bluuebunny/crossref_metadata_2025_split huggingface dataset:
Irreversibility of Single Electron Transfer Occurring from Trivalent Phosphorus Compounds to Iron(III) Complexes in the Presence of Ethanol
Authors: Yasui Shinro , Itoh Kenji , Tsujimoto Munekazu , Ohno Atsuyoshi 
Published: September 2002

Abstract
Various types of trivalent phosphorus compounds (1; Ph(3-n)P(OR)n) underwent single electron transfer (SET) to unsubstituted (2H) and 5-chloro-substituted tris(1, 10-phenanthroline)iron(III) complexes (2Cl) in the presence of ethanol in acetonitrile, resulting in the reduction of 2 to the corresponding iron(II) complexes. The rate constants (kp) for the overall SET process were determined spectrophotometrically to show that within each series of 1 with an identical alkoxy group OR, log kp correlates linearly with the difference in the half-wave potentials (ΔE1/2) between 1 and 2. The slope of each correlation line gave an α-value for each series of 1. The α-values were significantly smaller than unity, indicating that the SET step is irreversible, even though this step is endothermic. The trivalent phosphorus radical cation 1•+ generated in the SET step undergoes a rapid ionic reaction with ethanol, which is certainly the origin of the irreversibility. Upon examining the α-values more closely, it was found that the transition state of the SET step becomes earlier with increasing bulkiness of the substituent OR. It is concluded that 1 and 2 form a tight encounter complex to undergo SET from the former to the latter.
Selective 3-O- and/or 6-O-Glycosidation of Unprotected O- and S-Glycosides Promoted by an Intramolecularly Coordinated Arylboronic Compound
Authors: Oshima Kenji , Yamauchi Takeshi , Shimomura Masato , Miyauchi Shinnosuke , Aoyama Yasuhiro 
Published: September 2002

Abstract
Arylboronic compound 1 that has intramolecular coordination promotes highly regioselective 3-O- and/or 6-O-glucosidation and -galactosidation of methyl fucopyanoside, methyl galactopyranoside, methyl mannopyranoside, p-methylphenyl 1-thiogalactopyranoside, and p-methylphenyl 1-thiomannopyranoside with peracetylated glucopyranosyl bromide or galactopyranosyl bromide as a glycosyl donor in the presence of Ag2CO3, Et4NI, and molecular sieves 4A in THF. Glycosyl acceptors and promoter 1 form cyclic boronates at cis-vicinal diol (3,4-diol or 2,3-diol) and/or 4,6-diol moieties with concomitant activation of the less hindered 3-O (equatorial) and/or 6-O (primary) nucleophiles via intramolecular O → B coordination. This reaction provides a novel method of simultaneous one-pot 3,6-O-double glycosidation (glucosidation and galactosidation) to give trisaccharides. However, attempted mannosidation with peracetylated mannopyranosyl bromide only gives rise to orthoesters.
9-Phenylxanthen-9-ylium and 9-Phenylthioxanthen-9-ylium Ions: Comparison of o- and p-Substitutions in the 9-Phenyl Group by Cyclic Voltammetry and Visible Spectra
Authors: Erabi Tatsuo , Asahara Masahiro , Miyamoto Masahumi , Goto Keisuke , Wada Masanori 
Published: September 2002

