Furfuraldehyde (ACROS)

piperidine (ACROS)

2,3-butanedione (Sigma-Aldrich)

Absolute ethanol (VWR)

In an Erlenmeyer flask fitted with a stopper, are successively placed furfuraldehyde (21.5 mL; 259.5 mmol), ethanol (20 mL), 2,3-butanedione (11,4 mL; 130.4 mmol) and 4 drops of piperidine. The resulting mixture is stirred at room temperature for 7 d protected from light. The resulting orange precipitate is filtered, washed with cold ethanol until washings are clear and dried under vacuum over P₂O₅. Yield: 1.96 g (6.2%).

Furfuraldehyde must be distilled prior to use. The reaction is easy to perform despite long reaction time and limited yield. Compound so obtained was sufficiently pure to be used without purification.

Mp= 160°C

1H NMR (300 MHz, CDCl₃) ppm = 7.61 (2H, d, J= 15.8 Hz), 7.57 (2H, d, J= 1.5 Hz), 7.30 (2H, d, J= 15.8 Hz), 6.80 (2H, d, J= 3.3 Hz), 6.53 (2H, dd, J= 1.5 Hz, J= 3.3 Hz).

Constable, E.C. et al. Dalton Trans., 2009, 6634.

Hernandez Redondo, A. Ph. D. Thesis, Basel University (Switzerland), 2009. Available online at http://edoc.unibas.ch/994/1/Dissertation_Ana_Hernandez.pdf (accessed 27/09/2011).