bluuebunny/crossref_metadata_2025_split huggingface dataset:
N-Acylimidazoles–Trifluoroacetic Acid System as the Acylating Agent for Aromatic Hydrocarbons
Authors: Keumi Takashi , Saga Hiroshi , Kitajima Hidehiko 
Published: July 2006

Abstract
N-Benzoylimidazole in trifluoroacetic acid could benzoylate electron-rich aromatic compounds, such as durene, p-dimethoxybenzene, mesitylene, anisole, thiophene, and fluorene, to give the corresponding benzophenone derivatives in good yields. It was further elucidated, in the reaction of fluorene, that N-acylimidazoles composed of a variety of acyl groups also could be used for the ketone synthesis. Therein, the imidazolides of aliphatic carboxylic acids or substituted benzoic acids with an electron-donating group gave ketones in high yields. The above-mentioned aromatic compounds were also acylated with N-trifluoroacetylimidazole and free carboxylic acids in trifluoroacetic acid. The mechanism for these reactions was assumed to proceed via a mixed anhydride between trifluoroacetic acid and carboxylic acid.
Layered Compounds. LXIII. Bromination of Double- and Triple-layered Paracyclophanes
Authors: Otsubo Tetsuo , Horita Hisanori , Koizumi Yosuke , Misumi Soichi 
Published: July 2006

Abstract
[m.m][n.n]Triple-layered paracyclophanes underwent bromination to give exclusively monobromo derivatives substituted to the inner benzene. The reactions were markedly accelerated by the transannular electronic interaction as compared to [n]- and double-layered paracyclophanes, and their enhanced reactivities were demonstrated by some competitive reactions. The relative rates of [2.2] and [3.3]systems are in reverse order for the triple-layered and double-layered series. Their reaction mechanisms were discussed.
The Synthesis of Unsubstituted Crown Ethers by the Reaction of Oligoethylene Glycols with Arenesulfonyl or Alkanesulfonyl Chlorides
Authors: Kuo Ping-Lin , Kawamura Norio , Miki Masaki , Okahara Mitsuo 
Published: July 2006

Abstract
A new facile method of synthesizing crown ethers from oligoethylene glycols by treating them with arenesulfonyl or alkanesulfonyl chlorides in the presence of alkali metal hydroxide or alkoxide was described. 15-Crown-5 and 21-crown-7 were synthesized from pentaethylene glycol and heptaethylene glycol respectively in good yields, while 18-crown-6 was obtained from both hexaethylene glycol and triethylene glycol. Although the main product was 24-crown-8 in the reaction of tetraethylene glycol/TsCl/Na(K)OH in dioxane, 12-crown-4 was obtained in a moderate yield from the reaction of tetraethylene glycol/benzenesulfonyl chloride/t-BuOLi in t-BuOH. Furthermore, the analogous treatment of PEG 200 afforded a mixture of 15-, 18-, 21-, and 24-crown ethers. The reaction conditions were investigated, and the scope of the reaction was discussed.
Chiral Mesophases of 12-Hydroxyoctadecanoic Acid in Jelly and in the Solid State. I. A New Type of Lyotropic Mesophase in Jelly with Organic Solvents
Authors: Tachibana Taro , Mori Tomoko , Hori Kayako 
Published: July 2006

Abstract
Thermally reversible jellies of optically active 12-hydroxyoctadecanoic acid (12HOA) with CCl4 or aromatic solvents form a lyotropic mesophase, which shows enantiomeric circular dichroism (CD) and induced CD due to achiral molecules added to the jellies, indicating that the jellies have a supramolecular helicoidal structure. The X-ray examination revealed that the jellies are composed of a number of small, ordered domains with such a lamellar structure as is observed in the crystalline solid. The supramolecular helicoidal structure was associated with the lamellar structure; as a result, it was suggested that the lyotropic mesophase has a chiral smectic structure and, furthermore, that the mesophase is present in thin, fibrous aggregates of 12HOA molecules within which the jellies are enmeshed.
Hydroxyamidine as a Highly Selective Extractant for Spectrophotometric Determination of Molybdenum with Thiocyanate
Authors: Kharsan Raghunandan Singh , Mishra Rajendra K 
Published: July 2006