Abstract
9-Arylxanthen-9-ylium (3a–i) and 9-arylthioxanthen-9-ylium (4a,b,e–i) perchlorates [aryl = 2,4,6-(MeO)3C6H2 (a), 2,6-(MeO)2C6H3 (b), 2-MeOC6H4 (c), 4-MeOC6H4 (d), 3-Br-2,6-(MeO)2C6H2 (e), 2,4,6-Me3C6H2 (f), 2-MeC6H4 (g), 4-MeC6H4 (h), C6H5 (i)] were prepared by the reactions of 9-arylxanthen-9-ols or 9-arylthioxanthen-9-ols with perchloric acid. Their LUMO and HOMO levels were estimated from the redox potential (E0) in cyclic voltammetry and λmax in the UV–visible spectra measured for a 1,2-dichloroethane solution, and were compared with those of 9-aryl-1,8-dimethoxyxanthen-9-ylium ions (8b,i). We found that 1) both the LUMO and HOMO levels varied almost in the same order of substituent on the 9-phenyl group; 2) the MeO-group on the 9-phenyl group was more effective to raise both the HOMO and LUMO levels than the Me-group; 3) the HOMO levels of 3 and 4 were more sensitive than the LUMO levels to the change in the 9-aryl group; 4) p-substitution by MeO- or Me-groups was more effective to raise the HOMO and LUMO levels than o-substitution; 5) the presence of two o-MeO groups was more effective to raise the HOMO and LUMO levels than one o-MeO group; 6) a m-bromination of 9-aryl group in 3b or 4b greatly lowered both LUMO and HOMO levels, as observed for 3e or 4e; 7) both the HOMO and LUMO levels of 8b and 8i were higher than those of 3b and 3i, respectively; 8) the LUMO level of 3b was higher than that of 8i, the isomer.
Palladium-Catalyzed Direct Conversion of Carboxylic Acids into Ketones with Organoboronic Acids Promoted by Anhydride Activators
Authors: Kakino Ryuki , Narahashi Hirohisa , Shimizu Isao , Yamamoto Akio 
Published: September 2002

Abstract
Various carboxylic acids are catalytically converted into ketones on treatment with organoboron compounds in the presence of activators and palladium catalysts. Detailed examination of factors influencing the yield of ketone formation revealed the following characteristics of the reactions: (a) Palladium complexes containing tertiary phosphine ligands, particularly triphenylphosphine and tricyclohexylphosphine, are most effective among the palladium complexes; (b) Dioxane and THF are suitable as the solvent; (c) Dimethyl dicarbonate is required as the activator to obtain ketones in high yields. The process provides a general, versatile, synthetic method to produce various symmetrical and unsymmetrical ketones with aromatic, aliphatic, and heterocyclic groups. The mechanism proposed for the catalytic process involves (i) exchange reaction of the carboxylic acid employed with dimethyl dicarbonate added as the activator to form a mixed anhydride of the carboxylic acid and mono methyl ester of carbonic acid; (ii) oxidative addition of the mixed anhydride to zerovalent palladium species to give an (acyl)(methyl carbonato)palladium species; (iii) decarboxylation of the methyl carbonato ligand to give (acyl)(methoxo)palladium species; (iv) transmetallation of the (acyl)(methoxo)palladium species with an arylboronic acid to give an (acyl)(aryl)palladium species; and (v) reductive elimination of the (acyl)(aryl)palladium species to liberate the coupling product of the acyl and aryl ligands with regeneration of the Pd(0) species. Not only homogeneous catalyst systems but also heterogeneous systems were found to give ketones under mild conditions. On the basis of the present study involving the acyl(methoxo)palladium complexes generated in the reaction mixture of carboxylic acids with dimethyl dicarbonate on reaction with Pd(0) complexes, we also developed a new catalytic process to convert carboxylic acids with terminal alkynes into α, β-alkynyl ketones under similar conditions.
Synthesis and Characterization of a Poly(amide amine) Dendrimer Disulfide Having Hydroxy Groups as the Terminals
Authors: Takaguchi Yutaka , Saito Keiko , Suzuki Shinji , Hamada Kunihiro , Ohta Kazuchika , Motoyoshiya Jiro , Aoyama Hiromu 
Published: September 2002

Abstract
A Poly(amide amine) dendrimer with a diphenyl disulfide at the core was synthesized and well characterized, and then used for a host molecule for an organic dye. The molecule shows a reversible redox behavior between the dendron and the dendrimer, being achieved under chemical reactions. Furthermore, a marked difference of encapsulating fashion was observed as the structure changed from dendrimer to dendron.
Synthesis, Structure, and Mesomorphic Properties of Liquid Crystals with a Bitropone Core
Authors: Kubo Kanji , Sutoh Takanori , Mori Akira , Ujiie Seiji 
Published: September 2002

