bluuebunny/crossref_metadata_2025 huggingface dataset:
Reflection and Photoconduction Spectra of the Single Crystals of Perylene-TCNQ 1:1 and 3:1 Molecular Complexes
Authors: Ishii Kikujiro , Yakushi Kyuya , Kuroda Haruo , Inokuchi Hiroo
Published: July 2006

Crystal absorption spectra of the two modifications of the perylene-TCNQ (7,7,8,8-tetracyanoquinodimethan) complex were derived from reflection spectra by the Kramers-Kronig transformation and are discussed in relation to the differences in the crystal structures. The spectral response of photoconduction does not show any efficient photocarrier generation in the lowest charge-transfer band region in either modification. However, the rise of the photocurrent of both modifications was found to obey an empirical equation, Y∝(E–Eth)2.5, where Y is the quantum yield of the photocarrier generation, E is the photon energy, and Eth is the threshold energy. Eth of the two modifications is almost the same and falls in the energy region a little above the lowest charge-transfer band. Efficiencies of the carrier generation, on the other hand, are quite different for the two modifications. These photoelectrical characters are discussed in connection with the optical spectra and also with the data of photoelectron emission.
Crystal Structure of (−)474CD mer-{N-(2-Aminoethyl)-1,3-propanediamine}(diethylenetriamine)cobalt(III) Iodide Monohydrate, (−)474CD mer-[Co(aepn)(dien)]I3·H2O
Authors: Ishii Minoru , Sato Shoichi , Saito Yoshihiko , Nakahara Masayoshi
Published: July 2006

The crystal structure of (−)474CD  mer-[Co{N-(2-aminoethyl)-1,3-propanediamine}(diethylenetriamine)]I3·H2O has been determined by means of X-ray diffraction. The crystal is monoclinic, with a space group of P21, a=9.662(2), b=14.602(2), c=8.201(3), β=112.87(4)°, and Z=2. The structure was solved by the Patterson-Fourier method and refined by the full-matrix least-squares method, which yielded an R value of 0.060 for the 2441 observed reflections. Each ligand molecule acts as a terdentate with meridional configurations. The absolute configuration of the coordinated asymmetric nitrogen atom in N-(2-aminoethyl)-1,3-propanediamine was determined to be R. The six-membered chelate ring in N-(2-aminoethyl)-1,3-propanediamine adopts a chair conformation, and the conformation of the five-membered chelate ring is δ. The conformations of the two five-membered chelate rings formed by diethylenetriamine are δ and λ, and the N(secondary)-H bond is oriented toward the six-membered chelate ring formed by N-(2-aminoethyl)-1,3-propanediamine.
Diene-transmissive Diels-Alder Cycloaddition Reaction of Bis(silyloxy) Cross-conjugated Trienes
Authors: Tsuge Otohiko , Wada Eiji , Kanemasa Shuji , Sakoh Hirohiko
Published: July 2006

Multiple Diels-Alder reaction of bis(silyloxy) cross-conjugated trienes is presented. Two trienes, 3-benzylidene- and 3-(methoxymethylene)-2,4-bis(trimethylsilyloxy)-1,4-pentadiene, undergo two sequential Diels-Alder cycloadditions with a variety of dienophiles forming hydronaphthalene rings. Some characteristics of this reaction have been discussed in terms of stereo-, regio-, and chemoselectivity. It is proposed that this process is referred to as “diene-transmissive Diels-Alder reaction”.
Peierls Structure of (H3O)0.33Li0.8[Pt(mnt)2]·1.67H2O
Authors: Kobayashi Akiko , Mori Takehiko , Sasaki Yukiyoshi , Kobayashi Hayao , Ahmad M M , Underhill A E
Published: July 2006

The crystal structure determination of the title compound (abbreviated as α-LiPt(mnt) has been performed at room temperature and 153 K. The [Pt(mnt)2]n− (mnt=1,2-dicyano-1,2-ethylenedithiolato, C4N2S22−) anions stack face-to-face along the c-axis with Pt···Pt distance of 3.6 Å. The room temperature structure and the average structure of the 153 K superstructure are almost the same. The room temperature conductivity of α-LiPt(mnt) is about 200 S cm−1, and the compound undergoes a metal-insulator transition (Peierls transition) at 220 K. In α-LiPt(mnt) the conduction pathway is through the ligand-centered π-system which is composed of predominantly S 3pz orbitals. Oscillation photographs about the c-axis show strong satellite spots on the layerlines of (0.41+n)c* and (0.59+n)c* (n=0, ±1, ±2, ···) The content of Li cation reveals that these satellite spots can be described as 2kF spots. The regular appearance of characteristic satellite reflections indicates that α-LiPt(mnt) has a sinusoidally modulated lattice. The wave vector of the lattice modulation wave is k=0.15b*+0.59c* and the amplitude of the lattice modulation wave is 0.045 a⁄a+0.13b⁄b+0.060c⁄c Å. The overlap integrals along face-to-face stacking directions are much larger than the interstack overlap integrals and the resulting large anisotropy indicates that α-LiPt(mnt) is a one-dimensional metal.
Phosphorylation of Nucleosides with Sodium cyclo-Triphosphate
Authors: Tsuhako Mitsutomo , Fujimoto Mayumi , Ohashi Shigeru , Nariai Hiroyuki , Motooka Itaru
Published: July 2006

Phosphorylation of nucleosides with sodium cyclo-triphosphate (P3m) was studied under various conditions (mixing ratio of P3m to nucleoside, pH, reaction temperature and time). 1) Adenosine, cytidine, guanosine, and uridine were easily phosphorylated by P3m to form selectively nucleoside 2′-monophosphates, 3′-monophosphates, and 2′,3′-cyclic monophosphates. On the other hand, 2′-deoxyadenosine, 3′-deoxyadenosine, 2′-deoxycytidine, and thymidine could not be phosphorylated by P3m. 2) The phosphorylation of adenosine, cytidine, guanosine, and uridine varied strongly, depending on the reaction conditions; mixing ratio, pH, reaction temperature and time. Under conditions of a high mixing ratio of P3m to nucleoside (5:1–10:1), high pH (12–14), high temperature (70–100 °C) for a short time (1–2d) or low temperature (room temperature) for a long time (70–150 d), nucleoside 2′- and 3′-monophosphate could be obtained in high yield (about 50–100%). 3) At the initial stage of the phosphorylation reactions of adenosine, cytidine, and guanosine with P3m, nucleoside 2′,3′-cyclic monophosphates were formed, though a small amount (about 1–3%), but in the course of the reaction for a long time, they were hydrolyzed to nucleoside 2′- and 3′-monophosphates. 4) 2′-deoxyadenosine, 3′-deoxyadenosine, 2′-deoxycytidine, and thymidine could not be phosphorylated by P3m. This means that the presence of hydroxyl groups at the 2′- and 3′-positions of the ribose was necessary for the phosphorylation of nucleosides with P3m. 5) Phosphorylation of nucleosides with short-chain phosphates (ortho-, pyro-, and triphosphate) could not be observed at all. 6) The mechanism of formation of nucleoside 2′-monophosphates, 3′-monophosphates, and 2′,3′-cyclic monophosphates in the phosphorylation of nucleosides with P3m was discussed.
Unstable Excimer Formation in cis-1,2-Di(2-naphthyl)cyclobutane
Authors: Ito Shinzaburo , Yamamoto Masahide , Nishijima Yasunori
Published: July 2006