Abstract
A highly selective method for the extractive-spectrophotometric determination of molybdenum is described. Molybdenum is reduced with ascorbic acid in strongly acidic media (2.0–4.5 mol dm−3 HCl), and complexed with N1-hydroxy-N1-p-tolyl-N2-(3,4-dimethylphenyl)benzamidine in the presence of thiocyanate. The stoichiometry of mixed complex is found to be 1:2:2 (metal:reagent:thiocyanate). The red-orange molybdenum complex shows a sharp maximum at 470 nm having molar absorptivity 3800 dm3 mol−1 cm−1. All the metal ions associated with a matrix of molybdenum such as Ni(II), Co(II), Cu(II), Mn(II), Ti(IV), Zr(IV), V(V), Nb(V), Ta(V), and W(VI) do not interfere. The applicability of the method has been tested with an ore and various alloys.
The Configuration of the Adsorbed Polymer at the Solid-Liquid Interface as Depicted by ESR and IR Studie
Authors: Sakai Harutoshi , Imamura Yoshio 
Published: July 2006

Abstract
Bound segment fractions of adsorbed poly(methyl methacrylate) on silica in CCl4 were determined by both the spin-labeling technique and infrared spectroscopy. The ESR method yielded considerably larger values than the IR, indicating a highly flattened structure of the adsorbed polymer. However, the greater reliability of the ESR method was pointed out.
The Adsorption of Dodecyldimethylammonium Chloride on Aqueous Surfaces of Concentrated NaCl Solutions
Authors: Ozeki Sumio , Ikeda Shoichi 
Published: July 2006

Abstract
Surface tension of aqueous NaCl solutions of dodecyldimethylammonium chloride has been measured at high NaCl concentrations. Surface excesses of surfactant cation, Na+ and Cl− are derived by means of the Gibbs adsorption isotherm from the derivatives of surface tension with respect to surfactant concentration and NaCl concentration. The rational mean activity coefficients of surfactant and NaCl are both approximated by a common expression satisfying the Brönsted principle for mixed electrolytes but including the ionic strength as a variable. Saturated value of surface excess of surfactant cation remains constant at low NaCl concentrations up to 0.10 M, while it increases as the NaCl concentration exceeds 0.50 M. The adsorption of Na+ is negative at low NaCl concentrations, but it increases rapidly and is positive above 0.50 M NaCl. Surfactant and NaCl are subject to the strong salting-out effect when the NaCl concentration is higher than 0.50 M. The Corrin-Harkins plot of the critical micelle concentration at high NaCl concentrations deviates from the straight line.
Catalysis by Alkaline Earth Metal Oxides. I. The Mechanism of Ethylene Hydrogenation on Calcium Oxide
Authors: Kasama Kaname , Inoue Yasunobu , Yasumori Iwao 
Published: July 2006

Abstract
The mechanism of ethylene hydrogenation on a thermally activated CaO was studied in the overall temperature range of 197–623 K. The maximum in the reaction rate was observed around 320 K, while the activation energy was found to vary with the range of reaction temperatures, i.e., 12.6 kJ/mol (197–273 K) and −16.7 kJ/mol (373–623 K). The partial pressure dependence of the rate was also different in these ranges; the reaction orders with respect to the hydrogen and ethylene pressures were 0.7 and nearly zero at 273 K respectively, whereas the orders shifted to 1.0 and 0.9 at 523 K in the pressure range from 6 to 40 Torr (1 Torr=133.3 Pa). The reaction with deuterium at 523 K produced ethane containing widely distributed deuterium and was accompanied by the formation of highly-exchanged ethylene, HD, and H2 molecules in the gas phase. On the contrary, the reaction at 273 K formed ethane [D2] (&gt;60%) selectively, and the hydrogen-deuterium exchange occurred to a lesser extent in both ethylene and deuterium. By the proposed associative mechanism, the variation in the kinetic behavior with the temperature was explained in terms of the change in the slow step from the reaction between the adsorbed hydrogen and surface ethylene to the hydrogenation of the ethyl radical. The poisoning of the hydrogenation by preadsorbed CO indicated that only 0.5% of the total surface atoms contributed actively to the reaction. On the basis of these results, the structures of active sites are briefly discussed.
X-Ray Photoelectron Spectroscopic Study of Tetrathiafulvalene–Tetracyanoquinodimethane (TTF·TCNQ) and Related High Conductive Organic Complexes
Authors: Ikemoto Isao , Yamada Masamichi , Sugano Tadashi , Kuroda Haruo 
Published: July 2006

