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排序方式: 共有134条查询结果,搜索用时 31 毫秒
1.
2.
Akiya Karen Noriaki Ikeda Noboru Mataga Fumio Tanaka† 《Photochemistry and photobiology》1983,37(5):495-502
Formation of singlet charge transfer (heteroexcimer) states in the course of the fluorescence quenching of lumiflavin and riboflavin tetrabutyrate by indole and N-methylindole have been directly observed by means of time-resolved absorption spectral measurements using a picosecond laser photolysis method. Similar transient spectra have been observed also in the case of a flavoenzyme, D-amino acid oxidase. 相似文献
3.
Jun-ichi KawakamiMitsuhiro Takeba Ikuyo KamiyaNoboru Sonoda Akiya Ogawa 《Tetrahedron》2003,59(34):6559-6567
Highly regioselective thioformylation of terminal acetylenes with thiols and carbon monoxide has been developed by the use of rhodium(I) complexes as the catalyst: formyl and thio groups are introduced into the terminal and inner positions of acetylenes, respectively. The thioformylation is performed in the presence of a catalytic amount of rhodium(I) complexes, such as RhH(CO)(PPh3)3, RhCl(PPh3)3, and RhCl(CO)(PPh3)2, under the pressure of CO (3 MPa) at 120°C in CH3CN to provide β-thio-α,β-unsaturated aldehydes in good yields. This thioformylation can be applied to a variety of terminal acetylenes and aromatic thiols. A mechanistic proposal includes the formation of the rhodium sulfide complex as the key species. 相似文献
4.
The heat of immersion in water was measured at 25°C for three iron(III) oxides using a twin-type microcalorimeter. One of the samples was commercial α-Fe2O3 (sample C) and the other two (samples M and F) were prepared by calcining magnetite and iron(III) hydroxide in air at various temperatures, Tp, from 300 to 700°C. The samples were evacuated at outgassing temperature, To, between room temperature and 500°C at a pressure of 1 × 10?2?2.7 × 10?2N m?2 for 6 h. The heat of immersion, hi(J m?2), of samples C and M increased with an increase in To and showed the maximum hi at To =400°C, while sample F did not show the maximum up to To =500°C. The systematic correlation was not observed between hi and Tp of sample F. The heat of reproduction of the surface hydroxyl group on sample F was approximately estimated as 6.6 × 104 J mole?1 H2O. 相似文献
5.
Tadao Ishii Takeshi Tsuchida Ryusaburo Furuichi Hiroshi Haga Kazuhiko Kudo 《Thermochimica Acta》1982,53(1):89-103
The chlorination processes of fly ash and bauxite in the presence of carbon were studied by means of a gas-flow type DTA, X-ray analysis and SEM observation, and the reactivity of Al-compounds as their constituents was compared. In the case of fly ash, the exothermic peak due to the formation of AlCl3 (mainly) and FeCl3 appeared at about 790–920°C. The reactivity of Al estimated from the DTA peak temperature depended on the particle size, carbon content and preparation temperature of fly ash, and was much lower than that of bauxite. Fractional conversion of Al was about 60–70%, when fly ash (?300 mesh) was heated up to 900°C in Cl2 at 5°C min?1 of heating rate. In the case of bauxite, two exothermic peaks due to the chlorination of Fe and Al appeared at about 270 and 490°C, respectively. The chlorination of Al was completed at 550°C under the above conditions. 相似文献
6.
Yuki Sato Dr. Shin-ichi Kawaguchi Dr. Akihiro Nomoto Prof. Dr. Akiya Ogawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(9):2295-2302
Bis-phosphanated compounds are regarded as the most ubiquitous privileged ligand structures in transition-metal catalysis. The development of highly atom economical reactions is of great importance for their syntheses because less atom economical methods often require complicated purification procedures under inert atmospheres to remove excess starting materials and byproducts. Herein, the photoinduced addition reactions of diphosphane monosulfides bearing PV(S)−PIII single bonds to alkenes is disclosed. These reactions require only equimolar amounts of the diphosphane monosulfide relative to the alkene and facilitate highly selective introduction of two different types of phosphorus-containing groups, such as thiophosphoryl and phosphanyl groups, into a variety of alkenes without any catalyst, base, or additive. 相似文献
7.
Despite the fact that many transition-metal-catalyzed reactions of organosulfur compounds with internal alkynes are ineffective, cobalt carbonyl (Co2(CO)8) is an excellent catalyst for carbonylative cyclization of internal alkynes with carbon monoxide. When Co2(CO)8-catalyzed reactions of internal alkynes with organic thiols are conducted in acetonitrile under 4 MPa pressure of carbon monoxide, thiolative lactonization of internal alkynes successfully takes place with incorporation of two molecules of CO. This carbonylation provides a useful tool to prepare the corresponding α,β-unsaturated γ-thio-γ-lactones (butenolide derivatives) in good yields. In the cases of unsymmetrical alkynes, such as 2-octyne and 6-methyl-2-heptyne, the thiolative lactonization proceeds with moderate regioselectivity to give the butenolide derivatives on which the carbonyl group preferentially bonds to the less hindered acetylenic carbon. Mechanistic pathways about the present thiolative lactonization are also discussed. 相似文献
8.
Kuniaki Marui Yuuki Higashiura Shintaro Kodama Suguru Hashidate Akihiro Nomoto Shigenobu Yano Michio Ueshima Akiya Ogawa 《Tetrahedron》2014
The oxidation of alcohols using catalytic amounts of metal complexes is highly attractive from the viewpoint of green chemistry principles. However, examples of metal complex-catalyzed oxidations of alcohols with O2 using water as the solvent are still rare, and precious metals, high-pressure O2 or air, and a stoichiometric amount of base are often required. In this study, it was found that an oxovanadium-4,4′-t-Bubpy (4,4′-di-tert-butyl-2,2′-bipyridyl) complex exhibited high catalytic activity in the oxidation of benzhydrols under an atmosphere of O2 in water as the sole solvent. Interestingly, this catalytic oxidation method could be applied to the gram-scale aerobic oxidation of alcohols in water under the atmosphere. 相似文献
9.
Masahito Sekiguchi Hiromichi Tanaka Noriaki Takami Akiya Ogawa Ilhyong Ryu Noboru Sonoda 《Heteroatom Chemistry》1991,2(3):427-430
The reduction of elemental selenium by samarium diiodide led to selective formation of selenolate anion species (Se2− and Se22−), the alkylation of which provided dialkyl selenides and diselenides, respectively, in excellent yields. 相似文献
10.
Front Cover: Construction of a Triangle‐Shaped Trimer and a Tetrahedron Using an α‐Helix‐Inserted Circular Permutant of Cytochrome c555 (Chem. Asian J. 10/2018) 下载免费PDF全文