bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Trace Metals Forming Large Molecular Complexes in Natural Waters as Estimated by Ultrafiltration/Liquid Chromatography/Atomic Spectroscopy
Authors: Kobayashi Kensei , Akagi Tasuku , Haraguchi Hiroki
Published: July 2006

Concentration of trace metals forming complexes with large organic molecules in natural waters have been determined. Natural water samples (sea water and lake water) were filtered through a membrane filter (pore size: 0.45 μm) just after sampling, and concentrated by ultrafiltration. The concentrated natural water samples were fractionated by high performance gel filtration chromatography, and metal ion concentration in each fraction was determined by inductively coupled plasma atomic emission spectrometry and/or by graphite furnace atomic absorption spectrometry. Concentration of zinc forming large molecular complexes (LMC) in sea water was 0.07 ngmL−1, and that in lake water was 0.06 ngmL−1. Copper, iron, vanadium, and molybdenum forming LMC in natural waters were also determined. The present results suggest the existences of LMC-forming metal ions, some of which may be metalloenzymes dissolved in natural waters.
Polarographic Behavior of Metal Ions in the Presence of Polyethylene Glycol in Potassium Chloride1
Authors: Kurotu Takuzo
Published: July 2006

The polarographic behavior of Cu(II), Pb(II), Tl(I), Sn(II), In(III), Cd(II), and Zn(II) was investigated in the presence of polyethylene glycol (PEG) in 0.1 mol dm−3 potassium chloride. PEG was adsorbed on mercury drops within the potential range from ca.−0.2 through −1.50 V vs. SCE, and shifted the half-wave potentials of Sn(II), In(III), Cd(II), and Zn(II) toward the negative direction, leaving the wave heights unchanged. On the other hand, the polarograms of Cu(II), Pb(II), and Tl(I) were not affected by the presence of PEG. Linear relationships between the wave heights for Cu(II), Pb(II), In(III), Cd(II), Zn(II), and their concentrations were obtained in the presence of PEG. Among these ions, the polarographic waves of In(III) and Cd(II), whose reduction potentials are very close together, became well separated in the presence of PEG. It is, therefore, possible simultaneously determine In(III) and Cd(II) in this medium. Interference between In(II) and Pb(II) was observed in freshly prepared solutions. It is, however, feasible to precisely determine both ions by using PEG as a reduction potential-shift reagent for In(III) in order to eliminate the interference.
Kinetics and Mechanism of the Oxidation of Ethyl Acetoacetate and Diethyl Malonate by Dodecatungstocobaltate(III)
Authors: Gupta Mala , Saha Swapan K , Banerjee Pradyot
Published: July 2006

The reactions of dodecatungstocobaltate(III) with ethyl acetoacetate (EAA) and diethyl malonate (DEM) have been studied in aqueous acidic medium at 60°C. A first-order dependence of rate on both the concentrations of oxidant and reductant is obtained and the reactions are catalyzed by alkali metal ions. The general rate law for the reactions is expressed as kobs=2(k0+[M+])[R] where k0 and k denote the spontaneous and catalyzed paths respectively and [R], the reductant concentration. For EAA oxidation the values of k0=(1.82±0.10)×10−4 dm3 mol−1 s−1 and kLi+=(2.23±0.09)×10−3dm6 mol−2 s−1, kNa+=(1.19±0.07)×10−3 dm6 mol−2 s−1, kk+=(1.01×0.02)×10−3 dm6 mol−2 s−1. The corresponding values for DEM are k0=(2.63±0.07)×10−5 dm3 mol−1 s−1 and kLi+=(2.11±0.07)×10−4 dm6 mol−2 s−1, kNa+=(9.13±0.25)×10−5 dm6 mol−2 s−1, kK+=(8.25±0.06)×10−5 dm6 mol−2 s−1. The less resonance stabilization of the protonated free radical species compared to the free radical obtained from the ester itself in the rate-determining step would cause a lowering in rate and this seems to explain the [H+]−1 dependence for the ester oxidations. A plausible mechanism considering an outer-sphere association between the complex and reductant has been suggested. The phenomenon of catalysis is explained by assuming an intermediate bridge formation via alkali metal ions between the reactants.
Formation of Molecular Complexes of a Water-Soluble Porphyrin with Amino Acids: Importance of Hydrophobic Interaction
Authors: Tabata Masaaki , Shimada Akinobu
Published: July 2006

Amino acid interacts with 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (H2TPPS4) to form molecular complex. The formation constants (logK) defined as HA+H2TPPS4\ightleftharpoonsHA·H2TPPS4 were found to be 2.00±0.05, 1.43±0.03, 0.83±0.02, −0.41±0.07, and −0.96±0.09 for l-tryptophan (Trp), l-tyrosine (Tyr), l-phenylalanine (Phe), l-leucine (Leu), and l-valine (Val) respectively, at 25°C and an ionic strength of 0.1 mol dm−3 (NaNO3), where HA denotes a neutral form of amino acid. The formation constants are linearly correlated to the hydrophobicity of the side-chain of amino acid: l-tryptophan exerts the largest interaction with porphyrin among them. Amino acids also interact with porphyrin adsorbed to an anion-exchange resin. Partition coefficient and retention volume were determined by batch and column methods using the porphyrin-loaded resin. The distribution coefficient and the retention volume of amino acid increase with the hydrophobicity of side-chain of amino acid. The formation of the molecular complex was also confirmed by 1H NMR spectra for H2TPPS4/Trp and H2TPPS4/Leu.
Preparation of Single Crystals of a New Compound, Ta5B6 by the Aluminium-Flux Method
Authors: Okada Shigeru , Hamano Kenya , Higashi Iwami , Lundström Torsten , Tergenius Lars-Erik
Published: July 2006

