Pyrolysis and oxidation of ethyl methyl sulfide in a flow reactor

The reactions and kinetics of ethyl methyl sulfide (CH₃CH₂SCH₃, abbreviation CCSC), a simulant for the chemical warfare agent sulfur mustard, were studied at temperatures of 630–740 °C, under highly diluted pyrolysis and oxidation conditions at one atmosphere in a turbulent flow reactor. The loss of the ethyl methyl sulfide and the formation of intermediates and products were correlated with time and temperature. Destruction efficiencies of 50% and 99% were observed for pyrolysis and oxidation, respectively, at 740 °C with a residence time of 0.06 s. For pyrolysis, ethylene, ethane, and methane were detected at significant levels. In addition to these species, carbon monoxide, carbon dioxide, sulfur dioxide, and formaldehyde were detected for oxidation. Conversions of ethyl methyl sulfide were observed to be significantly slower than observed previously for diethyl sulfide; explanations for this observation are postulated, based on: (1) lower hydrogen abstraction rates or on (2) lower hydrogen atom production as a result of thermal decomposition pathways. Initial decomposition reactions and production pathways for important species observed in the experiments are discussed on a basis of thermochemistry.