bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Microwave Spectrum, the rs Structure and the Dipole Moment of the TT Isomer of Diethyl Ether
Authors: Hayashi Michiro , Kuwada Kazunori 
Published: July 2006

Abstract
The microwave spectra of six isotopic species of diethyl ether were measured in relation to the molecular form and dipole moment. Transitions of the TT(trans-trans) isomer could be assigned and the rs structure of this isomer was obtained by the substitution method. The structural parameters of the TT isomer of diethyl ether are; r(CO) 1.408 Å, r(CC) 1.516 Å; α(COC) 112°25′, α(OCC) 108°37′ for the skeleton; r(CH) 1.093 Å, α(CCH) 110°11′, α(OCH) 110°10′, α(HCH) 107°29′ for the CH2 group and r(CH) 1.090 Å, α(CCHs) 110°35′, α(CCHa) 110°15′, α(HsCHa) 108°48′, α(HaCHa) 108°4′ for the CH3 group. The dipole moment was determined to be 1.061±0.018 D from the Stark effect measurement for the TT isomer. A discussion was made on the structure and the dipole moment of the TT isomer of diethyl ether in comparison with those of the similar molecules.
Transition-metal Complexes of Pyrrole Pigments. X. Divalent and Trivalent Manganese Chelates of Dipyrromethenes
Authors: Murakami Yukito , Sakata Kazunori , Harada Kenji , Matsuda Yoshihisa 
Published: July 2006

Abstract
The solution spectra of two tris(dipyrromethenato)manganese(III) complexes and of one bis(dipyrromethenato) manganese (II) as well as the diffuse reflectance spectrum for the latter were examined. The high spin state was confirmed for all the manganese complexes by magnetic susceptibility measurements. For the tris-complexes, one broad low energy band (∼9500 cm−1) is assigned to the 5A1g←5B1g transition and one pair of higher energy bands (∼14000 cm−1) are attributed to the 5B2g←5B1g and 5Eg←5B1g transitions for a D4h symmetry as a consequence of Jahn-Teller effect. In the bis-complex, manganese(II) is placed in a tetrahedral ligand field and one group of ligand-field bands lying below 16000 cm−1 are assigned to: 4T1(4G)←6A1(6S), 4T2(4G)←6A1(6S), and 4E, 4A1(4G)←6A1(6S) in an increasing order of energy. The exceedingly high intensity of these bands is ascribed to the covalent nature of coordinate bonds. A strong IR band due to the skeletal stretching mode of the dipyrromethene moiety was observed in the 1600 cm−1 range and shifted slightly toward lower energy upon metalcoordination.
Nitrosylrhenium(14NO and 15NO) Complexes
Authors: Miki Eiichi , Mizumachi Kunihiko , Ishimori Tatsujiro 
Published: July 2006

Abstract
The 15NO-complexes for M2[ReX5(NO)] (M=Rb, Cs, and pyH; X=Cl and Br) were prepared. The 15N-isotopic shift for their N–O stretching vibrations, ca. 40 cm−1, supports the view that the oxidation state of the NO group is I, while that of the rhenium atom is II. The Re–(NO) stretching and the Re–(NO) bending vibrations were observed in the 610–620 cm−1 region. A new compound, cis-(pyH)[ReCl4(NO)2], was prepared, the oxidation state of its rhenium atom being considered to be I, and that of the NO group, I.
The Synthesis of Coenzyme Q
Authors: Inoue Seiichi , Yamaguchi Ryohei , Saito Kenji , Sato Kikumasa 
Published: July 2006

Abstract
A new, efficient synthesis of coenzyme Q is described. The bromination of 2,3-dimethoxy-5-methyl-p-benzoquinone gives 6-bromo-2,3-dimethoxy-5-methyl-p-benzoquinone, which is then converted to the corresponding hydroquinone diacetate by the action of zinc dust in acetic anhydride. 6-Bromo-2,3-dimethoxy-5-methylhydroquinone diacetate is reacted with 1,1-dimethyl-π-allylnickel bromide in hexamethylphosphoramide at 60 °C to afford a 70% yield of 2,3-dimethoxy-5-methyl-6-prenylhydroquinone diacetate, which is hydrogenolyzed with lithium aluminum hydride in ether and then oxidized with aqueous ferric chloride to give coenzyme Q1 in 76% yield. Similarly, coenzyme Q2, Q9, and Q10, and 6′, 10′, 14′-hexahydrocoenzyme Q4 are synthesized by the reaction of the aryl bromide with π-geranyl-, π-solanesyl-, π-decaprenyl-, and π-phytylnickel bromide respectively and by subsequent treatment with LiAlH4 and FeCl3. The stereochemistry of the products is also described.
Molybdenum(V) Chloride as a Reagent for cis Chlorination of Olefins
Authors: Uemura Sakae , Onoe Akira , Okano Masaya 
Published: July 2006