Single crystals of a new compound Ta5B6 was prepared by the high temperature aluminium solution method using tantalum and boron powder as starting materials in an argon atmosphere. The experimental conditions for obtained single crystals of relatively large size were established. The optimum conditions for growing Ta5B6 single crystals were found to include atomic ratios of starting materials B/Ta=1.2 and Al/Ta=8.38, soaking temperature 1650°C, soaking time 5 h and a cooling rate of 25°C h−1. Single crystals of Ta5B6, having a grey color and metallic luster, were generally obtained in the form of an irregular or trapezoidal shape: the latter crystals were enclosed by two large {010} planes. The largest crystals prepared have maximum dimensions of about 0.12mm×0.13mm×0.23mm. The crystals are orthorhombic with a space group of either Cmm2, Cm2m, C222, or Cmmm and the unit cell dimensions a=3.1385(10) Å, b=22.609(7) Å, c=3.2865(8) Å, and V=233.20(12) Å3. The X-ray density is 13.808(2) g cm−3. The present study of growing Ta5B6 crystals is the first single crystal growth study of a V5B6 type crystal.
Thermodynamics and Kinetics of Propidium Binding to Poly(A)·Poly(U) in Aqueous Solution
Authors: Sugimoto Naoki , Monden Noriko , Sasaki Muneo
Published: July 2006

The propidium binding to poly(A)·poly(U) has been investigated thermodynamically and kinetically in buffers containing different concentrations of NaCl at various temperatures. Free propidium had an absorption maximum at 493 nm, and this shifted to about 530 nm for propidium fully bound to poly(A)·poly(U) in all solutions. The association constant for the reaction was 1.42×106 mol−1 dm3 at 2.02×10−2mol dm−3 of Na+concentration, and about 26 times larger than that at 1.02 mol dm−3 Na+. The dependence of the association constants indicated the enthalpies for the reaction at the low and high Na+ concentrations were 39.8 and −8.3 kJ mol−1, respectively. The entropies were 251 and 63 J K−1 mol−1, respectively. These thermodynamical results suggested that the association reaction of propidium to poly(A)·poly(U) may play different behaviors at the low and high salt concentrations. Kinetic results by a micro stopped-flow method indicated that the propidium binding to poly(A)·poly(U) was a single step at the low Na+ concentration, while at the high Na+concentration it consisted of two steps which contained the slow unimolecular process after the binding step.
NMR Spectra of Organogermanium Compounds. IX. NMR Spectra and Molecular Mechanics Calculations of 1-t-Butylgermacyclohexanes
Authors: Takeuchi Yoshito , Tanaka Katsumi , Harazono Toshie , Yoshimura Shin
Published: July 2006

A variety of t-butylgermacyclohexanes was prepared and their 13C and 73Ge (when possible) NMR spectra were determined. It was estimated that the conformational energy of a t-butyl group bonded to germanium is about 1.3 kcal mol−1 by NMR data though the molecular mechanics calculations gave variable results depending on the parameter for germanium used; 0.33 kcal mol−1 by Allinger’s parameter while 1.23 kcal mol−1 by Ouellette’s parameter. The origin of this discrepancy was discussed. The molecular orbital calculations (MNDO) gave an intermediate value (0.60 kcal mol−1).
Thermal Decomposition of 2,2-Bis(t-butyldioxy)alkanes
Authors: Suyama Shuji , Watanabe Yasumasa , Sawaki Yasuhiko
Published: July 2006

The thermal decomposition of 2,2-bis(t-butyldioxy)propane (1a) has been studied in cumene. The activation parameters obtained by the thermolysis of la are ΔH\eweq=145.6kJ mol−1 and ΔS\eweq=47.3 J K−1 mol−1. The decomposition products of 1a are acetone, t-butyl alcohol, t-butyl hydroperoxide, t-butyl peracetate, t-butyl 1-methyl-1-phenylethyl peroxide, and bis(1-methyl-1-phenylethyl). The peroxyacetal cleaves homolytically at one of dioxy bonds to yield an intermediate alkoxyl radical with α-t-butyldioxy group, which decomposes subsequently to t-butyldioxyl and methyl radicals via β-elimination. The thermal decomposition of 2,2-bis(t-butyldioxy)butane and 2,2-bis(t-butyldioxy)-3-methylbutane have also been examined. Relative rates of β-elimination of radicals from alkoxyl radicals are concluded to be isopropyl: ethyl:t-butyldioxyl: methyl=133:33:7:1, revealing a facile scission of dioxyl radical.
57Fe-Mössbauer Spectroscopic Study of Ferrocenylruthenocene, [1](1,1′)Ferroceno[1](1,1′)ruthenocenophane, and Reaction Products with Some Oxidizing Agents
Authors: Watanabe Masanobu , Sano Hirotoshi
Published: July 2006

Ferrocenylruthenocene reacts with sulfuric acid–NH4BF4 to give a mono-oxidized diamagnetic ferrocenylruthenocenium BF4− salt, while it reacts with p-benzoquinon–BF3(Et2O) to give a trioxidized paramagnetic ferrocenylruthenocenium (BF4−)3 salt. Mössbauer parameters of the former salt are very similar to those of neutral ferrocenylruthenocene, suggesting that the structure of the salt is expressed as [Cp(C5H4)Fe(II)(C5H4)CpRu(III)–Ru(III)Cp(C5H4)Fe(II)(C5H4)Cp]2+(BF4−)2 with an antiferromagnetic Ru(III)–Ru(III) bond in the solid state. Well-dissolved quadrupole splitting (Q.S.) values observed for the latter salt (e.g., 0.61mm s−1 at 4.2 K) suggest the presence of a kind of intramolecular electronic effect of a ruthenocenium moiety on the Fe(III) in the ferrocenium moiety.
Transesterification of Benzyl Phenylacetate Using Polymeric Quaternary Ammonium Salt of 1,8-Diazabicyclo[5.4.0]undec-7-ene
Authors: Ishikawa Tomomichi , Ohsumi Yasuyuki , Kawai Tadashi
Published: July 2006

When benzyl phenylacetate was treated with aqueous alcohols in the presence of polymer-attached quaternary ammonium hydroxide (PCS–DBU) prepared from l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and chloromethylated polystyrene, the transesterification to methyl phenylacetate preceded the hydrolysis to phenylacetic acid. The characterization of this PCS–DBU resin was studied by comparison with other analogous resins. It was found that the PCS–DBU resin has the highest catalytic activity and the strongest attractive affinity to the substrate among the three resins studied in this work, and plays an important role in the formation of alkoxide ions by the reaction of alohols with the hydroxide ions above the resin, in the protection of the alkoxide ions against the attack of water molecules, and in the attraction of the substrate. These effects were attributed to the specific and planar bicyclic system of the DBU, including hydrophobic long alkylene groups, in addition to the lipophilic function of polymeric skeleton. The reaction could be explained in terms of the mechanism of phase-transfer catalysis.
Solid-Phase Synthesis of Steroidogenesis-Activator Polypeptide under Continuous Flow Conditions
Authors: Nozaki Sukekatsu
Published: July 2006

