bluuebunny/crossref_metadata_2025 huggingface dataset:
Iodine- or Iodine Monobromide-Catalyzed Alkoxy–Alkoxy Exchange Reactions of Alkylalkoxysilanes: Formation of the Catalyst–Alkoxysilane Complexes and the Reaction Mechanism
Authors: Ito Katsuko , Ibaraki Takeshi
Published: July 2006

The formation of charge-transfer complexes of iodine and of iodine monobromide with alcohols and alkoxysilanes has been established spectroscopically, and the formation constants of iodine–ethoxytriethylsilane and iodine–diethoxydimethylsilane complexes has been determined as 0.55±0.01 and 0.61±0.02, respectively. On the basis of these observations and the kinetic information recently reported, the previously proposed mechanism for the iodine or iodine monobromide catalyzed alkoxy–alkoxy exchange reactions of alkoxysilanes is discussed afresh. It has been confirmed that a mechanism involving a four-centered transition state containing a CT-complex is most favorable.
Dual-Mode Behavior in Doping–Undoping of Polypyrrole with Alkanesulfonate
Authors: Shimidzu Takeo , Ohtani Akira , Honda Kenichi
Published: July 2006

Polypyrrole (PPy) films incorporated with a series of 1-alkanesulfonates, RnSO3− (CnH2n+1SO3−, n=3–10), were prepared by the electrochemical polymerization of pyrrole in H2O containing sodium salt of RnSO3−. The mass transfer in the PPy matrix of the RnSO3− incorporated PPy (PPy/RnSO3−) films were investigated by electrochemical measurements. The electrochemical properties of PPy/RnSO3− were affected by the chain length of the incorporated RnSO3−. The incorporation and release of cationic species into the PPy/RnSO3− matrix during an electrochemical oxidation–reduction of PPy were observed and the contribution of cationic species during the doping-undoping process was increased with the dopant size. The PPy/RnSO3− showed a dual-mode behavior during the electrochemical doping–undoping process.
Novel Syntheses of Arylcarbamic Esters from Carbon Dioxide and Aromatic Amine via a Zinc Carbamate
Authors: Yoshida Yasuhiko , Ishii Shigeru , Kawato Akinori , Yamashita Tadataka , Yano Masahiro , Inoue Shohei
Published: July 2006

Arylcarbamic esters were synthesized directly from carbon dioxide and an aromatic amine via a zinc carbamate. The alkylation of the reaction mixture of carbon dioxide, an aromatic amine, and diethylzinc with dialkyl sulfate formed alkyl arylcarbamate in a high yield. Also, 2-hydroxycyclohexyl diphenylcarbamate was obtained selectively in a good yield by the reaction of carbon dioxide, epoxycyclohexane, and ethylzinc diphenylamide. Other arylcarbamates of 1,2-cyclohexanediol were obtained by the reactions of carbon dioxide, an aromatic amine, diethylzinc, and epoxycyclohexane.
Retentive Solvolysis. 15. Salt Effect on the Retentive Phenolyses of 1-(p-Substituted phenyl)ethyl p-Nitrobenzoates. The Pattern of Salt Effect and the Number of Ion-Pair Intermediates in the SN1 Solvolysis
Authors: Kinoshita Tomomi , Shibayama Koichi , Ikai Keizo , Okamoto Kunio
Published: July 2006

The salt effect of sodium phenoxide on the polarimetric (kp) and titrimetric rate constants (kt) has exhibited pattern B for the phenolysis of optically active 1-(p-methylphenyl)ethyl p-nitrobenzoate (ROPNB; (1)) in pure phenol. The other patterns A, C, and D were previously observed for the phenolyses of 1-phenylethyl p-nitrobenzoates with p-MeO- (2), p-H- (3), and p-NO2-substituents (4), respectively. Thus, the kp–kt pattern changes in the order A→B→C→D as the stability of the intermediate decreases in the order of 2>1>3>4. All the kp–kt patterns can be correlated with the ion-pair stage for product formation, i.e., the pattern A with the second ion-pair intermediate and the patterns B, C, and D with the first one. The pattern of salt effect on the product distribution (% of ROPh, o- and p-RC6H4OH, and p-MeC6H4CH=CH2) for 1 is also compatible with the kp–kt pattern B.
Synthesis and Properties of Dinitromethylated Arenes. Reinvestigation of the Ponzio Reaction
Authors: Suzuki Hitomi , Takaoka Hiroshi , Yamamoto Hidetoshi , Ogawa Takuji
Published: July 2006

Several title compounds have been prepared by the modified Ponzio procedure and their IR, 1H and 13C NMR data are presented. In some cases trinitromethylated arenes were obtained as a by-product. Oxidative cleavage to parent aldehydes and oxidation to carboxylic acids were the major competing reactions. 9-Anthracenecarbaldehyde oxime and 10-methyl-9-anthracenecarbaldehyde oxime reacted with nitrogen dioxide in an unexpected way, giving 10-nitro-9-anthracenecarbonitrile oxide and 10-methyl-10-nitro-9-anthrone as the respective main products. Nitration of (dinitromethyl)benzene has also been examined under various conditions.
Effect of Pore Diffusion in Liquid-Phase Enantioselective Hydrogenation with Ni–SiO2 Catalysts
Authors: Nitta Yuriko , Imanaka Toshinobu
Published: July 2006

A series of Ni–SiO2 catalysts, having a constant Ni loading and different Ni crystallite sizes, were prepared by using series of silica supports with controlled wide-pore structure. The crystallite size effect in enantioselective hydrogenation was found to hold also for the reactions controlled by the pore diffusion.
Kinetic Studies of Fast Equilibrium by Means of High-Performance Liquid Chromatography. XVII. Separation of Tautomers of 1,3-Cyclohexanediones
Authors: Moriyasu Masataka , Kato Atsushi , Hashimoto Yohei
Published: July 2006

Tautomers of 1,3-cyclohexanediones have been separated by means of low-temperature high-performance liquid chromatography (HPLC). The ratios of keto and enol-forms have been found to be highly solvent dependent, which is explained in terms of solute–solvent and solute–solute hydrogen bonding.
Photo-Excitable Membranes. Effects of pH of the Solution on the Photoresponse of Poly(vinyl chloride) Membrane Doped with a Spirobenzopyran Derivative
Authors: Anzai Jun-ichi , Hasebe Yasushi , Ueno Akihiko , Osa Tetsuo
Published: July 2006

