15094-05-0Relevant academic research and scientific papers
Relative Thermodynamic Stabilities of 3-Ethylidenecyclohexenes and Isomeric Ethylcyclohexadienes
Taskinen, Esko,Nummelin, Kari
, p. 11693 - 11698 (2007/10/02)
The relative thermodynamic stabilities of the E and Z forms of 3-ethylidenecyclohexene, 1-ethyl-1,3-cyclohexadiene, 2-ethyl-1,3-cyclohexadiene and 1-ethyl-1,4-cyclohexadiene were determined by t-BuOK catalyzed chemical equilibration in DMSO solution.From the variation of the equilibrium composition with temperature the enthalpy, entropy and Gibbs energy differences between the isomeric species were evaluated.The ethylidenecyclohexenes were found to be the most abundant species at thermodynamic equilibrium, owing to their 9-12 kJ mol-1 lower enthalpy values.The entropy term, however, favors the cyclohexadienes by 7-11 J K-1 mol-1.
Rotational Barriers of Vinyl-Substituted Olefines
Doering, William von E.,Roth, Wolfgang R.,Bauer, Frank,Boenke, Martin,Breuckmann, Rolf,et al.
, p. 1461 - 1470 (2007/10/02)
For the vinyl-substituted olefines 1-14 activation parameters for the geometrical isomerisation have been determined in the gas-phase.By comparison of these barriers with the corresponding ones of the isolated double bonds, each corrected by the contribution of the steric energy to the ground and transition state, a value of 13.5 +/- 1.1 kcal mol-1 for the allyl stabilisation energy (ASE), defined as replacement of alkyl by vinyl, has been derived.