An unstable intramolecular excimer which is formed in an excited state of cis-1,2-di(2-naphthyl)cyclobutane is investigated. The excimer formation-rate constants and dissociation-rate constants in fluid solutions at low temperatures were determined by picosecond time-resolving measurements. The formation processes are interpreted in relation to the bending motion of the cyclobutane ring. Photophysical characteristics of unstable excimers are shown in this system.
The Synthesis of Partially-protected 2′-Deoxyribonucleotide Dimers by the Selective Phosphorylation of Stannylated Nucleosides
Authors: Kawana Masajiro , Kuzuhara Hiroyoshi
Published: July 2006

A new method for the synthesis of the title compounds is described. The activation of the hydroxyl moieties of 5′-O-dimethoxytrityl and 3′,5′-unprotected 2′-deoxyribonucleosides, which were appropriately protected on their base residues, was done with bis(tributyltin) oxide in separate flasks. The resulting stannylated nucleosides were coupled with 2-chlorophenyl phosphorodichloridate to form the dimers with 3′→5′ internucleotide linkages in yields of more than 71%, along with the corresponding 3′→3′ isomers in yields of less than 10%. The method of Cashion et al. was also evaluated, in which up-to-date protecting groups were employed.
Pressure Effect on Conformational Equilibria of 1,2-Dichloroethane and 1,2-Dibromoethane by Means of Raman Spectroscopy
Authors: Nomura Hiroyasu , Murasawa Kenji , Ito Nobuyuki , Iida Fumisato , Udagawa Yasuo
Published: July 2006

The conformational equilibria of 1,2-dichloroethane and 1,2-dibromoethane have been investigated through a study of the pressure and temperature dependences of these materials in pure liquid states. The volume changes estimated here under a trans-gauche transformation of 1,2-dichloroethane and 1,2-dibromoethane are −2.7±0.4 and −5.2±0.5 cm3/mol, respectively.
Hydrogenation of 3-Ethoxy-1-propene Catalyzed by Supported Nickel Catalysts
Authors: Matsuhashi Hiromi , Hattori Hideshi
Published: July 2006

Nickel catalysts supported on different kinds of metal oxides were prepared to search for active catalysts for 3-ethoxy-1-propene hydrogenation. Ni/ThO2 and Ni/SiO2–Al2O3 catalysts exhibited high activity and selectivity for 1-ethoxypropane, while Ni/MgO, Ni/CaO, and Ni/La2O3 catalysts preferentially catalyzed double bond migration to 1-ethoxy-1-propene which undergo hydrogenation with difficulty.
Preparation of Tetraalkylammonium N-Chloro-p-toluenesulfonamides and Their Application to Imination of Phosphorus Compounds and Sulfides
Authors: Yamamoto Tamotsu , Yoshida Daisaburo , Hojyo Jun , Terauchi Hiranari
Published: July 2006

Tetraalkylammonium N-chloro-p-toluenesulfonamides were prepared from chloramine T and tetraalkylammonium chlorides as a substance corresponding to anhydrous chloramine T, and found to give rise to the effective tosylimination of phosphorus compounds and diaryl sulfides.
One-pot Synthesis of Alkyl Aryl Trithiocarbonates from Benzenethiols, Alkyl Halides, and Carbon Disulfide with a Phase-transfer Catalyst
Authors: Sugawara Akira , Shirahata Masami , Sato Seiki , Sato Ryu
Published: July 2006

Various alkyl aryl trithiocarbonates may readily be synthesized in good yield at low temperatures such as 20 °C by allowing trioctylmethylammonium chloride (phase-transfer catalyst) to catalyze reaction of benzenethiols and alkyl halides with carbon disulfide.
Studies of the Hydrous Tin(IV) Oxide Ion-exchanger. III. Affinity for Cations and Some Applications
Authors: Inoue Yasushi , Yamazaki Hiromichi
Published: July 2006

The distribution coefficients of hydrous tin(IV) oxide for various cations were measured. The affinity series for alkali-metal ions and alkaline-earth-metal ions were Li+>>Na+>K+>Rb+≥Cs+ and Mg2+>Ca2+>Sr2+≈Ba2+ respectively; the values decreased in the order of the increasing crystal radii of the cations. For transition-metal ions, which showed a markedly high affinity, the distribution coefficients had a strong correlation with the hydrolysis constants of the cations and the stability constants of their acetato complexes. Based on these findings, the transition-metal ions are considered to be adsorbed on the exchanger by a bond partially covalent in character, rather than by a pure ionic bond. By using NH4Cl and HClO4 solutions as eluants, nearly quantitative separations of Cs–Na–Li and Cs–Na–Sr were effected with a relatively small column. The applicability of the exchanger to the group separation of actinoids from long-lived fission products was also suggested.
Quantum Chemical Consideration of Substituent Effects on Tautomeric Properties of 2-Pyridones–2-Pyridinols
Authors: Kuzuya Masayuki , Noguchi Akihiro , Okuda Takachiyo
Published: July 2006

