Abstract
Atmospheric oxidation of methyl propanoate (MP) by the OH radical has been performed using density functional theory (BMK, BBIK) and ab initio (MP2, CBS-QB3) calculations. The thermodynamic and kinetic parameters are calculated. Three channels have been discussed. These reactions occur through low energy barriers of 3.2-4.3 kcal/mol. The energy barriers increase in the order < mu < at CBS-QB3. However, BMK shows slightly different order. Rate constants and branching ratios reveal that the H-abstraction from C is as the dominant reaction over the whole temperature range of 200-300 K, with a competition from C channel at lower temperature. The BB1K data reproduce the available experimental rate constant.