bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vacuum UV Photolyses of Some Bichromophoric Alkenes Possessing Hydroxyl or Methoxycarbonyl Group
Authors: Inoue Yoshihisa , Goan Kazuyoshi , Hakushi Tadao 
Published: July 2006

Abstract
The direct photolyses at 185 nm of some naturally occurring and related bichromophoric alkenes possessing hydroxyl or methoxycarbonyl group at an allylic, homoallylic, or remote position gave the geometrical isomers as the major photoproducts detectable on gas chromatography. The isomerization yield was highly sensitive to the functional group introduced and its position; allylic alkenols gave poor yields, while both functionalization at a remote position and esterification of the hydroxyl group improve the photoisomerization yield.
Reactions of Dichloride Anion Radical with Nucleosides, Nucleotides, and Polynucleotides
Authors: Takahashi Takeo , Yamauchi Kotaro , Masuda Takahiro 
Published: July 2006

Abstract
Rate constants for reactions of dichloride anion radical with nucleosides, nucleotides, and polynucleotides were determined in neutral aqueous solutions of potassium chloride by the conventional flash photolysis. The reactivities of these compounds toward the anion radical are in the order: bases&gt;nucleosides&gt;nucleotides&gt;polynucleotides. This trend is similar to that observed with the corresponding reactions with hydroxyl radical. A comparison of the reactivities of nucleosides, nucleotides, and polynucleotides toward dichloride anion radical with those toward hydroxyl radical has revealed that the reactivities of these compounds are governed mainly by their base moiety. This trend in the reactivities is discussed in terms of steric effect.
Stereoselective Interaction of Chiral Metal Complexes in Solution as Studied by Chromatography. I. Modes of Chiral Discrimination and Optical Resolution of Anion Complexes
Authors: Miyoshi Katsuhiko , Sakamoto Yukio , Ohguni Atsuko , Yoneda Hayami 
Published: July 2006

Abstract
Chromatographic resolution of some anion complexes, [Co(ox)2(en)]−, C1- and C2-cis(N)-[Co(ox)(gly)2]−, [Co(ox)2(gly)]2−, and [Co(ox)2(acac)]2− (ox=oxalate ion, en=ethylenediamine, gly=glycinate ion, and acac=acetylacetonate ion), was attempted on an ion-exchange column using as chiral selectors several optically active cation complexes such as [Co(en)3]3+, [Co(sep)]3+, [Co(pn)3]3+, [Co(chxn)3]3+, [Co(acac)(en)2]2+, and [Co(gly)(en)2]2+ (sep=1,3,6,8,10,13,16,19-octaazabicyclo[6.6.6]icosane, pn=propylenediamine, and chxn=trans-1,2-cyclohexanediamine). The elution orders and degrees of optical resolution attained were interpreted on the basis that chiral discrimination is effected along either the C3 (or pseudo C3) axis or the C2 (or pseudo C2) axis of the respective complexes; the cation complex faces the anion complex with its N–H protons hydrogen-bonded to the coordinated oxygen atoms of the anion complex along the (pseudo) C3 or C2 axis. Plausible association models were proposed, which indicate that homochiral (i.e., Δ-Δ or Λ-Λ) and heterochiral (i.e., Δ-Λ or Λ-Δ) combinations are favored when the cation complex directs its C3 and C2 axes to the anion complex, respectively, regardless of which axis (C3 or C2) of the anion complex is directed to the cation complex. Most of the experimental data are consistently explained within the framework of the association models proposed.
The Prediction of Preferred Orientation Planes in X-Ray Powder Diffractometry
Authors: Takaki Yoshito , Yamaguchi Hiroshi , Nakata Kazuaki 
Published: July 2006

