Direct ab initio MD study on the hydrogen abstraction reaction of triplet state acetone from methanol molecule

Abstract

Solvent re-orientation process of triplet acetone/methanol complex and intermolecular hydrogen atom abstraction reaction on the triplet state energy surface, (CH3)2C=O (T1) + CH3OH → (CH3)2C–OH + CH2OH in gas phase, have been investigated by means of density functional theory (DFT) and direct ab initio molecular dynamics (MD) methods. The static DFT calculation of hydrogen abstraction reaction at the T1 state showed that the transition state is 16.4 and 30.9 kcal/mol lower than the energy levels of S1 and S2 states, respectively, and 9.2 kcal/mol higher than the bottom of T1 state. The product state, (CH3)2C–OH⋯CH2OH, is 8.4 kcal/mol lower in energy than the level of T1 state. The direct ab initio MD calculation showed that the product is rapidly formed within 150 fs and the separated products (CH3)2C–OH + CH2OH were formed. The mechanism of reaction dynamics of the triplet acetone/methanol complex was discussed on the basis of theoretical results.