Abstract
Treatment of nonconjugated olefins such as cis- and trans-2-butenes, cis-2-octene, and cyclohexene with MoCl5 in CCl4 gave vic-dichloroalkanes whose cis-isomer was formed predominantly, the ratio of cis- to trans-addition being 4.9–12.1, together with monochloroalkanes. Preferential formation of exo-cis-dichloride was observed in the case of norbornene and norbornadiene. Bromochlorination and chloroiodination of olefins, and aromatic bromination and iodination were carried out with mixtures of MoCl5 and halogens. The reaction scheme for chlorination is discussed.
Studies on the Synthesis of Histidine Peptides. I. Nim-Tosylhistidine Derivatives as Starting Materials
Authors: Fujii Toshiyuki , Sakakibara Shumpei 
Published: July 2006

Abstract
N α-Nps-, Z(OMe)-, Z-, Boc-, and Aoc-derivatives of Nim-tosylhistidine were synthesized as materials for the syntheses of histidine-containing peptides, and the reactivity of the Nim-tosyl group was examined under several conditions commonly used for peptide syntheses. Although the Nim-tosyl group was somewhat more unstable than Nim-benzyl group, the use of the tosyl derivative was found to be advantageous in several points: the enhancement of the solubility of its peptide derivatives, the suppressive effect of racemization during its coupling reactions, and the high removability of the tosyl group under mild conditions.
On the Additivity of π-Bond Energies in Linear Polyenes
Authors: Aihara Jun-ichi 
Published: July 2006

Abstract
The additivity of π-bond energies in linear polyenes was confirmed by taking nonaromatic [infinity]-annulene and -polyene as reference compounds. The π-bond energies determined by Hess and Schaad were found to be oriented to polyenes of a medium size.
Photocycloaddition of Thiocarbonyl Compounds to Multiple Bonds. X. Photocycloaddition of O-Alkyl Thiobenzoates to Olefins
Authors: Ohno Atsuyoshi , Koizumi Tamotsu , Akasaki Yutaka 
Published: July 2006

Abstract
Photochemical reactions of O-ethyl and O-methyl thiobenzoates with various olefins have been studied. Some olefins afford ketones, others yield thietanes, and in some cases both products are obtained. Thiobenzoate O-esters in the n,π* triplet state are the reacting species. The mechanism of the reaction has been elucidated: photocycloaddition of a thioester to an olefin results in the formation of a thietane. Photosensitized decomposition of the thietane yields an α,β-unsaturated ether, which is converted to a ketone by general acid-catalyzed hydrolysis.
The Structure-Taste Relationships of the Dipeptide Esters Composed of l-Aspartic Acid and β-Hydroxy Amino Acids
Authors: Ariyoshi Yasuo , Yasuda Naohiko , Yamatani Tetsuo 
Published: July 2006

Abstract
In order to evaluate the contribution of a hydroxyl group to the degree of sweetness of aspartyl dipeptides, we have synthesized a number of α-l-aspartyl dipeptides, such as the esters of α-l-aspartyl-l-hydroxynorleucine (16 and 17), -O-acyl-l-serine (18–21), -d-serine (22–28), -d-threonine (30–36), and -d-allothreonine (37–43); their sweetness potencies were compared with those of the corresponding dipeptides without a hydroxyl group. It has been found that a hydroxyl group makes a major contribution to the sweetness of the α-l-aspartyl dipeptide esters. Trie introduction of a hydroxyl group into the l-l peptides gave compounds with reduced potency. However, no such regularity was observed in the l–d peptides; the esters of α-l-aspartyl-d-serine (22–28) and -d-threonine (30–36) were sweeter than the corresponding esters of α-l-aspartyl-d-alanine and -d-α-amino-n-butyric acid respectively, while the esters of α-l-aspartyl-d-allothreonine (37–43) were less sweet than the corresponding esters of α-l-aspartyl-d-α-amino-n-butyric acid. The enzymatic resolution of N-acetyl-erythro- and -threo-β-hydroxy-Dl-norleucine is also described.
The Oxidation of 1,3-Butadienes with Nitric Acid into 2,5-Dihydrofurans
Authors: Toda Fumio , Todo Eishiro 
Published: July 2006