Abstract
A method for predicting possible preferred orientation planes in organic and inorganic powders of known crystal structures is presented. The usefulness of this method is demonstrated by applying it to the powders of benzamide, the α-form of 2-pyrazinecarboxamide, benzoic acid, olivine, and the high-temperature form of Li3PO4. It should be noted that the existence of preferred orientation axes found in the powders of benzoic acid and Li3PO4 can be well explained in terms of zone axes, each formed by two sets of cleavage planes.
Electronic Structures of 3,4:3′,4′-Bis(tetramethylene)-2,2′,5,5′-tetrathiafulvalene–TCNQ and 3,4:3′,4′-Bis(tetramethylene)-2,2′,5,5′-tetrathiafulvalene-1,4-Dihydro-1,4-bis(dicyanomethylene)triptycene Complex Crystals
Authors: Akhtar Shamim , Tanaka Jiro , Nakasuji Kazuhiro , Murata Ichiro 
Published: July 2006

Abstract
Experimental results of the polarized reflection spectra and the calculated absorption spectra of 3,4:3′,4′-bis(tetramethylene)-2,2′,5,5′-tetrathiafulvalene (OMTTF)–TCNQ and OMTTF–1,4-dihydro-1,4-bis(dicyanomethylene)triptycene(DBTCNQ) crystals are discussed by developing approximate theoretical models, based on the CT mechanism. The electronic structures conform well that, OMTTF–TCNQ is a neutral crystal whereas, OMTTF–DBTCNQ is ionic. Furthermore, the temperature dependent spin susceptibilities imply the former as diamagnetic and the latter as a regular Heisenberg antiferromagnet.
NMR Study of Molecules in Anisotropic Systems. II. 1a,2a,3e,4e,5e,6e- and 1e,2e,3e,4e,5e,6e-Hexachlorocyclohexanes Dissolved in Nematic Liquid Crystals
Authors: Fujiwara Hideaki , Shimizu Naoto , Takagi Tatsuya , Sasaki Yoshio 
Published: July 2006

Abstract
NMR spectra of the titled compounds (α- and β-BHC) have been measured in nematic solvents and analyzed. Vibrational corrections were important for the full interpretation of the observed direct couplings. The order parameters showed that the BHC molecules orient most preferably with their six-membered rings parallel to the optic axis of the nematic solvents. Molecular structure of α-BHC derived from the direct couplings corresponds well with those determined by the X-ray method on a crystal and calculated by the MNDO MO method. For β-BHC, however, discrepancies are found with the crystallographic structure, suggesting molecular deformations in the crystal state. Principal axes have been determined for the order matrix and compared with those for the moment of inertia. The difference between the two principal axis systems in α-BHC is interpreted as due to a steric repulsive effect between the two axial chlorine atoms and the solvent molecules.
NMR Studies of Picolyl-type Carbanions. VIII. Anions Produced by Reactions of Alkyl-substituted Pyridines with Butyllithium
Authors: Konishi Kazuyori , Matsumoto Hiroshi , Saito Katsuhiro , Takahashi Kensuke 
Published: July 2006

Abstract
The 1H and 13C NMR spectra have been observed for the anions, produced from methyl-, ethyl-, and isopropylpyridines, in tetrahydrofuran (THF). Two kinds of anions are formed concomitantly by lithium-proton exchange and addition of butyllithium from 2-ethyl-, 2-isopropyl-, 4-methyl-, and 4-ethylpyridines. The former reaction tends to occur at the substituent bonded to the position adjacent to nitrogen, and the latter one occurs at the position adjacent to nitrogen without substituent. In the anions formed by the exchange from 2- and 4-ethylpyridines, a specific ring proton is coupled to the α-carbon, and, further, the ortho- or meta- protons (or -carbons) in the latter anion are nonequivalent respectively at room temperature. The α-carbons in these anions are virtually sp2-hybridized.
Effect of High Surface Coverage on the Rate of Methanol Oxidation at Platinum Electrode
Authors: Matsui Hiroshi , Hisano Takeo 
Published: July 2006

Abstract
The rates of the methanol oxidation and the COad formation at Pt electrodes in solutions of CH3OH+0.5 mol dm−3 H2SO4 were investigated under the conditions minimizing the harmful effect of impurities. Under the particular conditions, the both rates decreased remarkably towards zero at a limiting coverage of about 0.8. Namely, the COad hindered both the formation of the COad itself and the oxidation of methanol via some unidentified intermediate other than COad. This fact was explained by assuming an aggregate with two vacant sites indispensable for the COad formation and the methanol oxidation to CO2.
Carbon-13 NMR Chemical Shift and Electronic Structure of Solid Polypeptides as Studied by Tight-binding MO Theory. Polyglycine and Poly(l-alanine)
Authors: Yamanobe Takeshi , Ando Isao , Saito Hazime , Tabeta Ryoko , Shoji Akira , Ozaki Takuo 
Published: July 2006