4-(Hydroxymethyl)phenoxymethyl copoly(styrene–1% divinylbenzene) resin beads loosely packed in a glass column were satisfactorily employed as a solid support for synthesis of a triacontapeptide, steroidogenesis-activator polypeptide, under the Fmoc strategy. Peptide sythesis was carried out in a continuous DMF flow without generation of any considerable back pressure. Change of volume of the resin bed in the column was monitored in the course of peptide elongation. After cleavage from the resin, the product was purified on HPLC to give the desired triacontapeptide in an overall yield of 39% based on the C-terminal amino acid linked to the resin.
Unimolecular Decomposition Rate Theory at the High Pressure Limit and Its Application to the Dissociations of Methanes and Ethanes
Authors: Kodama Sukeya
Published: July 2006

A rate theory for the thermal decomposition by a single bond fission at the high pressure limit was derived from the conceptions that the equilibrium between the active molecule and the activated complex is adiabatic and that the zero point energy difference between the molecule and the complex (ΔEz\eweq) participates in the entropy term of the rate constant (kd∞) and is not related to the enthalpy term. It was also proposed a method calculating kd∞ by replacing the vibrational state sum with the entropy term. The values of kd∞ for methanes and ethanes were calculated using the present theory and the Gorin activated complex model. From good correspondences between the experimental and calculated values, the values of ΔHf,298°(CH3(g))=143.2, D0(CH3–CH3)=393.0, and D0(CH3–H)=449.1 kJ mol−1 were obtained for the standard heat of formation and the chemical bond dissociation energy. The apparent activation energy for kd∞ decreases drastically by increasing of the reaction temperature. This fact means that the estimation of thermodynamic values from the apparent activation energy is not adequate. It was also found that the vibrational temperature in the complex is considerably higher than the reaction temperature by the contribution of ΔEz\eweq mainly. This result denotes that the chemical equilibrium constant cannot be evaluated from the ratio of kd∞⁄kc∞, where kc∞ means the high pressure limiting rate constant of the radical-radical recombination reaction.
Asymmetric Synthesis of α-Amino-β-hydroxy Acids Using a Chiral Pyridoxal-Like Pyridinophane–Zinc Complex as an Enzyme Mimic; Scope and Limitation
Authors: Ando Makoto , Watanabe Jun , Kuzuhara Hiroyoshi
Published: July 2006

A chelate complex (4) with high homogeneity was precipitated upon stirring a mixture of zinc(II) ion and a Schiff base produced from glycine and (R)- or (S)-15-formyl-14-hydroxy-2,8-dithia[9](2,5)pyridinophane, chiral pyridoxal-like pyridinophane. A four-coordinated zinc chelate complex was newly proposed as the structure of 4. Aldol condensations between 4 and several aldehydes were attempted at pH 10.0. Only small linear chain aldehydes, such as acetaldehyde and propionaldehyde, could react with 4 under these conditions to give the corresponding α-amino-β-hydroxy acid in the range of 27–77% enantiomeric excess.
Computational Study of the Isomerizations and Fragmentations of the Singlet and Triplet CH2CH2NH Diradicals
Authors: Fueno Takayuki , Yamaguchi Kizashi , Kondo Osamu
Published: July 2006

Pathways for the thermal unimolecular reactions of the CH2CH2NH diradicals, both singlet and triplet, have been investigated by ab initio MO calculations using 4-31G basis functions. The minimum-energy paths for possible isomerizations and fragmentations are traced by the SCF gradient procedure, and multireference double-excitation (MRD) CI calculations carried out for all the stationary structures located. The results of calculation show that the energetically most favorable unimolecular reaction possible to the triplet diradical is an α-hydrogen detachment giving rise to CH2=CH–NH (2A″), whereas that to the singlet diradical is a 1,2-hydrogen migration to give CH3CH=NH (1A′). The activation barrier heights calculated for the two processes are 103 and 74 kJ mol−1, respectively. It is concluded that, in the gas phase, CH3CN and HCN should be formed concurrently by the α-bond cleavages of the doublet radical CH3CH=N (2A′), which will arise most readily from the vibrationally hot CH3CH=NH (1A′).
On the Reaction of N-[(3-Oxo-2-cyclohexenyl)imino]triphenylphosphorane with α-Bromo Ketones and α,β-Unsaturated Ketones
Authors: Nitta Makoto , Soeda Hironobu , Iino Yukio
Published: July 2006

The thermal reaction of N-[(3-oxo-2-cyclohexenyl)imino]triphenylphosphorane with α-bromo ketones and α,β-unsaturated ketones underwent an enamine-type alkylation and a subsequent aza-Wittig reaction to give substituted 1,5,6,7-tetrahydro-4H-indol-4-ones and 7,8-dihydro-5(6H)-quinolinones albeit in modest yields.
Transylidation of Some Stabilized Bismuthonium Ylides
Authors: Suzuki Hitomi , Murafuji Toshihiro
Published: July 2006

Triphenylbismuthonium diacylmethanides underwent the copper(I)-assisted transylidation with dimethyl sulfide and triphenylarsine in benzene at room temperature, giving the corresponding sulfonium and arsonium ylides in moderate to good yields, but they failed to exchange the ylide functionality with triphenylphosphine in most cases and with triphenylstibine in all cases examined, decomposition leading to the C– or O-phenylation of 1,3-dicarbonyl portion being the major reaction that took place.
Theoretical Investigation of van der Waals Interaction Energy of Helium Trimer. Three-Body Effect
Authors: Ichihara Akira , Itoh Reikichi
Published: July 2006

Using an ab initio configuration interaction (CI) treatment, the He trimer interaction energy for the equilateral triangular configuration was calculated. The CI included all single and double electronic excitations (SD CI). The resulting three-body component was significantly larger than the third-order perturbation calculation.
ESR Study on Free Radicals Produced from Hexane by Vacuum-Ultraviolet Photolysis, Sensitized Photolysis, and γ-Radiolysis
Authors: Koizumi Hitoshi , Yamaguchi Takehito , Yoshida Hiroshi
Published: July 2006

