Thermal [1,5] Hydrogen Sigmatropic Shifts in cis,cis-1,3-Cyclononadienes Probed by Gas-Phase Kinetic Studies and Density Functional Theory Calculations.
The kinetics of gas-phase thermal [1,5] hydrogen shifts interconverting the five isomeric mono-deuterium-labeled cis, cis-1,3-cyclononadienes have been followed at four temperatures from 240 to 287 °C. The activation parameters found were E = 37.1 ± 0.8 kcal/mol, log A = 11.6 ± 0.3, ΔH† = 36.0 ± 0.8...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 46; pp. 14854 - 14863 |
|---|---|
| Autores principales: | , , , |
| Formato: | Artículo |
| Publicado: |
American Chemical Society
11/22/2006
|
| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=23419916&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 23419916 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 11/22/2006 vid: 128 iid: 46 pid: 997 pub: American Chemical Society artinfo: ui: 23419916 10.1021/ja065656s ppf: 14854 ppct: 9 formats: tig: atl: Thermal [1,5] Hydrogen Sigmatropic Shifts in cis,cis-1,3-Cyclononadienes Probed by Gas-Phase Kinetic Studies and Density Functional Theory Calculations. aug: au: Baldwin, John E. Raghavan, Anuradha S. Hess Jr., B. Andes Smentek, Lidia affil: Departments of Chemistry, Syracuse University, Syracuse, New York 13244 Vanderbilt University, Nashville, Tennessee 37235 Institute of Physics, Nicolaus Copernicus University, 87-100 Toruń, Poland su: Chemical kinetics Deuterium Density functionals Isomerization Functional analysis Isomerism sug: subj: Chemical kinetics Deuterium Density functionals Isomerization Functional analysis Isomerism ab: The kinetics of gas-phase thermal [1,5] hydrogen shifts interconverting the five isomeric mono-deuterium-labeled cis, cis-1,3-cyclononadienes have been followed at four temperatures from 240 to 287 °C. The activation parameters found were E = 37.1 ± 0.8 kcal/mol, log A = 11.6 ± 0.3, ΔH† = 36.0 ± 0.8 kcal/mol, and ΔS† = -9.0 ± 0.3 eu. Density functional theory based calculations have provided geometries and energies for the ground-state cyclononadiene conformational isomers, for the transition states linking one to another, and for the transition states for [1,5] hydrogen shifts responsible for isomerizations among the five labeled dienes. A generalized formulation of the Winstein-Holness equation is presented and applied to the complex system, one that involves 11 ground-state conformers, 10 transition states separating them, and five transition states for [1,5] hydrogen shifts. The value for the empirical Ea derived from calculated mole fractions of ground-state conformers and calculated energies for specific ground-state conformers and [1,5] hydrogen shift transition structures was 37.5 kcal/mol, in excellent agreement with the experimentally obtained activation energy. The significance of conformational options in various ground states and transition structures for the [1,5] hydrogen shifts is considerable, an inference that may well have general applicability. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2006 holdings: @attributes: islocal: N |
|---|