Dicationic Imizadolium‐Based Tetrafluoroborate Ionic Liquids: Synthesis and Hydrothermal Stability Study

Abstract

Six novel dicationic imizadolium‐based tetrafluoroborate ionic liquids were synthesized, with four of which contained hydroxyl groups. Their chemical structures were identified by FTIR and 1H NMR, and their onset decomposition temperatures (Tonset) were measured by thermogravimetric analysis (TGA). For investigating the hydrothermal stability, all DILs were mixed with water and heated for 1, 5, and 9 hours to 240 °C in an airtight kettle.The results show that DILs with hydroxyls have a higher Tonset but they exhibit evident changes in chemical structures after heating with water for 9 hours. The conflicts between Tonset and long‐term stability tests is ascribed to the reason that water forms new hydrogen bonds with hydroxyls and therefore weakens the intramolecular interaction between the cation and anion.