The magnitude of the photoinduced membrane potential across a poly(vinyl chloride)/spirobenzopyran membrane depends considerably on the pH of the solution adjacent to the membrane surface which is exposed to light. The photoresponse is enhanced in the acidic region, while is depressed in the alkaline region. The results are explained in terms of the formation of the asymmetric membrane and of the charge density on the membrane surface.
Effect of the Aggregation Number on Gel Chromatographic Patterns of Micellar Systems
Authors: Funasaki Noriaki , Hada Sakae , Neya Saburo
Published: July 2006

Gel chromatographic patterns and their derivatives of micellar systems are predicted as a function of the total surfactant concentration and the aggregation number m by plate theory and asymptotic theory. These predicted patterns provide the basis for estimation of monomer concentration and m from experimental chromatographic data.
Preparation of Highly Pure Lithium and Sodium Fluorides Using Solvent Extraction
Authors: Kobayashi Kenji
Published: July 2006

LiF and NaF can be purified by solvent extraction. The impurity concentrations in the purified NaF are 2.5 ng g−1 for chromium, 60 ng g−1 for iron, 0.03 ng g−1 for cobalt, and 1.5 ng g−1 for copper. The concentrations in the purified LiF are 42 ng g−1 for nickel and 2.1 ng g−1 for copper.
Synthesis of Bis[1,2-bis(methylseleno)vinylenedithio]tetrathiafulvalene (TMSVT)
Authors: Nakano Hideyuki , Nogami Takashi , Shirota Yasuhiko
Published: July 2006

The title molecule was synthesized as an effective donor molecule for highly conductive organic complexes. It is a TTF dirivative possessing four selenium atoms and eight sulfur atoms. Its oxidation potential (E1⁄2) is 0.86 V vs. SCE in THF, which is slightly higher than that of VT and TMTVT.
Efficient Synthesis of Sterically Hindered Chiral Binaphthol Derivatives
Authors: Maruoka Keiji , Itoh Takayuki , Araki Yoshitaka , Shirasaka Tadashi , Yamamoto Hisashi
Published: July 2006

A highly effective method for preparation of a variety of sterically hindered chiral binaphthol derivatives has been described which involves the intramolecular 1,3-rearrangement of bis(trialkylsilyl ether) of chiral 3,3′-dibromo-1,1′-bi-2-naphthol with t-BuLi.
Crystal Structures of the Imidazole and the 1,4-Di(1-imidazolyl)butane Adducts of N,N′-Ethylenebis[salicylideneaminato]manganese(III) Perchlorate
Authors: Matsumoto Naohide , Takemoto Naohiko , Ohyosi Akira , Okawa Hisashi
Published: July 2006

Crystal structures of the titled compounds [Mn(Him)(salen)][ClO4]CH3OH (1) and [Mn(biim)(salen)][ClO4] (2), have been determined by the single-crystal X-ray diffraction method. The molecular structure of the imidazole adduct (1) is a binuclear structure bridged by phenoxy oxygen atoms of salen ligand, while that of the 1,4-di(1-imidazolyl)butane adduct (2) is a polynuclear structure bridged by imidazole nitrogen atoms of 1,4-di(1-imidazolyl)butane.
The Determination of a Small Amount of Biological Constituent by the Use of Chemiluminescence. XIV. The Flow-Injection Analysis of Protein Using Ultrasonic Chemiluminescence of Luminol
Authors: Hara Tadashi , Nakatsu Kazuhiro , Arai Akihiro , Yoshida Tatsunari , Tsukagoshi Kazuhiko
Published: July 2006

A flow-injection analysis method for the determination of a small amount of protein has been established by the use of the ultrasonic chemiluminescence of luminol. The present method was based on the phenomenon that the catalytic activity of cobalt(II) for the ultrasonic chemiluminescence of luminol decreased in the presence of protein. The apparatus consisted of only a luminol solution line equipped with an ultrasonic irradiation bath and a cobalt(II) catalyst solution line equipped with a sample inlet. Under optimum conditions, similar calibration curves were obtained for bovine serum albumin, bovine serum γ-globulin, human serum albumin, and human serum γ-globulin. According to the present method, these proteins could be determined in the concentration range 5.0×10−6–1.0×10−1 g dm−3, with a detection limit of 200 pg (injected sample volume 40 mm3, S/N=2) and a coefficient of variation of 2.9% (n=8) at a rate of about 60 samples per hour.
Ligand-Substitution Reaction Kinetics of Tris(8-quinolinolato)- and Bis(2-methyl-8-quinolinolato)(8-quinolinolato)aluminum(III) Complexes with Ethylenediamine-N,N,N′,N′-tetraacetic Acid
Authors: Horihata Tomonori , Okamoto Ken-ichi , Hidaka Jinsai , Einaga Hisahiko
Published: July 2006

Ligand-substitution reactions of [Al(hq)3] and [Al(hq)(mhq)2] (H(m)hq: (2-methyl-)8-quinolinol) with H4edta have been studied at 25 °C and 1.0 mol dm−3 NaCl by means of the stopped-flow spectrophotometric method. Three concurrent reaction pathways, a dissociative activation one and two parallel associative activation ones, to which H2edta2− and Hedta3− contribute, are elucidated.
Chemistry of Germanium Atoms. IV. A New Method for Preparation of Organogermanium Halides by Co-condensation of Germanium Vapor with Tetrahydrofuran
Authors: Mochida Kunio , Nakai Y\={u}ko , Shiota Shigeru
Published: July 2006

Germanium vapor (atom) when co-condensated with THF at 77 K was found to be reactive toward organic halides. Several organogermanium halides were prepared by the addition of organic halides to the resultant germanium atom-THF slurry at ambient temperatures.
Facile Photorearrangement of Some Crowded Azoxyarenes via Two Concurrent Pathways
Authors: Okubo Masao , Hyakutake Hayato , Taniguchi Naoki
Published: July 2006

