bluuebunny/crossref_metadata_2025 huggingface dataset:
Volumetric Properties of Surfactant in Water and in Mixed Solvent from Sound Velocity and Density Measurements
Authors: Nishikawa Sadakatsu , Huang Hua
Published: September 2002

A simple, automatic and economic apparatus was constructed for a precise measurement of sound velocity using a resonance method. It gives the sound velocity value with an accuracy of less than 3×10-3% (±2 cm s-1). Sound velocity and density measurements were carried out in aqueous solutions of several compounds of alkyltrimethylammonium bromide (C1TAB, C8TAB, C10TAB, C12TAB, C14TAB, and C16TAB, where Ci is the number of carbons in straight-chain hydrocarbon groups) at 25 °C. Also, the measurements for C12TAB in a mixed solvent with water and 2-propanol were performed. The critical micelle concentrations (CMC) were determined from the inflection point of the compressibility and electric conductivity. The partial molar adiabatic compressibility (κm* ) and the partial molar volume (Vm*) for the surfactant were determined below and above CMC in water and in the mixed solvent from the apparent molar quantities. The partial molar quantities were also found to be dependent on the concentrations of the added alcohol. These results were interpreted from the points of view of the surfactant conditions and solvent structures.
Asymmetric Photolysis of 2-Phenylcycloalkanones with Circularly Polarized Light: A Kinetic Model for Magnetic Field Effects
Authors: Kohtani Shigeru , Sugiyama Masahide , Fujiwara Yoshihisa , Tanimoto Yoshifumi , Nakagaki Ryoichi
Published: September 2002

Magnetic field effects (MFE) on asymmetric photolysis involving a biradical intermediate have been investigated on a kinetic model where an intersystem crossing (ISC) of the intermediate is taken into account. Changes in the enantiomeric excesses (ee) of chiral substances with circularly polarized light (CPL) irradiation have been simulated, and the necessary conditions for observing the MFE were obtained. The asymmetric photolysis of racemic 2-phenylcycloalkanones (2-PCAs) with CPL has been carried out in both the presence and absence of a magnetic field. Since the anisotropy g factors of 2-PCAs are considerably large, the CPL-induced ee are achieved to a few percent after 90% decomposition though the MFE are not observed. The photolysis mechanism of 2-PCAs in an air-saturated solution has been also clarified. Triplet acyl–benzyl biradicals, formed via photochemical α-cleavage of 2-PCAs, react with O2 dissolved in the solution and result in the formation of acetophenone and alkenoic acids. The bimolecular reactions are diffusion-controlled and the rates are comparable to those of ISC to the singlet biradicals for all 2-PCAs. The recombination yields of the biradicals are sufficiently large. However, the biradical ISC rate shows little magnetic field dependence, which explains the absence of the MFE in this asymmetric photolysis.
Ultrasonic Effects on Electroorganic Processes. Part 22. Cathodic Crossed Hydrocoupling of Acetone with Acrylonitrile
Authors: Atobe Mahito , Fujiwara Sou , Nonaka Tsutomu
Published: September 2002

The ultrasonic effects on the cathodic-crossed hydrocoupling of acetone with acrylonitrile were examined. The total current efficiency of all products in the cathodic reduction of a mixture of acetone and acrylonitrile was little influenced by ultrasonic irradiation, while the product selectivity for crossed hydrocoupling products formed in the cathodic reduction was significantly increased by irradiation. This ultrasonic effect could be rationalized as being due to mass-transport promotion of acrylonitrile molecules as an electrophile to the cathode surface from the bulk of the electrolytic solution by the ultrasonic irradiation. Thus, the ultrasonic effect can be purposively applied to control the product selectivity in the crossed coupling reaction.
Structural Change by Chemical Substitution. Crystal Structures of Acid Salts of p-Nitrobenzoic Acid and Cyclic Secondary Amines
Authors: Moritani Yoshimitsu , Kashino Setsuo
Published: September 2002