Abstract
A tight-binding MO-sum-over-state theory has been used to calculate the 13C NMR chemical shift of polyglycine having the forms I and II and that of poly(l-alanine) having the α-helix and β-sheet forms, in order to justify the origin of the conformation-dependent 13C NMR chemical shift previously determined by the cross polarization-magic angle spinning technique. The calculated results on the carbonyl, Cα and Cβ carbons were found to exhibit the conformation-dependent 13C NMR chemical shifts comparable with the experimental data.
The Solution Chemistry of Organotin Compounds. IV. Thermodynamic Parameters of the Complex Formation between MeSnCl3 and Alkyl Sulfoxides Determined from Titration Calorimetry
Authors: Fujiwara Hideaki , Sakai Fumihiko , Kawamura Akio , Shimizu Naoto , Sasaki Yoshio 
Published: July 2006

Abstract
Calorimetric titration data have been analyzed to determine thermodynamic parameters of the interacting system. The system studied is MeSnCl3 plus dialkyl sulfoxide in CH2Cl2 and a nonlinear least squares method is utilized to simulate the titration curve. The 1:1 and 1(acid):2(base) complexes are found to coexist in solution, and the effect of alkyl chain length on the complex formation is examined. The complex formation proceeds most favorably under the total carbon number of four, and inductive and steric effects are considered to operate in a compensating way. Entropy changes on the reactions are discussed with the aid of molecular theory of thermodynamic functions, and a new method is suggested that affords the number of solvent molecules released on the complex formation.
Photoregulated Ion-binding to Azobenzene-linked Ethylenediamines and Iminodiacetic Acids
Authors: Shinkai Seiji , Nakamura Shinichiro , Nakashima Mikio , Manabe Osamu , Iwamoto Masakazu 
Published: July 2006

Abstract
New photoresponsive complexones bearing two iminodiacetic acid units or ethylenediamine units at the two sides of an azobenzene through CH2 or (CH2)2 (AzoIDA(n=1,2) and AzoED(n=1,2), respectively) have been synthesized. The CH2 and (CH2)2 spacers were selected in order to examine the influence of the spacer length on the intramolecular cooperativity for the two ligands in the cis-isomers to coordinate to one metal ion. The thermal cis-to-trans isomerization of AzoIDA was efficiently suppressed by Zn(II) and Cu(II) while that of AzoED was suppressed only by Cu(II). The rate suppression supports the formation of the intramolecular chelate complexes with the metal ion. The measurements of ESR spectra of the cis-isomer·Cu(II) complexes indicated that the square-planar structure of the complexes is somewhat distorted and probably close to a lozenge. The stability constants (Ks) were determined by a displacement method. The Ks values for the cis-isomers were generally greater than those for the trans-isomers, and the Ks for n=2 series increased more clearly. In particular, the Ks for cis-AzoED(n=2)+Cu(II) was improved by 43.8 fold. The photoresponsive change in the stability constants suggests a possible application of the present system as light-driven ion pumps for heavy metal ions.
Reactivities of Stable Rotamers. XIV. Reaction of 9-[2-(Substituted Methyl)-6-methylphenyl]fluorene Rotamers with Butyllithium
Authors: Nakamura Mikio , Suzuki Yoshio , Oki Michinori 
Published: July 2006

