bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Chamigrane-type Bromo Diether from the Red Alga Laurencia nipponica Yamada
Authors: Kikuchi Hajime , Suzuki Teruaki , Suzuki Minoru , Kurosawa Etsuro
Published: July 2006

A new halogenated sesquiterpene diether has been isolated from the title alga and its structure was established on the basis of the spectral and chemical evidence.
Irreversible Conformational Change of the Complex of Poly(l-lysine) with Methyl Orange upon Irradiation of Light
Authors: Yamamoto Hiroyuki
Published: July 2006

The effect of light on the chiral complex of poly(l-lysine) (PLL) with Methyl Orange (MO) was studied by means of absorption and circular dichroism (CD) measurements. Upon irradiation, the magnitude of the induced CD of the PLL–MO complex decreased together with a decrease in dimeric dye species. The change was irreversible under dark or visible-light conditions.
A Facile Synthesis of 2-Acyl-3-amino-5-phenacylthio-4-phenylthiophenes from Sodium Cyanophenyldithioacetate and α-Halo Ketones
Authors: Fuchigami Toshio , Kandeel Zaghloul El-Shahat , Nonaka Tsutomu
Published: July 2006

Various kinds of α-halo ketones readily reacted with sodium cyanophenyldithioacetate to provide 2-acyl-3-amino-5-phenacylthio-4-phenylthiophenes in good yields.
The Reaction of Cyclopropenethione with Carbonyl-stabilized Phosphonium Methylides to Yield 2H-Pyran-2-thione
Authors: Yoshida Hiroshi , Shimizu Jyun , Ogata Tsuyoshi , Matsumoto Kiyoshi
Published: July 2006

The reaction of diphenylcyclopropenethione with carbonyl-stabilized triphenylphosphonium methylides (2) to yield 2H-pyran-2-thiones was studied. It was clarified that electron-releasing substituents increased the reactivity of 2.
Rapid Spectrophotometric Determination of Chromium(III) with 1-(2-Thiazolylazo)-2-naphthol in Presence of Surfactant
Authors: Rathaiah Gogineni V , Eshwar Muppalla C
Published: July 2006

Chromium(III) reacts with 1-(2-thiazolylazo)-2-naphthol at 80–95°C in acid media (pH 5.7), in presence of benzoate and sodium dodecyl sulfate. Presence of surfactant increases sensitivity of the complex and reduces heating time to 5 min, thus giving rise to perhaps the most rapid method for absorptiometric determination of chromium(III). The 1:1 complex obeys Beer’s law for 0.2 to 2.4 μg of Cr(III) per ml, has molar absorptivity and Sandell sensitivity of 1.46×104 dm3mol−1cm−1 and 3.5 ng cm−2 respectively, at 575 nm.
Synthesis of New Heterocycles: Condensation of 2-Methyl-4H-naphth[1,2-d][1,3]oxazin-4-one with Schiff Bases and Formation of 3-Aryl-2-styrylbenzo[h]quinazolin-4(3H)-ones
Authors: Reddy Mandala Satyanarayana , Ratnam Chengalvala Venkata
Published: July 2006

Condensation of 2-Methyl-4H-naphth[1,2-d][1,3]oxazin-4-one (2) with Schiff bases (3) in acetic acid has resulted in 3-aryl-2-styrylbenzo[h]quinazolin-4(3H)-ones (4), characterized by spectral and analytical methods.
Studies on the Hydrous Niobium(V) Oxide Ion Exchanger. I. A Method for Synthesis and Some Properties
Authors: Inoue Yasushi , Yamazaki Hiromichi , Kimura Yasuyuki
Published: July 2006

A comprehensive study of the preparation of hydrous niobium(V) oxide ion exchangers was made using three kinds of niobium solutions: (1) HCl, (2) C2H5OH, and (3) H2SO4. From a detailed examination of the dependency of the yield, the ion-exchange behavior toward Na+, the chemical stability, and some other properties, regarding the method for precipitation, it was found that the pyrohydrolysis of the NbCl5 solution was the best method, since the procedure was simple, rapid and reproducible, and the product had a comparatively good ion-exchange property. The product obtained from the H2SO4 solution had the largest ion-exchange capacity and was most stable in highly alkaline solutions, but the whole procedure was very tedious. The exchanger prepared from the ethanolic solution had a smaller ion-exchange capacity in a pH region higher than 8. The materials, thus obtained, had at least two kinds of weakly dissociable ion-exchange sites, and the ion-exchange capacity for alkali metal ions decreased in the order of Li+>Na+>K+. The aging effect and the chemical stability were also examined.
Functionalized Dithia(2,5)pyridinophanes as Vitamin B6 Analogues. Synthesis, Properties, and Catalytic Activity for Racemization Reaction
Authors: Iwata Masaaki , Kuzuhara Hiroyoshi
Published: July 2006

Exploration of synthetic routes to achieve designed vitamin B6 models on the structural basis of functionalized dithia(2,5)pyridinophanes from pyridoxine hydrochloride was undertaken and the catalyst potency for a racemization reaction was examined in comparison with that of pyridoxal. By the reaction of 3,4′-O-isopropylidenepyridoxine 2′,5′-dichloride with α,ω-dithiols, dithia(2,5)pyridinophanes were synthesized in good yields. For dithia[3]paracyclo[3](2,5)pyridinophanes, juncture sulfur atoms were extruded photochemically, whereas 2,(n+3)-dithia[m](2,5)pyridinophanes incompletely extruded sulfur atoms under various conditions. Because of instability and low preparative yield of 15-hydroxy-16-formyl[2]paracyclo[2](2,5)pyridinophane, dithia-containing phanes, (n+9)-hydroxy-(n+10)-formyl-2,(n+3)-dithia[m](2,5)pyridinophanes [26a (n=4), 26b (n=6), 26c (n=8); m=n+4], 17-hydroxy-18-formyl-2,11-dithia[3]paracyclo[3](2,5)pyridinophane (27), and an acyclic congener for 26a, 5′-deoxy-2′,5′-bis(ethylthio)pyridoxal (28), were eventually prepared in high yields by use of manganese dioxide in the presence of a primary amine. It was found on the basis of 1H-NMR spectral analyses that the rotations of pyridine rings in some molecules, 26a, 26b, and 27 with ring sizes equal to or less than fourteen were restricted. The racemization potency of 26a–c, 27, and 28 for sodium hydrogen l-glutamate demonstrated that these are 1.4- to 1.7-fold more potent than pyridoxal itself under certain conditions (pH 10.0, 25±0.5 °C) until ca. 80% completion of the racemization reaction. 26a was found to be quite stable (no decomposition), but the others, 26b, 26c, and 28, indicated 14, 8, and 12% decomposition, respectively. 27 was so unstable that a 63% decomposition was marked at the time of 56% completion of the racemization reacion.
ENDOR Studies of Vitamin E Model Radical. The Solution Structure and Dynamic Behavior of Chromanyloxyl Ring
Authors: Mukai Kazuo , Takamatsu Kimiko , Ishizu Kazuhiko
Published: July 2006

