bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Surface Fluorination with CCIF3 on Catalytic Activity of SiO2–Al2O3 for Alkylation of Benzene with Propene
Authors: Kurosaki Akito , Okazaki Susumu
Published: July 2006

For surface modification, the vapor-phase fluorination of SiO2–Al2O3 with CCIF3 was carried out at various temperatures ranging from 350 to 550°C in a conventional flow reactor. It was found that surface fluorination at about 400°C was especially effective for the enhancement of both the catalytic activity and the maintenance of the catalytic activity for the vapor-phase alkylation of benzene with propene. Ammonia–TPD revealed that the surface acidity of SiO2–Al2O3 could be somewhat increased by surface fluorination at about 400°C. The vapor-phase adsorption of water, hexane, propene, benzene, and cumene showed that the SiO2–Al2O3 surface became hydro- and lipo-phobic after surface fluorination. Thus, an enhancement of catalytic activity maintenance was assignable to a decrease in the affinity of the catalyst surface to reaction products.
Topochemical Double Photocyclodimerization of Ris(butoxycarbonyl)-Substituted Tetrathiafulvalene in the Crystalline State
Authors: Venugopalan P , Venkatesan K
Published: July 2006

Crystals of bis(butoxycarbonyl)-substituted tetrathiafulvalene having three reactive double bonds yield upon irradiation two products, a “cage product” (II) as well as another (I) by the participation of a pair of reactive double bonds. The formation of both the products is understood based on the molecular packing in the crystal lattice. The circumstances leading to the formation of more than one photoproduct in the crystalline state and the question regarding the sulfur atom as a steering group in the context of crystal engineering are discussed.
Phosphorescence Emission of 2,6-Diacetylpyridine: Role of N-Heteroatom and Effect of Hydrogen-Bonding
Authors: Sarkar S K , Ganguly T
Published: July 2006

The absorption, excitation, and luminescence spectra of 2,6-diacetylpyridine (DAP) and acetophenone (ACP) are investigated in nonpolar methylcyclohexane (MCH) and polar ethanol (EtOH) matrices at 300 K and 77 K. The emitting state of DAP is found to be the lowest triplet state of essentially nπ* nature. In the emitting lowest triplet nπ* states of DAP and ACP the carbonyl group is observed to be the chromophore. The comparative studies on the photophysical properties of DAP and ACP reveal that the introduction of a pyridinic nitrogen atom in the phenyl nucleus of ACP leads to large nonradiative transitions from the lowest 3noπ* due to vibronic interaction between this state and the pyridinic nNπ* state. In the case of ACP a weak ππ* fluorescence, in addition to phosphorescence is observed in EtOH glass matrix at 77 K. On the other hand in EtOH no such fluorescence is detected for DAP. The phosphorescence decay profile of DAP in presence of EtOH is found to be of single exponential indicating emission from a particular excited electronic state. It is suggested that due to comparatively much weaker hydrogen-bonding interaction between DAP molecule and EtOH solvent both intersystem crossing and internal conversion rates are little affected.
Heterogeneous Photocatalysis. VIII. Zinc Sulfide Catalyzed Hydrogen Formation from Water in the Presence of Sodium Formate
Authors: Kisch Horst , Bücheler Joachim
Published: July 2006

A suspension of n-ZnS in aqueous sodium formate photocatalyzes formation of hydrogen (72%) and carbon monoxide (27%). The stoichiometry of the hydrogen producing reaction is determined as HCO2Na+H2O=H2+HCO3Na. The quantum yield at 290 nm is 0.24 mol H2/Einstein and its wavelength-dependence parallels that of the anodic photocurrent measured photoelectrochemically. Reaction rates increase linearly with increasing light-intensity and do not change when the temperature is increased up to 70°C. No gaseous products are formed when nonaqueous formic acid is employed instead of formate, or when ZnS is dehydrated at 250°C before use or when CdS is substituted for ZnS. When THF or sulfur compounds are added to the solution, H2 is the only gaseous product. The dependence of the reaction rate on formate concentration points to a Langmuir-type adsorption of formate onto the semiconductor surface, Kads=26 M−1. In D2O/HCO2Na the initial rate does not change but the amount of CO increases to 60% and photocorrosion is much stronger than in H2O; the initial isotopic composition of 85, 10, and 5% changes to 63, 30, and 7% of D2, HD, and H2, respectively, when 400 mL of gas has been produced. In H2O/DCO2Na the rate decreases by a factor of 1.3 and the amount of CO is only 15%; only H2 but no D2 and HD are detectable. The hole scavenger KSCN does not influence the quantum yield of hydrogen formation while the electron scavenger NaNO3 induces a strong decrease and completely inhibits CO formation. Stern–Volmer analysis indicates that nitrate scavenges in addition to conduction band electrons also an intermediate CO2− radical. The latter has been identified by spin-trapping experiments.
N-Chlorosuccinimide-Promoted Oxidative Decarboxylation of α-Amino Acids in Aqueous Alkaline Medium
Authors: Ramachandran M S , Easwaramoorthy D , Rajasingh V , Vivekanandam T S
Published: July 2006

Kinetics of oxidation of twelve α-amino acids (AA) by N-chlorosuccinimide (NClS) in aqueous alkaline media have been studied and compared with those of N-bromosuccinimide (NBS) oxidation. Analysis of the results shows that the observed rate of oxidation is first-order in [oxidant] and zero-order in [substrate]. The rate of oxidation increases with increase in [OH−]free in [NClS], the exception being the amino acids having β-alkyl substituent such as valine, leucine etc. Perusal of the results shows that NC1S/NBS reacts with α-amino acid anion to produce α-amino acyl hypohalite which then decomposes in the rate-determining step to give the products. The intermediate α-amino acyl hypohalite is identified by UV-visible absorption spectra. Glycine behaves differently from other amino acids in both oxidants. The proposed mechanism is consistent with the observed kinetics.
Carbon-13 NMR Study of Naphthylmethanide Ions in Polar Solvents
Authors: Yokoyama Yukihiro , Takahashi Kensuke
Published: July 2006

