bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamic Stability of β-Chloro-, β-Phenylthio-, and β-Phenylamino-Substituted α,β and β,γ-Unsaturated Ketones
Authors: Sugita Toshio , Gohda Katsura , Kagiya Tsutomu 
Published: July 2006

Abstract
Acid-catalyzed chemical equilibration studies on the titled compounds have been carried out. The β,γ-isomers are highly favored at equilibrium in the cases of β-chloro- and β-phenylthio-substituted ketones. Hydrogen-bonding between carbonyl oxygen and sulfonium or amine proton stabilizes the α,β-unsaturated form.
Chemical Evolution, Biosynthesis, and Aromaticity
Authors: Aihara Jun-ichi 
Published: July 2006

Abstract
Naturally occurring heterocycles such as imidazole and thiophene do not conform to the rule of topological charge stabilization. Abiotic synthesis and biosynthesis of such heteroconjugated molecules can be rationalized in terms of aromatic stabilization. Antiaromatic molecules are formed neither in primitive-Earth-simulation experiments nor in living systems.
The Intrinsic Equilibrium Constants of the Surface Hydroxyl Groups of Maghemite and Hematite
Authors: Watanabe Haruo , Seto Jun’etsu 
Published: July 2006

Abstract
The intrinsic equilibrium constants of the surface hydroxyl groups, which describe the ionization of surface hydroxyl groups and the complexation of ions of a KCl electrolyte, were calculated with the surface charge densities determined by the potentiometric titration, and with the surface site densities evaluated by the surface hydroxyl group densities. The values of the intrinsic ionization constants, Kalint and Ka2int of maghemite, are higher than those of hematite, and the differences of these values have a tendency for ΔpKalint&lt;ΔpKa2int The values of the intrinsic complexation constants, *KK+int and *KCl-int, of maghemite are higher than those of hematite. These results could be attributed to the differences of the electron densities of the oxygen atoms of the surface hydroxyl groups, which are linked to those in the bulk those of maghemite are lower than those of hematite. Also, the differences become smaller with increasing number of bonding protons.
Mesophase Pitch Derived from Isotropic Anthracene Pitch Produced Catalytically with HF/BF3
Authors: Mochida Isao , Shimizu Kiyoyuki , Korai Yozo , Sakai Yukio , Fujiyama Susumu 
Published: July 2006

Abstract
The thermal preparation of the mesophase pitch from the isotropic anthracene pitch produced catalytically from anthracene with HF/BF3 was studied through both single- and two-stage heat-treatments. The single stage under vacuum provided a mesophase pitch (SMAP-2) of 100% anisotropy and excellent spinnability at yield as high as 59%. The present mesophase pitch maintained the naphthenic structure to some extent, although thermal preparation, which tends to induce dehydrogenative aromatization, was employed. The two-stage preparation, comprising heat-treatments under pressure (2.1 MPa) and then under vacuum (1 Torr, 1 Torr≈ 133.322 Pa) increased the yield of the mesophase pitch to 64%. The resultant mesophase pitch (TMAP) of 100% anisotropy and excellent spinnability carried fewer aliphatic groups than that of the single stage. SMAP-2 was sufficiently stabilized for 30 min at 300 °C, superior to that of the mesophase pitches derived from FCC-DO and the isotropic naphthalene pitch. The complete stabilization of TMAP with a smaller aliphatic structure was achieved within a slightly longer time of 45 min. The number of aliphatic groups is closely related to the stabilization reactivity. It is worth noting that the present mesophase pitches prepared from the isotropic anthracene pitch retained the structure of the starting pitch to an extent which depended on the procedure, influencing the stabilization reactivity.
Stereochemistry in Nucleophilic Vinylic Substitution of Activated Nitro Olefins
Authors: Park Kyong Pae , Ha Hyun-Joon 
Published: July 2006

