bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Synthesis of Megastigma-4,6,8-trien-3-ones, 3-Hydroxy-β-ionol, 3-Hydroxy-β-ionone, 5,6-Epoxy-3-hydroxy-β-ionol, and 3-Oxo-a-ionol
Authors: Takazawa Osamu , Tamura Hiroshi , Kogami Kunio , Hayashi Kazuo 
Published: July 2006

Abstract
The Lewis acid-catalysed reaction of 1-trimethylsiloxy-1,3-cyclohexadienes with aldehydes and trialkyl orthoformates afforded the corresponding 4-substituted 2-cyclohexenones. A new reaction of 2,4,6-trienones with m-chloroperbenzoic acid followed by the reduction with zinc in acetic acid gave 7-hydroxy-3,5-dienones. Utilizing these efficient reactions, megastigma-4,6,8-trien-3-ones, 3-hydroxy-β-ionol, 3-hydroxy-β-ionone, 5,6-epoxy-3-hydroxy-β-ionol, and 3-oxo-α-ionol were successfully synthesized.
Oxidative S-Dealkylation Reaction of Sulfide Catalyzed by Co(II)(bzacen)
Authors: Watanabe Yoshihito , Numata Tatsuo , Oae Shigeru 
Published: July 2006

Abstract
In the oxygenation reaction of alkyl sulfides with Co(II)(bzacen)–O2 system, oxidative S–C bond cleavage (S-dealkylation) was found to take place exclusively. The reactivity of S-dealkylation reaction was dependent markedly on both acidity of α-methylene and steric hindrance of alkyl sulfide. The peroxo-Co(III) species is presumed to be the intermediate in this S-dealkylation reaction.
Manufacture of High Pure Titanium(IV) Oxide by the Chloride Process. I. Kinetic Study on Leaching of Ilmenite Ore in Concentrated Hydrochloric Acid Solution
Authors: Tsuchida Hisashi , Narita Eiichi , Takeuchi Hitoshi , Adachi Masahiro , Okabe Taijiro 
Published: July 2006

Abstract
Kinetic study of the leaching of powdered ilmenite ore was carried out in highly concentrated hydrochloric acid (11.3–11.6 mol dm−3) at temperatures of 30 to 80 °C. The changes in shape and grain size of the ore particles with progress of the leaching was simultaneously observed with X-ray diffraction and electron microscope techniques. Titanium and iron were dissolved in a nearly stoichiometric ratio; the rate of the dissolution was significantly affected by the temperature of the acid solutions. From the analysis of the dissolution rates on the basis of the core-model, it was found that the dissolution rates at temperatures of 30 to 50 °C were well expressed by the rate equation based on the rate-determining step of the surface chemical reaction. The apparent activation energies were 81.2 kJ mol−1 for titanium and 73.2 kJ mol−1 for iron. The rate-determining step of the dissolution was changed at a temperature of about 50–60 °C; the dissolution rates at temperatures of 60 to 80 °C were limited by the diffusion of the dissolved metal ions through a residual layer of the ore. However, the rates after 2 or 3 h at high temperatures deviated from the rate equation because of the precipitation of hydrous titanium(IV) oxide on the surface of the ore by hydrolysis of the dissolved titanium(IV) ion.
Reaction of Electroehemically Generated Radical Anion of Thioketone with Alkylating Agents
Authors: Yasui Shinro , Nakamura Kaoru , Ohno Atsuyoshi , Oka Shinzaburo 
Published: July 2006

Abstract
Electrochemically generated anion radicals of thioketones were allowed to react with alkyl halides (or tosylate). Electronic structure of the anion radical is discussed on the basis of the products.
Studies on Heteropentalenes. IV. Heteroannelations to Pyrrolo-[2,1-b]benzothiazole and Pyrrolo[2,1-b]thiazoles
Authors: Abe Noritaka , Nishiwaki Tarozaemon , Omori Toshimasa , Harada Emiko 
Published: July 2006