The 13C NMR parameters for 1- and 2-naphthylmethanide ions were obtained in two polar solvents, THF and HMPA. Excess charge distributions in the ions are discussed in connection with the nature of the solvents.
An Improved Cyanoalkylation Method of Aldehydes Catalyzed by Electrogenerated Base in a DMF–H2O System
Authors: Torii Sigeru , Kawafuchi Hiroyuki , Inokuchi Tsutomu
Published: July 2006

Electrogenerated base (EG base) formed in a DMF–H2O (1.85 M)–Et4NOTs (0.1–0.2 M)–(Pt) system is effective for condensation of phenylacetonitrile and its related compounds with aldehydes, giving the corresponding cyanoalkylation compounds in good yields, and the concomitant dehydration of the adducts is minimized.
Preparation of 2-Oxabicyclo[2.2.2]oct-5-ene, 1,4-Dimethyl-2-oxabicyclo[2.2.2]oct-5-ene, and 6-Oxabicyclo[3.2.1]oct-3-ene
Authors: Inouye Yoshinobu , Tokuhisa Kenji , Mitsuya Morihiro , Kakisawa Hiroshi
Published: July 2006

Three bicyclic olefins having an allylic oxygen atom (see title) were prepared. Of those, 2-oxabicyclo[2.2.2]oct-5-ene could not be isolated in its pure state due to the volatility of the compound. The other two, however, could be isolated.
A Conductance Study of Zinc Halides and Perchlorate and of Magnesium Perchlorate in Propylene Carbonate–Tetrahydrofuran Mixtures at 25°C
Authors: Al-Najar A A , Abbo H S
Published: July 2006

The electrical conductances of zinc halides and perchlorate and of magnesium perchlorate in propylene carbonate (PC)–tetrahydrofuran (THF) (1:1 in volume) have been measured at 25 °C. The conductance data were analysed by a minimization technique using the Lee/Wheaton (L/W) and Murphy/Cohen (M/C) equations. The results indicate that all of these salts behave as “weak electrolytes”. Zinc and magnesium perchlorates were found to be anomalous in showing unusually high molar conductance, and in exhibiting a pronounced maximum conductances at low concentrations. Also, it was found that the mode of ionization is specific for the anion involved.
Rhodium Carbonyl Catalyzed Carbonylation of Unsaturated Compounds. IV. Carbonylation and Oligomerization of Diphenylacetylene Catalyzed by Co4(CO)12, Rh4(CO)12, and Ir4(CO)12 under Pressure of Carbon Monoxide
Authors: Hong Pangbu , Mise Takaya , Yamazaki Hiroshi
Published: July 2006

In the presence of Co4(CO)12, Rh4(CO)12, and Ir4(CO)12 catalysts the reaction of diphenylacetylene (1) in 2-propanol under pressure of carbon monoxide gave the hydrocarbonylation products 2 and/or 3 and the oligomers 4 and/or 5, in which the ratios depended on the catalyst employed.
Photoelectrochemical Study of n-InP: Redox Processes Using Electroluminescence as Mechanistic Probe
Authors: Manivannan Ayyakkannu , Hashimoto Kazuhito , Sakata Tadayoshi , Fujishima Akira
Published: July 2006

Electroluminescence (EL) due to band-band transition was observed for n-InP single crystal electrodes in solutions containing current doubling reagents like peroxodisulfate and various redox electrolytes. The mechanism for the EL emission in relation to surface properties of n-InP crystals in these electrolytes is presented. The cathodic decomposition process of n-InP electrodes involved in various electrolytes especially in peroxodisulfate medium has been analyzed from the EL emission as a function of electrode potential under steady state as well as pulsed conditions. The intensity of the EL signal depends on the electron density at the interface which is controlled by the potential and on the chemical composition of the electrode surface. Moreover, a hydrogen evolution reaction reduces the EL efficiency at higher cathodic potentials. Though the potential has no effect on the shape of the EL spectra, a significant change in EL intesity was observed. In all the electrolytes used the InP electrodes seem to decompose during cathodic polarization to form indium metal. The change in the surface composition plays an important role in the relation between potential and the EL intensity. Moreover, during pulsed polarization the EL behavior is different from the steady state conditions and also depends on the concentration of the electrolyte species.
Stability and Resonance Energy of Troponoid Compounds
Authors: Kurihara Teruo , Ishikawa Sumio , Nozoe Tetsuo , Aihara Jun-ichi
Published: July 2006

The fundamental skeleton of the tropones possessing a unique heptagonal structure is predicted to be aromatic with positive resonance energies and conforming to the topological charge stabilization rule (TCS rule). Similarly, naturally occurring tropolones also nicely fit the theory that conformity to the TCS rule gives a stable molecular system. Thus, many of the troponoids so far synthesized and those occurring in nature are energetically very stable molecules as well as being synthetically very accessible. The TCS rule applies very well to the formation mechanism of heterocycle-fused tropones. It is very likely that there are various reaction paths in nature which are compatible with the TCS rule for the formatin of tropylium compounds having annulated heterocycles.
Reaction of Organocobaloxime with Thiol under Irradiation
Authors: Kijima Masashi , Miyamori Kiyokatsu , Nakamura Tomoko , Sato Takeo
Published: July 2006

The reactivity of photoactivated organocobaloxime was investigated by the reaction of thiol. Alkyl(pyridine)cobaloxime and ethyl mercaptoacetate were irradiated with a tungsten lamp under anaerobic conditions in an organic solvent to give ethyl alkylthioacetate, diethyl 2,2′-dithioacetate, and ethoxycarbonylmethylthiocobaloxime. Mechanistic investigations were carried out to determine the reaction course. Sulfide was assumed to be produced via a homolytic substitution between alkylcobaloxime and disulfide formed during the reaction. Disulfide was formed from thiol catalytically in the presence of cobaloxime under anaerobic conditions. Homolytic methyl-transfer scarcely occurred from methylcobaloxime into thiol.
Catalysis of α-Fe and Fe1−xS toward the Hydrogenolysis of trans-Stilbene in Hydroaromatic Hydrocarbon Solvents
Authors: Futamura Shigeru , Fujimoto Ken-ichiro , Kamiya Yoshio
Published: July 2006

