bluuebunny/crossref_metadata_2025_split huggingface dataset:
Circular Dichroism of Copper(II) Complexes with Optically Active Tetradentate Ligands in Aqueous Solutions
Authors: Murakami Tasuku , Hatano Masahiro 
Published: July 2006

Abstract
The circular dichroism (CD) spectra of copper(II) complexes containing the asymmetric tetradentate ligands, such as ethylenediamine-N,N′-di-l-α-propionate, ethylenediamine-N,N′-di-l-α-isovalerate, and ethylenediamine-N,N′-di-l-α-hydrocinnamate, were measured in an aqueous solution. Each of the CD curves can be resolved into four components in the d–d region by Gaussian analysis; these components are related to the four possible d–d transitions of the copper(II) ion. The visible CD spectrum profile of the complexes varies with the variation in ligands; this implies that the conformation of the complexes is affected appreciably by the bulkiness of the side chain in the ligand.
Application of the Zone Melting Technique to Metal Chelate Systems. VII. Computer-assisted Consideration on the Solute Distribution Profiles in Zone Melting Process
Authors: Maeda Shigeru , Kobayashi Hiroshi , Ueno Keihei 
Published: July 2006

Abstract
A new equation is derived which gives the solute distribution along a column after a zone melting chromatography (ZMG) process, where the initial charge of a sample mixture of k&lt;1 is placed on the upper end of the column, one zone length high. The solute distribution differs significantly from that obtained by Pfann’s equation on an infinite ingot, in the neighborhood of the upper end as expected from the difference in the initial conditions. The solute distribution is calculated numerically for the case in which the initial charge is placed by several zone lengths on the column top. The present multiple zone charge method shows little difference in solute distribution from the conventional single zone charge method, having the advantage of increasing the sample amount to be fractionated. Numerical calculation is performed to find the zone length with which the greatest amount of the solute of k&lt;1 is concentrated into the bottom fraction of a certain length of a given column after each zone pass. A series of resulting zone lengths, showing a stepwise shortening, pass after pass, provides the optimum mode of decrease in the zone length.
The Tautomeric Equilibria of 4-(Dialkylamino)azobenzene Derivatives. II. 2- and/or 2′-Methyl-4-(dimethylamino)azobenzene Derivatives
Authors: Yamamoto Shunzo 
Published: July 2006

Abstract
The tautomeric equilibrium constants, Kt=[ammonium ion]/[azonium ion], of the first conjugate acids of 2- and/or 2′-methyl-4-dimethylaminoazobenzene derivatives were estimated by the spectrophotometric method. The effects of the 2- and 2′-methyl groups on the basicity of the amino and the azo nitrogens were examined in order to explain the effects on the tautomeric equilibrium. The effects of the 2- and 2′-methyl groups on the basicity of the amino nitrogen is an inductive one only, while the effects on the basicity of the azo nitrogens are both electronic and steric. The latter effect of the 2′-methyl group is very large, but that of the 2-methyl group is not significant. The order of Kt in a series of compounds is almost the same as that of the basicity of the azo nitrogens. That is to say, the magnitude of Kt is mainly governed by the basicity of the azo nitrogens.
Carbon Products Prepared from Variant Pitch Materials. VIII. The Preparation of Isotropic Pitch Carbon with a High Density
Authors: Otani Sugio , Oya Asao 
Published: July 2006

Abstract
The present works were undertaken in order to prepare the isotropic Pitch Carbon with a high density and with a desired degree of graphitization. The tablets were prepared by pressing some kinds of variant pitch materials and were then heat-treated below 2600°C in N2 gas. Isotropic Pitch Carbon with a high density and with a low degree of graphitization can be readily prepared by pressing the non-graphitizable variant pitch material under high pressure. On the other hand, for the purpose of preparating isotropic Pitch Carbon with a high density and with a high degree of graphitization, a graphitizable variant pitch material with a low softening point, —in other words, with a good ability of sintering— was pressed into tablets under low pressure. The typical properties of the Pitch Carbon thus obtained (H.T.T. 2600°C) were as follows: Bacon Anisotropic Factor: 1.01; Bulk density: 1.79 g/cc; d002: 3.40 Å; Lc: 210 Å.
The Reaction of Nucleophilic Reagents at the β-Position of 3-Bromo-4-nitropyridine N-Oxide
Authors: Matsumura Eizo , Ariga Masahiro 
Published: July 2006

