Thermochemistry and kinetics of isobutanol oxidation by the OH radical

Thermochemistry and kinetics of isobutanol oxidation by the OH radical have been studied using density functional theory (BMK, BBIK) and ab initio (MP2, CBS-QB3) calculations. Four channels have been discussed, all of them are exothermic. These reactions occur through low energy barriers of −1.0–2.64 kcal/mol. The energy barriers increase in the order β < α < γ < OH at BB1K, MP2, and CBS–QB3. However, BMK shows slightly different order. Rate constants and branching ratios show H-abstraction from Cα as the dominant reaction over the whole temperature range of 200–2000 K, with a competition from Cβ channel at lower temperature up to 600 K. The BB1K data reproduce the available experimental total rate constant for isobutanol oxidation by the OH radical.