Assessing Melting and Solid–Solid Transition\nProperties of Choline Chloride via Molecular Dynamics Simulations

Choline\nchloride (ChCl) is used extensively as a hydrogen bond\ndonor in deep eutectic solvents (DESs). However, determining its melting\nproperties experimentally is challenging due to decomposition upon\nmelting, leading to widely varying literature values. Accurate melting\nproperties are crucial for understanding the solid–liquid phase\nbehavior of ChCl-containing DESs. Here, we employ molecular dynamics\nsimulations to compute the phase transitions of ChCl, testing a variety\nof atomistic force fields. We find that the results are sensitive\nto the choice of force field, but a melting temperature of 627 K and\na melting enthalpy of 7.8 kJ/mol seem most reasonable, in good agreement\nwith some literature values. We suggest these as the likely melting\nproperties of ChCl, though the results are tentative due to limited\nexperimental data for the liquid ChCl phase.