Henry’s Law Solubility and Octanol–Water Partition Constants for C1–C5 Alkyl Nitrates of Atmospheric Relevance

Abstract Alkyl nitrates are ubiquitous trace gases in the troposphere. To accurately model their distributions and impacts, parametrizations of their partitioning between gas, aqueous, and organic phases are needed. Here, we report Henry’s law solubility constants(HScp≡H) in n-octanol (Hoct) over the 278–310 K temperature range for methyl, n-propyl, n-butyl, and n-pentyl nitrate (MN, NPN, NBN, and NPeN) and for MN in deionized water (Haq) and synthetic seawater (HSSS), measured by dynamic gas stripping. The Hoct data increase systematically with side-chain length and at 298.15 K range from (7.7 ± 0.7) M atm–1 for MN to (448 ± 20) M atm–1 for NPeN (uncertainties are ±1σ precision). These data were combined with literature Haq values to calculate octanol–water partition constants (KOW), which at 298.15 K range from (3.2 ± 0.3) for MN to (665 ± 31) for NPeN. The Haq and HSSS data for MN are within ∼15% of literature values. Comparison of Hoct and KOW data with estimates by quantitative structure–activity relationship (QSAR) models showed systematic model biases. The data collected in this work will facilitate the training and refinement of future QSAR models to improve their predictive accuracy for larger ANs present in secondary organic aerosol, whose partition constants are challenging to determine experimentally.