The crystal structures of pyrrolidinium hydrogen bis(p-nitrobenzoate) (I), piperidinium hydrogen bis(p-nitrobenzoate) (II), and perhydroazepinium hydrogen bis(p-nitrobenzoate) (III) have been determined by an X-ray diffraction method in order to study an effect of the ring size of the cyclic secondary amines on the crystal structures. There is a close similarity among the crystal structures of I – III, because the schemes of the O–H···O and N–H···O hydrogen bonds are similar in these crystals. It has been found that the space group P21/c of I descends to its subgroup P1- with an occurrence of two formula units in II and ascends to its supergroup C2/c with an occurrence of disorder in III. Such a supergroup-subgroup relationship would make it possible to assume the structure after a transformation caused by chemical substitution.
Estimation of Transition Temperature of Pharmaceutical Polymorphs by Measuring Heat of Solution and Solubility
Authors: Urakami Koji , Shono Yasushi , Higashi Atsuya , Umemoto Kazuichi , Godo Masayuki
Published: September 2002

The transition temperature for enantiotropic polymorphs of pharmaceutical drugs was estimated by measuring the heat of solution and solubility at 25 °C. Instead of the conventional estimation method using van’t Hoff plots, a thermodynamic formula was derived with the heat of solution and solubility as variables for calculating the temperature at which the Gibbs free energy difference between two polymorphs in enantiotropic system become zero. The transition temperatures of polymorphic pairs for five model compounds (seratrodast, mefenamic acid, sulfathiazole, acetazolamide, and carbamazepine) calculated by the formula were in good agreement with previous studies. Since this formula requires solubility data at only one arbitrary temperature other than the heat of solution data for both polymorphs in a polymorphic pair, the proposed method is much faster than the conventional method, requiring solubility data at five or more different temperatures for preparing van’t Hoff plots.
Photoinduced Electron Transfer from Aromatic Aldehyde Hydrazones to Triplet States of C60 and C70; Electron-Mediating and Hole-Shifting Systems
Authors: Ito Osamu , Sasaki Yoshiko , El-Khouly Mohamed E , Araki Yasuyuki , Fujitsuka Mamoru , Hirao Akiko , Nishizawa Hideyuki
Published: September 2002

Photoinduced electron transfer of fullerenes such as C60 and C70 in the presence of aromatic aldehyde hydrazones (AAH’s) has been studied by the nanosecond laser photolysis which measures the transient absorption spectra in the visible and near-IR regions. Electron-transfer takes place from AAH’s to the triplet states of fullerenes; the rates and efficiencies of electron transfer are strongly affected by the electron-donor ability of AAH’s as evaluated by their oxidation potentials. The absorption bands of the radical cations of AAH’s appeared in the near-IR reagion, indicating that the radical-cation center (hole) delocalizes in the entire region of each AAH. On addition of a viologen dication to C60/C70–AAH, the electron of the anion radical of fullerenes moves to viologen dication yielding the viologen radical cation. In the systems of octaethyl porphyrinatozinc (ZnOEP)–C60/C70–AAH, the hole shift was observed from the radical cation of ZnOEP, which was produced by photoinduced electron transfer from the triplet state of ZnOEP to C60/C70, to AAH.
Selective Synthesis, Characterization, and Configurational Flexibility of the Coordinatively Unsaturated Metal Center of Half-Sandwich Type Complexes with the Less-Hindered Hydrotris(3, 5-dimethyl-4-X-1-pyrazolyl)borate Ligands [TpMe2,XMII(κ2-O,O′-L)] (M = Ni, Co; L = NO3, OAc; X = Me, H, Br)
Authors: Hikichi Shiro , Sasakura Yasuyuki , Yoshizawa Michito , Ohzu Yoshiko , Moro-oka Yoshihiko , Akita Munetaka
Published: September 2002

The selective synthesis of half-sandwich type complexes of Ni(II) and Co(II) with the less-hindered hydrotris(3,5-dimethyl-4-X-1-pyrazolyl)borate [X = Me (TpMe3; a series), H (TpMe2; b series), and Br (TpMe2,Br; c series)] ligands, [TpMe2,XMII(κ2-O,O′-L)] [L = NO3 (2), OAc (3)], has been achieved by dropwise addition of a THF solution of NaTpMe2,X to an excess amount of ML2 dissolved in MeOH. The solid state structures of the nitrato complexes 2 have been characterized by X-ray crystallography as their solvated form, 2·solv. (solv. = MeCN, MeOH), in which the metal centers have the six-coordinated octahedral geometry. Solvates are readily dissociated from the metal center upon dissolution in non-coordinationg solvents, such as CH2Cl2 and toluene, as well as drying of a solid sample to give the non-solvated five-coordinated species 2. The crystal structure of the non-solvated TpMe2Ni derivative 3bNi consists of a highly distorted trigonal bipyramidal nickel center.
Crystal- and Solution-Structure Characteristics of Ethylenediaminetetraacetatoaluminate(III) and Gallate(III)
Authors: Jung Woo-Sik , Chung Young Keun , Shin Dong Mok , Kim Sun-Deuk
Published: September 2002