The free radicals generated from polycrystalline hexane at 77 K by photolysis with vacuum-ultraviolet light, sensitized photolysis, and γ-radiolysis were compared with each others using the ESR method. The selectivity of radical formation was found to depend on the excitation method.
A Convenient Preparation of 3,5-Disubstituted 1,2,4-Selenadiazoles from Primary Selenoamides by Treatment with N-Bromosuccinimide
Authors: Shimada Kazuaki , Matsuda Yoichi , Hikage Shigeki , Takeishi Yoshiyuki , Takikawa Yuji
Published: July 2006

A convenient preparation of 3,5-disubistituted 1,2,4-selenadiazoles was achieved by treatment of various primary selenoamides with N-bromosuccinimide.
Synthesis of α-Amino Acids Containing a Cyclopropane Ring via Cobalt-Catalyzed Carbonylation-Amidocarbonylation of Cyclopropanemethanols
Authors: Amino Yusuke , Izawa Kunisuke
Published: July 2006

N-Acetyl-3-cyclopropylalanine and 2-acetamido-3-cyclopropylbutyric acid were prepared under cobalt-catalyzed amidocarbonylation conditions from cyclopropanemethanol and α-methylcyclopropanemethanol, respectively. The reaction has been estimated to comprise the in situ formation of aldehyde from alcohol by cobalt-catalyzed hydrocarbonylation followed by subsequent amidocarbonylation.
Oxidation of s-Alcohols with “Oxone” in Aprotic Solvents in the Presence of Wet-Aluminium Oxide
Authors: Hirano Masao , Oose Masaki , Morimoto Takashi
Published: July 2006

The oxidation of secondary aliphatic, alicyclic, and benzylic alcohols with Oxone in aprotic solvents in the presence of “wet-aluminum oxide” afforded the corresponding ketones in good yields under mild conditions.
Manganese(III) or Cobalt(III)-Mediated Oxidative Radical Reactions of Terminal Dienes. One-Pot Synthesis of Bis(dihydrofuran)s
Authors: Nishino Hiroshi , Yoshida Tomoaki , Kurosawa Kazu
Published: July 2006

The reactions of terminal dienes such as 1,4-pentadienes and 1,5-hexadienes with tris(2,4-pentanedionato)-manganese(III) ([Mn(acac)3]) gave α,ω-bis(dihydrofuryl)alkanes (abbreviated bis(dihydrofuran)s, hereafter) in good yields. The reactions with tris(2,4-pentanedionato)cobalt(III) ([Co(acac)3]) instead of [Mn(acac)3] yielded the same bis(dihydrofuran)s quantitatively. The dienes also reacted with ethyl 3-oxobutanoate in the presence of manganese(III) acetate ([Mn(OAc)3]) or cobalt(III) acetate ([Co(OAc)3]) to produce the corresponding bis(dihydrofuran)s. The reactions of 1,3-butadienes with the manganese(III) or cobalt(III) complexes afforded only mono(dihydrofuran)s and oxidative rearrangement products, but the corresponding bis(dihydrofuran)s were not formed. The reaction of 1,5-hexadienes with ethyl hydrogen malonate in the presence of [Mn(OAc)3] did not give bis-annulated products, but mono(γ-lactone)s in moderate yields. The synthetic applications and limitations of the bis(dihydrofuran)s formation are discussed.
Stereoselective Synthesis of (E)- and (Z)-2-Alkenyltrimethylsilanes from 1,2-Epoxy-1,3-bis(trimethylsilyl)propane
Authors: Shimizu Nobujiro , Imazu Sachiko , Shibata Fumihiro , Tsuno Yuho
Published: July 2006

Stereoselective synthesis of various (E)- and (Z)-2-alkenyltrimethylsilanes (RCH=CHCH2SiMe3; R=Me, Et, n-Bu, i-Pr, c-hexyl, t-butyl, and phenyl) has been accomplished by a reaction of 1,2-epoxy-1,3-bis(trimethylsilyl)propane with Grignard reagents (RMgX) followed by subsequent Peterson olefination reactions of resulting 1,2-bis(trimethylsilyl)-3-alkanols [RCH(OH)CH(SiMe3)CH2SiMe3]; the acid (BF3OEt2 or HClO4)-catalyzed olefination yields the (E)-isomer, while the base (KH or NaH)-induced olefination yields the (Z)-isomer in more than 95% stereochemical purity in most cases.
Electrochromism of Octacyanophthalocyanine Thin Film. Investigation by Means of in situ Visible and Raman Spectroscopies
Authors: Takeshita Kimiya , Aoyama Yuko , Ashida Michio
Published: July 2006

The electrochromism of an octacyanophthalocyanine (H2Pc(CN)8) thin film was investigated by in situ visible and Raman spectroscopies in acid and alkaline electrolytes. A new absorption band was observed in the range 700–900 nm of the visible spectra during a reduction of the film. The absorbance reached a constant value at 2 F mol−1 of the cathodic electricity in an alkaline electrolyte. The Raman spectra showed a spectral change in the vibration range which is attributed to the macrocycle and the isoindole moiety; hence, the reduction seems to occur in the azaporphyrin ring. From both the visible and Raman spectra, it was revealed that H2Pc(CN)8 was protonated at the nitrogens in positions 6,13,20,27 by electrochemical reduction. The protonated H2Pc(CN)8 shows absorption in the near-infrared region in both acid and alkaline electrolytes. The mechanism for the formation of protonated H2Pc(CN)8 is considered to be analogous to that of hydrogen evolution in alkaline electrolytes. Both the visible and Raman spectra were reversible during reoxidation.
Reaction Mechanism for Ozone Oxidation of Polyethylene as Studied by ESR and IR Spectroscopies
Authors: Yamauchi Jun , Yamaoka Akiyoshi , Ikemoto Kunji , Matsui Tetsuji
Published: July 2006