The Fe-catalyzed hydrogenolysis of trans-stilbene was carried out in aromatic hydrocarbon solvents at 380 °C. α-Fe and pyrrhotite catalyze bimolecular hydrogen transfer from hydroaromatic hydrocarbons to trans-stilbene and hydroaromatic hydrocarbon-mediated hydrogenolysis of trans-stilbene by molecular hydrogen at 380 °C. This catalyzed hydrogen transfer proceeds by radical mechanism. The product distribution is affected by the catalyst species. Pyrrhotite catalyzes the hydrogenation of trans-stilbene more effectively than α-Fe. Both the iron catalysts are inactive toward the cleavage of carbon to carbon single bond in bibenzyl.
Preparation and Characterization of a 345 nm Absorbing Reductant Derived from Dehydro-l-Ascorbic Acid
Authors: Tanaka Hidehiko , Kimoto Eiji
Published: July 2006

The addition of sodium hydroxide to an ethanolic dehydro-l-ascorbic acid solution produced a yellowish precipitate which was enriched by a reductant possessing absorption maxima at 345 and 225 nm. This reductant was purified by DEAE-Sepharose column chromatography and Cellulofine-gel chromatography; on the basis of physicochemical analyses it was deduced to be the 2,3-enediol form of 2,3-diketo-l-gulono-δ-lactone (2,3,6-trihydroxy-4-oxo-2-hexen-5-olide). The process, derived from dehydro-l-ascorbic acid, involved a hydrolytic cleavage of a 5-membered γ-lactone ring, conversion to the 2,3-enediol form and rearrangement to 6-membered δ-lactone. The marked bathochromic shift of the absorption maximum of this reductant from that of ascorbic acid (265 nm) could be due to an extended conjugation among the enediol group and two carbonyl groups on both sides.
Facile Reduction of Dithiocarbonates Derived from Secondary Alcohols with n-Bu3SnH–Et3B and Synthesis of 2-Furanthiones and 2-Furanones by Intramolecular Addition of Alkoxythiocarbonyl Free Radicals to Acetylenic Linkages
Authors: Nozaki Kyoko , Oshima Koichiro , Utimoto Kiitiro
Published: July 2006

The reduction of dithiocarbonates or thiocarbonates by n-Bu3SnH–Et3B easily gives the corresponding hydrocarbons. The intermediate alkoxythiocarbonyl radical equivalents are trapped by properly located carbon–carbon multiple bonds. The dithiocarbonates derived from either homopropargylic or homoallylic alcohols produce tetrahydrofuranones upon treatment with n-Bu3SnH–Et3B. Application of this new method to the conversion of carbonyl compounds into olefins is also described.
The Catalytic Activity of Hydrous Zirconium Oxide Calcined at Several Temperatures
Authors: Shibagaki Makoto , Takahashi Kyoko , Kuno Hideyuki , Matsushita Hajime
Published: July 2006

Hydrous zirconium oxide is an amorphous solid and has several catalytic activities. The oxide was changed to crystalline zirconia by calcination at a high temperature, and the catalytic activities were lowered. The correlation between the surface property and the catalytic activity was investigated on hydrous zirconium oxide calcined at several temperatures; the best activity was obtained in the oxide calcined at 300°C.
Studies of the Hydrous Silicon–Titanium(IV) Oxide Ion Exchanger. II. Affinity for Various Cations and Thermal Stability
Authors: Yamazaki Hiromichi , Kanno Yasuhito , Inoue Yasushi
Published: July 2006

The affiinity for various cations and the thermal stability were studied on hydrous silicon–titanium(IV) oxide ion exchangers with various titanium contents. An exchanger with 52 mol% Ti shows a higher affinity for an alkali metal ion having a smaller hydrated radius but similar affinity, which depends little on the pH′s of solutions, for alkaline earth metal ions, except for Ba2+. In the sorption of transition metal ions, the formation of a covalent bond is a factor in determining the selectivity of the exchanger, along with the remote coulombic interaction. The composition dependence of the affinities for Cs+, Ba2+, Co2+, Eu3+, and UO22+ was explained in terms of the acid-base properties of the exchangers. The exchangers with 37 to 67 mol% Ti do not suffer from any drastic change in the surface area and in the crystallinity upon heating up to 540 °C, and are much more heat-resistant than the component simple hydrous metal oxides. The degree of the decrease in the exchange capacity upon heat treatment is larger in exchangers with a higher titanium content. The effect of a heat treatment on the acid-base property and the affinity for cations was also studied.
Selenium Content and Its Oxidation State in Igneous Rocks, Rock-Forming Minerals, and a Reservoir Sediment
Authors: Tamari Yuzo , Ogawa Hideaki , Fukumoto Yuji , Tsuji Haruo , Kusaka Yuzuru
Published: July 2006

The selenium content of 188 samples (115 igneous rocks, 46 sedimentary rocks, and 27 sediments, including 38 rock-forming minerals and 25 rock reference materials) issued from the Geological Survey of Japan were determined. In these samples selenium was distributed over a wide range of concentrations, 0.1–19500 ng g−1. Especially, selenium was rich in alkali-feldspar (7.5–149 ng g−1) as well as in plagioclase (3.6–147 ng g−1), though not in mica (2.4–14.8 ng g−1) and quartz (0.6–6.4 ng g−1). Selenium, rich in feldspar, was easily dissolved as selenite with CO2-bubbling water. In a reservoir sediment-core (from the surface to 15-cm depth), selenite and much organically-complexed selenium were dissolved with 0.1 M hydrochloric acid and the subsequent 1 M sodium hydroxide solutions, respectively.
Salen-Capped Porphyrins as an Active Site Model of Metalloenzymes: Synthesis and Their Intramolecular Interactions between the Metal Complexes
Authors: Maruyama Kazuhiro , Kobayashi Fumikazu , Osuka Atsuhiro
Published: July 2006

Reversible Schiff base condensation of bis(salicylaldehyde)-linked porphyrins and ethylenediamine under high dilution gave salen-capped porphyrins in high yields. Site selective insertion of nickel(II) into the salen and zinc(II) into the porphyrin gave the corresponding Ni–Zn heterobinuclear complexes. The geometrical relationship between the two metal centers was estimated by 1H NMR spectroscopy. The porphyrin π electronic state of these Ni-salen-capped Zn-porphyrins was perturbed by their Ni-salen cap, which was studied by 400 MHz 1H NMR, UV-Vis spectra, fluorescence, and cyclic voltammetry measurements.
Spiral Growth on the Metal Complex Crystal
Authors: Tange Koichi , Suzuki Kazuo , Sasaki Ken-ichi , Kuroda Yasushige , Yoshikawa Yuzo
Published: July 2006