Abstract
Each of E and Z-isomers of activated α,β-dinitro olefins and α-iodo-β-nitrostilbene reacted ith several different types of nucleophiles such as amines, thiocyanate, and p-toluenethiolate. Only Z-isomers of vinylic-substituted olefins with amines and thiocyanate were observed as products due to the attractive interactions between the nitro group of substrate and the nucleophile in the intermediate state. p-Toluenethiolate as a nucleophile could not interact strongly enough to yield a single Z-product but a converged (E) and (Z) mixture of products. Still, preference is toward Z-configuration.
Nickel-Catalyzed Dehydrogenation of Amines to Nitriles
Authors: Yamazaki Shigekazu , Yamazaki Yasuyuki 
Published: July 2006

Abstract
Aliphatic primary amines having α-methylene underwent oxidative dehydrogenation on treatment with NiSO4 as a catalyst and K2S2O8 as an oxidant to give the corresponding nitriles in good yields. Benzhydrylamine was converted to benzhydrylideneamine quantitatively under the same reaction conditions.
Papain-Catalyzed Hydrolysis of N-Protected Glycosylated Amino Acid Ester
Authors: Ishii Hiroshi , Funabashi Kazuyoshi , Mimura Yoshimasa , Inoue Yoshio 
Published: July 2006

Abstract
The selective hydrolysis of α-methyl ester of glycosylated amino acid derivative, Boc–Asn(NAcGlc)–OMe, was achieved by using papain. Optimal conditions for hydrolysis were estimated.
Molecular Design of Crown Ethers. VII. Syntheses and Cation Selectivities of Unsubstituted 12- to 16-Crown-4
Authors: Liu Yu , Inoue Yoshihisa , Hakushi Tadao 
Published: July 2006

Abstract
Solvent extraction of aqueous alkali and some heavy metal picrates with the title compounds showed that, with most cations except for Li+, Na+, and Ag+, the extractability decreases monotonically as the ring size increases from 12 to 16. However, 14-crown-4 showed the highest extractability and selectivity for Li+ over the larger alkali metals, while 15-crown-4 exhibited the highest Ag+/TI+ selectivity.
Phenylcycloheptabenzofuran from (2-Phenoxyphenyl)phenylcarbene and Its Photoisomerization
Authors: Tomioka Hideo , Murata Hiroshi , Murata Shigeru 
Published: July 2006

Abstract
Photolysis (&gt;350 nm) of (2-phenoxyphenyl)phenyldiazomethane (1)in cyclohexane at 10 °C gave the title compound (4), while similar irradiation with a shorter wavelength light (&gt;300 nm) afforded a mixture of the isomers (5–7), which were shown to be formed by photoisomerization of the initially formed 4.
Acid-Catalyzed Cleavage of Methoxymethyl Phenyl Sulfoxide. Solvent Effects and Mode of Bond Cleavage
Authors: Okuyama Tadashi , Fueno Takayuki 
Published: July 2006

Abstract
Rate constants for the acid-catalyzed hydrolysis of methoxymethyl phenyl sulfoxide increase with increasing composition of dioxane in aqueous dioxane solution in contrast to the isomeric sulfenate which is strongly decelerated by added dioxane fraction (up to 90 vol%). The isotope distribution in the products obtained from the [18O]-sulfoxide was examined in 95 vol% aqueous dioxane. About 90% of the 18O was retained in the product S-phenyl benzenethiosulfinate from the reaction with hydrochloric and hydrobromic acid while only 50–60% of the 18O was found in the thiosulfinate from the reaction with perchloric acid. A plausible reaction mechanism involving ligand coupling within a hypervalent intermediate is proposed for the partial loss of the 18O label in the latter reaction.
ESR Spectra of the Radical Anions of Nitrobenzene and p-Nitrobenzoic Acid Incorporated into Micelles
Authors: Kubozono Yoshihiro , Aoyagi Makoto , Ata Masafumi , Gondo Yasuhiko 
Published: July 2006

