Selenium-catalyzed thermal isomerization of cis-2-styrylfuran and cis-2-styrylthiophene
1976; Wiley; Volume: 13; Issue: 6 Linguagem: Inglês
10.1002/jhet.5570130609
ISSN1943-5193
AutoresGiuseppe Scarlata, Michele Torre,
Tópico(s)Synthesis and Characterization of Pyrroles
ResumoAbstract The rate of selenium catalyzed cis‐trans isomerization of stilbene, 2‐styrylfuran and 2‐styryI‐thiophene in decahydronaphthalene has been studied in the temperature range 170‐190° by gas chromatographic analysis. Rate constants were pseudo first order and gave the following reactivity order: e(.s‐stilbene < cis‐2‐styrylthiophene < cis ‐2‐styrylfuran. In all cases the reaction orders with respect to selenium are temperature dependent. For catalyzed cis‐stilbene isomerization the activation energy is ca. 15 kcal. mole −1 lower than for thermal isomerization. The hypothesis that cis ‐2‐styrylfuran isomerizes through a triplet state is proposed.
Referência(s)