bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Facile Method for the Production of d-p-Hydroxyphenylglycine. Asymmetric Transformation of Dl-p-Hydroxyphenylglycine Using (+)-1-Phenylethanesulfonic Acid
Authors: Yoshioka Ryuzo , Tohyama Masanori , Yamada Shigeki , Ohtsuki Osamu , Chibata Ichiro 
Published: July 2006

Abstract
A practical method for the production of d-p-hydroxyphenylglycine, useful as a starting material for preparing semisynthetic penicillins or cephalosporins, has been developed. The diastereomeric salts of Dl-p-hydroxyphenylglycine with (+)-1-phenylethanesulfonic acid as a resolving agent, were efficiently resolved into less soluble d-p-hydroxyphenylglycine (+)-1-phenylethanesulfonate [d-HPG·(+)-PES] and soluble l-HPG·(+)-PES by the fractional crystallization of its salts in aqueous solution. The soluble l-HPG·(+)-PES could be easily epimerized into Dl-HPG·(+)-PES by heating it with water containing a 0.1 molar equivalent of free Dl-HPG in an autoclave. When the fractional crystallization of Dl-HPG with (+)-PES was simultaneously carried out under the epimerizing conditions, the Dl-HPG·(+)-PES was transformed into d-HPG·(+)-PES in up to 90% yield. The present asymmetric transformation should be a suitable method for preparing d-HPG in a large scale.
Preparation of Polyacetoxytropones and Polyhydroxytropolones by Acetolysis and Hydrolysis of Halotroponoids by Acetyl Trifluoroacetate with Exhaustive Displacement of Halogens on the Tropone Ring. Predominant Formation of Reductive Acetolysates from Fully-Substituted Tropones
Authors: Takeshita Hitoshi , Mori Akira , Kusaba Tomoyuki , Watanabe Hiroyasu 
Published: July 2006

Abstract
Di-, tri-, and tetrahydroxytropolones were prepared in good yields by the acetolysis of corresponding halotropones or polyhalotropolones with acetyl trifluoroacetate followed by acetic acid hydrolysis. However, using the same treatment to obtain hexaacetoxytropone with fully substituted acetoxyhalotropones predominantly yielded fewer substituted acetoxytropones than expected; the mechanism of formation was shown to involve an acetic acid-mediated reduction of intermediary formed acetoxy-p-tropoquinone equivalents. A couple of 2,7-unsubstituted 3,4-diacetoxytropones were deduced to have cyclized 1,3-dioxole structures, 2-acetoxy-2-methyl-5H-cyclohepta-1,3-dioxol-5-ones. An acetolysis of the brominated 5-isopropyltropolones furnished an acetylated by-product, 2,3,7-triacetoxy-5-(1,1-dimethyl-2-oxopropyl)tropone, which might be formed by the acylation of an intermediate, 3,4,5,6-tetraacetoxy-8,8-dimethylheptafulvene.
Convenient Synthesis of Alkanediyl Bis(alkyl trithiocarbonate)s from Alkanedithiols with Alkyl Halides and Carbon Disulfide in the Presence of Phase-Transfer Catalyst
Authors: Sugawara Akira , Hasegawa Ken , Suzuki Ken-ichi , Takahashi Yukio , Sato Ryu 
Published: July 2006

Abstract
Alkanediyl bis(alkyl trithiocarbonate)s were conveniently synthesized by treating alkanedithiols with alkyl halides and carbon disulfide in the presence of a phase-transfer catalyst.
Reactions of Aryl Ketones and Coumarins with Iodine(III) Tris(trifluoroacetate)
Authors: Fukuyama Norihiro , Nishino Hiroshi , Kurosawa Kazu 
Published: July 2006

Abstract
The reaction of acetophenones with iodine(III) tris(trifluoroacetate) yields 3′- and/or 2-iodo derivatives, depending upon the substituent on the aromatic ring and the reaction conditions. The reaction was examined by changing the molar ratio of acetophenone versus the reagent, reaction temperature, and solvent. In similar reactions flavanones and coumarins gave iodo derivatives in which iodine is incorporated at various positions orientated by the oxygen functions. 1,2-Diphenylethanone yields 2-hydroxy-2-(2-iodophenyl)-1-phenylethanone and 1-(2-iodophenyl)-2-phenylethanedione. The reactions of other aromatic ketones such as 9-xanthenone, 9-fluorenone, and anthrone also give iodo derivatives in moderate to good yields. The mechanisms for the iodination at the α-carbon to the carbonyl group have been discussed.
Efficient Carbonyl Addition of Polyfluorochloroethyl, -ethylidene, and -ethenyl Units by Means of 1,1,1-Trichloro-2,2,2-trifluoroethane and Zinc
Authors: Fujita Makoto , Hiyama Tamejiro 
Published: July 2006

