Computational Study of the Reaction Mechanism and Kinetics of CH₃CHC(CH₃)COOCH₃ Ozonolysis

The reaction mechanism for the ozonolysis of trans-CH₃CHC(CH₃)COOCH₃ as well as the isomerization reaction of CH₃CHOO and CH₃OC(O)C(CH₃)OO) without and with a water molecule were investigated at the G3B3 level. The profile of the potential energy surface (PES) was constructed. Ozone adds to trans-CH₃CHC(CH₃)COOCH₃ via a cyclic transition state to produce a highly unstable primary ozonide that can decompose readily to form P1(CH₃CHOO + CH₃OC(O)C(CH₃)O) and P₂(CH₃CHO + CH₃OC(O)C(CH₃)OO) because the bond breaks in different positions. The total rate constants over the temperature range of 200-1200 K are obtained using the conventional transition state theory with Wigner tunneling correction. The calculated rate constant is 7.55×10^-18 cm³·molecule^-1·s^-1 at 294 K, in good agreement with previous experimental data for similar reactions. The isomerization reaction of CH₃CHOO and CH₃OC (O)C(CH₃)OO) with a water molecule can occur via α-addition process and β-hydrogen transfer mechanism. The former is more favorable than the latter. Compared with the naked isomerization reactions of CH₃CHOO and CH₃OC(O)C(CH₃)OO), the presence of water molecules makes isomerization reactions much easier.