Abstract
New troponoid liquid crystals (1–4) with a bitropone core were prepared. The ester derivatives (1) had enantiotropic smectic A and/or C phases with higher thermal stabilities than the corresponding benzenoid derivatives (5), which had a smectic B phase. The amide derivatives (3) had an enantiotropic smectic A phase, but the ether (2) and alkylamine (4) derivatives were not mesomorphic. The crystals of 1c had a layer structure with an intermolecular π–π interaction between the bitropone cores. X-ray diffraction studies revealed that the layer spacings of the smectic A and C phases of 1i were not very much different.
Reactions of t-Butylphosphine–Borane with Various Electrophiles and Synthesis of Optically Active t-Butylmethylphosphine–Borane
Authors: Oohara Nobuhiko , Imamoto Tsuneo 
Published: September 2002

Abstract
The reactivity of t-butylphosphine–borane toward various electrophiles was studied with a focus on alkylation. Monoalkylation of this compound proceeded smoothly in good yields (61–85%). Disubstituted derivatives were also synthesized in good yields (86–99%). Optically active t-butylmethylphosphine–borane was prepared from t-butylphosphine–borane by resolution of intermediate diastereomers of (1S)-endo-2-bornyloxycarbonyl(t-butyl)methylphosphine-borane.
Magnesium Amide-Induced Pummerer-Type Reactions of Cyclopropyl Sulfoxides. Synthesis of Cyclopropanone Dithioacetals
Authors: Kobayashi Kazuhiro , Horita Masatoshi , Irisawa Susumu , Matsunaga Akihiro , Morikawa Osamu , Konishi Hisatoshi 
Published: September 2002

Abstract
The reaction of cyclopropyl phenyl sulfoxide with a magnesium amide, generated from ethylmagnesium bromide and diisopropylamine, gave 1-(phenylthio)cyclopropanol in 72% yield. When the diisopropylmagnesium reagent was treated with a thiol prior to an interaction with cyclopropyl phenyl sulfoxides, symmetrical and unsymmetrical cyclopropanone dithioacetals were produced in fair yields along with small quantities of the corresponding 1-(phenylthio)cyclopropanols.
Synthesis of Unsymmetrical Ketones by Palladium-Catalyzed Cross-Coupling Reaction of Carboxylic Anhydrides with Organoboron Compounds
Authors: Kakino Ryuki , Yasumi Sayaka , Shimizu Isao , Yamamoto Akio 
Published: September 2002

Abstract
On the basis of fundamental studies on oxidative addition of carboxylic anhydrides to zerovalent palladium complexes to yield acyl(carboxylato)bis(tertiary phosphine)palladium(II) complexes and their reactions with organoboronic acids to yield ketones, a novel catalytic process has been developed. This converts carboxylic anhydrides and organoboron compounds into ketones catalyzed by palladium complexes under mild conditions. The process provides a general, versatile, synthetic method to produce various symmetrical and unsymmetrical ketones with aromatic, aliphatic, and heterocyclic groups. The catalytic cycle is proposed to comprise (a) oxidative addition of a carboxylic anhydride to produce an acyl(carboxylato)palladium intermediate, (b) transmetallation with an organoboron compound to give an acyl(organo)palladium intermediate, and (c) its reductive elimination to yield a ketone. Not only homogeneous catalyst systems but also heterogeneous systems were found to give ketones under mild conditions.
Non-Linearity and Non-Additivity of Substituent Effects in Solvolysis of 1,1-Diphenylethyl p-Nitrobenzoates
Authors: Uddin Md Khabir , Fujio Mizue , Kim Hyun-Joong , Rappoport Zvi , Tsuno Yuho 
Published: September 2002