Naphthalene-1-ONN-azoxybenzenes and some unsymmetrically ortho-substituted ONN- and NNO-azoxybenzenes were prepared, and their photochemical behavior in ethanol was compared. The crowded azoxyarenes tend to undergo a facile Wallach rearrangement via the known azoxy-ortho oxygen mirgation and a concurrent pathway involving ONN–NNO isomerization. The relative contribution of the two pathways was affected by substituents.
Novel Synthesis of Isoflavones by the Palladium-Catalyzed Cross-Coupling Reaction of 3-Bromochromones with Arylboronic Acids or Its Esters
Authors: Hoshino Yukio , Miyaura Norio , Suzuki Akira
Published: July 2006

The synthesis of isoflavone derivatives by means of palladium-catalyzed cross-coupling reaction between 3-bromochromones and arylboronic acids or its butyl esters is described.
Determination of a Small Amount of a Biological Constituent by the Use of Chemiluminescence. XII. Highly Sensitive Immunoaffinity Chromatography
Authors: Hara Tadashi , Tsukagoshi Kazuhiko , Arai Akihiro , Iharada Takeshi
Published: July 2006

Highly sensitive immunoaffinity chromatography was established by combining a micro-bore affinity column with a chemiluminescence detector for protein monitored by a flow-injection method using a 1,10-phenanthroline–hydrogen peroxide–copper(II) system. After having optimized the bed volume of a column, the flow rate of a buffer solution which was used for an immune reaction, and the time necessary for an immune reaction in a column, human serum albumin in the range of 3×10−4–1×10−1 g dm−3 could be determined, with the detection limit of 15 ng as the injected amount. Human serum γ-globulin and bovine serum γ-globulin showed somewhat nonspecific adsorption onto an affinity column with values of 0.16 and 0.14 based on the specific adsorption 1.00 of human serum albumin onto a column, whereas bovine serum albumin, bovine serum α-globulin, and ovalbumin showed no nonspecific adsorption.
Ruthenium Complex-Catalyzed Silylation of Olefins. Selective Synthesis of Allylsilanes
Authors: Hori Yoji , Mitsudo Take-aki , Watanabe Yoshihisa
Published: July 2006

(1-2; 5-6-η-Cyclooctadiene)(1-6-η-cyclooctatriene)ruthenium catalyzes the silylation of olefins at 60–140 °C to give allylsilanes with good selectivity in high yields. The reactions of trialkylsilane with 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene give the same product, 3-methyl-1-trialkylsilyl-2-butene. Silylation of ethyl (E)-2-butenoate gives ethyl (E)-4-trialkylsilyl-2-butenoate in high yield.
A Tin-Mediated One-Step Synthesis of (+)-Dicrotaline, an 11-Membered Dilactonic Pyrrolizidine Alkaloid
Authors: Niwa Haruki , Okamoto Osamu , Ishiwata Hiroyuki , Kuroda Akio , Uosaki Youichi , Yamada Kiyoyuki
Published: July 2006

A new synthesis of (+)-dicrotaline (1), an 11-membered dilactonic pyrrolizidine alkaloid of retronecine (6) type has been achieved in one step by utilizing a tinmediated lactonization process.
A Peculiar Conformation of Normal-Chain Dicarboxylic Acid Salts in Aqueous Solutions
Authors: Fukushima Kunio , Adachi Koichi , Watanabe Kiyohisa
Published: July 2006

The Raman spectra of adipic acid, pimelic acid, and their salts were observed for various states. The spectra of the acids in aqueous sodium hydroxide solutions were found to be very different from those of the acids in organic solvents. The difference was interpreted, on the basis of normal vibration calculations, as being due to the helix formation of molecules in the former solutions. This tendency toward helical coiling is consistent with the same tendency found for the salts of azelaic acid and suberic acid in our previous study.
The Temperature Dependence of the Conductivities and Ion-Association Constants of Potassium Nitrate and Potassium Perchlorate in Water
Authors: Yokoyama Haruhiko , Ohta Tomoko
Published: July 2006

The electric conductivities of potassium nitrate and potassium perchlorate in water have been measured at eleven temperatures from 0 to 50 °C and analyzed in order to obtain the ion-association constants and the limiting molar conductivities of these salts. It was found that the observed ion-association constants have a minimum value at 30 °C for KNO3 and at 36 °C for KClO4. Such a characteristic temperature dependence was considered to be due to the presence of specific short-range interactions within contact ion pairs, although the weak hydration of the ions seemed to help the formation of the contact ion pairs. The experimental standard enthalpies and entropies of ion association were discussed in comparison with the theoretical ones. The limiting molar conductivities of NO3− and ClO4− at each temperature were also evaluated and expressed as cubic equations of the temperature.
Monolayers of Triple Long-Chain Salts on the Concentrated Sodium Chloride Solution
Authors: Shibata Osamu , Kaneshina Shoji , Matuura Ryohei
Published: July 2006

The surface pressure–area (π–A) curves for monolayers of four kinds of cation-anion triple long-chain salts [dialkyldimethylammonium alkanesulfonates] on the aqueous solution of 4.4 M NaCl were measured at various temperatures by the Langmuir method. Some π–A curves of these salts showed two transition points. Judging from the apparent molar entropy change on the transition, the first was assigned to the transition from the expanded state (E phase) to the condensed state (C-I phase) and the second to the transition from the C-I phase to another condensed state (C-II phase). In this paper, another condensed phase (C-I′) was newly observed over a certain temperature range on the phase diagram, which is the intermediate phase between the C-I phase and the C-II phase. There exist two triple points on the phase diagram at which three phases (i.e., E, C-I, and C-I′, and C-I, C-I′, and C-II) coexist. From the apparent molar entropy change, limiting area, compressibility, and phase diagram, the orientation of (2–1) long-chain salts in the monolayer state was assumed.
A Facile Synthesis of 3-Hydroxymethyl- and 3-Formylindoles from o-Nitrotoluene
Authors: Tanaka Hideo , Murakami Yasuo , Okamoto Koichi , Aizawa Takao , Torii Sigeru
Published: July 2006

A synthesis of 3-hydroxymethyl- and 3-formylindoles has been performed by manipulation of the side chain of 3-hydroxymethylindoline derived from o-nitrotoluene. Electro-reductive cyclization of 2-(2-nitro-phenyl)-1,3-bis(methylsulfonyloxy)propane to 3-(benzyloxymethyl)indole, is also discussed.
Mössbauer Spectroscopic Characterization of Iron Supported on Y Type Zeolites after Sulfiding
Authors: Hidaka Setsuo , Iino Akira , Nita Kenji , Morinaga Kenji , Yamazoe Noboru
Published: July 2006

