Analysis of Chamber-Derived Incremental Reactivity Estimates for N-Butyl Acetate and 2-Butoxy Ethanol

Incremental reactivity estimates for many high molecular weight organic compounds used in consumer products are viewed as uncertain because of limited data on their reaction mechanisms and products. This study performs a systematic uncertainty analysis of the calculated incremental reactivities of two such compounds: n-butyl acetate and 2-butoxy ethanol. 2-butoxy ethanol is a relatively well-studied compound for which incremental reactivity experiments have been performed and product data are available for most reaction pathways. In contrast, there are incremental reactivity experiments but essentially no product data for n-butyl acetate. The uncertainty analysis accounts for uncertainties in the environmental chamber experiments used to estimate key parameters of the 2-butoxy ethanol and n-butyl acetate mechanisms, as well as in the parameters of the base SAPRC-97 chemical mechanism used to calculate their incremental reactivities. Uncertainties in the 2-butoxy ethanol reactivity estimates are lower than those estimated previously for many other volatile organic compounds (VOCs). In contrast, the uncertainties in the n-butyl acetate reactivity estimates are at the upper end of the range of uncertainties estimated for other VOCs. The chamber-derived parameters of the n-butyl acetate and 2-butoxy ethanol mechanisms contribute at most about 7% of the uncertainty in their incremental reactivity estimates.