Abstract
Thermally stable zinc carbenoid CF3CCl2ZnCl was prepared from 1,1,1-trichloro-2,2,2-trifluoroethane and zinc powder in N,N-dimethylformamide and was allowed to add to carbonyls of aldehydes and α-keto esters in excellent yields to give 1-substituted 2,2-dichloro-3,3,3-trifluoro-1-propanols. Employment of excess zinc induced further reductive β-elimination to afford 1-substituted 2-chloro-3,3,3-trifluoropropenes (3) and 1-substituted 2-chloro-3,3-difluoro-2-propen-1-ols (4). Exclusive formation of 3 was achieved by use of acetic anhydride as the co-reagent, whereas 4 was produced with an aluminium chloride catalyst highly selectively.
Spectral Characteristics of Phenylenediamines and Their Various Protonated Species
Authors: Manoharan R , Dogra Sneh Kumar 
Published: July 2006

Abstract
Increase in the Stokes shift [\barνabs(max)−\barνflu (max)] with an increase in the polarity and hydrogen-bonding capacity of the solvents is the maximum for p-phenylenediamine and the minimum for m-phenylenediamine. These studies have indicated that the two amino groups in o- and p-phenylenediamines are not in the same plane of the benzene ring. Spectral characteristics of monocations and dications resemble to those of aniline and benzene respectively. pKa values for the dication–monocation and monocation–neutral equilibria have been determined, both in S0 and S1 states, and discussed.
Mass Spectral and Pyrolytic Studies of Some 4,4-Disubstituted 1,4-Dihydro-2H-3,1-benzoxazin-2-ones
Authors: Acharya Baman Prasad , Misra Bijaya Kumar , Rao Yerramalli Ramachandra 
Published: July 2006

Abstract
Pyrolysis of 4,4-diaryl-1,4-dihydro-2H-3,1-benzoxazin-2-ones at 230–240 °C gives 9-arylacridines and (2-aminophenyl)diarylmethanes. Their formation correlates well with the mass fragmentation of the respective parent compounds.
Adsorption of Cu2+ or Hg2+ Ion on Resins Prepared by Crosslinking Metal-Complexed Chitosans
Authors: Ohga Kazuya , Kurauchi Yoshiaki , Yanase Hiroshi 
Published: July 2006

Abstract
Crosslinking metal-complexed chitosans (metal ions=Cu(II), Cd(II), Zn(II), Ni(II), and Fe(III)) with (chloromethyl)oxirane yields resins having higher abilities to adsorb Cu2+ than a resin obtained from chitosan in the absence of metal ion. Resins from Cd(II)–chitosan complex can act as effective adsorbents for Hg2+; their Langmuir’s adsorption parameters depend on the quantity of (chloromethyl)oxirane used.
Effect of Catalyst on the Oxygenation of Styrene with BH4− and Molecular Oxygen
Authors: Okamoto Tadashi , Sasaki Yoshihiro , Sasaki Ken , Oka Shinzaburo 
Published: July 2006

Abstract
The effects of equatorial ligands and central metals on the catalytic conversion of styrene to 1-phenylethanol were examined. Accompanying hydrogenation and hydrodimerization of the substrate to ethylbenzene and 2,3-diphenylbutane, respectively, was facilitated in the presence of a catalyst ligated with an electron-releasing ligand such as 1,4,8,11-tetraazacyclotetradecane or sulfurcontaining ligands.
Formation of Chlorosulfonium Salt of 1,5-Dithiacyclooctane and Transannular Sulfur–Sulfur Interaction in Hydrolysis of Its Salt
Authors: Fujihara Hisashi , Akaishi Ryouichi , Furukawa Naomichi 
Published: July 2006