Abstract
2,3-Dibenzoylpyrrolo[2,1-b]benzothiazole (2) and 6,7-dibenzoylpyrrolo[2,1-b]thiazoles (5a–b) have been synthesized by utilizing the cycloaddition reactions of imidazo[2,1-b]benzothiazole and imidazo[2,1-b]thiazoles, respectively, with dibenzoylacetylene followed by the elimination of a nitrile from each of the cycloadducts. Heteroannelations to 2 and 5 have been achieved by their reactions with hydrazine, aminoacetonitrile, ethyl glycinate, and phosphorus pentasulfide. The annelations by the second and third reagents proceed fairly regioselectively. Facile dimerizations of thieno[3′,4′:3,4]pyrrolo[2,1-b]benzothiazole and thieno[3′,4′:3,4]pyrrolo[2,1-b]thiazoles to be produced by the reactions with the last reagent are also described.
Experimental and Calculated Magnetic Circular Dichroism Spectra of Iron(II) Low Spin Hemoglobin and Myoglobin with CO, NO, and O2
Authors: Yamamoto Takao , Nozawa Tsunenori , Kaito Akira , Hatano Masahiro 
Published: July 2006

Abstract
The ratios of the apparent Faraday A terms to the dipole strengths (A′⁄D) were obtained from the experimental magnetic circular dichroism (MCD) data for the iron(II) low spin derivatives of human hemoglobin and its α and β chains, and myoglobins (whale and bovine). The observed MCD peak height and trough depth exhibit the decreasing order of CO&gt;O2&gt;NO in the Soret band and O2&gt;CO&gt;NO for the Q band. The moment analysis also showed the decreasing order of the A′⁄D values of CO&gt;O2&gt;NO in the Soret bands for all hemoglobin and myoglobin derivatives experimentally studied. The molecular orbital calculation of the porphyrin π electron system based on the PPP CI approximation method demonstrated that the calculated spectra for the pyrrole nitrogen core-charge of 1.5 showed characteristics for the CO complex of hemoglobin and myoglobin, and that the NO and O2 complexes could be simulated by the calculations for the core charge values smaller than 1.5 (i.e. 1.4–1.3). These results suggest that the change in the porphyrin π electronic state which is caused by the electronic interaction between the diatomic molecule such as CO, NO, or O2 and the heme iron can be explained by the change in the σ core charge in the pyrrole nitrogen possibly through changes in the electronic states of the heme iron.
Surface Free Energies of Two Kinds of Graphite Fluorides, (CF)n and (C2F)n
Authors: Watanabe Nobuatsu , Nakajima Tsuyoshi , Ohsawa Noboru 
Published: July 2006

Abstract
The surface free energies of two kinds of graphite fluorides, (CF)n and (C2F)n, were estimated from the contact angles of several liquids. The contact angles of water on flaky (CF)n and (C2F)n were 117° and 116°, respectively, being slightly larger than that for poly(tetrafluoroethylene), while the values for tablets of powdery (CF)n and (C2F)n were 143° and 141°, respectively, which indicates that powdery graphite fluoride is hardly wetted by water. From the contact angles obtained, the surface free energies were estimated to be ca. 18 mJ/m2 for both flaky (CF)n and (C2F)n, ca. 2 mJ/m2 for powdery (CF)n and ca. 3 mJ/m2 for powdery (C2F)n. These differences depend on the surface conditions such as the packing of fluorine atoms, the roughness and porosity. From the contact angles for the tablets of (CF)n–polyethylene mixtures, it is suggested that the anode effect in the fluorine or aluminium electrolysis takes place when the surface of carbon anode is partially covered by graphite fluoride.
Structural Studies of Partially Oxidized One-dimensional Bis(oxalato)-platinate Salts Containing Bivalent Cations: Ni0.84[Pt(C2O4)2]·6H2O
Authors: Kobayashi Akiko , Kondo Hidetaka , Sasaki Yukiyoshi , Kobayashi Hayao , Underhill Allan E , Watkins David M 
Published: July 2006

