Intramolecular hydrogen isotope effect in the pyrolysis of diethyl carbonate-1,1,1,2,2-d5

The thermal unimolecular decomposition of diethyl carbonate-1,1,1,2,2-d₅ has been examined in the high-pressure-limiting region. The observed chemistry is consistent with a simple, competitive two-channel model: The intramolecular isotope effect k_H/k_D has been determined, and the relative Arrhenius parameters for the two channels are given by over the temperature range of 540–620 K. These Arrhenius parameters predict an isotope effect k_H/k_D = 5.4 at 300 K.