ENDOR technique has been used to elucidate the solution structure and dynamic behavior of chromanyloxyl ring in vitamin E radical. We have measured the ENDOR spectrum of a stable vitamin E model radical (7-t-butyl-2,2,5-trimethyl-6-chromanyloxyl (1)) in toluene in the temperature range −30°–−100°C. From detailed analysis of the temperature dependence of hyperfine coupling of β-methylene protons in the heterocyclic ring, the equilibrium conformation of the β-methylene group and activation energy, enthalpy and entropy for the conformational interconversion of the heterocyclic ring have been determined. The observed positive temperature dependence of the hyperfine coupling constants (a5CH3 and a8H) may be explained as a consequence of the restricted motion about the C8a–O1 bond in the chromanyloxyl ring, based on the McLachlan MO calculation.
The Conformers of 2,2′-Bipyridine in the Phosphorescent Triplet State as Studied by Electron Spin Resonance and Phosphorescence
Authors: Yagi Mikio , Makiguchi Kazuhiro , Ohnuki Atsushi , Suzuki Kazuhiro , Higuchi Jiro , Nagase Shigeru
Published: July 2006

Two sets of triplet-state ESR spectra corresponding to the s-cis and s-trans conformers of 2,2′-bipyridine have been observed in mixtures of water with various alcohols at 77K. The intensity ratio of the ESR signal for the s-cis conformer to that for the s-trans conformer depends on the composition of the mixture and on the sample-cooling rate. From the analysis of the phosphorescence spectra, the lowest triplet state of the s-cis conformer is estimated to be close to that of the s-trans conformer. An anomalous ESR signal which cannot be ascribed to either the s-cis conformer or the s-trans conformer has been observed in a 1-propanol-water mixture. The geometries of these conformers are discussed from their observed zero-field splitting parameters, together with their potential energy diagrams, as obtained by an ab initio calculation.
Ring-cleavage Reactions of Aromatic Hydrocarbons Studied by FT–IR Spectroscopy. II. Photooxidation of o-, m-, and p-Xylenes in the NOx–Air System
Authors: Bandow Hiroshi , Washida Nobuaki
Published: July 2006

α-Dicarbonyl compounds produced in the photooxidation of o-, m-, and p-xylenes were analyzed quantitatively using long-path FT–IR spectroscopy. Glyoxal, methylglyoxal, and biacetyl were observed in the case of o-xylene, and glyoxal and methylglyoxal were observed in cases of m- and p-xylenes. Yields of glyoxal, methylglyoxal, and biacetyl were 8, 23, and 10% (mole/mole) of o-xylene consumed, respectively. Yields of glyoxal and methylglyoxal were 13 and 42% in the case of m-xylene, and 24 and 12% in the case of p-xylene. These yields could be explained by the ring cleavage of 6,7-dioxabicyclo[3.2.1]octane compounds of OH–aromatics-O2 adduct. Formations of maleic anhydride was observed in the case of o-xylene and it is suggested that maleic anhydride is produced from cis-2-butenedial. Formation of 3-hexene-2,5-dione (unsaturated γ-dicarbonyl) was observed from p-xylene. The ring-cleavage process accounts for 41, 55, and 36% of the total reaction in o-, m-, and p-xylenes, respectively.
Ring-cleavage Reactions of Aromatic Hydrocarbons Studied by FT–IR Spectroscopy. III. Photooxidation of 1,2,3-, 1,2,4-, and 1,3,5-Trimethylbenzenes in the NOx–Air System
Authors: Bandow Hiroshi , Washida Nobuaki
Published: July 2006

Photooxidation of 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes was carried out in the NOx–air system. Formation of glyoxal, methylglyoxal and biacetyl was observed in the cases of 1,2,3- and 1,2,4-trimethylbenzenes, and only methylglyoxal was observed from 1,3,5-trimethylbenzene. Yields of glyoxal, methylglyoxal and biacetyl were 7, 18, and 45% and 8, 37, and 11% of trimethylbenzene consumed in cases of 1,2,3- and 1,2,4-trimethylbenzenes, respectively. The reaction mechanism which was used to explain the yields of α-dicarbonyl compounds from toluene and o-, m-, p-xylenes in the preceding paper (part II) has been applied to explain these yields, and has been found to reproduce these yields well. Formation of 3-hexene-2,5-dione was observed only from 1,2,4-trimethylbenzene. The fractions of the ring-cleavage process in the total reaction were 70, 56, and 64% in cases of 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes, respectively. The yields of the ring-cleavage process are discussed.
Volatility of Low-Henry’s Constant Contaminants in Water
Authors: Okouchi Shoichi , Sasaki Sokichi
Published: July 2006

The volatilization rate of low-Henry’s constant contaminants (less than about 2 m3 Pa/mol) from water to the atmosphere was studied, together with the water volatilization rate, using tracer compounds under various mixing conditions. 1-Butanol, 1-pentanol, 1-hexanol, and 1-heptanol were used as the tracer compounds. The volatilization rates of these compounds and water were controlled by a mass-transfer process in the gas phase. The measured parameter was the ratio of the volatilization rate constant of a tracer(i) to that of water, Kv(i)/Kv(H2O). The obtained ratios agreed with those estimated theoretically. The volatilization rate constant of low-Henry’s constant contaminant(i) in environmental water, Kv(env)(i), can be estimated by multiplying the ratio, Kv(i)/Kv(H2O), by the environmental value of Kv(env)(H2O).
A Temperature Dependence Study of 35Cl NQR Frequencies in Dimethylammonium Hexachlorostannate(IV), Hexachlorotellurate(IV), and Hexachloroplatinate(IV)
Authors: Horiuchi Keizo , Ishida Hiroyuki , Nakamura Daiyu
Published: July 2006

