bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic Studies of Solvent and Pressure Effects on Thermochromic Behavior of 6-Nitrospiropyran
Authors: Sueishi Yoshimi , Ohcho Masanobu , Nishimura Norio
Published: July 2006

The thermal conversion of 6-nitrospiropyran from a merocyanine form to a spiro form was studied in various solvents and under high pressures. The rates of the thermal conversions were remarkably retarded in polar solvents, and a Kirkwood plot of the rate constants showed a large downward deviation as the solvent polarity increased. The rate constants (on a logarithmic scale) were linearly related to Kosower’s Z-values. The values of the activation volumes were positive and divided into two groups: ΔV≠≈10 cm3 mol−1 (in nonpolar solvents) and ΔV≠≈20 cm3 mol−1 (in polar solvents). These findings suggest that for the reaction in polar solvents, specific interactions are operating and that the thermal conversion proceeds via a transition state which is much less polar than the initial state.
NQR Study of Phase Transitions in SbCl3·(C6H5)2NH2+Cl− and 2SbCl3·C6H5OCH3
Authors: Ishihara Hideta , Okuda Tsutomu , Yamada Koji , Negita Hisao
Published: July 2006

The temperature dependence of 35Cl and 121,123Sb NQR frequencies was measured in SbCl3·(C6H5)2NH2+Cl− between 77 and 300 K. A phase transition takes place at 108 K and 35Cl NQR lines disappeared above about 275 K. Possible mechanisms of the phase transition and of the disappearance of 35Cl NQR lines were suggested. The phase transition in 2SbCl3·C6H5OCH3 was investigated by the NQR technique. The temperature dependence of the splitting of the 121Sb(ν1) NQR lines in the low-temperature phase gave a critical exponent of β=1⁄2 near the transition point Tc. A Zeeman-effect experiment revealed that the crystals in both low- and high-temperature phases were monoclinic.
Electrochemical Behavior of Dibutyltin(IV) Compounds and Their Determination at ppb Levels by Differential Pulse Anodic Stripping Voltammetry
Authors: Kitamura Hideki , Sugimae Akiyoshi , Nakamoto Masao
Published: July 2006

The electrochemical behavior of dibutyltin(IV) compounds (Bu2SnX2) (X=chloride, laurate (L), and 6-methylheptyl maleate (MHM)) in 50% (v/v) and 80% (v/v) ethanol–water media (apparent pH 7.3) containing 0.002% Triton X-100 has been investigated by polarography and cyclic voltammetry. It has been found that Bu2SnX2 gives a two-electron transfer step at about −0.8 V vs. SCE, which consists of very close two one-electron steps, and a two-electron step at about −1.4 V in both media. Over the potential range of either side of the first reduction wave, both Bu2SnX2 and their reduction products are significantly adsorbed on the surface of a mercury electrode in 50% (v/v) ethanol, but not in 80% (v/v) ethanol. The adsorbed reduction products are readily re-oxidized at the mercury electrode in 50% ethanol. The re-oxidation peak was successfully utilized for the determination of traces of Bu2SnCl2 by means of the differential pulse anodic stripping voltammetry (DPASV) over the concentration range of 3–50 ppb (μg dm−3) at the deposition time of 60 s. The DPASV behavior of Bu2SnX2 (X=chloride, L, MHM, and 1-dodecanethiolate) has been investigated in a 50% ethanol medium in detail. Further, a procedure has been developed for determining Bu2SnX2 in natural water down to ppb levels.
Hydroxylation of Aliphatic Compounds with m-Chloroperbenzoic Acid. Synthesis of Hydroxylated Vitamin K1 Analogues
Authors: Tori Motoo , Sono Masakazu , Asakawa Yoshinori
Published: July 2006

Pristane and 1,5,9,13-tetramethyltetradecyl acetate were treated with m-chloroperbenzoic acid in chloroform under reflux to afford hydroxylated derivatives, respectively. The products, 13- and 9-hydroxy-1,5,9,13-tetramethyltetradecyl acetates, were converted to hydroxylated vitamin K1 analogues via the corresponding hydroxyphytols.
Boron Trifluoride Etherate-catalyzed Backbone Rearrangement of 13β,18β-Epoxybaccharan-3β-yl Acetate. A Sequential Migration of Two Methyl Groups and a Hydride in Biogenetic Direction
Authors: Ohta Shinya , Tori Motoo , Suemura Koji , Irokawa Tomomi , Moriyama Yoshihiko , Tsuyuki Takahiko , Takahashi Takeyoshi , Itai Akiko , Iitaka Yoichi
Published: July 2006

13β,18β-Epoxybaccharan-3β-yl acetate was treated with boron trifluoride etherate in acetic anhydride to afford a complex mixture, in which a formation of backbone rearrangement products, D:C-friedobacchar-9(11)-en- and -7-en-3β-yl acetates together with 3β-acetoxy-D-friedo-13,18-secobacchar-13-en-18-ylidene diacetate was observed. The D:C-friedobacchar-9(11)-ene derivative is the first example of the backbone rearrangement product formed by a sequential migration of two methyl groups and a hydride towards the biogenetic direction in baccharene-shionene series.
Isomers of the (2,4-Pentanedionato)bis(N-phenylethylenediamine)cobalt(III) Ion
Authors: Ouyang Yue , Kojima Masaaki , Fujita Junnosuke
Published: July 2006

By reaction of [Co(acac)2(Ph-en)]+ (acac=2,4-pentanedionate ion, Ph-en=N-phenylethylenediamine) with Ph-en in methanol in the presence of active charcoal, three racemic pairs of diastereomers, Δ(SS) Λ(RR)-, Δ(SR)Λ(RS)-, and Δ(RR)Λ(SS)-trans(N-Ph,N-Ph)-[Co(acac)(Ph-en)2]2+ were obtained. The isomers epimerize in water, methanol, and ethanol to give an equilibrium mixture of the isomers.
Electron Transfer Initiated Replacement of Bromo and Methoxyl Groups with Aryliminodi-, Arylamino-, and Arylthiomagnesium Reagents
Authors: Okubo Masao , Nakagawa Yasuhiro , Yoshida Masatoshi , Yanase Hidenobu
Published: July 2006