Abstract
Some nucleophilic substitutions on the β-position of the pyridine nucleus were carried out. The reactions of 3-bromo-4-nitropyridine N-oxide(1) with diethyl sodiomalonate, ethyl sodiocyanoacetate, and ethyl sodioacetoacetate in diethyl carbonate or pyridine afforded 3-bis-(ethoxycarbonyl)methyl-4-nitropyridine N-oxide (2), 3-cyano(ethoxycarbonyl)methyl-4-nitropyridine N-oxide (3), and 3-acetyl(ethoxycarbonyl)methyl-4-nitropyridine N-oxide (4) respectively, and ethyl sodioacetoacetate, when treated at a higher temperature, gave 3-ethoxycarbonyl-2-methyl-furo(3,2-c)pyridine N-oxide (5). A probable mechanism of the reaction was presented.
Kinetics of Multidentate Ligand Substitution Reactions. XV. Substitution Reactions of 1,2-Cyclohexanediamine-N,N,N′,N′-tetraacetic Acid (CyDTA) with Zinc(II) Iminodiacetate (IDA), N-(2-Hydroxyethyl)iminodiacetate (HIDA), and Nitrilotriacetate (NTA) Complexes and Those with Cobalt(II)-IDA, -HIDA, NTA, -N-(2-Hydroxyethyl)ethylenediamine (EtEN), and Diethylenetriamine (Dien) Complexes
Authors: Kodama Mutsuo , Hagiya Kaoru 
Published: July 2006

Abstract
The kinetics of the substitution reactions of CyDTA with zinc(II)-IDA, -HIDA, and -NTA complexes and those with cobalt(II)-IDA, -HIDA, -NTA, -EtEN, and Dien complexes were studied by using the polarographic technique. All the substitution reactions studied in this paper were found to have a common reaction mechanism. They were first-order with respect to the CyDTA anion, and they were also first-order with respect to the metal(II) complex with a 1 : 1 composition; their reaction mechanism could be formulated as:
(Remark: Graphics omitted.)
From a comparison of the observed rate constants with those estimated on the basis of the proposed reaction intermediate, the detailed reaction mechanism and structures of the reaction intermediates were discussed. The steric effect of the cyclohexane ring on the rate of the substitution reaction was also discussed.
The Synthesis of Azulene Derivatives Condensed with Several Heterocycles
Authors: Nozoe Tetsuo , Asao Toyonobu , Kobayashi Masao 
Published: July 2006

Abstract
The reactions of ethyl 1,2-diaminoazulene-3-carboxylate with formic acid, nitrous acid, glyoxal sodium bisulfite, diacetyl, and benzil afforded the corresponding azulene derivatives condensed at the 1,2-position with nitrogen-containing heterocycles, namely, imidazole, triazole, and pyrazine rings. 2-Amino-1-formylazulene reacted with guanidine or thiourea to give 2-aminoazuleno[2,1-d]pyrimidine. The ultraviolet and visible absorption spectra of these azulenes are presented.
Synthesis of “Reversed” Nucleosides of Some Purine and Pyrimidine Bases
Authors: Fukatsu Shunzo , Takeda Yoshiro , Umezawa Sumio 
Published: July 2006

Abstract
The title compounds have been synthesized by condensation of terminal iodo-sugars with purine bases and pyrimidine bases in dime thy lformamide in the presence of sodium hydride or lithiu a hydride.
Formation and Reaction of Cyclohexanone Oxime Hydrogen Sulfate
Authors: Fukui Kiyoshi , Uchida Masaru , Masaki Mitsuo 
Published: July 2006

