  Imidazolium cations are promising for anion exchange membranes, and
electrochemical applications and gas capture. They can be chemically modified
in many ways including halogenation. Halogenation possibilities of the
imidazole ring constitute a particular interest. This work investigates
fluorination and chlorination reactions of all symmetrically non-equivalent
sites of the imidazolium cation. Halogenation of all carbon atoms is
thermodynamically permitted. Out of these, the most favorable site is the first
methylene group of the alkyl chain. In turn, the least favorable site is carbon
of the imidazole ring. Temperature dependence of enthalpy, entropy, and Gibbs
free energy at 1 bar is discussed. The reported results provide an important
guidance in functionalization of ionic liquids in search of task-specific
compounds.
