Book of abstracts version 5

Reconstructing the Knoevenagel condensation
g the Knoevenagel condensation
Author
Ouassim L’Karkouri
Academy of Technology for Health and Environment
Avans Hogeschool, Breda
Jack van Schijndel
Abstract
Green chemistry is becoming an important factor with chemical processes. The Knoevenagel condensation is a variant of
the aldol condensation, the aldol condelsation is one of the oldest chemical reaction to form a carbon -carbon bond. The
aldol condensation can either be base or acid catalysed. The Knoevenagel condensation is the same reaction as the aldol
condensation but with amines as catalysis[1]. However in the present day the Knoevenagel condensation is documented
in literature with the same mechanism as the aldol condensation[2]. We think that this is partially incorrect, the amines
used in the Knoevenagel condensation act as organocatalyst instead as a base (figure 1). The goal of this research is to
determine the catalytic intermediate and its catalytic activity of ammonium, 2 -aminoethanol and piperidine in the
Knoevenagel condensation of benzaldehyde, 4-nitrobenzaldehyde and 4-methoxybenzaldehyde with diethylmalonate. We
hypothesise that the catalytic intermediate of ammonium and 2 -aminoethanol a schiff’s base is and piperidine a bis
aminal is. The Schiff’s base intermediates were created by letting benzaldehyde react with ammonium and 2-
aminoethanol at 40°C which results in a condensation. the bis aminal intermediate was created by letting benzaldehyde
react with piperidine at normal conditions. These intermediates are analysed with FT-IR, 1 H-NMR and mel The catalytic
activity of these intermediates is determined by letting benzaldehyde react with diethylmalonate with 2,5% m/m %
catalytic intermediate at 80°C and 100°C. the yield is monitored per time unit with RP-HPLC.
Keywords: Aldol condensation, Knoevenagel condensation, catalys t, Schiff’s base, Bis-aminal
Table of content
Figure 1: proposed knoevenagel condensation path with ammonium.
[1] E. Knoevenagel, '"Condensation von Malonsäure mit aromatischen Aldehyden durch Ammoniak und Amine," Berichte
der deutschen chemischen Gesellschaft, vol. 31, no. 3, pp. 2596 -2619.
[2] A.C.O. Hann and A. Lapworth, '"VII.-Optically active esters of small beta]-ketonic and small beta]- aldehydic acids. Part
IV. Condensation of aldehydes with menthyl acetoacetate," J.Chem.Soc., Trans., vol. 85, no. 0, pp. 46-56.
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