Abstract
The reaction of 1,5-dithiacyclooctane 1-oxide (2) with thionyl chloride afforded the corresponding chlorosulfonium chloride as a stable salt and an evidence for the intermediary formation of the bis-sulfide dication with an equilibrium mixture of the chlorosulfonium salt was found. In contrast to 2, 1,4-dithiacyclohexane 1-oxide (6) reacts with thionyl chloride like a simple sulfoxide.
Terpenoids. X. Natural Autoxidation of Thujopsene
Authors: Nagahama Shizuo , Tazaki Masato 
Published: July 2006

Abstract
The natural autoxidation of thujopsene 1 afforded three dimeric peroxides (14,15, and 16) as the major products. 9α,10-Epoxy-8α-thujopsanol 17 was separated as a minor product besides other known compounds, allylic alcohols 2 and 3, mayurone 7, thujopsane-8α,9α-diol 11, and thujopsan-9-ones 19 and 20.
Low Temperature Synthesis of Dispersed Fine Particle of Cobalt Aluminate—A New Application of Zeolite
Authors: Ohgushi Tatsuo , Umeno Shigeru 
Published: July 2006

Abstract
CoAl2O4, with the spinel structure in a dispersed form, was synthesized at 400 °C by using zeolite A as a starting material. A specific surface area of the products was measured by adsorption of (CH3)2CHCH3 gas at −110 °C and the mean size of the product particles was estimated to be about 14 nm.
Excited-State Reactions of Coumarins in Aqueous Solutions. V. Fluorescence Lifetimes of 7-Ethoxycoumarin in Acidic Solutions
Authors: Moriya Tetsuo 
Published: July 2006

Abstract
The fluorescence lifetime of 7-ethoxycoumarin (7EC) was measured in acidic aqueous solutions while varying the concentration of Cl− as a fluorescence quencher. The subsequent analysis of the two-component fluorescence decay curves indicated that the protonated species in the excited state led to the fluorescence quenching; this result was quantitatively consistent with the fluorescence-yield study under steady-state conditions.
Preparation of Noble Metal Organosols Containing Polyethylene Glycol Mono-p-nonylphenyl Ether
Authors: Nakao Yukimichi , Kaeriyama Kyoji 
Published: July 2006

Abstract
Stable organosols of ruthenium, rhodium, palladium, and platinum were prepared by evaporating the corresponding noble metal hydrosols containing nonionic surfactant, polyethylene glycol mono-p-nonylphenyl ether, followed by dissolving the resulting residues in organic solvents such as chloroform. The organosol of the noble metals was exclusively yielded at a definite range of the surfactant concentration. A mechanism for the formation of the organosols is proposed.
Acridine Derivatives. I. Molecular Structure of the Novel Acridinyl-Substituted Uracil, 5-(9-Acridinyl)-6-amino-1,3-dimethyluracil
Authors: Kimura Michio 
Published: July 2006

Abstract
The reaction of enamine between 9-chloroacridines and 6-aminouracil derivatives give novel acridine substituted uracils, the structures of which have been determined by means of an X-ray analysis of 5-(acridin-9-yl)-6-amino-1,3-dimethyluracil hydrochloride dihydrate, C19H16N4O2·HCl·2H2O. The crystal is triclinic with a space group P\bar1; also, a=8.763(3) b=16.130(9), c=7.620(2) Å, α=117.51(4), β=83.81(3), γ=94.21(4)°, Z=2, V=949.3 Å3, Dc=1.16 g cm−3, and μ=5.30 cm−1 for CuKα. The structure was solved by a direct method and refined by a block-diagonal least-squares procedure: R=0.074 for 2810 reflections with |Fo|&gt;3σ(|Fo|). The crystal is composed of the title compound, chloride anion, and two molecules of water held together by hydrogen bonds (described in Table 4).
Studies on 5-8 Fused Ring Compounds. IV. The Syntheses of 5-8-5 Fused Ring Compounds and the Conformations of Their Eight-Membered Rings
Authors: Umehara Misao , Hishida Shinzaburo , Okumoto Satoshi , Ohba Shigeru , Ito Masatoki , Saito Yoshihiko 
Published: July 2006

