Ab initio calculation on the mechanism for the reaction CH3+OClO

The three possible production channels for the reaction CH3 + OClO are stud ied by ab initio calculations. Geometries of the reactants, products, inter mediates and transition states are optimized at the UMP2(full)/6 - 31G(d,p) level. The corresponding vibrational frequencies are calculated at the sam e level. Based on the total energies calculated at the G2MP2 level, the rea ction heats and activation barriers are obtained. The computation results s how that the production channel HOCl + H2CO is the most feasible pathway, w hich is exothermic by 443.80 kJ . mol(-1). It suggests that an activated in termediate is first formed through a barrierless process in this reaction, and the intermediate will dissociate to HOCl + H2CO via a five-center trans ition state.