bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic Study of Dilute Aqueous Solutions of Urea, Guanidine Hydrochloride and Dioxane
Authors: Arakawa Kiyoshi , Takenaka Nobuo , Sasaki Katsutaka 
Published: July 2006

Abstract
An ultrasonic study on dilute aqueous solutions of urea, guanidine hydrochloride and dioxane was made by means of a pulse method, with the intention of investigating the influence of these solutes upon the structure of water. Ultrasonic absorption coefficient was measured in the range of frequency from 15 to 45 Mc/sec, and ultrasonic velocity was measured at 5 Mc/sec. Temperature was varied from 10 to 40°C. In urea solutions, the magnitude of α⁄f2 (α=absorption coefficient, f= frequency) decreases first very slowly with concentration, then rapidly in the range from about 0.5 to 3m and at about 4–6m reaches a nearly constant value. In guanidine hydrochloride solutions a similar change in the relation α⁄f2 vs. concentration takes place with a smaller amount than in urea solution. This shows that guanidine hydrochloride has greater ability as a structure breaker in liquid water than urea. In the dioxane-water system, absorption increases with the concentration of dioxane. A nearly flat region in the absorption vs. concentration curve is found for a small concentration of dioxane.
This feature in the α⁄f2vs. concentration curve, which is found in the small concentration region, is ascribed to the “cooperative breaking effect” upon the “open-packed structure” in water.
The Reactivity of the Electron Donor-Accepter Complex—Catalysis by 1,3-Dimethylalloxazine in an Enzymatic Model Reaction
Authors: Iwasawa Yasuhiro , Soma Mitsuyuki , Onishi Takaharu , Tamaru Kenzi 
Published: July 2006

Abstract
The effect of electron donor-accepter(EDA)-complex formation upon the reactivity (or catalytic activity) of 1,3-dimethylalloxazine, a model compound of co-enzyme, FMN, was examined in the redox reaction between methylene blue and ascorbic acid. The 1,3-dimethylalloxazine exhibited a behavior similar to the enzyme, having an optimal pH for the redox reaction. The characteristic behavior of 1,3-dimethylalloxazine was demonstrated in the presence of both 1,3-dimethylalloxazine and pyrene; such behavior was not to be observed upon the addition of either of them. It was accordingly suggested that the EDA complex formation would play an important role in the enzymatic reactions in vivo. The influence of various aromatic hydrocarbons upon the enzyme-like catalysis was examined.
Formation Constants of Chromium(II) Complexes with (O,O)-, (O,N)- and (N,N)-Type Ligands and Comparison with Those of the Other First Transition Metal Complexes
Authors: Fukuda Yutaka , Kyuno Eishin , Tsuchiya Ryokichi 
Published: July 2006

Abstract
The formation constants of the bivalent chromium complexes with various chelating ligands were determined by the pH titration method at the ionic strength μ=0.1 and at 25°C. The values of the formation constants for (O,O)-type complexes were logk1=3.85±0.05 and logk2=2.96±0.05 for oxalate ion, logk1=3.92±0.05 and logk2=3.21±0.05 for malonate ion, and logk1=9.89±0.05 for sulfosalicylate ion: for (O,N)-type complexes we obtained logk1=7.72±0.05 and logk2=7.54±0.05 for glycine, logk1=9.05±0.05 for 8-hydroxyquinoline, and logk1=7.53±0.05 for β-alanine. Based on these values together with the corresponding values of the (N,N)-type complexes, the effect of the coordinating atoms and of the number of members in a chelate ring upon the stabilities was discussed. These values were compared with those for the other transition metal complexes.
Polarography of Iron(III)- and Europium(III)-Acetylacetonate Complexes in N,N-Dimethylformamide
Authors: Misumi Seizo , Aihara Makoto , Nonaka Yasuomi 
Published: July 2006

