Effect of Chlorine Substitution on Sulfide Reactivity with OH Radicals

摘要

Predicting plume migration and evolution of hazardous chemical species (toxic industrial compounds, chemical warfare agents, pesticides, etc.) is challenging because current models cannot accurately predict reaction rate constants with atmospheric oxidants. Predictive models based on structure activity relationships have not been developed to calculate rate constants for phosphorous or halogen containing compounds (elements that are often present in hazardous chemicals). In order to have a comprehensive approach for modeling plume migration and evolution of hazardous chemicals, rate constants need to be accurately predicted so that chemical degradation can be included. We have studied the effects that chlorine substitution has on the reaction between OH radicals and sulfides to determine the effect halogen substitution has on reactivity. The results show appreciable reduction in the rate constant and a dramatic decrease in the activation energy of the chlorine-substituted organics relative to their unmodified analogs. This implies that the chlorine decreases the stability of the intermediate complex that is formed with the sulfur during the reaction. Atmospheric implications are discussed.