Spiral growth patterns were found on the crystals of (+)d-and (−)d-[Co(ox)(en)2]Cl·4H2O. The handedness of the spirals was statistically counted on each enantiomeric complex crystal. No stereoselectivity of the handedness suggests that the visible spirals do not arise from the molecular or crystal structural origin, but more macroscopic one.
In Situ Observation of a Dynamically Light-Induced Morphological Transformation at an n-MoS2 Electrode Surface by a Scanning Tunneling Microscope
Authors: Hinokuma Kohichiroh , Sakamaki Kenji , Fujishima Akira
Published: July 2006

A scanning tunneling microscope (STM) under photoelectrochemical control was used to investigate an in situ dynamically light-induced morphological transformation at an n-MoS2 electrode surface in CH3CN by the addition of I− ions. The anistropic photocorrosion rate around the “disk-like” cavities was extremely slow due to the effects of the added I− ions when compared to the results achieved by adding only H2O.
Studies on Aromatic Sesquiterpenes. XII. Synthesis of (±)-cis-5-Hydroxycalamenene
Authors: Tanaka Juichi , Adachi Kazuo
Published: July 2006

Starting from o-cresol, (±)-cis-5-5-hydroxycalamenene was synthesized through 4-isopropyl-5-methoxy-6-methyl-1-tetralone as a key intermediate and identified with the natural compound spectroscopically.
X-Ray Structures of Molybdenum(V) Tetraphenylporphyrins, MoO(tpp)NCS·CH2Cl2 and MoO(tpp)F
Authors: Imamura Taira , Furusaki Akio
Published: July 2006

The molecular structures of the title complexes have been determined by a single-crystal X-ray diffraction method. The crystals of MoO(tpp)NCS·CH2Cl2 (tpp= 5,10,15,20-tetraphenylporphyrinato) and MoO(tpp)F are triclinic and tetragonal respectively. An isothiocyanate ion is coordinated to the central molybdenum atom at an angle of 145° with the Mo–N(NCS) bond through the nitrogen atom. In both complexes, the molybdenum atoms are displaced toward oxo ligands from the 4N plane composed of pyrrole nitrogens.
Polymerization of Lipid Bilayer Initiated by a Redox Initiator: Effect of Polymerization on Dyes in the Inner Water Phase
Authors: Hasegawa Etsuo , Kimura Noboru , Hatashita Masanori , Tsuchida Eishun
Published: July 2006

The polymerization of the liposomal lipid bilayers of phoshpolipids having one or two diene groups was studied by the use of a redox initiator (NaHSO3/K2S2O8) at low temperature (8 °C). The soluble and insoluble polymers were obtained, respectively. The membrane polymerization itself had small effect on the dye in the inner water phase.
Unit Subduced Cycle Indices with and without Chirality Fittingness for Ih Group. An Application to Systematic Enumeration of Dodecahedrane Derivatives
Authors: Fujita Shinsaku
Published: July 2006

Subduction of the coset representations of Ih point group produces tables of unit subduced cycle indices (USCIs) with and without chirality fittingness (CF). These indices are applied to the enumeration of dodecahedrane derivatives with respect to their molecular formulas as well as to their symmetries. The USCIs are effective to the enumeration of such derivatives as having only achiral substituents on the vertices of a dodecahedrane skeleton. On the other hand, the USCI–CFs are used for enumerating dodecahedrane derivatives with achiral and chiral substituents. Substitutions on the edges of the dodecahedrane skeleton are also discussed in terms of the present USCI approach.
The Electrochemical Study of Ag(II) Complexes of Polyaza Macrocycles and Their Acetic Acid Derivatives
Authors: Kodama Mutsuo , Mahatma Anung Budhi , Koike Toru , Kimura Eiichi
Published: July 2006

Although an attempt to isolate pure crystallines of Ag(II) complexes failed, we could prepare stable aqueous solutions of the Ag(II) complexes of [15]aneN5, [16]aneN5, and their acetic acid derivatives by disproportionation reactions of Ag(I) induced by these polyaza macrocycles, and have investigated their electrochemical redox behaviors using conventional voltammetric methods. All Ag(II) complexes including the [14]aneN4 (cyclam) complex undergo a reversible two-electron reduction at DME (dropping mercury electrode). From the potential where the i2⁄(i1–i) ratio is unity, the log formation constants were determined to be 43.4, 43.6, 43.3, 39.3, and 42.5 for the cyclam, [15]aneN5, [16]aneN5, cyclam-tetraacetic acid, and [15]ane5-pentaacetic acid complexes, respectively. Cyclic voltammetric (CV) oxidation scans at the glassy carbon electrode showed a reversible one-electron response (separation of anodic and cathodic peak potentials, ΔEp′=70 mV; the ratio of anodic and cathodic peaks, (ip)c⁄(ip)a′=1), which can be ascribed to a reversible Ag(III)/Ag(II) redox change. Though the acetate groups attached to the nitrogen atoms contribute to the net destabilization of the Ag(II) complexes, they exert a large positive effect on the thermodynamic stability of the Ag(III) state.
Association of C5–C9 Normal Alkanes with Cyclodextrins in Aqueous Medium
Authors: Sanemasa Isao , Osajima Tomonori , Deguchi Toshio
Published: July 2006

The complex formation of cyclodextrin (CyD, host) with C5 to C9 normal alkanes (guests) has been studied in aqueous medium at 25°C by making use of the volatilization rate of alkane molecules from aqueous into gaseous phase. In the excess of the host, β- and γ-CyDs form 1:1 complexes, while α-CyD forms 1:1 and 2:1 (host: guest) complexes. With an increase in the chain length of alkane, association constants for three CyDs increased; in the case of α-CyD, the 1:1 association constant for C9 was identical to that for C8, while the 2:1 association constant continued to increase. The cavity size of CyD, the alkane chain length, and hydrophobicity and surface area of alkane molecules were taken into account to discuss the host-guest inclusion mechanism.
Substituent Effects on the Carbon-13 NMR Chemical Shifts of Cyclopropyl Carbons in p-Substituted(cis- and trans-2-Chlorocyclopropyl)benzenes
Authors: Kusuyama Yoshiaki , Kagosaku Tamami , Hasegawa Takeshi
Published: July 2006