The temperature dependence of 35Cl NQR frequencies was observed for [(CH3)2NH2]2SnCl6, [(CH3)2NH2]2TeCl6, and [(CH3)2NH2]2PtCl6. Two 35Cl NQR frequencies were recorded for the tin complex between 77 and ca. 260 K, the intensity ratio of which was 2:1 for the high- to the low-frequency line. An unusual temperature variation of both frequencies attributable to the motion of the cation was observed, and the existence of a phase transition was suggested. For the tellurium complex, the NQR frequencies were observed below ca. 240 K. At higher temperatures, two signals having the same intensity ratio as that of the tin complex were detected as expected from the isomorphous relation between both complexes proved at room temperature. A phase transition was newly located for this complex at 98 K in addition to another one at 171 K previously reported. The intermediate phase yielded three broad signals having equal intensity, whereas four broad lines could be detected in the low-temperature phase where more than four lines may be expected by referring to the temperature-dependence curves of the NQR lines.
Hydrophobic Indexes for Various Monosaccharides
Authors: Miyajima Koichiro , Machida Katsunosuke , Nakagaki Masayuki
Published: July 2006

The hydrophobic and the hydrophilic surface areas of seven kinds of monosaccharide molecules were calculated by using Hermann’s method. The hydrophobic indexes (Index A and Index B) which are defined as the ratio of the hydrophobic and the hydrophilic surface areas of the molecule are clearly correlated with the partition coefficient of monosaccharide between polystyrene gel and water, and the free energy change of transfer of monosaccharide from water to 1-butanol, indicating that the fraction of the hydrophobic surface area plays an important role in the interaction of monosaccharides and hydrophobic solutes in water.
Studies of Polystyrene-based Ion-exchange Fiber. III. A Novel Fiber-form Chelating Exchanger and Its Adsorption Properties for Heavy-metal Ions
Authors: Yoshioka Toshio
Published: July 2006

Fibrous chelating exchangers with –N(CH2COOH)2 and –N(CH2CH2COOH)2 groups have been prepared for the first time by using a polystyrene–polypropylene composite fiber as the starting material. They have large surface areas per unit of weight and can be utilized in various forms. The properties of adsorbing Cu2+ are compared between these chelating fibers and an ordinary chelating resin. The former groups form more stable complexes with Cu2+ than the latter, probably because of their different chelating structure. The rate of the adsorption of Cu2+ to the fibers is dependent upon their water content and is from ten to fifty times as high as that to the resin. These results are explained by assuming that the diffusion within the exchangers is the major rate-controlling step in the adsorption process. The diffusion equation of isotopic ion exchange for a cylindrical endless fiber was solved in the case of ideal particle-diffusion control by modifying the method used for a spherical resin. The experimental data are interpreted in terms of their theoretical solutions. For practical application, the removal of Cu2+ and Mn2+ from various solutions was also carried out by using fixed-beds of these chelating fibers.
Photoelectrochemical Behavior of p-Type Boron Phosphide Photoelectrode in Acidic Solution
Authors: Lee Ju-seong , Fujishima Akira , Honda Kenichi , Kumashiro Yukinobu
Published: July 2006

The photoelectrochemical behavior of p-type boron phosphide (p-BP) in acidic solution was investigated. The p-BP photocathode was stable in sulfuric acid solution under irradiation, and the band gap deduced from the photocurrent action spectrum in acidic solution was 2.0 eV. The gas evolved from p-BP photocathode was hydrogen which was obtained with a current efficiency of ca. 100%. The photocurrent was markedly increased by suitable ruthenium treatment of the BP. A photoelectrochemical cell (PEC), Pt(H2)/0.5 M H2SO4(1 M=1 mol dm−3)/ /0.5 M H2SO4/p-BP, was shown to have an open-circuit photovoltage of 0.45 V and a fill factor of 0.25.
Surface Treatment of meso-Carbon Microbeads by Oxygen Plasma
Authors: Sugiura Masaaki , Esumi Kunio , Meguro Kenjiro , Honda Hidemasa
Published: July 2006

A surface treatment of meso-carbon microbeads was carried out using an oxygen plasma to improve the wettability in aqueous solution. The surface acidity of meso-carbon microbeads increased with treating time and the pH of the aqueous dispersion shifted to lower values. The zeta potential varied with treating time from a positive to a negative value. Further, the turbidity behavior of aqueous dispersion with treating time was similar to that of surface acidity. From these results, it was found that the surfaces of meso-carbon microbeads were oxidized by oxygen plasma, resulting in an enhancement of wettability of meso-carbon microbeads in an aqueous solution.
A Nuclear Magnetic Resonance Study of the Exchange Reaction of Dimethyl Sulfoxide in Pentakis(dimethyl sulfoxide)oxovanadium(IV) Ions
Authors: Kaya Kiyoshi , Ikeda Yasuhisa , Fukutomi Hiroshi
Published: July 2006

The dmso exchange reaction in [VO(dmso)5]2+ has been studied in the mixture of CD3NO2 and DMSO by means of 1H NMR. The exchange rate is independent of the free DMSO concentration and the kinetic parameters are as follows: kex(25 °C)=1.76×103 s−1, ΔH\eweq=60.1±4.3 kJ mol−1, and ΔS\eweq=18.5±12.9 JK−1 mol−1.
Hydrophobic Vitamin B12. IV. Addition Reactions of Alcohols to Olefins as Catalyzed by Hydrophobic Vitamin B12 Derivatives
Authors: Murakami Yukito , Hisaeda Yoshio
Published: July 2006

