Thermodynamics of Vinyl Ethers. 31. Isomer Equilibria in Some Six- and Seven-Membered Cyclic Dienes

Article abstract of DOI:10.1021/jo00224a038

The relative thermodynamic stabilities of 1,3-cyclohexadiene and 1,4-cyclohexadiene, together with a number of their alkoxy and other derivatives and some related seven-membered cyclic dienes, have been determined by chemical equilibration in Me2SO and cyclohexane solution at various temperatures.The values of the thermodynamic parameters ΣG^<*>, ΔH^<*>, and ΔS^<*> for the isomerization processes involved are discussed and show clearly that the apparently conjugated diene system of 1,3-cyclohexadiene is devoid of conjugation, contrary to that of 1,3-cycloheptadiene.