru , Tanaka Masashi , Ozawa Takayuki
Published: July 2006

The structure of cytochrome oxidase from beef heart and its complex with cytochrome c were investigated in solution by X-ray small-angle scattering. The contrast variation method was applied to the present analysis. The radii of gyration and maximum dimensions were estimated to be 54 and 165 Å for the cytochrome oxidase and 56 and 165 Å for the complex, respectively. A model of the dimer was constructed so as to interpret the X-ray scattering data well. It was concluded that cytochrome c is bound to the hydrophilic surface of the enzyme near the edges of the ellipsoidal molecule, and that detergent molecules exist on the surface of the central parts of the enzyme.
An Ab Initio Molecular Orbital Study on Twisting in Silyl-Substituted Ethylene Cation Radicals
Authors: Takahashi Ohgi , Morihashi Kenji , Kikuchi Osamu
Published: July 2006

Twisting in two silyl-substituted ethylene cation radicals, the cation radicals of vinylsilane (1) and vinylidenebissilane (2), were investigated by ab initio UHF calculations with the 3-21G and 3-21G(*) basis sets. Both 1+· and 2+· were found to have twisted equilibrium structures, the twist angle being 29° and 42°, respectively. The planarization barriers evaluated for 1+· and 2+· are about 1 and 7 kcal mol−1, respectively. The planar and 90°-twisted forms of 2+· have comparable energies. The hyperconjugation of the C-Si bonds is reflected in the calculated molecular structures.
Product Selectivity Affected by Cationic Species in Electrochemical Reduction of CO2 and CO at a Cu Electrode
Authors: Murata Akira , Hori Yoshio
Published: July 2006

Electroreduction of CO2 and CO was studied with a copper electrode in hydrogencarbonate solutions of various cations. Product selectivity was greatly affected by cationic species as well as HCO3− concentration. H2 evolution prevailed over CO2 reduction in Li+ electrolyte, whereas CO2 reduction was favorable in Na+, K+, and Cs+ solutions. C2H4 formation became greater than CH4 with increase of the cation size, i.e. with sequence of Li+, Na+, K+, Cs+. The variation of the product selectivity caused by cationic species is rationalized by the difference of outer Helmholtz plane (OHP) potential. The OHP potential will vary with cationic species in accordance with the degree of specific adsorption. The concentration of H+ at the electrode will depend upon the OHP potential, since H+ is a charged species. This difference of pH at the electrode will lead to the variation of product selectivity.
Effect of Ether Oxygen on Proton Transfer and Aggregation Reactions of Amines in Water by Ultrasonic Absorption Method
Authors: Nishikawa Sadakatsu , Haraguchi Hiroshi , Fukuyama Yasuyo
Published: July 2006

Ultrasonic absorption coefficients in the frequency range from 6.5 to 220 MHz have been measured in aqueous solutions of 3-ethoxy- and 3-butoxypropylamine as functions of their concentrations along with the sound velocity at 2.5 MHz and the density. In a 3-ethoxypropylamine solution, only one relaxational absorption has been observed up to 3.0 mol dm−3. The cause has been clarified to be due to a proton-transfer reaction of the amine from the concentration dependences of the relaxation frequency and the relaxational amplitude. The rate and thermodynamic parameters have been determined and reasonable values have been obtained as a diffusion-controlled reaction. In the solution of 3-butoxypropylamine, another relaxation process in addition to that due to the proton-transfer reaction has been observed in the concentrations of more than 0.5 mol dm−3. This relaxation process has been attributed to a perturbation associated with an aggregation reaction, 4A↔A4, from the concentration dependences of the relaxation frequency and the relaxational amplitude of the absorption. The rate and thermodynamic constants for the proton-transfer and aggregation reactions have been determined. It has been found from a comparison of the results for the two solutions and others reported previously that the introduction of ether oxygen into amine molecules has little influence on the proton-transfer reaction, but prevents the formation of aggregates due to the hydrophobic interaction. It has also been seen from the results of 3-butoxypropylamine solutions that the butoxyl group has a fairly high ability of hydrophobic interaction and that nonionized molecules form aggregates in the aqueous solution.
Broadening of the Proton Magnetic Resonance Spectra of Sulfonate Anions by Ion Pairing with Paramagnetic Chromium(III) Complexes
Authors: Iida Masayasu , Yokoyama Haruhiko
Published: July 2006

