bluuebunny/crossref_metadata_2025 huggingface dataset:
The Photo-induced Radical Rearrangement of 7-Oxocholesteryl Hypoiodite in the Presence of Mercury(II) Oxide and Iodine
Authors: Suginome Hiroshi , Yonebayashi Fumihiro
Published: July 2006

7-Oxocholesteryl hypoiodite in benzene containing mercury(II) oxide and iodine underwent a photo-induced rearrangement to give 5-iodomethyl-A-nor-5ξ-cholestane-3,7-dione and 2-iodo-7-oxo-A-nor-2,3-secocholest-5-en-3-yl formate in low yields, together with cholesta-3,5-dien-7-one without any accompanying 3α,5-epoxy-6-iodo-A-homo-4-oxacholestanes which are common products in the reactions of cholest-5-en-3-ols. The results thus show that the introduction of an oxo group at the C-7 position results in an appreciable change in the products of the reactions of cholest-5-en-3-ols.
Further Studies of the Rate Constant for Chemical Excitation of OH in Shock Waves
Authors: Koike Tohru , Morinaga Kihei
Published: July 2006

Electronically excited OH(2Σ) is formed both by chemical and thermal excitations in the H2-O2 reaction. The OH(2Σ) emission in the partial equilibrium region of the reaction was measured in 1250–3450 K incident shock waves for a mixture, H2/O2/Ar=2/2/96, at starting pressures, 6–30 Torr. The correlation factor between the emission intensity and the concentration of OH(2Σ) was derived in the temperature region above 2800 K where the thermal excitation of OH(2Σ) is dominant. The factor was utilized to estimate the concentration of chemically excited OH(2Σ) and the rate constant of the reaction O+H+M=OH(2Σ)+M was determined as 1013.92±0.17 exp[−(8.3±1.2) kcal/RT)] (cm6 mol−2 s−1).
Highly Selective Carbon-Carbon Bond Forming Reactions Mediated by Chromium(II) Reagents
Authors: Hiyama Tamejiro , Okude Yoshitaka , Kimura Keizo , Nozaki Hitosi
Published: July 2006

A low valent chromium reagent is generated from chromium(III) chloride and a half mol of lithium aluminum hydride in tetrahydrofuran. The reagent behaves similarly to anhydrous chromium(II) chloride, which is commercially available, and reduces allylic halides to produce unisolable allylchromium species which add efficiently to aldehydes or ketones with high degree of stereo- and chemoselectivity. Particularly, high threo selectivity is observed in the reaction of aldehydes and 1-bromo-2-butene and is ascribed to a chair-like six-membered transition state. Simple reduction of allylic and benzylic halides produces biallyls and bibenzyls, while gem-dibromocyclopropanes afford the corresponding allenes in excellent yields.
Stability Constants of Some Chromium(II) Complexes
Authors: Cannon Roderick David , Gholami Mohammad Jan
Published: July 2006

Equilibria between the binuclear complex Cr2(O2CMe)4 and various chelating ligands have been studied spectrophotometrically in acetate buffer media. Combining the results with previous data on the stability of Cr2(O2CMe)4, we obtain formation constants for mononuclear chromium(II) complexes with the following ligands: malonate, logβ2=6.0±0.2; N-methyliminodiacetate, logβ2=12.3±0.5; ethylenediamine-N,N′-diacetate, logK1=9.1±0.2; at T=25 °C, I=1.0 M (1 M=1 mol dm−3) (NaClO4).
Synthesis of Unsubstituted Thia Crown Ethers via Intramolecular Cyclization
Authors: Nakatsuji Yohji , Watanabe Yoshitaka , Okahara Mitsuo
Published: July 2006

A remarkable temperature dependence of the template effect of alkali metal cations was found in the cyclization of thio analogs of penta- or hexaethylene glycols to thia 15-crown-5 or 18-crown-6. The optimum range of the reaction temperature was found to be 80–100 °C.
Regioselective Preparation of 2- and 3-Nitrodibenzofurans by the Direct Nitration of Dibenzofuran
Authors: Keumi Takashi , Yamada Hideyo , Takahashi Hisakazu , Kitajima Hidehiko
Published: July 2006

Nitration of dibenzofuran with nitric acid in trifluoroacetic acid gave 3-nitrodibenzofuran selectively under very mild conditions. In contrary, the Friedel-Crafts type nitration using alkyl nitrates and aluminium chloride in nitromethane gave 2-nitrodibenzofuran as the main product.
Bifunctional Oxidation of Ammonia with Metal Oxide–Pt/Al2O3 Mechanical Mixtures
Authors: Kosaki Yukio , Miyamoto Akira , Murakami Yuichi
Published: July 2006

Selectivity to N2 in the reaction of NH3 with metal oxides has been markedly increased by the addition of Pt/Al2O3 to the metal oxides, whereas the activity of the metal oxides has not been changed. The metal oxides on their own have oxidized NH3 to NO, NO2, and N2O as well as N2, and furthermore, the selectivities in the reaction with metal oxides have depended markedly on the reaction temperature and inlet concentration of NH3 in the pulse. In the oxidation of NH3 with metal oxide–Pt/Al2O3 mechanical mixtures, N2 has been selectively produced irrespective of the reaction temperature and the inlet concentration of NH3 in the pulse. The activity of the mixtures has been shown, on the other hand, to be the same as that of the metal oxides. All of the experimental data have been explained in terms of the following scheme: In the oxidation of NH3 with metal oxide–Pt/Al2O3 mixtures, NH3 is at first oxidized by metal oxides to form NOx(NO, NO2, and N2O) and N2, then the NOx components is transfered through the gas phase from the metal oxides to Pt particles on Al2O3, and finally the NOx. components react with NH3 on Pt particles to form N2 selectively.
Preparation of α-Nitro Olefins from α-Halo Ketoximes
Authors: Sakakibara Tohru , Ikeda Yutaka , Sudoh Rokuro
Published: July 2006

α-Nitro olefins were synthesized from α-haloketones through oximation and subsequent oxidation with trifluoroperacetic acid.
Bis(p-methoxyphenyl) Selenoxide as a Mild and Selective Oxidizing Agent
Authors: Ogura Fumio , Yamaguchi Hachiro , Otsubo Tetsuo , Tanaka Hiroyuki
Published: July 2006

