Bulletin of the Chemical Society of Japan

Yamada, Yoshio; Shiraishi, Minoru; Furuta, Takeshi; Yamakawa, Toshio; Sanada, Yuzo

doi: 10.1246/bcsj.57.3027pmid: N/A

The effect of hydrogenation of carbonized pitch on its solubility in quinoline was investigated in connection with structural changes of the pitch during carbonization. Naphtha-tar pitch (NTP) and acenaphthylene were carbonized at 673 and 703 K, respectively, for various periods of time. The pitches thus heat-treated were hydrogenated by BenKeser reaction and the amount of quinoline insolubles (QI) in the hydrogenated pitch was determined. An acenaphthylene pitch (ACP) heat-treated for 24 h was rendered completely soluble into quinoline by the hydrogenation, whereas a considerable amount of insolubles was left in the case of NTP treated for longer residence times than 8 h. This can be explained in terms of the difference in interaction among aromatic molecules constituting the QI components derived from NTP and ACP. ACPs doped with elemental sulfur left a significant quantity of QI after the hydrogenation. The addition of sulfur is considered to form crosslinking bonds between aromatic molecules through hydrogen abstraction by the sulfur. When QI separated from carbonized NTP was hydrogenated, the degree of conversion into quinoline solubles (QS) was low as compared with that for the whole sample of the same NTP. The presence of QS in the pitch plays a very important role for the hydrogenation.

Sotani, Noriyuki; Yoshida, Noritetsu; Kawamoto, Yoji; Kishimoto, Shozo; Hasegawa, Masatomo

doi: 10.1246/bcsj.57.3032pmid: N/A

The decomposition process of orthorhombic hydrogen molybdenum bronze, H0.30MoO3, was studied by the temperature programmed decomposition (TPD) technique in vacuo and in helium gas. The only gas liberated during the decomposition was H2O and no other gas was detected. The TPD spectrum above 150 °C was composed of three bands (PII, PIII, and PIV). The PII band corresponded to the process from H0.30MoO3 to H0.21MoO2.95 without any structural change. The PIII band corresponded to the process from H0.21MoO2.95 to H0.06MoO2.88 with the structural change and the PIV band, to the process from H0.06MoO2.88 to MoO2.85.

Hasunuma, Masahiko; Okada, Keiko; Kato, Yoshifumi

doi: 10.1246/bcsj.57.3036pmid: N/A

The (f,f*) transitions of europium tris(bromate) enneahydrate crystal between 12000 and 20000 cm−1 were measured at 95 K by laser-excited fluorescence spectroscopy. The crystal field components of the ground (7F0.1···6) and the excited states (5D0.1) participating in the transitions were analyzed in terms of the tensor-operator method. Besides electric-dipole transitions, a number of magnetic-dipole transitions were detected in compliance with the selection rule. The theory could reproduce the observed wavenumbers and intensities both for the σ- and π-transitions. The population ratio of the 5D0 to the 5D1 was estimated to be 14.1 from the intensity calculations and the observed results. The result suggests that mixing of g-orbitals is significant for the forced electric-dipole transitions.

Ishii, Kikujiro; Yakushi, Kyuya; Kuroda, Haruo; Inokuchi, Hiroo

doi: 10.1246/bcsj.57.3043pmid: N/A

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.

Oonishi, Isao; Fujisawa, Shoji; Aoki, Junji; Ohashi, Yuji; Sasada, Yoshio

doi: 10.1246/bcsj.57.3048pmid: N/A

Crystals of the title compound, C21H12O, are orthorhombic, belong to the space group Pn21a, have lattice constants of a=14.227(3), b=15.551(4), c=12.436(3) Å, and also have Z=8. The structure was determined using the direct method and was refined by using a full-matrix least-squares method to an R value of 0.106 on the basis of 1964 reflections with |Fo|>3σ(|Fo|). The molecules is slightly distorted from the planar conformation owing to a steric repulsion between the O and H atoms. The molecules are stacked in pairs and two pairs with different overlapping modes are randomly arranged with different populations. It has been qualitatively explained that the populations of disordered molecules reflect the difference in their lattice energies.