The replacement of bromo and methoxyl groups of fluorenone, N-(9-fluorenylidene)aniline, and α-benzylideneacetophenone with ArSMgBr(S), ArNHMgBr(NH), and ArN(MgBr)2(N) were examined. The distribution of products obtained in the reactions with the reagents including ArMgBr(C) and ArOMgBr(O) were explained in terms of relative electron-donating abilities of reagents: C>S>NH>N>O.
Ultrasounds in Synthetic Reactions. III. Reduction of Organic Halides with Nickel(II) Chloride–Zinc–Water
Authors: Yamashita Junzo , Inoue Yoshio , Kondo Takashi , Hashimoto Harukichi
Published: July 2006

The reductive dehalogenation of aryl chlorides as well as other organic halides was facilitated with nickel(II) chloride–zinc–water in hexamethylphosphoric triamide irradiated with ultrasound.
Decarboxylative Photoaddition of 3-Butenoate Anion to 1-Methyl-2-phenyl-1-pyrrolinium Perchlorate via Electron-transfer Reaction
Authors: Kurauchi Yoshiaki , Ohga Kazuya , Nobuhara Hideo , Morita Shigeru
Published: July 2006

The photolysis of 1-methyl-2-phenyl-1-pyrrolinium perchlorate (1) with a 3-butenoate anion in an aqueous solution efficiently gives a 2-allylpyrrolidine adduct. Mechanistic studies demonstrate that the photo-reaction is induced by a one-electron transfer from 3-butenoate to the singlet excited-state of 1.
Preferred Conformation of 1-Phenyl-2-propanol. Ab initio and Molecular Mechanics Calculations with Geometry Optimization
Authors: Abe Kazuhisa , Hirota Minoru , Morokuma Keiji
Published: July 2006

The most stable conformation of 1-phenyl-2-propanol, optimized by ab initio and molecular mechanics (MM2) calculations, is a phenyl-methyl anti and phenyl-OH gauche conformation with an intramolecular OH-π hydrogen bond.
Synthesis of Ketazines from Dinitrogen Coordinated to Tungsten
Authors: Hidai Masanobu , Kurano Masa-aki , Mizobe Yasushi
Published: July 2006

When treated with a methanol/acetone mixture at 50 °C, the complex trans-[W(N2)2(PPh2Me)4] gives acetone azine in moderate yield, although the yield is slightly lower than that from cis-[W(N2)2(PMe2Ph)4]. Under UV irradiation, these dinitrogen complexes produce acetone azine even at room temperature.
Direct N-Allylation of Amides with 2-Allylisourea Catalyzed by Palladium(0)
Authors: Inoue Yoshio , Taguchi Masaaki , Hashimoto Harukichi
Published: July 2006

Direct N-allylation of amides catalyzed by palladium(0) complexes took place under neutral conditions by the use of 2-allylisourea as the allylating agent.
Gas Chromatography–Mass Spectrometry of N-Trifluoroacetyl Trimethylsilyl Esters of Some Iminodicarboxylic Acids
Authors: Kawashiro Katsuhiro , Morimoto Shiro , Yoshida Hideyuki
Published: July 2006

The simultaneous N-trifluoroacetylation and O-trimethylsilylation of some iminodicarboxylic acids were studied by the use of a mixture of α,α,α,α′,α′,α′-hexafluoro-N-methyldiacetamide and N,O-bis(trimethylsilyl)trifluoroacetamide, as a derivatizing reagent. The resulting N-trifluoroacetyl trimethylsilyl ester derivatives gave rather complicated mass spectra with molecular (M+) and M–15 (loss of CH3) ions upon electron impact at 20 eV.
Synthesis of Guanidino-1,3,5-triazines Using DMF
Authors: Iio Kokoro , Ichikawa Eiichi
Published: July 2006

2,4,6-Triguanidino-1,3,5-triazine and 2,4,6-tris(3-methylguanidino)-1,3,5-triazine were synthesized in 42 and 52% yields, respectively, by the cyclotrimerization of cyanoguanidine and 1-methyl-3-cyanoguanidine using DMF as a solvent in the presence of hydrogen chloride. 1-Phenyl-3-cyanoguanidine, 1,2-dimethyl-3-cyanoguanidine, and 2-imidazolidinylidenecyanamide, however, were cyclodimerized to the corresponding guanidino-1,3,5-triazines in a similar manner.
Electronic Structure and Lattice Distortion of Benzene Anion
Authors: Kimura Minoru , Kawabe Hiroyuki , Nishikawa Kiyoshi , Aono Shigeyuki
Published: July 2006

Electronic structure, especially the charge density or the spin density of the benzene anion (exactly dihydrophenylide ion) is investigated by the Hubbard Hamiltonian with vibronic interaction. Two limiting cases, i.e., I⁄β<<1 and I⁄β>>1 (I is the electron repulsion on site, β the absolute value of transfer integral.) are analytically examined. For whole range of this ratio, the numerical calculation has been performed. The actual system falls into the latter case, where the electron correlation produces a strong effect on the spin density distribution.
ESR Spectra of Benzene Anion
Authors: Kimura Minoru , Kawabe Hiroyuki , Nishikawa Kiyoshi , Aono Shigeyuki
Published: July 2006

Based on the spin density calculated in our previous paper, the ESR spectra of the benzene anion (exactly the dihydrophenylide ion) are analyzed by the Bloch equation. A hyperfine spectrum broader than those of usual aromatic radicals attributes to the chemical exchange process that the ion in question surrounded by solvent molecules undergoes a rotational motion characterized by the time τ which is the life time of chemical exchange. The line shape for each hyperfine spectrum is given in terms of 1⁄T2 and τ under the condition of τ⁄T2<<1.
Structure of Ni(II)– and Zn(II)–Glycinato Complexes in Aqueous Solution Determined by EXAFS Spectroscopy
Authors: Ozutsumi Kazuhiko , Yamaguchi Toshio , Ohtaki Hitoshi , Tohji Kazuyuki , Udagawa Yasuo
Published: July 2006

