Symmetrical Imidazolium Chloride Based on (−)-Menthol: Synthesis, Characterization, and Theoretical Model of the Reaction

New
symmetrical imidazolium chloride from a natural chiral pool
of (1R,2S,5R)-(−)-menthol
can be efficiently prepared by two different methods. The first method
involves a specific type of Menschutkin reaction using novel 1-(1R,2S,5R)-(−)-menthoxymethylimidazole
as amine, chloromethyl (1R,2S,5R)-(−)-menthyl ether as quaternization agent, and
hexane as solvent. In the second method, imidazole, chloromethyl (1R,2S,5R)-(−)-menthyl
ether, and DMF are used. To understand this specific type of the reaction,
quantum chemical calculations at the DFT level have been used. The
preparation and characterization of 1,3-bis­[(1R,2S,5R)-(−)-menthoxymethyl]­imidazolium
chloride are reported.