The structures of complex anions, [Al(edta)]- and [Ga(edta)]- (H4edta = ethylenediaminetetraacetic acid), were investigated both in the solid state (X-ray crystallography) and in solution (1H and 13C NMR). Two complexes, (NH4)[Al(edta)]·2H2O (1) and (NH4)[Ga(edta)]·2H2O (2), are isostructural in the solid state. In both metal complexes, the central metal atoms are coordinated by six donor atoms (N2O4) in distorted octahedral coordination geometries in which two nitrogen atoms and two oxygen atoms of two acetate groups occupy the equatorial positions, and the axial positions are occupied by two oxygen atoms of two acetate groups. The 1H and 13C NMR spectra of 1 and 2 showed that acetate groups undergo rapid interchanges between the axial and equatorial positions in solution, its rate in D2O being much faster than that in dimethyl sulfoxide(dmso)-d6 for each complex, and its rate for 1 being slower than that for 2. Based on the NMR spectra, the structures of complex anions [Al(edta)]- and [Ga(edta)]- in solution are concluded to be the same as those in the solid state.
Electrochemical and In Situ SNIFTIR Spectroscopic Studies of Palladium(II) and Zinc(II) Schiff Base Complexes: Structural Control of the Electronic Communication between Two Identical Redox Sites
Authors: Wang Xiayan , Deng Zhaoxiang , Jin Baokang , Tian Yupeng , Lin Xiangqin
Published: September 2002

The mechanisms of the electron transfer of S-benzyl-N-(ferrocenyl-1-methyl-methylidene)-dithiocarbazate palladium(II)/zinc(II) complexes [Pd(lsb)2]/[Zn(lsb)2] were studied by cyclic voltammetry, differential pulse voltammetry, digital simulation and in-situ subtractively normalized interfacial Fourier transform infrared (SNIFTIR) spectroelectrochemistry. The results indicate that [Pd(lsb)2], which has a square-planar configuration, involved two consecutive one-electron steps in the redox process, while the tetrahedral configuration of Zn(II) involved a two-electron step. The [Pd(lsb)2] complex exhibits a moderately strong electronic communication between the two-ferrocene moieties, which occurs through the skeleton chain of the ligand due to extensive electron delocalization of the whole molecule during the redox process, while the [Zn(lsb)2] complex shows low electron delocalization, and has two almost identical ferrocene moieties.
Reaction of Magnesium Pinacolone Enolate with Benzaldehyde: Polar or ET Mechanism?
Authors: Yamataka Hiroshi , Shimizu Makoto , Mishima Masaaki
Published: September 2002

The carbonyl-carbon kinetic isotope effect (KIE) and the substituent effect were measured for the reaction of magnesium pinacolone enolate (CH2=C(OMgBr)C(CH3)3, 1) with benzaldehyde. The results were compared with those for lithium enolate (CH2=C(OLi)C(CH3)3, 2). A normal carbonyl-carbon KIE, a medium-sized Hammett ρ value and the results of chemical probe experiments indicated that the reaction of 1 proceeds via the polar mechanism as in the reaction of 2.
Size-Dependent Population of Trivalent Rare Earth Cations (RE3+) in [(RE)2(H2O)2(SbW9O33)(W5O18)2]15-, and Structural Characterization of a Luthetium–Polyoxotungstate Complex [Lu3(H2O)4(SbW9O33)2(W5O18)2]21-
Authors: Naruke Haruo , Yamase Toshihiro
Published: September 2002