Abstract
The solvolysis rates of 1,1-diarylethyl p-nitrobenzoates and chlorides Y-Ar(X-Ar)CMe-LG (LG = OPNB, Cl) have been determined conductimetrically at 25 °C in 80% (v/v) aqueous acetone. A linear Yukawa–Tsuno (Y–T) correlation was found for the symmetrical subseries (X = Y), showing a precise additivity relationship for the whole substituent range with ρsym = -3.78 and rsym = 0.77. The unsymmetrical subsets (X ≠ Y) gave statistically less reliable Y–T correlations, the apparent ρ value decreasing significantly when the fixed substituent Y becomes more electron-donating, which is in line with expectations from the Reactivity-Selectivity Relationship. In the whole dispersion pattern, both strong p-π-donor and electron-withdrawing substituents in any fixed-Y subsets exhibit significant rate-enhancement deviations from the points of X = Y on the reference ρsym line, which suggests an anti-Hammond shift of the transition state. However, there was a precise Extended Brønsted Linear Relationship between the pKR+ values for the hydration of 1,1-diarylethylenes and the rates of solvolysis of the p-nitrobenzoates with a slope of unity (α = 1.03). This is direct, convincing evidence that there is no significant shift of the transition-state coordinate over the whole range of substituent change.
Microwave-Assisted Cross-Coupling Reaction of Sodium Tetraphenylborate with Aroyl Chlorides on Palladium-Doped KF/Al2O3
Authors: Wang Jin-Xian , Yang Yihua , Wei Bangguo , Hu Yulai , Fu Ying 
Published: September 2002

Abstract
A palladium-catalysed cross-coupling reaction of sodium tetraphenylborate with aroyl chloride using KF/Al2O3 as supported reagents in the presence of acetone under microwave-irradiation conditions gives unsymmetrical ketones in good high yield.
Behavior of Hydrogen Peroxide in the Atmosphere and Rainwater in Kyoto, and Its Effect on the Oxidation of SO2 in Rainwater
Authors: Yamada Etsu , Tomozawa Kenichi , Nakanishi Yuuki , Fuse Yasuro 
Published: September 2002

Abstract
The diurnal and seasonal variations of hydrogen peroxide (H2O2) concentrations in the atmosphere and rainwater were measured in Kyoto since 1998, and the factors affecting the formation of atmospheric H2O2 were analyzed. The concentration of atmospheric H2O2 was larger in the daytime than at night, the difference being small in the winter and large during the spring and summer. The seasonal variation of atmospheric H2O2 in Kyoto, 0.09–5.8 ppbv, showed a summer maximum and a winter minimum. The concentration of atmospheric H2O2 correlated the most with the solar radiation, UV radiation and temperature, while it was inversely correlated with the relative humidity. Atmospheric H2O2 increased rapidly above ca. 20 °C. The formation of atmospheric H2O2 may be mainly due to a photochemical reaction. The H2O2 concentration in rainwater had a high level of 1.2–65.1 µM (1 M = 1 mol dm-3) in the summer, while maintaining a low level of less than 0.01 µM in the winter. Gaseous H2O2 may be rapidly removed from the atmosphere by wet deposition and aqueous H2O2 in rain may originate mostly from gas-phase H2O2. The wet deposition of H2O2 in Kyoto was estimated to be 11.7 mmol m-2 y-1 in 1999 and 9.11 mmol m-2 y-1 in 2000. H2O2 may be a dominant oxidant for SO2 in the summer.
Methanol Synthesis from CO and CO2 Hydrogenations over Supported Palladium Catalysts
Authors: Fujitani Tadahiro , Nakamura Isao 
Published: September 2002

