alpha-Pinene organic nitrate synthesis, formation, and simulation

alpha-Pinene (C10H16), a hydrocarbon emitted by vegetation, is the dominant monoterpene in the Earth's atmosphere. With estimated annual global carbon emissions of ∼50 Tg yr-1, alpha-pinene emissions are comparable to anthropogenic hydrocarbon emissions - making its atmospheric oxidation products and reaction pathways a significant component of tropospheric chemistry. The major oxidation pathway of alpha-pinene is reaction with the hydroxyl radical (OH) during the daytime. One important product of OH and alpha-pinene reactions is beta-hydroxynitrates (HOC 10H16ONO2), which represent a terminating step in the alpha-pinene reaction pathway. The formation of these hydroxynitrates prevents the production of NO2, a tropospheric ozone precursor, effectively suppressing ozone while sequestering NOx. With organic nitrates from BOVCs estimated to account for 10-20% of tropospheric ozone generation, organic nitrate chemistry is an important source in the accounting of global ozone concentrations. Results from the first-known organic synthesis of alpha-pinene beta-hydroxynitrates are presented in this work. The synthesis standard supported a series of photochemical reaction chamber studies that reacted pure alpha-pinene with OH in a high NOx environment. The results from these experiments were analyzed to identify for the first time individual alpha-pinene hydroxynitrate isomers, calculate formation yields, and determine the relative branching ratios of the precursor peroxy radical RO2 reacting with NO. A chemistry model was also created to simulate the reaction chamber experimental conditions to compare how well the currently accepted reaction mechanism for the production of these alpha-pinene hydroxynitrates matches experimental results. Lastly, a new portable comprehensive GCxGC (or "two-dimensional GC") was deployed to evaluate its usefulness in gas-phase atmospheric chemistry applications.