Abstract
The reduction potentials of Fe(acac)3 and Eu(acac)3 in DMF are shifted to more positive potentials by the addition of cations (Li+ and Mg2+) to the supporting electrolyte of tetraethylammonium perchlorate. Studies of the complexes show that the effect is caused by coordinative relaxation reaction of the Fe(acac)3− reduction product in which acetylacetonate ligand becomes transferred to the cation. However, in the case of Eu(acac)3−, acetylacetonate ligands seemed to be completely stripped off. Cyclic voltammetric data indicate reduction and reoxidation processes of the complexes.
Benzyl Bromide-Amine Reaction in Nitrobenzene-Ethanol Mixtures
Authors: Radhakrishnamurti P S , Panigrahi G P 
Published: July 2006

Abstract
The reactions between benzyl bromide and various bases as well as p-nitrobenzyl bromide and various bases have been studied in nitrobenzene-ethanol mixtures (80:20 v/v). The reaction is total second order as stated earlier. Comparison is made with the previous work on the same reaction with benzyl chloride and p-nitrobenzyl chloride.
Synthesis of Furonaphthoquinones
Authors: Kakisawa Hiroshi , Tateishi Mitsuru 
Published: July 2006

Abstract
The reaction of 2-acetoxy-1,4-naphthoquinone with N-(1-propenyl)morpholine in an ordinary atomsphere afforded 3-methylnaphtho[2,3-b]furan-4,9-quinone in a modest yield. When this reaction was carried out in an atmosphere of nitrogen, the reaction product was an aminodihydronaphthofuran XII, which was then converted into 3-methylnaphtho[1,2-b]-2,3-dihydrofuran-4,5-quinone by succesive treatments with ferric chloride, sodium borohydride, and sufuric acid.
The Reductive Coupling Reactions of Some Chloromethylbenzene Derivatives with Iron(II) and Copper(I) Complexes
Authors: Onuma Kazuhiko , Yamashita Junzo , Hashimoto Harukichi 
Published: July 2006

Abstract
The reductive coupling reactions of some chloromethylbenzene derivatives with ferrous and cuprous chloride in ethanol or in acetonitrile and the effect of some additives on this reaction have been investigated. Benzotrichloride has been reduced selectively to tolan tetrachloride with ferrous chloride, while with cuprous chloride-ethylenediamine (a stronger reductant than ferrous chloride) mixtures of tolan and tolan dichloride or tolan tetrachloride are obtained depending on the condition. Similarly benzal chloride, diphenylmethyl chloride and diphenyldichloromethane are also reduced to give coupling products. In case of ferrous chloride the addition of ethylenediamine or pyrophosphoric acid raises the yield considerably and in case of cuprous chloride selection of the ratio, organic halide: copper (I): ethylenediamine, makes it possible to control the product distribution. The reaction mechanism and the effect of the additives are discussed.
Intermediate Stages of the Nitration of Hexamethylbenzene to Dinitroprehnitene
Authors: Suzuki Hitomi 
Published: July 2006

Abstract
A syrupy substance formed in quantity during the nitration of hexamethylbenzene to dinitroprehnitene has been found to be a complex mixture of varying amounts, depending markedly on the conditions, of 2,3,4,5,6-pentamethylbenzyl nitrate, 5,6-bis(nitrooxymethyl)-1,2,3,4-tetramethylbenzene, nitropentamethylbenzene, 6-nitro-2,3,4,5-tetramethylbenzyl nitrate, 2,3,4,5,6-pentamethylphenylnitromethane, bis (2,3,4,5,6-pentamethylbenzyl) ether, pentamethylbenzaldehyde, and several other unidentified carbonyl compounds, nitrite esters, and aliphatic nitro compounds. On the basis of the products isolated, a possible path by which hexamethylbenzene can be converted into dinitroprehnitene has been suggested.
The Total Synthesis of Dehexyl-deisovaleryloxy-antimycin A1
Authors: Kinoshita Mitsuhiro , Umezawa Sumio 
Published: July 2006