Abstract
Tetrathiafulvalene–tetracyanoquinodimethane (TTF·TCNQ) and related high conductive organic complexes were studied by X-ray photoelectron spectroscopy (XPS). The N 1s peak shape of TTF·TCNQ evaporated film was found to change by X-ray irradiation; the high-binding energy shoulder of the N 1s peak increased its intensity with X-ray irradiation time and finally showed a new peak separated by about 1.5 eV from the main peak. TTF·TCNQ was found to be 1:1 both in the surface and in the bulk. The amounts of charge transfer in TTF·TCNQ and other TTF complexes as well as those in 5,6:11,12-bis(dithio)naphthacene(tetrathiotetracene, TTT) complexes were determined from the analysis of the S 2p peak shape. The amount of charge transfer is 0.56±0.05 in TTF·TCNQ and 0.55±0.05 in TTF·TNAP (tetracyanonaphthoquinodimethane). The molecular ratio of (donor)+ in donor molecules is 0.71±0.05 in TTF·Br0.7, 0.52±0.05 in TTF·I0.7, 0.65±0.05 in (TTF)3(BF4)2, 0.49±0.05 in (TTT)2I3, and 0.93±0.05 in (TTT)(TCNQ)2, which correspond respectively to 100, 73, 100, 100, and 100% charge transfer between donors and acceptors. The N 1s peak shape of TTF·TCNQ is also discussed.
Electrochemical Study of Spectral Sensitization Using AgCl Sheet Crystal as a Window. Ag+ Ion Effect
Authors: Sumi Seiichi , Watanabe Tadashi , Fujishima Akira , Honda Kenichi 
Published: July 2006

Abstract
With use of AgCl sheet crystal as a window, sensitized photocurrent was measured in an electrochemical cell with a lock-in amplifier. With five sensitizing dyes having different lowest vacant levels, it was found that the higher the level of the dye, the larger the sensitized photocurrent, the sensitized photocurrent increasing with decreasing pAg of the dye-bearing solution. The Ag+ ion effect can be explained by a band edge shift of the AgCl electrode, which also explains the blue desensitization recovery by Ag+ ions.
Effect of the Phase Transition in Liposomes on the Fluorescence of Amphiphilic Cyanine Dyes
Authors: Onuki Kaoru , Kurihara Kazue , Toyoshima Yoshinori , Sukigara Mitsunori 
Published: July 2006

Abstract
The dependence of fluorescence intensity of amphiphilic cyanine dyes on the thermotropic fluid-solid phase transition of lipid bilayer membranes has been investigated. N,N′-dioctadecyl oxacarbocyanine iodide or N,N′-dioctadecyl thiacarbocyanine bromide was incorporated into single lamellar liposomes, and the fluorescence intensity of each dye was observed to be modified considerably by the phase transition of the lipid bilayers. An amphiphilic cyanine dye with single long alkyl chain, N-octadecyl-N′-methyl thiacarbocyanine bromide was also incorporated in the lipid bilayers, but in this case, the phase transition showed little effect on the fluorescence intensity. These results were interpreted in terms of the effect of the bilayer membrane fluidity and rigidity on the rotational motion of the incorporated cyanine dyes. The phase transition parameters were obtained by applying those amphiphilic dyes as the fluorescence probe of the phase transition of the liposomes.
Asymmetric Hydrogenation with Chiral Aminophosphine–Rhodium Complexes and Chiral Recognition by Bisphosphine–Rhodium Complexes in the Asymmetric Hydrogenation of Olefins through the Chiral Helical Conformation of Phenyl Groups on the Phosphorus Atom
Authors: Onuma Ken-ichi , Ito Tomiyasu , Nakamura Asao 
Published: July 2006

