Ionic Liquids: First Direct Determination of their Cohesive Energy

In contrast to the commonly accepted view that ionic liquids are nonvolatile substances, it was recently shown by Earle et al.1 that they can be distilled under reduced pressure. This fact opens new possibilities for gas-phase processes involving ionic liquids, including their purification, high-temperature crystallization, and novel synthetic routes. It also has important theoretical implica-tions: the nature of the gas phase has to be conclusively identified, and vapor pressure and enthalpy of vaporization data ought to be rigorously determined as they are of inestimable value for the proper validation of molecular simulation protocols as well as the anchorage of parameters for equations of state. Recently, Kabo and collaborators2 derived vapor pressures from Knudsen-type experi-ments. Despite the exceptional research efforts of the past decade in the field of low-temperature molten salts, no unequivocally reliable information exists for their cohesive energy (or enthalp