Insights into the synergistic influence of [Emim][OAc] and AgOAc for the hydration of propargylic alcohols to α-hydroxy ketones in the presence of CO2

Abstract

[Emim][OAc]/AgOAc has been reported to be an efficient catalyst for the hydration of propargylic alcohols without Hg. However, the mechanism is not easy to elucidate because of the complicated catalytic system. The possible catalytic mechanism is first uncovered in this work using density functional theory (DFT). Eleven routes are chosen and different catalytic components are considered. The proton in the imidazole ring of [Emim][OAc] would interact with the AcO⁻ anion to form the N-heterocyclic carbene (NHC). Then, the NHC–Ag complex is formed via interactions between NHC and the Ag⁺ cation. The NHC–Ag complex and AcO⁻ are used as the catalytic components to prompt the reaction, which is the most favorable route. The contribution of each catalytic species is determined using frontier molecular orbital theory. It is expected that this work will provide some useful information for the further development of other efficient catalysts.