In a previous study of graft copolymerization of methyl methacrylate onto polyethylene oxidized with ozone, we clarified that ozone-oxidation reactions produce peroxyl radicals in polyethylene and that the graft copolymerization is assumed to start upon heating, through the decomposition of hydroperoxides which are converted from the peroxyl radicals. A series of reaction processes proposed for the ozone oxidation were examined from the viewpoint of the reaction rate. The time–dependent content of the peroxyl radicals was pursued by observing in situ ESR; the initial evolution rate of the peroxyl radicals and the decay rate after the ozone-stop were discussed on the basis of the proposed ozone-oxidation mechanism, leading to a good agreement between the experiment and theory. The amounts of hydroperoxide and carbonyl species determined from iodometry and the IR spectra, respectively, were also discussed with regard to the oxidation time, showing reasonable linear dependences.
Structural Study of Optical Resolution. XV. Chiral Discrimination of the Facial Isomer of the Tris((R,S)-1,2-cyclohexanediamine)cobalt(III) Cation with (R,R)-Tartrate Anion
Authors: Mizuta Tsutomu , Toshitani Kazuo , Miyoshi Katsuhiko
Published: July 2006

Crystal structures of the two diastereomeric salts of the title Δ complex cation with (R,R)-tartrate anion, Δ-fac-[Co(R,S-chxn)3](ClO4)(d-tart)·mH2O (1) and Δ-fac-[Co(R,S-chxn)3]Cl(d-tart)·nH2O (2) (R,S-chxn=(R,S)-1,2-cyclohexanediamine and d-tart=dextro-rotatory (R,R)-tartrate dianion), have been determined by single crystal X-ray diffraction techniques. The former crystal 1 is orthorhombic with the space group P22121, a=12.358(3), b=22.094(5), c=32.770(7) Å, and Z=12, while the latter 2 is trigonal with the space group P3121, a=15.367(7), c=26.208(4) Å, and Z=6. In 1 are found two similar face-to-face contact modes in both of which the d-tart2− ion directs its four almost coplanar O atoms to the complex along the C3 axis, and three of them, two alcoholic and one carboxylic, are triply hydrogen-bonded to the three N–H protons on one of the triangular faces of the Δ complex denoted as the Δ-cis RRR face, where R stands for the chirality of the carbon atom adjacent to the N–H group hydrogen-bonded to the d-tart2− ion. The other triangular face of the complex denoted as the Δ-cis SSS face is so crowded that only two O atoms of the d-tart2− ion are hydrogen-bonded to the face. In 2 is found one face-to-face contact mode in which the d-tart2− ion approaches the Δ complex similarly, but the three O atoms are each placed midway between two of the three N–H protons on the triangular Δ-cis  RRR face to form three bifurcated hydrogen bonds to them, and the d-tart2− ion tactfully avoids the steric repulsion marginally by inclining its molecular plane a little relative to the triangular face at the least expense of the multiple hydrogen bonds to the face. Based on the assumption that the face-to-face contact mode found in 2 is the most probable interaction mode conceivable in solution, the elution order and separation factor obtained by ion-exchange chromatography for some related [Co(chxn)3]3+ complexes are rationally interpreted.
Application of the SPE Method to Organic Electrochemistry. XII. Lead Dioxide as a Mediator for Electrooxidation of Cinnamyl Alcohol on Pt–Nafion
Authors: Chen Zhen , Ogumi Zempachi , Takehara Zen-ichiro
Published: July 2006

Lead dioxide was examined as a mediator to oxidize cinnamyl alcohol on Pt–Nafion, and was compared with manganese dioxide. Lead dioxide was deposited into Pt–Nafion. The current efficiency for the formation of cinnamaldehyde reached 65% at room temperature, slightly lower than that in the case of using manganese dioxide. The production of cinnamic acid was more remarkable on Pb, Pt–Nafion than on Mn, Pt–Nafion because of the higher oxidation potential of the former. The mediatory action of both oxides was examined and compared with the activity in chemical oxidation using oxides produced separately. The oxidation of cinnamyl alcohol by lead dioxide was faster than that by manganese dioxide. Their mediatory action reflected their chemical activity for the oxidation.
Preparation and Characterization of Optically Active Quadridentate Schiff Base-Titanium(IV) Complexes and the Catalytic Properties of These Complexes on Asymmetric Oxidation of Methyl Phenyl Sulfide with Organic Hydroperoxides
Authors: Sasaki Caori , Nakajima Kiyohiko , Kojima Masaaki , Fujita Junnosuke
Published: July 2006

Titanium(IV) complexes, [TiCl(Schiff base)]2O, with quadridentate Schiff base ligands derived from optically active 1,2-diamines and salicylaldehyde were prepared by treating TiCl4 with an equimolar amount of the Schiff base ligand in wet pyridine. The complexes were characterized by their 13C NMR, absorption, and circular dichroism spectra, and conductivity measurements. The complexes in dichloromethane take a μ-oxo dinuclear structure, and in methanol the complexes break up into a mononuclear species, [Ti(OMe)(MeOH)(Schiff base)]Cl. The complexes catalyze the asymmetric oxidation of methyl phenyl sulfide into the sulfoxide with organic hydroperoxides; the highest enantiomeric excess (ee) was ca. 60%. The kinetics conform to a rate law which is first order in the concentration of each sulfide, hydroperoxide, and complex catalyst.
Formation of Acrylaldehyde by Vapor-Phase Aldol Condensation II. Phosphate Catalysts
Authors: Ai Mamoru
Published: July 2006

Vapor-phase aldol condensation of formaldehyde with acetaldehyde to form acrylaldehyde was studied with various oxide and phosphate catalysts using 35% formalin as the source of formaldehyde. Almost all of the tested oxides exhibited a certain activity as the catalysts. Acidic oxides, such as MoO3 and WO3 showed a relatively high selectivity to acrylaldehyde, though the activities were low. V2O5 and amphoteric oxides exhibited a much higher activity, but they promoted also the formation of CO2 and methanol. The catalytic performance was improved, to a certain extent, by combination of an acidic oxide with an amphoteric oxide. Further, the combination of phosphorus with V2O5 or an amphoteric oxide induced a large increase in the selectivity to acrylaldehyde. A good performance was obtained with the Ni–P, Mn–P, Fe–P, and V–P systems. The yield of acrylaldehyde reached 86 mol% on the AcH basis with a very slow formation of CO2 and methanol.
Spectroelectrochemistry of New Prussian Blue Films Prepared by a Cast Method
Authors: Lin Ru-Jang , Toshima Naoki
Published: July 2006