Abstract
Cyclohexanone oxime hydrogen sulfate, prepared by the reaction of cyclohexanone oxime with sulfur trioxide–1,4-dioxane complex under mild conditions, was isolated as stable salts with various Lewis bases. It was found that a Beckmann rearrangement of the oxime hydrogen sulfate to 3,4,5,6-tetrahydro-2H-azepin-7-ol hydrogen sulfate was retarded by the weak Lewis base 1,4-dioxane and prevented by a stronger Lewis base aniline. The rearrangement of the oxime hydrogen sulfate was also found to be promoted by Lewis acids such as sulfur trioxide, tin tetrachloride or zinc chloride. Hydrogen chloride retarded the rearrangement. Alcoholysis of the oxime hydrogen sulfate gave cyclohexanone oxime and monoalkyl sulfate quantitatively, while hydrolysis of the oxime hydrogen sulfate gave cyclohexanone, cyclohexanone oxime and ε-caprolactam.
Reaction of 3,4,5,6,-Tetrahydro-2H-azepin-7-ol Hydrogen Sulfate with Cyclohexanone Oxime–Tin Tetrachloride Complex
Authors: Masaki Mitsuo , Fukui Kiyoshi , Uchida Masaru , Yamamoto Koichi , Uchida Izuhiko 
Published: July 2006

Abstract
Cyclohexanone oxime hydrogen sulfate was found to undergo facile rearrangement to 3,4,5,6-tetrahydro-2H-azepin-7-ol hydrogen sulfate in the presence of ε-caprolactam–tin tetrachloride complex, while the oxime hydrogen sulfate decomposed in the presence of ε-caprolactam. Other metal halides were studied to see if the oxime hydrogen sulfate undergoes rearrangement in the presence of the lactam. Gyclohexanone oxime–tin tetrachloride complex was synthesized. Its reaction with the tetrahydroazepin-7-ol hydrogen sulfate was found to give the lactam–tin tetrachloride complex and the oxime hydrogen sulfate which regenerated the tetrahydro-azepin-7-ol hydrogen sulfate in the reaction system. Tin tetrachloride complex was prepared with several oximes.
Synthetic Studies of Bacitracin. VIII. Synthesis of Cyclohexapeptide Moiety
Authors: Munekata Eisuke , Masui Yoshihiro , Shiba Tetsuo , Kaneko Takeo 
Published: July 2006

Abstract
For the purpose of synthesis of antibiotic bacitracin of six amino acids-membered ring formula, the following intermediate peptides, i.e., cyclo-(Nα-benzy]oxycarbonyl-l-lysyl-Nδ-cyclopentyloxycarbonyl-d-ornithyl-l-isojeucyl-d-phenylalanyl-l-histidyl-α-methyl-l-aspartyl) (III) and Nα-benzyloxycarbonyl-Nε-t-butyloxycarbonyl-l-lysyl-Nδ-cyclopentyloxycarbonyl-d-ornithyl-l-isoleucyl-d-phenylalanyl-Nim-benzyl-l-histidyl-l-aspartyl-d-isoasparagine benzyl ester (IV) were prepared. In this synthesis, cyclopentyloxycarbonyl group was introduced to protect δ-amino group of ornithine residue and cleavability of this protecting group for hydrogen fluoride was investigated.
Kinetic Studies on the Cationic Ring-Opening Polymerization of Tetrahydrofuran Initiated by Superacid Esters
Authors: Kobayashi Shiro , Danda Hidenori , Saegusa Takeo 
Published: July 2006

Abstract
The present paper descibes kinetic studies on the cationic ring-opening polymerization of tetrahydrofuran (THF) initiated by superacid esters such as ethyl fluorosulfate (EtOSO2F), chlorosulfate (EtOSO2Cl), and trifluoromethanesulfonate (EtOSO2CF3). The phenoxyl end-capping method was found to de applicable to kinetic analyses of the THF polymerization initiated by superacid esters. Also, the rate constants of propagation (kp) and of initiation (ki) were determined directly by NMR spectroscopic method. Rate constants determined by these two methods were in good agreement within experimental error. As a polymerization mechanism it was established that the propagation proceeds via cyclic oxonium species. The kp values of superacid esters varied depending upon the nature of the counter anion, OSO2X−, e.g., kp at 0°C in CH2Cl2: 0.66×10−3 (X=F), 1.4×10−3 (X=Cl), and 1.7×10−3 (X=CF3) 1/mol·sec, respectively. These magnitudes, however, were at least lower than one half of those of typical Lewis acid initiators. Initiation by superacid ester is a dipole-diple reaction, and ki values were about 1/10–1/20 of the corresponding value of triethyloxonium tetrafluoroborate (Et3O+BF4−). Activation parameters were calculated for both the propagation and initiation reactions. In order to compare the present systems with those of superacid initiators, model reactions were examined by NMR spectroscopy.
Kinetic Study on the Ring-Opening Polymerization of Tetrahydrofuran by Pyrosulfuryl Chloride Initiator
Authors: Kobayashi Shiro , Saegusa Takeo , Tanaka Yoshiaki 
Published: July 2006