Abstract
The radical anions of nitrobenzene and p-nitrobenzoic acid have been prepared chemically for the first time in aqueous solutions with the aid of micelles. The radicals thus prepared are stable and the resulting ESR spectra are unsymmetrical owing to the suppressed rotational diffusion of the radicals due to incorporation into micelles. The environments surrounding the radicals are discussed in terms of the 14N hyperfine coupling constants and the rotational correlation times. For p-nitrobenzoic acid radical anion, the temperature dependence of the ESR spectrum has been studied.
Hindered Internal Rotation Around the C–N Bond in 1H-Azepine Derivatives as Studied by the NMR Techniques
Authors: Itoh Shuji , Yokoyama Yukihiro , Okumoto Takashi , Saito Katsuhiro , Takahashi Kensuke , Satake Kyosuke , Takamuku Hiromi , Kimura Masaru , Morosawa Shiro 
Published: July 2006

Abstract
Thermodynamical parameters for the restricted rotation of seven title derivatives have been obtained by means of DNMR techniques. The results were explained in terms of a conjugation of the nitrogen atom in the seven-membered ring with the adjacent carbonyl carbon.
Elucidation of Shimura’s Reduction Parameter for the First Ligand Field Band Components of Cobalt(III) and Chromium(III) Mixed Ligand Complexes
Authors: Kaizaki Sumio 
Published: July 2006

Abstract
Elucidation was made for Shimura’s recently proposed reduction parameter, which enables us to improve the prediction of the first absorption band components from Yamatera’s rule, in terms of the angular overlap model(AOM) parameterization for cobalt(III) and chromium(III) mixed ligand complexes. From the configuration interaction between the degenerate components and in view of the empirical relation for the eσa and eσb AOM parameters as revealed recently in the nondegenerate component of trans-[Cra4b2] type complexes, Shimura’s empirical reduction parameter α was elucidated semiquantitatively in relation with the difference between the eσ parameter values for the a and b ligands, Δ′σb=3(eσb−eσa); the larger the Δ′σb the smaller the reduction parameter α, and vice versa.
Kinetic Studies on the Reactions of Electrogenerated 9,10-Diphenylanthracene Cation Radical with Water and Alcohols by Means of Column-Electrolytic Stopped-Flow Method
Authors: Oyama Munetaka , Nozaki Koichi , Nagaoka Tsutomu , Okazaki Satoshi 
Published: July 2006

Abstract
The reactions of 9,10-diphenylanthracene cation radical (DPA+·) with water and alcohols in acetonitrile (AN) were studied using a novel column-electrolytic stopped-flow spectrophotometric method. The reaction was first-order with respect to DPA+· in all reactions. The reaction orders of other reactants were determined by plotting the logarithms of the apparent first-order rate constants (kapp’s) against the logarithms of the concentration of reactants. The plot of logkapp vs. log [alcohols] was linear, and hence the reaction was clearly determined to be second-order. On the other hand, the logkapp vs. log [water] plot did not show a linear relationship. Similar results were obtained in the reactions of 9,10-dimethylanthracene cation radical with water and methanol. Comparing the results obtained with water and alcohols, and considering the changes in the physicochemical properties of the AN–water medium, it was concluded that the reaction of water was second-order, though it had been believed previously to be first-order. Products of the reactions are trans- and cis-9,10-dialkoxy-9,10-diphenyl-9,10-dihydroanthracene in many cases.
Photolysis of Triphenylacetic Acid and Its Methyl Ester: A Novel Photochemical Generation of Carbene Intermediates
Authors: Shi Min , Okamoto Yoshiki , Takamuku Setsuo 
Published: July 2006

Abstract
The photolysis of methyl triphenylacetate in methanol gave biphenyl, methyl α-methoxyphenylacetate, methyl benzoate, and methoxydiphenylmethane. The formation of these products suggests that two types of α,α-elimination take place: One is the elimination of two phenyl groups leaving Ph–\"{C}–CO2Me (type a), and the other is the elimination of the phenyl and methoxycarbonyl groups generating Ph2C: (type b). Only type a elimination was efficiently quenched by oxygen.
The Partial Oxidation of Ethane over a B2O3–Al2O3 Catalyst
Authors: Murakami Yasushi , Otsuka Kiyoshi , Wada Yuji , Morikawa Akira 
Published: July 2006

