[Synthesis]
According to the method reported by Siddiqui et al [17], p-chloroacetophenone (0.01 mol) and thiourea (1.52 g, 0.02 mol) were used as raw materials and iodine (2.54 g, 0.01 mol) was added for the reaction. The reaction mixture was heated in an oil bath at 100 °C overnight. After completion of the reaction, it was cooled to room temperature and the reaction mixture was washed with diethyl ether (100 mL) to remove unreacted iodine and p-chloroacetophenone. The solid residue was dissolved in cold water (200 mL) and the pH was adjusted to 9-10 with 25% aqueous ammonium hydroxide.The precipitated 2-amino-5-(4-chlorophenyl)thiazole was collected by filtration and purified by recrystallization with hot ethanol. The product 2-amino-5-(4-chlorophenyl)thiazole (1) had a yield of 81% and a melting point of 168-170 °C. FTIR (KBr pressed sheet, cm?1 ): 3439, 3284 (NH?symmetric and asymmetric stretching vibrations), 1633 (C=N stretching vibration).1H NMR (DMSO-d?, 300 MHz, δ): 7.81-7.79 (d, 2H, benzene ring hydrogen), 7.41-7.38 (d, 2H, benzene ring hydrogen), 7.12 (s, 2H, NH?), 7.04 (s, 1H, thiazole ring hydrogen). Elemental analysis (calculated values, C?H?ClN?S, 210.5 g/mol): C, 51.31; H, 3.33; N, 13.30; S, 15.20. measured values: C, 51.55; H, 3.39; N, 13.50; S, 15.33. |