Abstract
The title compounds of which substituents carry atoms with lone-pair electrons have been prepared and their rotamers isolated as stable entities at room temperature. Deprotonation rates of these rotamers with butyllithium in benzene–hexane solution show a striking difference depending upon the substituents and the rotamers. In both sp and ap series, compounds with a methoxyl group exhibit the largest rate constants, while those with a sulfur substituent show the smallest reactivity. The difference is explained in terms of coordination ability of the heteroatoms toward butyllithium and by taking advantage of the entropy effect at the transition state of lithiation. The difference in reactivities between rotamers is further striking in a sense that the reactions differ in the order; sp rotamers show the first-order kinetics while ap rotamers obey the second-order kinetics in the substrate. By assuming that the observed rates are the sum of the first-order and the second-order contributions, we estimate the minimum ratios of the first-order rate constants between sp and ap rotamers, k1sp⁄k1ap, to be &gt;2300 in the methoxyl and dimethylamino derivatives and &gt;240 in the methylthio derivatives.
Crystal Structure of Potassium Dithizonate
Authors: Noda Hiroshi , Engelhardt Lutz Meinhardt , Harrowfield Jack MacBean , Pakawatchai Chaveng , Patrick Jennifer Mary , White Allan Henry 
Published: July 2006

Abstract
The crystal structure of potassium dithizonate, K+[C6H5·NH·N·CS·N:NC6H5]−, has been determined by single crystal X-ray diffraction methods at 295 K and refined by full matrix least squares to a residual of 0.045 for 1101 independent “observed” reflections. Crystals are orthorhombic, Pbca, a=28.942(9), b=13.247(4), c=7.163(3)Å, Z=8. The structure determination is the first carried out on a salt rather than a complex of the anion. The pseudo-planar anion stacks parallel to the ab face of the cell with considerable delocalization evident; as indicated by the above formula, the remaining acidic hydrogen atom is associated with one of the nitrogen atoms.
Cyclizations of Dianions from 2-Imino-1,2-diphenylethanone to Oxazolines, Oxazocines, and Oxazonines
Authors: Mehrotra Kailash Nath , Singh Indra Sen , Roy Jalpana 
Published: July 2006

Abstract
The reaction of 2-imino-1,2-diphenylethanone with sodium in ether and subsequent addition of carbon disulfide or ethyl chloroformate resulted in the formation of 3,4,5-trisubstituted 4-oxazoline-2-thiones and 2-ones, respectively. 1,4-Oxazonines and 1,4-oxazocines were also synthesised from the reaction of 2-imino-1,2-diphenylethanone with sodium in THF followed by addition of dihaloalkanes.
Remarkable Isotope Effect on the Hydrogen-atom Reaction in the Photolysis of D2–H2–HI Mixtures at 4 K. A Quantum-mechanical Tunneling Effect
Authors: Miyazaki Tetsuo 
Published: July 2006

Abstract
The photolysis of D2–H2–HI (0.05 mol%) mixtures has been studied at 4 K by means of ESR spectroscopy. The yield of D atoms decreases sharply upon the addition of a small amount of H2, while the yield of H atoms increases. The results of the photolysis are similar to those in the radiolysis of D2–H2 mixtures at 4 K. The preferential formation of H atoms in the photolysis and radiolysis of the D2–H2 mixtures is due to the selective H-atom-abstraction reaction from H2 by D atoms by means of a quantum mechanical tunneling.
Electrochemical Reductive Acylation of 2,3-Disubstituted 1-lndenones
Authors: Takano Nobuhiro , Takeno Noboru , Morita Mutsuo , Otsuji Yoshio 
Published: July 2006

Abstract
The electrochemical reductive acylation of 2,3-disubstituted 1-indenones in the presence of acetic anhydride in aprotic media such as DMF, DMSO, and aceto-nitrile gave 2,3-disubstituted 1-acetoxy-1H-indenes (2) and 1,2-disubstituted 3-acetoxy-1H-indenes (3) in good yields. The ratios of 2 to 3 in the products were affected by the substituents.
Palladium-catalyzed Ketone Synthesis from Acyl Chloride and Organoaluminum Reagents
Authors: Wakamatsu Kuni , Okuda Yasuhiro , Oshima Koichiro , Nozaki Hitosi 
Published: July 2006

Abstract
The reaction of organoaluminum reagents with acyl chloride catalyzed by Pd(PPh3)4 in tetrahydrofuran provides ketones in fair yields.
New Crossed Aldol Reaction. Reaction of Enamines with Aldehydes Activated by Lewis Acids
Authors: Takazawa Osamu , Kogami Kunio , Hayashi Kazuo 
Published: July 2006

