Efficient Knoevenagel Condensation Catalyzed by 2-Hydroxyethylammonium Acetate Under Solvent-Free Conditions at Room Temperature

Abstract

An efficient method for Knoevenagel condensation of aromatic aldehydes with malononitrile or ethyl cyanoacetate has been developed using the inexpensive and environmentally friendly ionic liquid 2-hydroxyethylammonium acetate as catalyst. The reactions were carried out under solvent-free conditions at room temperature in short periods with simple workup procedure and good to excellent yields.

Keywords:

• Aromatic aldehydes
• ionic liquid
• Knoevenagel condensation
• methylene compounds

Notes

^a Unless otherwise indicated, the reaction was carried out using 2-hydroxyethylammonium acetate (3 mmol), aldehyde (15 mmol), and active methylene compound (15 mmol). All the products are known compounds and were identified by comparison of their melting points and spectral data with those reported.

^b The mixture was stirred at room temperature. After the mixture solidified, the workup was performed.

^c Isolated yield.

^d The amount of 2-hydroxyethylammonium acetate is 0.75 mmol.

^e The amount of 2-hydroxyethylammonium acetate is 1.5 mmol.

^f The amount of 2-hydroxyethylammonium acetate is 4.5 mmol.

^g The second run.

^h The third run.

ⁱ The fourth run.