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Selenium‐catalyzed thermal isomerization of cis‐2‐styrylfuran and cis‐2‐styrylthiophene
Author(s) -
Scarlata Giuseppe,
Torre Michele
Publication year - 1976
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570130609
Subject(s) - isomerization , chemistry , catalysis , reactivity (psychology) , activation energy , selenium , reaction rate constant , medicinal chemistry , thiophene , atmospheric temperature range , photochemistry , kinetics , organic chemistry , thermodynamics , medicine , physics , alternative medicine , pathology , quantum mechanics
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.