Abstract
The asymmetric hydrogenation of α-acylaminocinnamic acids with the rhodium complex of (1R,2R)-1,2-bis(N-diphenylphosphino-N-methylamino)cyclohexane has been reported to give preferentially (S)-amino acids. On the contrary, it has been found that the enantiomeric (R)-amino acids are obtained by hydrogenation with the rhodium complex of (1R,2R)-1,2-bis(diphenylphosphinamino)cyclohexane. The study of the inversion of the stereoselectivity of the rhodium complex of (1R,2R)-1,2-bis(diphenylphosphinamino)cyclohexane by the N-methylation of the ligand in asymmetric hydrogenation has been described. From stereochemical considerations, the chiral helical conformation of the phenyl groups attached on the phosphorus in bisphosphine-rhodium complexes may be responsible for the induced chirality of the product of the hydrogenation. A complex with a left-handed helicity would give (R)-amino acid, and a complex with a right-handed helicity would give (S)-amino acid. The effects of the solvents and substrate structures on the optical yields are also discussed.
Direct Conversion of Arylamines to the Corresponding Halides, Biphenyls, and Sulfides with t-Butyl Thionitrate
Authors: Oae Shigeru , Shinhama K\={o}ichi , Kim Yong Hae 
Published: July 2006

Abstract
t-Butyl thionitrate have been found to be an excellent diazotizing reagent of arylamines in aprotic nonpolar media, affording eventually such products as aryl chlorides, aryl bromides, aryl iodides, biphenyls, and aryl methyl sulfides in the presence of CCl4, CHBr3, I2, benzene, and dimethyl disulfide, respectively, via extrusion of N2.
Chemistry of N-Thiosulfinylanilines. V. Reactions of N-Thiosulfinylanilines with Nucleophilic Reagents
Authors: Inagaki Yoshio , Hosogai Takeo , Okazaki Renji , Inamoto Naoki 
Published: July 2006

Abstract
2,4-Di-t-butyl-6-methyl-N-(thiosulfinyl)aniline (1) gave 2,4-di-t-butyl-6-methylaniline in the reactions with such reagents as alkylamines, thiourea, butyllithium, alkylmagnesium halides, 1-(1-pyrrolidinyl)cyclopentene, and hydrogen sulfide. Triphenylphosphine reacted with 1 to give (2,4-di-t-butyl-6-methylphenylimino)triphenylphosphorane and bis(2,4-di-t-butyl-6-methylphenyl)sulfur diimide. Reaction of triphenylphosphine with 2,4,6-tri-t-butyl-7,8-dithia-9-azabicyclo[4.3.0]nona-2,4,9-triene afforded 2,4,6-tri-t-butylaniline, bis(2,4,6-tri-t-butylphenyl)sulfur diimide, and 2,4,6-tri-t-butyl-N-sulfinylaniline (7). The sulfur diimide was considered to be formed via intermediary 2,4,6-tri-t-butylthionitrosobenzene, which was trapped by oxygen to give the N-sulfinyl derivative 7.
Isotope Effect of the Glass Transition Temperature of Aqueous Solution. LiCl and ZnCl2 Solutions in Water and D2O
Authors: Kanno Hitoshi , Shirotani Ichimin , Minomura Shigeru 
Published: July 2006

Abstract
Glass transition temperatures of the LiCl and ZnCl2 solutions in both water and D2O were measured as a function of the concentration of the salt. The composition dependence of isotope effect is briefly discussed for these solutions.
The Fifth Overtone Spectra of Aryl C–H Stretching Vibrations in C6H5CH3−nCln
Authors: Mizugai Yoshihiro , Katayama Mikio 
Published: July 2006

Abstract
The fifth overtone frequencies of the aryl C–H vibration of C6H5CH3−nCln were observed by means of the thermal-lens technique. The shifts of their vibrational frequencies from that of benzene were found to be proportional to the inductive contribution of the Hammett σ, thus supplying information on the reactivity of the chemical bond.
Bromophenols from the Red Alga Rhodomela larix
Authors: Suzuki Minoru , Kowata Nobuhiko , Kurosawa Etsuro 
Published: July 2006