Carbon-13 chemical shifts have been measured for the cyclopropyl carbon atoms of twenty one p- substituted (cis- and trans-2-chlorocyclopropyl)benzenes. The substituent induced chemical shifts (SCS) for the trans derivatives are shifted down field by electron-acceptor substituents and upfield by electron-donating substituents (normal SCS). This SCS trend is the same as those observed for the p-substituted cyclopropylbenzenes, while the SCS range is small because of the decreased polarization of C-1–C-2 bonding due to the attached chlorine atom. For the cis derivatives, SCS for C-1 and C-3(CH2) carbons were also normal, while no measurable SCS was observed for C-2(CCl). The SCS well fitted with the LSFE equation, indicating that the SCS were controlled mainly by a polar effect, except for C-2(CCl, cis).
Diene-Transmissive Diels–Alder Reaction of α,β: α′,β′-Unsaturated Thioketones
Authors: Motoki Shinichi , Matsuo Yoshihisa , Terauchi Yasuhiro
Published: July 2006

Diene-transmissive Diels–Alder reaction of l,3-bis(p-tolylmethylene)-2-propanethione has been investigated. The cycloadducts obtained by the reaction of the thione with dimethyl acetylenedicarboxylate and diethyl azodicarboxylate underwent Diels–Alder reaction further with various dienophiles to give sulfur-containing polycyclic compounds.
The Reaction of (Arylthio)trimethylgermanes with Various Haloalkanes —Steric Effect on the Reaction Mechanism—
Authors: Kozuka Seizi , Nitta Takemi
Published: July 2006

A kinetic study has been conducted on the reactions of (arylthio)trimethylgermanes with various haloalkanes. Bimolecular nucleophilic attack of the sulfur atom has been found as the mechanisms for the reactions with normal haloalkanes while the mechanism was found to deviate from bimolecular attack to unimolecular ionization of the haloalkane, dependent on the structure of the alkyl groups with increasing of the steric hindrance. Reaction of a secondary haloalkane also proceeded by unimolecular ionization.
Intramolecular Cycloaddition of the Azomethine Ylides Derived from α-Amino Acids or Esters and 5-Oxo-6-heptenals or 4-Oxo-5-hexenals
Authors: Kanemasa Shuji , Doi Kenji , Wada Eiji
Published: July 2006

Intramolecular cycloadditions of the azomethine ylides bearing a carbonyl-activated olefinic moiety, generated from α-amino acids or esters and 5-oxo-6-heptenals or 4-oxo-5-hexenals, produce the stereoselective internal cycloadducts either to olefin or carbonyl dipolarophilic function with normal or inverse regioselectivity, depending upon the types of ylides as well as the intervening chain length. Exclusively high diastereofacial selectivity has been achieved when 2-phenyl-4-thiazolidinecarboxylic acid and its methyl ester are utilized.
Acyliminium Cyclization of Several Chiral N-Alkenylsuccinimide Derivatives
Authors: Ohwada Jun , Inouye Yoshinobu , Kimura Motoko , Kakisawa Hiroshi
Published: July 2006

The acyliminium intermediate derived from (3R,4R)-N-(3-butenyl)-3,4-bis(benzyloxy)succinimide cyclized to give (8aS)- and (8aR)-hexahydro-3(2H)-indolidinone derivatives. On the other hand, those derived from N-3-hexenyl derivatives afforded (8aS)-hexahydro-3(2H)-indolidinone(s) exclusively. The geometry of the double bond reflected the stereochemistry of the products.
Photoinduced Hydrogen Evolution with Viologen-Linked Zinc Porphyrins
Authors: Okura Ichiro , Kinumi Yuichi
Published: July 2006

Viologen-linked water-soluble zinc porphyrins with different methylene chain lengths between porphyrin and viologen, Zn-PC3(CnV) (n=2–6), were both synthesized and characterized. The lifetimes of the photoexcited triplet states of these compounds were almost the same as those of zinc porphyrins without linked viologen. The fluorescence decay profiles, however, comprised two components with first-order decay (shorter and longer lifetimes) indicating the existence of two conformations: complexed and extended conformers. In the complexed conformer, photoexcited singlet state is quenched by linked viologen. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH, Zn-PC3(CnV), and hydrogenase under steady state irradiation. Upon irradiation of the sample solution hydrogen was generated, indicating that all of the compounds, Zn-PC3(CnV) (n=2–6), can be substrates of the enzyme hydrogenase, and that every compound participates as both a photosensitizer and an electron carrier in the same molecule.
Magnetic Study of N,N,N′,N′-Tetramethyl-p-phenylenediamine (Wurster’s Blue) Iodide Cation Radical
Authors: Yamauchi Jun , Fujita Hideo
Published: July 2006

One of the Wurster’s blue cation radicals, which is composed of the N,N,N′,N′-tetramethyl-p-phenylenediamine cation and iodine anion moieties, was prepared and its magnetic susceptibility measured from 2.6 to 300 K. The cation radical underwent no phase transition within this temperature range in striking contrast with the first-order phase transition observed in perchlorate and tetrafluoroborate salts, regardless of similar crystallographic structures. In addition, the temperature dependence of the magnetic susceptibility could be well-reproduced by a dimer model: a thermally accessible triplet state lying above a singlet ground state with an energy separation of ΔE⁄k=229 K. This behavior is controversial regarding the crystallographic determination. The unusual magnetic properties of the iodide salt were discussed, together with the crystal structure, ESR and visible absorption data, in comparison with those of the other salts.
Preparation and Reactions of 5-Aryl-1,4,2-dithiazolium Salts
Authors: Yonemoto Katsumi , Shibuya Isao , Tsuchiya Tohru , Yasumoto Masahiko , Taguchi Yoichi
Published: July 2006