Abstract
Fundamental structure, kF and 2kF satellite reflections, and electrical properties of Ni0.84[Pt(C2O4)2]·6H2O (Ni–OP) were determined. Complex Ni–OP crystallizes in the orthorhombic space group Pccn with cell parameters of a=14.296(2), b=16.387(3), and c=5.671(1) Å and Z=4. Ni–OP is essentially isostructural with Mg–OP (Mg0.82[Pt(C2O4)2]·5.3H2O) and Co–OP (Co0.83[Pt(C2O4)2]·6H2O). The space group of Mg–OP and Co–OP is Cccm. Owing to the change in the space group, there are two independent Pt chains in Ni–OP. X-Ray studies of M–OP (M=Co, Ni) show that there exist strong kF satellite spots and weak 2kF spots. One M2+ cation is vacant per period of the lattice modulation wave of the platinum chain, λ2kF. The periodic cation defect induces the kF modulation waves. The 2kF waves do not have a Peierls origin but are induced by the kF modulation wave. A second order phase transition is observed at about 305 K above which the 2kF spots disappear.
Cobalt(II)-substituted Horseshoe Crab Hemocyanins
Authors: Suzuki Shinnichiro , Kino Jun , Nakahara Akitsugu 
Published: July 2006

Abstract
The horseshoe crab Co(II) hemocyanins were prepared by dialyses of Tachypleus tridentatus, Tachypleus gigas, Limulus polyphemus, and Carcinoscorpius rotundicauda apohemocyanins against Tris–HCl buffer (pH 8.0) containing Co(II) ion. The amounts of Co(II) introduced into apohemocyanins reached almost 100% of the total sites for copper ion in native hemocyanins. However, all the four Co(II) hemocyanins did not take up oxygen molecule at all. The extremely similar spectral data for the four species revealed that there is no essential difference in the structure of the respective active sites. Both the two Co(II) ions at an active site are in the high spin state and in an distorted tetrahedral geometry, having no such ligating groups as cysteinyl or methionyl sulfur, but at least three nitrogenous ligands, probably histidine imidazoles. On the basis of these data, the environment of active site in native horseshoe crab hemocyanin is discussed.
A Potentiometric Study on Mixed Ligand Cadmium(II) Complexes with 2-Pyridinecarboxylic Acid and 2-Aminoalkanoic Acids
Authors: Matsui Haruo , Ohtaki Hitoshi 
Published: July 2006

Abstract
Formation constants of cadmium(II) complexes with 2-pyridinecarboxylic acid (Hpic) were determined in aqueous solutions containing 3 mol dm−3 LiClO4 as a constant ionic medium at 25 °C by potentiometric titrations. On the basis of the formation constants of the complexes thus determined and those of the 2-aminoalkanoate complexes previously obtained, formation constants of mixed ligand cadmium(II) complexes CdL(pic) were determined, where L− denotes a 2-aminoalkanoate ion such as glycinate (gly−), α-alaninate (ala−), 2-aminobutanoate (but−), 2-aminopentanoate (pen−), or 2-aminohexanoate (hex−) ion. The formation constants logβ111=log {[CdL(pic)]/([Cd2+][L−][pic−])} of the 1:1:1 mixed ligand cadmium(II) complexes are: Cd(gly)(pic), 8.88; Cd(ala)(pic), 8.47; Cd(but)(pic), 8.42; Cd(pen)(pic), 8.73; and Cd(hex)(pic), 8.76. The equilibrium constant of the reaction between Cd(gly)+ and pic− was larger than that between Cd(pic)+ and gly−, and much larger than the equilibrium constants between CdL+ and L′− previously studied, where L− and L′− are 2-aminoalkanoate anions.
Solute-Solvent Interactions in Ion Pair Extraction of Tetraalkylammonium Iodides. II. The Effect of Hydration of Iodide in Organic Solvents on the Extraction Constant
Authors: Ito Kazuaki , Iwamoto Etsuro , Yamamoto Yuroku 
Published: July 2006

Abstract
Solubilities of tetraalkylammonium iodides Et4NI, Pr4NI, and Bu4NI in nitrobenzene, in water, and in their mutually saturated solvents, and of Pr4NI in 1,1-dichloroethane and in its water saturated solvent were measured at 25 °C. Conductances of Et4NI, Pr4NI, and Bu4NI in nitrobenzene and Bu4NI in 1,1-dichloroethane, 1,2-dichloroethane, and dichloromethane have also been measured at 25 °C. A small amount of water in organic solvents increases the solubilities of the salts roughly twice those in pure solvents and decreases the association constants around 15% while a small amount of organic solvent in water gives a slight effect. Effects of mutual saturation of water and organic solvent on extraction equilibria of R4NI were discussed in terms of the selective hydration of the iodide.
Synthesis and Cation-complexing Ability of Oxo Crown Ethers
Authors: Matsushima Kenji , Kawamura Norio , Nakatsuji Yohji , Okahara Mitsuo 
Published: July 2006