Abstract
This paper deals with a kinetic study of the ring-opening polymerization of tetrahydrofuran (THF) initiated by pyrosulfuryl chloride (PSC). The kinetic analysis was based on the determination of the concentration of propagating species, [P*], by the phenoxyl end-capping method. The rate constants of the three elementary processes, propagation (kp), initiation (ki), and termination (kt), were determined. Activation parameters for the propagation were; ΔEp\eweq=12 kcal/mol, and Ap=7.6×106 l/mol·sec. From the kp values and the NMR study of the THF–PSC reaction, it is concluded that the propagation proceeds via the bis-oxonium species 5b. The ester type species 5a may be involved at a very early stage of polymerization. However, its contribution was quite small throughout the polymerization. The THF polymerization initiated by PSC was characterized by the fast initiation. The mechanism of termination was also examined. The THF polymerization by trifluoromethanesulfonic anhydride was also studied kinetically, which was characterized by a living propagation by bis-oxonium species.
The Metalation of Fluorene by Means of the Diethylmagnesium–Hexamethylphosphoramide System
Authors: Tomoi Masao , Kakiuchi Hiroshi 
Published: July 2006

Abstract
The metalation of fluorene by means of the Et2Mg–HMPA system was investigated. The reaction scarcely occurred at all when the mole ratio of HMPA: Et2Mg fell below 1:1, but it proceeded easily when the ratio was over 1:1, and a solvent-separated ion pair of magnesium fluorenide was formed. When the ratio was 2:1, the order of reaction was unity in both fluorene and Et2Mg. It was demonstrated by the kinetic and NMR studies that the active species of metalation in such a case was not Et2Mg but the Et2Mg–HMPA complex, in which two molecules of HMPA are coordinated to Et2Mg.
Reactions of the Iodocarbenoid of Zinc. I. The Synthesis of Alkyl-substituted 7-Ethylcyclohepta-1,3,5-trienes via the Ring-expansion of Alkylbenzenes with Diethylzinc and Iodoform
Authors: Miyano Sotaro , Hashimoto Harukichi 
Published: July 2006

Abstract
By treatment with diethylzinc and iodoform, benzene gave 7-ethylcyclohepta-1,3,5-triene in a yield of 58%, along with a quantitative formation of ethyl iodide. Alkylbenzenes, including methyl-, ethyl-, isopropyl-, tert-butyl-, and o-dimethylbenzene, gave the corresponding alkyl-substituted 7-ethylcyclohepta-1,3,5-trienes in yields of 60, 45, 41, 35, and 52% respectively. The tropylium iodide resulting from the adduct of the iodocarbenoid of zinc to benzene (7-iodonorcaradiene) is suggested as an intermediate in the formation of the 7-ethylcycloheptatriene.
The Preparation and Reactions of N-Substituted Hexafluoroisopropylideneimines
Authors: Ishikawa Nobuo , Kitazume Tomoya 
Published: July 2006

Abstract
N-Aryl- and N-alkylhexafluoroisopropylideneimines (2) were prepared from the hexafluorothioacetone dimer (1) by treatment with either aryl- or alkylamines. These imines reacted with alcohols and thiols to give three addition products, 7, 8, and 9. Phenylhydrazone (3), semicarbazone (4), hydrazone (5), and azine (6) of hexafluoroacetone were also obtained directly from 1 and the corresponding carbonyl reagents.
The Effect of Acylamino Groups in Diazo-coupling Reactions
Authors: Hashida Yoji , Mitsumura Kazuo , Sekiguchi Shizen , Matsui Kohji 
Published: July 2006

