N,N-Dimethylaniline → 9-Julolidinylcarboxaldehyde

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Reaction Steps

9-JA is synthesized by the formulation julolidine with phosphorus oxychloride in N,N-dimethyl formamide by a procedure similar to that described for the formulation of N,N-dimethylaniline (Organic Synthesis, Coll. Vol. 4, Wiley, New York, 1963, pp 331-333). N,N-Dimethyl formamide (45 mL) is added to a round bottom flask fitted with a magnetic stirrer, pressure equalizing dropping funnel, and a Claisen head whose sidearm was fitted with a drying tube. The flask is flushed with dry nitrogen and then cooled in a dry ice/isopropyl alcohol bath. Phosphorus oxychloride (16 mL, about 26.3 g) is added. After 10 min, 19 g of julolidine is added dropwise with stirring. The reaction mixture is stirred for 15 min after addition of the julolidine is complete, heated on a steam bath for 2 hr, and poured into a slurry of about 400 mL of crushed ice and water. The resulting solution is carefully neutralized by the addition of 150 g of sodium acetate in 250 mL of water. The precipitated aldehyde is collected by filtration, and the filtrate is kept at 0° C. overnight. The additional precipitate thus formed is collected and combined with the first crop. The combined precipitates are treated with activated charcoal (Darco® G-60) and recrystallized from ethanol/water to give 21.2 g (96%) of 9-JA as light yellow needles, mp 81° C.-82° C. [lit. 83° C., J. Org. Chem., 17, 1281 (1952)].

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