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91.
Photon-stimulated ion desorption from deuterated formic acid chemisorbed on Si(100) has been studied using pulsed synchrotron radiation in the energy region of the oxygen 1s electron excitation. The O 1s electrons of hydroxyl oxygen and carbonyl oxygen could be selectively excited in the O K-edge region because the chemical environments are different. It is found that the CDO+ yield is enhanced at the O 1s(C---O)→σ*(C---O) resonance and the CD+ yield at the O 1s(C=O)→σ*(C---O) resonance. The results indicate that ion desorption is related both to the antibonding character of excited molecular orbitals and the local character of core hole orbitals. 相似文献
92.
93.
We have investigated the photon-stimulated ion-desorption from deuterated formic acid (DCOOD) monolayer chemisorbed on Si(100) crystal by applying a photoion-photoion-coincidence technique. The true-coincidence yields of an ion pair C+---D+ are given in the photon energy range (275–400 eV) above the C 1s absorption edge. The partial ion yields and Auger electron yields re presented for comparison. It was found that the multielectron (shake-off) excitation promotes the multiple bond-breaking of the adsorbate and the ion pair C+–D+ desorption events. 相似文献
94.
Hidetoshi Sekiguchi Atsushi Kanzawa Takuya Honda 《Plasma Chemistry and Plasma Processing》1989,9(2):257-275
Effects of the thermal quenching process in the synthesis of NO and the decomposition of CO2 were studied using a thermal argon plasma and different-i.d. cooling tubes. Four tubes of different i.d.'s were used to change the cooling rate. The conversions obtained in both reactions increased with decreasing quenching tube diameter. Furthermore, the concept of quenching temperature was introduced. This temperature was obtained from two time constants of reaction and cooling rate. The conversions into CO can be estimated in a similar manner to the NO synthesis with a proper modification for radicals which remain at high concentrations at the quenching temperature. 相似文献
95.
The 3H-disilagermirene, (tBu2MeSi)4GeSi2, reacts with alpha-hydrogen containing carbonyl compounds (acetophenone, butane-2,3-dione) by an 'ene'-reaction pathway followed by isomerization or insertion reactions, representing a new mode in the reaction of disilenes with carbonyl compounds. 相似文献
96.
Kawasaki T Ogawa A Terashima R Saheki T Ban N Sekiguchi H Sakaguchi KE Sakamoto M 《The Journal of organic chemistry》2005,70(8):2957-2966
Hexahydropyrrolo[2,3-b]indoles 6 were synthesized in five steps from indolin-3-one 8 by a general and efficient method, in which elements of molecular diversity were readily added onto the 3a-position of the pyrrolo[2,3-b]indole ring system. Horner-Wadsworth-Emmons reaction of 2-allyloxyindolin-3-ones 7, derived from indolin-3-one 8 and a variety of allylic alcohols, smoothly proceeded with successive Claisen rearrangement to give the corresponding 3-allyl-3-cyanomethylindolin-2-ones 15. Indolin-2-ones 15 were converted into pyrrolo[2,3-b]indoles 6 using partial hydrolysis followed by reductive cyclization with LiAlH(4). Synthesis of N-methylated pyrrolo[2,3-b]indole derivatives 23 and 26 is also described. 相似文献
97.
VladimirYa. Lee Akira Sekiguchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2007,119(35):6716-6740
Die Aromatizität ist eines der wegweisenden Konzepte in der Chemie, dessen Geschichte sich über fast zwei Jahrhunderte erstreckt, beginnend mit der Entdeckung des “Doppelt‐Kohlenwasserstoffs” (bicarburet of hydrogen), heute Benzol genannt, durch Faraday. Die seitherigen Fortschritte auf dem Gebiet der aromatischen Verbindungen sind erheblich, was sich in der Synthese neuartiger Klassen aromatischer Verbindungen widerspiegelt, darunter geladene Spezies, nichtklassische (Möbius‐, dreidimensionale, Homo‐, Metalla‐)Arene und Fullerene. Zugleich wurde die Theorie der Aromatizität stetig weiterentwickelt; die Abgrenzung der Aromatizität erfordert heute eine Abwägung vielfältiger Kriterien: energetischer, struktureller, magnetischer Kriterien usw. Im vorliegenden Aufsatz diskutieren wir den derzeitigen Forschungsstand auf dem Gebiet der aromatischen Verbindungen von schwereren Gruppe‐14‐Elementen und geben einen Ausblick auf die Zukunft dieses Gebiets. 相似文献
98.
The first green and practical method for "aerobic hydrogenation" involving the use of hydrazine and an organocatalyst is described. Olefins can be hydrogenated by treatment with hydrazine in the presence of a 5-ethyl-3-methyllumiflavinium perchlorate (FlEt+.ClO4-) catalyst under O2 atmosphere to give the corresponding hydrogenated products in excellent yields along with environmentally benign water and molecular nitrogen as the only waste products. 相似文献
99.
Hans R. Kricheldorf Bernard Coutin Hikaru Sekiguchi 《Journal of polymer science. Part A, Polymer chemistry》1982,20(9):2353-2370
Copolymerizations of pyrrolidone-2 (γ-butyrolactam) with piperidone-2 (δ-valerolactam) and azepinone-2 (ε-caprolactam) and the copolymerization of piperidone-2 with azepinone-2 were studied in bulk at 30 or 45°C. The sodium salt and the tetramethylammonium salt of pyrrolidone-2 were used as catalysts and N-acetylpyrrolidone-2 as cocatalyst. The sequences of the resulting copolyamides were analyzed by means of 22.63-MHz 13C-NMR spectra. All sequences were nearly random in nature, yet copolymerizations of pyrrolidone-2 favor slightly the formation of alternating sequences. Furthermore, the rate of incorporation of pyrrolidone is higher than that of the two comonomers in contrast to experiments at temperatures above 100°C. The influence of transamidation reactions on the sequences is discussed. Propagation/degradation equilibria involving N-acyllactam chain ends were found to modify the initially formed, kinetically controlled sequences in direction of thermodynamically controlled ones. 相似文献
100.
The absolute configuration of rutaretin methylether(1) has been established by transformation of it into methyl hexahydrorutaretin methyl ether (5) which was independently derived from S-marmesin (2) via photo-Fries reaction as a key step. 相似文献