Ionic Liquid Solvation versus Catalysis: Computational Insight from a Multisubstituted Imidazole Synthesis in [Et₂NH₂][HSO₄].

ABSTRACT: The mechanisms of a tetrasubstituted imidazole [2-(2,4,5-triphenyl-1 H-imidazol-1-yl)ethan-1-ol] synthesis from benzil, benzaldehyde, ammonium acetate, and ethanolamine in [Et₂NH₂][HSO₄] ionic liquid (IL) are studied computationally. The effects of the presence of the cationic and anionic components of the IL on transition states and intermediate structures, acting as a solvent versus as a catalyst, are determined. In IL-free medium, carbonyl hydroxylation when using a nucleophile (ammonia) proceeds with a Gibbs free energy (ΔG^≠) barrier of 49.4 kcal mol^-1. Cationic and anionic hydrogen-bond solute-solvent interactions with the IL decrease the barrier to 35.8 kcal mol^-1. [Et₂NH₂][HSO₄]

SUBMITTER: Abdullayev Y 

PROVIDER: S-EPMC5062012 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature