Simple, Efficient, and Green Procedure for the Knoevenagel Condensation Catalyzed by Ethylenediammonium Diacetate Under Solvent-Free Conditions

Abstract

A simple, efficient, and green procedure for Knoevenagel condensation of aromatic aldehydes with malononitrile and ethyl cyanoacetate catalyzed by ethylenediammonium diacetate under solvent-free conditions at room temperature is reported. This method gives remarkable advantages such as a simple procedure, mild conditions, fast (1–45 min) reactions, and excellent yields. Additionally, the catalyst can be reused for at least five runs without significant decrease of the yields.

Keywords:

• Ethylenediammonium diacetate
• Knoevenagel condensation
• solvent-free conditions

ACKNOWLEDGMENT

Financial support of this work by the Natural Science Foundation of South-Central University for Nationalities is gratefully acknowledged.

Notes

^a The reactions were carried out under solvent-free conditions at room temperature.

^b Isolated yield.

^a Unless otherwise indicated, the reactions of ethyl cyanoacetate with aromatic aldehydes were carried out using 20 mol% of EDDA as catalyst under solvent-free conditions at room temperature. The reactions of malononitrile with aromatic aldehydes were carried out using 1 mol% of EDDA as catalyst under solvent-free conditions at room temperature.

^b Isolated yield.

^c 20 mol % of EDDA-catalyzed Knoevenagel condensation using ionic liquid [bmim]BF₄ as solvent.^{[ 34 ]}

^d Knoevenagel reaction of 4-methoxybenzaldehyde with malononitrile under solvent-free conditions at room temperature without catalyst.^{[ 11 ]}.

^e Knoevenagel reaction of 4-chlorobenzaldehyde with malononitrile under solvent-free conditions at 65 °C without catalyst.^{[ 36 ]}.

^a The reactions were carried out using 1 mol% of EDDA as catalyst under solvent-free conditions at room temperature.

^b Isolated yield.