Gas-Phase Kinetics and Activation Parameters for Thermal [1,5] Hydrogen Shifts Interconverting Monodeuterium- Labeled 1,3-Cycloheptadienes
作者:John E. Baldwin、Anuradha S. Raghavan
DOI:10.1021/jo040238w
日期:2004.11.1
The kinetics of thermal equilibrations among monodeuterium-labeled 1,3-cycloheptadienes in the gas phase followed from 154 to 190 °C provide activation parameters for the [1,5] shift of a single hydrogen: Ea = (27.5 ± 0.9) kcal/mol and log A = 9.9 ± 0.4. These activation parameters imply a comparatively low Ea barrier balanced by demandingly specific geometric constraints, for ΔS⧧ (170 °C) = −16 e
从154到190°C的气相中单氘标记的1,3-环庚二烯之间的热平衡动力学为单个氢的[1,5]位移提供了激活参数:E a =(27.5±0.9)kcal / mol,log A = 9.9±0.4。这些激活参数意味着相对低é一个屏障由吃力特定几何约束平衡,对Δ小号⧧(170℃)= -16 EU