The EXAFS spectroscopy has been used to determine the structure of the bis(glycinato) complexes of nickel(II) and zinc(II) ions of low solubility (0.1–0.3 mol dm−3) in aqueous solution. The structural parameters were evaluated by the least-squares analysis both in the reciprocal and in the real spaces on the basis of various standard samples of known structures. Analysis of the EXAFS spectra of aqueous solutions containing the bis(glycinato) complexes of nickel(II) and zinc(II) ions has revealed that both complexes have two additional water molecules bound to the central metal ions to complete the octahedral structure. The structure of the nickel(II) complex is similar both in crystals and in solution, whereas the bis(glycinato)zinc(II) in solution is coordinated with two water molecules instead of two neighboring glycinato carbonyl oxygen atoms in the solid state.
Preparation and Stereochemistry of Cobalt(III) Complexes Containing 1,1,10,10-Tetraphenyl-4,7-diaza-1,10-diphosphadecane or 2,11-Dimethyl-5,8-diaza-2,11-diphosphadodecane, R2PCH2CH2NHCH2CH2NHCH2CH2PR2 (R=C6H5 or CH3)
Authors: Atoh Masamichi , Kashiwabara Kazuo , Fujita Junnosuke
Published: July 2006

New quadridentate phosphine ligands, 1,1,10,10-tetraphenyl-4,7-diaza-1,10-diphosphadecane (pp-PNNP) and 2,11-dimethyl-5,8-diaza-2,11-diphosphadodecane (mm-PNNP), were prepared from (ClCH2CH2NHCH2)· 2HCl and NaPR2 (R=C6H3, CH3) and purified through their Ni(II) complexes. Seven new cobalt(III) complexes containing the phosphine ligand were prepared: [CoX2(pp- or mm-PNNP)]n+(X2=(Cl)2, (NCS2), C5H7O2−(2,4-pentanedionate ion), and CO32−). Four complexes of [CoX2(pp- or mm-PNNP)]+ (X=Cl, NCS) afforded only a trans(X,X) isomer, and [Co(acac)(pp- or mm-PNNP)]2+ and [Co(CO3)(pp-PNNP)]+ complexes yielded a cisβ isomer. The geometrical structures were assigned on the basis of the NMR and visible-ultraviolet absorption spectra.
Reduction of Aryl Halides and N-Hydroxy Nitrogen Compounds in Fast Atom Bombardment Mass Spectrometry
Authors: Nakamura Takemichi , Nagaki Hidemi , Kinoshita Takeshi
Published: July 2006

Aromatic halogenated compounds and N-hydroxy nitrogen compounds were reduced to dehalogenated and deoxy analogs, respectively, in the fast atom bombardment ion source of a mass spectrometer. The reaction was found to occur in the liquid phase on exposure to a neutral fast atom beam.
Chemical Synthesis of a Heat-stable Enterotoxin of Yersinia enterocolitica
Authors: Yoshimura Shoko , Shimonishi Yasutsugu
Published: July 2006

A peptide with the amino acid sequence Ser–Ser–Asp–Trp–Asp–Cys–Cys–Asp–Val–Cys–Cys–Asn–Pro–Ala–Cys–Ala–Gly–Cys of heat-stable enterotoxin (ST) produced by Yersinia enterocolitica was synthesized by a conventional method. The synthetic peptide was found to be identical with the corresponding natural peptide by chemical and physicochemical criteria, thus establishing the amino acid sequence of an ST of Yersinia enterocolitica.
A Convenient Synthesis of 6-Hydroxy-7,9-bis(p-methoxybenzyl)-5-methylene-2-oxa-7,9-diazabicyclo[4.2.2]decane-8,10-dione
Authors: Yamaura Masanori , Suzuki Tsuneji , Hashimoto Hironobu , Yoshimura Juji , Shin Chung-gi
Published: July 2006

The title compound, the key intermediate for a total synthesis of bicyclomycin, was synthesized from N,N′-diacetyl anhydroglycine through twelve steps. The three-carbon branch for the construction of the bicyclic skeleton was introduced to the 2,5-piperazinedione ring as an alkylidene substituent, and then the olefinic function was converted into a diol function. The formation of bicyclic ring was achieved by treatment with N-bromosuccinimide followed by the intramoleculer substitution of the primary hydroxyl group in the side chain, and finally the secondary hydroxyl group was converted to the methylene function by an improved Peterson reaction.
The Carbon-13 NMR Spectra and Electronic Structure of 3H-Phenoxazin-3-ones
Authors: Hasegawa Kan-ichi , Ueno Yoshio
Published: July 2006

The 13C NMR chemical shifts of 3H-phenoxazin-3-one (1) and eighteen of its derivatives are reported. The chemical shifts of 1 can be explained in terms of a successive polarization of the π-conjugated framework by an electron-withdrawing carbonyl group and a π-donating ether oxygen. The principal factor solution for the chemical shifts of the 2-substituted 3H-phenoxazin-3-ones suggests that the first and the second factors collectively controlling the 2-substituent effect are electronic and steric effects, respectively. A dual substituent parameter analysis elucidated the transmission modes of the polar and resonance effects of the 2-substituents, and that the first and the fourth factor loadings multiplied by the corresponding standard deviation of the chemical shifts correlate with the CNDO/2 substituent-induced σ and π charge densities.
Intermolecular Bromine Transfer of 2-Amino-7-bromotropone Derivatives Catalyzed by Strong Acid
Authors: Wakabayashi Hidetsugu , Ishikawa Sumio , Okai Harue , Nozoe Tetsuo
Published: July 2006

Upon heating acetic acid containg a trace amount of coned sulfuric acid at 120 °C under nitrogen, 2-bromo-7-(2-hydroxyanilino)tropone (1a) gave 6-bromocyclohepta[b][1,4]benzoxazine (2a) as the main product and cyclohepta[b][1,4]benzoxazine, its 6,8-dibromo derivative and trace amounts of other mono-, di-, and tribromo compounds. This reaction became much more complex in the presence of oxygen. A similar bromine transfer was observed for 2-bromo-7-(dimethylamino)-, 7-(2-hydroxy-5-methylanilino)-, and 7-(2-methoxyanilino)tropone although the cite of the intermolecular bromine transfer depended upon the structures of the substrates and the reaction conditions. In contrast, 2a and 2-amino-5-bromotropone derivatives were completely stable towards the strong acid. Possible reaction pathways for this bromine transfer reaction are discussed.
Interaction of Hydrophobic Cyclic Dipeptides and Acylbenzenes as Studied by Fluorescent Quenching
Authors: Ootubo Toshiro , Kimura Shunsaku , Imanishi Yukio
Published: July 2006

