[Synthesis]
Step A: Tetrabutylammonium bromide (950 mg, 3 mmol, 0.05 eq.) and powdered potassium hydroxide (23.1 g, 411 mmol, 7 eq.) were sequentially added to a toluene (60 mL) solution of 2-pyrrolidone (5.00 g, 58.8 mmol) under stirring conditions. Subsequently, a toluene solution of bromododecane (18.5 mL, 76.4 mmol, 1.3 eq.) was added to the mixture. The reaction mixture was heated to 50 °C and stirred at this temperature overnight. The progress of the reaction was monitored by thin layer chromatography (TLC) using a solvent mixture of ethyl acetate and cyclohexane (4:1, v/v) as the unfolding agent and phosphomolybdic acid as the color developer until the complete disappearance of 2-pyrrolidone. After completion of the reaction, the mixture was cooled to room temperature, 60 mL of water was added and stirring was continued for 15 min. The aqueous and organic phases were separated and the aqueous phase was extracted once with diethyl ether (60 mL). The organic phase was combined, dried with anhydrous sodium sulfate, filtered and concentrated. The product was purified by vacuum distillation (146 °C, 0.5 mbar) to afford N-dodecylpyrrolidin-2-one in 80% yield. The structure of the product was characterized by 1H NMR and 13C NMR: 1H NMR (400 MHz, CDCl3) δ (ppm): 0.88 (t, 3H, J = 7.0 Hz, CH3); 1.25-1.31 (m, 18H, CH2); 1.47-1.54 (m, 2H, Alk-CH2-CH2-N); 1.97- 2.05 (m, 2H, CO-CH2-CH2-CH2-N); 2.38 (t, 2H, J = 8.0 Hz, CO-CH2-CH2-CH2-N); 3.26 (t, 2H, J = 7.5 Hz, Alk-CH2-CH2-N); 3.37 (t, 2H, J = 7.0 Hz, CO-CH2-CH2-CH2- N).13C NMR (100 MHz, CDCl3) δ (ppm): 14.3 (CH3); 18.1 (CO-CH2-CH2-CH2-N); 22.9; 27.0 (CH2alk); 27.5 (Alk-CH2-CH2-N); 29.5; 29.7; 29.8; 29.9 (CH2alk); 31.3 (CO-CH2-CH2-CH2-N); 32.1 (CH2alk); 42.7 (Alk-CH2-CH2-N); 47.2 (CO-CH2-CH2-CH2-N); 174.9 (CO). |