The tautomeric properties of 2-pyridones–2-pyridinols exerted by the substituent effect were discussed on the basis of quantum chemical quantities deduced from molecular orbital (MO) calculations. A substituent at the 6-position has the greatest stabilizing effect. The magnitude of this effect was greater on the 2-pyridinol form than the 2-pyridone form, irrespective of the nature of the substituent. This led to a large predominance of the 2-pyridinol form on the 6-polar-substituted derivatives to such an extent that it was observed by conventional UV measurements at ambient temperature. In the 6-methyl derivative, the 2-pyridinol form was not observed by a similar measurement due to the weak substituent effect. The association ability is still an important factor in determining tautomeric equilibrium in a solution, resulting in a strong lability to the molecular environment. The substituent effects on the stabilities of both tautomers were shown to be correlated with the N-atomic charges and ring structural modifications of the tautomers.
Copper(II)–Poly(l-histidine) as an Enzyme Model for l-Ascorbate Oxidase
Authors: Ueda Jun-ichi , Hanaki Akira
Published: July 2006

The autoxidation catalyzed by copper(II)-poly(l-histidine) was studied by a rapid-mixing spectrophotometric method. The reaction obeys Michaelis-Menten kinetics. The double reciprocal plots of the velocity against the concentrations, i.e. the Lineweaver-Burk plots, of ascorbate and of oxygen gave a straight line. A kinetic analysis of the Lineweaver-Burk plot of the reaction reveals that the autoxidation of ascorbate by Cu(II)–PLH proceeds a so-called Ping-Pong mechanism. Copper(II) ion associates with PLH. The rate of ascorbate autoxidation appeared to depend on the concentration of copper(II) ion in the PLH phase, which is designated as the average binding number. The copper(II) ion concentrated in the PLH phase is highly reactive and is likely to be perturbed by the addition of inert electrolytes. The labile copper(II) ion, which is concentrated in the polymer phase, may be the catalytically active species.
p-n Junction Silicon Electrode Coated with Noble Metal for Efficient Solar Photoelectrolysis of Hydrogen Iodide
Authors: Nakato Yoshihiro , Yoshimura Motomu , Hiramoto Masahiro , Tsumura Akira , Murahashi Toshiaki , Tsubomura Hiroshi
Published: July 2006

The photooxidation of iodide ions on n-type silicon electrodes highly doped with boron from the surface in hydrogen iodide or hydrogen iodide/iodine solutions was investigated. Two doping methods were employed: thermal diffusion and ion implantation. The electrode was remarkably stabilized by coating with a 2 to 3 nm-thick platinum layer, followed by heat-treatment at about 400 °C for ca. 10 min. The photocurrent was stable for more than 500 h at a density of the order of 10 mA cm−2. The boron-doped and Pt-coated n-Si electrode also generated a photovoltage much higher than that for a Pt-coated n-Si electrode, showing an advantage of forming the p-n junction. Photoelectrochemical cells made of a boron-doped-Pt-coated n-Si electrode, a platinized Pt counter electrode, and a commercial cation exchange membrane were found to photoelectrolyze hydrogen iodide without externally applied voltage into hydrogen and iodine with a solar-to-chemical energy conversion efficiency (φchems) under simulated AM 1 solar radiation of 8.2%, probably the highest of the φchems values observed for the cells working without external voltage.
Determination of Trace Amounts of Copper as the Complex with Bathocuproinedisulfonate after Enrichment in the Thin Layer of Anion-exchange Resin
Authors: Ohta Masaaki , Ohzeki Kunio
Published: July 2006

A simple and selective method for the determination of trace amounts of copper is developed. The method is based on the concentration of copper as the complex with bathocuproinedisulfonate (BCS) with the use of finely divided anion-exchange resin, collection of the resin on a membrane filter as the disk of thin layer, and determination of the colored complex in the resin phase by densitometry. The copper(I)–BCS complex in sample volumes ranging from 50–200 cm3 was effectively concentrated by factors ranging from 2500–10000. The method was applied to tap water. Copper at ppb (μg dm−3) level was successfully determined.
Optical and ESR Studies on the Micellar Formation with Surfactant Cu(II)–Porphyrin
Authors: Tajima Kunihiko , Ishikawa Yuji , Mukai Kazuo , Ishizu Kazuhiko , Sakurai Hiromu
Published: July 2006

A new surface-active porphyrin, 1-dodecyl-4-(10,15,20-triphenyl-5-porphinyl)pyridinium bromide, and its copper complex (Cu(II)DPyTPP) were synthesized. In toluene, chloroform and ethanol, a typical ESR hyperfine structure (hfs) ascribable to monomeric Cu(II) porphyrin was observed. In ethanol containing a buffer of pH=7.4, a reversible formation of the micellar colloid which is strongly dependent on the water/ethanol mixing ratio, was confirmed based on mearsurements of ESR line broadening and the splitting of the Soret band.
1H-NMR Study of the Aromatic-ring Motion in 3,12-Dithia[4.4]metaparacyclophanes
Authors: Tsuchiya Kazuhiko , Takemura Tetsuo , Mori Nobuo
Published: July 2006

In 10-substituted 3,12-dithia[4.4]metaparacyclophanes, the free energy barrier to the rotation of the para-bridged ring increases with the substituent in the order: H<F<CH3O<Cl, whereas for the flipping of the meta-bridged ring, the order of CH3O and Cl is reversed. This is discussed in terms of the steric-size anisotropy of the CH3O group.
A.c. Polarographic Study of Ion Transfer at the Water/Nitrobenzene Interface
Authors: Osakai Toshiyuki , Kakutani Tadaaki , Senda Mitsugi
Published: July 2006

The transfer of tetramethylammonium (TMA+) ion across the interface between a 0.1 mol dm−3 LiCl aqueous solution and a 0.1 mol dm−3 tetrabutylammonium tetraphenylborate nitrobenzene solution was investigated by means of phase-selective a.c. polarography. In recording the a.c. polarographic current a two-electrode cell system was used and the ohmic drop due to solution resistance in the cell was compensated for by positive feedback. The ion-transfer admittance vs. potential curves were determined in the a.c. frequency range between 10 and 100 Hz and the kinetic parameters of the TMA+-ion transfer across the water/nitrobenzene interface were determined.
The Thermal Intramolecular Redox Reaction of N,N′-Ethylenebis(salicylideneaminato)(2,4-alkanedionato)cobalt(III) in the Solid State
Authors: Kinoshita Setsuko , Miyokawa Kikuo , Wakita Hisanobu , Masuda Isao
Published: July 2006