The effect of ionic radius of trivalent rare earth cations (RE3+) on the population at two square-antiprismatic sites (Site  I and Site II) in [(RE)2(H2O)2(SbW9O33)(W5O18)2]15- was studied by luminescence spectroscopic and X-ray crystallographic measurements in the Eu/Y- and Eu/Lu-mixed systems. The results indicated that a small RE3+ cation favorably occupies Site II where RE3+ is coordinated by four bridging O atoms of [SbW9O33]9- and four terminal O atoms of [W5O18]6-. With the help of a structural characterization of pure [(RE)2(H2O)2(SbW9O33)(W5O18)2]15- (RE = Er, Y, Dy, Eu, Sm), the large occupancy of small RE3+ at Site II was explained by a favorable coordination of [SbW9O33]9- for small RE3+. A trial of the isostructural Lu complex unexpectedly showed formation of a novel [Lu3(H2O)4-(SbW9O33)2(W5O18)2]21- complex which consists of two [Lu(SbW9O33)(W5O18)]12- groups linked by [Lu(H2O)4]3+ with C2 configuration.
Self-Organized Metallo-Helicates and -Ladder with 2,2′-Biphenyldicarboxylate (C14H8O4)2-: Synthesis, Crystal Structures, and Magnetic Properties
Authors: Kumagai Hitoshi , Inoue Katsuya , Kurmoo Mohamedally
Published: September 2002

We report on the hydrothermal synthesis, single-crystal structures and magnetic properties of three one-dimensional coordination polymers employing the 2,2′-biphenyldicarboxylate dianion, (C14H8O4)2-, as the bridging component. [MII(H2O)4(C14H8O4)], where M = Co (1) and Ni (2), consist of helical chains of square-planar MII(H2O)4 bridged by C14H8O4 with each carboxylate group acting as a mono-dentate ligand. The magnetic properties are those of paramagnets (1: C = 3.34(1) cm3 K/mol, μeff = 5.17 μB, θ = -51(1) K; 2: C = 0.985(9) cm3 K/mol, μeff = 2.81 μB, θ = +27(2) K) with an antiferromagnetic exchange for 1 and a ferromagnetic exchange for 2. Cu2(C14H8O4)(H2O)2 (3) is composed of tetracarboxylato-dimeric units bridged into ladders by biphenyl units. The ladders are packed parallel to each other, and narrow channels are present due to insufficient space filling of the biphenyl rings. Its magnetic behavior follows that of a Bleaney–Bowers singlet-triplet model with a gap of 470(10) K.
Half-Metallocene 1-Aza-1,3-butadiene Complexes of Tantalum: Auxiliary Ligand Effects on Controlling Coordination Modes of 1-Aza-1,3-butadiene Ligand
Authors: Matsuo Yutaka , Mashima Kazushi , Tani Kazuhide
Published: September 2002

We prepared some half-metallocene complexes of tantalum bearing ortho-substituted aryl derivatives of 1-aza-1,3-butadiene ligand. The coordination mode of the 1-aza-1,3-diene (abbr. AD) ligand highly depended on the substituent(s) on the aryl group of the AD ligand and also on the metal center. The number of methyl substituents on the aryl group of the AD ligand differentiated two coordination modes: one methyl substituent, TaCl2Cp*(η4-supine-o-Tol-AD) (1) (Cp* = pentamethylcyclopentadienyl; o-Tol-AD = 1-(2-methylphenyl)-4-phenyl-1-aza-1,3-butadiene), favored an η4-supine-coordination mode, while two methyl substituents, TaCl2Cp*(η2-C, N-Xyl-AD) (5) (Xy1-AD = 2,6-dimethylphenyl-4-phenyl-1-aza-1,3-butadiene), adopted an η2-C, N-imine coordination fashion. Furthermore, the preferential coordination mode of the AD ligand was delicately affected by the substituent(s) on the tantalum center. Dialkylation of 1 led to the formation of TaR2Cp*(o-Tol-AD) (6: R = Me; 8: R = CH2Ph) in the dimethyl complex 6. The equilibrium between η4-coordination mode and η2-C, N-coordination one was observed and the latter mode was thermally more feasible in solution and as solid state, and the o-Tol-AD ligand predominantly coordinated in an η2-C, N-imine fashin to the tantalum center of 8. In contrast, the monobenzylation of 1 did not change the η4-supine coordination mode, giving a monobenzyl complex Cp*TaCl(CH2Ph)(η4-supine-o-Tol-AD) (9). The dibenzyl complex 8 gradually turned to a benzylidene complex Ta(=CHPh)Cp*(η4-supine-o-Tol-AD) (10) on heating at 70 °C with the change of the coordination mode from η2 to η4. Introduction of a 1,3-butadiene ligand to the metal center gave a mixed-ligand complex TaCp*(η2-C,N-o-Tol-AD)(η4-s-cis-1,3-butadiene) (12), in which the metal center adopted an η2-C,N-fashion.
Size Distribution of Dew Droplets and Dew Formation Effect on Deposition Fluxes
Authors: Takeuchi Masaki , Hasegawa Tetuo , Okochi Hiroshi , Igawa Manabu
Published: September 2002

Dew droplets have a distribution of sizes up to 1.5 mm diameter. Large-sized droplets controlled the dewwater amount and the number of small-sized droplets decreased during the evaporation process. The wetting by dew formation enhances the dry deposition of air pollutants.
Synthesis of Methyl O-α-D-Mannosyl-(1→4)-[(3-O-methyl-α-D- mannosyl)-(1→4)-]n3-O-methyl-α-D-mannosides (n = 0, 1, and 2) via Dehydrative Glycosylation
Authors: Hirooka Motoko , Terayama Megumi , Mitani Emi , Koto Shinkiti , Miura Asako , Chiba Kayo , Takabatake Ayano , Tashiro Takako
Published: September 2002

Methyl O-α-D-mannopyranosyl-(1→4)-[(3-O-methyl-α-D-mannopyranosyl-(1→4)-]n3-O-methyl-α-D-mannopyranosides (n = 0, 1, and 2), the lowest homologs related to the 3-O-methylmannose polysaccharides (MMP) from Mycobacterium smegmatis, were synthesized via dehydrative glycosylation reactions. The reagent systems, composed of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine, of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and 1, 8-diazabicyclo[5.4.0]undec-7-ene, and of trimethylsilyl trifuloromethanesulfonate and pyridine were useful.
New Dolabellane-Type Diterpenoids from the Okinawan Soft Coral of the Genus Clavularia
Authors: Iguchi Kazuo , Sawai Hisako , Nishimura Hiroto , Fujita Minako , Yamori Takao
Published: September 2002

Two new diterpenoids, 2 and 4, having a dolabellane skeleton were isolated from the Okinawan soft coral of the genus Clavularia. Their structures were determined based on spectroscopic analysis, chemical conversion and X-ray crystallographic analysis. One of these diterpenoids showed cytotoxic activity against tumor cells.
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

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

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

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

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

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

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

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

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

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

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

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.
Catalytic and Selective Conversion of Glycine into Serine by the Reaction with Formaldehyde in a Neutral Aqueous Solution
Authors: Yashiro Morio
Published: September 2002

Di- or trinuclear Cu(II) complexes efficiently catalyzed the condensation of glycine with formaldehyde to yield serine at pH 7.3, 50 °C.
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

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

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

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

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

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

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

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

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.
Theoretical Study on the Mechanism of Catalysis of Coenzyme B12-Dependent Diol Dehydratase
Authors: Eda Masataka , Kamachi Takashi , Yoshizawa Kazunari , Toraya Tetsuo
Published: September 2002

The energy profile of the diol dehydratase reaction is discussed from theoretical calculations at the B3LYP/6-311G* level of density functional theory. The differences between the energy diagrams of models with and without K+ ion are rather small except for the substrate binding and the OH group migration. The most important role of K+ ion in the diol dehydratase catalysis is to fix substrates and intermediates in proper positions in order to ensure the hydrogen abstraction and recombination between them and the adenosyl group. In the course of the reaction, substrates and reaction intermediates would always be kept bound to K+ ion until the release of product aldehyde from the active site. Given the neutral radical state of the substrate, the OH group migration proceeds in a concerted mechanism. In this process, K+ ion can work as an inhibitor of intramolecular hydrogen bond, which decreases the activation energy by 4.0 kcal/mol, due to the destabilization of reactant 1,2-dihydroxypropyl radical. The lowering of the activation energy by K+ ion, however, is rather small, and thus the contributions of active-site amino acid residues to the OH group migration must be taken into consideration to explain that the hydrogen abstraction is the rate-determining step for the overall reaction.
Study of the Reactions of O- with CF4 and CHF3 by Ab Initio Calculations
Authors: Yamamoto Mitsuo , Yamashita Koichi , Sadakata Masayoshi
Published: September 2002

