1. Potassium carbonate (2.99 g, 21.6 mmol) was placed in a round-bottomed flask and dried under vacuum with a hot air gun.
2. Tetrabutylammonium bromide (0.045 g, 0.14 mmol) and piperazine (1.54 g, 17.9 mmol) dissolved in anhydrous dimethyl sulfoxide (5 mL) were added sequentially.
3. The reaction mixture was stirred at 80 °C, followed by the addition of 4-fluoroacetophenone (2 g, 14.4 mmol) and the reaction was refluxed for 15 h at the same temperature.
4. After completion of the reaction, the mixture was cooled to room temperature, diluted with water and the solid was collected by filtration.
5. The filtrate was acidified with dilute hydrochloric acid and subsequently extracted with ethyl acetate.
6. The aqueous layer was alkalized with sodium hydroxide and extracted with chloroform.
7. The chloroform layers were combined, dried over anhydrous sodium sulfate and concentrated to give the light yellow solid product 4'-piperazineacetophenone (2.23 g, 75.25% yield, melting point 109°C). 8. The product was analyzed by 1H NMR.
8. The product was characterized by 1H NMR (200 MHz, CDCl3): δ 1.91 (s, 1H), 2.52 (s, 3H), 2.98-3.05 (m, 4H), 3.28-3.35 (m, 4H), 6.87 (d, J = 8.8 Hz, 2H), 7.87 (d, J = 8.8 Hz, 2H).