Abstract
Two new bromophenols, 3-bromo-4-hydroxybenzaldehyde and a brominated dibenzyl ether derivative, were isolated from the red alga Rhodomela larix, along with several known bromophenols which have previously been isolated from R. larix and other species.
Requirements for an “Organic Metal”
Authors: Saito Gunzi , Ferraris John P 
Published: July 2006

Abstract
Current theories on the origin of high electrical conductivity in TCNQ-based materials emphasize the need for incomplete charge transfer as well as segregated stacks of donor and acceptor molecules and uniform spacing within the stacks. The requirements for an “organic metal” are discussed in terms of partial charge transfer. An examination of 61 structurally related TTF–TCNQ, based complexes suggests that the combinations with the redox potential −0.02≤E1(D)−E1(A)≤0.34 V have a high possibility of being “organic metals.” A method to arrange the complex by the difference between the electrochemical half-wave potentials of the donor and the acceptor molecule is proposed to predict electrical properties of the complex.
Light Scattering Study of Local Structures in Solutions. Cooperative Translational Motion of Alcohol Molecules in Carbon Tetrachloride Solutions
Authors: Kato Tadashi , Ito Nobuyuki , Fujiyama Tsunetake 
Published: July 2006

Abstract
The concept of a “moving unit”—a group of molecules which move together for the time much longer than the velocity auto-correlation time, τ—was introduced in order to obtain information about cooperative translational motions of molecules in associated solution. The mutual diffusion coefficient was theoretically expressed in terms of the self diffusion coefficients and the number of moving units. The theoretical results were applied to the study of the mutual diffusion coefficients for methanol–carbon tetrachloride and ethanol–carbon tetrachloride solutions measured by Rayleigh scattering. It was shown that the mean number of alcohol molecules which constitute a moving unit is much smaller than the mean association number of alcohol, especially in the high concentration range of alcohol. This indicates that the hydrogen-bonded polymer of alcohol molecules cannot move without changing the polymer shape within the time τ.
Ion Pair Formation between Electro-generated 1,2-Naphtoquinone Anion Radicals and Alkali Metal Cations in Acetonitrile
Authors: Fujinaga Taitiro , Okazaki Satoshi , Nagaoka Tsutomu 
Published: July 2006

Abstract
Ion association of 1,2-naphthosemiquinone with the alkali metal cations in acetonitrile has been comprehensively studied by the use of ESR, absorption spectroscopy, polarography and with MO calculation. A continuous flow electrolysis system with a glassy carbon column electrode has been developed for the rapid quantitative preparation of organic free radicals, whose ESR spectrum or absorption spectrum was observed in situ. The formation constants of the ion pair with K+, Na+, and Li+ were estimated as 103.2, 104.5, and 108.0, respectively. By the addition of alkali metal cations, the half-wave potentials shifted to more positive potential in the order of K+&lt;Na+&lt;Li+. The proton hyperfine splitting constants in the ESR also varied in this order. This column electrolysis method is considered to be a powerful technique, particularly for the study of short lived free radicals, because the quantitative electrolysis is performed rapidly even in a solution of extremely diluted supporting electrolyte, such as 0.1 mM (mmol/dm3).
Stereochemistry of Λ-uns-(2S,2S′)-1,1′-Trimethylenedipyrrolidine-2,2′-dicarboxylato Cobalt(III) Complexes with N-Alkyl Substituted Amino or Cyclic Imino Acids
Authors: Okabayashi Minahiro , Okamoto Ken-ichi , Hidaka Jinsai 
Published: July 2006