The title compound oxidized thiols to disulfides, sulfides to sulfoxides, hydroquinone or catechol to benzoquinones, and phosphine to phosphine oxide in high yields under very mild conditions. In addition, it functioned as a useful reagent for the syntheses of 1,2,4-thiadiazole derivatives from thioureas or thioamides.
Mechanochemical Reactions at High Pressures. III. Reactions of Acrylamide–Methacrylamide and Acrylamide–Propionamide Solid Solutions
Authors: Okuri Yasuhiro , Ogo Yoshiaki
Published: July 2006

The mechanochemical behavior of acrylamide–methacrylamide (AA–MAA) and acrylamide–propionamide (AA–PA) solid solutions was investigated at room temperature and at static pressures of up to 15 kbar. The AA–MAA solid solution was copolymerized under the experimental conditions. On the other hand, the reaction product of AA–PA solid solution was an amorphous homopolymer of polyacrylamide. That is, the mechanochemical reaction of AA–PA solid solution proceeded only in the acrylamide area by a free radical mechanism. The mechanical behavior of both solid solutions was also discussed.
Heterogeneous Photocatalytic Reactions on Semiconductor Materials. III. Effect of pH and Cu2+ Ions on the Photo-Fenton Type Reaction
Authors: Fujihira Masamichi , Satoh Yoshiharu , Osa Tetsuo
Published: July 2006

The effect of pH and Cu2+ ions on the heterogeneous photocatalytic oxidation of toluenes by H2O2 formed from dissolved O2 in the presence of illuminated TiO2 powders, i.e. “the photo-Fenton type reaction,” was investigated. At low and high pH, a total amount of products increased drastically compared with that of the additive free system (pH 7). In the acidic region (aqueous H2SO4), side-chain oxidation prevailed over cresol formation and benzaldehyde was formed quite selectively at pH 1. Oxidation of the side chain in preference to hydroxylation of aromatic ring was also observed in the alkaline region (aqueous NaOH). By adding Cu2+ ion to the aqueous H2SO4 (pH 1 and 2), the yield of benzaldehyde increased further and cresols, benzyl alcohol, and bibenzyl were formed newly in high yields. At high Cu2+ concentrations (pH 2), the cresol formation in preference to the side-chain oxidation was attained. The observation was in good agreement with the Fenton reaction reported in which Cu2+ and Fe3+ ions are added as oxidants for the intermediate products, such as hydroxycyclohexadienyl and benzyl radicals, formed by HO· attack to toluene. Cu2+ ion was more preferable to Fe3+ ion as the oxidant, since “short circuiting” by Cu2+ due to the reversible redox reaction at semiconductor particles was much lower than that by Fe3+. By adding a large amount of Cl− ions to the Cu2+–H2SO4 aqueous system, no oxidation of toluene resulted.
Preparation and Physical Properties of EuC2 and Its Solid Solutions, RxEu1−xC2 (R=La and Gd)
Authors: Sakai Tetsuo , Adachi Gin-ya , Yoshida Takeshi , Ueno Shin-ya , Shiokawa Jiro
Published: July 2006

A cubic-tetragonal phase transformation of EuC2 was observed at 623 K. The phase transition temperatures of metal dicarbides (MC2) were discussed in terms of the band structure proposed by previous authors. The compound EuC2 was a ferromagnet with a zero field curie temperature of 20 K, which was close to the value expected from the Curie temperature vs. nearest neighbor Eu–Eu distance relation for the Eu chalcogenides. The solid solutions, LaxEu1−xC2, became ferromagnetic at low temperatures over the whole composition range, while the solid solutions, GdxEu1−xC2, have continuously changed the kind of magnetic order from ferromagnetic to antiferromagnetic. All the effective moments obtained for RxEu1−xC2 were in good agreement with the theoretical values of Eu2+ and R3+ contained. The electrical resistivities of EuC2 and its solid solutions had a sharp peak near the Curie temperature. When magnetic field was applied, the peak became broader and shifted to higher temperature.
Protolytic Kinetics of Some Pyridine Derivatives in Non-buffered Aqueous Solution
Authors: Ando Isao , Ujimoto Kikujiro , Kurihara Hirondo
Published: July 2006

The deprotonation rates of the conjugate acids of 2,2′-bipyridine and pyridine, and the protonation rates of 2-aminopyridine and 4-aminopyridine were measured in non-buffered aqueous solution by means of a stopped-flow pH jump method. These pyridine derivatives showed quite slow protolytic behavior, similar to that of 1,10-phenanthroline and cyclopentadienes: the deprotonation rate constants of conjugate acids of 2,2′-bipyridine and pyridine are (4.8±0.7)×10−1 and (6.0±2.2)×10−2 s−1, respectively. The deprotonation rates of barbituric acid and acetylcyclopentadiene as authentic samples were also measured. Their deprotonation rate constants are in good agreement with the literature values, this demonstrates the validity and the applicability of the stopped-flow pH jump method. This method is superior to the NMR method for the determination of the protontransfer rates of azaaromatic compounds.
Highly Aggregated State of the Dye with the Detergent in the Premicellar Region as Revealed by Resonance Raman Spectra
Authors: Katsumata Masaaki , Kasatani Kazuo , Kawasaki Masahiro , Sato Hiroyasu
Published: July 2006

Resonance Raman spectra of 3,3′-diethylthiacarbocyanine iodide–sodium dodecyl sulfate (SDS) system are characterized by [SDS]-dependent change of band intensities. The change was much larger than that accompanied with the shift of monomer-dimer equilibrium in the aqueous solution. The spectra for [SDS]<<critical micelle concentration (cmc) resemble that of the dye in the solid state, indicating the highly-aggregated state of the dye caused by the interaction with the detergent.
Characterization of Prussian Blue Analogs of the Type M3[Fe(CN)5CO]2·xH2O
Authors: Inoue Hidenari , Kawai Takashi , Nagao Masaki , Yanagisawa Saburo
Published: July 2006

A series of compounds of the type M3[Fe(CN)5CO]2·xH2O (M=Mn, Co, Ni, Cu, and Zn) have been studied by means of the X-ray diffraction powder patterns, magnetic measurements, infrared, electronic, and M\ddotossbauer spectra. Three compounds M3[Fe(CN)5CO]2·xH2O (M=Mn, Co, and Ni) crystallize in the face-centered cubic system. Copper compound Cu3[Fe(CN)5CO]2·18.5H2O belongs to the tetragonal system, zinc compound Zn3[Fe(CN)5CO]2·13.5H2O being amorphous. The structure of these compounds is described as a three-dimensional framework of two octahedral coordination units FeC6 in the low spin state and MN10⁄3O8⁄3 in the high spin state. The back donation in the Fe(CN)5CO3− moiety is enhanced by the bridge formation through CN− and CO ligands, i.e. upon the formation of M3[Fe(CN)5CO]2·xH2O from the corresponding sodium salt.
Crystallographic Data for New Phases in the CaSO3–H2O System
Authors: Arai Yasuo , Yasue Tamotsu , Nagata Norifumi , Shiino Hiroaki
Published: July 2006