Addition reactions of alcohols to olefins were catalyzed by hydrophobic vitamin B12 derivatives under aerobic irradiation conditions at the room temperature range. Ethyl vinyl ether, 1-pentene, and cyclohexene were adopted as olefins, while heptamethyl methylaquacobyrinate perchlorate and heptamethyl cyanoaquacobyrinate perchlorate were used as the starting complexes. Heptamethyl cobyrinate, which was generated from heptamethyl methylaquacobyrinate perchlorate by aerobic photolysis, is an appropriate catalyst for investigation of the reaction mechanism because the alkylated complex having the cobalt–carbon σ-bond, the reaction intermediate, has a long lifetime sufficient for its identification in the dark. On the other hand, heptamethyl cyanocobyrinate, which was derived from heptamethyl cyanoaquacobyrinate, is superior to heptamethyl cobyrinate as the catalyst for the addition reaction. The reaction proceeds via light-promoted decomposition of the alkylated complex, and the catalyst is regenerated upon autoxidation by air. These hydrophobic vitamin B12 derivatives are particularly effective homogeneous catalysts for the addition of an alcohol to an electron-rich olefin. Plausible reaction schemes for the catalytic cycle have been presented on the basis of experimental findings.
Preparation of Michael Adducts of Isobutyraldehyde and Acetylenecarboxylic Esters via N-Isobutylidene-t-butylamine
Authors: Miyajima Shingo , Ito Kunio
Published: July 2006

N-Isobutylidene-t-butylamine reacted with methyl propiolate or dimethyl acetylenedicarboxylate to afford the Michael adducts predominantly. The adducts were converted to the corresponding formyl esters.
Three-dimensional Aromaticity of Ferrocene
Authors: Aihara Jun-ichi
Published: July 2006

The conjugated systems of ferrocene and related compounds were constructed using five equivalent 3d orbitals of iron and carbon 2pz orbitals of the cyclopentadienyl or pentadienyl groups. Ferrocene with such a conjugated system was found to have positive resonance energy due to cyclic conjugation, and was characterized as a three-dimensional aromatic species.
Decompositions of Tropone Tosylhydrazone Sodium Salt in the Presence of Cyclopentadienone Derivatives. [4+2]-Type Cycloaddition Reactions of Cycloheptatrienylidene or 1,2,4,6-Cycloheptatetraene with Cyclopentadienone Derivatives
Authors: Saito Katsuhiro , Ishihara Hiraku
Published: July 2006

Tropone tosylhydrazone sodium salt, the precursor of the cyclic conjugated carbene (cycloheptatrienylidene), was decomposed in the presence of various cyclopentadienone derivatives to give endo- and exo-[4+2]-type adducts and benzotropylidene derivatives. The product ratios between the endo-[4+2]-type adducts and the exo-[4+2]-type adducts are considered to suggest that these addition reactions proceed via a cyclic conjugated allene (1,2,4,6-cycloheptatetraene), which is a valence-bond isomer of cycloheptatrienylidene. Upon heating, the [4+2]-type adducts gave the benzotropylidene derivatives via decarbonylation reactions followed by 1,5-hydrogen shifts.
Constituents of Seeds of Brucea javanica. Structures of New Bitter Principles, Yadanziolides A, B, C, Yadanziosides F, I, J, and L.
Authors: Yoshimura Shin , Sakaki Toshiro , Ishibashi Masami , Tsuyuki Takahiko , Takahashi Takeyoshi , Honda Tadashi
Published: July 2006

Three new quassinoids and four new quassinoid glycosides were isolated from water-soluble fraction of methanol extract of seeds of Brucea javanica (L.) Merr, known as “Ya-dan-zi” in Chinese folklore and their structures were determined by spectral and chemical means. Yadanziosides F, I, J, and L were demonstrated to have antileukemic activity.
Structures of New Quassinoid Glycosides, Yadanziosides A, B, C, D, E, G, H, and New Quassinoids, Dehydrobrusatol and Dehydrobruceantinol from Brucea javanica (L.) Merr
Authors: Sakaki Toshiro , Yoshimura Shin , Ishibashi Masami , Tsuyuki Takahiko , Takahashi Takeyoshi , Honda Tadashi , Nakanishi Toshihiro
Published: July 2006

Quassinoid glycosides, yadanziosides A, B, C, D, E, G, and H, and two quassinoids, dehydrobrusatol and dehydrobruceantinol were isolated from seeds of Brucea javanica, and their structures were determined. These glycosides showed bitter taste and were demonstrated to have antileukemic activity.
Improved Catalytic Activity of Cyclopentadienylcobalt in the Preparation of Pyridines from Acetylenes and Nitrites
Authors: Wakatsuki Yasuo , Yamazaki Hiroshi
Published: July 2006

The catalytic activity of cyclopentadienylcobalt increases greatly upon introducing a methoxycarbonyl group into the cyclopentadienyl ring, and by carring out the reaction with a vigorous exclusion of oxygen. Among the precursors we have examined, the most active one was [Co(Cpz)(cot)] (Cpz=methoxycarbonylsubstituted cyclopentadienyl; cot=cyclooctatetraene) which can generate the active species at 100 °C.
Solvent Effects on Absorption Spectra of Substituted Azobenzenes
Authors: Sueishi Yoshimi , Asano Mari , Yamamoto Shunzo , Nishimura Norio
Published: July 2006

McRae’s formula including the quadratic term was applied to an analysis of absorption spectra of substituted azobenzenes in various solvents. It has been suggested that the interaction between the solvent dipole and the solvent-induced solute dipole plays an important role.
79Br and 127I Nuclear Quadrupole Resonance of Mixed Valency Compounds Ga2X4(X=Br, I)
Authors: Okuda Tsutomu , Hamamoto Hiroshi , Ishihara Hideta , Negita Hisao
Published: July 2006

79Br and 127I nuclear quadrupole resonances(NQR) were observed in α-Ga2Br4, β-Ga2Br4, and Ga2I4 at various temperatures. Resonance lines disappeared at 353, 335, and 448 K for α-, β-Ga2Br4, and Ga2I4 respectively. The wide separation of the 127I resonance lines in Ga2I4 may be attributed to the interaction between the Ga+ ions and the I atoms.
A Through Space/Bond Interaction Analysis on the Shape of Band Structure of Polynitrilomethylidyne
Authors: Aoki Yuriko , Imamura Akira , Teramae Hiroyuki
Published: July 2006

The concept of the through space/bond interaction presented by Hoffmann et al. was extended to study electronic states of polymers. The band shape of lone pair orbitals was investigated by truncating converged Fock matrices and overlap integrals except for the terms corresponding to the through bond and particular through space interactions. This method was used by applying the ab initio tight-binding crystal orbital method to three isomers of one-dimensional polynitrilomethylidyne, for which the dependences of the lone pair orbital energy on the wave number vector differ significantly from one another. The band shape of the lone pair orbital is related intimately to the interaction with H atoms. The effect of each through space interaction on the band shape of the lone pair orbital may be reasonably interpreted in terms of the symmetry of crystal orbitals. This method seems expedient for analyzing qualitatively lone pair bands of various polymers at the ab initio level.
Oxidation of Triose Reductone by Oxidizing Inorganic Radicals Generated by Pulse Radiolysis
Authors: Horii Hideo , Abe Yasuo , Taniguchi Setsuo
Published: July 2006