Iron supported on zeolite catalysts, prepared by treating NH4Y with aqueous solutions containing Fe3+ or Fe2+ ions followed by calcination in air, were subjected to Mössbauer spectroscopic investigations before and after sulfiding treatments to elucidate the states and properties of Fe species supported. At least three types of Fe3+ species could be distinguished in the prepared samples. The first Fe3+ species were those located at the cation-exchange sites of zeolite. This type was reduced easily to Fe2+ species with the H2S treatment, but was resistant to aggregation to form Fe1−xS. The second Fe3+ species were those which had precipitated on the surface of zeolites as hydroxides. These were sulfided to crystalline Fe1−xS after H2S treatment. Finally, the third Fe3+ species were those which were quite resistant to both reduction to Fe2+ and sulfiding to Fe1−xS. These species were preferentially supported under the conditions where dealumination from zeolite framework took place simultaneously. Thus it was speculated that these species were bonded to zeolite framework to be stabilized. The distribution of the three Fe3+ species were quite different depending on the sample preparation. Comparison with the catalytic data clearly indicated that the third Fe3+ species acted as highly active sites for the toluene disproportionation reaction in the presence of H2S.
Diastereoselective Hydrogenation of Methyl 2-[α-(Methoxycarbonylamino)benzyl]acrylate Catalyzed by Ru(II) or Rh(I) Complexes
Authors: Yamamoto Keiji , Takagi Masatoshi , Tsuji Jiro
Published: July 2006

The title compound was prepared and hydrogenated by using a Ru(II)- or Rh(I)-phosphine catalyst precursor with excellent anti-selectivity, the results indicating that a ligating group, NHCO2Me, may direct the addition of hydrogen to an olefinic diastereoface proximate to this group which binds the catalyst.
XANES of Aqua Complexes of 3d Transition Metal in Solid Solution
Authors: Miyanaga Takafumi , Watanabe Iwao , Ikeda Shigero , Tashiro Kouji , Fujiwara Takashi
Published: July 2006

A characteristic second peak appears at about 10 eV from a main peak in the XANES (X-ray Absorption Near Edge Structure) spectrum of aqueous 3d transition metal complex of divalent state. This second peak is prominent in solid samples. The peak intensity depends on the kind of central metal or counter anion in solid. Theoretical calculations based on the full multiple scattering formalism provide the information regarding the origin and property of the second peak in XANES. The second peak can be reproduced by the multiple scattering calculation considering only six first coordinating oxygen atoms. The intensity and the position of the peak vary with the charge on the first coordinating oxygen atoms which is affected by the ions or solvent molecules contacting with the metal complex.
A Novel Chiral Stationary Phase for Optical Resolution of Amino Acids and Their Derivatives by Ligand-Exchange High-Performance Liquid Chromatography
Authors: Saigo Kazuhiko , Yuki Yoichi , Kimoto Hiroki , Nishida Toru , Hasegawa Masaki
Published: July 2006

A novel chiral stationary phase, [(1R,2S)-2-hydroxy-1-methyl-2-phenylethylamino]acetic acid, was prepared from (−)-norephedrine, and its sodium salt was bound to silica gel pretreated with [3-(glycidyloxy)propyl]trimethoxysilane. The chiral stationary phase was found to be effective for the optical resolution of amino acids and their derivatives by ligand-exchange high-performance liquid chromatography using aq copper(II) sulfate solution as an eluent.
Synthetic Photochemistry. XLII. Total Synthesis of Cycloaraneosene, a Fundamental Hydrocarbon of 5–8–5-Membered Tricydic Diterpenoid from Sordaria araneosa
Authors: Kato Nobuo , Tanaka Shinya , Takeshita Hitoshi
Published: July 2006

A 5–8–5-membered tricyclic diterpene, cycloaraneosene, has been totally synthesized via a stereoselective condensation of two units of optically active iridoids, a Cope rearrangement, a chemical reduction of the tetrasubstituted double bond, and the formation of an eight-membered ring. The proposed structure of natural hydroxycycloaraneosene should be revised to 8β-hydroxycycloaraneosene, judging from the NMR spectral data.
Regio- and Stereoselective Ring Opening of ω-Alkenyllactones Using Organocopper Reagents
Authors: Kawashima Masatoshi , Sato Toshio , Fujisawa Tamotsu
Published: July 2006

New synthetic methods are described for the preparation of (E)-3-, (E)-4-, and (E)-5-alkenoic acids by the regio- and stereoselective ring opening of β, γ, and δ-lactones with unsaturated substituents at the ω-position using organocopper reagents such as halomagnesium diorganocuprates or Grignard reagents in the presence of copper(I) iodide. Both the organocopper reagents with primary, secondary, tertiary alkyl, and phenyl groups gave the corresponding carbon homologated alkenoic acids in good yields. Alkadienoic acids were also obtained in good yields by the reactions of ω-alkenyllactones with divinyl- and diallylcuprates. Utilizing the ring opening of β-isopropenyl-β-propiolactone, homoterpenoid carboxylic acids were easily obtained in good yields. The ring opening of β-(1-chlorovinyl)-β-propiolactone afforded 4-chloro-3-alkenoic acids which were easily transformed to 4-oxoalkanoic acids and 4-oxo-2-alkenoic acids.
Apparent Molal Volumes of Urea Derivatives in Water–Methanol Mixtures
Authors: Mizutani Kiyoshi , Yasuda Motoo
Published: July 2006

Apparent molal volumes (φv) at 25 °C have been obtained for the following urea derivatives in water–methanol mixtures from measurements of the density using an Anton Paar digital densimeter: urea (U), methylurea (MU), ethylurea (EU), 1,1-dimethylurea (1,1-DMU), 1,3-dimethylurea (1,3-DMU), 1,1-diethylurea (1,1-DEU), and 1,3-diethylurea (1,3-DEU). The limiting values φv° were calculated by linear extrapolation using the least-squares method. A plot of φv° vs. X2, the mole fraction of methanol, showed a minimum for each alkylurea studied at low methanol concentrations (X2\simeq0.1), but none for unsubstituted urea: the more alkyl-substituted the urea was, the sharper the minimum. Inspection of the data shows that the assumption of independent solvation on both sides of the urea molecules also holds to a good approximation to the apparent molal volumes both in the pure solvents and in the mixtures.
Facile Conversion of Aldehydes into 1-Substituted 2-Chloro-3,3-difluoro-2-propen-1-ols with 1,1-Dibromo-1-chloro-2,2,2-trifluoroethane/Magnesium Reagent
Authors: Fujita Makoto , Hiyama Tamejiro
Published: July 2006