Abstract
The oxidation of 3,4-bis(diphenylmethylene)-succinic anhydride (I), -1-benzylsuccinimide (VI), and -γ-butyrolactone (VIII) with nitric acid afforded the corresponding 2,5-dihydrofuran derivatives, III, VII, and IX respectively. The same oxidation of 3,4-bis(diphenylmethylene)cyclobutane-1,2-dione (XI) afforded 3,4-bis(diphenylhydroxymethyl)cyclobut-3-ene-1,2-dione (XIII), probably via the bicyclic cyclobutenedione intermediate (XII).
An ENDOR Study of the Relaxation Behavior of the Nuclei in Several Semiquinone Anion Radicals
Authors: Kotake Yashige , Kuwata Keiji 
Published: July 2006

Abstract
The ENDOR intensities of several semiquinone anion radicals were measured at various temperatures. The optimum temperature for the ENDOR intensity of protons in a radical was interpreted on the basis of their characteristic ways of relaxation. The electron nuclear dipolar (END) mechanism could be applied very well in most cases. However, in the case of protons whose END terms are very small this interaction might not explain the optimum temperature. Possible substitute mechanisms were discussed.
Dielectric Relaxation and Molecular Structure. IX. Dielectric Behavior of 1-Propanol and 1-Butanol in a Variety of Solvents
Authors: Koshii Taro , Arie Eiji , Nakamura Masahiko , Takahashi Hiroaki , Higasi Keniti 
Published: July 2006

Abstract
The dielectric constants and losses of 1-propanol and its mixtures with benzene, chlorobenzene, 1,4-dioxane or pyridine, and 1-butanol and its mixtures with benzene or pyridine have been measured in the frequency range of 0.35–2.1 GHz at 25.0 °C. Concentrations of alcohols are 1–0.6 mol fraction of the mixtures. Densities and refractive indices have also been determined. The dielectric data were used to calculate the relaxation times of the alcohols. The Cole-Cole plots for these systems showed Debye-type semicircles in lower frequencies where the principal relaxation of alcohols dominates. Deviations from the semicircle, however, have been observed in the region of upper frequencies, where the second dispersion of alcohol, the dispersion of solvent itself and of hydrogen-bonded species between alcohol and solvent may occur. The principal relaxation times of alcohols calculated from the data of lower frequencies change with concentration in two different manners by solvents, and this difference is due to whether the solvent has hydrogen-bonding capacity or not, and does not depend upon the dielectric constant and/or the polarity of the solvent.
The Reaction of Bis (2-pyridinecarbonitrile) copper(II) Chloride with Methanol and Various Amines
Authors: Suzuki Shinnichiro , Nakahara Masayoshi , Watanabe Ken-ichi 
Published: July 2006

Abstract
On treatment of bis(2-pyridinecarbonitrile)copper(II) chloride with various amines in methanol, the alkoxylation of the nitrile group in the complex took place; in some cases, the alkoxylation and the ligand substitution of the complex occurred at the same time. The reaction products were classified into three types depending on the amines used; two of the types consisted of new complexes. The complexes of CuCl2(MeOpy)(Amine) (MeOpy: O-methylpyridine-2-carboximidate), were obtained on the addition of ammonia, methylamine, dimethylamine, ethylamine, benzylamine, or piperidine to a methanol solution of bis(2-pyridinecarbonitrile)copper(II) chloride. On the other hand, the addition of trimethylamine, diethylamine, or triethylamine afforded the complex of CuCl2(MeOpy)2. These types of complexes were not obtained by the use of aniline or pyridine; but the previously known complex, CuCl2(MeOpy), was obatined in this case. It has been assumed that the formation of the three types of complexes is essentially the result of both the basicities and the steric factors of the amines.
Infrared Spectra of Nitrosylplatinum (14NO and 15NO) Complexes
Authors: Miki Eiichi , Mizumachi Kunihiko , Ishimori Tatsujiro , Okuno Hisateru 
Published: July 2006

