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61.
Solid microparticles of several different insoluble organic compounds were mechanically immobilized on the surface of graphite
electrodes and immersed into a liquid electrolyte in order to study their electrochemical reactions. Cyclic staircase voltammetry
and square-wave voltammetry were used. Quinhydrone was found to be a stable intermediate in the reversible redox reaction
of solid quinone and hydroquinone on the electrode surface. The reaction occurs on the surface of the solid particle which
is in contact with water. Indigo can be reduced to leucoindigo and oxidized to dehydroindigo in two separate reversible redox
reactions. In strongly basic medium indigo dissolves in water upon electroreduction. A hydroacridine radical was detected
as a stable intermediate in the electrochemically irreversible redox reaction of acridine and dihydroacridine. Famotidine
can be electrooxidized and the product of this reaction can be electroreduced in two separate chemically irreversible reactions.
Probucol is oxidized to a semiquinone radical which can be re-reduced in an electrochemically irreversible redox reaction.
Propyl- thiouracil can be also oxidized to an unknown product which can be re-reduced in a chemically reversible, but slow
solid state surface redox reaction. Reductions of solid thionicotinoylanilide and nicotinoylanilide are totally irreversible.
Received September 22, 1998. Revision March 19, 1999. 相似文献
62.
me3Si? CCl2?Sime2Cl (me ? CH3) läßt sich mit n-buLi (bu ? C4H9) bei–100°C (Lösungsmittel THF/Äther) in me3Si? CCl(Li)? Sime2Cl a überführen. das mit meJ me3Si? CClme? Sime2Cl bildet. Wird a in Abwesenheit eines Abfangreagenzes langsam erwärmt, so bildet sich unter Abspaltung von LiCl (Cl aus der SiCl-Gruppe) über eine reaktive Zwischenstufe des Bicyclobutans b . Die Struktur von b ist durch NMR-Untersuchung, Röntgenstrukturanalyse und Abbaureaktionen gesichert. Mit HBr bzw. CH3OH werden die Si? C-Bindungen der Dreiringe in b gespalten, so daß sich me3Si? CH2? C(Sime2X)2Sime3 (X ? Br, OCH3) bildet. Formation of Organosilicon Compounds. 85. Formation, Reactions, and Structure of 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butane me3Si? CCl2? Sime2Cl (me ? CH3) with n-buLi (bu ? C4H9) at –100°C (solvent: THF/ether) yields me3Si? CCl(Li)? Sime2Cl a , which forms me3Si? CClme? Sime2Cl with meI. By warming a slowly in absence of any trapping reagent the bicyclobutane b is obtained via a reactive intermediate under elimination of LiCl (Cl from the SiCl group). The structure of b is established by nmr investigations, X-ray structure determination and chemical derivatisation. 相似文献
63.
Zusammenfassung Das früher beschriebene1 Succinylzellulose-Papier wird als Ionenaustauscher zur weiteren papierchromatischen Trennung von Basengemischen verwendet. Getrennt wurden die Alkaloide der Morphingruppe und deren Abwandlungsprodukte, ferner die Alkaloide der Strychnin-, der Tropin-, der Cocaingruppe und andere Alkaloide.
Summary The succinyl-cellulose paper described previously1 is used as ion exchanger for additional paper chromatographic separations of mixtures of bases. Separations were accomplished of the alkaloids of the morphine group and their modification products, and also of the alkaloids of the strychnine-, tropine- and cocaine groups and other alkaloids.
Résumé On utilise le papier à la succinyl-cellulose déjà décrit1, comme écharigeur d'ions pour d'autres séparations par chromatographie sur papier de mélanges basiques. On a séparé ainsi les alcaloïdes du groupe de la morphine et leurs produits d'évolution, et en outre, les alcaloïdes des groupes de la strychnine, de la tropine et de la cocaïne et d'autres alcaloïdes.相似文献
64.
The structures of aggregates formed in aqueous solutions of an anionic surfactant, sodium dodecyl sulfate (SDS), with the addition of a cationic hydrotropic salt, p-toluidine hydrochloride (PTHC), have been investigated by small angle neutron scattering (SANS). The SANS spectra exhibit a pronounced peak at low salt concentration, indicating the presence of repulsive intermicellar interactions. Model-independent real space information about the structure is obtained from a generalized indirect Fourier transformation (GIFT) technique in combination with a suitable model for the interparticle structure factor. The interparticle interaction is captured using the rescaled mean spherical approximation (RMSA) closure relation and a Yukawa form of the interaction potential. Further quantification of the geometrical parameters of the micelles was achieved by a complete fit of the SANS data using a prolate ellipsoidal form factor and the RMSA structure factor. The present study shows that PTHC induces a decrease in the fractional charge of the micelles due to adsorption at the micellar surface and consequent growth of the SDS micelles from nearly globular to rodlike as the concentration of PTHC increases. 相似文献
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Extension of the Chain Length of P2(SiMe3)4 by Reaction with LiBu The first steps of the reaction of P2(SiMe3)4 1 with LiBu in THF, which finally yields Li3P7 among other P-rich phosphides while P(SiMe3)3 and LiP(SiMe3)2 are simultaneously split off, were investigated by means of 31P-NMR spectroscopy. At ?20°C first of all one Si? P bond is cleaved generating Li(Me3Si)P? P(SiMe3)2 2 as well as BuSiMe3. Subsequently 2 forms Li(Me3Si)P? P(SiMe3)? P(SiMe3)2 5 and LiP(SiMe3)2 4 in equimolar ratios. This clearly demonstrates that both compounds are generated in one single reaction step. This behaviour is caused by the different basicity of the respective P-atoms in 2 , which necessarily results in a multicentered mechanism. 相似文献