Abstract
The isomers, cis-cisoid-cis- and cis-transoid-cis-tricyclo[9.3.0.04,8]tetradecane-2,9-dione (2 and 3) and cis-cisoid-cis-tricyclo[9.3.0.03,7]tetradecane-2,9-dione (4) were synthesized by the photocycloaddition of bicyclo[4.3.0]nonane-2,4-dione (1) to cyclopentene. X-Ray analyses of those compounds revealed that the conformations of the eight-membered rings are twist-boat in 2, chair in 3, and boat–chair form in 4.
X-Ray Structure and Magnetism of μ-Bromo-μ-pyrazolatobis(diethylenetriaminecopper(II)) Perchlorate Monohydrate
Authors: Matsumoto Keiji , Ooi Shun’ichiro , Mori Wasuke , Nakao Yasuo 
Published: July 2006

Abstract
The structure of the title compound has been determined by an X-ray method. The dinuclear complex is composed of two Cu(dien) units which are bridged by pyrazolate and Br− anions. The geometry around each copper(II) may be described as a square pyramid. The antiferromagnetic interaction within the dinuclear complex has been observed (J=−14 cm−1, H=−2JS1·S2).
Some Applications of Thermodynamic Equations on the Pressure Effect of the Chemical Reactions
Authors: Jee Jong-Gi 
Published: July 2006

Abstract
This paper is concerned with the theoretical derivation of the linear relationship between enthalpy and entropy for pressure change in chemical equilibria, and its application to the dissociation equilibria of some 4-substituted 1-methylpyridinium iodides in water–ethanol mixture. The isoequilibrium temperature, \barβ, for this system was derived to be 322 K.
Reduction of Nitrostyrenes to Nitroalkanes with a NADH Grafted Model
Authors: Tréfouel Thierry , Tintillier Patrik , Dupas Georges , Bourguignon Jean , Quéguiner Guy 
Published: July 2006

Abstract
Grafting of the 1,4-dihydronicotinamide structure on a Merrifield type resin is described. With this reagent, arylnitroethanes have been obtained by regioselective reduction of β-nitrostyrenes. The yields are good and no dimeric compounds are formed. The role of magnesium ions in these reductions is different from that observed with classical NADH models.
Molecular Dynamics Simulation of Liquid Water
Authors: Tokiwano Kazuo , Arakawa Kiyoshi 
Published: July 2006

Abstract
A molecular dynamics simulation has been performed for a fluid system containing 1000 water molecules confined to a cubical box at mass density 1 g cm−3, where the ST2 type intermolecular potential has been used. Newtonian equations of motion of molecules were solved according to the method of constraints proposed by Ryckaert et al. Atomic radial distribution functions and corresponding partial structure functions at 24 and 93 °C were given and compared with theoretical calculations for the pentamer–monomer mixture model and neutron diffraction data. The agreement among the three was found to be satisfactory on the whole. In order to investigate how profoundly the periodic boundary condition influences upon the calculated values, the difference between the hydrogen-bonding behavior of molecules near the boundary and that of those in the central part of the box was examined into details. The population of hydrogen bonds near the boundary was found to be about 10% lower than that in the central part including about 210 molecules. In addition to these static properties the self-diffusion process was investigated.
An ENDOR Study of Diphenyl Nitroxide and Its Methyl Derivatives, The Effect of the Methyl Substitution
Authors: Yamauchi Jun , Okada Keiichi , Deguchi Yasuo 
Published: July 2006

Abstract
The ENDOR spectra of diphenyl nitroxide (DPNO) and its monomethyl derivatives were observed in ethylbenzene at −70 °C. The agreement between the ESR and ENDOR data is generally good. The MO calculations, however, indicate a few disagreements in the case of the m- and o-methyl DPNO derivatives. The methyl substitution at the meta-position destroys the equivalency of all protons at the meta-positions, which are divided into two sets of equivalent proton groups of the same number. The ortho-substitution weakens the coplanarity of the two benzene rings and increases the number of the equivalent proton groups, which are fully resolved in the ENDOR spectrum. The steric hindrance is taken into account in the MO calculation, which can predict these slightly different coupling groups-again except for those in the meta-positions. A satisfactorily simulated spectrum of the o-methyl DPNO is obtained on the basis of the ENDOR data.
Time-Resolved Unimolecular Reactions of Pyridine Ions by Means of Trapped-Ion Mass Spectrometry
Authors: Arakawa Ryuichi , Yoshikawa Yozaburo 
Published: July 2006