Abstract
A biologically active prototype of antimycin A series has been synthesized. The dilactone moiety was synthesized from a masked l-threonine and γ-hydroxyvalerate and condensed with an O-masked derivative of 3-nitrosalicylic acid N-hydroxysuccinimide ester. Hydrogenation followed by formylation afforded the anti-fungal substance. This synthesis established a possible general synthetic pathway to the members of antimycin A.
The Catalytic Oxidation of Carbon Monoxide on Titanium Dioxide; Anatase and Rutile
Authors: Onishi Yoshito , Hamamura Takuya 
Published: July 2006

Abstract
For the purpose of investigating the correlation between the crystal structure of titanium dioxide and its catalytic activity, the catalytic oxidation rate of carbon monoxide and the desorption rate of oxygen from the sample surface have been measured on anatase, rutile, and an anatase-rutile mixture. The oxidation of carbon monoxide was investigated by a static method at temperatures of 250–550°C and under gas pressures of 10−2–150 mmHg. The desorption of oxygen was carried out at 600–750°C. The reaction rate was proportional to PCO and did not depend on either PCO2 or PCO2 The activation energy was 16.0 kcal/mol for anatase and 6.7 kcal/mol for rutile. The catalytic activity per unit of the surface area of rutile was 3—6 times as much as that of anatase. The reaction rate almost coincided with the rate of the reduction of titanium dioxide by carbon monoxide. The electric resistance of the sample was little affected by the PO2. The following reaction mechanism is proposed to explain the results. The rate-determining step is the reaction between the surface oxygen of the sample and the carbon monoxide physisorbed or that which has just collided with the surface coming from the gas phase; the oxygen vacancy thus formed on the surface is quickly filled with oxygen of the gas phase. The difference in the activation energy of the catalytic action between the two structures is based upon the difference in the activation energy of the oxygen desorption from the surface structure; the activation energies are 57.8 kcal/mol for anatase and 38.4 kcal/mol for rutile.
Formation of Hypophosphate in the Radiolysis of Phosphite Solution
Authors: Matsuura Niro , Yoshimura Masahito , Takizawa Masao , Sakaki Yukio 
Published: July 2006

Abstract
The formation of hypophosphate and phosphate in the radiolysis of a phosphite solution was established by the anion-exchange chromatographic technique. The quantitative determination of their yields was made by colorimetry of the phosphate and hypophosphate with the Mo(V)+Mo(VI) reagent, which develops molybdenum-blue colors in two steps at different temperatures. The G values in an aerated condition are 0.01 molecules/100 eV in acid and 0.1 molecule/100 eV in neutral pH with respect to the hypophosphate formation, independent of the phosphite concentration. In a deaerated system much higher values are obtained, amounting to around 0.5 molecules/100 eV at a phosphite concentration of 10−3 m. The G values of hypophosphate plus phosphate are around 3.0; this is in agreement with the half-value of the primary radical yields, 1/2·(gred+gOH), reported in the data derived from the radiation-chemical studies in the aqueous system. The hypothesis that the hypophosphate (IV) ion radical is a transient species in the oxidation of phosphite to phosphate is supported by the results obtained in this work.
The Solvent Effect on the Reaction of 1,1,4,4-Tetraphenyl-2-halobuta-2,3-dien-1-ol with Mercuric Halide
Authors: Toda Fumio , Ooi Nobuhiro , Akagi Katsuhiko 
Published: July 2006

Abstract
The reaction of the title compound (I) with mercuric halide in an aprotic and in a protic solvent afforded the fulvene derivative (VII) and the dihydrofuran derivative (VIII or IX) respectively. Both the cross-reactions (bromo-analog of I (Ia)+HgCl2, chloro-analog of I (Ib)+HgBr2) in an aprotic solvent afforded the chloro-fulvene derivative (VIIb). However, when the above reactions were carried out in a protic solvent, the product was the dihydrofuran derivative (IX), in which the halogen combining with carbon is chlorine and that combining with mercury is bromine. On the basis of the results of those cross-reactions, the reaction mechanism will be discussed. Acetonitrile showed distinctive behavior. In acetonitrile, the bromine of Ia was easily exchanged with the chlorine of sodium chloride at room temperature, and Ib was obtained quantitatively.
Sterically Controlled Syntheses of Optically Active Organic Compounds. XIII. Catalytic Hydrogenation of Symmetric Substrates in the Presence of Asymmetric Molecules
Authors: Yoshida Takao , Harada Kaoru 
Published: July 2006