Among the three modifications of calcium sulfite hemihydrate, two of them, hexagonal β-CaSO3·1/2H2O with a rhombohedral lattice and γ-CaSO3·1/2H2O with a simple triangular hexagonal lattice, were found in the authors’ recent work. By heating α- and/or γ-hemihydrate at 330–360 °C in a nitrogen atmosphere, the orthorhombic anhydrate α-CaSO3 was formed, with lattice constants of 6.472, 15.93, and 23.44 Å for a, b, and c respectively, while the body-centered tetragonal anhydrate β-CaSO3, with lattice constants of 15.68 and 19.44 Å for a and c respectively, was formed by heating the β-hemihydrate. The dehydration of three hemihydrates and the hydration of two anhydrates were discussed. The phase relationships in the CaSO3–H2O system were summarized as follows:

α-CaSO3·1⁄2H2O\oversetDehydration (360°C)\undersetHydration(30°C)\ightleftarrowsα-CaSO3+1⁄2H2O;

β-CaSO3·1⁄2H2O\oversetDehydration (360°C)\undersetHydration (30°C)\ightleftarrowsβ-CaSO3+1⁄2H2O;

γ-CaSO3·1⁄2H2O\xrightarrowDehydration (330°C)α-CaSO2+1⁄2H2O;

γ-CaSO3·1⁄2H2O\xrightarrowTransformation (in water at 20°C)

β-CaSO3·1⁄2H2OO\xrightarrowTransformation (in water at 20°C)α-CaSO3·1⁄2H2O.
An Ab Initio MO Calculation for the Bonding Structure of [Ni(CN)4]2−
Authors: Sano Mitsuru , Kashiwagi Hiroshi , Yamatera Hideo
Published: July 2006

An ab initio MO calculation of [Ni(CN)4]2− has been carried out with a double zeta basis set. The nickel-cyanide interactions are discussed and the electronic change occurring on the coordination of CN− to Ni2+ is shown by using the MO contours and the electron-density difference map. The map shows σ donation from the cyanide orbitals and π back-donation from the metal dxy orbital.
Solubility Isotherms of Systems Containing Optically Active Tris(ethylenediamine)cobalt(III) Ion. III. Quaternary System, (Λ-[Co(en)3]3+, Δ-[Co(en)3]3+, H+)–(R,R)-C4H4O62−–H2O, at 25 °C
Authors: Fuyuhiro Akira , Yamanari Kazuaki , Shimura Yoichi
Published: July 2006

A part of quaternary solubility isotherm, (Λ-[Co(en)3]3+, Δ-[Co(en)3]3+, H+)–(R,R)-C4H4O62−–H2O, CH+≤C(R,R)-C4H4O62−, was determined at 25 °C. It was found that three double salts Λ- and Δ[Co(en)3](d-C4H5O6)· (d-C4H4O6)·nH2O and Λ-[Co(en)3]0.48 ·Δ-[Co(en)3]0.52(d-C4H4O6)1.5·5H2O exist, three invariant points appearing. The yield for optical resolution of [Co(en)3]3+ found to be constant regardless of [H+]. The existence of complete ternary system containing double salts, Λ-[Co(en)3](d-C4H5O6)(d-C4H4O6)–Δ-[Co(en)3](d-C4H5O6)(d-C4H4O6)–H2O, was found and the solubilities of Λ- and Δ-[Co(en)3](d-C4H5O6)(d-C4H4O6) were measured at 5–65 °C.
Cation Exchange Separation of Metal Ions Using HF–H3BO3 Media
Authors: Adachi Takeo
Published: July 2006

Using hydrofluoric–boric acid media, a new cation exchange method for the mutual separation of metals which form stable fluoride complexes has been developed. The addition of boric acid to a hydrofluoric acid solution reduces the free fluoride ion concentration to about one hundredth because of the formation of fluoroboric acid. This reduction of the free fluoride ion concentration makes it easy to control the formation of metal fluoride complexes, favoring their separation. As the fluoroboric acid has a buffer action relating to the fluoride ion concentration, the distribution coefficients of metal ions are not affected by the increase in the concentrations of metal ions, even at a low concentration of fluoride ions in the solution. By the use of hydrofluoric–boric acid media, such metals as zirconium, titanium, aluminium, and uranium can be separated from each other. The distribution coefficients of eighteen metals were investigated both in hydrofluoric acid and hydrofluoric–boric acid solutions.
Preparation and Physicochemical Properties of New Linear μ-Oxo Bridged Ruthenium(IV) and Osmium(IV) Porphyrin Dimers
Authors: Sugimoto Hiroshi , Higashi Teruaki , Mori Masayasu , Nagano Motoi , Yoshida Zen-ichi , Ogoshi Hisanobu
Published: July 2006

μ-Oxo-bis[(hydroxo)(octaethylporphyrinato)ruthenium(IV)] was prepared by the oxidation of (carbonyl)(octaethylporphyrinato)ruthenium(II) with t-butyl hydroperoxide in good yield. Facile replacement of the hydroxyl group with various anions afforded μ-oxo dimer complexes formulated as [{RuIV(oep)X}2O] (X=Cl, Br, and OCOCH3). The same type of osmium complexes, [{OsIV(oep)(OCH3)}O], {[OsIV(oep)(OCH3)}O{OsIV(oep)(OH)}], and [{OsIV(oep)(OH)}2O] were obtained from the air oxidation product of (carbonyl)(methanol)(octaethylporphyrinato)osmium(II) in the presence of 2,3-dimethylindole. These complexes are diamagnetic. The 1H NMR data are in conformity with the linear oxo-bridged dimer structure which was proved by X-ray crystallography with [{RuIV(oep)(OH)}2O]. The redox potentials were measured by the cyclic voltammetry. These complexes showed three distinct quasi-reversible redox couples assignable to metalII/ metalIII, metalIII/metalIV, and porphyrin ligand oxidation, respectively. Significantly lower redox values and anomalous spectral features indicate a strong pπ-dπ interaction between the bridging oxygen atom and the two quadrivalent metal ions.
A Kinetic Study on Reduction of 9,9′-Bifluorenylidene by Sodium Isopropoxide
Authors: Kajigaeshi Shoji , Fujisaki Shizuo , Nakashige Yasuhiko , Murakami Sadaaki
Published: July 2006

