Organic aerosol particles have significant impacts on climate, air quality, and visibility. Our ability to forecast ambient loadings is hindered by gaps in our understanding of the factors that influence the chemical evolution of the condensed phase. The organic fraction of aerosol is immensely complex, resulting from the myriad of processes responsible for its formation. Once formed, this material can be altered through radical driven heterogeneous oxidation with OH, NO3, or O3 and condensed-phase nucleophilic reactions.  Hydrolysis reactions of nitrate esters such as alkyl nitrates and hydroxynitrates, common VOC oxidation products, have been identified as possible nucleophilic reactions in aerosol particles. Further, the products from nucleophilic reactions with nitrate, sulfate, and phosphate ions have also been reported. To date, a few bulk aqueous studies have primarily focused on small organonitrates (C&lt;10), however, larger (C10) terpene-derived species have limited water solubility and are expected to reside primarily in the organic phase. Here, we used the carene-derived β-hydroxynitrate (CHN) as a model structure to explore hydrolysis reactions in organic matrices with dissolved water molecules. Using 2D H-NMR along with authentic standards, bulk phase studies were conducted to probe the influence of solvent identity and pH. Further, because aerosol particles contain a diverse mixture of organic and inorganic species, we also present the results of a series of experiments reacting CHN with  common nucleophiles found in aerosol particles. The results from this work add to our understanding of the role that condensed phase processes play in the chemical evolution of organic aerosol processes.

Nucleophilic reactions of carene β-hydroxynitrate in the condensed phase

ACS Spring 2022

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