The title complexes with the [COIII(salen)L2] formula, where salen denotes N,N′-ethylenebis(salicylideneaminato) dianion and L2, bidentate 2,4-alkanedionato anions, like the pent, hex, hept, or non anions, underwent thermally induced, intramolecular one-electron transfer reaction from L2 to Co(III) in the solid state to give [CoII(salen)] in a stoichiometric amount. The gaseous products evolved on the pyrolysis included 1/2 mol of free 2,4-alkanedione, corresponding to the L2 of the complexes, per mole of the complexes. The pyrolysis reaction process was described by the contracting-disk equation for all the complexes. The rate constants increased in the following order of L2: pent<hex<hept<non. The activation enthalpy values were found to increase in the same order. These solid-state reactions are found to be predominantly controlled by the activation entropy.
Hydrophobic Vitamin B12. II. Coordination Geometry and Redox Behavior of Heptamethyl Cobyrinate in Nonaqueous Media
Authors: Murakami Yukito , Hisaeda Yoshio , Kajihara Akiro , Ohno Teruhisa
Published: July 2006

The nuclear cobalt(II) ion in heptamethyl cobyrinate iodide, Cob(II)ester·I, was found to assume a distorted square-planar geometry of Co–N4 type with iodide as a counterion in a polar solvent (methanol) and a square-pyramidal one of Co–N4I type with the iodide ion coordinated at one of the axial positions in apolar solvents such as dichloromethane, benzene, and toluene. The redox chemistry of Cob(II)ester·I and heptamethyl cobyrinate perchlorate, [Cob(II)ester]ClO4, was investigated in various organic solvents by means of cyclic voltammetry and controlled-potential electrolysis. The Co(II)/Co(I) and Co(III)/Co(II) redox potentials for [Cob(II)ester]ClO4 exhibited cathodic shifts as either solvent basicity or polarity was raised, and were found to be in the anodic side relative to the corresponding potentials for CoII(tpp) under identical conditions. The medium effect on the redox behavior of hydrophobic vitamin B12 was discussed in connection with the microenvironmental effect on vitamin B12 placed in the enzyme active sites.
The Ruthenium Catalyzed Synthesis of Quinoline Derivatives from Nitroarenes and Aliphatic Alcohols
Authors: Watanabe Yoshihisa , Tsuji Yasushi , Shida Jun
Published: July 2006

Nitroarenes are reductively converted into quinoline derivatives with aliphatic alcohols in the presence of a catalytic amount of ruthenium compound at 180 °C. Ruthenium(III) chloride is the most effective catalyst. The reaction of nitrobenzene with 1-propanol and 1-butanol gave 2-ethyl-3-methylquinoline and 3-ethyl-2-propylquinoline in 65 and 70% yields respectively. p-Methoxynitrobenzene gave 3-ethyl-6-methoxy-2-propylquinoline in 70% yield with 1-butanol. The reaction appears to include the redox reaction between the nitroarenes and the alcohols, that is, a catalytic hydrogen transfer reaction which generates the aminoarenes and aldehydes. Thus, the alcohol plays roles as both a reductant and an aldehyde precursor.
Reactivities of Stable Rotamers. XII. Reactions of 9-(2-Bromomethyl-6-methylphenyl)fluorene Rotamers with Nucleophiles
Authors: Murata Shigeru , Kanno Seiichiro , Tanabe Yo , Nakamura Mikio , Oki Michinori
Published: July 2006

Rates of some substitution reactions of 9-(2-bromomethyl-6-methylphenyl)fluorene rotamers with nucleophiles are compared. Methanolysis of the rotamers proceeded smoothly in the sp form but was sluggish in the ap. Reactions of the sp form with sodium methoxide afforded 6-methylspiro[benzocyclobutene-1(2H), 9′-[9H]fluorene] and sp-9-(2-methoxymethyl-6-methylphenyl)fluorene, the former being a minor product. In addition to these, isomerization to the ap was detected. In contrast, the ap form afforded the spiro compound as a major product and the ap form of the methoxy compound as a minor product. Menschutkin reactions with pyridine bases were much faster in the sp form than in the ap. These results are attributed to the steric effect in the transition states of the reactions: the sp form reacts much faster than the ap because of the presence of the fluorene moiety in proximity of the reaction site in the latter.
Total Synthesis of Aminoglycoside Antibiotics, Apramycin and Saccharocin (KA-5685)
Authors: Tatsuta Kuniaki , Akimoto Kohji , Takahashi Hideaki , Hamatsu Takao , Annaka Masahiko , Kinoshita Mitsuhiro
Published: July 2006

Apramycin and saccharocin (KA-5685) have been synthesized from previously synthesized neamine (3). Addition of allylmagnesium chloride to 4-O-[3′,4′-O-cyclohexylidene-2′-deoxy-2′-(tosylamino)-α-d-gluco-hexodialdo-1′,5′-pyranosyl]-5,6-O-cyclohexylidene-1,3-di-N-tosyl-2-deoxystreptamine which was derived from 3 through the 6′-N-oxide, gave 4-O-[3′,4′-O-cyclohexylidene-2′,7′,8′,9′-tetradeoxy-2′-(tosylamino)-l-glycero- and d-glycero-α-d-gluco-non-8′-enopyranosyl]-5,6-O-cyclohexylidene-1,3-di-N-tosyl-2-deoxystreptamines which were in turn converted into 4-O-[(8′S)-7′-N,6′-O-carbonyl-2′,3′,7′-trideoxy-8′-O-methyl-7′-(methylamino)-2′-(tosylamino)-d-glycero-α-d-allo-octodialdo-1′,5′:8′,4′-dipyranos-1′-yl]-5,6-O-cyclohexylidene-1,3-di-N-tosyl-2-deoxystreptamine (25), via azidonitration of 1-N-acetyl-4-O-[3′,6′-di-O-acetyl-4′,8′-anhydro-2′,7′-dideoxy-2′-(tosylamino)-l-glycero-α-d-gluco-oct-7′-enopyranos-1′-yl]-5,6-O-cyclohexylidene-1,3-di-N-tosyl-2-deoxystreptamine and epimerization of the 6′-hydroxyl group. Successive deprotection of 25 afforded aprosamine, from which 1,2′,3,7′-tetrakis(N-benzyloxycarbonyl)aprosamine (28) was prepared, and glycosidation of 28 with 4-azido-2,3,6-tri-O-benzyl-4-deoxy-β-d-glucopyranosyl fluoride or 2,3,4,6-tetra-O-benzyl-β-d-glucopyranosyl fluoride, followed by hydrogenolysis, completed the total synthesis.
Preparation of New Nitrogen-bridged Heterocydes. 8. Syntheses of Some Fused Indolizine Derivatives via the Acid-catalyzed Cyclizations of Functionalized 1- and 3-Vinylindolizines
Authors: Kakehi Akikazu , Ito Suketaka , Murakami Shinji , Sano Hiroaki
Published: July 2006