New Prussian Blue (PB) films were prepared by being cast from colloidal PB dispersions in an organic solvent containing cationic surfactants. The electrochromic behaviors of the cast PB films are similar to those of electrodeposited PB films. However, the cyclic voltammetries of both the PB films were quite different from each other. To make the difference clear, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray photospectroscopy (XPS) were used in measurements of these films grown on Pt and indium tin oxide electrodes. The EDX results for fresh PB films indicated that cast films contain K+ ions, suggesting a soluble-form PB, KFe[Fe(CN)6], while electrodeposited films do not, suggesting an insoluble-form PB, Fe4[Fe(CN)6]3. The transient spectral observations indicated the participation of a unique electrochemically active iron(III) site in the reductive cycles of a cast film, although the participation of a plural electrochemically active iron(III) sites was proposed for an electrodeposited film. After a repeated cyclic scan a cast PB film maintained its unique active site, while an electrodeposited film had plural sites comprising both a soluble and an insoluble form of PB.
The Conformational Changes of Poly(l-ornithine) with Organic Counter Ions in Aqueous Sodium 1-Decanesulfonate Solution
Authors: Aoyagi Makoto , Maeda Tamaki , Hayakawa Katumitu , Satake Iwao
Published: July 2006

The circular dichroism study was made of the coil-helix transitions of poly(l-ornithine) with 1-alkanesulfonate counter ions of the chain length from 3 to 6 in sodium 1-decanesulfonate solution. The conformational change is insensitive to the counter ion chain length and becomes appreciable even at surfactant concentrations as low as (1–2)×10−4 mol dm−3.
Electrochemical Halogenation of Trisubstituted Germanes and Silanes
Authors: Okano Mitsutoshi , Mochida Kunio
Published: July 2006

Electrochemical halogenation of trisubstituted germanes and silanes in acetonitrile occurred in the cathode compartment in contrast to the well-known electrochemical halogenations which always occur in the anode compartment.
Photolysis of Thietane and Thietane-d6 in Argon Matrix: Infrared Spectra of Matrix-Isolated Thioformaldehyde and Thioformaldehyde-d2
Authors: Watanabe Osamu , Suzuki Eiichi , Watari Fumio
Published: July 2006

Argon-matrix isolated thietane at 10 K decomposed by irradiation (λ>290 nm) to form ethylene and thioformaldehyde. The photolysis of thietane under these conditions has been shown to be a clean source of thioformaldehyde. The CH2S and CD2S molecules generated this way are indefinitely stable and their infrared spectra could be recorded.
Synthesis of Ti-Containing Pillared Montmorillonite Using a Trinuclear Acetatochlorohydroxo Titanium(III) Complex
Authors: Kijima Tsuyoshi , Nakazawa Hiromoto , Takenouchi Satoshi
Published: July 2006

Trinuclear acetato-chloro-hydroxo titanium(III) chloride, [TiIII3(OCOCH3)6.4Cl1.2(OH)0.4]Cl·11H2O, was prepared; its aqueous solution was reacted with Ca- and Cu-montmorillonites in air. Titanium(III) complex ions were mostly hydrolyzed, oxidized and condensed into their polynuclear forms, replacing the interlayer metal ions of montmorillonite. The calcined forms of both reaction products maintain large interlayer spacings of 22.2 and 21.3 Å, and have specific surface areas of 105 and 128 m2 g−1, respectively.
Syntheses and Characterization of 2,4-Dioxo-3,3-pentanediselenolato Platinum(II) Complex and Its Dithiolato Analog Prepared by Se–C and S–C Bond Cleavages of 2,3-Diseleno-1,1,4,4-tetraacetylbutane and 2,3-Dithio-1,1,4,4-tetraacetylbutane
Authors: Yamazaki Shinsaku , Ueno Tamio , Hojo Masashi
Published: July 2006

2,4-Dioxo-3,3-Pentanediselenolato(Se2-ac) platinum(II) complex [Pt(Se2-ac)(PMe2Ph)2] and its dithiolato analog [Pt(S2-ac)(PMe2Ph)2] have been prepared by treating cis-[PtCl2(PMe2Ph)2] with 2,3-diseleno-1,1,4,4,-tetraacetylbutane and 2,3-dithio-1,1,4,4-tetraacetylbutane in a KOH/acetone–methanol mixed solution. The IR, 1H, 13C, and 31P NMR and mass spectra of these complexes are discussed.
Halogenative Allylation and Reduction of Aromatic Acetals by Double Substitution of Alkoxyl Groups in Acetal
Authors: Oriyama Takeshi , Iwanami Katsuyuki , Tsukamoto Kazuhisa , Ichimura Yuichi , Koga Gen
Published: July 2006

In the presence of excessive amount of acetyl halide along with a catalytic amount of tin(II) halide, aromatic acetals react with allyltrimethylsilane or triethylsilane to give α-allylbenzyl halides or benzyl halides, respectively, in good to excellent yields.
A Convenient Synthesis of 4-(Phenylsulfonylthio)-2-azetidinones
Authors: Tanaka Hideo , Taniguchi Masatoshi , Uto Seiryu , Shiroi Takashi , Sasaoka Michio , Torii Sigeru
Published: July 2006

4-(Phenylsulfonylthio)-2-azetidinones have been prepared conveniently by the reaction of 4-(2-benzothiazolyldithio)-2-azetidinones with 2-benzothiazolyl benzenethiosulfonates. A combination of this reaction with the electrolytic cross-coupling of bis(benzothiazolyl) disulfide and ammonium benzenesulfinate can establish a recycling system, in which S-(2-benzothiazolyl) benzenethiosulfonate is regenerated to play a critical role in penicillin–cephalosporin conversions.
Reactions of 1,1-Diphenyl-2-methylpropene Cation Radicals with Methanol. Ketone Formation Involving Carbocation Rearrangement
Authors: Akaba Ryoichi , Aihara Shin , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