Aldehydes RCHO are converted in excellent yields into chlorodifluoroallyl alcohols RCH(OH)CCl=CF2 upon treatment with CClBr2CF3 and magnesium in tetrahydrofuran at 0 °C.
Helix Formation of Poly(l-ornithine) in Decyl and Dodecyl Sulfate Solutions
Authors: Takeda Kunio , Yamamoto Kazuo
Published: July 2006

Structural changes in poly(l-ornithine)[(Orn)n] were studied in solutions of sodium decyl sulfate (NaDecSO4) by the curve-fitting method of circular dichroism. In the NaDecSO4 concentration range from 4 to 9 mmol dm−3, only the β-structure was found. Below and above this concentration range, however, the α-helical structure was formed slightly, its fraction being less than 20%. The addition of 1-octanol enhanced the helix formation in the (Orn)n–NaDecSO4 complex.
Electrical Properties of the Organic Conductor, (BEDT-TTF)3(ClO4)2
Authors: Imaeda Kenichi , Enoki Toshiaki , Saito Gunzi , Inokuchi Hiroo
Published: July 2006

Electrical conductivity and thermoelectric power have been measured for (BEDT-TTF)3(ClO4)2. The electrical conduction is two-dimensional in the be plane. The metal–insulator transition temperature is lowered by pressure at a rate of −8 K kbar−1. The negligible thermopower at high-temperatures indicates that (BEDT-TTF)3(ClO4)2 is the system with large on-site Coulomb repulsion.
Photosensitized Reduction of Methylviologen through the Energy Transfer from Triplet Dyes to 9-Anthracenecarboxylate Anion
Authors: Usui Yoshiharu , Sasaki Yoshimi , Ishii Yukie , Tokumaru Katsumi
Published: July 2006

The reaction mechanism for photosensitized reduction of methylviologen, MV2+ through the triplet–triplet energy transfer from organic dyes to 9-anthracenecarboxylate, AC− was investigated. From the kinetic analysis on MV\underset.+ formation, it was estimated that both efficiencies of the energy transfer and of the electron transfer from 3AC− to MV2+ were close to unity.
The Second Dissociation Constant of Sulfuric Acid at Elevated Temperatures from Potentiometric Measurements
Authors: Matsushima Yoshiyuki , Okuwaki Akitsugu
Published: July 2006

The second dissociation constant of sulfuric acid in 1 m KCl media has been determined from 25 to 200 °C using Debye–Hückel equation from the data on the electromotive force of a hydrogen ion-concentration cell. The thermodynamic values for the HSO4−=H++SO42− reaction and the KSO4− ion-pair association constant are also presented.
Synthesis of Mixed Trialkyl Phosphates: Oxidative Phosphorylation of Alcohols with Dialkyl Phosphonates in the Presence of Copper(II) Chloride
Authors: Okamoto Yoshiki , Kusano Tetuya , Takamuku Setsuo
Published: July 2006

Mixed trialkyl phosphates were synthesized by oxidative phosphorylation of alcohols with dialkyl phosphonates and oxygen in the presence of copper(II) chloride in fairly good yields.
One-Step Synthesis of 1,4-Diketones by Nucleophilic Reaction to Tricarbonyl Complexes of α,β-Unsaturated Ketones
Authors: Kitahara Haruo , Tozawa Yasuyuki , Fujita Seikou , Tajiri Akio , Morita Noboru , Asao Toyonobu
Published: July 2006

Tricarbonyliron complexes of 3-buten-2-one, 3-penten-2-one, and 4-phenyl-3-buten-2-one reacted with organolithium and Grignard reagents to afford 1,4-diketones in one step, some of the products are amenable to convertion to natural products.
Solid-Phase Synthesis of C-Terminal Hexapeptide Analogs of Substance P
Authors: Sofuku Shosuke , Ishikawa Atsushi , Muramatsu Ichiro , Shibata Kensuke
Published: July 2006

C-Terminal hexapeptide analogs of substance P (SP) were synthesized by a solid-phase method. These analogs, [Dab6]-SP(6-11), [Orn6]-SP(6-11), and [Lys6]-SP(6-11), showed a contractile activity on an isolated guinea-pig ilum.
A Facile Method for the Preparation of γ-Alkenyl-γ-butyrolactones
Authors: Kawashima Masatoshi , Fujisawa Tamotsu
Published: July 2006

Methyl substituted γ-alkenyl-γ-butyrolactones were prepared from easily available α,β-unsaturated aldehydes such as acrylaldehyde, methacrylaldehyde, crotonaldehyde, and 3-methyl-2-butenal.
Time-Dependent Metastable Fragmentations. The \dotCH2OH Loss from Methyl Acetate Ions
Authors: Arakawa Ryuichi
Published: July 2006

The metastable ion intensity for the loss of \dotCH2OH from ionized methyl acetate has been measured as a function of the ion-source residence time up to 100 μs by means of the ion-trapping technique. The decay of the metastable ion intensity was adequately interpreted by the use of a prior isomerization mechanism on the basis of RRKM calculations. It was suggested that the intermediate precursor for the generation of CH3CO+ and \dotCH2OH from ionized methyl acetate is not a hydrogen-bridged complex structure, CH3CO–H–OCH2+·, but a distonic ion structure, CH3\overset+C(OH)O\dotCH2.
Electronic Structure of Poly(dimethylsilane) and Polysilane Studied by XPS, UPS, and Band Calculation
Authors: Seki Kazuhiko , Mori Takehiko , Inokuchi Hiroo , Murano Kentaro
Published: July 2006