Abstract
The hydrogenation of CO and CO2 was carried out over palladium catalysts supported on various metal oxides. A significant support effect of Ga2O3 on the methanol synthesis activity from CO2 hydrogenation was observed. On the other hand, a Pd/ZrO2 catalyst showed high methanol synthesis activity from CO hydrogenation. Furthermore, the hydrogenation reaction over Pd/Ga2O3 and Pd/ZrO2 catalysts was investigated by in situ infrared spectroscopy in order to understand the active sites and the reaction mechanism. On the Pd/Ga2O3 catalyst, surface formate and methoxy species were observed during CO and CO2 hydrogenation. In contrast, the reaction pathway was clearly different between CO and CO2 hydrogenation over the Pd/ZrO2 catalyst. That is, surface formaldehyde and methoxy species were observed as intermediates during CO hydrogenation, while surface formate and methoxy species were detected during CO2 hydrogenation. It was thus found that the reaction mechanisms of methanol synthesis from CO and CO2 hydrogenation were strongly dependent on the types of supports over the Pd catalysts.
Recycling of Cyanide Wastewater Applying Combined UV–Ozone Oxidation with a Titanium Dioxide Catalyst and Ion Exchange Resin Method
Authors: Wada Hiromutsu , Murayama Takashi , Kuroda Yasuhiro 
Published: September 2002

Abstract
We investigated how to reuse water from cyanide wastewater by combining UV–ozone oxidation with a titanium dioxide (TiO2) catalyst and de-ionization by applying an ion exchange resin method. A TiO2 catalytic film was formed on the surface of quartz tubes by a novel sol-gel method. During UV–ozone oxidation with the TiO2 catalyst, cyanide ion (CN-) was oxidized to cyanate ion (OCN-) in a relatively short time without the application of any other chemicals. The processed water was smoothly de-ionized by an ion exchange resin method. The cyanate ion was decomposed into NH4+ and CO2 by hydrolysis under acidic conditions in a cation exchange resin column. Ammonium ion (NH4+) adsorbed to the cation exchange resin. The electric conductivity of the effluent from the ion exchange resin column was less than 1×10-1 mS m-1. This de-ionized water could be reused as rinsing water in the plating process. These experimental results suggested that toxic cyanide wastewater could be reused as de-ionized water.
Recent Development of Linearly Ordered Multinuclear Transition-Metal Complexes
Authors: Tanase Tomoaki 
Published: September 2002

Abstract
This paper reviews the recent development of linearly ordered multinuclear transition-metal complexes, which have been of increasing interest as potential nanostructured molecular units and their precursors. In particular, it focuses on our recent results of platinum-based homo- and heteromultimetallic complexes supported by the tridentate phosphine ligands, bis(diphenylphosphinomethyl)phenylphosphine (dpmp). The synthetic strategy involved the metal core expansion using the diplatinum precursors having two uncoordinated phosphine pendants, syn- and anti-[Pt2(μ-dpmp)2(RNC)2]2+ (11 and 12), which allowed us to gain access to versatile homo- and heterotrinuclear complexes with Pt2M cores. Reactions of 11 with d10 and d8 metal fragments afforded the Pt–Pt–M metal frameworks (M = Pt, Pd, Au, Ag, Cu, Ir, Rh), and in contrast, those of 12 gave the Pt–M–Pt ones (M = Pt, Pd, Rh). The inserted position of the additional metal interestingly depends on the two dpmp arrangement of the starting diplatinum complexes. The corresponding chemistry of palladium and gold complexes is also described. Since the metal–metal bonded triplatinum complex, linear-[Pt3(μ-dpmp)2(RNC)2](PF6)2 (16), was regarded as a minimal model for the surface of metal catalysts, its reactions with various small organic molecules were examined. Further, the axial ligand exchange reactions of 16 with bulky aromatic bisisocyanide led to a one-dimensional assemblage of the linear Pt3 units, resulting in rigid rod-like cluster polymers, and the reduction of 16 afforded the linearly ordered hexaplatinum cluster molecules supported by four dpmp ligands through a direct combination of the two linear Pt3 fragments.
Probing Chemical Processes in Living Cells: Applications for Assay and Screening of Chemicals that Disrupt Cellular Signaling Pathways
Authors: Umezawa Yoshio , Ozawa Takeaki , Sato Moritoshi 
Published: September 2002