The effect of the hydrophobic interaction on the association in aqueous media of tyrosine-containing cyclic dipeptides and 1-acyl-4-bromobenzenes having various lengths of acyl chain was investigated by quenching of the fluorescence of the former compounds by the latters. In ethanol, the change of fluorescence intensity (I0⁄I) was linearly related to the quencher concentration according to the Stern-Volmer’s plot, which was attributed to a dynamic quenching. In this case, structures of fluorophores and quenchers did not affect the quenching constant. However, in a buffer solution, I0⁄I was linearly related to the quencher concentration according to the Perrin’s plot, which was attributed to a static quenching. Perrin’s quenching constants depended on the structure of fluorophores and quenchers. In some cases, a quencher molecule was bound to a fluorophore by hydrophobic interaction in a favorable arrangement for fluorescent quenching. In aqueous solution, fluorophores and quenchers formed comparatively large aggregates with nonspecific arrangement for fluorescent quenching. In this case, Perrin’s quenching constants were independent of the nature of quenchers and related with the size of formed aggregates.
Use of Propagators in the Hückel Model. V. Polarizabilities
Authors: Aono Shigeyuki , Nishikawa Kiyoshi
Published: July 2006

The ordinary perturbation theory is reformulated in terms of propagators. It is well known that, if the perturbing interaction has a single particle character, the additional energy up to the second order of the perturbation is expressed by bond orders and various polarizabilities. This is easily rewritten by use of propagators. In addition, under the tight-binding approximation, the propagators of linear and ring polyenes are expressed in simple analytical forms, which enable us to give also analytical expressions for bond orders and polarizabilities. A simple application is given to determine which is more stable, anthracene or phenanthrene.
Optical Resolution of β-Hydroxynorvaline
Authors: Yamada Masaki , Okawa Kenji
Published: July 2006

β-Hydroxy-Dl-norvaline(HyNva) was successfully separated into its diastereoisorners by fractional crystallization from 2-propanol as p-toluenesulfonic acid(TsOH) salts. The two racemic diastereoisorners were resolved into four stereoisomers by Vogler’s method, using diastereomers of the N-benzyloxycarbonyl Dl-amino acid and l-tyrosine hydrazide.
Pressure and Temperature Effects on Conformational Equilibria between Rotational Isomers. II. Isobutyl and s-Butyl Halides in Hexane and Methanol
Authors: Nomura Hiroyasu , Koda Shinobu
Published: July 2006

The conformational changes in isobutyl halides (i-BuX) and s-butyl halides (s-BuX) in hexane and methanol have been analyzed by Raman spectroscopy as a function of temperature and pressure. The enthalpy and volume differences in the conformational changes from PC (trans) to PH (gauche) of i-BuX and from SHH(trans) to SHH′(gauche I) and to SCH(gauche II) of s-BuX in the dissolved state have been obtained. The enthalpy and volume differences, ΔH and ΔV, of all the conformational changes depended on the solvents and the concentration in solution. In the solution of hexane, the ΔH (PC→PH) of i-BuCl and i-BuBr both increased with a decrease in the concentration of i-BuX. The ΔV (PC→PH) of i-BuCl increased with an increase in the contents of the solvents, hexane, but that of i-BuBr decreased. The concentration dependences of ΔH and ΔV were discussed on the basis of the intermolecular interactions. The relation between ΔH and ΔV was also discussed on the basis of thermodynamic consideration.
Studies of the Hydrous Niobium(V) Oxide Ion Exchanger. II. Affinity for Various Cations
Authors: Inoue Yasushi , Yamazaki Hiromichi , Okada Kazushi , Morita Kazuhiko
Published: July 2006

In order to elucidate the fundamental properties of hydrous niobium(V) oxide as a cation exchanger, the stoichiometry of cation exchange and the selectivity for various cations were studied. As the reversibility and the equivalent exchange between the cations were confirmed, this material showed an ideal cation-exchange reaction. The affinity series for alkali metal ions and alkaline earth metal ions were Cs+>>K+>>Li+ and Ba2+>>Sr2+≥Ca2+>Mg2+ respectively; the values decreased in the order of the increase in the hydra ted ionic radii of the cations. For transition metal ions, the distribution coefficients had a strong correlation with the first hydrolysis constants of the cations and/or the first stability constants of their acetato complexes. Based on this finding, the transition metal ions are considered to be adsorbed on the exchanger by a bond partially covalent in character, rather than by a pure ionic bond. The pH-dependency of the distribution coefficients of the cations was discussed in terms of the effects of the dissociation of the exchange sites on the overall ion-exchange equilibrium.
Syntheses and Crystal and Molecular Structure of [Hexaaquabis(2-naphthalenesulfonato)lanthanoid(III)] 2-Naphthalenesulfonate Trihydrate, [Ln(C10H7SO3)2(H2O)6] (C10H7SO3)·3H2O (Ln=Pr, Nd, Sm, Eu, Gd, Dy, Er, and Yb)
Authors: Ohki Yoshiyuki , Suzuki Yasuo , Nakamura Masao , Shimoi Mamoru , Ouchi Akira
Published: July 2006

Eight isomorphous 2-naphthalenesulfonato complexes of lanthanoids(III) (Pr, Nd, Sm, Eu, Gd, Dy, Er, and Yb) were synthesized, and the structures of five of them were determined by the single-crystal X-ray-diffraction method. They are monoclinic, with the space group of P21; the cell constants of the PrIII complex, for example, were a=18.228(8), b=7.498(4), c=14.177(9) Å, β=107.75(4)°, Z=2, and its final R value was 0.043. The unit-cell size of the complex decreases with the increase in the atomic number of the metal atom. The central metal atom is in a square-antiprism geometry and is octa-coordinated with two unidentate 2-naphthalenesulfonato ligands and six water–oxygen atoms. Nonligated oxygen atoms of the sulfonato ions form hydrogen-bonds with the coordinated and lattice water molecules to form a double-layered network along the ab-plane. All the naphthalene rings stand together to form hydrophobic sheets between the hydrogen-bonding networks.
Conductometric Study of Cobalt(II), Nickel(II), Copper(II), and Zinc(II) Perchlorates in Methanol–Ethylene Glycol Mixtures
Authors: Doe Hidekazu , Kitagawa Toyokichi
Published: July 2006

