Theoretical Study on the Mechanism of CH + O2 Reaction

A detailed mechanistic study of the CH + O-2 reaction, in which the products are involved, is carried out by means of CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p) + ZPVE computational method to determine a set of reasonable pathways. The reaction is shown to proceed with an exothermic barrierless addition of O-2 to the methylidyne (CH) radical to form intermediate HCOO (a2). The HCOO radical was found to have two dissociation channels, giving products P1 HCO and O radical through the nonplanar transition states, and giving intermediate CO2H (b1) through the planar transition states, in addition to the backward reaction forming the products radical (channel A, B, C, D, E). It is shown that B (HCO + O), E (CO + OH) are the major product channels with a minor contribution from D (CO2 + H), whereas the other channels for are less favorable.