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Burkhard Butschke Maria Schlangen Detlef Schröder Helmut Schwarz 《Helvetica chimica acta》2008,91(10):1902-1915
Mechanistic details for the formation of methane from the title compound as well as the combined elimination of (CH3)2S/CH4 are derived from various mass‐spectrometric experiments including deuterium‐labeling studies and DFT calculations. For the first process, i.e., methane formation, we have identified three competing pathways in which the intact, Pt‐bonded methyl group combines with a H‐atom that originates from a phenyl substituent (ca. 7%), the dimethyl sulfide ligand (ca. 41%), and a methyl group of the diazabutadiene backbone (ca. 52%). In contrast, in the combined (CH3)2S/CH4 elimination, the methane is specifically formed from the Pt‐bound CH3 group and a H‐atom provided by one of the phenyl groups (‘cyclometalation’). 相似文献
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Xiangli Liu Ping Fan Ming Chen Hossam Hefesha GerhardK.E. Scriba Detlef Gabel Alfred Fahr 《Helvetica chimica acta》2010,93(2):203-211
The objective of this study was to investigate drug–membrane interaction by immobilized liposome chromatography (ILC; expressed as lipophilicity index log Ks) and the comparison with lipophilicity indices obtained by liposome/H2O, octan‐1‐ol/H2O, and immobilized artificial membrane (IAM) systems. A set of structurally diverse monofunctional compounds and drugs (nonsteroidal anti‐inflammatory drugs and β‐blockers) were selected in this study. This set of solutes consists of basic or acidic functionalities which are positively or negatively charged at physiological pH 7.4. No correlation was found between log Ks from ILC and lipophilicity indices from any of the other membrane model systems for the whole set of compounds. For structurally related compounds, significant correlations could be established between log Ks from ILC and lipophilicity indices from IAM chromatography and octan‐1‐ol/H2O. However, ILC and liposome/H2O systems only yield parallel partitioning information for structurally related large molecules. For hydrophilic compounds, the balance between electrostatic and hydrophobic interactions dominating drug partitioning is different in these two systems. 相似文献
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Anina Wöhl Dr. Wolfgang Müller Dr. Stephan Peitz Normen Peulecke Dr. Bhaskar R. Aluri Dr. Bernd H. Müller Dr. Detlef Heller Dr. Uwe Rosenthal Prof. Dr. Mohammed H. Al‐Hazmi Dr. Fuad M. Mosa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(26):7833-7842
In this paper we report the results of an extensive experimental kinetic study carried out on the novel ethylene trimerization catalyst system, comprising the chromium source [CrCl3(thf)3] (thf=tetrahydrofuran), a Ph2P‐N(iPr)‐P(Ph)‐N(iPr)H (PNPNH) ligand (Ph=phenyl, iPr=isopropyl), and triethylaluminum (AlEt3) as activator. It could be shown that the initial activity shows a first‐order dependency on the ethylene concentration. Also, a first‐order dependency was found for the catalyst concentration. The initial activity follows a typical Arrhenius behavior with an experimentally determined activation energy of 52.6 kJ mol?1. At elevated temperatures (ca. 80 °C), a significant deactivation was observed, which can be tentatively traced back to a ligand rearrangement in the presence of AlEt3. After a fast initial phase, a pronounced ‘kink’ in the ethylene‐uptake curve is observed, followed by a slow, almost linear, further increase of the total ethylene consumption. The catalyst composition, in particular the ligand/chromium and the cocatalyst/chromium molar ratio, has a strong impact on the catalytic performance of the trimerization of ethylene. 相似文献