2-AMINO-5-(2-CHLOROPHENYL)-1,3,4-THIADIAZOLE

79-19-6

118-91-2

828-81-9

5.1.1 Synthesis of 5-(2-chlorophenyl)-1,3,4-thiadiazol-2-amine (68): 2-chlorobenzoic acid (5.18 g, 25 mmol) and aminothiourea (2.28 g, 25 mmol) were dissolved in POCl3 (7 ml) and stirred vigorously for 0.5 hr at 75 °C. After completion of the reaction, H2O (30 ml) was added and the mixture was heated to reflux for 4 hours. Subsequently, the reaction mixture was adjusted with 50% NaOH solution to pH 8. The precipitate was collected by filtration and the filter cake was purified by recrystallization from ethanol to give the yellow crystalline product 68 in a yield of 3.90 g, 88% yield, melting point 190-192 °C (EtOH). The product was analyzed by ESI-MS, m/z: 212.1 [M + H]+; 1H NMR (CDCl3) δ 7.45-7.50 (m, 4H), 7.60-7.62 (m, 1H), 7.99-8.01 (m, 1H). Compounds 60-81 were synthesized in the same way.