The kinetics and mechanism of reduction of 9,9′-bifluorenylidene (1) by sodium isopropoxide (2) in isopropyl alcohol to yield 9,9′-bifluorenyl (3) were investigated spectrophotometrically. The kinetic data suggest that the reduction proceeds autocatalytically, the reduction product 3 acting as the catalyst. It was found that

1\xrightarrow[2]k13 (1) 1+3\xrightarrow[2]k23+3 (2)

Reactions 1 and 2 are of the first order with respect to 1, but that the former is of the third order with respect to 2, whereas the latter is of the first. The fourth- and third-order rate constants, k1 and k2, for Reactions 1 and 2 were determined to be 3.0×10−5 dm9 mol−3 s−1 and 1.1×103 dm6 mol−2 s−1, respectively, at 130 °C. Probable mechanisms for Reactions 1 and 2 have been offered on the basis of the reaction order for each molecular species involved.
Hydrolysis of Carbohydrates in the Presence of a Reversed Micelle. III. Hydrolysis of Dextrin in Benzene
Authors: Arai Kenichiro , Ogiwara Yoshitaka
Published: July 2006

The secondary solubilization of dextrin in a dodecylbenzenesulfonic acid (DBSH) reversed micelle in benzene containing a small amount of water was examined; a perfectly clear solution was obtained. The solution showed a CMC of DBSH, estimated by the method of Methylene Blue methachromasis, just like that of sucrose-containing similar reversed-micelle system. The hydrolysis of the dextrin in the system was investigated; the maximum rate enhancement of 285-fold was obtained on the basis of the reaction in DBSH aqueous solution. The CMC and the reaction rate showed changes similar to those in the case of sucrose-containing similar reversed-micelle system with changing the amount of water solubilized, but they showed different changes with changing the concentration of the substrate. These different changes were supposed to result from the differences in the molecular weights of the substrates. These results suggested that the rate enhancement mechanism due to solvent effect and micelle effect which was proposed for the hydrolysis of sucrose in the presence of a DBSH reversed micelle operates in the hydrolysis of the high molecular weight substrate such as dextrin.
Photooxygenation Reaction and Chemiluminescence of (Arylmethylenehydrazono)triphenylphosphoranes. Possible Generation of Phospha-1,2-dioxetanes
Authors: Suzuki Nobutaka , Sano Kaniti , Wakatsuki Satoshi , Izawa Yasuji
Published: July 2006

Photosensitized oxygenation of (benzylidenehydrazono)-, (diphenylmethylenehydrazono)-, (9-fluorenylidenehydrazono)-, (9-xanthenylidenehydrazono)-, and (10-methyl-9,10-dihydroacridin-9-ylidenehydrazono)triphenylphosphoranes at −78 °C gave the corresponding carbonyl compounds and triphenylphosphine oxide and also gave light emission upon warming-up to room temperature.
Furan Derivatives. IV. On the Effects of Substituents in the Syntheses of 4,5-Dihydro-3H-naphtho[1,8-bc]furans
Authors: Horaguchi Sakaaki , Hara Mamoru , Suzuki Tsuneo
Published: July 2006

The reaction of (8-oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetic acids with acetic anhydride and sodium acetate give a mixture of 4,5-dihydro-3H-naphtho[1,8-bc]furans and lactones. The relative yields of 4,5-dihydro-3H-naphtho[1,8-bc]furans and lactones varied according to kinds of substituents on the benzene ring of (8-oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetic acids. Substituents which make the methylene group approach closer to the carbony carbon atom of (8-oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetic acids by a steric effect seem to favor the production of 4,5-dihydro-3H-naphtho[1,8-bc]furans. On the other hand, substituents which make the methylene group separate from the carbonyl carbon atom seem to favor the production of lactones. An electron-withdrawing chlorine atom on the benzene ring of (8-oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetic acids also favors the production of 4,5-dihydro-3H-naphtho[1,8-bc]furans.
Functionalization of trans-Decalin. V. A Synthesis of (±)-Nootkatone and (±)-Valencene from 4β,4aβ-Dimethyl-Δ6,7-octalin-1-one Ethylene Acetal
Authors: Torii Sigeru , Inokuchi Tsutomu , Handa Ko
Published: July 2006

A synthesis of (±)-nootkatone (1) and (±)-valencene (18) starting from 4β,4aβ-dimethyl-Δ6,7-octalin-1-one ethylene acetal (2) is described. Epoxidation of the double bond of 2 followed by regiospecific reduction of the oxirane ring at the C-6 position gave the corresponding C-7 alcohol 4. Oxidation of 4 and subsequent methoxycarbonylation at the C-6 position afforded methyl 1,1-ethylenedioxy-4β,4aβ-dimethyl-7-oxodecalin-6-carboxylate (6) in good yield. The keto ester 6 was converted to methyl 1,1-ethylenedioxy-4β,4aβ-dimethyldecalin-6α-carboxylate (10b) by the reduction with NaBH4 followed by dehydration and subsequent hydrogenation over PtO2 and epimerization of the 6β-methoxycarbonyl group with MeONa in MeOH. Deacetalization of 10b followed by reduction and dehydration afforded methyl 4β,4aβ-dimethyl-Δ1(8a)-octalin-6α-carboxylate (15). The conversion of 15 into (±)-18 was carried out directly by the reaction with salt-free methylenetriphenylphosphorane in refluxing tetrahydrofuran (76%) or by hydrolysis of 15 followed by methylation with MeLi, and subsequent Wittig reaction (60%). The allylic oxidation of (±)-18 with CrO3·(pyridine)2 complex gave the desired (±)-1, smoothly.
Synthesis and Stereochemistry of Hypusine, a New Amino Acid in Bovine Brain.
Authors: Shiba Tetsuo , Akiyama Hitoshi , Umeda Isao , Okada Satoshi , Wakamiya Tateaki
Published: July 2006

