Amines React Rapidly with α-Hydroxyalkyl Hydroperoxides at the Air–Liquid Interface to Form Organic Nitrogen

Atmospheric organic nitrogen (ON) compounds influence aerosol chemistry and climate-relevant processes, yet their sources are not fully understood. Here, we demonstrate that terpenoid-derived α-hydroxyalkyl hydroperoxides (α-HHs), important reactive intermediates in atmospheric aerosols, react rapidly with common atmospheric amines such as ethylamine, dimethylamine, and propylamine at the air-liquid interface to form high-molecular-weight ON compounds. Isotope labeling experiments confirm the product structures and reveal the reaction mechanism. Kinetic analysis shows that these heterogeneous reactions can compete with aqueous-phase hydrolysis, with the half-life of α-pinene-derived α-HHs estimated at ∼19 min exposed to 10 ppt ethylamine, suggesting that amine interactions represent a potentially significant source of ON in aerosols and cloud droplets. This pathway provides new mechanistic insight into the formation of nitrogen-containing aerosols and establishes a link between biogenic volatile organic compounds and ON production, with important implications for aerosol composition, reactivity, and atmospheric chemistry.