The reaction of ozone with dimethyl sulfide (DMS) was studied by quantum chemistry methods. The addition–elimination mechanism is dominant with DMSO and ¹O₂ formed, and H-abstraction mechanism is subdominant. The total rate constant is 1.13 × 10⁻²⁰ cm³·molecule⁻¹·s⁻¹ at 298 K and 1 atm, in good agreement with previous experimental data. The overall rate constants are positive temperature dependent in the whole temperature range.

Abstract

The potential energy surface (PES) for the reaction of ozone with dimethyl sulfide (DMS) was calculated at the CCSD(T)/6-311++G(3df,2pd)//M06-2X/6-311++G(d,p) levels of theory. Result shows that on the singlet PES the addition–elimination mechanism is dominant, and H-abstraction mechanism is less competitive. The major channel starts from the addition of ozone and DMS leading to a weak intermediate IM1, which decomposes subsequently to DMSO and ¹O₂ via a barrier around 38.8 kJ/mol. With a barrier of 64.0 kJ/mol, the formation of HO₃ + CH₃SCH₂ via H-abstraction mechanism is subdominant. Besides, DMSO + ¹O₂ can take place further reactions to produce several products. The substitution mechanism was located on the triplet PES, however, with a rather high barrier it is negligible. Furthermore, the rate constants for the two channels leading to DMSO + ¹O₂ and HO₃ + CH₃SCH₂ were calculated from 200 to 1000 K. The total rate constant is 1.13 × 10^-20 cm³·molecule^-1·s^-1 at 298 K and 1 atm, in good agreement with previous experimental data. The overall rate constants are positive temperature dependent in the whole temperature range.