The ionic association constants of M(ClO4)2 (M=Co, Ni, Cu, Zn) were determined by conductometric measurements in methanol–ethylene glycol mixtures of 100, 80, 60, 40, 20, and 0 wt% methanol compositions at 5, 15, 25, 35, and 45 °C. The conductometric data were analyzed using a modified Fuoss and Edelson method. The association constant of an ion pair M2+ClO4−, K1A, was studied and thermodynamic functions, ΔH1A\ominus and ΔS1A\ominus, for that association were determined at 25 °C. Free-energy changes, ΔG1A\ominus (=–RTlnK1A), at 25 °C which slowly decreased with an increase in the ethylene glycol content in a solvent, are in good agreement with estimates from Fuoss’ theory regarding ionic association. Values of both ΔH1A\ominus and ΔS1A\ominus were positive in many systems: i.e., unfavorable enthalpy and favorable entropy changes, and those were obtained near to estimates from the Fuoss’ theory in pure methanol, 100 wt%. However, there have been a few systems with a negative ΔH1A\ominus (Co, Ni, and Zn at 40 and 20 wt%, and Co at 0 wt%), contrary to theoretical expectations. These results are discussed from the standpoint of a changing solvation between M2+ and MClO4+. In all the solvents, moreover, the ΔH1A\ominus and ΔS1A\ominus values have been in a sequence according to Co<NiZn. The results of limiting molar conductances, Λ0, are discussed regarding Walden products.
ESR Studies on Salicylaldehyde Schiff Base Complexes of Copper(II). I. Bis(N-cyclohexyl- and N-cycloheptyl-salicylideneaminato)copper(II) Complexes and Their Derivatives in Polycrystals
Authors: Takeuchi Akira , Yamada Shoichiro , Yokoi Hiroshi
Published: July 2006

Twelve of the title complexes including color isomers show powder ESR spectra of various line shapes. These complexes are a novel series of copper(II) complexes which have very weak intermolecular spin-exchange interactions in crystals. Brown complexes and most green complexes show monomer and dimer ESR spectra, respectively. It is demonstrated by ESR measurements that the above green complexes are transformed into the brown ones only by grinding those green crystals finely and forcefully with agate mortar and pestle.
Physicochemical Speciation of Trace Elements in River Water by Means of Ultrafiltration
Authors: Tanizaki Yoshiyuki , Yamazaki Masao , Nagatsuka Sumiko
Published: July 2006

Ultrafiltration and Millipore filtration techniques have been used in the speciation of trace elements in Tama River water. The size distribution was clarified for 32 elements by means of neutron-activation analysis in order to discuss their chemical or physical forms. Alkali and alkaline-earth elements were primarily found in the dissolved-size fraction (<0.45 μm). Their dissolved species were mostly distributed in the smallest-molecular-weight fraction (<MW 500), although the alkaline-earth elements were also recognized to a significant extent (20–30%) in the middle-molecular-weight fraction (MW 104–500). Transition elements were principally associated with the suspended-size fraction (>0.45 μm) in the upper reaches of the river, but in the lower reaches they were chiefly fractionated as the dissolved species, with the exception of Sc and Fe. The dissolved V and Mn were distributed in the smallest-molecular-weight fraction, while the Co, Ni, and Zn were divided between two smaller-molecular-weight fractions (MW 104–500 and <MW 500). Light rare-earth elements were mostly associated with suspended materials. Heavier rare-earth elements were, on the contrary, mainly found in the dissolved-size fraction, while their dissolved species were concentrated in the middle-molecular-weight fraction. The dissolved species for As, Se, Sb, and W were divided into two smaller-molecular-weight fractions, although As, Se, and W were predominantly found in the middle-molecular-weight fraction and Sb was mainly detected in the smallest-molecular-weight fraction. Aluminium and Ag were mainly associated with suspended materials. Furthermore, the dissolved Al was mostly distributed in the smallest-molecular-weight fraction, while the Ag was concentrated in the largest-molecular-weight fraction (>MW 104).
Methods for Observing the Deformation of an Aqueous Paramagnetic Solution in a Magnetic Field
Authors: Yasuoka Takashi , Kidokoro Tadahiko , Mitsuzawa Shunmei
Published: July 2006

Two methods have been worked out for the observation of the deformation of a paramagnetic aqueous solution in a magnetic field. The deformation was observed on: (1) a layer of a solution covered with a water-immiscible organic liquid and (2) a drop of the solution suspended in the liquid.
Selective Synthesis of LPG from Synthesis Gas
Authors: Fujimoto Kaoru , Saima Hitoshi , Tominaga Hiro-o
Published: July 2006

C2–C4 paraffins were produced from synthesis gas with selectivities higher than 80% at 300 °C and 21 atm by utilizing hybrid catalysts composed of a methanol-synthesis catalyst and a Y-type zeolite. The diffusion of lower olefins within zeolite pores and their hydrogenation on a methanol-synthesis catalyst were found to be important factors in controlling selectivity.
Synthesis and Properties of the [n](2,5)Pyridinophane Ring System
Authors: Kobayashi Tomoshige , Nitta Makoto
Published: July 2006

The synthesis and properties of a series of [n](2,5)pyridinophane derivatives (13a–e) (n=10, 8, 7, and 6) are described. These compounds are prepared in low yields by the [Mo(CO)6]-induced cycloaddition reaction of 3-aryl-4,5-polymethylene-substituted isoxazoles (11a–e) with dimethyl acetylenedicarboxylate. The reaction pathways are suggested to involve the inclusion of the acetylenic ester across the C-4–C-5 bond of the N-complexed isoxazoles and the subsequent elimination of the oxygen atom from the resulting isoxazoline ring. The structures of 13a–e are established on the basis of the 1H-NMR, 13C-NMR, and UV spectra. A significant strain for the pyridine ring in 13a–e is reflected in the UV spectra. As the [n] decreases in 13–e, there is a red shift in the absorption spectra. This feature is in good accordance with that observed in a series of [n]paracyclophane ring systems.
Aryliminodimagnesium Reagents. IX. The Reaction with Benzophenones. The Mechanism of Coordination and Electron Transfer Processes Distinct from That of Grignard Reaction
Authors: Okubo Masao
Published: July 2006

In the reaction of aryliminodimagnesium reagents(ArN(MgBr)2, Ar=C6H5, p-MeC6H4, and p-MeOC6H4) with some p-substituted benzophenones, the arylaminyl radicals(ArNMgBr) derived from the reagents were detected by ESR in low concentrations and identified by computer simulation. From comparison of all the itemized facts characteristic of the reaction with those of Grignard reaction of the same substrates, the mechanisms of initial coordination and electron transfer of the two reactions were distinguished.
The Pyrolyses of 1,1,4,4,-Tetraphenyl-1,4-butanediol and 1,1,4,4-Tetraphenyl-2-butene-1,4-diol Derivatives. Decomposition Reactions to Form Olefins via the Elimination of Two Mole Equivalents of the Hydroxydiphenylmethyl Radical
Authors: Saito Katsuhiro , Horie Yoichi , Mukai Toshio , Toda Takashi
Published: July 2006

The pyrolysis of 1,1,2,4,4-pentaphenyl-1,4-butandiol, trans-1,2-bis(hydroxydiphenylmethyl)hexane, trans-1,2-bis(hydroxydiphenylmethyl)indan, and cis-endo- and trans-1,2-bis(hydroxydiphenylmethyl)bicyclo[2.2.1]heptane gave styrene, cyclohexene, indene, and norbornene respectively, accompanied by benzophenone and benzhydrol. The pyrolysis of trans-1,2-bis(hydroxydiphenylmethyl)spiro[2.6]nona-4,6,8-triene afforded indene via rearrangement to form trans-1,2-bis(hydroxydiphenylmethyl)indan. The pyrolysis of cis-1,1,4,4-tetrapheny 1-2-butene-1,4-diol afforded 2,2,5,5-tetraphenyl-2,5-dihydrofuran. On the other hand, trans-1,1,4,4-tetraphenyl-2-butene-1,4-diol afforded 1,2,4,4-tetraphenyl-3-buten-1-one. The mechanisms of these decomposition reactions are discussed.
Effects of Alkyl Chains of Thiacarbocyanine as the Sensitizer for the Photoreduction of Methylviologen in Micellar Phase
Authors: Nakagaki Masayuki , Komatsu Hiroaki , Handa Tetsurou
Published: July 2006

Photoinduced reduction of methylviologen (MV2+) by ethylenediaminetetraacetate was investigated with 3,3′-dialkylthiacarbocyanines as a sensitizer in the micellar solution of a nonionic surfactant, heptaethylene glycol monododecyl ether. The alkyl chains of the dyes were found to have considerable effects on the reaction rate. The fluorescence yield of a dye having two long alkyl chains, 3,3′-dioctadecylthiacarbocyanine (C18–18) in the micellar phase was larger than that of the dye having only one long alkyl chain, 3-methyl-3′-octadecylthiacarbocyanine (C1–18). This result was discussed in terms of the large effective volume associated with the intramolecular twisting motion in the excited state of C18–18. Also, from the fluorescence quenching experiments, it was found that MV2+ was of easier access to C18–18 than C1–18 in the micellar phase. Thus, the relatively higher stability of the excited state of C18–18 and the easier access of MV2+ to C18–18 were considered to be responsible for the faster reaction rate achieved by C18–18 than by C1–18 in the micellar solution.
Studies of the Hydrous Niobium(V) Oxide Ion Exchanger. III. The Effect of Heat Treatment
Authors: Inoue Yasushi , Yamazaki Hiromichi , Matsuda Yuzo
Published: July 2006

The effects of heat treatments in air have been studied regarding the properties of a hydrous niobium(V) oxide ion exchanger in H+ form. The exchanger lost 17 per cent of the initial ion-exchange capacity when it was heat-treated at 110 °C; thereafter the exchange capacity decreased progressively with temperature until 400 °C, at which point it retained about a half of the initial value. The exchanger began to crystallize into γ-phase at a temperature between 450 to 500 °C where the capacity disappeared. The γ-phase transformed to α-phase at a temperature above 800 °C. An examination of the uptake curves showed that less-acidic exchange sites were more resistant than more-acidic sites to heat treatment. The existence of three kinds of water in the exchanger (adherent, zeolitic, and bound) has been suggested on the basis of the ion-exchange capacity, the thermal-analysis curves, and water recovery brought about by humidifying.
Simultaneous Multielement Determination of Trace Metals in Seawater by Inductively Coupled Plasma Atomic Emission Spectrometry Using Chelating Resin Column Preconcentration
Authors: Chu Jia Cheng , Akagi Tasuku , Haraguchi Hiroki
Published: July 2006

Preconcentration of trace metals in seawater using a Chelex-100 resin column was investigated for simultaneous determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimum preconcentration conditions were examined in detail. With 100 ml of 1 M ammonium acetate buffer solution (1 M=1 mol dm−3), the matrix elements in seawater could be removed sufficiently without loss of analytes. The concentration factor of 200 times could be achieved by dissolving the dried HNO3 eluent of the column. The blanks of the method were negligibly small for most elements investigated. The detection limits were in the range of several ng/1 to 100 ng/1 for Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn. The present technique was applied to the determination of trace metals in coastal and ocean seawater.
X-Ray Diffraction, Raman, and NMR Studies on Tetrathiocyanato Complexes of Zinc(II), Cadmium(II), and Mercury(II) Ions in Aqueous Solution
Authors: Yamaguchi Toshio , Yamamoto Kiyoshi , Ohtaki Hitoshi
Published: July 2006