Anodic oxidation of 1,1-diphenyl-2-methylpropene (1) in an acetonitrile–methanol mixture under argon gave 3,3-diphenyl-2-butanone (2) in high yield together with small amounts of 1,2-diphenyl-2-methyl-1-propanone (3) and benzophenone (4). Similar anodic oxidation of 1 in the presence of oxygen was also carried out, and the mechanisms for the novel ketone forming reactions are discussed.
Studies on Some Dithiocarbamato-Bridged Heterobimetallic Complexes: Part II
Authors: Singh N K , Kaw Chetna , Singh Nanhai
Published: July 2006

Some dithiocarbamato-bridged heterobimetallic complexes of the type MI[Zn(dtc)3] and MII[Zn(dtc)3]2, (M=Co(II), Ni(II), Cu(II), Pd(II), Pb(II), Cd(II), Tl(I), Ag(I), dtc=diethyldithiocarbamate), have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility, (1H, 13C) NMR, UV-visible, and infrared spectral studies. The complexes are nonelectrolytes. The infrared spectral bands and NMR signals indicate the presence of only one type of dithiocarbamate group. The electronic spectra of the complexes recorded in chloroform, pyridine, and dimethyl sulfoxide are similar to their nujol mull spectra indicating no change in the geometry of the central metal. Magnetic moment, electronic spectra, and ESR studies are commensurate with a square-planar geometry around Co(II), Ni(II), Pd(II), and Cu(II).
Physical Characteristic and Molecular Structure of Spin-Crossover Iron(III) Complexes of Monoclinic Form with Hexadentate Ligands Derived from Triethylenetetramine and Salicylaldehyde [Fe(sal2trien)]BPli4·acetone
Authors: Maeda Yonezo , Oshio Hiroki , Tanigawa Yuichi , Oniki Takayuki , Takashima Yoshimasa
Published: July 2006

Iron(III) complexes of [FeL]BPh4·acetone containing the hexadentate ligand derived from triethylenetetramine and salicylaldehyde have been synthesized. These complexes were grown in two crystalline forms, monoclinic and the twin crystals. The crystal structure of the monoclinic form was determined at 290 K, at which temperature the complex is in a transition spin-state between high- and low-spin states; the spin-state interconversion rate of the monoclinic form is as fast as the inverse of the Mössbauer lifetime (1×10−7s) above 200 K. The monoclinic crystal of [FeL]BPh4·acetone is of space group P21⁄a, with a=27.418(4), b=10.097(2), c=14.726(3) Å, β=98.00(1)°C, and Z=4. The average bond distances of Fe–O (1.875 Å), Fe–Nimine (1.988 Å), and Fe–Namine (2.069 Å) are in good agreement with the expected values for the transition spin-state between high- and low-spin states. Twin crystals are in a high-spin state over the temperature range 78–320 K.
Structure of Cobalt(II) Ion and Tri- and Tetrachlorocobaltate(II) Complexes in N,N-Dimethylformamide Determined by the Fluorescent EXAFS Method
Authors: Ozutsumi Kazuhiko , Tohji Kazuyuki , Udagawa Yasuo , Ishiguro Shin-ichi
Published: July 2006

EXAFS (extended X-ray absorption fine structure) spectra were measured for N,N-dimethylformamide (DMF) solutions containing cobalt(II) ion and its chloro complexes of low concentration (20–40 mmol dm−3) by a laboratory EXAFS spectrometer modified for the fluorescence detection. The analysis of the EXAFS data for a cobalt(II) perchlorate DMF solution showed that cobalt(II) ion in DMF has an octahedral structure with six DMF molecules. The Co-O (DMF) bond length within [Co(dmf)6]2+ in DMF is 206(1) pm and is practically the same as that within [Co(H2O)6]2+ (208 pm) in water within experimental uncertainties. It was also shown that the tri- and tetrachlorocobaltate(II) complexes in DMF have a tetrahedral structure. The Co–O and Co–Cl lengths within [CoCl3(dmf)]− in DMF are 202(1) and 227(1) pm, respectively. The Co–Cl distances within [CoCl]2− in DMF and in water are the same and 229(1) pm.
Mechanism of Cis–Trans Isomerization of Fluoranthenylethylenes on Direct Irradiation
Authors: Furuuchi Hideo , Kuriyama Yasunao , Arai Tatsuo , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

On direct irradiation 8-styrylfluoranthene (SF) and 8-(3,3-dimethyl-1-butenyl)fluoranthene (BF) underwent two-way and one-way isomerizations, respectively, in the triplet manifold after intersystem crossing of the initially produced singlet excited state.
Combustion Reactions in Methane–Air Premixed Flames
Authors: Fukutani Seishiro , Sakaguchi Keizo , Kunioshi Nílson , Jinno Hiroshi
Published: July 2006

A reaction scheme reproducing methane combustion by computer simulation under a wide range of stoichiometric ratio has been proposed and applied to flat methane–air premixed flames to elucidate factors determining their propagation mechanisms and the role of C2 reaction pathways. Main methane combustion reactions, which progress sequentially from the fuel to carbon dioxide, are inhibited at low temperatures due to retarded production of oxygen atoms which are necessary for the oxidation of methyl radicals. The role of C2 routes have been investigated by comparison of the results obtained by use of the C2 scheme and a simplified C1 scheme. Some of the methyl radicals are once recombined to ethane but most of the produced ethane is dissociated again to methyl via ethyl radicals. Then the C2 routes work as a temporary storage of species and hinder the main combustion reactions which go through C1 species.
Increase of Solvent-Soluble Products of Coal by Repeated Butylation with Zinc and Butyl Iodide under Mild Conditions
Authors: Yoneyama Yoshiharu , Yamamura Yutaka , Hasegawa Kiyoshi , Kato Tsutomu
Published: July 2006

Yubari and Taiheiyo coals were repeatedly butylated with zinc metal powder and butyl iodide under mild conditions. After the benzene-soluble products (BS) from each reaction were combined the mixture was further butylated. The BS and its butylation products (Bu.BS) were fractionated by gel permeation chromatography. At each reaction step, BS with a similar structural character but different degrees of polymerization were solubilized for Taiheiyo coal; for Yubari coal BS with similar characteristics were solubilized. A large portion of these Bu.BS from both coals were solubilized in hexane. The molecular weight of BS decreased after butylation. These results suggest that this procedure brings about depolymerization as well as the introduction of butyl groups, while enhancing solubilization.
Hydroformylation–Amidocarbonylation of Methylvinylphosphinate. Application to Synthesis of Glufosinate
Authors: Sakakura Toshiyasu , Huang Xin-Yan , Tanaka Masato
Published: July 2006