The valence electronic structures of poly(dimethylsilane)(PDMS) (Si(CH3)2)n and polysilane (SiH2)n were studied. PDMS was experimentally studied by X-ray photoelectron spectroscopy (XPS) and UV photoelectron spectroscopy (UPS), and band calculations were performed for both compounds. The observed spectral features and calculated band structures were assigned and discussed through a comparison with theoretical and experimental results for oligomers and other polymers. These analyses have demonstrated how the electronic structures of these compounds are correlated through factors such as (i) change in the chain length, (ii) methylation, and (iii) the substitution of Si by C. PDMS has a small ionization energy (5.9 eV) almost as low as that of poly(p-phenylene) (5.6 eV). This small value comes from the combined contribution from the small electronegativity of silicon, σ-conjugation, and the inductive effect of methyl groups. The small ionization energy and large σ-conjugation explain the reported high conductivity of PDMS and its derivatives upon acceptor doping.
Inversion of Stereoselectivity by Hydrophobic Interligand Interactions. Preparation, Structure, and Stereoselectivity of {N,N′-Ethylenebis(1,1,1-trifluoro-4-amino-2-pentanonato)}(l-amino acidato)cobalt(III)
Authors: Fujii Yuki , Shinohara Homare , Mikuriya Masahiro , Kida Shigeo , Konishi Yoshie
Published: July 2006

Ternary cobalt(III) complexes with a general formula β2-[Co(tfac2en)(l-aa)], where tfac2en is the titled Schiff base ligand and l-aa denotes l-ala, l-leu, l-phe, l-tyr, and l-trp, were synthesized and separated into two diastereoisomers. On the bases of X-ray crystal analysis of the l-phe complex, CD, and 1H and 19F NMR spectra, the structure of (−)435- and (+)435-isomers was determined to be Λ- and Δ-cis-β2-forms, respectively, and preferred conformation of the coordinated l-amino acidates was assummed to be h-form in solution. All the complexes showed stereoselectivity for the Λ-isomer in acetone and methanol, but the selectivity decreased or reversed with addition of water. The solvent-dependent stereoselectivity was explained in terms of steric repulsion and hydrophobic interligand interactions between CF3 group of tfac2en and side chain of l-aa.
Synthesis and Cation-Complexing Ability of Ferrocene or Ruthenocene Functionalized Crown Ethers Possessing 2,6-Pyridino Moieties
Authors: Izumi Taeko , Murakami Satoshi , Kasahara Akira
Published: July 2006

Keto crown ethers that contain ferrocene or ruthenocene and 2,6-disubstituted pyridine unit as part of the major ring have been reported. These keto crown ethers were synthesized by a reaction of 1,1′-metallocenedicarbonyl dichloride (ferrocene or ruthenocene) with 2,6-bis[ω-hydroxyoligo(oxyethylene)-α-ylmethyl]pyridine by using a high-dilution method. Their complexing ability with metal cations was measured by a solvent-extraction method, and was found to be poor with alkali metal cations but excellent with Ag+, In3+, and Zr4+ cations.
Synthesis, Structure, and Hypochromism of Pyrimidinopurinophanes
Authors: Doyama Kazuo , Higashii Takayuki , Seyama Fumio , Sakata Yoshiteru , Misumi Soichi
Published: July 2006

Seventeen pyrimidinopurinophanes in which a pyrimidine and a purine ring are fixed with different mode of stacking were prepared. The synthesis was carried out by stepwise introduction of two bridging chains. In the final ring closure reaction, two isomers, i.e., isomers bridged at 9-position of a purine ring and those having the bridge at 7-position of a purine ring were obtained. The structures of the isomers were determined on the basis of 1H NMR, IR, and UV spectra and X-ray analysis. In 1H NMR spectra the bridge protons of the pyrimidinopurinophanes show complex multiplets, in contrast to the first order splittings in singly bridged reference compounds. This shows clearly the fixation of the conformations of the present cyclic compounds at room temperature. All of the pyrimidinopurinophanes show relatively large hypochromism (H) values. Even the compounds 2a–2d, 4, and 6 where the two base rings are not stacked in parallel, but inclined with the dihedral angle of around 50°, show H values of 10–20%. The H values did not change among the compounds 1c, 1e–1g, and 3 which have similar parallel-stacking structures of the two base rings. The results are well explained by the simplified equation of Ts′o et al.
On the Mechanism of Reductive Cleavage of the Carbon–Nitrogen Bond of Aliphatic Nitro Compounds with Tributyltin Hydride
Authors: Kamimura Akio , Ono Noboru
Published: July 2006

Denitrohydrogenation reaction of aliphatic nitro compounds with tributyltin hydride (Bu3SnH) is accelerated in the presence of radical initiators. ESR and electrochemical measurements reveal that the reductive cleavage of the carbon–nitrogen bond proceeds not via anion radicals of nitro compounds such as SRN1 reaction but via β-scission of (tributylstannyloxy)nitroxyl radicals. The relative reactivities of tin radicals toward substituted α-nitrocumenes, α-nitroethylbenzenes, and α-nitropropiophenones exhibits excellent Hammett correlations with positive ρ values. This tendency has also been found in the reaction of benzyl halides with tin radical. These results suggest that the carbon–nitrogen bond breaking from nitroxyl radical intermediates should take place in rate-determining step for the reaction.
Studies on Dielectric Permittivities, Refractive Indices for 1,1′-Bicyclohexyl Liquid Crystals in the Nematic and Isotropic Phases
Authors: Sen Sushmita , Kali Krishnakoli , Roy Subir K
Published: July 2006

The dielectric permittivities ε|| and ε⊥ and the refractive indices ne, no of five 4-cyano-4′-alkyl-1,1′-bicyclohexyls (CCH 2, CCH 3, CCH 4, CCH 5, CCH 7 where 2, 3, 4, 5, 7 means ethyl, propyl, butyl, pentyl, heptyl respectively) have been measured at different temperatures in the nematic and isotropic phases. The orientational order parameter from the refractive indices data, calculated from (1) Vuks’ method and (2) Neugebauer’s method were in good agreement. At any reduced temperature, the order parameter for CCH 2 is largest and that of CCH 7 is smallest and those for the others are in between them. Unlike for cyanobiphenyls or cyclohexylbenzenes, the dielectric permittivity ε|| is obtained for \overset→E⊥\overset→H and ε⊥ for E||H, where \overset→E is the electric and \overset→H is the magnetic field, and has been explained as due to these molecules having negative diamagnetic anisotropy. The dielectric anisotropy, Δε and optical anisotropy Δn for all the CCH’s is much less than that of the corresponding CB or PCH molecules. All the CCH’s show pretransitional permittivity just above the transition temperature TNI.
Conductivity of Iron(II) Sulfate in Aqueous Solution at Various Temperatures
Authors: Kubota Eiji , Mochizuki Yoshiaki , Yokoi Masatoki
Published: July 2006

