Tropospheric degradation of propanethiol initiated by Cl radicals: Kinetics, mechanism and computational studies

Abstract

The rate coefficient for the reaction of Cl radicals with n-propanethiol has been determined at 298 K and atmospheric pressure to be: (2.37 ± 0.66) × 10−10 cm3 molecule−1 s−1. Dipropyl disulfide, sulfur dioxide, and propionaldehyde, were observed as main reaction products. The yield of formation of dipropyl disulfide was quantified. Potential energy surfaces and thermodynamic data at 298 K were calculated for the gauche and trans conformers of n-propanethiol using the CBS-QB3, M06-D3/cc-pVTZ and M06-2X/cc-pVTZ levels of theory. We concluded that the formation of the prereactive complex in which chlorine is ‘bound’ to the sulfur atom is the decisive step in the reaction paths.