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71.
Akira Nishinaga Toshio Itahara Tadashi Shimizu Haruo Tomita Kanji Nishizawa Teruo Matsuura 《Photochemistry and photobiology》1978,28(4-5):687-692
Abstract— The mechanisms by which 4-substituted 2,6-di- t -butylphenols are oxygenated by base- and Co(II) Schiff base complex-catalysis into o - or p -peroxyquinols and their Co(III) complexes, respectively, have been investigated. For the base-catalyzed oxygenation, a one-step ionic mechanism involving no radical species is suggested to be the most probable one. For the formation of the peroxycobalt(III) complexes, the following stoichiometry is concluded: ArOH + Co(II) + 5/4 O2 → peroxycobalt(III) complex + 1/2 H2 O. A mechanism involving an electron transfer between the phenols and the Co(II)-O2 complex followed by further electron transfer between the formed phenoxy radicals and the Co(II) complex to give the corresponding phenolate anions is proposed. 相似文献
72.
Masaki Kashiwara Takahiro Kawai Toshio Oshima 《Communications in Mathematical Physics》1978,60(2):97-130
We use the holonomic character of Feynman integrals to describe their singularity structure explicitly in some simple cases. The results in §1 show that under moderate conditions Feynman amplitudes can be locally expressed essentially in terms of Legendre functions near the points where two positive- Landau-Nakanishi surfaces meet. Related topics such as hierarchical principle in perturbation theory are also discussed in terms of holonomic systems involved. In §4 we use the concrete expressions for Feynman amplitudes obtained in §1 to discuss the validity of Sato's conjecture.Supported in part by NSF MCS 75-2333Supported in part by NSF GP 36269 相似文献
73.
Toshio Niwa 《Journal of statistical physics》1978,18(3):309-317
We investigate the time evolution of a simple one-dimensional system with an infinite number of particles. We calculate some time correlation functions and show that they behave asymptotically as 1/t. 相似文献
74.
Hiroshi Tajima Toshio Masuda Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1987,25(8):2033-2042
Polymerization of HC?CSiMe3 homologues (HC?CSiMe2R; R = n-C6H13, CH2CH2Ph, CH2Ph, Ph, and t-Bu) was studied by use of W and Mo catalysts. W catalysts provided polymers in good yields from all these monomers. Mo catalysts gave mainly a polymer from HC?CSiMe2–t-Bu, but virturally only cyclotrimers from sterically less croweded monomers (R = n-C6H13, CH2CH2Ph, CH2Ph, and Ph). Polymers with flexible R groups (n-C6H13, CH2CH2Ph, and CH2Ph) were totally soluble, their number-average molecular weights being 7000–18,000. Polymers with inflexible R groups (Ph and t-Bu) were partly insoluble. Every polymer was a yellow rubber or powder, and had the structure, \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH} = {\rm C}\left( {{\rm SiMe}_{\rm 2} {\rm R}} \right)\rlap{--} ]_n $\end{document}. The results were compared with the polymerization and polymer of HC?CSiMe3. 相似文献
75.
Tomoko Sotomatsu Yoshiyuki Murata Toshio Fujita 《Journal of computational chemistry》1991,12(1):135-138
The AM1 calculation was done for ortho-substituted toluenes (o-X-C6H4-CH3) and ortho-substituted tert-butylbenzenes (o-X-C6H4-t-Bu). The difference in the calculated heat of formation between o-X-C6H4-CH3 and o-X-C6H4-t-Bu was used as a theoretical steric index for ortho-X. The correlation of this theoretical steric index with the empirical steric parameter sets such as our recently defined Es(AMD) and the Taft–Kutter–Hansch (TKH) Es was examined. In spite of the simplicity of the model system, the theoretical index was linear with the Es(AMD) constant with a correlation coefficient of r = 0.972 for 17 substituents of various structures. Including the phenyl group, the correlation with the TKH Es constant was r = 0.948. The theoretically calculated index was shown to serve as a measure of the ortho steric effect. 相似文献
76.
Tsukasa Matsunaga YURI HATAKEYAMA Michi Ohta Toshio Mori Osamu Nikaido 《Photochemistry and photobiology》1993,57(S1):934-940
Abstract— We established a monoclonal antibody(DEM–1) that recognizes UV-induced DNA damage other than cyclobutane pyrimidine dimers or(6–4)photoproducts. The binding ofDEM–1 antibody to 254 nm UV-irradiated DNA increased with subsequent exposure to UV wavelengths longer than 310 nm, whereas that of the 64M-2 antibody specific for the(6–4)photoproduct decreased with this treatment. Furthermore, the increase inDEM–1 binding was inhibited by the presence of the 64M-2 antibody during the exposure. We concluded that theDEM–1 antibody specifically recognized the Dewar photoproduct, which is the isomeric form of the(6–4)photoproduct. TheDEM–1 antibody, however, also bound to DNA irradiated with high fluences of 254 nm UV, suggesting that 254 nm UV could induce Dewar photoproducts without subsequent exposure to longer wavelengths of UV. Furthermore, an action spectral study demonstrated that 254 nm was the most efficient wavelength for Dewar photoproduct induction in the region from 254 to 365 nm, as well as cyclobutane dimers and(6–4)photoproducts, although the action spectrum values in the U V-B region were significantly higher compared with those for cyclobutane dimer and(6–4)photoproduct induction. 相似文献
77.