Abstract
The 15NO-complexes for trans-[PtCl(NH3)4(NO)]Cl2, trans-K2[PtCl(NO2)4(NO)] and M2[PtX5(NO)] (M=K and Cs, X=Cl and Br) were prepared. The effect of 15N-substitution on infrared spectra indicated that the weak absorption band at ca. 290 cm−1 is assigned to the Pt-(NO) stretching vibration and the absorptoin band in the region 530–570 cm−1 to the Pt-(NO) bending vibration.
Proton Magnetic Resonance Spectra of Metal Ammine Complexes. I. Cobalt(III) Pentammine Series
Authors: Yoneda Hayami , Nakashima Yoshiaki 
Published: July 2006

Abstract
The proton magnetic resonance spectra have been measured in dimethylsulfoxide on some cobalt(III) complexes of the type [CoX(NH3)5]. Ammine protons show two peaks, except in a complex with X=NO2−. The major peak, due to cis NH3, appears downfields and the minor one, due to trans NH3, upfields as compared with the shift in [Co(NH3)6]3+. In the case of X=CN−, the shift pattern is reversed. For [Co(NO2)(NH3)5]2+, the spectrum is a single peak. This chemical shift behavior is explained by a simple model based on Ramsay’s theory for chemical shift. It is concluded that the behavior arises primarily from paramagnetic anisotropy of the central cobalt (III) ion. The model used in this work is shown to be applicable also to the assignment of the PMR spectra for complexes of the types cis-[CoX2(NH3)4] and cis-[CoX2(en)2].
Implication of Diazonium Cations as Intermediates in the Photorearrangement of Azoxybenzenes
Authors: Bunce Nigel James 
Published: July 2006

Abstract
Photolysis of azoxybenzene and 2,2′-azoxytoluene in the presence of 2-naphthol gives, in addition to o-hydroxyazocompounds, 1-arylazo-2-naphthols, sometimes as the major products. This implies that cleavage into diazonium ions may sometimes be a major pathway in the irradiation of aromatic azoxycompounds. A mechanism is proposed to account for the formation of azonaphthols as well as the various side products that have previously been obtained from these reactions.
Estimation of the Structures and Electronic States of Radicals Using the INDO–SCF MO Method. I. Alkoxyl Radicals
Authors: Ohkubo Katsutoshi , Kitagawa Futoshi 
Published: July 2006

Abstract
The most energetically stable alkoxyl radicals take the following configuration: r(C–O)=1.36 Å, r(C–H)=1.12 Å, and ∠OCH=109°28′ for CH3O·, and r(C–O)=1.36 Å, r(C–C)=1.47 Å, and ∠OCC=108° for C2H5O·. The pseudo π orbital is observed in the C–O bond.
Benzo[h]quinolin-10-yl-N Iridium(III) Complexes
Authors: Nonoyama Matsuo 
Published: July 2006

Abstract
Benzo[h]quinoline(bhqH) is metallated with iridium(III) to give [Ir(bhq)2Cl]2 in which bhq is coordinated at 1-N and 10-C atoms. This complex reacts with a ligand(L) such as tri-n-butylphosphine and diethylsulfide to yield [Ir(bhq)2ClL].
The Reaction of Substituted Tropones with Diphenylketene
Authors: Asao Toyonobu , Morita Noboru , Iwagame Nobuo 
Published: July 2006

Abstract
The reaction of 2-methoxytropone and diphenylketene afforded (2+8)cycloadduct and 1-methoxy-8,8-diphenylheptafulvene which must be formed by the decarboxylation of the initially-formed (2+2)cycloadduct. 2-Dimethylaminotropone also gave the heptafulvene derivative. However, 2-chloro-, 2-cyano-, and 2,5-dimethoxytropone yielded only (2+8)cycloadducts.
The Reaction of Isocyanates with Carboxylic Acids and Thiocarboxylic Acids
Authors: Motoki Shinichi , Saito Takao , Kagami Hiroaki 
Published: July 2006