Abstract
The catalytic activities were examined for the partial oxidation of ethane over various metal oxides. B2O3(30wt%)-added Al2O3 showed the highest catalytic activity in the formation of acetaldehyde (yield: 1.03%) and ethylene (14.6%). Ethylene and acetaldehyde are assumed to be formed via a common reaction intermediate because of the similarity in their kinetic behavior and the similar activation-energy values observed. The second-order dependence of the formation rates for the two products on the pressure of ethane suggests that the two molecules of ethane participate in the formation of the intermediate in the chain reaction mechanism proposed. The active site for the formation of acetaldehyde from the intermediate is suggested to be a highly dispersed boron electron-donated from alumina, but that for ethylene must be different from that of acetaldehyde.
Coordination Selectivity in the Reaction of Iron(II) with 8-Hydroxy-7-(8-quinolyl)azo-5-quinolinesulfonic Acid
Authors: Noritake Masaki , Okamoto Ken-ichi , Hidaka Jinsai , Einaga Hisahiko 
Published: July 2006

Abstract
The formation of an iron(II) complex with 8-hydroxy-7-(8-quinolyl)azo-5-quinolinesulfonic acid (QHQS,H2qhqs) has been investigated on the basis of the electronic absorption spectra, the equilibrium, and the stopped-flow kinetics in a 0.10 mol dm−3 aqueous sodium chloride solution at 25°C with a view to elucidating the coordination selectivity of the ligand. A 1:2 (metal:ligand) complex forms in an acidic medium with a selective coordination of QHQS to iron(II), with its 2-(8-quinolylazo)phenol moiety acting as a terdentate ligand. The complex formation reaction proceeds through a single pathway of Fe2+ with Hqhqs−, a ligand species singly protonated at the phenolate oxygen, with the rate constant (k21) of k21=(3.16±0.20)×105 mol−1dm3s−1, to form a mono-ligand complex as the rate-determining step. The coordination of the ligand by 8-quinolyl nitrogen, followed by a rate-determining bonding of phenolato oxygen, was suggested as the reaction mechanism.
Kinetics and Mechanism of Oxidation of Phosphinic, Phenylphosphinic, and Phosphonic Acids by Pyridinium Chlorochromate
Authors: Seth Monila , Mathur Abha , Banerji Kalyan K 
Published: July 2006

Abstract
Oxidation of the lower oxyacids of phosphorus by pyridinium chlorochromate (PCC) results in the formation of the corresponding higher oxyacids of phosphorus. The reaction is of first order with respect to PCC and the oxyacid. The reaction is catalyzed by hydrogen ions, kobs=a+b[H+]. The reaction exhibited a substantial primary kinetic isotope effect. The rates in 19 different organic solvents have been analyzed using Kamlet–Taft’s and Swain’s equations. It has been found that the cation-solvating power of the solvents plays a predominant role. It is proposed that the “inactive” tautomer of the phosphorus oxyacids is the reactive species. Transfer of a hydride ion from the P–H bond to PCC, in the rate-determining step, has been proposed.
Tris(2,2′-ipyridine)ruthenium(II) in Sodium Dodecyl Sulfate-γ-Alumina Hemimicelles. Enhanced Electron Transfer and Exchange Hemimicellization with 1,1′-Dimethyl-4,4′-Bipyridinium
Authors: Sato Hiroyasu , Kasatani Kazuo 
Published: July 2006

Abstract
On addition of 1,1′-dimethyl-4,4′-bipyridinium (methyl viologen, MV2+) to tris(2,2′-bipyridine)ruthenium(II) (R2+) solubilized in sodium dodecyl sulfate (SDS)-γ-alumina hemimicelles (HM), an effective quenching due to electron transfer occurs in HM. Addition of a large amount of MV2+ expels R2+ out of HM into the aqueous phase, as a result of exchange hemimicellization.
Synthesis and Enantiomer Recognition of the 18-Crown-6 Derivative Containing Two Tert-Butyl Substituents as a Chiral Barrier
Authors: Naemura Koichiro , Ueno Michi 
Published: July 2006

