Effiziente Photoreduktion von Triazinen mit aliphatischen Aminen

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Aliphatic amines are used as powerful electron donators in electrontransfer reactions of electronically excited aromatic amines. In triazines the LUMO energy is decreased compared to benzene, therefore these electron-poor compounds are easily reduced and the corresponding radical anions are stabilized. Aromatic 1,2,4-triazines and 1,2,3-triazines were irradiated in aprotic triethylamine and protic diethylamine as well as in dimethylammonium dimethylcarbamate (Dimcarb). The reduction products of 1,2,4-triazines are mostly dihydroderivates (resembling the products of Birch-reduction) and products of ring contraction. Ringcontractions in turn require the transfer of four reduction equivalents and may involve the loss of ammonia. The photolysis of the two investigated 1,2,3-triazines causes loss of dinitrogen. In one case the irradiation furnishes the product after loss of dinitrogen, in an other case the irradiation amount three products of fragmentation, however also a pyrazol. This demonstrates that the strong reducing conditions allow to override this fragmentation to a small extent. All trazine conversions depend on the nature of the amine, on amine concentration an on light intensity. The reactive state of the investigated 1,2,4-triazines may be the lowest triplet, as confirmed by phospherescence and T-T absorption spectroscopy.
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Dokumententyp:
Wissenschaftliche Abschlussarbeiten » Dissertation
Fakultät / Institut:
Fakultät für Chemie
Dewey Dezimal-Klassifikation:
500 Naturwissenschaften und Mathematik » 540 Chemie
Stichwörter:
fragmentation, ringcontraction, light-induced reduction, dihydroderivates, quantum yield, organic photochemistry, T-T absorption spectroscopy, aromatic triazines
Beitragende:
Prof. Dr. Döpp, Dietrich [Betreuer(in), Doktorvater]
Prof. Dr. rer. nat. Tausch, Michael [Gutachter(in), Rezensent(in)]
Sprache:
Deutsch
Kollektion / Status:
Dissertationen / Dokument veröffentlicht
Datum der Promotion:
19.06.2002
Dokument erstellt am:
19.06.2002
Dateien geändert am:
20.10.2006
Medientyp:
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