Interfacial vs Bulk Ozonolysis of Nerolidol

Ozone readily reacts with olefins with the formation of more reactive Criegee intermediates (CIs). The transient CIs impact HO _x cycles, and they play a role in new particle formation in the troposphere. Oxidation by O₃ occurs both in the gas-phase, in the liquid phase, and at air-water and air-aerosol interfaces. In light of the importance of O₃ in environmental and engineered chemical transformations, we have investigated the ozonolysis mechanisms of a triolefin C₁₅-alcohol, nerolidol (Nero, a biogenic sesquiterpene), at the air-water interface in the presence of acetonitrile. Surface-sensitive pneumatic ionization mass spectrometric detection of α-hydroxy-hydroperoxides and functionalized carboxylates, generated by the hydration and isomerization of CIs, respectively, enables us to evaluate the relative reactivity of each C=C toward O₃. In addition, we compare bulk-phase ozonolysis chemistry to similar reactions taking place at the air-water interface. Our experimental results show that O₃ reacts primarily with the (CH₃)₂C=CH- and -(CH₃)C=CH- moieties (>∼98%), while the O₃ attack on the terminal -HC=CH₂ site (<∼2%) is a minor pathway during both interfacial and bulk ozonolysis. The presence of functionalized-carboxylates on interfaces but not in bulk-phase reactions with O₃ indicates that the isomerization of the CIs is not hindered at the air-water interface due to the lower availability of water .