Abstract
A kinetic study has been made of the coupling reactions of diazonium salts with N,N-dialkyl-N′-acyl-m-phenylenediamines, including N′-acetyl- (I,II), N′-benzoyl- (III), N′-carboethoxy- (IV), and N′-p-toluene-sulfonyl derivatives (V, VI). It was found from the pH dependence of the apparent rate constant that the reactive species of a substrate varies with the pH of the medium, from an undissociated molecule to an anion formed by the ionization of an acylamino group. In the case of I, the activating effect of the dissociated acylamino group seems to be higher than that of the undissociated acylamino group by some 8 powers of ten.
The Synthesis of 1,2-Diamino- and 1,2,3-Triaminoazulene Derivatives
Authors: Nozoe Tetsuo , Asao Toyonobu , Kobayashi Masao 
Published: July 2006

Abstract
The diazo coupling reaction of 2-amino- (I), 2-acetamido-, and 2-amino-1-ethoxycarbonyl-azulene with p-toluene diazonium salt gave the corresponding l-(p-tolylazo)azulene derivatives, II, V, and VIII respectively, in good yield; 2-amino-1,3-di(p-tolylazo)azulene (III) was also obtained by the reaction of I and two molar equivalents of p-toluene diazonium salt. The catalytic reduction of V and VIII afforded 2-acetamido-1-aminoazulene and ethyl 1,2-diaminoazulene-3-carboxylate as hydrochloride. The similar reduction of II and III yielded only a resinous product, and 1,2-diamino- or 1,2,3-triaminoazulene could not be isolated, not even as their salts. However, the reductive acetylation of II and III afforded the corresponding polyacetamidoazulenes. The ultraviolet and visible absorption spectra of these azulenes are indicated.
Hydrolyses of p-Nitrophenyl(Oligodeoxyribonucleotide Succinate)s by Oligodeoxyribonucleotide N-Acetylhistidates on Polycytidylic Acid
Authors: Shimidzu Takeo , Letsinger Robert L 
Published: July 2006

Abstract
The hydrolyses of p-nitrophenyl(oligonucleotide succinate)s, in which the oligonucleotides are dGpG, dGpT, dGpC, dGpA, and dGpGpG, by oligonucleotide N-acetylhistidates, in which the oligonucleotides are dGpG, dGpT, dGpC, dGpA, and dGpGpG, or by dGpG nicotinate were carried on polycytidylic acid (Poly C). While the hydrolysis did not occur at lower concentrations of them, it did take place at moderate concentrations, in the presence of Poly C. From the kinetics of the hydrolysis, it was concluded that the interaction between those oligonucleotide derivatives and Poly C was homogeneous at lower concentrations of them and heterogeneous at higher concentrations. The change in the viscosity of the reaction system was correlated with the kinetical results. The heterogeneity in the interaction can be explained as a contiguous stacking of the oligonucleotide derivatives on Poly C. The tendency of the contiguous stacking was great in dGpGpG N-acetylhistidate. The rate of the hydrolysis of Poly C was higher than that without Poly C. The order in magnitude of the interaction between the oligonucleotide derivatives and Poly C was dGpGpG-derivative&gt;dGpGp-derivative&gt;dGpC-derivative&gt;dGpA-derivative&gt;dGpT-derivative.
Studies on Pyrophosphates II. A New Method for the Synthesis of Nucleotide Coenzymes and Their Analogs
Authors: Nakagawa Iwao , Hata Tsujiaki 
Published: July 2006

Abstract
A new method for the synthesis of unsymmetrical pyrophosphates from the reaction of alkyl phosphorothioates and disilver salt of alkyl phosphates are described. Nucleotide coenzymes such as uridine diphosphate glucose, uridine diphosphate galactose, and flavin adenine dinucleotide was synthesized.
Reactions of N-Acylaminoacetamidine with 1,3-Bifunctional Compounds
Authors: Uchida Hiroaki , Iwasawa Hiroyuki , Ohta Masaki 
Published: July 2006

Abstract
The reactions of N-benzoylaminoacetamidine(IIIa) and N-benzyloxycarbonylaminoacetamidine(IIIb) with various 1,3-bifunctional compounds were investigated. Both IIIa and IIIb were found to react with acetylacetone to produce 2-amino-3-benzoylamino-4,6-dimethylpyridine and 2-amino-3-benzyloxycarbonylamino-4,6-dimethylpyridine, respectively. On the other hand, IIIa reacted with ethyl acetoacetate or diketene to produce 2-(N-benzoylaminomethyl)-4-hydroxy-6-methylpyrimidine. Reaction of IIIb with malononitrile gave 1-amino-2-(N-benzyloxycarbonylaminoethylidene)malononitrile.
Arrangement of Acridine Orange in the Poly-α,l-glutamic Acid-Acridine Orange Complex
Authors: Sato Yukio , Hatano Masahiro 
Published: July 2006