Kato, Noriyuki; Miyazaki, Tetsuo; Kawai, Yukihiro; Fueki, Kenji

doi: 10.1246/bcsj.57.3052pmid: N/A

The decay-rate constants, k, of dipentyl disulfide anions or benzyl radicals in 1-propanol and ethanol were measured over a temperature range of 107–230 K by pulse- and γ-radiolysis method. The decay-rate constants were found to range over nine orders of magnitude. The decay kinetics is a composite first-order reaction. Since the decay rates of reaction intermediates observed are diffusion-controlled, the decay-rate constants represent directly the rates of molecular transport in the supercooled liquids. It was found that the temperature dependence of the decay-rate constants could be expressed by the following equation.log\frackT=−\fracAT–Tg+B,where T is the absolute temperature, A and B are constants. Tg is the glass transition temperature. The molecular diffusion of the ions or radicals in the supercooled liquids was completely suppressed at the glass transition temperature. The temperature dependence of the decay-rate constant was compared with that of the viscosity of the matrix. It was found that the temperature, at which the molecular diffusion is completely suppressed is much higher than the temperature at which the viscosity is infinite.

Furukawa, Junichi; Murata, Shigeo; Sakiyama, Minoru; Seki, Syûzô

doi: 10.1246/bcsj.57.3058pmid: N/A

Standard enthalpies of combustion and of sublimation at 298.15 K were determined and standard enthalpies of formation in crystalline and gaseous states were derived for N,N-dimethyl-3- and N,N-dimethyl-4-nitroanilines by calorimetric measurements. Stabilization energies due to the intramolecular interaction between substituents were evaluated and discussed for these compounds and 3- and 4-nitroanilines.

Ito, Yoshiro; Arai, Shigeyoshi

doi: 10.1246/bcsj.57.3062pmid: N/A

Excited diatomic molecules of krypton and xenon in 13Σu+ states, Kr2* and Xe2*, were produced by irradiating krypton and xenon in the presence of an excess of argon with short electron-beam pulses. The kinetic behaviors of Kr2* and Xe2* (monitored by near-IR absorption spectrophotometry) are explained quantitatively in terms of mechanisms involving three-body association and radiative decay. The rate constants were found to be (6.5±0.8)×10−33 cm6s−1 for Kr*+Kr+Ar→Kr2*+Ar and (1.6±0.3)×10−32 cm6 s−1 for Xe*+Xe+Ar→Xe2*+Ar. The rate constants for the quenching reactions of Kr2* were determined for Xe, H2, O2, N2, CO, and NO.

Nosaka, Yoshio; Ishizuka, Yutaka; Norimatsu, Kohji; Miyama, Hajime

doi: 10.1246/bcsj.57.3066pmid: N/A

Ammonia was formed photocatalytically from an aqueous solution of azide ion by using illuminated Pt/TiO2 semiconductor powder. The reaction products, NH3, N2, and small amounts of N2O and NO3−, were detected. Hydrogen, O2 and N2H4 were not formed in the primary reaction products. From these results, together with photoelectrochemical measurements, a mechanism of the ammonia formation from azide ion and water is presented.

Takimoto, Midori; Takenaka, Akio; Sasada, Yoshio

doi: 10.1246/bcsj.57.3070pmid: N/A

3-(Adenin-9-yl)-N-(2-succinimidyl)propionamide has been synthesized as a model for studying the interaction between cyclic ureide and adenine, and its crystal structure examined. The crystals are monoclinic, the space group P21/c, with unit-cell dimensions of a=10.861(1), b=12.766(1), c=9.753(1) Å, β=91.10(1)°, and Z=4. The ureide moiety is hydrogen bonded to adenine with NH···N(1) (2.903(3) Å) and O···HN(6) (2.955(3) Å). A comparison of the hydrogen bonding patterns of the related compounds with adenine suggests that cyclic ureide anticonvulsant drugs possess the capability of interacting with N(1) and N(6) sites of adenine.