N-Benzylidene-N-phenethylamine is an aldimine (an imine which is derived from an aldehyde). It's found naturally in cocoa powders.

N-Benzylidene-N-phenethylamine is a natural adduct created from the alkaloid phenylethylamine and the aldehyde benzaldehyde found in cocoa powder.[1]

Chemical Synthesis

In this example benzaldehyde and phenylethylamine condense to form N-benzylidene-N-phenethylamine. No catalyst is needed.

Benzaldehyde (1.6 mL, 16 mmol, 1 eq) is added slowly to a stirring mixture of diethyl ether (4 mL) and phenylethylamine (2 mL, 16 mmol, 1 eq). The reaction is left to stir at room temperature for 4 hours. The reaction mixture is dried over magnesium sulfate, filtered and then concentrated to give a yellow liquid, which crystallizes on standing giving a yield of 2.7 g (81%) N-benzylidene-N-phenethylamine. Reaction was confirmed by H-NMR.[2]

Aldehyde Condensation Reaction in Cocoa

The quantity of N-benzylidene-N-phenethylamine found in dry cocoa powder increases as the dry cocoa powder ages.

N-Benzylidene-N-phenethylamine occurs naturally as a condensation reaction between the alkaloid phenylethylamine and the aldehyde benzaldehyde in dry cocoa powder. This condensation reaction between phenylethylamine and benzaldehyde produces water as a byproduct.[1]

Condensation Reactants Condensation End Products
Phenylethylamine Benzaldehyde Water N-Benzylidene-N-phenethylamine
Phenylethylamine.png Benzaldehyde.png = H2O.png N-Benzylidene-N-phenethylamine.png

Chemical Properties

Synonyms: N-phenylmethyl-N-phenylmethylene amine; N-phenethyl-1-phenylmethanimine
PubChem Compound ID: 576350
Molecular Weight: 209.2863 [g/mol]
Molecular Formula: C15H15N
XLogP3-AA: 3.5
IUPAC Name: 1-phenyl-N-(2-phenylethyl)methanimine
InChI: InChI=1S/C15H15N/c1-3-7-14(8-4-1)11-12-16-13-15-9-5-2-6-10-15/h1-10,13H,11-12H2
Canonical SMILES: C1=CC=C(C=C1)CCN=CC2=CC=CC=C2

See Also

1. Ziegleder G, Stojacic E, Stumpf B.;
Occurrence of beta-phenylethylamine and its derivatives in cocoa and cocoa products; Fraunhofer-Institut für Lebensmitteltechnologie und Verpackung, München, Bundesrepublik Deutschland.; Z Lebensm Unters Forsch. 1992 Sep;195(3):235-8.; PubMed PMID: 1413998
2. Synthesis of N-benzylidene-N-phenethylamine (KAB18-1)
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