Abstract
The temperature dependencies of the absorption and circular dichroism spectra of the poly-α,l-glutamic acid-acridine orange complex were observed at the temperatures in the range of 23–95 °C. The circular dichroism spectra were resolved into several Gaussian components by means of a computer online system. Thus, the circular dichroism spectrum can be resolved to five components. The shorter-wavelength bands, consisting of one positive and one negative element, were assigned to the transitions polarized parallel to and perpendicular to the axis of the α-helix of polypeptide respectively. On the other hand, the longer-wavelength bands, having equal magnitudes but signs opposite to each other, were assigned to the transition of the acridine orange dimer bound to polymer. The fifth band, at the shortest wavelength was uncertain. On the basis of these results, the arrangement of acridine orange molecules bound to poly-α,l-glutamic acid was discussed. Thus, two kinds of arrangements of acridine orange molecules were postulated. One is a left-handed super-helix around the right-handed α-helix of the polypeptide in the acidic pH region, and the other is a right-handed super-helix around the core of the α-helix in the alkaline pH region when the molar ratio of glutamyl residues to the dye is kept around unity. In these two complexes, there are dimeric acridine orange molecules bound to the polymer; in the latter complex, the super-helix consists of dimeric acridine orange molecules. Two types of arrangements of acridine orange molecules around the polypeptide were offered for the elucidation of the circular dichroism spectra of the complex of acridine orange with poly-α,l-glutamic acid in an aqueous solution.
The Primary Photochemical Process of 4-Nitropyridine N-Oxide. III. Its Photochemical Behavior in an Aqueous Solution
Authors: Hata Norisuke , Ono Isao , Osaka Kenji 
Published: July 2006

Abstract
4-Nitropyridine N-oxide does not undergo photochemical changes in an aqueous solution. When small amounts of 2-propanol or tetrahydrofuran were added to a deaerated solution, however, the 4-nitropyridine N-oxide was found to be reduced photochemically to afford 4-hydroxylaminopyridine N-oxide. From the measurements of the quantum yields and from flash-spectroscopic experiments under various conditions, such a photoinduced reduction of 4-nitropyridine N-oxide in deaerated water was revealed to be initiated by a hydrogen-atom abstraction from a 2-propanol or tetrahydrofuran by the triplet species. The situation was quite different from the case of an alcoholic solution, in which some intermediate species originating from the excited singlet state was responsible for the photoreduction.
Emission Spectra of Benzonitrile, Aniline, and Nitrobenezene by Controlled Electron Impact
Authors: Tsuji Masaharu , Ogawa Teiichiro , Ishibashi Nobuhiko 
Published: July 2006

Abstract
The emission spectra of benzonitrile, aniline, N,N-dimethylaniline, and nitrobenzene under controlled electron-impact excitation (60–300 eV) were investigated at a very low pressure. Bands of the parent molecules were observed in the 260–410 nm region on benzonitrile and anilines, and were assigned to the S1–S0 transitions. However, no emission of the parent molecule was observed on nitrobenzene and this was attributed to the spinorbit coupling effect of the nitro group and the predissociation of the excited parent molecule. Bands of the following fragment species were observed for all four compounds: H(Balmer series, CH(A2Δ2–X2II), and CN(B2Σ–X2Σ). In addition, NH(A3II–X3II) band on aniline and NO(A2Σ–X2II, B2II–X2II), CO(b3Σ–a3II), and CO+ (A2II–X2Σ, B2Σ–X2Σ) bands on nitrobenzene were observed. The linear relationships between the electron beam current and the emission intensities of the parent molecules and the fragment species indicated that most of the excited species were produced by primary electron-molecule collision processes (CN of anilines, CO, and CO+were found to be exceptional). The mechanism of the excitation and the fragmentation of the parent molecules and the comparison of the present spectra with those by discharge and by optical excitation were discussed. It was concluded that some excited species were produced through superexcited states.