Abstract
The optically active 18-crown-6 derivative having two tert-butyl substituents as a chiral barrier was prepared by using (−)-(R)-3,3-dimethylbutane-1,2-diol as a chiral source and its chiral recognition behavior in transport of racemic guest molecules through bulk liquid membranes was investigated.
New Preparative Method of Fine Powder of Yttrium(III) Oxide by Thermal Decomposition of NH4Y(C2O4)2· H2O Fine Crystal Obtained by Reaction of a Strongly Acidic Solution of Yttrium Oxalate and an Aqueous Ammonia Solution
Authors: Minagawa Yukinori , Yajima Fumikazu 
Published: July 2006

Abstract
A fine powder of yttrium(III) oxide has been obtained by calcination of a quasi-stable salt of NH4Y(C2O4)2· H2O, which was prepared by the rapid addition of an aqueous ammonia solution into a strongly acidic yttrium oxalate solution. The particle size distribution weakly depends on the addition time of the aqueous ammonia solution and the agitation speed, and strongly depends on the washing times with pure water and on the calcination temperature of NH4Y(C2O4)2· H2O crystal. The precipitation mechanism of NH4Y(C2O4)2·H2O is discussed in terms of kinetics in the solution.
Formose Reactions. XXVIII. Selective Formation of 2,4-Bis(hydroxymethyl)-3-pentulose in N,N-Dimethylformamide–Water Mixed Solvent
Authors: Shigemasa Yoshihiro , Ueda Takaaki , Saimoto Hiroyuki 
Published: July 2006

Abstract
Dihydroxyacetone, Dl-glycero-tetrulose, and 2,4-bis(hydroxymethyl)-3-pentulose (2,4-BH-3-P) were favorably formed in a formose reaction by choosing a suitable ratio of water to N,N-dimethylformamide used as solvent or a suitable [thiamine·HCl]/[HCHO] ratio. The formose reaction was strongly affected by the concentration of formaldehyde in the water layer. Under the reaction conditions studied, thiamine decomposed rapidly. 2,4-BH-3-P was isolated from the reaction mixture and characterized by MS, IR, and NMR techniques. A pathway for the formation of 2,4-BH-3-P was also proposed.
An Efficient and General Method for the Reformatsky-Type Reaction of Chlorodifluoromethyl Ketones with Carbonyl Compounds Giving α,α-Difluoro-β-hydroxy Ketones
Authors: Kuroboshi Manabu , Ishihara Takashi 
Published: July 2006

Abstract
Chlorodifluoromethyl ketones CF2ClCOR, where R is an alkyl, aryl, and 1-alkynyl group, underwent the Reformatsky-type aldol reaction with a wide variety of aldehydes or ketones in the presence of acid-washed zinc dust and copper(I) chloride or silver acetate to give the corresponding α,α-difluoro-β-hydroxy ketones in good to excellent yields. Specific activation of zinc metal with the metal salt is essential to achieve high efficiency of the reaction, depending upon the structures of the chlorodifluoromethyl ketones and the carbonyl compounds employed. In-situ formed intermediates in these reactions were successfully detected by 19F NMR spectroscopy, which suggests that their structure is not an α-metallo ketone but an oxygen-metallated species possessing the zinc(II) metal as counter cation.
Palladium Catalyzed Direct Oxidation of Benzene with Molecular Oxygen to Phenol
Authors: Jintoku Tetsuro , Takaki Ken , Fujiwara Yuzo , Fuchita Yoshio , Hiraki Katsuma 
Published: July 2006

Abstract
Direct phenol synthesis from benzene is currently one of the most important problems in modern chemistry. We have reported new phenol synthesis from benzene and O2 via direct activation of a C–H aromatic bond by the Pd(OAc)2/phenanthroline catalyst system. The evidence for direct oxidation of benzene by O2 was obtained using 18O and 2H isotopes. The mechanism was proposed on the basis of these results and the reactions of Ph–Pd σ complex intermediates.
The Hydroboration of 1-Alkylthio-l-alkynes, and Its Application to the Syntheses of S-Alkyl Alkanethioates and (Z)-1-Alkylthio-1-alkenes
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira 
Published: July 2006