Abstract
3-Substituted 2-oxo crown ethers and a novel dioxo crown ether with a point symmetry were synthesized by the cyclization of the corresponding substituted oligoethylene glycol monocarboxymethyl ethers using benzenesulfonyl chloride in the presence of alkali metal carbonates. The reaction mechanism was discussed. Their stability constants toward sodium and potassium cations were determined and the relation between their structures and complexing properties was discussed.
The Preparation of Optically Pure 3-Hydroxyalkanoic Acid. The Enantioface-differentiating Hydrogenation of the C=O Double Bond with Modified Raney Nickel. XXXVII.
Authors: Nakahata Masaaki , Imaida Motomasa , Ozaki Hiroshi , Harada Tadao , Tai Akira 
Published: July 2006

Abstract
The enantioface-differentiating hydrogenation of methyl 3-oxoalkanoate (CH3(CH2)nCOCH2COOCH3, n=0, 6, 8, 10, 12) over the (R,R)-tartaric acid–NaBr–modified Raney nickel catalyst ((R,R)-TA–NaBr–MRNi) gave methyl (R)-3-hydroxyalkanoate (CH3(CH2)nCH(OH)CH2COOCH3, n=0, 6, 8, 10, 12) in an average optical yield of 85%. After the methyl ester had been converted to dicyclohexylammonium salt of 3-hydroxyalkanoic acid, the salt was recrystallized three times from acetonitrile and then treated with acid to give optically pure (R)-3-hydroxyalkanoic acid (CH3(CH2)nCH(OH)CH2COOH, n=0, 6, 8, 10, 12) in a reasonable yield. From the hydrogenation product with (S,S)-TA–NaBr–MRNi, optically pure (S)-3-hydroxyalkanoic acid was obtained by the same process as above.
Stereospecific Synthesis of (2Z,4E,6E)-3,7,11-Trimethyl-2,4,6,10-dodecatetraene [trans(C10)-Allofarnesene]
Authors: Miyaura Norio , Suginome Hiroshi , Suzuki Akira 
Published: July 2006

Abstract
The stereospecific synthesis of the title acyclic sesquiterpene, isolated from Perilla frutscens f. viridis Makino (Japanese name, Aojiso) by the palladium-catalyzed cross-coupling of 2-(4,8-dimethyl-1,3,7-nonatrienyl)-1,3,2-benzodioxaborole with (Z)-2-bromo-2-butene, is described. The benzodioxaborole was prepared by the hydroboration of 4,8-dimethyl-3,7-nonadien-1-yne, newly prepared via three steps from geranial, with 1,3,2-benzodioxaborole.
Lanthanoid Shift Reagents. Synthesis and Spectral Studies
Authors: Iftikhar Khalid , Sayeed Mohammad , Ahmad Naseer 
Published: July 2006

Abstract
The seven coordinate adducts of [Ln(fod)3]chelates are described. The NMR spectra of diamagnetic and paramagnetic adducts have been discussed. The europium, praseodymium and ytterbium adducts have been scanned as potential shift reagents and these seven coordinate adducts produce large dipolar shifts in the proton magnetic resonances of organic moieties. The dipolar shift produced by [Eu(fod)3(pz)] in the spectrum of benzyl alcohol is different from that reported. Some interelectronic and spectral parameters (\barβ, b1⁄2, and δ) have been calculated. Ligand field parameter (Tλ) and oscillator strengths have been computed and discussed.
Efficiency of Noble Metal Electrodes for Zirconia Oxygen Sensors in Detecting Oxygen at Lower Temperatures
Authors: Arakawa Tsuyoshi , Saito Akira , Shiokawa Jiro 
Published: July 2006