S-Thioaroylsulfenamides (ArCSSNH2), formed by reaction of ArCSS−Na+ with hydroxylamine-O-sulfonic acid, were aroylated or acylated to give N-aroyl- or N-acyl-S-thioaroylsulfenamides, respectively, which were then cyclized with dehydration to afford 3-substituted 5-aryl-1,4,2-dithiazolium salts. The behavior of 3,5-diphenyl-1,4,2-dithiazolium perchlorate toward nucleophiles such as active methylene and amino compounds was studied systematically. The reaction can be classified into two cases depending on fission modes of initial adducts, i.e., ring opening–ring closure reaction (Path B) and fragmentation of dithiazole ring (Path C), and in some cases the initial adducts were isolated.
The Characterization and Cycloaddition Reaction of 5,6-Dihydro-1,3-dimethyl-6-methylene-5-[(substituted amino)methylene]-2,4(1H,H)-pyrimidinediones
Authors: Noguchi Michihiko , Kiriki Yasutoshi , Ushijima Takashi , Kajigaeshi Shoji
Published: July 2006

5,6-Dihydro-1,3-dimethyl-6-methylene-5-[(substituted amino)methylene]-2,4(1H,3H)-pyrimidinedione intermediates (E) were characterized spectroscopically and chemically. The cycloaddition reaction of E with olefinic dienophiles was carried out in highly regio- and stereoselective manners to give quinazoline derivatives.
The Behavior of Mixing in Liquid Binary Alloys. Volume of Mixing in the Systems Lead–Tin, Lead–Antimony, and Lead–Thallium
Authors: Badawi Walid A , El-Talbi Mohamed , Oun M Ahmed , Abu-Halguma A Said
Published: July 2006

The molar volume of mixing in the liquid systems Pb–Sn, Pb–Sb, and Pb–Tl has been studied by means of silica glass pycnometer at 1045, 907, and 773 K respectively. The volumes of mixing in the systems Pb–Sn and Pb–Tl are slight positive (0.0263×10−6–0.1767×10−6 m3mol−1), while that in the system Pb–Sb is slight negative (−0.1524×10−6 m3mol−1).
Ozonolysis of Pyrimidine Nucleosides
Authors: Matsui Masaki , Inoue Tooru , Shibata Katsuyoshi , Muramatsu Hiroshige
Published: July 2006

Cytidine, uridine, and thymidine are transformed into the ring-contracted 1-substituted derivatives by ozone. A plausible mechanism is proposed.
Kinetics of Dehydrogenation of 2-Propanol on La2−xSrxCuO4−y
Authors: Jeyalakshmi R , Jagannadhaswamy B , Rengaraj K , Sivasanka B
Published: July 2006

The catalytic properties of mixed oxides La2−xSrxCuO4−y (0.0≤x≤1.0 and y=non-stoichiometry) having K2NiF4 structure were investigated with regard to the effect of changes in the lattice parameters, the oxidation state of copper and oxygen nonstoichiometry in order to correlate the catalytic activity with physicochemical properties. The decomposition of 2-propanol was studied by pulse and flow reactor techniques. The flow reactor data was analyzed by statistical methods to deduce the mechanism on the basis of Langmuir–Hinshelwood and Hougen–Watson models. The reaction followed the first order kinetics with dual site surface reaction as the rate controlling step. The kinetic and thermodynamic parameters obtained from flow reactor data are comparable to those obtained from pulse reactor studies. The higher catalytic activity as indicated by low activation energy and higher conductivity value of La1.8Sr0.2CuO3.96 among the series have been attributed to the presence of higher concentration of Cu(III).
On the Gaussian Basis Set Extended by Their Derivatives with Respect to Scale Factor
Authors: Takahashi Atsuya , Miyazaki Tomoo
Published: July 2006

There has been discussion with regard to the effect of the ζ value, which is a parameter adopted in the Gaussian exponent on the molecular orbital results calculated by use of a basis set extended by their derivatives with respect to ζ. These results are compared with the effect of polarization functions on the molecular orbital results.
Solid State Multinuclear NMR Studies on M4(CO)12 (M=Co, Rh) and (NMe3Bz)2[Rh6(CO)15C]
Authors: Heaton Brian T , Sabounchei Javad , Kernaghan Stuart , Nakayama Hirokazu , Eguchi Taro , Takeda Sadamu , Nakamura Nobuo , Chihara Hideaki
Published: July 2006

Variable Temperature 13C MAS and 59Co NMR data on solid Co4(CO)12 show that there is a symmetry conserved reorientation of the CO4-tetrahedron which is more restricted than has been reported previously whereas the room temperature 13C MASNMR spectra of Rh4(CO)12 and (NMe3Bz)2[Rh6(CO)15C] are consistent with their solid state static structure.
Preparation and Characterization of [Co2(bidentate-N,S)3(triamine)]-Type S-Bridged Dinuclear Complexes
Authors: Konno Takumi , Okamoto Ken-ichi , Hidaka Jinsai
Published: July 2006

Three kinds of S-bridged dinuclear complexes, Δ- and Λ-[Co2(aet)3(dien)]3+ (aet=2-aminoethanethiolate and dien=diethylenetriamine), Δ- and Λ-[Co2(aet)3(dpt)]3+ (dpt=bis(3-aminopropyl)amine)), and ΔLLL-[Co2(l-cys-N,S)3(dien)] (l-cys=l-cysteinate), were prepared by the reactions of [Co(aet)3] or ΔLLL-[Co(l-cys-N,S)3]3− with [CoCl3(dien)] or [CoCl3(dpt)]. The isomers were characterized from their absorption, CD, and 13C NMR spectra.
A Novel Synthesis of 4B-Element-Containing Styrene Derivatives
Authors: Nagasaki Yukio , Kurosawa Koichi , Tsuruta Teiji
Published: July 2006

To synthesize 4B-group element-containing styrene monomers, alkylmetalation reactions of 4-methylstyrene (1) in the presence of lithium diisopropylamide (2) were investigated. Trialkylsilylation of 1 proceeded easily by the reaction with trialkylsilyl chloride in the presence of 2 to form mono- and bis-trialkylsilylated methylstyrene. This synthetic method was expanded to other 4B-element-containing styrenes such as germyl and stannyl compounds.
Kinetics and Mechanism of Anation of cis-β-Diaqua(3,6-diazaoctane-1,8-diamine) Cobalt(III) in 30% (v/v) Ethanol–Water Medium
Authors: Chatterjee Debabrata , Mallick Debnath , De G S
Published: July 2006

