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41.
Masanori Sakamoto Takashi Tachikawa Sung Sik Kim Mamoru Fujitsuka Tetsuro Majima 《Chemphyschem》2007,8(11):1701-1706
The association behavior of the dyes 5(6)-carboxyfluorescein and nitrilotriacetic acid (NTA)-modified 5(6)-carboxyfluorescein (F-NTA) in a poly(vinyl alcohol) (PVA) film and in a PVA film containing metal nanoparticles is investigated. Well-dispersed gold nanoparticles (AuNps) and Ni(II)-adsorbed AuNps are formed in the PVA film using in situ photochemical fabrication method. 5(6)-carboxyfluorescein and F-NTA are doped into the films. The F-NTA forms an H-aggregate in the PVA film containing Ni(II)-adsorbed AuNps. It is suggested that the interaction between NTA and Ni(II) adsorbed on the AuNps promotes the formation of the H-aggregate. 相似文献
42.
Bo Jiang Lixing Yang Yong Zhou Guanglin Huang Libin Lin 《Radiation Physics and Chemistry》2002,63(3-6):469-473
The radiation-induced hybrid polymerization in the presence of the N-alkoxypyridinium salt having relatively stable nonnucleophilic anion (PF6−) has been investigated in the paper. Based on the analysis of experimental data and the GPC spectrum, the onium salts not only oxidize -alkoxyalkyl radicals, produced from IBVE in dichloromethane by irradiation, to the corresponding cations, but also give nonnucleophilic anions PF6− for the polymerization system. The experimental results clearly demonstrate that free radical and cationic polymerization mechanisms occurred simultaneously in IBVE/EMP+PF6−/CH2Cl2 systems on irradiation with γ-ray. 相似文献
43.
Yoshitaka Uenoyama Takahide Fukuyama Keisuke Morimoto Osamu Nobuta Hidefumi Nagai Ilhyong Ryu 《Helvetica chimica acta》2006,89(10):2483-2494
The carbonylation of alkanes 1 under radical‐reaction conditions was examined by using ethynyl triflone A as the unimolecular chain‐transfer (UMCT) reagent. Good to moderate yields of ethynyl ketones 2 were prepared by means of this three‐component coupling reaction. Higher CO pressures as well as lower concentrations of triflone A improved the efficiency of the reaction over the direct addition, the latter leading to alkylated ethynes 3 . In contrast to the reaction with A , the reaction of cyclohexane ( 1a ) with allyl triflone B (= ethyl 2‐methylene‐3‐[(trifluoromethyl)sulfonyl]propanoate) in the presence of CO gave a mixture of carbonylation products, including 8a formed from two molecules each of cyclohexane, CO, and allyl triflone B . 相似文献
44.
E. V. Tretyakov S. E. Tolstikov G. V. Romanenko Yu. G. Shvedenkov R. Z. Sagdeev V. I. Ovcharenko 《Russian Chemical Bulletin》2005,54(9):2169-2181
A new approach to the synthesis of polyfunctional pyrazolyl-substituted nitronyl nitroxides was developed based on the presynthesized
pyrazole derivatives prepared by 1,3-dipolar cycloaddition. The structures of the resulting mono-and biradicals were confirmed
by X-ray diffraction.
Dedicated to Academician A. L. Buchachenko on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2105–2116, September, 2005. 相似文献
45.
Jack H. Lunsford 《Angewandte Chemie (International ed. in English)》1995,34(9):970-980
One of the great challenges in the field of heterogeneous catalysis is the conversion of methane to more useful chemicals and fuels. A chemical of particular importance is ethene, which can be obtained by the oxidative coupling of methane. In this reaction CH4 is first oxidatively converted into C2H6, and then into C2H4. The fundamental aspects of the problem involve both a heterogeneous component, which includes the activation of CH4 on a metal oxide surface, and a homogeneous gas-phase component, which includes free-radical chemistry. Ethane is produced mainly by the coupling of the surface-generated CH radicals in the gas phase. The yield of C2H4 and C2H6 is limited by secondary reactions of CH radicals with the surface and by the further oxidation of C2H4, both on the catalyst surface and in the gas phase. Currently, the best catalysts provide 20% CH4 conversion with 80% combined C2H4 and C2H6 selectivity in a single pass through the reactor. Less is known about the nature of the active centers than about the reaction mechanism; however, reactive oxygen ions are apparently required for the activation of CH4 on certain catalysts. There is spectroscopic evidence for surface O? or O ions. In addition to the oxidative coupling of CH4, cross-coupling reactions, such as between methane and toluene to produce styrene, have been investigated. Many of the same catalysts are effective, and the cross-coupling reaction also appears to involve surface-generated radicals. Although a technological process has not been developed, extensive research has resulted in a reasonable understanding of the elementary reactions that occur during the oxidative coupling of methane. 相似文献
46.