Abstract
Enamines react with aldehydes in the presence of Lewis acids such as BF3·OEt2 to give the corresponding crossed aldol products in good yields. Reaction of dienamines with aldehydes gives the corresponding β,γ-unsaturated α-(1-hydroxyalkyl) carbonyl compounds.
Rates of Thermal Decomposition of t-Butyl Peroxypivalate
Authors: Komai Takeshi , Ishigaki Hideyo , Matsuyama Kazuo 
Published: July 2006

Abstract
The kinetics of decomposition of t-butyl peroxypivalate in benzene, hexane and mineral spirits were determined iodometrically in the temperature range 50–75°. The decomposition in benzene indicated smaller rate constants and activation parameters than those in hexane or mineral spirits. The solvated transition state in aromatic solvent is discussed on the basis of these results and the previously published data.
Charge-transfer Complexes of 11,11,12,12-Tetracyanoanthraquinodimethans with Various Donors
Authors: Mukai Toshio , Suzuki Takanori , Yamashita Yoshiro 
Published: July 2006

Abstract
Titled compounds were found to form charge-transfer (CT) complexes with aromatic hydrocarbons or tetrathiafulvalene (TTF) and the molecular complexes could be isolated.
A New Chamigrane-type Bromo Diether from the Red Alga Laurencia nipponica Yamada
Authors: Kikuchi Hajime , Suzuki Teruaki , Suzuki Minoru , Kurosawa Etsuro 
Published: July 2006

Abstract
A new halogenated sesquiterpene diether has been isolated from the title alga and its structure was established on the basis of the spectral and chemical evidence.
Irreversible Conformational Change of the Complex of Poly(l-lysine) with Methyl Orange upon Irradiation of Light
Authors: Yamamoto Hiroyuki 
Published: July 2006

Abstract
The effect of light on the chiral complex of poly(l-lysine) (PLL) with Methyl Orange (MO) was studied by means of absorption and circular dichroism (CD) measurements. Upon irradiation, the magnitude of the induced CD of the PLL–MO complex decreased together with a decrease in dimeric dye species. The change was irreversible under dark or visible-light conditions.
A Facile Synthesis of 2-Acyl-3-amino-5-phenacylthio-4-phenylthiophenes from Sodium Cyanophenyldithioacetate and α-Halo Ketones
Authors: Fuchigami Toshio , Kandeel Zaghloul El-Shahat , Nonaka Tsutomu 
Published: July 2006

Abstract
Various kinds of α-halo ketones readily reacted with sodium cyanophenyldithioacetate to provide 2-acyl-3-amino-5-phenacylthio-4-phenylthiophenes in good yields.
The Reaction of Cyclopropenethione with Carbonyl-stabilized Phosphonium Methylides to Yield 2H-Pyran-2-thione
Authors: Yoshida Hiroshi , Shimizu Jyun , Ogata Tsuyoshi , Matsumoto Kiyoshi 
Published: July 2006

Abstract
The reaction of diphenylcyclopropenethione with carbonyl-stabilized triphenylphosphonium methylides (2) to yield 2H-pyran-2-thiones was studied. It was clarified that electron-releasing substituents increased the reactivity of 2.
Rapid Spectrophotometric Determination of Chromium(III) with 1-(2-Thiazolylazo)-2-naphthol in Presence of Surfactant
Authors: Rathaiah Gogineni V , Eshwar Muppalla C 
Published: July 2006

Abstract
Chromium(III) reacts with 1-(2-thiazolylazo)-2-naphthol at 80–95°C in acid media (pH 5.7), in presence of benzoate and sodium dodecyl sulfate. Presence of surfactant increases sensitivity of the complex and reduces heating time to 5 min, thus giving rise to perhaps the most rapid method for absorptiometric determination of chromium(III). The 1:1 complex obeys Beer’s law for 0.2 to 2.4 μg of Cr(III) per ml, has molar absorptivity and Sandell sensitivity of 1.46×104 dm3mol−1cm−1 and 3.5 ng cm−2 respectively, at 575 nm.
Synthesis of New Heterocycles: Condensation of 2-Methyl-4H-naphth[1,2-d][1,3]oxazin-4-one with Schiff Bases and Formation of 3-Aryl-2-styrylbenzo[h]quinazolin-4(3H)-ones
Authors: Reddy Mandala Satyanarayana , Ratnam Chengalvala Venkata 
Published: July 2006