Abstract
The electron-impact ionization-efficiency curves for the C5H5N+·→C4H4+·+HCN dissociation have been measured as a function of the ion-source-residence time by means of trapped-ion mass spectrometry (TIMS). The ionization-efficiency curves for residence times of 5 and 700 μs were fitted by QET calculation, assuming dissociation-rate models. A kinetic shift of 0.3 eV was observed from the time-dependent appearance energy measurements. The fragmentation of metastable ions was first sampled for the ion-source residence time of 0–100 μs. The preferable rate model was determined by the analysis of the ionization-efficiency curves and the metastable ion fragmentations. Time-resolved kinetic energy releases for pyridine and perdeuteriopyridine have been explained in terms of excess energy drop of metastable ions with their lifetime.
The Structure of the Cyclodextrin Complex. XIX. Crystal Structures of Hexakis(2,3,6-tri-O-methyl)-α-cyclodextrin Complexes with (S)- and (R)-Mandelic Acid. Chiral Recognition through the Induced-Fit Conformational Change of the Macrocyclic Ring
Authors: Harata Kazuaki , Uekama Kaneto , Otagiri Masaki , Hirayama Fumitoshi 
Published: July 2006

Abstract
Hexakis(2,3,6-tri-O-methyl)-α-cyclodextrin (methyl-α-CDx) forms crystalline inclusion complexes with (S)-mandelic acid (S-MA) and (R)-mandelic acid (R-MA). Both crystals are monoclinic, and the space group is P21 with cell dimensions: a=13.123(2), b=23.187(4), c=13.113(2) Å, β=107.19(1)° for the S-MA complex, a=11.624(2), b=23.739(4), c=13.786(2) Å, β=106.56(1)° for the R-MA complex. The structures were solved by inspection of a Patterson map and the R-map method, and refined by the block-diagonal least-squares method to the R-values of 0.087 for the S-MA complex and 0.055 for the R-MA complex. In the S-MA complex, the methyl-α-CDx molecule, which has a pseudo two-fold symmetry, loosely includes the phenyl group of S-MA. The hydroxyl and carboxyl groups of S-MA protrude from the O(2), O(3) side of the methyl-α-CDx cavity and form hydrogen bonds with water molecules located outside the host cavity. The methyl-α-CDx molecule in the R-MA complex tightly binds the R-MA molecule which is deeply inserted into the host cavity. The hydroxyl group of R-MA is hydrogen-bonded to an O(2) oxygen atom of host methyl-α-CDx. The comparison of the two structures suggests that the complex formation induces the conformational change of the host molecule to accommodate S-MA or R-MA more suitably within the cavity.
The Vaporization of the Various Trace Components from Aluminoborosilicate Glass
Authors: Itoh Noriko , Nakamura Tetsur\={o} 
Published: July 2006

Abstract
The simultaneous vaporization of dopants in aluminoborosilicate glass was investigated by means of mass spectrometry using a Knudsen cell. The detected chemical species were Na, K, Ni, Zn, Rb, Ag, Te, TeO2, and Cs in the temperature range of 650–800°C. Their vapor pressures were 10−6–10−4 Pa. The activation energy of vaporization was discussed in relation to the electrostatic force between the vaporizing specie and oxygen. However, lithium, alkali-earth metal elements, alomst all the transition metal elements (such as Fe, Cr, and Ru), and rare-earth metal elements were not detected in the vapor phase, though they were contained in the glass matrix.
The Solvent Extraction of Alkali and Alkaline Earth Metal Ions with Nonionic and Ionic Surfactants Having Poly(oxyethylene) Chain
Authors: Sakai Yukio , Shinmura Masahiro , Otsuka Hajime , Takagi Makoto 
Published: July 2006