Abstract
Several organic acids which contain C=O, C=N, and C=C double bonds are catalytically hydrogenated in the presence of various optically active organic bases by the use of several solvent systems. Effects of bases and solvents on the optical activities of the products are examined.
Syntheses and Reactions of Functional Polymers. LIV. Syntheses and Polymerizations of O-Substituted-N-hydroxymaleimides
Authors: Narita Mitsuaki , Teramoto Takero , Okawara Makoto 
Published: July 2006

Abstract
The reverse Diels-Alder reaction of N-substituted maleimide adducts of furan is a useful method for the preparation of N-substituted maleimides which can not be obtained by the direct dehydration of maleamic acids owing to the formation of the corresponding isomaleimides. O-Benzyl, O-acetyl, O-benzoyl, O-benzenesulfonyl, and O-methyl-N-hydroxymaleimide adducts of furan decompose at 140–190°C to produce the corresponding maleimides. The homo- and co-polymerization with styrene of these maleimides were carried out and monomer reactivity ratios and Q-e values for these maleimides were determined. The copolymer obtained were converted to the copolymer of N-hydroxymaleimide and styrene.
The Stereochemistry of Nucleophilic Addition. I. The Reformatsky Reaction of 2-Methyl- and 2-Ethylcyclohexanones
Authors: Matsumoto Takashi , Fukui Kenji 
Published: July 2006

Abstract
The Reformatsky reaction of 2-methyl- or 2-ethylcyclohexanone with ethyl bromoacetate gave a mixture of epimeric alcohols, which were then separated by column chromatography in an 80 : 20 ratio. The configurations of these major and minor products were identified as ethyl trans- and ethyl cis-2-methyl (or ethyl)-1-hydroxycyclohexylacetate respectively on the basis of their IR analyses, their chromatographic behavior, and correlation with the products of the Grignard reaction, the stereochemistry of which is well known. The NMR spectra of these epimeric alcohols are also discussed, and it is suggested that the chemical shifts of the methylene protons alpha to the ethoxycarbonyl group and of the proton of the hydroxyl group gives useful data for their stereochemical assignments. From these results, it is evident that the Reformatsky and the Grignard reactions proceed in a similar fashion; that is, the entering group predominantly approaches to the carbonyl group from the equatorial side. The stereoselectivity of the Reformatsky reaction is slightly less than that of the Grignard reaction.
Peptide Synthesis by Oxidation-Reduction Condensation. I. Use of NPS-Peptides as Amino Component
Authors: Ueki Masaaki , Maruyama Hiroshi , Mukaiyama Teruaki 
Published: July 2006

Abstract
Sulfenamides were found to react readily with soft nucleophiles in the presence of active hydrogen compounds. A new method for the synthesis of carboxamide from metal carboxylate, sulfenamide and tertiary phosphine was developed. The effects of metal component were examined. Copper(II) salts gave the best result. In a similar way, peptides were synthesized by the reaction of copper(II) salts of acylamino acid, or free acylamino acid in the presence of cupric chloride and triethylamine, with NPS-amino acid derivatives and triphenylphosphine. When organo-mercuric compounds such as dianisylmercury were used in place of cupric chloride and triethylamine in the above reaction, almost complete retention of configuration was observed by the Young test.
Extraction and Spectrophotometric Determination of Copper(II) with 2-Thenoyltrifluoroacetone
Authors: Akaiwa Hideo , Kawamoto Hiroshi , Abe Masanobu 
Published: July 2006

