The moisture and air stable ionic liquids 1-butyl-3-methylimidazonium tetrafluoroborate [bmim]BF4 and 1-butyl-3-methylimidazonium hexafluorophosphate [bmim]PF6 were used as ‘green' recyclable alternatives to volatile organic solvents (VOCs) for ethylenediammonium diacetate (EDDA) catalyzed Knoevenagel condensation between aldehydes or ketones with active methylene compounds. Both aldehydes and ketones gave satisfactory results. The ionic liquids containing catalyst EDDA were recycled several times with no decreases in yields and reaction rates. In the case of 2-hydroxybenzaldehyde, the reactions led to the formation of 3-substituted coumarins under standard reaction conditions.
- ionic liquid
- Knoevenagel reaction
- active methylene compounds
Su, C., Chen, Z-C., & Zheng, Q. (2003). Organic reactions in ionic liquids: Knoevenagel condensation catalyzed by ethylenediammonium diacetate. Synthesis, 2003(4), 555-559. https://doi.org/10.1055/s-2003-37643