Abstract
Condensation of 2-Methyl-4H-naphth[1,2-d][1,3]oxazin-4-one (2) with Schiff bases (3) in acetic acid has resulted in 3-aryl-2-styrylbenzo[h]quinazolin-4(3H)-ones (4), characterized by spectral and analytical methods.
Studies on the Hydrous Niobium(V) Oxide Ion Exchanger. I. A Method for Synthesis and Some Properties
Authors: Inoue Yasushi , Yamazaki Hiromichi , Kimura Yasuyuki 
Published: July 2006

Abstract
A comprehensive study of the preparation of hydrous niobium(V) oxide ion exchangers was made using three kinds of niobium solutions: (1) HCl, (2) C2H5OH, and (3) H2SO4. From a detailed examination of the dependency of the yield, the ion-exchange behavior toward Na+, the chemical stability, and some other properties, regarding the method for precipitation, it was found that the pyrohydrolysis of the NbCl5 solution was the best method, since the procedure was simple, rapid and reproducible, and the product had a comparatively good ion-exchange property. The product obtained from the H2SO4 solution had the largest ion-exchange capacity and was most stable in highly alkaline solutions, but the whole procedure was very tedious. The exchanger prepared from the ethanolic solution had a smaller ion-exchange capacity in a pH region higher than 8. The materials, thus obtained, had at least two kinds of weakly dissociable ion-exchange sites, and the ion-exchange capacity for alkali metal ions decreased in the order of Li+&gt;Na+&gt;K+. The aging effect and the chemical stability were also examined.
Functionalized Dithia(2,5)pyridinophanes as Vitamin B6 Analogues. Synthesis, Properties, and Catalytic Activity for Racemization Reaction
Authors: Iwata Masaaki , Kuzuhara Hiroyoshi 
Published: July 2006

Abstract
Exploration of synthetic routes to achieve designed vitamin B6 models on the structural basis of functionalized dithia(2,5)pyridinophanes from pyridoxine hydrochloride was undertaken and the catalyst potency for a racemization reaction was examined in comparison with that of pyridoxal. By the reaction of 3,4′-O-isopropylidenepyridoxine 2′,5′-dichloride with α,ω-dithiols, dithia(2,5)pyridinophanes were synthesized in good yields. For dithia[3]paracyclo[3](2,5)pyridinophanes, juncture sulfur atoms were extruded photochemically, whereas 2,(n+3)-dithia[m](2,5)pyridinophanes incompletely extruded sulfur atoms under various conditions. Because of instability and low preparative yield of 15-hydroxy-16-formyl[2]paracyclo[2](2,5)pyridinophane, dithia-containing phanes, (n+9)-hydroxy-(n+10)-formyl-2,(n+3)-dithia[m](2,5)pyridinophanes [26a (n=4), 26b (n=6), 26c (n=8); m=n+4], 17-hydroxy-18-formyl-2,11-dithia[3]paracyclo[3](2,5)pyridinophane (27), and an acyclic congener for 26a, 5′-deoxy-2′,5′-bis(ethylthio)pyridoxal (28), were eventually prepared in high yields by use of manganese dioxide in the presence of a primary amine. It was found on the basis of 1H-NMR spectral analyses that the rotations of pyridine rings in some molecules, 26a, 26b, and 27 with ring sizes equal to or less than fourteen were restricted. The racemization potency of 26a–c, 27, and 28 for sodium hydrogen l-glutamate demonstrated that these are 1.4- to 1.7-fold more potent than pyridoxal itself under certain conditions (pH 10.0, 25±0.5 °C) until ca. 80% completion of the racemization reaction. 26a was found to be quite stable (no decomposition), but the others, 26b, 26c, and 28, indicated 14, 8, and 12% decomposition, respectively. 27 was so unstable that a 63% decomposition was marked at the time of 56% completion of the racemization reacion.