A theoretical study on the reaction mechanism of O2 with C4H9• radical.

Ab initio calculations have been performed using the complete basis set model (CBS-QB3) to study the reaction mechanism of butane radical (C(4)H(9)•) with oxygen (O(2)). On the calculated potential energy surface, the addition of O(2) to C(4)H(9)• forms three intermediates barrierlessly, which can undergo subsequent isomerization or decomposition reaction leading to various products: HOO• + C(4)H(8), C(2)H(5)• + CH(2)CHOOH, OH• + C(3)H(7)CHO, OH• + cycle-C(4)H(8)O, CH(3)• + CH(3)CHCHOOH, CH(2)OOH• + C(3)H(6). Five pathways are supposed in this study. After taking into account the reaction barrier and enthalpy, the most possible reaction pathway is C(4)H(9)• + O(2) → IM1 → TS5 → IM3 → TS6 → IM4 → TS7 → OH• + cycle-C(4)H(8)O.