Abstract
Thiocarboxylic acids reacted with isocyanates or acyl isocyanates to give the stable addition products. However, similar products obtained from benzoic acid and acyl isocyanates dissociated into their components in solution.
Association Involving Optically Active Ions. III. Pfeiffer Effect in Tris(phenanthroline)-zinc(II) or –nickel(II) –Alkaloid Systems
Authors: Ogino Kazuko , Kumagai Tokue 
Published: July 2006

Abstract
Pfeiffer effect was studied in aqueous solutions containing tris(phenanthroline)metal(II) (metal=zinc or nickel) complexes and various alkaloids. The results were interpreted quantitatively from the viewpoint of stereoselective association and the resulting equilibrium shift. The contribution of π-π interaction between the complex and the alkaloid conjugate systems to the stereoselective association is suggested. NMR data were found to be consistent with the π-π interaction. Relation between the sign of the Pfeiffer rotation and the absolute configuration of the complex is presumed.
2,3,5,6-Tetra-aryl-1,2,4,5-tetra-azapentalenes. A New Heteroaromatic System
Authors: Matsumoto Akira , Lee Joung Hee , Yoshida Masayuki , Simamura Osamu 
Published: July 2006

Abstract
2,3,5,6-Tetra-aryl-1,2,4,5-tetra-azapentalenes (II) have been prepared by the dimerization of arylazoethynylarenes (I). The properties of the new ring system are discussed on the basis of their reactivities.
Mechanistic Studies on the Photooxidation of Chlorpromazine in Water and Ethanol
Authors: Iwaoka Teiki , Kondo Michio 
Published: July 2006

Abstract
It has been established that chlorpromazine undergoes photooxidation via its cation radical, yielding chlorpromazine 5-sulfoxide as an ultimate photoproduct. Molecular oxygen has been found indispensable not only for the formation of chlorpromazine cation radical but also for the formation of the sulfoxide from the radical. Oxygen atom in the sulfoxide originates from the atmospheric oxygen and not from water, which was ascertained by both tracer experiment and kinetic analysis. It was concluded that phenazathionium ion is not involved in the reaction. The possibility of singlet oxygen participation in the photooxidation was also ruled out. An intermediate, which is formed from the cation radical, was found as a precursor of the sulfoxide and was tentatively assigned as a peroxyl type radical.
Reaction of Ethyl α,α-Dichloroacetoacetate with Aldehydes
Authors: Takeda Akira , Tsuboi Sadao , Nakashima Isao 
Published: July 2006

Abstract
Ethyl α,α-dichloroacetoacetate reacted with aldehydes in the presence of sodium ethoxide to give α-chloropyruvate and/or α-chloroglycidate. 2,5-Bis(1′-chloroalkylidene)-1,4-cyclohcxanedione (4) was obtained as a by-product in a low yield.
The Cyclic Trimerization of Isocyanates by Organic Tin(II) Compounds Containing Sn–O–C Bonds
Authors: Wakeshima Ikuko , Suzuki Hiroshi , Kijima Ichiro 
Published: July 2006

Abstract
Organic tin(II) compounds containing Sn–O–C bonds were found to be effective catalysts for the cyclic trimerization of phenyl and ethyl isocyanate. The cyclic trimerization mechanism is discussed.
Selenium Catalyzed Synthesis of of Carbonates. The Reaction of Alkoxide with Carbon Monoxide and Oxygen in the Presence of Selenium
Authors: Kondo Kiyoshi , Sonoda Noboru , Sakurai Hiroshi 
Published: July 2006

Abstract
A novel selenium catalyzed synthetic reaction of carbonates was investigated. The reaction of alkoxides with carbon monoxide in the presence of stoichiometric amount of selenium gave carbonates in high yields under atmospheric pressure at 20°C in THF. When the resultant reaction solution was made to react continuously with the mixture gas of carbon monoxide and oxygen, catalytic formation of carbonates was achieved. Isolation of Se-alkyl monoselenocarbonate from the reaction mixture by addition of alkyl halide indicated that carboalkoxy sodium selenide might be formed as an intermediate in the course of present reaction. In connection with these reactions, the reaction of carbonyl selenide with sodium alkoxide in alcohol was also studied.
On the Stable Molecular-shapes of CmHm−4 Cata-condensed Nonalternant Hydrocarbons
Authors: Toyota Azumao 
Published: July 2006