Abstract
A highly sensitive method for the spectrophotometric determination of copper(II) with 2-thenoyltrifluoroacetone (TTA) is described. Copper(II) is extracted with TTA in cyclohexane at pH 5.5 and the residual TTA in the organic phase is removed by washing with sodium hydroxide solution containing pyridine. Pyridine is added to the washing solution so that it forms an adduct and prevents the copper-TTA chelate from decomposing during the alkali treatment process. The absorbance of the organic phase is measured at 340 mμ. Beer’s law is followed over the concentration range of 0.1 to 1.0 μg of Cu per ml, the sensitivity being 0.0023 μg Cu/cm2 at 340 mμ. The present method was applied to the analysis of natural water.
The Nature of a Bond between a Water Molecule and a Protonated Propylene in the Activated Complex for the Acid-catalyzed Hydration of Propylene
Authors: Takaya Haruo , Todo Naoyuki , Hosoya Tadasuke , Minegishi Toshio 
Published: July 2006

Abstract
The nature of a bond between a water molecule and a protonated propylene in the activated complex for the acid-catalyzed hydration of propylene was discussed. The number of water molecules contained in the activated complex, 1.3, was obtained by applying the acidity function, T0, to the dependency of the logk1 on the acid concentration for the hydration of various olefins. The general relationship between the electrostriction and the hydration number of various uni-valent cations was also discussed, and these ions were divided into two separate groups. In the first group, the hydration was caused by electrostatic interaction, while in the second group, the hydration was caused mainly by covalent bond formation. Since the representative point of the hydration of propylene was located near the first group, it was concluded that a molecule of water is held in the activated complex by electrostatic interaction. On the basis of these considerations, the present authors propose a hypothesis which is useful in characterizing the nature of a bond between a water molecule and a protonated substrate in an activated state: (a) If the logk1 for a reaction increases linearly with –H0, a water molecule (or molecules) is held in an activated complex by electrostatic interaction. (b) If the logk1 for a reaction increases linearly with the logma, a water molecule is held in an activated complex by the formation of a covalent bond. k1: the first order rate constant; H0: Hammett’s acidity function; ma: acid concentration.
Analysis of Skeletal Deformation Vibration Spectra in Relation to the Molecular Structure
Authors: Fujiyama Tsunetake 
Published: July 2006

Abstract
Deformation vibrations associated with displacements of skeletal heavy atoms are mainly discussed. It is shown that skeletal deformation vibrations are sensitive to the change of an azimuthal angle θ and that the frequencies of the vibrations are specific for the structure of rotational isomers. The θ-dependency of skeletal deformation vibrations corresponds exactly to that of elements of a kinetic energy matrix \barG. The results emphasize the simplicity and the usefulness of the approximate normal coordinate treatment in which only skeletal heavy atoms are taken into account.
Liquid-phase Adsorption from Binary Solutions on Silica Gel. Separation Factors and Orientation of Adsorbed Components on the Surface
Authors: Kagiya Tsutomu , Sumida Yūzō , Tachi Toshihiro 
Published: July 2006

Abstract
The preferential adsorption equilibria of various binary solutions of cyclohexane-aromatic compounds and cyclohexane-cyclic ethers on chromatographic silica gel have been studied at 30°C. On the basis of the assumption that the adsorption is of the Langmuir-type, the separation factors (α) and the numbers of moles in the adsorbed-phase per unit mass of silica gel (nσ⁄m) have been calculated. The values of logα correlate well not only with the electron-donating properties of the preferentially-adsorbed components, but also with the powers of the gas-phase adsorption on silica gel and of the liquid-liquid interaction with liquid trimethylsilanol. Moreover, on the basis of the information on nσ⁄m, the orientation angles of the adsorbed components on the surface have been evaluated. The adsorption of the aromatic hydrocarbons was nearly flat to the surface, and that of the cyclic ethers, perpendicular.
The Codimerizations of Styrene with Vinyl Compounds Catalyzed by Olefin-palladium(II) Chloride Complexes
Authors: Kawamoto Keiji , Tatani Atsushi , Imanaka Toshinobu , Teranishi Shiichiro 
Published: July 2006