The paramagnetic line broadening of both the 1H spectra of CH3SO3− and (CH2SO3)22− was observed in aqueous solutions including chromium(III) complexes such as [Cr(en)3]3+ (en=ethylenediamine), [Cr(phen)3]3+(phen=1,10-phenanthroline), and lel,lel,lel-[Cr(chxn)3]3+ (chxn=trans-1,2-cyclohexanediamine). The dependence of the line broadening on the concentration of chromium(III) complexes was attributed to contact ion-pair formation. The distances between the Cr atom and the H atoms of the anions in contact ion pairs were derived in order to discuss their configurations. The anions were considered to be in contact with the complex ions through one or two sulfonate groups directed toward the Cr atom in the open space along the C3-axis of the complex or in hollow regions between the ligands.
Formation of Acrylaldehyde by Vapor-Phase Aldol Condensation I. Basic Oxide Catalysts
Authors: Ai Mamoru
Published: July 2006

Vapor-phase aldol condensation of formaldehyde with acetaldehyde to form acrylaldehyde was studied with various oxides supported on silica gel using 35% formalin as the source of formaldehyde. The silica gel unsupported catalyst prepared from colloidal silica showed a relatively high activity and selectivity to form acrylaldehyde. The catalytic activity was markedly enhanced by the incorporation of a basic or amphoteric oxide into the silica gel, while it fell with the incorporation of an acidic oxide such as P2O5 or B2O3. The highest yields of acrylaldehyde were obtained with the Si–Mg, Si–Li, Si–Na, and Si–Zn oxide systems. Effects of reaction variables were also studied using a catalyst with an Si : Mg atomic ratio of 100 : 10.
Crystal Structure of 2′-O-Succinyladenosine 3′,5′-(Cyclic)phosphate Monohydrate: A Model Compound to Study Protein–Nucleic Acid Interactions
Authors: Padmaja Natarajan , Ramakumar Suryanarayana Rao , Viswamitra Mysore A
Published: July 2006

The crystal and molecular structure of 2′-O-succinyladenosine 3′,5′-(cyclic)phosphate monohydrate has been determined by X-ray diffraction techniques. The compound crystallizes in the orthorhombic space group P212121; Z=4 with a=5.633(1), b=15.853(2), c=20.607(3) Å. The final R value is 0.029. The adenine base is protonated at N(1). The base is in syn conformation (χ=−95.8°) with respect to the sugar, which has a C(3′)-endo-C(4′)-exo pucker (4T3). A six-membered ring formed by phosphate group and ribose shows chair conformation. The succinic acid moiety, which resembles side chains of certain amino acids, is found to have a bent skeleton. The cyclic AMP, which is known to play diverse roles in many metabolic processes, forms the nucleotide portion of the title compound. The succinic acid moiety that is covalently linked to this nucleotide in the present compound, shows direct and water mediated interactions with phosphate and base nitrogens of the nucleotide respectively. Such compounds can therefore serve as models to study the protein–nucleic acid interactions, which play a central role in many of the biological processes.
Palladium-Catalyzed Synthesis of N-Benzoyl-2-arylethenesulfonamides from [2-(Benzoylsulfamoyl)ethyl]pyridinium Chloride and Aryl Halides
Authors: Hirooka Syuzi , Tanbo Yuzi , Takemura Katsuya , Nakahashi Hironori , Matsuoka Tsuyoshi , Kuroda Shigeyasu
Published: July 2006

A new, general synthesis of N-benzoyl-2-arylethenesulfonamides by the reaction of aryl halides including heteroaryl halides with [2-(benzoylsulfamoyl)ethyl]pyridinium chloride in the presence of palladium acetate is described.
Comments on the “Synthesis and Characterization of Some New Organophosphonates and Their Adducts with Some Metals” by Saad and Ramadan
Authors: Breuer Eli , Goldblum Amiram
Published: July 2006

