Solvation of nitrogen compounds in Titan’s seas, precipitates, and atmosphere

• We calculated the solubilities of a variety of nitrogen-containing compounds in liquid methane.
• We used a variety of equation of state methods combined with free energy calculations using Thermodynamic Integration.
• We found that nitrogen groups are effective at reducing the solubility in methane.

Saturn’s moon Titan, dominated by its low, 90–95 K, surface temperature and methane seas, is shaped by physical and chemical processes unparalleled in any environment on Earth. Titan’s upper atmosphere produces a rain of compounds such as acetonitrile, acrylonitrile, and acetylene, more familiar to chemical processing plants than to nature. The interaction of these compounds with Titan’s seas is, to a large extent, unknown. As an important first step towards understanding these interactions, we investigate the solvation properties of many of these compounds in methane using multiple theoretical approaches, including cubic equations of state, Statistical Associating Fluid Theory, the Conductor like Screening Model for Real Solvents, and all-atom Molecular Dynamics.