Abstract
Methods of analysis for bioactive substances that are based on cellular signaling pathways are discussed and compared with the binding assay and bioassay. For nondestructive analysis of chemical processes in living cells, we have developed some general methods and new intracellular fluorescent probes for detecting 1) second messengers, cGMP, diacylglycerol and phosphatidylinositol-3,4,5-triphosphate, 2) protein phosphorylation, 3) protein conformational changes, and 4) protein-protein interactions in live cells under a confocal laser microscope. The approaches for the present probe developments are use of fluorescence resonance energy transfer for reporting binding of substrates (analytes) to molecular recognition domains in dual-fluorophore conjugated probe molecules, and use of protein splicing chemistry for detecting protein-protein interactions. Key molecules and steps of cellular signaling pathways were visualized in relevant live cells using developed fluorescent probe molecules. These probes were found of general importance not only for fundamental biology studies, but also for assay and screening methods for chemicals that inhibit or facilitate cellular signaling pathways. Changes in cellular signals were thereby observed in nongenomic pathways of steroid hormones upon treatment of the target cells with steroid hormones and xenoestrogens. This method of analysis appears to be a rational approach to high-throughput prescreening of biohazardous chemicals such as endocrine disrupting chemicals that disrupt these cellular signaling pathways.
Transition Metal-Catalyzed Carbostannylation of Alkynes and Dienes
Authors: Shirakawa Eiji , Hiyama Tamejiro 
Published: September 2002

Abstract
Carbon–tin bonds in alkynyl-, allyl-, acyl-, alkenyl-, and arylstannanes were found to add to carbon–carbon unsaturated bonds of alkynes, 1,3-dienes and 1,2-dienes in the presence of a catalytic amount of palladium or nickel complexes to give alkenyl- or allylstannanes having various functional groups. Mechanisms are proposed that start with oxidative addition of a carbon–tin bond, or palladacycle formation followed by β-tin elimination or by the reaction with an organostannane.
Synthesis of Pyrrole Derivatives by Palladium-Catalyzed Cyclization of γ,δ-Unsaturated Ketone O-Pentafluorobenzoyloximes
Authors: Tsutsui Hironori , Kitamura Mitsuru , Narasaka Koichi 
Published: September 2002

Abstract
Various pyrrole derivatives are synthesized from γ,δ-unsaturated ketone O-pentafluorobenzoyloximes by treatment with catalytic amounts of Pd(PPh3)4 and triethylamine via alkylideneaminopalladium(II) intermediates generated by oxidative addition of the oximes to the Pd(0) complex.
Proton-Transfer Reaction in Aqueous Propylamine Solution with Poly(vinyl alcohols) by Ultrasonic Absorption Method
Authors: Nishikawa Sadakatsu , Ishikawa Kazuhiko 
Published: September 2002

Abstract
Ultrasonic absorption coefficients were measured in aqueous solutions of propylamine at 25 °C in both the absence and presence of 2.01 g dm-3 (poly(vinyl alcohols) (PVA’s)) with the number average degree of polymerization of 500, 900, 1500, and 2000. No excess absorption was observed in solutions without propylamine. A single relaxational absorption was observed in the concentration range from 0.0241 to 0.201 mol dm-3 of propylamine in both the presence and absence of PVA’s. The relaxational absorption was attributed to a perturbation of the equilibrium associated with a proton-transfer reaction from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. The rate and equilibrium constants and the standard volume change of the reaction were determined in individual solutions with PVA’s. As a result, it was found that the diffusion-controlled reaction rate constant remains constant, or increases slightly, even though the solution viscosity increases. The effect of the polymers on the reaction was interpreted in terms of an interaction between the PVA’s and the reaction intermediate and a solvent structural change.