Theoretical study of the hydrogen abstraction reaction of CH3OH with NCO

A THEORETICAL STUDY ON THE TWO REACTIONS OF CH3OH WITH NH(3Σ-) AND NH2(2B1)

The CH 3 OH with NH (3Σ-) and NH 2(2 B 1) reactions are key processes in methanol combustion. Optimized geometries and frequencies have been computed at UMP2 and UB3lYP levels. Energy values are improved using UQCISD(T), G3MP2, and BMC-CCSD methods using UMP2/6-311+G(d,p) optimized structures. For the two reactions, hydrogen abstraction and S N 2 substitution mechanisms have been investigated. Due to high barriers, the S N 2 substitution pathways play negligible roles. Methyl hydrogen abstraction channels are preferred to that of hydroxyl hydrogen, and the final products of NH 3 with CH 2 OH are major.

AB INITIO INVESTIGATIONS OF THE RADICAL–RADICAL REACTION: N (4S) + NCO (X2Π)

The reaction of N (4S) radical with NCO (X2Π) radical has been studied theoretically using density functional theory and ab initio quantum chemistry method. The triplet electronic state [ N 2 CO ] potential energy surface (PES) is calculated at the G3B3 and CCSD(T)/aug-cc-pVDZ//B3LYP/6-311++G(d,p) levels of theory. All the energies of the transition states and isomers in the pathway RP1 are lower than that of the reactants; the rate of this pathway should be very fast. Thus, the novel reaction N + NCO can proceed effectively even at low temperatures and it is expected to play a role in both combustion and interstellar processes. On the basis of the analysis of the kinetics of all pathways through which the reactions proceed, we expect that the competitive power of reaction pathways may vary with experimental conditions for the title reaction.