Theoretical Studies on the Mechanisms and Dynamics of OH Radical with (CH₃)₃COOH and (CH₃)₂CHOOH

A dual-level direct dynamic method is employed to study the reaction mechanism of hydroxyl radical with (CH₃)₃COOH and (CH₃)₂CHOOH. Eight hydrogen abstraction channels are found for title reactions. The energy paths are optimized at the BH&H-HLYP/6-311G­(d,p) level, and the energy profiles are further refined by interpolated single-point energies method at the CCSD­(T) and QCISD­(T) theories. Rate coefficients for the reactions of the OH with (CH₃)₃COOH/(CH₃)₂CHOOH are computed by the canonical variational transition-state theory with the small-curvature tunneling correction between 200 and 2000 K. The Arrhenius expressions <i>k</i>₁ (T) = 1.49 × 10^–26 T^4.71 exp­(1981.92/T) and <i>k</i>₂ (T) = 1.58 × 10^–20 T^3.32 exp­(210.59/T) over 200–2000 K are obtained