Abstract
The codimerization of styrene with vinyl compounds catalyzed by di-μ-chloro-dichlorobis(styrene)dipalladium(II), (Pd(C6H5CH=CH2)Cl2)2, was investigated in a homogeneous system under mild conditions. The reaction of styrene and methyl acrylate carried out at 50°C for 6 hr yielded 220% codimers, 169% dimers of methyl acrylate, and 18% dimers of styrene, on the basis of the palladium(II) used. The codimerizations of styrene with vinyl acetate and with methyl vinyl ketone gave 50% codimer and 125% codimers respectively. When nitroethylene and n-butyl vinyl ether were used as the vinyl compound, no codimers were formed. The codimerization of styrene-d3 with ethylene was also carried out. The reaction mechanism involving the five-coordinate hydridopalladiumolefin intermediate was proposed and discussed in the terms of the distribution of deuterium in the codimer of styrene-d3 and ethylene, the functional group effects of vinyl compounds, and solvent effects on the codimerization.
The Crystal and Molecular Structure of 2,5-Distyrylpyrazine
Authors: Sasada Yoshio , Shimanouchi Hirotaka , Nakanishi Hachiro , Hasegawa Masaki 
Published: July 2006

Abstract
2,5-Distyrylpyrazine(C20H16N2), which has photo-polymerizability in the crystalline state, crystallizes in the orthorhombic system with cell dimensions of a=20.638, b=9.599, and c=7.655 Å, including four molecules in the unit cell. The space group is Pbca. The structure has been determined by the direct method and refined by the block-diagonal-matrix least-squares method using three-dimensional data. The molecules is not planar; the average plane of the pyrazine ring makes a dihedral angle of 12.09° with that of the benzene ring. The molecules are spaced by the c-translation forming an almost parallel plane-to-plane stack. In this stack, the ethylenic double bonds approach each other at the shortest intermolecular distances of 3.939 Å, since the long axis of the molecule makes an angle of about 30° with the c-axis. Therefore, the polymerization may occur between these double bonds to form a cyclobutane ring.
The Thermal Isomerization of Pinane and Its Products
Authors: Tanaka Juntaro , Katagiri Takao , Ozawa Kiyomi 
Published: July 2006

Abstract
The stereochemistry of the reduced products of the iridenes was studied, and the main product produced by the thermal isomerization from pinane was confirmed to be 1-trans-2-dimethyl-trans-3-isopropenylcyclopentane, unlike as in the literatures. Moreover, the ozonolyses of the iridenes were reexamined in detail, and the following results were obtained: 1) When the ozonides were decomposed with Na2CO3-H2O2, the substituent on C-3 was epimerized. 2) On the other hand, when the ozonides were treated with Zn-CH3COOH, no such epimerization occurred. Consequently, it was found that the former method when used for the confirmation of iridenes, did not give good results for assignments of these compounds.
The Chemistry of Protactinium. IX. A Study of the Solvent Extraction of Protactinium(V) from a Perchloric Acid Solution Using Di(2-ethylhexyl)phosphoric Acid as the Extractant
Authors: Mitsugashira Toshiaki 
Published: July 2006

Abstract
Studies of the chemical behavior of protactinium(V) in a perchloric acid solution were carried out by the HDEHP-benzene extraction method. When the protactinium concentration was lower than 10−7 m, the extraction reaction was considered to proceed as:
PaO(OH)2+aq.+ 3(HA)2 org.= PaOp(OH)qA5−2p−q(HA)2p+q+1 org.+ 2H+aq.+ (2–p–q)H2Oaq.
where p=1, q=0 or 1, and p=2, q=0
and
Pa(OH)32+aq.+ 3(HA)2 org.= PaOp(OH)qA5−2p−q(HA)2p+q+1 org.+ 2H+aq.+ (3–p-q)H2Oaq.
where p=0, q=0, 1, 2, or 3; p=1, q=0 or 1 and p=2, q=0.