Rate Constants for the Gas-Phase Reactions of Ozone and Nitrate Radicals with the Sesquiterpenes: Valencene and Farnesol

ABSTRACT Sesquiterpenes are constituents of a variety of essential oils that are used in flavorings, perfumes, personal care, and cleaning products. Two sesquiterpenes that are commonly used as indoor fragrances are valencene and farnesol. Knowing the reaction rate constants of these chemicals with ozone (O3) and nitrate radical ( NO 3•) is an important factor in determining their fate indoors. In this study, the bimolecular rate constants of kO3+ valencene (0.35±0.9)×10−16, kO3+ farnesol (21±5.2)×10−16, k NO 3•+ valencene (7.9±2.0)×10−12, and k NO 3•+ farnesol (44±11)×10−12 cm 3 molecule −1s−1 were measured using the relative rate technique at 297 ± 3 K and 1 atm total pressure. Using the rate constants reported here and measured/modeled indoor concentrations of O3 and NO 3• (20 ppb and 1 ppt, respectively), pseudo–first‐order‐rate lifetimes kO3+ valencene ′(0.06), kO3+ farnesol ′(3.8), k NO 3′+ valencene (0.7), and k NO 3·+ farnesol ′(3.9)h−1 were determined.