Triose reductone (2,3-dihydroxy-2-propenal) was oxidized by Cl2−·, Br2−·, (SCN)2−·, and N3· to produce a triose reductone radical which had an absorption maximum at 398 nm, ε=5500 M−1 cm−1 (1 M=1 mol dm−3) and decayed by second-order kinetics. The rate constants for the reactions of triose reductone with these oxidizing inorganic radicals were obtained. The pKa of this radical was found to be 1.4.
The Synthesis, and the Crystal and Molecular Structure of [Diaquatetrakis(thiocyanato)cobalt(II)mercury(II)]-N,N-Dimethylacetamide (1/2), CoHg(SCN)4(H2O)2·2{CH3CON(CH3)2}
Authors: Kinoshita Hisashi , Shimoi Mamoru , Ouchi Akira , Sato Shoichi
Published: July 2006

The new complex indicated in the title was synthesized and its crystal and molecular structures were determined by the use of a single-crystal X-ray diffraction method. The crystal is tetragonal, with the space group P\bar4, and the cell constants are a=12.124(5) and c=7.985(2) Å. The structure was solved using the heavy-atom method, and the final R value was 0.039. Two kinds of crystallographically independent mercury atoms in the unit cell are tetra-coordinated and they are in the tetrahedral geometry, where four sulfur atoms of the thiocyanate ions are ligated, respectively. The cobalt atom is hexa-coordinated, and is in an octahedral geometry, where four nitrogen atoms of the thiocyanate ions are coordinated equatorially, and two water oxygen atoms axially. Thiocyanate ions span mercury and cobalt atoms to form two-dimensional networks parallel to the (001) plane. The planar polymeric complexes are linked to the c-axis direction, through hydrogen bonds between coordinated water molecules and N,N-dimethylacetamide.
Reactions of Enolic Biotin Models
Authors: Kondo Hiroki , Miura Katsuhito , Seki Eiji , Sunamoto Junzo
Published: July 2006

In order to delineate the mechanism of biotin-dependent carboxylation reactions, the following model experiments have been carried out. In reactions of carbonate derivatives such as methyl chloroformate with 2-ethoxy-2-imidazoline (1), a putative enolic biotin model, or 2-imidazolidinone (2), the former showed a much higher reactivity to provide the methoxycarbonylated 1 (3). Reactions of 3 with benzenethiolate, cyclohexylamine and carbanions have also been investigated as a model of transcarboxylation from N-carboxybiotin to an acceptor substrate. Only carbanions attack the carbonyl carbon of 3, leading to rupture of the C–O bond, but not of the N–C bond. A net “carboxyl” transfer was effected with 1-methoxycarbonylimidazole (9) as a donor substrate. Implications of these results in biotin catalysis are discussed.
Benzofuran Derivatives. II. Synthesis of 2,3-Dihydrobenzofurans from Ethyl 2-Acylphenoxyacetates
Authors: Suzuki Tsuneo
Published: July 2006

Ethyl 3-alkyl-3-hydroxy-5-nitro-2,3-dihydro-2-benzofurancarboxylates were obtained from the reaction of ethyl 2-acyl-4-nitrophenoxyacetates with potassium hydroxide in dry dioxane. The relative ratios of the cis and trans isomers with respect to C-2 and C-3 stereochemistry varied according to the structure of the acyl group. When the acyl group was acetyl, propionyl, or isobutyryl group, the cis isomers (2-alkoxycarbonyl groups and 3-hydroxyl groups are cis) were exclusively obtained in high yields. On the other hand, a nearly equimolecular amount of the cis and trans isomers was obtained from the reaction of 2-formyl derivatives under the same conditions.
Ozonolysis of 3-Methyl-1-phenyl-4-phenylazo-5-pyrazolone
Authors: Matsui Masaki , Konda Akihiro , Shibata Katsuyoshi
Published: July 2006

In chlorinated solvents, 3-methyl-1-phenyl-4-phenylazo-5-pyrazolone (1) easily reacts with ozone to give benzene (2), phenol (3), chlorobenzene (4), o-chlorophenol (5), biphenyl (6), and 3-methyl-1-phenyl-2-pyrazoline-4,5-dione (7). The formation of these products is explained by an electrophilic ozone attack on the hydrazone tautomer 1′.
Electronic and Steric Effects of Alkyl Group on Denitrosation of 3-Alkyl-1-methyl-1-nitrosothioureas
Authors: Isobe Masayoshi
Published: July 2006

A series of 3-alkyl-1-methyl-1-nitrosothioureas with R=CH3, C2H5, cyclo-C6H11 (3), (CH3)2CH (4), C2H5(CH3)CH, and (CH3)3C were synthesized and their rates of acid catalyzed (pH<6.5) denitrosation measured. According to rate measurements in CH3COOD–D2O, the kinetic isotope effect kH:kD is 1.25 for 4. Except 3, a linear plot of logkR⁄kMe for the denitrosation of RNHCSN(NO)CH3  vs. σ* provides ρ*=−0.98 (r=−0.997). The significant factor affecting the rate-determining step of the denitrosation of these N-nitrosothioureas at pH 4.6 is the electronic effect of the substituent at the N3 position.
The Structure of Cellulose Produced by Acetobacter xylinum in the Presence of a Fluorescent Brightener. The Influence of Concentration of a Brightener in the Medium on the Structure of Cellulose
Authors: Kai Akira , Kitamura Hitoshi
Published: July 2006

