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The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 12
Issue 5 (2007) pp 324-326
An Efficient, Base-Catalyzed, Aqueous Knoevenagel Condensation for the Undergraduate Organic Laboratory
John J. Esteb, Bradley Fravel, John Magers, LuAnne McNulty,* Stacy O’Reilly, and Anne M. Wilson
Butler University, 4600 Sunset Avenue, Indianapolis,
IN
46208, lmcnulty@butler.edu
Received Sept 6, 2006. Accepted December 23, 2006.
Published online: 1 October 2007
Abstract. A green, aqueous, base-catalyzed Knoevenagel experiment between substituted aromatic aldehydes and malononitrile is reported for use in a first-year organic chemistry laboratory course. Weak inorganic bases, such as sodium bicarbonate, sodium acetate, and potassium carbonate effectively catalyzed the reaction. In this experiment, malononitrile, an aldehyde, and an appropriate base are stirred at room temperature for 30 minutes in water. The resulting condensation product precipitates from the solution and can be isolated by suction filtration. Typical student yields range from 50 to 100% depending on the base and aldehyde selected. The ability for these reactions to be run in water greatly reduces the amount of organic waste generated by students and provides a much easier workup compared to a typical carbonyl condensation experiment. Simple aldehydes such as benzaldehyde and cinnamaldehyde produced highly irritating substituted malononitriles, but piperonal, furfural, and 2-napthaldehyde were very useful for this reaction.
Key Words: Laboratories and Demonstrations; organic laboratory; Knoevenagel condensation; carbonyl condensation; aqueous
(*) Corresponding author. (E-mail: lmcnulty@butler.edu)
Article in PDF format (58 KB) HTML format
Supporting Materials:
Full copies of the spectra, a student handout, and a reagent list are available in the supplementary information section (411 KB)Issue date: October
1, 2007
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