Free radical mechanism in olefin isomerization. Isomerization of (Z)-but-2-ene and (Z)-[1,2-2H2]ethylene over siloxene

Abstract

Isomerization of (Z)-but-2-ene and (Z)-[1,2-²H₂]ethylene over siloxene has been studied. The isomerization of (Z)-but-2-ene gives (E)-but-2-ene as sole product and the double bond migration reaction does not proceed. The isomerization of (Z)-[1,2-²H₂]ethylene gives (E)-[1,2-²H₂]ethylene and scrambling of deuterium atoms does not occur. Both the radical species on siloxene and the butene isomerization activity sharply increase with the heat treatment temperature of siloxene. Free radical mechanisms for isomerizations are proposed.