Abstract
Metal Au, Ag, or Pt was deposited as electrode on the closed end of a stabilized electrolyte tube in the ZrO2 oxygen sensor, and emf of the cell, O2|m|ZrO2–Y2O3|m|O′2; (m=Au, Ag, Pt) with PO2=8.8 and PO′2=159 Torr (1 Torr=133.322 Pa), was measured as a function of temperature between 150 and 950 °C. For cells with Ag electrodes, a good agreement is found between theoretical and measured emf’s at lower temperatures (ca. 340 °C).
The Enhancement of Formose Formation with 2-Hydroxyacetophenone. A Mechanism Involving Aldol and Retro-aldol Reactions
Authors: Sakai Tomoya , Ishizaki Masahiko , Goto Masafumi 
Published: July 2006

Abstract
The rapid aldol addition of formaldehyde to 2-hydroxyacetophenone (HAP), an efficient accelerator for formose formation, took place to yield addition products of HAP with one and two molecules of formaldehyde at 35 °C in an aqueous 40% methanol mixture of formaldehyde, HAP, and Ca(OH)2. No further addition product with more than two molecules of formaldehyde attached to HAP was detected throughout the reaction. On the contrary, benzaldehyde and benzoic acid were formed, accompanied by formose sugars. The initial molar amount of HAP corresponded to the sum of the compounds substituted with the phenyl group including benzaldehyde and benzoic acid. The retro-aldol reaction of the HAP derivatives is likely to be involved in the overall reaction to yield glycolaldehyde or trioses, which are good accelerators for formose formation.
An Application of Molecular Mechanics Calculations on Thermal Reactions of Ten-membered Ring Sesquiterpenes
Authors: Terada Yukimasa , Yamamura Shosuke 
Published: July 2006

Abstract
Molecular mechanics calculations were successfully carried out to evaluate relative stabilities of each conformation of germacrenes in their ground states and transition states. In the calculation of such a transition state model as shown in Scheme 1, the parameters for partial bonds were taken as mean values of those for a reactant and a product. Thus, the calculation results on each transition state model indicate that the elemenes are formed from the corresponding germacrenes through the most stable transition state (CC), regardless of the most stable conformers in ground state. Calculations were also carried out on ground and transition states of acoragermacrone and isoacoragermacrone, both of which have an α,β-unsaturated carbonyl system. The calculation results on each transition state model indicate that shyobunone (5) and epishyobunone (6) both are formed from acoragermacrone through the corresponding transition states [5 from CC; 6 from C′C′ and C′T] in relative ratio (5/6=87/13) which is in good agreement with that of the experimental result (5/6=84/16). In the case of isoacoragermacrone, molecular mechanics calculations indicate that the preisocalamendiol-type transition state model is more favorable than the models corresponding to the Cope rearrangement products.
Fluoride Salts on Alumina as Reagents for Alkylation of Phenols and Alcohols
Authors: Ando Takashi , Yamawaki Junko , Kawate Takehiko , Sumi Shinjiro , Hanafusa Terukiyo 
Published: July 2006

Abstract
The effectiveness of alkali metal fluorides impregnated on alumina as a reagent for promoting alkylation was optimized with respect to the metal cation, the amount of impregnation, and the reaction solvent. Potassium or caesium fluoride on alumina in acetonitrile or 1,2-dimethoxyethane was concluded to be the best reaction system for general use. O-Alkylation of substituted phenols, primary and secondary alcohols, and a glycol was carried out mostly in good yields under mild conditions with simple experimental procedures.
Restricted Rotation Involving the Tetrahedral Carbon. XLII. Barriers to Rotation and Populations of Rotamers in 9-[2-(Substituted methyl)-1-napthyl]fluorenes
Authors: Saito Ryo , Oki Michinori 
Published: July 2006

Abstract
Rotational barriers in 9-[2-(substituted methyl)-1-naphthyl]fluorenes are found not significantly affected by the substituent on the methyl group, ΔG\eweq’s being ca. 29 kcal/mol at 373 K. Populations of sp- and ap-rotamers at equilibriums show that the sp form is favored to some extent and the results are attributed to entropy factor. OH···π interaction is detected in the ap form of 9-(2-hydroxymethyl-1-naphthyl)fluorene.
The Lowest Triplet State of 2-Methylpyrazine
Authors: Watanabe Takeshi , Shimada Hiroko , Shimada Ryoichi 
Published: July 2006