Pyrano[3,2-a] and pyrano[2,3-b]indolizin-2-one derivatives were prepared in 12–86% yields by the acid-catalyzed deacetylation-cyclization of 2-acetoxy-1- and 3-[2-(ethoxycarbonyl)vinyl]indolizines with concentrated sulfuric acid at room temperature. On the other hand, similar reactions of 2-acetoxy-3-[1,2-bis(methoxycarbonyl)vinyl]indolizines did not give the initially expected pyrano[2,3-b]indolizinones at all, but, instead of them, afforded 3-(methoxycarbonylmethylene)furo[2,3-b]indolizin-2-one derivatives in fair yields. Formation mechanisms and some physical properties are also discussed.
Kinetic and Mechanistic Studies on the Kölbel-Engelhardt Reaction over an Iron Oxide Catalyst
Authors: Miyata Yasushi , Akimoto Masamichi , Ooba Nobukazu , Echigoya Etsuro
Published: July 2006

The yield and selectivity to hydrocarbons in the Kölbel-Engelhardt (KE) reaction over a Fe2O3 catalyst at 548–593 K under atmospheric pressure were as low as 0.6–2.2% and 2.0–3.8%, respectively, but the observed four characteristic features of the reaction, i.e., the distribution of produced hydrocarbons following the Schulz-Flory plot, the decrease in propagation probability with increasing reaction temperature, nearly the same value of propagation probability irrespective of a great change in contact time of the reaction, and the remarkable decrease in the yield ratio of olefins to paraffins with increasing contact time of the reaction agreed with the common features of the synthesis of hydrocarbons by the Fischer-Tropsch reaction. The catalyst was composed of Fe3O4 with a low concentration of χ-type carbide (Fe5C2) during the KE reaction, and the results of the effect of contact time on the reaction revealed that formation of hydrocarbons took place following the water-gas shift (WGS) reaction. Furthermore, both the rates of formation of hydrocarbons in the reactions of carbided iron catalyst (Fe5C2) with H2O and with H2 at 573 K were smaller by a factor of >5 than the rate of formation of hydrocarbons in the KE reaction at a steady state at 573 K. Thus, it is concluded that a much greater portion of hydrocarbons produced in the KE reaction was via a sequential reaction pathway involving the WGS reaction followed by the Fischer-Tropsch reaction, not via the decomposition of carbided iron catalyst with H2O and its reduction with H2. Based on the observed increase in the catalytic activity of Fe2O3 upon addition of a small amount of such metal oxides as Cu, Pt, Co, Ni, and Rh oxides, the mechanical mixture of a WGS reaction catalyst and a Fischer-Tropsch reaction catalyst is proposed to be an effective catalyst for the production of hydrocarbons and one illustration of this view is presented.
Catalytic Reduction of 4H-Cyclopenta[def]phenanthrene under Mild Conditions
Authors: Minabe Masahiro , Yamamoto Y\={o}ji , Yoshida Masaaki , Nakada Katsuko , Suzuki Kazuo
Published: July 2006

The catalytic hydrogenation of 4H-cyclopenta[def]phenanthrene over Raney nickel afforded 8,9-dihydro-4H-cyclopenta[def]phenanthrene and 1,2,3,3a-tetrahydro derivative. Under these conditions, di- and tetrahydro compounds were reduced into two diastereomers, cis-3a-cis-9a- and trans-3a-cis-9a-1,2,3,3a,8,9,9a,9b-octahydro-4H-cyclopenta[def]phenanthrene. The reduction over palladium gave a dihydro compound and a platinum catalyst provided products analogous with those obtained over Raney nickel.
Conversion of 2-Sulfinylated 2-Alkenoate Esters to (2E,4E)-2,4-Alkadienoate Esters by Pyrolysis
Authors: Tanikaga Rikuhei , Nozaki Yoshihito , Nishida Masaharu , Kaji Aritsune
Published: July 2006

Thermal reaction of ethyl (2E)-2-phenylsulfinyl-2-alkenoates (E-2) prepared from aldehydes and ethyl 2-phenylsulfinylacetate have been investigated. Refluxing of E-2 or their Z-isomers in xylene resulted in the formation of ethyl (2E,4E)-2,4-alkadienoates accompanied by ethyl (2E)-4-hydroxy-2-alkenoates. Ethyl 2-cycloalkylidene-2-phenylsulfinylacetates were found to be more susceptible to pyrolysis. The enoate esters (2) undergo migration of their carbon-carbon double bond and then [2,3]sigmatropic rearrangement to benzene-sulfenate esters, followed by thermolytic extrusion of a benzenesulfenic acid probably via ethyl (2E)-4-phenyl-sulfinyl-2-alkenoates to afford ethyl (2E,4E)-2,4-alkadienoates.
Palladium Catalyzed C–C Coupling for Synthesis of π-Conjugated Polymers Composed of Arylene and Ethynylene Units
Authors: Sanechika Kenichi , Yamamoto Takakazu , Yamamoto Akio
Published: July 2006

Palladium compounds such as Pd(PPh3)4 and Pd(OAc)2 catalyze polycondensation between dihalo aromatic compounds, X–Ar–X (Ar=p-phenylene, 2,5-thiophenediyl, 9,10-anthracenediyl, 2,6-pyridinediyl, p-benzenedicarbonyl, p-xylene-α,α′-diyl), and acetylenic compounds (p-C6H4(C≡CH)2 or p-C6H4(C≡CMgBr)2). The polymers obtained have high thermal stabilities and most of them show fluorescence. One of the polymers is converted into semiconductors by doping with electron acceptors.
The Reaction of N-Aryl-C-ethoxycarbonylnitrilimine with Olefins
Authors: Shimizu Tomio , Hayashi Yoshiyuki , Nishio Toshiyuki , Teramura Kazuhiro
Published: July 2006

C-Ethoxycarbonylnitrilimines treated with monosubstituted olefins predominantly gave 5-substituted 3-ethoxycarbonyl-2-pyrazolines. From the analysis of the relative rate and regioselectivity of a variety of monosubstituted olefins for the cycloaddition, the nitrilimine is shown to have reactivity and regioselectivity similar to the throughly studied diphenylnitrilimine. The cycloaddition regioselectivity is discussed in terms of frontier orbital energies and coefficients.
Studies of Molecular Complexes of Some II Donors with Iodine by Constant Activity Method
Authors: Shedbalkar Vinay P , Bhat Subray N
Published: July 2006

