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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 33 (1982), S. 83-88 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: A study of the dealloying resistance of noble metal dental alloys.In connection with the development of low gold dental alloys the corrosion resistance of homogeneous gold-palladium-silver-experimental alloys was investigated in a chloride solution. Analogous measurements were made with several noble metal containing intermetallic phases which may be present in dental alloys of more complex composition. The results indicate a high corrosion resistance of the homogeneous gold-palladium-silver-alloys, since their free corrosion potentials are always situated within a region of their anodic polarization curves, where the current density of metal dissolution is extremely low. Within the composition limits of these alloys the substitution of gold by palladium did not reduce the extension of this “region of immunity” in a significant way. Intermetallic phases, however, as present in the systems silver-tin, silver-palladium-tin and silver-palladium-indium show a clearly restricted “region of immunity” and, at the free corrosion potential, are dissolved at a relatively high rate.
    Notes: Im Zusammenhang mit der Entwicklung goldarmer Dentallegierungen wurde in einem Chloridelektrolyten die, Korrosionsbeständigkeit homogener Gold-Palladium-Silber-Modellegierungen untersucht. Analoge Messungen wurden an verschiedenen edelmetallhaltigen intermetallischen Phasen durchgeführt, die in komplizierter zusammengesetzten Dentallegierungen auftreten können. Die Meßergebnisse zeigen, daß die Gold-Palladium-Silber-Legierungen eine hohe Korrosionsbeständigkeit aufweisen, da ihre Korrosionspotentiale durchweg in jenem Bereich ihrer anodischen Stromspannungskurve liegen, in dem die Geschwindigkeit der Metallauflösung extrem klein ist. Die Ausdehnung dieses “Resistenzbereiches” wird nicht wesentlich verkleinert, wenn innerhalb der hier vorgegebenen Grenzen Gold teilweise durch Palladium substituiert wird. Intermetallische Phasen der Systeme Silber-Zinn, Silber-Palladium-Zinn und Silber-Palladium-Indium weisen dagegen einen deutlich eingeschränkten Resistenzbereich auf und werden bereits beim Korrosionspotential vergleichsweise schnell aufgelöst.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 319 (1977), S. 568-572 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Electrochemical Rearrangement of Papaverine and Dimerisation to 12,12′-Bis{2,3,9,10-tetramethoxy-indolo [2,1-a]isoquinolinyl}Preparative anodic oxydation of papaverine [6,7-dimethoxy-1-(3,4-dimethoxybenzyl)isoquinoline] in methanol with the aid of Pt-electrodes yields 12,12′-bis{2,3,9,10-tetramethoxyindolo[2,1-a]isoquinolinyl}.During this process 3 H-atoms are lost per mole papaverine. At first the benzyl-isoquinolinestructure rearranges to 2,3,9,10-tetramethoxy-indolo [2,1-a]isoquinoline, which dimerises by C—C-bonding in position 12. Voltammetric measurements were carried out. 13C-n.m r.-spectroscopic results demonstrate steric hindrance of the two molecule-moieties.
    Notes: Die präparative anodische Oxydation von Papaverin [6,7-Dimethoxy-1-(3,4-dimethoxy-benzyl)isochinolin] in Methanol an Platinanoden führt unter Verlust von 3 Wasserstoffatomen pro Mol zu 12,12′-Bis{2,3,9,10-tetramethoxy-indolo[2,1-a]isochinolinyl}. Hierbei lagert sich die Benzyl-isochinolinstruktur unter Abgabe von 2 H-Atomen zu 2,3,9,10-Tetramethoxy-indolo[2,1-a]isochinolin um, das durch weiteren Verlust je eines Protons und Elektrons am C-Atom 12 dimerisiert. Es wird über voltammetrische Ergebnisse berichtet. 13C-NMR-spektroskopische Messungen weisen auf eine beträchtliche Verdrillung beider Molekülhälften hin.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 81 (1969), S. 292-293 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 8 (1969), S. 281-282 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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