Synthesis
The temperature of the reaction system was maintained at 5-10 °C under continuous stirring and phosphorus oxychloride (POCl3, 2.75 mL, 0.03 mol) was slowly added dropwise to N,N-dimethylformamide (DMF, 3.65 mL, 0.05 mol). Subsequently, 3-(N,N-diethylamino)phenol (0.01 mmol) dissolved in DMF (6 mL) was slowly added to the above cooled mixture at the same temperature. The reaction mixture was stirred at a constant temperature at 75 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature and slowly poured into 60 mL of ice water. The reaction mixture was neutralized with sodium carbonate solution and a brown solid precipitated. The solid product was collected by filtration, washed with cold water, dried and recrystallized from ethanol to give the pure 4-(diethylamino)salicylaldehyde in 80% yield with a melting point of 62 °C (literature value: 62 °C).
References
[1] Organic and Biomolecular Chemistry, 2017, vol. 15, # 12, p. 2575 - 2584
[2] Journal of Fluorescence, 2015, vol. 25, # 6, p. 1615 - 1628
[3] Chemical Communications, 2016, vol. 52, # 60, p. 9434 - 9437
[4] Chemistry Letters, 2011, vol. 40, # 3, p. 279 - 281
[5] Patent: US2789125, 1953,