Hypusine, a new basic amino acid occurring in the homogenate of bovine brain tissue, was synthesized to determine the absolute structure. Nα-Benzyloxycarbonyl-l-lysine benzyl ester was coupled with (S)- or (R)-4-benzyloxycarbonylamino-1-bromo-2-butanol derived from l- or d-malic acid, respectively. The products were deprotected by catalytic hydrogenation. One of the synthetic compounds, i.e., (2S,9R)-2,11-diamino-9-hydroxy-7-azaundecanoic acid, was completely identical with natural hypusine in all respects.
Preparation of Homologs of l-2-Amino-5-(p-methoxyphenyl)pentanoic Acid
Authors: Kosui Nobuo , Waki Michinori , Kato Tetsuo , Izumiya Nobuo
Published: July 2006

Lower and higher homologs, l-2-amino-4-(p-methoxyphenyl)butanoic acid (l-Amb) and l-2-amino-6-(p-methoxyphenyl)hexanoic acid (l-Amh), of l-2-amino-5-(p-methoxyphenyl)pentanoic acid were prepared by optical resolution of N-acetyl-Dl-Amb and of N-acetyl-Dl-Amh with Aspergillus acylase. N-Acetyl-Dl-Amb or N-acetyl-Dl-Amh was synthesized from [2-(p-methoxyphenyl)ethyl or butyl](acetamido)malonic acid by heating with p-xylene.
The Configurations of Benzylmethyl(o- or p-tolyl)silylmethylamine and the Stereochemistry of the Reactions of Benzylmethylmethoxyphenylsilane with Some Organometallic Agents
Authors: Terunuma Daiyo , Senda Kazuhisa , Sanazawa Masato , Nohira Hiroyuki
Published: July 2006

Optically active α-amino organosilanes such as benzylmethyl(o- or p-tolyl)silylmethylamine were converted into benzylmethylphenyl(o- or p-tolyl)silane, of which the configurations had been known. From these observations, it was found that (+)- and (−)-benzylmethyl(o- or p-tolyl)silylmethylamine has S and R configuration respectively. Furthermore, the stereochemistry of the reaction of benzylmethyl(methoxy)phenylsilane with some organometallic agents was investigated.
Branched-chain Sugars. XXVIII. Synthesis of 2-C-Methyl-l-glyceraldehyde, 2-C-Methyl-d-erythrose, and 3-C-Methyl-l-erythrose Derivatives
Authors: Yoshimura Juji , Hara Kazutoshi , Yamaura Masanori , Mikami Kazutoshi , Hashimoto Hironobu
Published: July 2006

As synthons for the synthesis of bicyclomycin, the title compounds were derived from 1,2:5,6-di-O-isopropylidene-3-C-methyl-α-d-allofuranose by the descendent method.
Solvent Effects on the Isomerization of 1-Pentene Catalyzed by Cationic Platinum Complexes
Authors: Kanai Hiroyoshi , Hirako Osamu
Published: July 2006

The isomerization of 1-pentene with [PtH(PPh3)3]X (X=SO4H, ClO4) occurred only in ethers. The decrease in the concentrations of 1-pentene and the platinum complexes leads to high cis-selectivity.
Thermolysis of 6-Hydroxyimino-1,3,5-tri-t-butyl-5-methyl-1,3-cyclohexadiene
Authors: Okazaki Renji , Watanabe Masako , Inamoto Naoki
Published: July 2006

Mechanism of the thermolysis of the titile compound has been proposed, which begins with a homolytic cleavage leading to t-butyl radical and 2,4-di-t-butyl-6-methyl-1-nitrosobenzene. The reaction of the nitrosobenzene with t-butyl radical generated from photolysis of 2,2′-dimethyl-2,2′-azopropane is also described.
The Influence of Additives on the Decomposition of an Alkaline Manganate(VII) Solution
Authors: Narita Eiichi , Hashimoto Tatsuhiko , Yoshida Sakae , Okabe Taijiro
Published: July 2006

The decomposition of manganate(VII) in an alkaline solution was significantly enhanced by the addition of hydrous manganese(IV) oxide or metal ions, such as Ni(II) and Co(II). On the other hand, the inhibitive effect of the tellurate(VI) ion on the decomposition was found even in the presence of the additives described above.
The Crystal Structure of Bis(methyl 3-benzylidenedithiocarbazato)nickel(II)
Authors: Uechi Tetsuo , Oniki Takayuki
Published: July 2006

The title compound crystallizes in the monoclinic space group P21/a with two molecules in a unit cell of dimensions; a=21.479(5), b=4.2092(6), c=14.257(3) Å, and β=129.53(2)°. The structure was refined by block-diagonal least-squares procedures to give a final R value of 0.032 for 1693 reflections with I>3σ(I) collected on a four-circle X-ray diffractometer. The complex consists of two methyl 3-benzylidenethiocarbazate groups, each bound to the central Ni atom through the thiol S atom and the hydrazine N atom, to yield a five-membered chelate ring. The NiN2S2 moiety is trans square-planar, with Ni–S and Ni–N bond distances of 2.1767(9) and 1.927(3) Å respectively. An examination of the bond distances and the planarity of the molecule revealed a delocalization of the π electrons over the chelate ring. The intra-molecular contact of S···H is 2.35(4) Å, which indicates a definite C–H···S interaction or hydrogen bonding.
Polymerization of Silicic Acid Adsorbed on Aluminium Hydroxide
Authors: Yokoyama Takushi , Nakamura Osamu , Tarutani Toshikazu
Published: July 2006

Factors controlling the absorption of silicic acid on aluminium hydroxide from aqueous solution and the polymerization of adsorbed silicic acid were studied. Measurements included the amount of silicic acid adsorbed on aluminium hydroxide, the amount and size distribution of the polysilicic acid formed, and the differential thermal analysis curve of aluminium hydroxide which had adsorbed silicic acid. The adsorption and the polymerization of silicic acid are affected by pH, the relative amounts of silicic acid and aluminium hydroxide, the reaction time between monosilicic acid and aluminium hydroxide, and the formation of amorphous aluminosilicate. The amount of adsorbed silicic acid and the rate of its polymerization are maximum at pH 9.0–9.5. A part of adsorbed monosilicic acid reacts with aluminium hydroxide to form an aluminosilicate. In an early stage of the polymerization of the adsorbed silicic acid, the polymerization mainly proceeds by the reactions between monosilicic acids and between monosilicic and polysilicic acids; the particle sizes of polysilicic acids gradually increase with time. When the polymer particles grow large enough to touch neighboring polymers, the growth rate of polymer particles becomes faster due to the polymer-polymer reactions.
Kinetic Study on Conformational Changes of Poly(l-lysine) in Sodium Alkyl Sulfate Solutions. Effects of Surfactant Chain Length and Added NaCl
Authors: Takeda Kunio , Iba Akira , Shirahama Keishiro
Published: July 2006