The iodine complexes of benzene, toluene, o-, m-, p-xylene and mesitylenes in cyclohexane are studied by using constant activity method. The association constants and the other thermodynamic parameters of the complexes are determined and the results are compared with those obtained by using conventional spectral methods. The blue shifted iodine band maxima are determined directly.
Extraction and Spectrophotometric Determination of Iron(III) with N1-Hydroxy-N1,N2-diphenylbenzamidine in Presence of Azide
Authors: Moges Ghirma , Assefa Demirew , Chandravanshi Bhagwan Singh
Published: July 2006

N 1-Hydroxy-N1,N2-diphenylbenzamidine (HDPBA) reacts with iron(III) in the presence of azide to give a violet-coloured complex insoluble in water. The mixed ligand complex having a composition of 1:2:2 (Fe:HDPBA:N3−) is quantitatively extracted into chloroform at pH 2–5. The violet-coloured complex has an absorption maximum at 530 nm with a molar absorptivity of 4900 l mol−1 cm−1. On the basis of this sensitive colour reaction, a highly selective method has been developed for the extraction and spectrophotometric determination of microgram quantities of iron(III). The effect of foreign ions and several experimental variables have been studied. The method is simple, rapid, precise, and free from the regid control of experimental parameters.
XPS Studies of the Platinum Species Photodeposited on Titania from Aqueous Chloroplatinic Acid
Authors: Sungbom Choi , Kawai Maki , Tanaka Kazunori
Published: July 2006

Several Pt/TiO2 catalysts were prepared by photodeposition from aqueous H2PtCl6 in the presence or absence of a CH3COOH–CH3COONa buffer. The examination of these catalysts by X-ray photoelectron spectroscopy (XPS) revealed that the higher the buffer concentration, the more highly reduced the deposited platinum became.
Ring-contracted Crown Ethers: 14-Crown-5, 17-Crown-6, and Their Sila-analogues. Drastic Decrease in Cation-binding Ability
Authors: Ouchi Mikio , Inoue Yoshihisa , Kanzaki Takashi , Hakushi Tadao
Published: July 2006

As compared with symmetrical 3m-crown-m, the ring-contracted(3m–1)-crown-m showed drastic decrease in cation-binding ability, which is attributable not to the diminished cavity size but to the disordered conformation induced by ring contraction.
Mixed Adsorbed Film of 2-(Octylsulfinyl)ethanol with Decylammonium Chloride at Water/Air Interface
Authors: Uryu Shozo , Aratono Makoto , Yamanaka Michio , Motomura Kinsi , Matuura Ryohei
Published: July 2006

The surface tension of the aqueous solution of 2-(octylsulfinyl)ethanol and decylammonium chloride mixture has been measured by changing the total molality and composition of surfactants at 298.15 K under atmospheric pressure. It has been observed that the surface tension decreases with increasing the total molality at a constant composition and with decreasing the composition of decylammonium chloride at a constant total molality. Further the surface tension vs. total molality curve has been found to have a break point at a relatively low concentration. The thermodynamic equations have been developed so as to be applicable to the adsorption of nonionic–ionic mixture and used to calculate the surface density and the surface composition. It has been shown that the surface density vs. molality curve has the discontinuous change caused by the transition from a gaseous to an expanded film. By drawing the two-dimensional phase diagram and comparing it with the diagrams of the ionic–ionic surfactant mixtures, it has been proved that the shape of the phase diagram is affected greatly by the difference in the surface activity between the two surfactants.
Studies of Bitter Peptides from Casein Hydrolyzate. VI. Syntheses and Bitter Taste of BPIc (Val–Tyr–Pro–Phe–Pro–Pro–Gly–Ile–Asn–His) and Its Analogs and Fragments
Authors: Kanehisa Hidenori
Published: July 2006

In order to investigate the relationship between chemical structure and bitter taste, the bitter peptide BPIc (Val–Tyr–Pro–Phe–Pro–Pro–Gly–Ile–Asn–His) isolated from casein hydrolyzate by Minamiura et al. and its analogs and fragments were synthesized. BPIc, whose threshold value of bitter taste was 0.05 mM, was found to be one of the most bitter compounds, like quinine and phenylthiourea. However, [Gly5,6]- and [Gly9,10]-BPIc, and N-terminal octa- and heptapeptide fragments of BPIc possessed much weaker bitterness than BPIc. The results suggested that 5,6-proline and the basic nature of C-terminal are necessary for the strong bitterness exhibited by BPIc.
Syntheses of 2Fe–2S Ferredoxin Model Complexes of Cys-Containing Oligopeptides by Reaction with Fe2S22+ Ion or by Sulfide Incorporation
Authors: Ueyama Norikazu , Ueno Satoru , Nakata Michio , Nakamura Akira
Published: July 2006

The 2Fe–2S ferredoxin model complexes of two peptide ligands, Z–l-Ala–l-Cys–OMe (Z=benzyloxycarbonyl) and Z–l-Cys–l-Ala–l-Ala–l-Cys–OMe, were synthesized from [NMe4]2[Fe2S2Cl4] by addition of triethylamine. These were characterized by absorption, CD, and MCD spectra in dimethyl sulfoxide or N,N-dimethylformamide. Incorporation of inorganic sulfide to the iron(III) complex, [Fe(Z–cys–Ala–Ala–cys–OMe)2]− (rubredoxin models), results in the selective formation of a 2Fe–2S cluster by a controlling ability of the peptides.
Optically Active Anti Head-to-head Coumarin Dimer. Resolution, Absolute Configuration, and Molecular Structure
Authors: Saigo Kazuhiko , Yonezawa Noriyuki , Sekimoto Kazuhiro , Hasegawa Masaki , Ueno Katsuhiko , Nakanishi Hachiro
Published: July 2006

(±)-Anti head-to-head coumarin dimer was successfully resolved into a pair of optically active forms in good yields and in high optical purity by the fractional crystallization of both lactone-opened diamides with optically active 1-phenylethylamine followed by hydrolysis and relactonization. The absolute configuration of (−)589-anti head-to-head coumarin dimer was confirmed to be (3R,3′R,4R,4′R) by X-ray crystal structure analysis, which showed puckering of the cyclobutane ring (32.5°) and some short nonbonded distances (2.15–2.60 Å).
Reaction of Leucocrystal Violet with Tetracyanoethylene and Chloranil II. Solvent Effects
Authors: Nishimura Norio , Motoyama Takushi
Published: July 2006