The influence of the concentration of a brightener on the structure of cellulose from an Acetobacter culture in the presence of a fluorescent brightener was examined. At a brightener concentration above 0.05 wt%, the X-ray diffraction diagram of cellulose from an incubated medium was observed. Except for the intensity of the diffraction corresponding to the (020) plane of cellulose I, the intensity of diffraction of the (110) plane became very weak and diffraction of the (1\bar10) plane disappeared. A new diffraction, not corresponding to cellulose I or II, occurred inside. The position of each diffraction pattern was constant and independent of the concentration of the brightener. As the brightener concentration of the medium became lower, in the X-ray diagram of the dyed cellulose that was produced, the diffraction intensity of both the (1\bar10) and (110) planes of cellulose I increased, and a new diffraction pattern gradually disappeared. In the case of an extraction of dyed cellulose from an incubated medium with a brightener (above 0.05 wt%), the same result was obtained. The above results suggest that the monomolecular layer of a brightener is included between the (1\bar10) planes of the produced cellulose.
Reactions of NH Radicals. V. Photolysis of HN3 in the Presence of C3H8 at 313 nm
Authors: Kodama Sukeya
Published: July 2006

The photolysis of HN3 vapor in the presence of C3H8 was studied at 313 nm and 30°C. The main products were N2, H2, CH4, C2H6, C3H6, NH4N3, CH3NH2·HN3, C2H5NH2·HN3, and n- and i-C3H7NH2·HN3. The quantum yields of these products were measured as a function of the pressure of HN3 or C3H8. The following mechanisms for the main reactions was proposed: HN3+hν(313 nm)→N2+NH(a1Δ); NH(a1Δ)+HN3→2N2+2H, NH2+N3, and N2+N2H2* (2); NH(a1Δ)+C3H8→C3H7NH2*(n- and i-propylamine) (3); NH(a1Δ)+C3H8→NH (X3Σ−)+C3H8 (4); C3H7NH2*→CH3+C2H4NH2 (5); CH4+C2H4NH (6), C2H4+CH3NH2 (7), C2H5+CH2NH2 (8), C2H6+CH2NH (9), H2+C3H6NH (10), and NH3+C3H6 (11); C3H7NH2*+HN3→C3H7NH2+HN3 (12); C3H7NH2*+ C3H8→C3H7NH2+C3H8 (13). The rate constant ratios are: k3⁄k2=1.28; k4⁄k2=0.262; k6⁄k5=0.109; k7⁄k5=0.050; k8⁄k5=1.39; k9⁄k5=0.040; k10⁄k5=1.20; k11⁄k5=4.72; k12⁄k5=666 dm3 mol−1; k13⁄k5=860 dm3 mol−1. The formation ratio of n-C3H7NH2/i-C3H7NH2 was 1.55, regardless of the total pressure. The half-life of 1.78×10−10 s for C3H7NH2* was obtained by using the collision theory. The relative and absolute rate constants were compared for the reactions of NH(a1Δ) with CH4, C2H6, and C3H8; it was found that the relative yield for the insertion of NH(a1Δ) into a C–H bond increases with a decrease in the C–H bond dissociation energy.
Mechanism of Resonant Two-photon Transitions via Repulsive Intermediate States. Experimental and Theoretical Studies on I2 Vapor
Authors: Shiraishi Jun , Fujimura Yuichi , Nakajima Takeshi , Kawasaki Masahiro , Kasatani Kazuo , Sato Hiroyasu , Tanaka Ikuzo
Published: July 2006

Mechanisms of resonant two-photon transitions via repulsive intermediate states are experimentally and theoretically studied. Polarization ratios, Ω=σ∞⁄σ↑↑ (where σ∞ and σ↑↑ are the cross section of the two-photon transitions obtained by the circularly polarized light and that by the linearly polarized light, respectively) of the two-photon excitation of iodine vapor have been measured in the wavelength range of 420–510 nm. An expression for the polarization ratio for the two-photon absorption in which both simultaneous and sequential processes take place has been presented. The polarization ratios calculated by using the δ-function approximation for the repulsive intermediate states as a function of the laser frequency for the iodine molecule system explain qualitatively the experimental result. This indicates that both the simultaneous and the sequential process take place in the frequency region measured.
Motion of CF3 Groups and Phase Transition in [Cu4(CF3COO)4]·2C6H6 as Studied by 1H and 19F NMR Techniques
Authors: Kubo Atsushi , Ikeda Ryuichi , Sampedro Jose Antofnio , Inoue Motomichi , Nakamura Daiyu
Published: July 2006

The temperature variation of 1H and 19F nuclear spin-lattice relaxation times T1 in [Cu4(CF3COO)4]·2C6H6 was observed at different resonance frequencies. From the NMR experiments, it was found that this complex undergoes a first order phase transition at 130 K, which was confirmed by DTA measurements. In the room-temperature phase, 1H gave normal exponential magnetization recovery curves and logT1 linearly decreased with increasing 103T−1 whereas 19F gave nonexponential magnetization recovery curves, from which long- and short-T1 components could be derived. This indicates that the C3 reorientation of CF3 groups about their respective symmetry axis is responsible for 19F T1 and for 1H T1 as well through 1H-19F cross relaxation. This was confirmed from the coincidence of the logT1  vs. 103T−1 curve of the long component and that of 1H T1. A very small activation energy of 5.5 kJ mol−1 was obtained for the CF3 reorientation. For the low-temperature phase, both 1H and 19F yielded nonexponential magnetization decay curves.
ZnII-bearing Green Rust II and Its Spontaneous Transformation into ZnII-bearing Ferrite in Aqueous Solution
Authors: Tamaura Yutaka
Published: July 2006

When solutions containing FeII, ZnII, and SO42− ions were oxidized by a mixed gas of air and nitrogen at pH 6.7 (25 °C), a ZnII-bearing green rust II (GR-II), which is a uniform crystalline precipitate with a definite chemical composition, was formed. The mol ratio of ZnII/FeIIin the ZnII-bearing GR-II increased linearly with an increase in the ZnII/FeII mol ratio in the reaction solution. The distribution coeffient of ZnII between the solid (ZnII-bearing GR-II) and the solution phase is 3.3 times higher than that of FeII. The ZnII-bearing GR-II was spontaneously transformed into ZnII-bearing ferrite. In this reaction, Zn2+ ions in the ZnII-bearing GR-II are preferentially incorporated into the ferrites.
Spectrophotometric and Polarimetric Investigations on Complex Formation between Copper(II) and Cyclodextrins in an Alkaline Solution
Authors: Matsui Yoshihisa , Kinugawa Kohji
Published: July 2006

