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101.
102.
Ohkura K Ishihara T Nishijima K Diakur JM Seki K 《Chemical & pharmaceutical bulletin》2005,53(2):258-259
Upon UV-irradiation in the presence of piperylene, 5-fluoro-1,3-dimethyluracil (5-FDMU) couples with naphthalenes having either an electron-withdrawing group or an electron-donating group by way of 1,2-cycloaddition via mode selectivity to give the corresponding naphthocyclobutapyrimidines regio- and stereo-selectively. 相似文献
103.
Kyoichi Oki Seiji Yamada Sachiko Tsuchida Hiromasa Nishikiori Nobuaki Tanaka Tsuneo Fujii 《Research on Chemical Intermediates》2003,29(7-9):827-837
The photocatalytic degradation and isomerization of trans- and cis-1,2-dichloroethenes (1,2-DCEs) by TiO2 photocatalyst have been investigated using gas chromatography. The reaction half-life of 1,2-DCEs in nitrogen was longer than in dry air and oxygen, and the initial concentration of them affects the extent of the isomerization. The results indicate that the oxygen molecule and chlorine atoms play an important role in the degradation and isomerization of 1,2-DCE. It is also apparent that the photocatalytic degradation of 1,2-DCEs occurs on the TiO2 surface. 相似文献
104.
Yuki Wakisaka Daiki Kido Hiromitsu Uehara Qiuyi Yuan Felix E. Feiten Shingo Mukai Satoru Takakusagi Yohei Uemura Toshihiko Yokoyama Takahiro Wada Motohiro Uo Oki Sekizawa Tomoya Uruga Yasuhiro Iwasawa Kiyotaka Asakura 《Chemical record (New York, N.Y.)》2019,19(7):1157-1165
Surface fluorescence X‐ray absorption fine structure (XAFS) spectroscopy using a Laue‐type monochromator has been developed to acquire structural information about metals with a very low concentrate on a flat highly oriented pyrolytic graphite (HOPG) surface in the presence of electrolytes. Generally, surface fluorescence XAFS spectroscopy is hindered by strong scattering from the bulk, which often chokes the pulse counting detector. In this work, we show that a bent crystal Laue analyzer (BCLA) can efficiently remove the scattered X‐rays from the bulk even in the presence of solution. We applied the technique to submonolayer (~1014 atoms cm?2) Pt on HOPG and successfully obtained high signal/noise in situ XAFS data in combination with back‐illuminated fluorescence XAFS (BI‐FXAFS) spectroscopy. This technique allows in situ XAFS measurements of flat electrode surfaces to be performed in the presence of electrolytes. 相似文献
105.
Dr. Kohei Fuchibe Hibiki Hatta Dr. Ken Oh Rie Oki Prof. Dr. Junji Ichikawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5984-5987
Activation of the sp3 C−F bond in 2-trifluoromethyl-1-alkenes was accomplished through treatment with a Lewis acid. In the presence of an equimolar amount of EtAlCl2, the (trifluoromethyl)alkenes readily underwent an SN1′-type reaction with arenes through a Friedel–Crafts-type mechanism via elimination of a fluoride ion to afford 3,3-difluoroallylated arenes in good yields. This selective activation of one C−F bond of the CF3 group provides a synthetic method for accessing biologically and synthetically important 1,1-difluoro-1-alkenes. 相似文献
106.
Dr. Tomoyuki Ikai Dr. Masaki Ito Dr. Kosuke Oki Dr. Nozomu Suzuki Prof. Eiji Yashima 《Angewandte Chemie (International ed. in English)》2023,62(31):e202306252
A series of poly(biarylylacetylene)s (PBAs) bearing axially-chiral (S)-and (R)-pyridyl-N-oxide residues with a methoxy, propoxy, or acetyloxy substituent at the 3-position of the biaryl units was synthesized. All the PBAs formed a preferred-handed helix, while the helical sense preference was varied depending on the substituents despite the same twist-sense of the biaryl units. Among them, the propoxy-bound helical PBA showed an exceptionally high chiral recognition ability as a chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) and efficiently resolved not only various chiral aromatic alcohols, but also a variety of chiral aliphatic alcohols; the latter still remains difficult to resolve by commercially-available CSPs in HPLC. Such practically-useful both handed helical PBA-based CSPs can be produced from the racemic PBA composed of fully racemic monomer units through deracemization of the biaryl units with a chiral alcohol. 相似文献
107.
In this paper, a finite element formulation, used to analyze the contact-impact behavior of geared rotor systems coupled with the rotational, lateral, and axial vibrations between gears at high rotational speeds, has been developed. A gear impact element to model the contact-impact behavior between gears has been developed and its numerical method is discussed. A relative displacement measurement idea has been proposed to measure vibration parameter for contrast experiment in high rotational geared system. The equations of motion are derived and solved iteratively during each time increment until the unbalanced force decrease to an acceptable tolerance level. Based on the proposed method, an analysis program, GEARS, has been developed. The contact-impact behavior of geared rotor systems is analyzed especially under high rotational speed condition as numerical examples, which are demonstrated to show the effectiveness of the proposed method. 相似文献
108.
The hydrogenation of ethylene on Ni(1 0 0) surface has been studied by TDS. The decrease in the bonding energy with increasing coverage is revealed for both of adsorbed hydrogen and ethylene by the shift of desorption to lower temperatures. Ethane formation is only observed on the preadsorbed hydrogen coverage exceeding 0.5 monolayer (ML), coupled with the growth of H2 shoulder peak at lower temperatures. Further increase of H coverage to saturation reduces the bonding energy of subsequently adsorbed ethylene by 15 kJ/mol and decreases the saturation coverage of ethylene to about one-third on the clean surface. This leads to the shift of ethane desorption from 250 to 220 K and an appearance of additional ethane peak at 180 K. The latter ethane formation coincides with the hydrogenation of surface ethyl species derived from ethyl iodide as a precursor. It indicates that the rate of ethyl formation on the surface would be comparable to that of subsequent hydrogen addition to the surface ethyl species in the hydrogenation of ethylene when the preadsorbed hydrogen coverage approaches 1.0 ML. 相似文献
109.
Dr. Wei Zheng Dr. Kosuke Oki Dr. Ranajit Saha Dr. Yuh Hijikata Prof. Eiji Yashima Dr. Tomoyuki Ikai 《Angewandte Chemie (International ed. in English)》2023,62(11):e202218297
Defect-free one-handed contracted helical tubular ladder polymers with a π-electron-rich cylindrical helical cavity were synthesized by alkyne benzannulations of the random-coil precursor polymers containing 6,6′-linked-1,1′-spirobiindane-7,7′-diol-based chiral monomer units. The resulting tightly-twisted helical tubular ladder polymers showed remarkably high enantioseparation abilities toward a variety of chiral hydrophobic aromatics with point, axial, and planar chiralities. The random-coil precursor polymer and analogous rigid-rod extended helical ribbon-like ladder polymer with no internal helical cavity exhibited no resolution abilities. The molecular dynamics simulations suggested that the π-electron-rich cylindrical helical cavity formed in the tightly-twisted tubular helical ladder structures is of key importance for producing the highly-enantioseparation ability, by which chiral aromatics can be enantioselectively encapsulated by specific π-π and/or hydrophobic interactions. 相似文献
110.