Previous experiments on the reactions of O- with CF4 and CHF3 using a selected ion flow tube (SIFT) have indicated that many species, such as CF3-, F-, and HF2-, are produced in the O- + CHF3 reaction, although no reaction proceeds in the O- + CF4 reaction under thermal conditions. Ab initio molecular orbital calculations were carried out in this study to clarify the reason for the difference in the reactivity between these two reactions. Potential energy surfaces (PESs) for the possible reaction channels were computed at the UMP2/6-31+G** level. Although the SN2-type reactions, such as the CF3O- + F channel, are exothermic, the calculated activation energy for the O- + CF4 reaction is rather high, 222 kJ/mol. The energies of the transition states in the O- + CHF3 reaction are below that of the reactant. We may conclude that the difference in reactivity between the two reactions is attributable to the charge distribution of each molecule. The H atom in CHF3 has a large effect on increasing the reactivity because the positively charged H atom attracts O-, whereas O- has difficulty approaching the CF4 molecule because of the four negatively charged F atoms.
Electrochemical-ESR Detection of Hydrogen Atom Adducts of 5-Membered Ring Nitrone Spin Traps
Authors: Endo Nobuyuki , Higashi Kousuke , Kanaori Kenji , Tajima Kunihiko , Makino Keisuke
Published: September 2002

In order to make the spin trapping technique more useful in biological free radical studies, using an specially designed ESR cell for in situ electrochemical reactions, five 5-membered ring nitrones, which are analogues of 5,5-dimethyl-1-pyrroline N-oxide (DMPO), one of the most conventionally used spin traps, have been explored for their hydrogen atom (•H) adducts formation. ESR spectra consisting of only •H adducts and the resulting ESR parameters are discussed.
Spectroscopic and Structural Studies on Adsorption of Azo Dye in Cationic Langmuir–Blodgett Films
Authors: Ray Krishanu , Nakahara Hiroo
Published: September 2002

The monolayer properties of octadecylamine at various pHs on the Naphthalene Red (NR) aqueous solution were studied from the measurements of surface pressure–area isotherms. It was observed that the presence of the azo dye substituted with the –OH group (NR) in the subphase affects the compressibility of the octadecylamine monolayer. The adsorbability of the cationic Langmuir–Blodgett (LB) films was investigated by NR as an adsorbate. The cationic LB films before and after the azo dye adsorption were characterized by UV–vis absorption and emission spectroscopy, polarized visible absorption, X-ray diffraction, FTIR spectroscopy, and atomic force microscopy. Strong dipole–dipole interaction between the NR molecules in functionalized LB films was observed in accordance with the exciton model. It was found that the adsorption of the azo dye induced rearrangement of the layer structure of the cationic LB films where the hydrocarbon chains of the amine molecules exhibited an interdigitated structure and the azo dye molecules adsorbed in the LB films were oriented in an edge-on configuration. Furthermore, the substituent position of the –OH group of NR plays a crucial role in the different ways on the orientation of the other azo dyes in organized assembly.
Anisotropic Intermolecular Interactions and Through-Space/Through-Bond Intramolecular Interactions Observed by Collision-Energy-Resolved Penning Ionization Electron Spectroscopy
Authors: Kishimoto Naoki , Ogasawara Hideyuki , Ohno Koichi
Published: September 2002

Ionization of 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,4-cyclohexadiene (CHD), and 2,5-norbornadiene (NBD) with He*(23S) metastable atoms was studied by (collision-energy/electron-energy-resolved) two-dimensional Penning ionization electron spectroscopy. Anisotropic interaction around the molecule was investigated by determining collision energy dependence of partial ionization cross sections (CEDPICS) and spatially anisotropic distribution of ionized molecular orbitals (MOs). The negative slope of CEDPICS for HOMO was smaller than that for the next HOMO of DABCO and CHD; this was due to the repulsive interaction around the σCC,CH bond region, which is related to the through-bond interaction via the electron distribution. The trend of CEDPICS for DABCO was confirmed by classical trajectory calculations. For NBD, the negative CEDPICS for the next HOMO was larger than that for HOMO; this was due to the attractive endo region for the in-phase next HOMO with the through-space interaction.
A Facile Preparation of 5-Isopropylidene-3,8-dimethyl-1(5H)-azulenone and Its Crystal Structure
Authors: Takekuma Shin-ichi , Jyoujima Syougo , Sasaki Masato , Matsumoto Takuya , Fukunaga Hideo , Takekuma Hideko , Yamamoto Hiroshi
Published: September 2002

Oxidation of 5,5′-biguaiazulene-3,3′(5H,5′H)-dione (2) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in CH2Cl2 at 25 °C under aerobic conditions rapidly gives the title compound, 5-isopropylidene-3,8-dimethyl-1(5H)-azulenone (4), in 52% isolated yield. The crystal structure of 4 is reported as the first example for azulenequinonemethides.