Abstract
Hydroboration of 1-alkylthio-1-alkynes with dicyclohexylborane or bis(1,2-dimethylpropyl)borane proceeded smoothly, adding most of the dialkylboryl group to the α-position of the triple bond. The resulting alkenylboranes afforded either S-alkyl alkanethioates on a controlled oxidation with alkaline hydrogen peroxide in the presence of N,N,N′,N′-etramethylethylenediamine or (Z)-1-alkylthio-1-alkenes on a basic protonolysis, successive treatments with methyllithium, copper(I) iodide and water in the presence of hexamethylphosphoric triamide.
Oxidation and Reduction Potentials and Electron-Transfer Interactions in Photoexcited States
Authors: Kubota Tanekazu , Uno Bunji , Kano Kenji , Kawakita Toshio , Goto Masashi 
Published: July 2006

Abstract
In this paper we discuss the oxidation and reduction potentials of a solvated redoxcouple in photoexcited states, these being the extension of our foregoing theoretical treatment pertinent to the energetics of sequential electrooxidation (E1⁄2oxd) and reduction (E1⁄2red) steps. After formulating the ionization potential and electron affinity of solvated molecules by using the E1⁄2oxd and E1⁄2red values, the equations on the oxidation (E1⁄2·excoxd) and reduction (E1⁄2·excred) potentials in excited states are derived. From these the important relation (E1⁄2·excoxd+E1⁄2·excred)=(E1⁄2oxd+E1⁄2red) obtained. For the case of a benzenoid alternant hydrocarbon (BAH) the above left-hand-side summation would become constant. Also, the mutual correlation of the E1⁄2·excoxd or E1⁄2·excred value at 1La excited state to the E1⁄2·excred or E1⁄2·excoxd potential at ground state is discussed for BAH’s. Finally the electron-transfer interaction between an electron donor and an electron acceptor has been considered in photoexcited states by virtue of oxidation and reduction potentials. The equation thus obtained is of the same type as that formulated semiempirically by Rehm and Weller. Our treatment provides theoretical background for the Rehm and Weller equation.
Graphite Furnace Atomic Absorption Spectrometric Determination of Bismuth(III) after Coprecipitation with Hafnium Hydroxide
Authors: Ueda Joichi , Takagi Midori 
Published: July 2006

Abstract
A method for the coprecipitation of bismuth(III) with hafnium hydroxide followed by a graphite-furnace atomic absorption spectrometric determination is described. Hafnium hydroxide coprecipitates quantitatively 0.05–3 μg of bismuth(III) from 50–400 cm3 of sample solution at pH 5.8–11.2. The presence of 2.5–50 mg of hafnium in 25 cm3 does not affect the atomic absorbance of bismuth(III). The calibration curve is linear for 0.05–3 μg of bismuth(III) in 25 cm3 and passes through the origin. Interference from the presence of large amounts of silver can be eliminated by removing silver as the ammine complex produced by the coprecipitation procedure at above pH 11 with aqueous ammonia. Several other matrix ions investigated do not interfere with the determination in at least a 500-fold mass ratio to bismuth(III). This method was successfully applied to the determination of trace bismuth(III) in commercial metal silver (purity: 99.99%), and is also applicable to the determination of trace amounts of bismuth(III) in water sample.
Reducibility of Metal Oxides in Hydrogen and Strength of Oxygen Bond in Their Surface Layer
Authors: Klissurski D , Dimitrova R 
Published: July 2006

Abstract
A distinct correlation between the reducibility of metal oxides in hydrogen and the strength of the oxygen bond in their surface layer has been found. Simultaneously it has been shown that the widely accepted concept for a correlation between the melting points of oxides and their reducibility needs a critical reconsideration.
Cooperation of Imidazolyl and Carboxylate Residues for Efficient Cleavage of Bis(nitrophenyl) Hydrogenphosphates
Authors: Komiyama Makoto 
Published: July 2006

Abstract
4-Imidazoleacetate efficiently catalyzes the cleavage of bis(2,4-dinitrophenyl) hydrogenphosphate and bis(4-nitrophenyl) hydrogenphosphate (1600 and 15000 fold acceleration at pH 8.0 at 1.0 mol dm−3). The effective catalysis is ascribed to the intramolecular cooperation of the imidazolyl and the carboxylate residues.