Highly Efficient Hydration of Epoxides under Atmospheric Pressure and Low Water/Epoxide Ratios by a Tunable Azolate Ionic Liquid through Anion–Cation Synergetic Catalysis

Developing an effective and selective catalyst for epoxide hydration under low water/epoxide ratios and atmospheric pressure is still a challenge. Through tuning the anion, azolate ILs with different basicities were used in the hydration of epoxides. The results showed that the basicity has a great effect on conversion and selectivity, where [Emim][Triz] exhibited high conversion and selectivity under 1 bar CO2, leading to the yield of 99%. Furthermore, these ionic liquids could be used four times and retain good catalytic activity. Spectroscopic investigations, isotope labeling experiments, and quantum chemical calculations indicated that high yield was derived from synergetic catalysis by an azolate ionic liquid, which was more favorable than the hydration process catalyzed by bromine and organic bases.