Guillermina Burillo Takeshi Ogawa Jimmy S. Hwang 《Journal of polymer science. Part A, Polymer chemistry》1992,30(10):2159-2164
A number of diacetylene containing acrylate and methacrylates have been synthesized and the interaction between their propagating radicals and the diacetylene groups was studied by ESR spectroscopy. In the case of polymerization at 70°C using AIBN as an initiator, the propagating radicals of methacrylates are temporarily trapped with the diacetylenes with rapid exchange of the electron, thus showing strong signals of the propagating radicals. Gamma irradiation of the frozen state produces a blue color in samples, and the ESR signals were found to be those of uninteracted acrylate and methacrylates. From a comparison of spectral widths, there seems to exist an intramolecular interaction between the radicals and the diacetylene group at the frozen state. © 1992 John Wiley & Sons, Inc. 相似文献
47.
R. Stahl 《Chromatographia》1993,37(5-6):300-302
Summary The determination of chloride and perchlorate by non-suppressed ion chromatography in aqueous process solutions containing a high sulfate background is described. The method is reliable and fast. The sensitivity for perchlorate is lower than for other anions like nitrate, nitrite and chlorate. The detection limits are about 0.3 g/ml with linear calibration curves within a concentration range from 1 to 50 g/ml. 相似文献
48.
《中国化学快报》2020,31(6):1535-1539
Chlorinated organic pollutants(COPs) have caused serious contaminants in soil and groundwater,hence developing methods to remove these pollutants is necessary and urgent.By a simple hydrothermal method,we synthesized the bimetallic iron-nickel sulfide(FeNiS) particles which exhibited excellent catalytic property of COPs removal.FeNiS was chosen as the peroxydisulfate(PDS) activator to removal COPs including 4-chlorophenol(4-CP),1,4-dichlorophenol(1,4-DCP) and 2,4,6-trichlorophenol(2,4,6-TCP).The results show that FeNiS can efficiently activate PDS to produce sulfate radical(SO_4~(·-)) which plays major role in the oxidative dechlorination and degradation due to its strong oxidizing property and the ability of producing hydroxyl radicals(~·OH) in the alkaline condition.Meanwhile,the Cl-abscised from COPs during the dechlorination can turn into the chlorine radicals and enhance the degradation and cause further mineralization of intermediate products.This bimetallic FeNiS catalyst is a promising PDS activator for removal of chlorinated organics. 相似文献
49.
Electrochemical Oxidation of Quercetin 总被引:1,自引:0,他引:1
《Electroanalysis》2003,15(22):1745-1750
The mechanism of electrochemical oxidation of quercetin on a glassy carbon electrode has been studied using cyclic, differential pulse and square‐wave voltammetry at different pH. It proceeds in a cascade mechanism, related with the two catechol hydroxyl groups and the other three hydroxyl groups which all present electroactivity, and the oxidation is pH dependent. Quercetin also adsorbs strongly on the electrode surface; and the final oxidation product is not electroactive and blocks the electrode surface. The oxidation of the catechol 3′,4′‐dihydroxyl electron‐donating groups, occurs first, at very low positive potentials, and is a two electron two proton reversible reaction. The hydroxyl group oxidized next was shown to undergo an irreversible oxidation reaction, and this hydroxyl group can form a intermolecular hydrogen bond with the neighboring oxygen. The other two hydroxyl groups also have an electron donating effect and their oxidation is reversible. 相似文献
50.
B. L. Tumanskii 《Russian Chemical Bulletin》1996,45(10):2267-2278
The results of ESR spectroscopic studies of radical reactions of fullerenes are presented. Reactivities of radicals of various chemical natures with respect to C60 and C70, delocalization of the unpaired electron in monofullerenyl radicals, and their reactivity are considered. The examples of dynamic effects in the ESR spectra of fullerenyl radicals, associated with the hindered rotation of the attached radicals, are presented. Characteristic features of the structures of the spin adducts resulting from polyaddition of free radicals to fullerenes and of fullerenyl radicals containing 2-bonded metaIloco mplexes are discussed.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2396–2406, October, 1996. 相似文献