This NOTE criticized experimental work, calculations and the conclusions based on them, in a paper recently publishied.
Spin-Trapping Studies on the Reaction of Iron Complexes with Peroxides and the Effects of Water-Soluble Antioxidants
Authors: Kohno Masahiro , Yamada Masako , Mitsuta Keiichi , Mizuta Yokio , Yoshikawa Toshikazu
Published: July 2006

Using ESR spin-trapping techniques we measured the levels of free radical species generated from six different systems (hypoxanthine-xanthine oxidase, iron(II)–hydrogen peroxide, iron(III)–hydrogen peroxide, iron(II)–t-butyl hydroperoxide, iron(III)–t-butyl hydroperoxide, and catalase (CAT)–t-butyl hydroperoxide). Six types of radicals (O2−·,·OH, ·H, ·CH3, (CH3)3CO·, and (CH3)3COO·) were detected as spin adducts of spin traps 5,5-dimethylpyrroline 1-oxide (DMPO) or 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS). Quantitative analysis of the levels of generated radicals by means of an ESR instrument also presents important information regarding the reduction of peroxides [hydrogen peroxide (H2O2) or t-butyl hydroperoxide (ROOH)] by iron(II) or iron(III) as well as catalase. In addition, the scavenging potencies of different water-soluble antioxidants such as l-ascorbic, d-isoascorbic, gallic, sorbic, and protocatechuic acids were evaluated in terms of their ability to reduce the peaks of spin adducts.
On the Facilitation Effect of Neutral Macrocyclic Ligands on the Ion Transfer across the Interface between Aqueous and Organic Solutions. I. Theoretical Equation of Ion-Transfer-Polarographic Current-Potential Curves and Its Experimental Verification
Authors: Matsuda Hiroaki , Yamada Yutaka , Kanamori Kazuo , Kudo Yoshihiro , Takeda Yasuyuki
Published: July 2006

A theoretical equation of the reversible polarographic current-potential curves for the ion transfer across the aqueous/organic interface facilitated by the neutral macrocyclic ligand present in the o-phase is derived without any limitation on the magnitude of distribution constant of the ligand. In two limiting cases, which have been employed in common experimental practice, i.e., (A) the bulk concentration of cation, c*M, in the aqueous phase >> that of ligand, c*L, in the organic phase and (B) the reverse condition, c*M<<c*L, the equation of current-potential curves becomes the same in form as that of reversible D. C. polarographic waves. It is shown that the limiting current is controlled by diffusion of ligand in the organic phase for (A) and of cation in the aqueous phase for (B) and, on the other hand, the half-wave potential depends on c*M for (A) and on c*L for (B). Furthermore, an analysis method to determine the complex formation constants in the organic phase (and in the aqueous phase for favorable cases) from the concentration dependence of the half-wave potential is presented. The theoretical predictions are verified experimentally using dibenzo-18-crown-6 and 18-crown-6 as macrocyclic ligands and sodium, cesium, barium, and oxonium ions as transferred cations.
Studies on the Secondary Structure of Bradykinin in Aqueous Solution. Syntheses, Circular Dichroism Spectra, and Biological Activities of Bradykinin Analogs Containing 5-Aminovaleric Acid Residue
Authors: Hashimoto Chikao , Tamaki Makoto , Sofuku Shosuke , Muramatsu Ichiro
Published: July 2006

Eight bradykinin analogs containing 5-aminovaleric acid residue were synthesized by a solution method. Based on the consideration concerning their CD spectra, the presence of an intramolecular 3→1 hydrogen bond between the carbonyl oxygen of Ser6 and the amide proton of Phe8, an intramolecular 4→1 hydrogen bond between the carbonyl oxygen of Pro2 and the amide proton of Phe5, and a salt bridge between the guanidino group of Arg1 and the carboxyl group of Arg9, was proposed for the secondary structure of bradykinin in aqueous solution. The biological activities of these analogs depend on the presence of both Phe residues at positions 5 and 8, and Arg residues at positions 1 and 9. No correlation between the biological activities and the secondary structure could be found.