| Abstract: | 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. |