Abstract
The infrared and Raman spectra of 2-methylpyrazine were studied. An assignment was given for all fundamental vibrations based on the polarization behavior of the spectral bands and on the normal coordinate analysis. The magnetic effect on the phosphorescence lifetime and the time-resolved and polarized phosphorescence spectra of this molecule were investigated at 1.4 K. From the analysis of the phosphorescence, (1) the short lifetime phosphorescence was assigned to the emission arising from the most emissive y″ sublevel, as in the case of pyrazine, (2) the long lifetime phosphorescence was assigned to the emissions arising from the x and z″ sublevels, whose lifetimes were roughly equal to each other and (3) the 0-0 and totally symmetric vibronic bands, and the out-of-plane vibronic bands observed in the long lifetime phosphorescence, were ascribed to the z″ and x sublevel emissions, respectively.
Conformational Characterization of S-Methyl Dithiocarbazate by Infrared Spectra and Vibrational Assignments
Authors: Manogaran Sadasivam , Sathyanarayana Dixit Narayanarao 
Published: July 2006

Abstract
Infrared spectra are recorded for S-methyl dithiocarbazate and its N-deuterated compound in two molecular conformations in the solid state and in solution between 4000 and 30 cm−1. The assignments have been supported from a complete normal coordinate analysis; the conformation sensitive bands of the –CSNHNH2 grouping are discussed. The assignments are compared with those of related molecules to check the internal consistency and to obtain the pattern of the characteristic bands of thiocarbazoyl (–CSNHNH2) group. The magnitudes of the C–N and S–CH3 torsional barriers are estimated from the force constants.
Spectrophotometric Determination of Osmium by Ternary Complex Formation with Thiocyanate and Rhodamine 6G
Authors: Jaya Sambamurthy , Ramakrishna Tiruvesaloor Venkatrama 
Published: July 2006

Abstract
Osmium in trace amounts is determined by use of its reaction with thiocyanate and Rhodamine 6G to form an ion-association complex at pH 3.0. Aided by stabilization with gelatin, measurement of absorbance at 565 nm permits the determination of osmium in the range 0.04–1.2 ppm. The colour system is very stable and provides a molar absorptivity of 6.84×104 l mol−1 cm−1. A few elements interfere and methods are suggested for handling them except ruthenium and rhodium.
A Convenient Synthesis of Linear 2-Methylpyranochromones
Authors: Ahluwalia Vinod Kumar , Jain Anjula , Gupta Ranjna 
Published: July 2006

Abstract
A convenient synthesis of linear 2-methylpyranochromones, viz., spatheliachromen(5-hydroxy-2,2,8-trimethyl-2H,6H-benzo[1,2-b:5,4-b′]dipyran-6-one), O-methylspatheliachromen (5-methoxy-2,2,8-trimethyl-2H,6H-benzo[1,2-b:5,4-b′]dipyran-6-one) (8) and O-methylallopteroxylin (5-methoxy-2,8,8-trimethyl-4H,8H-benzo[1,2-b:3,4-b′]dipyran-4-one) is described by blocking the eighth position of the corresponding 7-propargyl ether derivative 7-(1,1-dimethyl-2-propynyloxy)-8-iodo-5-methoxy-2-methyl-4H-1-benzopyran-4-one with iodine followed by thermal cyclization. The linear pyranochromones 2,2,8-trimethyl-2H,6H-benzo[1,2-b:5,4-b′]dipyran-6-one and 8 are also synthesized starting with the easily available appropriate 3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-7-ols following the steps of Claisen condensation with ethyl acetate, cyclization with ethanolic sulfuric acid followed by dehydrogenation with NBS.
Liquid Crystals of Binary Mixtures. Induction of Nematic Phase by Intermolecular Charge-transfer Interaction and Application of Solid-solution Model
Authors: Iida Yôichi 
Published: July 2006

Abstract
Nematic phase induced by binary mixture consisting of electron donor and acceptor was examined by using modified solid-solution model. The experimental results of Araya and Matsunaga were explained by this approach, and the charge-transfer interaction energy between donor and acceptor in the nematic phase was estimated by analyzing their phase diagrams.