X-Ray scattering, Raman, and 13C- and 14N-NMR measurements were performed on aqueous solutions containing tetrathiocyanato complex ions of Zn(II), Cd(II), and Hg(II). The radial distribution functions revealed that four thiocyanate ions tetrahedrally coordinated to Zn(II) and to Hg(II) ions through the N and S atoms, respectively, while Cd(II) ion was bound to two sulfur and two nitrogen atoms within the coordinated four SCN− ions. The bond distances and bond angles are as follows: Zn–N 204 pm, Cd–N and Cd–S 225 and 265 pm, respectively, and Hg–S 254 pm, and Zn–N–C 145°, Cd–N–C and Cd–S–C 149° and 106°, respectively, and Hg–S–C 102°. The Raman bands of the C–S vibration within the tetrathiocyanato complexes of Zn(II), Cd(II), and Hg(II) ions in aqueous solutions appeared at 821 and 710 cm−1 for the Zn(II) and Hg(II) complexes, respectively, consistent with the values in the literature. The C–S stretching Raman bands of tetrathiocyanatocadmate(II) complex were resolved into two components at 779 and 732 cm−1. The C–S frequency shifted toward the higher frequency side than that (747 cm−1) of the free SCN− ion in the case of the binding of SCN− to metal ion via the N atom in the Zn(II) and Cd(II) cases, while the C–S bands influenced by the M–S bonding appeared on the lower frequency side in the Cd(II) and Hg(II) complexes. The 13C chemical shifts of the tetrathiocyanato complexes in aqueous solutions showed the downfield and upfield shifts for Zn(II) and Hg(II), respectively, and the intermediate for Cd(II). The nitrogen-14 resonance in [M(SCN)4]2− in aqueous solutions shifted upfield (−30.8 ppm) for Zn(II), downfield (30.3 ppm) for Hg(II), and in between for Cd(II) (−1.3 ppm). The trend of the 13C- and 14N-chemical shifts supported the different types of binding of ambient SCN− ion deduced from the X-ray and Raman measurements.
Ion-exclusion Chromatography of Weak Acids Using a Carbonic Acid Solution as Eluent
Authors: Itoh Hisaaki , Shinbori Yoshio
Published: July 2006

Ion-exclusion chromatographic separation of organic acids using a carbonic acid solution as eluent is presented. This permits conductivity detection of ionic species without a suppressor as a post-column reactor. It was found that the proposed method was applicable to the separation of organic acids having pKa over ca 3.5. This technique was applied to the determination of acetic acid in pharmaceuticals without tedious sample preparation.
Use of Alternating Current Impedance Method in Diagnosing Electrode Kinetics of [Fe(CN)6]4−⁄3− Complex Confined to Protonated Poly(4-vinylpyridine) Film on Graphite Surfaces
Authors: Ohsaka Takeo , Ushirogouchi Toru , Oyama Noboru
Published: July 2006

A “heterogeneous” electron-transfer process of [Fe(CN)6]4−⁄3− redox couple, which was confined electrostatically to the protonated poly(4-vinylpyridine) (PVP) film, at basal-plane pyrolytic graphite (BPG) electrode/ PVP film interfaces and a “homogeneous” charge-transport process within the PVP film were examined by alternating current (ac) impedance method. The obtained impedance loci were found to correspond to those expected for the electrochemical impedance expressed by “Randles’s equivalent circuit.” The relevant kinetic parameters (i.e., the standard rate constant, k° and the cathodic transfer coefficient, α) of the electrode reaction, the apparent diffusion coefficients, Dapp, for the “homogeneous” charge-transport within the film, the double-layer capacity, Cd1 and the solution resistance, Rsoln were determined at various concentrations of [Fe(CN)6]3− in PVP coatings. The obtained Dapp, k°, and α values were compared with those recently obtained by normal pulse voltammetry. In addition, an equivalent circuit model is given for the impedance obtained for the redox reaction on a BPG electrode coated with a protonated PVP confining [Fe(CN)6]4−⁄3− couple.
A Study of the Inter-elemental Effect in the Carbon-furnace Atomic-absorption Spectrometry of Selenium and Mercury in Biological Samples by the Palladium-addition Method
Authors: Liu Ping , Wei Lei , Matsumoto Kazuko , Fuwa Keiichiro
Published: July 2006

In the electrically-heated carbon-furnace atomic-absorption spectrometry of selenium and mercury, interelemental interference is present between the two elements. Mercury has no effect on selenium sensitivity in a simple inorganic selenium solution. When, however, the solution contains organic materials such as 0.5% albumin, the selenium sensitivity is decreased. The presence of mercury in addition to the organic material further decreases the sensitivity to about a half of that of a solution containing only selenium and albumin. The addition of 0.94 mmol dm−3 palladium ion completely removes the negative interferences due to organic materials and mercury. On the other hand, in mercury determination the presence of organic materials also decreases the mercury sensitivity. The addition of palladium, in contrast to selenium determination, enhances the mercury sensitivity about 50 times, independent of whether or not the solution contains organic materials.
Synthetic Studies of Pyridomycin. IV. Syntheses of Some Twelvemembered Ring Compounds Designed for Construction of Intact Ring System with Exocyclic (Z)-s-Butylidene Side Chain in Pyridomycin
Authors: Kinoshita Mitsuhiro , Mori Yasuharu
Published: July 2006

(2R,5R,6S,9S,10S,11R)-10-Hydroxy-2-[(1′S)-1′-Hydroxy-1′-methylpropyl]-5,11-dimethyl-9-(3-pyridylmethyl)6-(benzyloxycarbonylamino)-8-aza-1,4-dioxacyclododecane-3,7,12-trione and its 1′-O-methyl derivative, and (2S,1′R)-diastereomer of the latter have been enantiospecifically synthesized from sugar and l-threonine derivatives. The attempts to convert them into a pyridomycin precursor with the 2-(Z)-s-butylidene side chain were unsuccessful.
Kinetic Studies of Fast Equilibrium by Means of High-performance Liquid Chromatography. XII. Rate Constants and Energy Barriers of Intramolecular Carbonyl–Nitrogen Bond Rotation of o-Substituted Acetanilides
Authors: Moriyasu Masataka , Kawanishi Kazuko , Kato Atsushi , Hashimoto Yohei , Sugiura Makiko , Sai Torei
Published: July 2006

A novel high-performance liquid chromatographic(HPLC) method has been proposed to determine the rate constants and activation energies of the interconversion between two labile species existing in equilibrium in solution. The rotational energy barriers to intramolecular bond rotation about the carbonyl–nitrogen bonds of several o-substituted acetanilides have been determined by this method. These energy barriers have been found to increase when bulkier groups are attached at the o-position on the benzene ring. These have also been determined by a dynamic nuclear magnetic resonance spectroscopic(DNMR) method, which gives good agreement with the HPLC results.
4,4′,4″-Tris(levulinoyloxy)trityl as a New Type of Primary Hydroxyl Protecting Group
Authors: Sekine Mitsuo , Hata Tsujiaki
Published: July 2006

