On the other hand, the barrier for β-hydrogen elimination is much higher than those for elimination, with kfwd lower than 1.93x10 -10 for the R4b step at T= 25-300 °C. Consequently, the low rate constants make it unlikely for the β-hydrogen elimination to be a valid pathway for ITG decomposition at low temperatures. Finally, the adduct release reactions (R1c/R2c/R3c) occur without a transition state barrier. In the kinetic model, these reactions are modeled as instantaneous equilibrium reactions as the lack of a barrier would make them much quicker than the other reactions.