Glufosinate, 2-amino-4-[(hydroxy)methylphosphinyl]butanoic acid, (2a) was synthesized from 2-chloroethyl methylvinylphosphinate (1a) via successive hydroformylation–amidocarbonylation. Hydroformylation of 1a catalyzed by Co2(CO)8 in methanol gave 2-chloroethyl (3,3-dimethoxypropyl)methylphosphinate (5). Crude 5 was subjected to cobaltcatalyzed amidocarbonylation to afford N-acylglufosinic acid methyl ester (2b). Hydrolysis of 2b under acidic conditions gave 2a quantitatively.
Thermal Properties of Liquid-Crystalline Polyitaconates with Paired Mesogens
Authors: Sugiyama Kazuo , Shiraishi Kohei
Published: July 2006

2-Methylenesuccinates (Itaconates) (2) having two 4-methoxyazobenzene moieties as paired mesogenic groups were prepared. The monomer 2 was radically homopolymerized and copolymerized with non-mesogenic monomer, dioctadecyl itaconate (DOI). Paired mesogenic homopolyitaconate exhibits a nematic phase and the copolymers of the monomer 2 with DOI also show a mesomorphic phase up to 25 mol% of DOI content. The enhancement of mesophase formation by paired mesogens is discussed.
Formation of 1,2-Dioxanes by the Use of Tris(2,4-pentanedionato)manganese(III) or Manganese(III) Acetate
Authors: Nishino Hiroshi , Tategami Shin-ichi , Yamada Takashi , Korp James D , Kurosawa Kazu
Published: July 2006

The reactions of 1,1-diphenylethene, 1,1-bis(4-chlorophenyl)ethene, 1,1-bis(4-methoxyphenyl)ethene, 1,1-bis(4-methylphenyl)ethene, 1,1-bis(4-fluorophenyl)ethene, styrene, 1-octene, cyclohexene, and cyclooctene with tris(2,4-pentanedionato)manganese(III) ([Mn(acac)3]) in acetic acid at room temperature give 4-acetyl-3-methyl-1,2-dioxan-3-ol in 8–92% yields, together with 3-acetyl-4-hydroxy-3-hexene-2,5-dione. The similar reactions of 1,1-diphenylethene with 2,4-pentanedione, 3-methyl-2,4-pentanedione, 3-ethyl-2,4-pentanedione, 1-phenyl-1,3-butanedione, acetoacetanilide, and 1,3-cyclohexanedione in the presence of manganese(III) acetate also give the corresponding cyclic peroxide in good to moderate yields. The mechanisms of manganese(III)-induced 1,2-dioxane ring formation and concomitant radical side reaction are discussed.
Alkynylations of Oxiranes with Lithium Acetylides by the Catalysis of Trimethylgallium
Authors: Fukuda Yukitoshi , Matsubara Seijiro , Lambert Claude , Shiragami Hiroshi , Nanko Toshiki , Utimoto Kiitiro , Nozaki Hitosi
Published: July 2006

The reaction of 1-lithio-1-alkynes with oxiranes under the catalytic action of trimethylgallium afforded the corresponding β-hydroxy acetylenic compounds in good yields with excellent regioselectivities. No isomerization of oxiranes was observed during the reactions because of low Lewis acidity of trimethylgallium. The mechanism including activation of an oxirane by the coordination to trimethylgallium was proposed.
Kinetic Studies of Electron-Transfer Reactions Induced by the Reductive Quenching of Tris(2,2′-bipyrazine)ruthenium(II)
Authors: Yamazaki-Nishida Suzuko , Kimura Masaru
Published: July 2006

The oxidation reaction of the oxalate ion (C2O42−) by the peroxodisulfate ion (S2O82−) is greatly accelerated by irradiation with visible light in an aqueous solution containing tris(2,2′-bipyrazine)ruthenium(II) ([Ru(bpz)3]2+). The mechanism constitutes a chain reaction initiated by a reductive quenching of photoexcited [Ru(bpz)3]2+ with C2O42−. The rate of reaction increases with an increase of the [Ru(bpz)3]2+ concentration or incident light intensity. On the other hand, the reaction rate hardly depends not only on the concentrations of C2O42− and S2O82−, but also on the ionic strength and temperature. The [Ru(bpz)3]2+ acts as a photo-catalyst, although the absorption spectra of the reaction solution are slightly changed during the photoreaction. An analysis of the absorption spectra by a graphic method indicates that another absorbing species than [Ru(bpz)3]2+ is formed in the reaction solution. Such a complex has no photocatalytic effect for the redox reaction between S2O82− and C2O42−. The concentration of the produced complex is always coincident with ca. 0.7% of that of the S2O82− reacted. The reaction mechanism and rate law are clarified to account for the results obtained.
The Intercalation of n-Alkylamines into Layered Transition Metal Phosphates-Solvent Effect
Authors: Kanzaki Yasushi , Abe Mitsuo
Published: July 2006

The intercalation of n-alkylamines (carbon number 1–18) into γ-titanium phosphate and γ-zirconium phosphate was examined in aqueous, methanol, and benzene solutions. The interlayer spacings increased with an increase in the carbon number of alkylamines, showing the formation of bilayers of alkylamines in a similar manner to that in previous reports. The intercalation reaction depended on the solvents used to dissolve the alkylamines. For example, an anomaly was observed regarding intercalation in ethanol solutions. The interlayer spacings decreased when the carbon number exceeded 14–16, indicating a distortion or the monolayer formation of alkylamines. The rate of intercalation was also seriously affected by the kind of solvents. Intercalation occurred almost instantaneously in aqueous solutions. The rate of the intercalation reaction was generally faster in benzene solutions than that in ethanol solutions. The formation of bilayers was also more perfect in benzene solutions, and resulting interlayer spacings were slightly larger than those prepared in ethanol solutions. The anomaly in ethanol was attributed to a disturbance due to the cointercalation of methanol molecules. The solvent effect was also accountable due to the dielectric constant, or dipole moment, of solvents.