The conformational changes of poly(l-lysine) (PLL) were observed in alkyl sulfate solutions by a circular dichroic method. PLL forms a β-structure in sodium dodecyl sulfate solution with an apparent first-order rate constant of 3.0×10−2 s−1 (20 °C). In sodium octyl sulfate (SOS) solution, PLL assumes the α-helix within a certain concentration range of the surfactant, above which the β-structure is favored. The rate of coil to β-structure transition slows down with increase in hydrophobic interaction between surfactants and PLL. The presence of sodium ions decreases the rate of coil to α-helix transition by about two orders of magnitude (2.0×10−1 s−1 salt free to 3.0×10−3 s−1 in the presence of 2.0×10−2 mol/dm3 NaCl at 20 °C). These phenomena are explained in terms of a rearrangement process of bound surfactants adjusting for a free energy minimum; a stronger binding force brings about a slower rearrangement rate.
Prediction of Adsorbability of Organic Compounds from Aqueous Solution on Activated Carbon by Means of the Linear Free-energy Relationship
Authors: Abe Ikuo , Hayashi Katsumi , Kitagawa Mutsuo , Hirashima Tsuneaki
Published: July 2006

A method is presented for predicting the adsorbability of a wide variety of organic compounds from aqueous solution onto an activated carbon. The method, which is based on the linear free-energy relationship, requires only the solute’s molecular refraction and the number of hydrophilic functional groups. The molecular refraction represents the free energy contribution by the solute-adsorbent interaction and the number of hydrophilic functional groups represents that by the solute-solvent interaction.
Cyclopropanation of Electron-deficient Olefins with Dibromomethane by Ni(0) Complexes and Zinc
Authors: Kanai Hiroyoshi , Hiraki Nobuyuki , Iida Shigeki
Published: July 2006

A new method for the synthesis of cyclopropane derivatives is described. It involves treatment of electrondeficient olefins with dibromomethane in the presence of Ni(0) complex/zinc/Lewis acid (or alkali halide) systems. Ni(PPh3)4/Zn/ZnBr2 system was effective for the cyclopropanation of methyl acrylate and acrylonitrile, but was ineffective for that of methyl vinyl ketone and acrylaldehyde. Ni(COD)2/Zn/NaI system was applicable to the cyclopropanation of methyl vinyl ketone as well as to that of methyl acrylate and acrylonitrile. Alternative catalytic systems which were easy to handle were exploited, involving in situ generated Ni(0) complexes prepared from NiBr2(PPh3)2 and zinc, or nickel bromide, sodium iodide, zinc, and an olefin. Catalytic amounts of nickel compounds are sufficient for the cyclopropanation of methyl acrylate, acrylonitrile, and methyl vinyl ketone, but a 1 : 2 nickel : acrylaldehyde mole ratio results in the best yield. A mechanism is proposed which involves metallacyclobutane as an intermediate.
Metalloenzyme Models. Divalent Metal Ion Catalyzed Hydrolysis of p-Nitrophenyl Picolinate in the Presence of Imidazoles and Pyridines Having Hydroxyl Groups in Their Side Chains
Authors: Ogino Kenji , Shindo Katsuhiko , Minami Tooru , Tagaki Waichiro , Eiki Toshio
Published: July 2006

Rate constants for hydrolysis of p-nitrophenyl picolinate at 25 °C in the pH range 6.5–8.5 were measured in the absence and presence of divalent metal ions (Ni(II), Zn(II), Co(II), Ca, Mg) and substituted imidazoles or pyridines as ligands having alcoholic hydroxyl groups in their side chains. In the presence of either metal ion or ligand, the rate is slow and the pseudo-first-order rate constant (kobsd) increases linearly in a first-order manner with respect to the concentration of metal ion or ligand until it gives the second-order rate constant, kM or kL, respectively. In the presence of both a metal ion (Ni(II) or Zn(II)) and a ligand, rate increase is remarkable for some ligands and the increase in kobsd values constructs saturation curves with respect to increase in either metal ion or ligand concentration. The saturation curves were analyzed based upon rate equations formulated by assuming the formation of 1 : 1 complex of metal ion and ligands as the catalyst, leading to evaluation of the association constant K for complexes and the second-order rate constant kc for the reaction of complex with substrate. Values of kobsd, kc, and K are dependent greatly upon the structure of ligands and pH. The ligands complexed with Zn(II) ion appear to be simple but highly active models of hydrolytic metalloenzymes.
Mechanism for the Oxidative Cleavage of Electron-deficient Acetylenes with Alkaline Hydrogen Peroxide
Authors: Sawaki Yasuhiko , Inoue Hiroshi , Ogata Yoshiro
Published: July 2006

4-Phenyl-3-butyn-2-one (1a) was effectively cleaved by alkaline hydrogen peroxide to afford benzoic and acetic acids. The rate ratio for the addition of HOO− and HO− to 1a resulted in kHOO−/kHO−=1400, which is comparable to that of benzylideneacetone. The major reaction of the cleavage proceeds via benzoylacetone. As a minor pathway, α-keto oxirene intermediate is formed and rearranges only to α-benzoylpropionate in a different way from the corresponding diketo carbene. α-Keto esters are found to be converted by HOO− to α-alkoxy ketones via a novel oxidative substitution of ester group. Methyl phenylpropiolate is oxidized by HOO− similarly as 1a. The mechanism is discussed on the basis of oxirene intermediate inconvertible to keto carbene.
Solution Conformation of Cyclic Dipeptides Having Aliphatic Side Chains
Authors: Tanihara Masao , Hiza Tae , Imanishi Yukio , Higashimura Toshinobu
Published: July 2006

