24 JOURNAL OF CHEMICAL RESEARCH 2010
reused in subsequent reactions without adding any amino acid
or ionic liquid. The reaction was performed five times, and
no decrease in yield was observed. This demonstrated that L-
arginine/ionic liquid is an efficient and reusable catalyst and
medium for Knoevenagel condensations.
The procedure reported here provides a green and facile
method for synthesis of α,β-unsaturated nitriles and ketones by
Knoevenagel condensation. The primary amino acid L-arginine
was used as a cheap and recyclable catalyst in the ionic liquid
1-ethyl-3-methylimidazolium ethylsulfate. Knoevenagel con-
densations of aromatic, hetero-aromatic and α,β-unsaturated
aldehydes with malononitrile and acetylacetone were effi-
ciently catalysed at room temperature, and moderate to
excellent yields were achieved.
Received 20 October 2009; accepted 10 December 2009
Paper 090830 doi: 10.3184/030823409X12615671424822
Published online: 22 January 2010
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1
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sulfate
Once the product had been extracted as described above, the aqueous
phase was concentrated in vacuo to remove the water, and the residue
was directly reused in subsequent reactions without adding any amino
acid or ionic liquid.
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