3-Bromo-4-chloroquinoline

68158-36-1

74575-17-0

The general procedure for the synthesis of 3-bromo-4-chloroquinoline using 3-bromoquinolin-4(1H)-one as starting material was as follows: phosphorochloridic acid (18.43 g, 0.12 mol) was added slowly and dropwise to a stirring suspension of 3-bromo-1H-quinolin-4-one (22.44 g, 0.10 mol) in acetonitrile (100 mL) at room temperature. The reaction mixture was heated to reflux for 7 hours. Upon completion of the reaction, the mixture was cooled to room temperature and slowly poured into crushed ice (400 mL). Subsequently, the pH of the mixture was adjusted with 10% potassium carbonate solution (220 mL) to 9. The resulting precipitate was collected by filtration, washed well with water and dried under vacuum. The final product was obtained as 3-bromo-4-chloroquinoline as a brown solid (22.58 g, 93% yield) with a melting point of 182-188 °C (literature values: 31 °C, 69-69.5 °C). The product was analyzed by 1H NMR (DMSO-d6, 400MHz) showing δ 9.08 (s, 1H), 8.25 (dd, 1H, J = 0.8, 8.4Hz), 8.12 (d, 1H, J = 8.0Hz), 7.95-7.89 (m, 1H), 7.86-7.80 (m, 1H); 13C NMR (DMSO-d6 , 400 MHz) analysis showed δ 151.6, 146.5, 140.2, 130.9, 129.5, 129.2, 126.4, 124.0, 117.7. The elemental analysis results are in accordance with the theoretical values of C9H5BrClN (molecular weight 242.50): C, 44.58; H, 2.08; N, 5.78; measured values: C 44.43; H, 2.09; N, 5.79. LCMS (ESI+) analysis showed m/z 242, 244 [M + H]+.