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A detailed singlet potential energy surface survey on the 1CF2 + 3O2 reaction is carried out in order to clarify the reaction mechanisms of the singlet difluorocarbene (1CF2) with oxygen (3O2) at the B3LYP/6-311++G(d,p) level. To determine the accurate energies of all stationary points, the QCISD/6-311++G(d,p) single-point calculations are done by using the B3LYP/6-311++G(d,p) optimized geometric structures. The title reaction is important in high temperature processes. Four product channels, P1(F2 + CO2), P2(F2O + CO), P3(2F + CO2) and P4(FCO + FO), have been found in the 1CF2 + 3O2 reaction. P1(F2 + CO2) and P3(2F + CO2) have comparable contributions to the title reaction and they are more favorable than the other two thermodynamically and kinetically.

The mechanism of the reaction of the monobromocarbene (1CHBr) with3O2was studied theoretically at the B3LYP/6-311++G(d,p) level on the singlet potential energy surface (PES). All structures of the stationary points (reactants, intermediates, transition states and products) were optimized and their energies were obtained. Three product channels, P1(HCO + BrO), P2(CO2+ HBr) and P3(CO + HOBr), are found. P2(CO2+ HBr) is the most favorable one both kinetically and thermodynamically.

Subscript textIn order to clarify the reaction mechanisms of the singlet monochlorocarbene radical (1 CHCl) with 3O2 on the singlet potential energy surface (PES), a detailed theoretical study was carried out at the B3LYP/6-311++G(d,p) level. It is found that the first step is the formation of the planar adducts HClCOO via a barrierless association in the 1 CHCl +3 O2 reaction, and then some isomerizations and breakages of bonds takSuperscript texte place, producing P1 (HCO + ClO), P2 (CO2 + HCl) and P3 (CO + HOCl). The product channel of P2 (CO2 + HCl) is the most competitive one both kinetically and thermodynamically. P1 (HCO + ClO) is the least favorable.