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.
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.[ Citation 34 ]
d Knoevenagel reaction of 4-methoxybenzaldehyde with malononitrile under solvent-free conditions at room temperature without catalyst.[ Citation 11 ].
e Knoevenagel reaction of 4-chlorobenzaldehyde with malononitrile under solvent-free conditions at 65 °C without catalyst.[ Citation 36 ].
a The reactions were carried out using 1 mol% of EDDA as catalyst under solvent-free conditions at room temperature.
b Isolated yield.