Copper(II) forms a 1 : 1 complex (CuCD), as well as a 2: 1 complex (Cu2CD), with cyclodextrin (CD) in an alkaline solution. An equilibrium constant (Kdsp) for the disproportionation reaction of Cuα-CD to Cu2α-CD and α-CD was determined by spectrophotometry and polarimetry to be ca. 17 in 1.0 mol dm3 NaOH at 25 °C. The Kdsp value gradually decreased with increasing NaOH concentration. A ligand-exchange reaction of CU2CD with ethylenediaminetetraacetic acid (EDTA) to give Cu(edta)2− and CD was also examined by means of spectrophotometry and polarimetry. The equilibrium constants (Klex) for the ligand-exchange reaction was evaluated to be ca. 2.1 for an α-CD system and ca. 1.2 for a β-CD system in 1.0 mol dm−3 NaOH at 25 °C. The Klex value decreased rapidly with increasing NaOH concentration. The role of OH− in the complexation of Cu(II) with CD is discussed on the basis of these results.
ESR Studies on Salicylaldehyde Schiff Base Complexes of Copper(II). II. Bis(N-cyclohexyl- and N-cycloheptyl-salicylideneaminato)copper(II) Complexes and Their Derivatives in Solutions
Authors: Yokoi Hiroshi , Takeuchi Akira , Yamada Shoichiro
Published: July 2006

Ten of the title complexes in frozen toluene solutions and occasionally in other solutions have been studied by the ESR method. Most of the complexes showed both monomer and dimer ESR spectra simultaneously, and the equilibrium constant for 2 monomer\leftrightarrowsdimer has been determined by analyzing the concentration dependence of the intensity ratios of dimer and monomer ESR signals. The results indicate that the equilibrium constants of the complexes are dependent in a marked but subtle way, not upon the bulkiness of N-substituents, but upon both kind and position of the substituents introduced into the ligand benzene rings, and that the equilibrium constants are solvent-dependent. All the observed dimer ESR spectra were similar to each other, and computer simulation analysis of the spectra has revealed that the dimers formed in toluene have the same structures as that in green crystals of bis(N-cyclohexylsalicylideneaminato)copper(II). On the other hand, monomers of the title complexes have been found to show various degrees of tetrahedral distortion in the coordination geometry.
Interactions of Calcium Ions with Carbohydrates. The Crystal Structure of Calcium d-Glycero-d-gulo-heptonate Tetrahydrate
Authors: Taga Tooru , Kaji Taneno , Osaki Kenji
Published: July 2006

The crystal structure of the calcium salt of d-glycero-d-gulo-heptonic acid has been determined by the X-ray method. The crystal is monoclinic of space group P21 with unit-cell dimensions of a=10.064(1), b=10.540(2), c=11.340(2) Å, and β=108.92(1)°. The intensity data for 1754 unique reflections were measured with an automatic diffractometer. A trial structure, obtained by the direct method, was refined by the full-matrix least-squares method to R=0.030. The two independent heptonate anions have different conformations, and they chelate a calcium ion in different ways. The calcium ion is surrounded by eight oxygen atoms in a deformed dodecahedral form, the Ca···O distances ranging from 2.40 Å to 2.48 Å. The distortion of the moleular strcuture of the heptonate anions due to the calcium chelation was discussed in relation to the calcium-binding sites on a linear carbohydrate chain.
A New Aspect on the Origin of an Anomalous Substituent Effect on the Azomethine Proton Chemical Shifts in 4-Substituted N-Benzylideneanilines
Authors: Akaba Ryoichi , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

Carbon-13 chemical shifts, azomethine proton chemical shifts, and azomethine carbon–hydrogen coupling constants have been determined for N-benzylideneaniline and its several derivatives bearing o-methyl and/or p-nitro groups on the aromatic ring on the nitrogen atom (ring A). The anomalous upfield shift of the azomethine proton caused by introduction of a 4-nitro group on the ring A can be attributed to the increase in the twist angle θN of the ring A from the molecular plane containing the C=N bond.
Near-infrared Photocurrent of a Zinc Oxide Electrode Covered with Silver Atoms
Authors: Tanemura Hatsumi , Yonezawa Yoshiro , Hada Hiroshi
Published: July 2006

A near-infrared photocurrent has been observed in a sintered ZnO electrode whose surface was covered with Ag atoms. The photocurrent became more evident when silver deposition was carried out with a relatively large charging current. The importance of H+ reduction which competed with silver reduction is pointed out.
Equilibrium Solubilities of Benzene, Toluene, Ethylbenzene, and Propylbenzene in Silver Nitrate Solutions
Authors: Sanemasa Isao , Arakawa Seiji , Piao Cheng Yun , Deguchi Toshio
Published: July 2006

By making use of the solute vapor, the equilibrium solubilities of benzene and three alkylbenzenes in AgNO3 solutions have been measured. The complex formation constants of silver ions are estimated for each solute, and the results are compared with literature values.
Stereoisomers of the Bis(1,10-phenanthroline){(1R,2R)-1,2-cyclohexanediamine}cobalt(III) Complex
Authors: Tatehata Akira , Natsume Shigeru
Published: July 2006

The diastereomers of [Co(R-chxn)(phen)2]3+ (R-chxn=(−)589-(1R,2R)-1,2-cyclohexanediamine, phen=1,10-phenanthroline) were prepared and characterized by absorption, circular dichroism, and 1H NMR spectra. The preference of Δ-isomer in the complex formation was observed and the degree of the stereoselectivity was greater than that of the corresponding [Co(R-pn)(phen)2]3+ (pn= 1,2-propanediamine).
CD Spectra of 2,4-Dinitrophenyl Derivatives of α-Amino Acids Having Polynuclear Aromatic Group in the Side Chain. Absolute Configuration of 3-(9-Anthryl)alanine
Authors: Kawai Masao , Matsuura Taketoshi , Butsugan Yasuo , Egusa Syun , Sisido Masahiko , Imanishi Yukio
Published: July 2006

CD spectra of 2,4-dinitrophenyl (Dnp) derivatives of α-amino acids having polynuclear aromatic group in the side chain with l- and d-configuration showed negative and positive Cotton effect, respectively, around 400 nm in consistent with previously proposed Dnp-aromatic rule. Application of the rule revealed d-configuration of levorotatory 3-(9-anthryl)alanine, which was further confirmed by chiroptical comparison of the 2,4-dinitrophenyl derivative and its p-methoxyanilide.
Resolution of Alcohols as Esters by HPLC on (+)-Poly(triphenylmethyl methacrylate)
Authors: Okamoto Yoshio , Honda Shiro , Hatada Koichi , Yuki Heimei
Published: July 2006