The proton/deuteron transfer reaction of Leucocrystal Violet(LCV) with tetracyanoethylene(TCNE) and chloranil(CA) in various solvents has been followed spectrophotometrically. It was found that the reaction proceeds slower in polar solvents such as acetonitrile and acetone than in less polar solvents such as chloroform and 1,2-dichloroethane. The rate is remarkably accelerated by pressure indicating probably a substantial polarity increase in the rate processes. The formation of CT complexes was observed at low temperatures. Their nature is presumed to be similar to that of a complex formed by the reaction of CA with N,N-dimethyl-p-toluidine(DMT), and the latter is discussed in connection with the reaction rate of the LCV–TCNE and LCV–CA systems. A possible reaction path is proposed.
Calorimetric Investigation of N-Acyl Amino Acids
Authors: Miyagishi Shigeyoshi , Matsumura Seiichi , Murata Kazuhiko , Asakawa Tsuyoshi , Nishida Morie
Published: July 2006

The melting characteristics of N-acyl amino acids were examined using a differential scanning calorimeter (DSC). The melting-point temperature of N-dodecanoyl l-amino acid increased with the size of its amino acid residue, while the order was opposite for the Dl-amino acids. The racemic derivatives formed racemic compounds in their solid states. Each N-dodecanoyl l-amino acid had a larger enthalpy and entropy-of-fusion than its racemic isomer. Differences in the thermodynamic quantities between the optically active and racemic isomers were larger for N-dodecanoylvaline and -leucine compared with those of N-dodecanoylalanine. A mixture of these molecules were also studied. Each racemic isomer of N-dodecanoylalanine and -leucine partly formed a racemic pair in the liquid state.
Solution Properties of Low Molecular Weight Fractions of Poly(2-vinylpyridine)
Authors: Yoshida Masafumi , Yamaguchi Shinsuke , Sakamoto Noriyuki , Arichi Shizuo
Published: July 2006

The relationships between the weight-average molecular weight Mw and the intrinsic viscosity [η] of poly(2-vinylpyridine) [P2VP] in benzene and methyl alcohol at 25 °C, were investigated by the use of fractions with molecular weights ranging from 2.1×103 to 2.3×104. The exponent ν in the Mark-Houwink-Sakurada equation, [η]=K0Mwν, was 0.5 in both solvents when Mw was lower than about 104. A constant K0 was approximately in accord with Flory’s Kθ value for ordinary high-molecular-weight P2VP, obtained earlier in respective solvents. By measuring [η] for these low-molecular-weight fractions in several solvents at different temperatures, the temperature coefficients of an unperturbed dimension, dln\barr20⁄dT, of this polymer were estimated and averaged to be −2.3×10−3 K−1. These are quite different from the positive values calculated from the Kθ’s by Dondos et al. which were estimated using the extrapolation method for non-θ-solvents. Our results were further corroborated after adding a Kθ value which was directly determined at another θ-state; i.e. in toluene at 63.7 °C, to that in benzene at 16.2 °C published earlier, which was found from phase-separation experiments in this work.
Electronic Spectra of the Aluminum(III) Complexes of 5,10,15,20-Tetraphenylporphin and 2,3,7,8,12,13,17,18-Octaethylporphin
Authors: Kaizu Youkoh , Misu Naoaki , Tsuji Katsuhisa , Kaneko Yoshiaki , Kobayashi Hiroshi
Published: July 2006

Absorption, magnetic circular dichroism (MCD) and emission spectra as well as preparations of the aluminum(III) complexes of 5,10,15,20-tetraphenylporphin (TPP) and 2,3,7,8,12,13,17,18-octaethylporphin (OEP) are presented. On the basis of the spectral observations, the molecular parameters to describe the lowest (π,π*) excited states of a typical metal porphyrin with only minor perturbation by the incorporated tervalent metal ion were determined. The orbital angular momenta in the excited states were evaluated from the MCD spectra as follows: TPPAlCl, Λz=3.0 h in Q00 band, Λz=±0.61 h Ti in B band and OEPAlCl, Λz=±0.61 h Ti in Q00 band, Λz=0.557 h in band. A Davydov splitting of the Soret band observed for the μ-oxo dimer was interpreted in terms of the exciton coupling between two parallel porphyrin chromophores.
General Formulas for Evaluating Ring Currents Induced in a Polycyclic Conjugated System
Authors: Aihara Jun-ichi
Published: July 2006

Two apparently different but physically identical formulas were presented to evaluate bond currents (i.e., ring currents in popular terminology) induced in a polycyclic conjugated system. They are applicable to all kinds of planar conjugated systems.
A Facile Displacement of Tertiary Nitro Group by Hydrogen with Sodium Hydrogentelluride
Authors: Suzuki Hitomi , Takaoka Koji , Osuka Atsuhiro
Published: July 2006

Sodium hydrogentelluride is a useful reagent for replacement of a class of tertiary nitro group by hydrogen.
Calorimetric and Spectrophotometric Studies on Formation of Copper(II) Chloride Complexes in N,N-Dimethylformamide
Authors: Ishiguro Shin-ichi , Jeliazkova Bojana G , Ohtaki Hitoshi
Published: July 2006