Abstract
Extraction behavior of alkali and alkaline earth metal cations was investigated with a new extractant derived from polyethylene glycol mono[4-(1,1,3,3-tetramethylbutyl)phenyl]ether (Triton X-100; average number of oxyethylene group, 10) by introducing a phenolic(2-hydroxy-5-nitrobenzyl) group at the hydroxyl terminal of the polyethylene glycol chain. Alkali metal cations were extracted into 1,2-dichloroethane by forming 1:1 complex with the extractant. The overall extraction constant sequence was K+(10−9.15)&gt;Rb+(10−9.26)&gt;Cs+ (10−9.28)&gt;Na+ (10−10.08)&gt;Li+(10−10.36). The selectivity for K+, Na+, and Li+ was discussed by comparing the extraction behavior with a mixture of nonionic surfactant or dicyclohexano-18-crown-6 and a proton-dissociable lipophilic dye. For alkaline earth metal cations, the extractability decreased in the order Ba2+&gt;Sr2+&gt;Ca2+&gt;&gt;Mg2+. The metal extractability strongly depended on the nature of the anion in the aqueous phase.
Vapor-Phase Amination of Cyclohexanol over Silica-Supported Platinum Group Metal Catalysts
Authors: Hamada Hideaki , Kuwahara Yasushi , Sato Takahiro , Wakabayashi Katsuhiko 
Published: July 2006

Abstract
Vapor-phase amination of cyclohexanol with ammonia over silica-supported platinum and other platinum group metal (Ru, Rh, Pd, Ir) catalysts has been studied. Cyclohexylamine and aniline are the main products. Platinum is the most active metal, although there is not much difference in the activity between platinum and other metals. The reaction is suggested to proceed as follows. The first step, which is rate-determining, is the dehydrogenation of cyclohexanol to cyclohexanone intermediate, from which cyclohexylamine and aniline are formed in the parallel process via cyclohexylideneamine. From reaction-rate measurements on Pt/SiO2 catalysts with different Pt particle size, the amination reaction has been found to be structure-insensitive. The catalytic activity decreases with time on stream probably because of the deposit of carbonacious or polymeric materials on the catalyst surface.
ESR Studies of a New 3dz2-Type Copper(II)–Crown Ether Complex with Pentagonal Bipyramidal Geometry
Authors: Li Yong , Tajima Kunihiko , Ishizu Kazuhiko , Azuma Nagao 
Published: July 2006

Abstract
In the presence of the optimum amount of water, the copper(II) ion and 15-crown-5 (15C5) derivatives gave the dihydrated complex in boron trifluoride–diethyl ether (BF3–ether). Based on optical and ESR spectrometric titrations, we found that the crown ether captures the copper(II) ion in the equivalent metal/ligand molar ratio. The d–d band absorptions of the complexes were detected in the near-infrared region. The complexes revealed the characteristic ESR g-anisotropies (gz&lt;gx, gy) which are typical of the copper(II) complexes with a 3dz2 ground-state doublet. The superhyperfine splittings due to the 17O isotope was successfully detected, and the fact of the axial ligation of the water molecule was demonstrated. The ESR parameters were determined by means of the computer simulation of the line shape, while the copper-ligand bonding parameters were estimated from the ESR parameters by means of Bleaney’s calculation.
Redox Reactions of cis-Dialkylcobalt(III) Complexes with Benzyl and Allyl Bromides, Induced by Thermal Cleavage of the Cobalt–Carbon Bond
Authors: Ishikawa Kunio , Fukuzumi Shunichi , Tanaka Toshio 
Published: July 2006

Abstract
The thermal cleavage of the cobalt–carbon bond of cis-dialkylcobalt(III) complexes, cis-[R2Co(bpy)2]+(R=Me, Et, and PhCH2; bpy=2,2′-bipyridine), was enhanced by the presence of benzyl and allyl bromide, inducing the C–C bond formation to yield mainly 1,2-diphenylethane and 1,5-hexadiene, respectively. In the cis-[(PhCH2)2Co(bpy)2]+-allyl bromide system, a comparable amount of the cross-coupling product (4-phenyl-1-butene) was obtained together with the homo-coupling products (1,2-diphenylethane and 1,5-hexadiene). The enhancement of the thermal cleavage of the cobalt–carbon bond of cis-[R2Co(bpy)2]+ by the reactions with benzyl and allyl bromides is caused by the high reactivity of the carbanion ligand of [RCo(bpy)2]+ produced by the homolytic cleavage of the cobalt–carbon bond of cis-[R2Co(bpy)2]+, which undergoes the exchange, coupling, and cross-coupling reactions with benzyl and allyl groups of the bromides. Based on the kinetics and the activation parameters, the cobalt–carbon bond dissociation enthalpy of cis-[(PhCH2)2Co(bpy)2]+ has been estimated to be 92 kJ mol−1.