Kinetics of the reactions of the IO radical with dimethyl sulfide, methanethiol, ethylene, and propylene

The reactions of IO radicals with CH 3 SCH 3 , CH 3 SH, C 2 H 4 , and C 3 H 6 have been studied using the discharge flow method with direct detection of IO radicals by mass spectrometry. The absolute rate constants obtained at 298 K are the following: IO + CH 3 SCH 3 → products (1): k 1 = (1.5 ± 0.2) × 10 −14 ; IO + CH 3 SH → products (2): k 2 = (6.6 ± 1.3) × 10 −16 ; IO + C 2 H 4 →products (3): k 3 < 2 × 10 −16 ; IO + C 3 H 6 → products (4): k 4 < 2 × 10 −16 (units are cm 3 molecule −1 s −1 ). CH 3 S(O)CH 3 and HOI were found as products of reactions (1) and (2), respectively. The present lower value of k 1 compared to our previous determination is discussed.