The kinetics of the aqua-ligand substitution of the title complex [CoIII(trien)(H2O)23+] (trien=3,6-diazaoctane-1,8-diamine) with various substituting amino acid ligands L=glycine, Dl-alanine, l-proline, Dl-valine, and l-serine was studied spectrophotometrically as a function of incoming ligand concentration, pH (3.0–5.0) and temperature (45–60 °C). The results are consistent with an ion-pair dissociative mechanism.
New Optically Active Liquid Crystal Compounds: (+)-4-Alkoxyphenyl 4-[5-(2-Methylbutyl)-1,3-oxathian-2-yl]benzoates
Authors: Haramoto Yuichiro , Kamogawa Hiroyoshi
Published: July 2006

New liquid-crystal compounds, (+)-4-alkoxyphenyl 4-[5-(2-methylbutyl)-1,3-oxathian-2-yl]-benzoates (9), have been synthesized. The mesomorphic behaviors of these compounds were compared with those of (+)-4-(2-methylbutoxy)phenyl 4-(5-alkyl-1,3-oxathian-2-yl)-benzoates and (+)-4-(5-alkyl-1,3-oxathian–2-yl)phenyl-4-(2-methylbutoxy)benzoates; compounds 9 exhibit a cholesteric phase and their transtition temperatures to isotropic were found to be lower those of the corresponding compounds. These properties seem to originate in the wider molecular width caused by both the 2-methylbutyl group at the 5 position of the 1,3-oxathiane ring and the molecular bend in the 1,3-oxathiane ring.
The Structures of Cytotoxic Diterpenes Containing Bromine from the Marine Red Alga Laurencia obtusa (Hudson) Lamouroux
Authors: Takeda Satoshi , Kurosawa Etsuro , Komiyama Kanki , Suzuki Teruaki
Published: July 2006

Four new brominated diterpenes possessing parguerane or isoparguerane skeleton have been isolated from the title alga collected in the Japanese waters along with several known parguerol, isoparguerol, and deoxyparguerol congeners. The structures of three new compounds were determined by the chemical correlation with the corresponding known compounds. The structural elucidation of the remaining one was carried out on the basis of a combination of chemical and spectroscopic means including 2D NMR technique. One of the new metabolites has proved to be cytotoxic. The cytotoxic properties of the several chemically derived compounds in addition to the known diterpenes are also described.
Synthesis of a Chiral α-(Aminooxy)arylacetic Ester. I. A Route through Optical Resolution of a Racemic α-(Phthalimidooxy)arylacetic Acid
Authors: Iwagami Hisao , Nakazawa Masakazu , Yatagai Masanobu , Hijiya Toyoto , Honda Yutaka , Naora Hirokazu , Ohnuki Takashi , Yukawa Toshihide
Published: July 2006

A synthetic route has been developed to the synthesis of a chiral O-alkyloxime (S)-16, which can be a synthetic intermediate for a potent antipsedomonal cephalosporin antibiotic M-14659 (1). The oxime moiety in (S)-16 has a chiral center at the carbon atom adjacent to the oxygen atom. We have achieved that (S)-16 can be prepared via t-butyl 2-aminooxy-2-[3,4-(isopropylidenedioxy)phenyl]acetate [(S)-15] from an optically active α-(phthalimidooxy) acid (S)-12a which is obtained by resolution using quinine. It has been demostrated that M-14659 prepared from (S)-16 is completely free from its (R)-diastereomer.
Formation of 1,3-Oxathiole-2-thione and 1,2,4-Trithiolane Derivatives by the Catalytic Reaction of α-Diazocarbonyl Compounds with Carbon Disulfide
Authors: Ibata Toshikazu , Nakano Hirofumi
Published: July 2006

The rhodium(II) acetate-catalyzed decomposition of α-diazocarbonyl compounds such as substituted α-diazoacetophenones, cyclic diazoketones, cyclic diazodiketones, and α-diazo-β-ketoesters in carbon disulfide gave 1,3-oxathiole-2-thione derivatives in good yields. Diazomalonates also gave alkyl 5-alkoxy-2-thioxo-1,3-oxathiole-4-carboxylates together with 3,5-bis[bis(alkoxycarbonyl)methylene]-1,2,4-trithiolanes. The formation of 1,3-oxathiole-2-thiones can be explained by the intermediacy of zwitterionic intermediate containing rhodium(II) acetate formed by the reaction of carbon disulfide with ketocarbenoids generated in the catalytic decomposition of the diazocarbonyl compounds.
Preference of [6e/4p], [6e/5p], and [6e/6p] Conjugations in Determining Relative Stabilities of Fused Five-Membered Heteroaromatic Isomers
Authors: Inagaki Satoshi , Urushibata Masahiro
Published: July 2006

Ab initio molecular orbital calculations showed that fused five-membered heteroaromatics 1 (X=O, NH, S) could be slightly or almost equally stable relative to their isomers 2. The results suggest that the [6e/6p] triene conjugation is only a little in preference to (or in the balance with) the counteracting [6e/4p] and [6e/5p] conjugations. Kinetically, the isomers 2 were predicted from the qualitative orbital theory and the calculated HOMO energies to be more stable.
Synthesis and Chemiluminescence of Coelenterazine (Oplophorus Luciferin) Analogues
Authors: Teranishi Katsunori , Goto Toshio
Published: July 2006

In the case of chemiluminescence of coelenterazine, effects of conformation rigidity of and hydrogen bonding with the emitter, coelenteramide, on the chemiluminescence efficiency have been examined with several coelenterazine analogues synthesized. Conformational rigidity has a light enhancing effect, whereas decreasing light yield was observed by hydrogen-bond formation with the emitter.
Systematic Classification of Molecular Symmetry by Subductions of Coset Representations
Authors: Fujita Shinsaku
Published: July 2006

