Ab initio kinetics of OH-initiated oxidation of cyclopentadiene

This work computationally reports a detailed kinetic mechanism of the OH-initiated reaction of 1,3-cyclopentadiene (CPDN), a key intermediate during the oxidation processes of aromatic and acyclic compounds, in the wide range of T = 298 - 2000 K and P = 0.76 - 7600 Torr. The temperature-and pressure-dependent behaviors of the title reaction were simulated using the RRKM-based Master Equation rate model on the potential energy profile explored at M06-2X/aug-cc-pVTZ level. The model reveals that the OH-addition on C alpha of CPDN to form adduct 5hydroxycyclopent-2-en-1-yl dominates at low temperatures (e.g., T <=& nbsp;1000 K at 760 Torr), while the direct H abstraction channels from C alpha and C-beta of CPDN become predominant at high temperatures (e.g., T > 1000 K at 760 Torr). The observed U-shaped temperature-dependent behaviors and slightly positive pressure dependence at low temperatures (e.g., T <=& nbsp;& nbsp;1000 K & P = 760 Torr) of the total rate constants are described by a double modified Arrhenius expression as ktot(T) = 1.61 x 10(9) x T-(6.67) x exp[-1627.6 K/T] + 3.87 x 10(-17) x T-2.08 x exp[-2519.9 K/T] (cm(3)/molecule/s) for T = 298 - 2000 K & P = 760 Torr. Discrepancies in k(total)(T, P) between the early calculations and measurements in low-and high-temperature regimes are also resolved. Also, the thermodynamically consistent mechanism is provided to advance modeling and simulation of any CPDN-related applications.

Automated summary

This work computationally reports a detailed kinetic mechanism of the OH-initiated reaction of 1,3-cyclopentadiene (CPDN) in different temperatures and pressures. The study provides a thermodynamically consistent mechanism and resolves discrepancies between calculations and experiments.