The thermal unimolecular isomerisation of hepta-1,2,6-triene

Abstract

The thermal isomerisation of hepta-1,2,6-triene has been investigated in the temperature range 172·2–218·1° and at pressures in the range 0·5–20 mm. In an “aged” reaction vessel the isomerisation is homogeneous and strictly of the first order and yields only 3-methylenehexa-1,5-diene. The rate constants fit the Arrhenius equation k= 10^9.97 exp (-28,470/RT) sec.^–1. The reaction is almost certainly unimolecular and probably proceeds by a cyclic transition complex, thus representing an example of the Cope rearrangement.