Kinetic and mechanistic study of Cl reactions with aliphatic thiols. Temperature dependence

Abstract

The mass spectrometric discharge-flow method has been used to investigate the kinetics, mechanism and products of Cl atoms reactions with different aliphatic thiols, CH₃CH₂SH (1), CH₃CH₂CH₂SH (2) and (CH₃)₂CHSH (3) over the temperature range 260–333 K and at low total pressure of 1 Torr. The reactions have been studied under pseudo-first order kinetic conditions in excess of organic compounds over Cl atoms. Arrhenius expressions which describe our results are (units in 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹): k(1) = (3.1 ± 0.7)exp[(−136 ± 70)/T], k(2) = (5.4 ± 2.1)exp[(−227 ± 131)/T] and k(3) = (4.1 ± 1.0)exp[(−125 ± 21)/T]. The mechanisms of the reactions are discussed. The results obtained are related to previous studies of aliphatic thiols with other tropospheric agents and the atmospheric implications are also discussed in relation to the homogeneous sinks of these organic compounds.