The molar conductivity of iron(II) sulfate, FeSO4, in water was measured in the temperature range 10–35°C. Data were analyzed by the Quint–Viallard equation, and the resulting ion association constant, KA, was applied to the Bjerrum equation to determine the contact ion size, RB. The limiting ionic molar conductivity of iron(II) at 25°C is λ0(1⁄2Fe2+)=53.8 S cm2 mol−1. Thermodynamic properties of ion association reactions are ΔG298°=−13.7 kJ mol−1, ΔH°=9.7 kJ mol−1, and ΔS298°=78.0 J K−1 mol−1.
The Photochemical Debromination of Bromocyclopropane in the Presence of Amine
Authors: Tomioka Hideo , Inoue Osamu
Published: July 2006

The irradiation of bromoarylcyclopropanes (1) in the presence of tertiary amine resulted in the formation of the debrominated cyclopropanes as a mixture of geometrical isomers, whose ratios were essentially similar regardless of the stereochemistry of the bromide. The reactions were not, however, observed in the absence of amine. The results are interpreted as indicating that the reactions proceed through an initial single-electron transfer to the excited 1, followed by debromination and hydrogen-abstraction.
Chemistry of Germanium Atoms. V. Deoxygenation of Carbonyl Compounds by Germanium Vapor (Atom)
Authors: Mochida Kunio , Mizuno Yasuhiro
Published: July 2006

The co-condensation of thermally evaporated germanium vapor with carbonyl compounds was found to yield olefins and germanium monoxide.
A Michael Reaction Product of Cyclohexylidenemalononitrile
Authors: Nakano Yoshiharu , Yokota Hiroaki , Igarashi Minoru , Sato Shoichi
Published: July 2006

Cyclohexylidenemalononitriles dimerize and cyclize to give 3-amino-2,4-dicyano-2-[imino(methoxy)methyl]spiro[bicyclo[4,4,0]deca-3,5-diene-1,1′-cyclohexane] (3). The crystal structure of 3 was determined by an X-ray diffraction method.
Fries Rearrangement in Calixarene Esters: A New Entry for the Synthesis of p-Substituted Calixarenes
Authors: Arimura Takashi , Shinkai Seiji , Matsuda Tsutomu , Hirata Yoshimi , Satoh Hiroshi , Manabe Osamu
Published: July 2006

The Fries rearrangement was found to be a convenient method to synthesize p-acylcalixarenes from O-acylcalixarenes, the yields being relatively good (29–34%) as a synthetic method for p-substituted calixarenes.
Electronic and ESR Spectral Studies of a Series of Phosphine and Phosphite Adducts with Cobaloxime Analog
Authors: Mita Keisuke , Hotta Kazuhiko , Takui Takeji
Published: July 2006

Electronic and ESR spectra were measured for solutions of Co(dmgBF2)2 in the presence of PX3, where Co(dmgBF2)2 is a BF2 capped species of bis(dimethylglyoximato)cobalt(II) (Co(Hdmg)2) and PX3 is PBu3, PPh3, P(OEt)3, or P(OPh3)3. 31P hyperfine splittings of their ESR spectra demonstrated that Co(dmgBF2)2 forms only 1 : 1 adducts with PX3. The visible absorption spectrum of the dichloromethane solution of Co(dmgBF2)2 showed an absorption band at 444 nm at 20°C. Upon PX3 being added to the solution, the band shifted to a longer wavelength; the band shift increased with increasing the electron-donating ability of PX3.
Configurational Stability of Optically Active Selenoxides; Racemization via Achiral Hydrate
Authors: Shimizu Toshio , Kobayashi Michio , Kamigata Nobumasa
Published: July 2006

Configurational stabilities of optically active diaryl selenoxides are examined under several conditions such as acidic, basic, or in the presence of water. It is found that the diaryl selenoxide which has two hindered t-butyl groups on the ortho positions is relatively stable toward racemization even under acidic conditions. Mechanism of racemization is ascertained to be via formation of the achiral hydrate (R–Se(OH)2–R′) by the observation of oxygen exchange on the selenium atom.
A Short-Step Synthetic Approach to Eudesmane Skeleton. A Synthesis of (±)-β-Eudesmol and Related Eudesmane Sesquiterpenes
Authors: Kawamata Takeshi , Harimaya Kenzo , Inayama Seiichi
Published: July 2006

The formal total syntheses of (±)-β-eudesmol and its related sesquiterpenes such as cryptomeridiol and neointermediol were accomplished by an efficient method using aldol cyclization as the key step starting from the known 3-vinyl-2-cyclohexen-1-one.
A New and Simple Route to 3-Arylthiophenes
Authors: Sone Tyo , Inoue Manabu , Sato Kazuaki
Published: July 2006

3-Arylthiophenes were prepared from 2,5-dichlorothiophene in two steps. 2,5-Dichlorothiophene reacted regioselectively with various aromatic compounds in the presence of AlCl3 under mild conditions to give 4-aryl-2-chlorothiophenes. The latter compounds were easily converted to the corresponding 3-arylthiophenes by catalytic dechlorination in good yields.
A Reinvestigation of a Sensitized Photochemical Cycloaddition of Coumarin with Cyclopentene
Authors: Suginome Hiroshi , Kobayashi Kazuhiro
Published: July 2006

A reinvestigation of a sensitized photochemical cycloaddition of coumarin with cyclopentene reported by Hanifin and Cohen indicated that the cycloaddition gives a sterically disfavored cis-cisoid-cis adduct (18%) together with a cis-transoid-cis adduct (25%) and a head-to-head coumarin dimer with a cis-transoid-cis disposition. The two adducts behaved differently in hydrolysis and recyclization.
New Applications of Crown Ethers. IX. Crystal Structure of KSCN Complex of N-Heptylmonoaza-18-crown-6, and Conformational Features of the Pivot Nitrogen
Authors: He Gong-Xin , Kikukawa Kiyoshi , Nishiyama Nobuaki , Ohe Hiroshi , Matsuda Tsutomu
Published: July 2006

