Rapid Continuous-Flow Water-Free Synthesis of Ultrapure Ionic Liquids Assisted by Microwaves

A wide range of imidazole, pyridine including insoluble polymers, and tertiary amine derivatives rapidly reacted with orthoformate using various Brønsted acids or ammonium salts to control the anionic parts. The corresponding ionic liquids were formed in excellent yields under microwave-batch conditions within 10 min. A scale-up synthesis was easily achieved using a microwave flow system. Typically, [BMIM][BF4] was produced at a rate of 26.2 g/h under an Ar atmosphere with an E-factor of 0.8. Both batch and flow experiments were also performed in a domestic microwave oven.