ISSN:
1434-193X
Schlagwort(e):
S Heterocycles
;
Cyclic oligosulfides
;
Pentathiepanes
;
Conformational analysis
;
Sulfuration
;
Ring inversion
;
Chemistry
;
General Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
-Acenaphtho[1,2-a]acenaphthylene (1) was sulfurated with elemental sulfur to give a pentathiepane derivative (2). A dynamic NMR spectrum analysis revealed that the two naphthalene rings of 2 are chemically nonequivalent up to 100 °C. The pentathiepane ring of 2 was shown to adopt a chair conformation both in solution and crystals. In accordance with the NMR spectrum analysis, the sulfuration of 5-phenylacenaphtho[1,2-a]acenaphthylene (12) gave a pair of conformers (16a and 16b), which were isolated in pure form. The Friedel-Crafts acetylation of 2, followed by dithioacetalization with 1,2-ethanedithiol, also gave a pair of isolable conformers (18a and 18b). These two pairs of conformers isomerized, as a result of the ring inversion, to each other in solution at room temperature in the first-order kinetics. The activation parameters for this process, Ea, ΔH#, and ΔS#, were determined. Based on the experimental observations, a probable mechanism for the inversion process is proposed.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
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