Vertical arrangement of the alkyl side arm in the crystal structure of KSCN complex of N-heptylmonoaza-18-crown-6 is well-consonant with the effective side-arm participation in N-pivot lariat ether complexes and supports the lack of ‘biscrown effect’ for bis(monoaza-18-crown-6)s.
The Thermal Decomposition and Hydrolysis of Calcium Carbamoyl Phosphate
Authors: Shimasaki Choichiro , Suzuki Hiroki
Published: July 2006

Calcium carbamoyl phosphate (1) was prepared by adding an aqueous calcium chloride solution to a reaction solution of KH2PO4 with KOCN. 1 was unstable at room temprature. 1 was dehydrated to make anhydrous salt and thermally decomposed to liberate ammonia, cyanic acid, and carbon dioxide, finally resulting in the formation of calcium pyrophosphate in air. The apparent activation energies for the three endothermic peaks of the DTA curve were estimated to be 50.0, 83.9, and 148.3 kJ mol−1 respectively. The hydrolysis of 1 in an aqueous solution apparently obeyed the first-order kinetics. The activation parameters for the hydrolysis of 1 were evaluated by using the 31P NMR spectra of 1 with the lapse of the reaction time. The activation energy was 92.2 kJ mol−1; the activation enthalpy, 89.7 kJ mol−1, and the activation entropy, −6.3 e.u.
New Thiazolo[5,4-d]pyrimidines with Molluscicidal Properties
Authors: El-Bayouki Khairy A M , Basyouni W M
Published: July 2006

Ethyl chloroformate/DMF mixture is used as a reagent for the facile ring closure of 5-amino-2-(ethylthio)thiazole-4-carboxamide (1a) to afford an excellent yield of 2-ethylthiothiazolo[5,4-d]pyrimidin-7(6H)-one (3). The action of phosphoryl chloride on the latter product gave its 7-chloro derivative (4). The corresponding 7-(dicyanomethyl) (5a), 7-[cyano(ethoxycarbonyl)methyl] (5b), and 7-(substituted amino)derivatives (6a–j) are synthesized from reactions of malononitrile, ethyl cyanoacetate, and primary amines, respectively, with compound 4. Most of the obtained products have been screened for activity against the intermediate host of schistosomiasis, B. alexandrina snails.
Theoretical Treatment of Solvent Effects on the Frequency Shifts of Fluorescence Spectra
Authors: Abe Takehiro
Published: July 2006

A theoretical expression for the solvent fluorescence spectral shifts of a neutral solute molecule has been developed by following the same treatment as in Abe’s expression for solvent absorption spectral shifts (Bull. Chem. Soc. Jpn., 54, 327 (1981); 58, 3415 (1985)). Compared with all previous applicable expressions being applied to only polar solute molecules, the present expression has the advantage that it can be applied to not only the polar solute molecules but also nonpolar solute molecules. The polarizabilities of the ground and excited states concerning fluorescence are treated as being different from the corresponding values concerning absorption. Applications to nonpolar solute molecules are successfully presented.
Crystal and Molecular Structure of Double Macrocyclic Inclusion Complexes, γ-Cyclodextrin·12-Crown-4·NaCl, a Model for the Transport of Ions through Membranes
Authors: Kamitori Shigehiro , Hirotsu Ken , Higuchi Taiichi
Published: July 2006

The crystal structure of a γ-cyclodextrin·12-crown-4·NaCl (3 : 3 : 1) inclusion complex was determined by an X-ray method to be space group P4212, a=b=23.816(3) Å, c=23.072(3) Å. The inclusion complex has a C4 symmetry, and the cation, Na+, is coordinated by two 12-crown-4 molecules in a hydrophobic channel formed by tail-to-tail oriented two γ-cyclodextrin molecules.
Pressure and Temperature Effects on Octahedral–Tetrahedral Equilibria in 4-Methylpyridine and 2-Methylpyridine Solutions of Some Cobalt(II) Halides
Authors: Kojima Kazuo
Published: July 2006

The visible absorption spectra of CoX2 (X=Cl, Br) in solutions of both 4-methylpyridine (4-Me-py) and 2-methylpyridine (2-Me-py) have been measured in the pressure range of 1 bar −3 kbar at room temperature, and in the temperature range of ≈6–≈75 °C at 1 bar. In the 4-Me-py solution system, the configuration equilibrium, [CoX2(4-Me-py)2] (tetrahedral) +2(4-Me-py)\ightleftarrows[CoX2(4-Me-py)4] (octahedral), was found to exist over the experimental pressure range. Increasing the pressure shifted the equilibrium toward the octahedral species side with volume changes of −26 cm3mol−1 for the chloro complex and −25 cm3mol−1 for the bromo complex at 1 bar. The above equilibrium held fairly well over the whole experimental temperature range for the chloro complex, but in the restricted temperature range for the bromo complex. Increasing the temperature tended to increase the formation of the tetrahedral species, the heats of reaction, being 53.3 kJ mol−1 and 62.6 kJ mol−1 for the chloro and bromo complexes, respectively. On the other hand, in the 2-Me-py solution system, increasing the pressure or temperature could hardly confirm the existence of the octahedral-tetrahedral configuration equilibrium. A charge-transfer band between the solvent molecule 2-Me-py and the free ion X− decreased in intensity with increasing temperature. The above results in the 4-Me-py and 2-Me-py systems were compared with those of the pyridine (py) and 3-methylpyridine (3-Me-py) systems mentioned in the literature.
Structure of Mixed Ligand Complex [Cu(pan)(phen)]BF4 with Special Reference to the Acceleration of the Ligand Substitution Reaction
Authors: Wada Hiroko , Shiro Motoo , Yuchi Akio , Nakagawa Genkichi
Published: July 2006

The crystal structures of [1-(2-pyridylazo)-2-naphtholato]copper(II) complexes, [Cu(pan)(phen)]BF4 as well as [Cu(pan)(H2O)]ClO4 and [Cu2(pan)2(H2O)3](BF4)2 have been determined. In these complexes pan− anion coordinates with copper(II) as a tridentate ligand and all complexes have square pyramidal geometry. In the mixed ligand complex [(Cu(pan)(phen)]BF4, 1,10-phenanthroline occupies the forth position in the basal plane and the apical site, thus the structure is fairly distorted. This distorted structure is responsible for the fast substitution of [Cu(pan)(phen)]+ complex with edta4−.