Yoshizumi Ishikawa Hideyasu Honda Yoshiyuki Sugahara 《Journal of Sol-Gel Science and Technology》2000,19(1-3):365-369
The conversion of tetrakis(diethylamino)titanium (Ti(NEt2)4) into titania via either a combination of hydrolysis (Ti(NEt2)4 : THF : H2O = 1 : 10 : x, x = 2, 4, 10) at ambient conditions and calcination (method A) or hydrolysis in a water-tetrahydrofuran (THF) mixture (Ti(NEt2)4 : THF : H2O = 1 : 10 : 100) at reflux (method B) was investigated. Titanium tertiary butoxide (Ti(O
t
Bu)4) was also used as a substitute for Ti(NEt2)4. The hydrolysis via method A resulted in the formation of amorphous solids containing organics. Thermal analyses showed that the hydrolysis products showed mass losses up to 500°C probably due to the presence of diethylamine (Et2NH) formed via the hydrolysis of Ti(NEt2)4 in the hydrolysis products, while a mass loss of the hydrolysis product from Ti(O
t
Bu)4 was completed up to about 200°C. After calcination at 600°C, anatase or a mixture of anatase and rutile was obtained. The crystallization behavior of the hydrolysis products from Ti(NEt2)4 was different from that of the hydrolysis product from Ti(O
t
Bu)4. The hydrolysis via method B gave only an amorphous material from Ti(NEt2)4, while a crystalline titania (anatase and brookite) formed from Ti(O
t
Bu)4. 相似文献
78.
Yoshiharu Abe Toshio Masuda Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1989,27(13):4267-4279
(o-Methylphenyl)acetylene polymerized with high yields in the presence of W and Mo catalysts. W catalysts were more active than the corresponding Mo catalysts. The weight-average molecular weight of the polymer formed with W(CO)6–CCl4–hv reached 8 × 105, being higher than the maximum value (ca. 2 × 105) for poly(phenylacetylene). The polymer had the structure $\rlap{--} [{\rm CH} \hbox{=\hskip-1pt=} {\rm C}(o - {\rm CH}_3 {\rm C}_6 {\rm H}_4 )\rlap{--} ]_n $. The stereochemical structure of the main chain could be determined by 13C-NMR; the cis content varied in a range of 41–61% depending on the polymerization conditions. The present polymer was thermally more stable than poly(phenylacetylene) according to thermogravimetric analysis. Interestingly, this polymer possessed deeper color than poly(phenylacetylene), and showed a fairly strong absorption in the visible region. 相似文献
79.
Toshio Yamanaka Mitsuru Ohkubo Fumie Takahashi Masayuki Kato 《Tetrahedron letters》2004,45(13):2843-2845
An efficient synthesis of the orally-active GpIIb/IIIa antagonist FR184764 was achieved. The key intermediate, an optically active ethynyl β-amino ester, was synthesized efficiently by utilizing a lipase catalyzed kinetic resolution step. 相似文献
80.
Kasai HF Tsubuki M Matsumoto Y Shirao M Takahashi K Honda T Ueda H 《Chemical & pharmaceutical bulletin》2004,52(3):311-315
Gas chromatographic separations of the stereoisomers of menthol derivatives, important intermediates in the synthesis of physiologically active natural products, were carried out on several substituted beta-cyclodextrin (CD) columns, including per-O-methyl-beta-cyclodextrin (PME-beta-CD), heptakis(2,3-di-O-acetyl-6-tert-butyldimethylsilyl)-beta-CD (DIAC-6-TBDS-beta-CD), and heptakis(2,3-di-O-methyl-6-tert-butyldimethylsilyl)-beta-CD (DIME-6-TBDS-beta-CD) as chiral stationary phases (CSPs). With the DIME-6-TBDS-beta-CD column, a separation of the Z- and E-isomers of methylidenementhol was accomplished; no separation was achieved with the other columns. The stereoisomers of methylidenementhol and the corresponding tert-butyldimethylsilyl (TBS) ether were separated on both the beta-CD and the heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TME-beta-CD) columns by high-performance liquid chromatography (HPLC) with a mobile phase involving acetonitrile and H(2)O. For the separation of the Z- and E-isomers of methylidenementhol, the TME-beta-CD column was superior. In contrast, the beta-CD column was preferable in the case of the corresponding TBS ether. 相似文献