Various secondary alcohols were resolved as benzoates or 3,5-dichlorobenzoates by high-performance liquid chromatography on optically active (+)-poly(triphenylmethyl methacrylate). Almost completely resolved alcohols include 2-butanol, 2-pentanol, 2-octanol, 3-octanol, 1-phenylethanol, cis-2-methylcyclohexanol, trans- and cis-3-methyl-cyclohexanol, and tetrahydrofurfuryl alcohol.
Kinetic Study of the Decay of Chlorine Dioxide in Supercooled and Glassy Organic Solvents
Authors: Ohta Nobuaki , Kuwata Keiji
Published: July 2006

Chlorine dioxide (ClO2), which is a stable free radical, decayed in supercooled and glassy liquid 3-methylhexane (3MHX) and 3-methylpentane near their glass transition temperatures (Tg’s). The decay of ClO2, however, was not observed in toluene or 2-methyl-1-propanol. The kinetic analysis of the decay of ClO2 in 3MHX is reasonably explained by its diffusional motion and dimer formation. The diffusion constants of ClO2 in 3MHX at temperatures around Tg were estimated in the analysis.
Collisional Deactivation of N(22P) Atoms by Simple Molecules
Authors: Umemoto Hironobu , Sugiyama Koichiro , Tsunashima Shigeru , Sato Shin
Published: July 2006

Cross sections for the quenching of N(22P) by a variety of simple organic and inorganic compounds have been determined by using a pulse radiolysis-optical absorption technique. It was found that N(22P) is less reactive than N(22D) in every case, despite its higher energy. The quenching cross sections for unsaturated hydrocarbons were found to be about one tenth of that for gas kinetic collisions, while those for saturated hydrocarbons and most inorganic substances were much smaller. The quenching cross sections for alkane hydrocarbons increase with the number of C–H bonds, and show a minor dependence on C–H bond strengths.
Synthesis of 5-O- and 6-O-Methyldihydrostreptomycin
Authors: Kishi Teruo , Tsuchiya Tsutomu , Koga Naokazu , Kobayashi Yoshihiko , Umezawa Sumio
Published: July 2006

5-O- and 6-O-Methyldihydrostreptomycin have been prepared from dihydrostreptomycin by a sequence of reactions involving methylation of a selectively protected derivative (4) with diazomethane in the presence of tin(II) chloride. The structures of the final products were confirmed by their 13C-NMR spectra and the TACu method.
Stereochemical Study on 1,3-Dipolar Cycloaddition Reactions of Heteroaromatic N-Ylides with Symmetrically Substituted cis and trans Olefins
Authors: Tsuge Otohiko , Kanemasa Shuji , Takenaka Shigeori
Published: July 2006

Stereochemistry of the cycloadditions of twenty-four heteroaromatic N-ylides with several symmetrically substituted cis and trans olefins has been investigated. Cyclic and acyclic cis olefins cycloadd to the and form of the ylides in a highly endo-selective manner giving almost quantitative yields of stereospecific endo 3+2 cycloadducts. N-Ylides stabilized with a substituent of carbonyl type react with trans olefins to form mostly two stereoisomeric 3+2 cycloadducts to the anti form of the ylides. In most cases, they undergo the stereospecific interconversion through a retro cycloaddition process, the isomer ratios and the easiness of transformation depending upon the nature and size of substituents on the five-membered ring which has been built up in the cycloaddition step. On the other hand, N-ylides stabilized with a substituent of noncarbonyl type react with trans olefins to give stereospecific and stereoselective 3+2 cycloadducts as single isomers which are assigned as the cycloadducts to the syn form of the ylides.
Preparation and Characterization of [Fe4S4(SFc)4]2− and [Mo2Fe6S8X3(SFc)6]3− (Fc=C5F4FeC5H5, X=EtS and MeO), and Their Catalytic Behaviors toward C2H2 Reduction
Authors: Tanaka Koji , Nakamoto Masami , Tashiro Yutaka , Tanaka Toshio
Published: July 2006

Iron–sulfur and molybdenum–iron–sulfur clusters with ferrocenethiolate, [Fe4S4(SFc)4]−2 and [Mo2Fe6S8X3(SFc)6]3− (Fc=C5H4FeC5H5, X=EtS and MeO), have been prepared as tetraalkylammonium salts. The reduction potentials of these clusters are more negative than those of the corresponding clusters with benzenethiolate suggesting that the ferrocencethiolate ligand has an electron donor ability stronger than the benzenethiolate ligand. Electronic absorption spectra reveal that the ferrocenethiolate ligand dissociates from the cluster anions in the electrochemically reduced states. The clusters can catalyze the reduction of C2H2 in water at pH 7.0 under the controlled potential electrolysis conditions. The rate of the reduction and the selectivity for the C2H4 formation are largely dependent on the clusters; the iron-sulfur cluster shows a higher activity than the molybdenum-iron clusters in the C2H2 reduction.
Activity and Selectivity Regulation of Synthesis Gas Reaction over Supported Ruthenium Catalysts
Authors: Fujimoto Kaoru , Nobusawa Tatsuya , Fukushima Takakazu , Tominaga Hiro-o
Published: July 2006

The catalytic activities of supported ruthenium for synthesis-gas conversion to hydrocarbons was found to be in the following order:

TiO2>Nb2O3>ZrO2>SiO2>Ta2O5>Al2O3>V2O5>Mo3>WO3>MnO2>ZnO

Turnover frequencies of the supported ruthenium increased with decrease in dispersion of the metal particles for every carrier material. Even the activities per unit weight of metals were higher for low-dispersion ruthenium on Al2O3, TiO2, and ZrO2. The chain-growth probability of a hydrocarbon product, which is characterized by the Schulz-Flory distribution, increased markedly with decrease in the metal dispersion irrespective of the carrier material. The catalytic activity of ruthenium particles with a dispersion level of 0.7 or higher reached a ceiling level at about 0.5 MPa, whereas that of low dispersed ruthenium increased almost linearly with an increase in reaction pressure (up to at least 2.0 MPa).