A Density Functional Theory Study on the Reaction Mechanism of α-Phellandrene with NO₃

In this study, we investigated the relative energies of the chemical species involved in the reaction of α-phellandrene with NO₃ under ambient nighttime conditions to understand the reaction pathway and identify the final products using quantum chemical calculations. The expected main oxidation products are nitrosocabonyl compounds. Although the formation of an oxirane compound is plausible, the reaction might proceed further to produce an aromatic compound. To fully understand α-phellandrene oxidation by NO₃, further study of the detailed reaction mechanism of the formation of an aromatic compound detected by the experiment is needed. Oxidations by OH radical and O₃ are major loss processes for tropospheric monoterpenes during the day. NO₃ radical, which is rapidly photolyzed by sunlight, is a dominant trophospheric oxidant at night because they react rapidly with monoterpens. Some volatile organic compounds produced by the reaction with atmospheric constituents are responsible for the formation of secondary organic aerosols that serve as cloud condensation nuclei inducing a cloud climate effect in the troposphere