Cyclic dipeptides having aliphatic side chains, cyclo(l-Val)2, cyclo(l-Val–d-Val), cyclo(l-Leu)2, and cyclo(l-Leu–d-Leu) were synthesized and their conformation in solution was investigated by circular dichroism (CD) and proton nuclear magnetic resonance (1H NMR) spectroscopy. 1H NMR spectra in (CD3)2SO of cyclo(l-Val–d-Val) and cyclo(l-Leu–d-Leu) indicated that the diketopiperazine ring of these trans cyclic dipeptides takes a planar or a chair conformation and the molecules take a center-symmetric conformation. 1H NMR spectra in (CD3)2SO and CD spectra in CH3OH and H2O of cyclo(l-Val)2 and cyclo(l-Leu)2 indicated that the conformation of these cis cyclic dipeptides is planar-axial and flagpole-boat-type respectively. It is suggested that cis cyclic dipeptides having aliphatic side chains take such conformations in polar solvents because of the stabilization by attractive forces between aliphatic side chains.
Solution Conformation of cyclo(–l-Cys(S-Acm)–d-Leu–l-His–l-Cys(S-Acm)–d-Leu–l-His–) and Interaction with Cu(II)
Authors: Kodaka Masato , Shimizu Toru , Hatano Masahiro
Published: July 2006

Proton NMR spectra of a cyclic peptide, cyclo-(S-acetarnidoinethyl-l-cysteinyl)-d-leucyl-l-histidyl-(S-acetamidomethyl-l-cysteinyl)-d-leucyl-l-histidyl, were measured and analyzed in order to investigate its conformation and its interaction with Cu(II). A linear peptide, [N-(t-butoxycarbonyl)-S-acetamidomethyl-l-cysteinyl]-d-leucyl-l-histidyl-(S-acetamidomethyl-l-cysteinyl)-d-leucyl-l-histidine methyl ester, was also investigated for comparison. It was strongly suggested that the cyclic hexapeptide forms transannular hydrogen bonds between the cysteine residue peptide bonds and thus two β-turns exist in the d-leucyl-l-histidyl sequences. This finding is particularly noteworthy because the present cyclic peptide has no prolines which are frequently seen in β-turn structures of proteins, naturally occurring peptides or synthetic peptides and because the cyclic peptide we studied is composed of amino acids all bearing the large side chains which seemed likely to prevent β-turn formation due to their steric hindrance. The interactions of the cyclic peptide and the linear peptide with Cu(II) were also studied by observing 1H NMR spectral changes on addition of CuCl2. It was suggested that the imidazolyl groups in the peptides are directly coordinated to Cu(II).
Phosphinyl and Phosphinothioyl Amino Acids and Peptides. VII. The Use of the Dimethylphosphinothioyl Group as a Thiol-protecting Group of Cysteine
Authors: Ueki Masaaki , Shinozaki Kozo
Published: July 2006

The use of the dimethylphosphinothioyl (Mpt) group for the protection of the thiol function in the cysteine side-chain was studied. N,S-Bis(Mpt)-l-cysteine was obtained directly by means of a Schotten-Baumann-type reaction of Mpt–Cl with l-cysteine. The S–Mpt group was stable under acidic conditions, except for HBr in acetic acid, and it could be removed by treatment with AgNO3 or Hg(OAc)2 in an aqueous medium. Glutathione was synthesized by utilizing the new S-protecting group.
Bromination of Biphenylene Derivatives Having an Electron-releasing Substituent. A Preferential Formation of Benzocyclooctene Derivatives
Authors: Kidokoro Hiroto , Saito Yuko , Sato Masaru , Ebine Seiji , Sato Sadao , Hata Tadashi , Tamura Chihiro
Published: July 2006

3-Substituted 2-bromobiphenylenes were brominated to give benzocyclooctene or 7(8H)-benzocyclooctenone derivatives, but not biphenyl derivatives. The structure of 5,8,10-tribromo-7(8H)-benzocyclooctenone was determined by X-ray diffraction analysis.
Effect of Lattice Anions on the Racemization of Optically Active Metal Chelate Salts in the Solid State. 2. [Co(phen)3]X3, [Co(phen)2(en)]X3, and [Co(phen)(en)2]X3, Where X−=Cl−, Br−, or I−
Authors: Fujiwara Terufumi
Published: July 2006

The kinetics of racemization of the anhydrous complexes (−)-[Co(phen)3]X3, (+)-[Co(phen)2(en)]X3, and (−)-[Co(phen)(en)2]X3, where phen=1,10-phenanthroline, en=ethylenediamine, and X−=Cl−, Br−, or I−, have been examined in the solid state. A rapid initial loss of optical activity and a subsequent first-order racemization were observed for the complex salts. Enthalpies and entropies of activation, ΔH\eweq and ΔS\eweq, were evaluated for the first-order process of [Co(phen)3]X3 and [Co(phen)2(en)]X3. It was found that for [Co(phen)3]X3 the chloride salt racemizes more rapidly than the bromide salt and that ΔH\eweq and ΔS\eweq, decrease with the lattice anion in the order X−=Br−>Cl−. On the other hand, the reverse sequence in ΔH\eweq and ΔS\eweq, X−=Br−Br−>Cl−. These anion effects for the series were successfully interpreted in terms of the chemical interactions due to donicity and hydrogen bonding ability of anions, but not in terms of the physical factor, lattice energy. Thermal decomposition studies of the complexes lend support to the interpretation of the racemization kinetic data.
Studies on Salt Hydrate for Latent Heat Storage, II. Eutectic Mixture of Pseudo-binary System CH3CO2Na·3H2O–CO(NH2)2
Authors: Wada Takahiro , Kimura Fumiko , Yamamoto Ryoichi
Published: July 2006

With a view of developing latent heat storage materials, mixtures of pseudo-binary system, CH3CO2Na·3H2O–CO(NH2)2 (sodium acetate trihydrate–urea) were subjected to differentital scanning calorimetry, and the partial phase diagram for ternary system CH3CO2Na–CO(NH2)2–H2O at ambient pressure was constructed. The eutectic mixture, containing 0.6 mass fraction of CH3CO2Na·3H2O and 0.4 mass fraction of CO(NH2)2, melts congruently at 31.5 °C with a heat of fusion of 226 J/g, which is larger than the heat of fusion of CaCl2·6H2O, 180 J⁄g. Thus, mixtures of system CH3CO2Na·3H2O–CO(NH2)2 are promising for solar energy storage.
Synthesis of the 1,2,4-Triazolo[4,3-a]quinazolin-5-ones and Related Compounds
Authors: El-Sherief H A , Abdel-Rahman A E , El-Naggar G M , Mahmoud A M
Published: July 2006