Abstract
The energetically most favorable molecular-symmetry groups and geometrical structures of CmHm−4 catacondensed nonalternant hydrocarbons were examined systematically on the basis of the symmetry rule and the semiempirical SCF MO method. The first excitation energies in the fully-symmetrical nuclear arrangements were found to decrease with increasing the number of carbon atoms, showing a tendency to converge to a certain limiting value, ca. 0.8 eV. Molecules larger than a certain critical size (m∼10) were predicted to suffer the second-order Jahn-Teller distortion, exhibiting a double-bond fixation in the peripheral carbon skeleton. Using the most stable geometrical structures obtained, the electronic spectra of these molecules were calculated. Furthermore, the predictions of the stable molecular-shapes in the lowest excited singlet states were briefly mentioned.
Metal Complexes Containing Six-membered Chelate Rings. IV. The Preparation and Structure of Dichlorocobalt(III) Complexes with Tetramines Derived from 2,4-Pentanediamine
Authors: Mizukami Fujio 
Published: July 2006

Abstract
The tetramine ligands, 4,6-dimethyl-3,7-diaza-1,9-nonanediamine (2,3″, 2-tet), 6,8-dimethyl-2,5,9,12-tetraazatridecane (N,N′-Me2-2,3″, 2-tet), and 4,9-dimethyl-5,8-diaza-2,11-dodecanediamine (3″,2,3″-tet), were prepared by using RR- and RS-2,4-pentanediamine as the starting material. Six kinds of trans-dichloro cobalt(III) complexes with these ligands were prepared and characterized. Among these complexes, three kinds of optically active complexes were obtained. The RR-2,4-pentanediamine and RS-2,4-pentanediamine parts in these complexes were considered to take a λ-skew-boat and a chair conformation respectively on the basis of molecular models, PMR, and the absorption and CD spectra.
Valence States of Arsenic and Antimony in Sea Water
Authors: Gohda Shiro 
Published: July 2006

Abstract
A simple and convenient chemical procedure for the determination of As(III), As(V), Sb(III) and Sb(V) by thermal neutron activation analysis is proposed and applied to the study of the valence state of As and Sb in sea water. Immediately after sampling, As(III) and Sb(III) were separated from As(V) and Sb(V) by extracting their diethyldithiocarbamates with chloroform, and then back-extracted into diluted nitric acid. As(V) and Sb(V) in the aqueous phase were collected by thionalide cocrystallization. They were then irradiated for 30 min at a neutron flux of 2×1013 n/(cm2·s), and treated in the same manner as described in the previous report. The As and Sb were determined by gamma-ray spectrometry. Sea water has been found to contain 1.56–2.45 μg As/l and 0.37–0.60 μg Sb/l. 80–97% of arsenic and 70–94% of antimony existed as the pentavelent species, only 5–20% as the trivalent species, and the remainder was probably included in suspended matter.
Analysis of a Magnesium-containing: β-Eucryptite Solid Solution by the Lattice Constant Method and Its Application
Authors: Iwatsuki Masaaki , Tsukada Norio , Fukasawa Tsutomu 
Published: July 2006

Abstract
An X-ray diffraction method has been developed for the determination of the composition of a magnesium-containing β-eucryptite solid solution which consists of a pseudo-ternary system, SiO2–Mg1⁄2AlO2–LiAlO2. Standard samples of the solid solution within the range of 60–75 mol% SiO2 and 0–15 mol% Mg1⁄2AlO2 were prepared from high-purity materials by the “glass-crystallization” technique. The diffraction angles of the (206) and (212) planes were measured from the center of gravity of the profile recorded on a chart by a counter diffractometer. After having been corrected for various systematic errors, both angles were used for the calculation of the lattice constants. It was found that Mg1⁄2AlO2 and LiAlO2 contributed similarly to a0, but in a different way to c0. The composition of the solid solution in a commercial glass-ceramic could be determined from the correlation between the composition and the lattice constants. The standard deviation of the determination from one measurement was about 0.2–0.4 mol%, and the time required for analysis was about 30 min.