The notation based on the subduction of coset representations (the SCR notation) is presented for the systematic characterization of molecular symmetry. The positions of a parent skeleton are divided into orbits on which the corresponding coset representations (CRs) act. Each of the CRs is then subduced to the subsymmetry that characterizes a molecule derived from the skeleton. The resulting subduced representations are further reduced into CRs, which provide a basis of the SCR notation. The SCR notation is more discriminative than the point-group notation as well as than the framework-group notation. A new concept “unit subduced cycle index” is introduced in order to determine which subsymmetry is realized if we begin with a parent skeleton of a given symmetry.
Hydrogenation Pathway of Quinolines over Raney Nickel and Ru/C
Authors: Okazaki Hiroshi , Onishi Kiyotaka , Soeda Mahito , Ikefuji Yoshio , Tamura Ryuji , Mochida Isao
Published: July 2006

Quinoline, 2-methylquinoline, and 8-methylquinoline were hydrogenated over Raney nickel (R-Ni) under 10 atm hydrogen pressure at about 200°C and over ruthenium on carbon (Ru/C) under 100 atm hydrogen pressure at 150°C. All the substrates were commonly hydrogenated into the initial products, 1,2,3,4-tetrahydroquinolines. The initial products were competitively converted over R-Ni to the final products, decahydroquinolines, directly or via 5,6,7,8-tetrahydroquinolines which were mainly formed from the initial products by isomerization. Ru/C promoted exclusively the direct hydrogenation of 1,2,3,4-tetrahydro derivatives to the final products. The hydrogenation and isomerization of 1,2,3,4-tetrahydroquinoline was completely inhibited in the competitive hydrogenation of quinoline and isoquinoline over R-Ni. Such features of these substrates are explained by the strong basicity of 1,2,3,4-tetrahydroisoquinoline. Roles of 1,2,3,4-tetrahydroisoquinoline are much moderate on Ru/C, where the π-coordination may be important. The effects of methyl substituent and different reactivities of quinoline and isoquinoline are discussed in terms of the steric hindrance on adsorption, heats of hydrogenation, basicities, and electronic properties of the related compound, which are calculated according to the MNDO-PM3 method.
Characterization of Surface Oxide Layer of Iron Particles for Magnetic Recording II. Surface Oxide Layer of Further Oxidized Iron Particles in High Humidity
Authors: Makishima Akio , Yamamoto Yukihiro , Watanabe Kohji
Published: July 2006

The surface oxide layer of additionally oxidized iron particles for magnetic recording in high humidity (90%) and at 60°C was examined by Mössbauer spectrometry. The mechanism of deterioration was concluded to begin with oxidation: the deterioration of the saturation magnetization (Is) of iron particles was caused by a deterioration of the Is of the surface oxide layer; later deterioration was caused by an increase in the amount of the oxide layer. The specific gravity of the surface oxide layer became gradually reduced during the oxidation.
Cation Distribution in a Series of Mixed Ferrites MgxMn1.1−xSn0.1Fe1.8O4 by Means of Powder X-Ray Diffraction and 57Fe, 119Sn Mössbauer Spectroscopy
Authors: Yamada Koji , Ohshita Hiroyuki , Funabiki Shinya , Sakai Hiroshi , Ichiba Sumio
Published: July 2006

The cation distribution in a series of MgxMn1.1−xSn0.1Fe1.8O4 spinel ferrites has been studied by means of X-ray powder diffraction and 57Fe, 119Sn Mössbauer spectroscopy. All of these ferrites showed broad 119Sn Mössbauer spectra due to the hyperfine magnetic field from the ferrimagnetically ordered cations at the A and B sites. With increasing x the distribution of the hyperfine field at the Sn atom became broader and the hyperfine field decreased abruptly above x=0.825. This observation indicates that diamagnetic Mg2+ ions are excluded from the A site below x=0.55, but occupy the A site as well as the B site only above x=0.825. This result is consistent with the Rietveld analyses of the X-ray powder diffraction data. The 119Sn Mössbauer spectroscopy is shown to be a useful technique for studying the cation distribution of ternary spinels in which the site preference of cations can not be empirically predicted.
Recognition of Substrates by Immobilized Bienzyme Membranes
Authors: Higuchi Akon , Nakagawa Tsutomu
Published: July 2006

Glucose oxidase and/or ascorbate oxidase were immobilized (entrapped) in poly(l-leucine-co-Nε-benzyloxycarbonyl-l-lysin) using a spin casting method. Current shifts and time lags for immobilized single-enzyme and bienzyme membranes were investigated as a function of the substrate concentration at 37°C. The current shifts of l-ascorbic acid in the bienzyme membrane were found to be 2–3.5 times higher than those of a single-enzyme membrane. Both the time lags of l-ascorbic acid and d-glucose were found to depend on the concentration of the substrates for both single-enzyme and bienzyme membranes. The method was presented in order to estimate the concentration of two substrates simultaneously. The concentration of d-glucose and l-ascorbic acid in a model solution was simultaneously estimated from an analysis of the current shifts and the time lags using a nonlinear least-squares method as an example.
The Synthesis of Two 6-Acetyl-2,3-dihydro-5-benzofuranols Naturally Obtained from Baccharis conferta
Authors: Yamaguchi Seiji , Nitta Toshiyuki , Hosaka Tsutomu , Nishino Yuji , Kawase Yoshiyuki
Published: July 2006

6-Acetyl-2-isopropenyl-5-methoxy-2,3-dihydrobenzofuran was prepared from 2-isopropenyl-5-methoxy-2,3-dihydrobenzofuran via formylation, Grignard methylation, and oxidation. It was then converted to two racemic dihydrobenzofuran derivatives obtained from Baccharis conferta.
Vapor Liquid Equilibrium Behavior of an Ethyl Acetate–Ethanol–Toluene System at Atmospheric Pressure
Authors: Katayama Hirotake
Published: July 2006

The VLE data of 85 points for a system of ethyl acetate–ethanol–toluene were measured at atmospheric pressure. The results were examined by boilling-point calculations using two forms of the Wilson equation: one with constants of constituent binary systems and the other with constants from a least-squares fit minimizing the Q-function(gE⁄RT=Σxilnγi) of the ternary data. Two binary systems, ethyl acetate–ethanol and ethanol–toluene, show minimum azeotropic points. The normal boiling point of toluene is much higher than the boiling points of the other two substances by 32–3 K. Because the system had a complicated behavior, calculations using the Wilson equation had difficulty to accurately cover the entire area of compositions.