2-Hydrazino-3-phenyl-4(3H)-quinazolinone (1) underwent ring closure with aliphatic acid, aldehydes, and carbon disulfide to 1-alkyl-, 1-aryl-, and 1-mercapto-4-phenyl-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-ones (7) for instance. The 1-alkylthio-3-phenyl-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-ones were readily obtained from 7 and alkyl halides. Reaction of 1 with ethyl acetoacetate gave the corresponding hydrazone which was readily converted into 2-(3-methyl-5-oxo-2-pyrazolin-1-yl)-3-phenyl-4(3H)-quinazolinone.
Growth Morphology of Alumina Whiskers
Authors: Hayashi Takashi , Iwata Masatoshi , Saito Hajime
Published: July 2006

Alumina whiskers were grown on a substrate by hydrolysis of aluminium fluoride vapor. The present paper describes some observations concerning the growth and morphology of alumina whiskers. The most frequently observed types in this work were A2-whiskers and C-whiskers.
Reaction Mechanism of 2-(Trimethylsilylmethyl)pyridine with Benzonitrile
Authors: Konakahara Takeo , Sato Kenji
Published: July 2006

The mechanism of the reaction of lithiated 2-(trimethylsilylmethyl)pyridine with benzonitrile is discussed. The reaction proceeds through (E)- and (Z)-1-phenyl-2-(2-pyridyl)-1-(trimethylsilylamino)ethene, which are quantitatively converted to 2-phenacylpyridine by acidic hydrolysis.
Tosylation Reaction of d-Glucuronolactone
Authors: Itoh Hiroshi , Tajima Kiyohiko
Published: July 2006

The tosylation reaction of d-glucuronolactone with tosyl chloride in pyridine gave directly 5-O-tosyl-d-glucuronolactone and 2,5-di-O-tosyl-d-glucuronolactone.
An Improved Method for Preparation of N-Alkyl-2(3H)-benzothiazolone Analogs
Authors: Tanabe Yoo , Okabe Takayuki , Kakimizu Akiko , Ohno Nobuo , Yoshioka Hirosuke
Published: July 2006

A number of N-alkyl-2(3H)-benzothiazolone analogs could be prepared from N-monosubstituted aniline and chlorocarbonylsulfenyl chloride. The new method consists of carbamoylation of aniline and successive Friedel-Crafts type ring closure of an intermediate carbamoylsulfenyl chloride in the presence of suitable Lewis or protic acid catalyst.
The Generation of the Ethenethiolate Anion and Its Reaction with Several Chloromethyl Alkyl Ethers and Sulfides
Authors: Tanimoto Shigeo , Ikehira Hideyuki , Oida Tatsuo , Kokubo Toshio
Published: July 2006

2-Ethoxy-1,3-oxathiolane was deprotonated at the 4-position, followed by the cycloelimination of the resultant anion, leading to ethyl formate and the ethenethiolate anion. The anion was trapped by several chloromethyl alkyl ethers and sulfides to afford alkoxy(vinylthio)methanes and alkylthio(vinylthio)methanes respectively.
A Revised Absolute Configuration of 2-Hydroxy-1,1′-binaphthyl
Authors: Kabuto Kuninobu , Yasuhara Fujiko , Yamaguchi Shozo
Published: July 2006

The absolute configuration of 2-hydroxy-1,1′-binaphthyl (3) has been revised to (R)-(+) in THF by a reexamination of the previously reported chemical correlation between 3 and 2,2′-diamino-1,1′-binaphthyl. This revised configuration agreed with that obtained from the assignment by means of the MTPA/LSR method.
Concentration of Organic Pollutants in Water by Evaporation at Reduced Pressure
Authors: Urano Kohei , Yap Seok Ching , Hayashi Koji
Published: July 2006

The relative volatilities α of various organic compounds were obtained as a parameter to determine the recovery for the concentration at reduced pressure and room temperature. The evaporation technique is an efficient method for concentrating large molecular weight compounds and ionizing compounds, if ionization is promoted by adjusting the pH of water.
Catalytic Activity of Sn–Mo Oxides for Propene Oxidation
Authors: Ono Takehiko , Ikehata Tetsuo , Kubokawa Yutaka
Published: July 2006

Sn–Mo oxides were subjected to experimental studies with reference to their catalytic C3H6 oxidation and their own reduction by C3H6. In the oxidation Sn–Mo oxides are 30–40 times more active than MoO3 but only 4–5 times than SnO2. With Sn–Mo oxides as well as SnO2, the oxidation is zero order in C3H6 and about half order in O2, in contrast to those with MoO3. It is proposed that the oxidation proceeds via a redox mechanism with the reduction step proceeding very rapidly. 18O tracer experiments show that the mobility of lattice oxygen in Sn–Mo oxides is lower than that in MoO3 but similar to that in SnO2. From these results together with those of structural studies, it is concluded that the active phase of Sn–Mo oxides is characterized by the MoO3 highly dispersed on SnO2 or Mo ions dissolved in SnO2, and that their high reducibility possibly originates from the existence of SnO2 itself in them.
Polarizability and Electrocapillary Measurements of the Nitrobenzene–Water Interface
Authors: Kakiuchi Takashi , Senda Mitsugi
Published: July 2006

Electrocapillary curves have been measured of the interface between nitrobenzene solution of tetrabutylammonium tetraphenylborate and aqueous solution of lithium chloride using a dropping electrolyte solution electrode under the precise control of the electrical potential difference and of the ion transfer current across the interface. The nitrobenzene–water interface could be electrically polarized over the voltage span of 300 mV. The residual current was explained as due to both the transfer of tetrabutylammonium ion and tetraphenylborate ion through the interface and the charging current at the interface. The electrocapillary curve was parabolic in shape. The surface charge vs. potential curve derived from the electrocapillary curve agreed with that obtained from the differential capacity vs. potential curve of the interface. The results indicate that the interface can virtually be treated as an ideal polarized interface over a certain potential range.
Polarized Raman and Infrared Spectra of Tetramethyl- and 2,6-Dimethylpyrazines
Authors: Ishibashi Yoshimi , Arakawa Fumiko , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

The polarized Raman and infrared spectra of tetramethyl- and 2,6-dimethylpyrazines were studied. Relative intensities of the non-totally symmetric Raman bands for the tetramethylpyrazine crystal were calculated assuming the oriented gas model. Assignments of the fundamental vibrations for tetramethyl- and 2,6-dimethylpyrazines were made through the expected and observed polarization behaviors of the Raman and infrared bands and also through the normal coordinate calculation.