Gas-phase kinetics and activation parameters for thermal 1,5-hydrogen shifts interconverting monodeuterium-labeled 1,3-cyclohexadienes.
Thermal equilibrations among the three possible monodeuterium-labeled 1,3-cyclohexadienes have been followed in the gas phase at temperatures from 254 to 284 degrees C. The temperature-dependent rate constants for the 1,5-shift of a single hydrogen lead to the activation parameters E(a) = (40.1 +/- 0.8) kcal/mol, log A = (12.1 +/- 0.3), and DeltaS = -(6.3 +/- 1.3) e.u. These activation parameters are reconciled with experimental values reported earlier for reactions starting with 1,4-d(2)-cyclohexadiene.
Baldwin
John E
JE
Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA. jbaldwin@syr.edu
Chapman
Bonnie R
BR