Abstract
((2S,S′-1,1′-Trimethylenedipyrrolidine-2,2′-dicarboxylato)(α-amino carboxylato)cobalt(III) complexes were prepared and characterized, where the α-amino carboxylate ligand is glycinate, (R)- or (S)-alaninate, (R)- or (S)-valinate, sarcosinate, N-ethylglycinate, (R)-prolinate, or (S)-pipecolate ((S)-2-piperidinecarboxylate). Of the three possible isomers, only the Λ-uns-mer form was prepared for each of the complexes except for the glycinato complex. The (R)-prolinato and (S)-pipecolato complexes were stereoselectively prepared by using (RS)-proline or (RS)-pipecolic acid. The pipecolate ion coordinated selectively was assigned to S(C) configuration on the basis of the CD measurement of the 2,4-dinitrophenyl-pipecolic acid. The nitrogen atom of the sarcosinate, N-ethylglycinate, (R)-prolinate, or (S)-pipecolate ion, which coordinated stereoselectively to Co(III) ion, took the R(N) configuration. The stereoselectivity in this work was discussed on the basis of the electronic absorption, CD, and PMR spectra.
Chiral Recognition in Catalytic Hydrogenation of α-Acylaminoacrylic Acids by Cationic Rhodium(I) Complexes of Chiral Aminophosphines Derived from (R,R)-1,2-Cyclohexanediamine or (R)-1,2-propanediamine
Authors: Kashiwabara Kazuo , Hanaki Kazuhiro , Fujita Junnosuke 
Published: July 2006

Abstract
Four chiral diphosphines, (R,R)-1,2-bis[N-methyl(diphenylphosphino)arnino]cyclohexane, (R,R)-1,2-bis[(diphenylphosphino) amino] cyclohexane, (R)-1,2-bis[N-methyl(diphenylphosphino)amino]propane, and (R)-1,2-bis[(diphenylphosphino)amino] propane have been prepared from the corresponding optically active diamines. The cationic 1,5-cyclooctadiene rhodium(I) complexes with these diphosphines act as effective homogeneous catalysts for the stereoselective hydrogenation of α-acylaminoacrylic acids. The optical yields and the absolute configurations of the products depend on the kind of diphosphine ligands. The (R,R)-1,2-bis[N-methyl(diphenylphosphino)amino]cyclohexane complex catalyst yields N-benzoyl-(S)-leucine, N-benzoyl-(S)-phenylalanine, and N-acetyl-(S)-phenylalanine in 94, 92, and 89% e.e., respectively. The other three catalysts are less effective (6–74% e.e.). The aminophosphine complexes with methyl groups on the nitrogen atoms always give (S)-amino acids, those with no methyl group (R)-amino acids. Such a difference in the chiral recognition has been discussed on the basis of circular dichroism spectra and Dreiding molecular models of the rhodium(I) complexes.
The Use of Grignard Reagents in the Synthesis of Carbohydrates. II. The Cleavage of Acetal Protecting Groups in Sugar Derivatives
Authors: Kawana Masajiro , Emoto Sakae 
Published: July 2006

Abstract
The selective reaction of acetal protecting groups in sugars with Grignard reagents is described. The treatment of 1,2:5,6-di-O-cyclohexylidene-α-d-glucofuranose (1) with methylmagnesium iodide in benzene-ether at about 85 °C gave 1,2-O-cyclohexylidene-6-O-(1-methylcyclohexyl)-α-d-glucofuranose. When isopropylmagnesium iodide or t-butylmagnesium bromide was used instead of methylmagnesium iodide, 1 gave 1,2-O-cyclohexylidene-6-O-(cyclohex-1-enyl)-α-d-glucofuranose and the corresponding 6-O-cyclohexyl derivative. The selective cleavage of the acetal protecting groups in some other sugars with the Grignard reagents is also described.
The Solvent Extraction of Alkali Metal Picrates by 12-Crown-4
Authors: Takeda Yasuyuki 
Published: July 2006

Abstract
The overall extraction equilibrium constants (Kex) for 1: 1: 1 complexes of 12-crown-4 (12C4) with alkali metal picrates between benzene and water have been determined at 25 °C. The Kex series for the 12C4 for the alkali metal ions are given by Na+&gt;Li+&gt;K+&gt;Rb+≥Cs+.
Photo-CIDNP Observed in O-Methylbenzoin–Carbon Tetrachloride System
Authors: Maruyama Kazuhiro , Furuta Hiroyuki , Otsuki Tetsuo 
Published: July 2006

Abstract
Photo-induced decomposition of O-methylbenzoin in carbon tetrachloride was investigated. A reaction scheme is proposed with the aid of photo-CIDNP technique and product analysis.