The 4,4′,4″-tris(levulinoyloxy)trityl (TLTr) group was introduced selectively on the 5′-oxygen of thymidine by use of in situ generated 4,4′,4″-tris(levulinoyloxy)trityl bromide. The TLTr group was found to be sufficiently stable to acids and readily removed by hydrazinolysis followed by warming to 50 °C in pyridine–acetic acid without damage of other protecting groups such as the O-acetyl and 4,4′-dimethoxytrityl groups. The utility of this new protecting group was demonstrated by the successful synthesis of thymidylyl(3′–5′)-thymidine where the TLTr group was employed as the 5′-hydroxyl-protecting group.
Optical Absorption and Conductimetric Studies on Ionic Dissociation of Metallotetraphenylporphyrins in Ethanol Solutions
Authors: Hoshino Mikio , Katayama Shunzo , Yamamoto Kiyoko
Published: July 2006

Optical absorption spectra of chloro[tetraphenylporphyrinato(2-)]metals, MIIICl(tpp) (M=Mn, Fe, Co, and In), and diacetato[tetraphenylporphyrinato(2-)]tin(IV), SnIV(CH3COO)2(tpp), in ethanol and benzene solutions were measured. A marked difference in the absorption spectra between the ethanol and benzene solutions was observed for MIIICl(tpp), FeIIICl(tpp), and CoIIICl(tpp), while a small difference for InIIICl(tpp) and SnIV(CH3COO)2(tpp). The electric conductivity measurements demonstrated that MIIICl(tpp) (M=Mn, Fe, Co, and In) undergoes ionic dissociation in ethanol, whereas SnIV(CH3COO)2(tpp) does not. Solvent effects on the optical absorption spectra observed for ethanol and benzene solutions of the metallotetraphenylporphyrins are discussed on the basis of (1) the ionic dissociation revealed from the conductivity measurements and (2) charge-transfer (from porphyrin ligand to the central metal) character of the electronic absorption bands.
Magnetic-field Effect on the Thermal Decomposition of Dilauroyl Peroxide
Authors: Tanimoto Yoshifumi , Nishino Masato , Itoh Michiya
Published: July 2006

In the thermal decomposition of dilauroyl peroxide in octane, the yield of docosane increases by 3–6% in the presence of magnetic fields (0.15–1 T). The results are interpreted in terms of a radical–pair model.
Formation of α-Methylstyrene Dimer Radical Cations via Molecular Aggregates Studied by Pulse Radiolysis
Authors: Yamamoto Yukio , Chikai Yukio , Hayashi Koichiro
Published: July 2006

Pulse radiolysis of α-methylstyrene was carried out in 1,2-dichloroethane, and the effect of additives on the formation of the dimer radical cations was investigated. In the presence of excess amounts of hexenes and biphenyl, the dimer radical cations are suggested to be formed via molecular aggregates by charge-transfer reactions.
Olefin Hydrogenation over ZSM-5 Type Zeolite Catalysts Modified with Alkaline Earth Metals
Authors: Sano Tsuneji , Okabe Kiyomi , Shoji Hiroshi , Saito Kenji , Yasumoto Yoshiro , Hagiwara Hiroyuki , Takaya Haruo
Published: July 2006

Olefin hydrogenation was carried out over ZSM-5 type zeolite catalysts modified with various alkaline earth metals. It was found that the catalytic activity of H–ZSM-5 for the olefin hydrogenation decreases upon such a modification.
The Reaction of Dimethyl N-Benzoylcarbonimidodithioates with Amines
Authors: Fukada Naoaki , Hayashi Masahiro , Suzuki Yukari
Published: July 2006

1-Substituted 3-benzoyl-2-methylisothioureas and 1,3-disubstituted 2-benzoylguanidines were synthesized from dimethyl N-benzoylcarbonimidodithioates and amines. From ethylenediamine and 2-aminoethanol, imidazolidine and oxazolidine derivatives were obtained respectively.
Palladium-catalyzed Displacement of Aryl Halide by Tin Analogue of Reformatsky Reagent
Authors: Kosugi Masanori , Negishi Yoshikazu , Kameyama Masayuki , Migita Toshihiko
Published: July 2006

Reaction of ethyl α-(tributylstannyl)acetate with aryl bromides in the presence of zinc bromide or chloride and a catalytic amount of dichlorobis(tri-o-tolylphosphine)palladium was found to give ethyl arylacetates in good yields except with the aryl bromide having p-acetyl or p-nitro group.
Cycloreversion Reaction of Cage Compounds Initiated by Aminium Cation Radical Salts
Authors: Hasegawa Eietsu , Mukai Toshio
Published: July 2006

Treating cage compounds 1 with triarylaminium cation radical salts, 3 and 4, resulted in the effective conversion of 1 to dienes 2. The cation radical isomerization induced by electron-transfer from 1 to aminium salt was suggested by the effect of substituent of 1 as well as by the effect of addition of electron donors as quenchers.
Synthesis of Alkyl Dihydrogenphosphate by the Reaction of Alcohols and Silyl Polyphosphate
Authors: Okamoto Yoshiki
Published: July 2006

Alkyl dihydrogenphosphates were readily prepared by phosphorylation of alcohols with trimethylsilyl polyphosphate or polyphosphorylated silica-gel.
Stereoselective Synthesis of (E)-Alkylidenesucdnates by Palladium-catalyzed Carbonylation
Authors: Yamamoto Keiji , Deguchi Ryoji , Tsuji Jiro
Published: July 2006

(E)-Alkylidenesuccinates have been prepared stereoselectively starting with acrylates by a three-step procedure involving a palladium-catalyzed carbonylation of allylic carbonates.
Chlorination of Poly(vinyltoluene) by Electrolysis in an Organic/Water Suspension System
Authors: Matsuda Yoshiharu , Morita Masayuki , Yamamoto Hiroshi , Watanabe Hiroyuki , Seita Tooru , Akimoto Akira
Published: July 2006

Chlorinated poly(vinyltoluene) was synthesized by controlled-current electrolysis of poly(vinyltoluene) in a suspension system consisting of aqueous and organic solutions. A high Cl-content polymer, in which Cl was introduced to the methyl group and the main chain, was obtained without changes in the molecular-weight distribution of the polymer.