Formation of copper(II) chloride complexes has been studied by calorimetric and spectrophotometric titrations in N,N-dimethylformamide (DMF) containing different ionic media, 0.1 and 0.2 mol dm−3(C2H5)4NClO4 and 1 mol dm−3 LiClO4 at 25 °C. In all the DMF solutions examined, calorimetric and spectrophotometric titration curves were well explained in terms of formation of a series of four mononuclear complexes, [CuCln](2−n)+(n=1–4), and formation constants, enthalpies and entropies of formation of the complexes were determined. Formation constants were determined by both calorimetry and spectrophotometry and most of the values obtained by the different methods were in good agreement each other. Calorimetric titration curves obtained in 0.1 and 0.2 mol dm−3 (C2H5)4NClO4 ionic media were practically the same, but they significantly differed from those obtained in 1 mol dm−3 LiClO4 ionic medium, the result indicating that the formation of copper(II) chloride complexes was more favored in the former ionic media than in the latter. Stepwise enthalpies of formation were positive for [CuCl]+, [CuCl2], and [CuCl3]−, but negative for [CuCl4]2− in the (C2H5)4NClO4 DMF solutions, while the values in the 1 mol dm−3 LiClO4 DMF solution were more negative by 6–8 kJ mol−1 than the respective values in the (C2H5)4NClO4 solutions. A significant difference was also found for stepwise entropies of formation of copper(II) chloride complexes between the ionic media. The ionic medium effect on the formation of the complexes found was ascribed to ion pairing of LiCl in the 1 mol dm−3 LiClO4 DMF solution, ion pairing of (C2H5)4NCl being insignificant in the (C2H5)4NClO4 DMF solutions used. A largely negative ΔH4° and a small ΔS4° values in the (C2H5)4NClO4 DMF solutions suggested that solvation of the [CUCl3]− complex was not strong, and thus, release of solvent molecules from the [CUCl3]− complex did not play an important role for the formation of [CuCl4]2−. Therefore, the enthalpy and entropy of formation of [CuCl4]2−. were mainly attributable to those of desolvation of chloride ions and of bond formation between Cl− and [CuCl3]−. The [CuCl4]2− complex may have no DMF molecules in the primary coordination sphere of the central metal ion within the complex. Electronic spectra of individual copper(II) chloride complexes were determined from spectra at various concentrations of chloride ions by using the formation constants obtained.
Benzylphenol Derivatives as Antioxidants for Autoxidation of Tetralin
Authors: Yamada Fukiko , Nishiyama Tomihiro , Suzuura Yasuki , Yamamura Tatsuo
Published: July 2006

A series of 4-benzylphenols, 2-methyl-4-benzylphenols, 4-methyl-2-benzylphenols and 4-methoxy-2-benzylphenols have been prepared and evaluated as antioxidants for tetralin at 60 °C by means of an oxygen-absorption method. Very good activities have been observed with a series of 4-methoxy-2-benzylphenols. The electrochemical oxidation potentials of these compounds were determined using linear-sweep voltammetry. The antioxidative activities were found to correlate with both the 13C NMR chemical shifts (δ) of the ipso-carbon of the OH substituent and their peak potentials (Ep).
The Syntheses and Absolute Configurations of Nellionol and 5-Dehydronellionol
Authors: Matsumoto Takashi , Imai Sachihiko , Yoshinari Takashi
Published: July 2006

To determine the absolute configurations of C-15 in natural nellionol and 5-dehydronellionol, (15R)-8,11,13-abietatriene-12,16-diol was converted into (15R)-6α,11,12,16-tetrahydroxy-8,11,13-abietatrien-7-one (3a) and (15R)-6,11,12,16-tetrahydroxy-5,8,11,13-abietatetraen-7-one (4a), which were identical with natural products. For direct comparisons with 3a and 4a, (15S)-6α,11,12,16-tetrahydroxy-8,11,13-abietatrien-7-one (3b) and (15S)-6,11,12,16-tetrahydroxy-5,8,11,13-abietatetraen-7-one (4b) were also synthesized from (15S)-8,11,13-abietatriene-12,16-diol. The synthetic 3b and 4b were not identical with the natural products. From the present study, the absolute configurations of nellionol and 5-dehydronellionol were conclusively assigned as 5S,6R,10S,15R (3a) and 10R,15R (4a), respectively.
The Magnetic Field Effects on the Electrolysis of Hexacyanoferrate(II) Oxidation and Hexacyanoferrate(III) Reduction
Authors: Watanabe Takeshi , Tanimoto Yoshifumi , Sakata Tadayoshi , Nakagaki Ryoichi , Hiramatsu Mitsuo , Nagakura Saburo
Published: July 2006

The effects of a magnetic field on electrolytic currents in hexacyanoferrate(II) and hexacyanoferrate(III) solutions were studied under various conditions by means of potentiometry. These effects were observed for a wide range of current densities (10−6–10−3 A/cm2). The results were interpreted in terms of the magnetohydrodynamic effect, including a change in the solution density during electrolysis. The present observation suggests that a magnetohydrodynamic flow strongly affects the electrochemical processes on an electrode surface.
Studies of Quenching Processes in NE-213 and Insta-Gel Liquid Scintillators by Using Pulse Shape Discrimination Technique
Authors: Endo Kazutoyo , Saotome Tadafumi , Tanaka Keiko , Nakahara Hiromichi
Published: July 2006

Quenching processes for different excitation sources such as alpha-particles and electrons in NE-213 and Insta-Gel were studied by the use of the pulse shape discrimination technique and pulse height analysis. The dependence on electron energies of time spectra due to the difference in pulse shape was observed for NE-213 by setting energy windows to Compton scattered electrons. The results were interpreted on the basis of the linear energy transfer of electrons in liquid scintillator solution. The chemical and oxygen quenchings in Insta-Gel were compared with each other by using conversion electrons and alpha-particles. Quenching constants for those particles were found to be the same for each organo halogen compound used, irrespective of the excitation sources used. Paramagnetic quenchings were also examined for such agents as oxygen, Gd3+ (4f7), and Yb3+ (4f13) by using the above two excitation sources in Insta-Gel. Possible mechanisms of their effects on the quenching processes were discussed in terms of the spin conversion between the paramagnetic quencher and the excited solvent.
Immunoassay Using a Metal-complex Compound as a Chemiluminescent Catalyst. V. Continuous Immunoassay by the Use of CLCCIA
Authors: Hara Tadashi , Toriyama Motohiro , Imaki Masakatsu
Published: July 2006

Immunoassay, using as a labeling reagent a synthesized metal-complex compound having catalytic activity for a chemiluminescence reaction, was continuously carried out by the sandwich method. The time necessary for all the processes (including: an immune reaction, B/F separation, a sandwich reaction, and a chemiluminescence reaction) was reduced to 50 min. Human serum albumin in the range of 5 ng to 1 μg could be determined (continuously) up to 5 times by the use of the same column (immobilized with an antibody).
Polarized Raman and Infrared Spectra of Tetramethyl-d12-pyrazine
Authors: Maehara Masayoshi , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

Assignments of the normal vibrations of tetramethyl-d12-pyrazine were made based on the polarization behavior of the Raman and infrared bands and also on the normal coordinate calculation. The result ascertains the assignments of the normal vibrations given previously for tetramethylpyrazine.