(437f) Phase Equilibria and Separations Involved in the Synthesis of the Ionic Liquid 1-Hexyl-3-Methylimidazolium Bromide ([HMIm][Br]) in Acetone

A vast amount of research on ionic liquids appears in the open and patent literature.  For the future industrial applications, large quantities of ionic liquids will be required.  The scale-up of organic processes has been a longstanding mission of chemical engineering.  However as ionic liquids are touted as potentially environmentally-benign solvents, ILs themselves must also be made in a sustainable manner.  Our previous studies have measured the kinetics and initial human/environmental impact of the production of a model ionic liquid, 1-hexyl-3-methylimidazolium bromide ([HMIm][Br]) in a variety of solvents, including compressed CO₂.  The conventional solvent acetone was determined to be a leading convetional solvent both from a reaction engineering standpoint but also an environmental.  Here, the experimental vapor-liquid equilibrium and liquid-liquid equilibrium involved in the synthesis mixtures of [HMIm][Br] from 1-bromohexane and 1-methylimidazole in acetone have been performed.  The experimental data is modeled using both the Peng-Robinson equation of state and excess Gibbs/activity coefficient models.  These models are then used to simulate potential separation methods with particular attention on the energy demands on producing the ionic liquid at a given purity.