Kinetics and Mechanism of the O Atom Reaction with Dimethyl Sulfoxide

Abstract

The kinetics and mechanism of the reaction O + DMSO f products (1) have been studied by the mass spectrometric discharge-flow method at 298 K and at a total pressure of 1 Torr of helium. The reaction rate coefficient was measured under pseudo-first-order conditions either from the kinetics of O atom consumption in excess of DMSO or from the kinetics of DMSO decay in excess of O atoms: k 1 ) (1.0 ( 0.2) × 10 -11 cm 3 molecule -1 s -1 (uncertainty includes 2σ statistical error and estimated systematic errors). Both CH 3 and SO 2 were detected as the products of reaction 1, and the reaction O + DMSO f 2CH 3 +SO 2 was found to be the main (if not unique) channel of reaction 1 under the experimental conditions of the study. This result indicates that reaction 1 cannot be a suitable laboratory source of the atmospheric relevant CH 3 SO 2 radical, at least at low pressures. In addition, the upper limits, k 3 < 1 × 10 -13 and k 4 < 5 × 10 -15 cm 3 molecule -1 s -1 , were determined for the rate coefficients of the reactions CH 3 + DMSO f products (3) and Br 2 + DMSO f products (4), respectively. The rate constant of the self-combination of CH 3 radicals, CH 3 + CH 3 (+M) f C 2 H 6 (+M) (2), was also determined in the pressure range between 0.5 and 3.0 Torr of He.

Kinetics of BrO + NO → Br + NO2 Reaction

“…gives 2.1 × 10 −11 at 298 K, the value also given in an extensive list of gas‐phase reactions of inorganic halogens reported by Atkinson et al . and in a paper by Riffault et al . Thus the present model yields rate constants that are lower than the reported data by ~30%.…”

Infrared absorption of CH3SO2 observed upon irradiation of a p-H2 matrix containing CH3I and SO2

“…6 CH 3 SO 2 might be formed also in reactions of OH radicals or O atoms with dimethyl sulfoxide (DMSO). 7,8 Further reactions of CH 3 SO 2 with O 2 , NO 2 , and O 3 lead to formation of sulfate; 9, 10 sulfate particles produced from these oxidation reactions might act as cloud condensation nuclei. 11 Several theoretical computations predict the energy, geometry, and vibrational wavenumbers of CH 3 SO 2 and methoxysulfinyl radical (CH 3 OSO).…”

Environmental effects of large igneous province magmatism: a Siberian perspective

“…The recommended 298 K rate constant is the average of values reported from a laser flash photolysis -resonance fluorescence study by Pope et al [1068], and from a discharge flow − mass spectrometry study by Riffault et al [1119]. A rate constant reported by Barnes et al [76] (with no details about how the rate constant was obtained) is somewhat faster than the recommendation, but in agreement to within the recommended uncertainty factor.…”