Bromine (1.2 g, 7.4 mmol) was added slowly and dropwise to a solution of N-(3,5-dichlorophenyl)thiourea (1.0 g, 3.7 mmol) in chloroform (20 mL) at 0 °C. The reaction mixture was stirred at 60 °C for 10 h. The reaction was subsequently cooled to room temperature and the precipitated solid was collected by filtration. The solid was washed with acetone (4 x 5 mL) to remove unreacted bromine and by-products. The washed solid was dissolved in water (45 mL) and stirred at 95 °C for 30 min. Subsequently, the pH of the reaction solution was adjusted to 9 with 0.5 M sodium hydroxide solution. the precipitated solid was again collected by filtration and dried under vacuum to give 5,7-chlorobenzo[d]thiazol-2-amine (0.68 g, 81% yield) as a violet-gray solid.1H-NMR (CDCl3, 400 MHz) data were as follows: δ 7.43 (d, J = 1.6 Hz, 1H), δ 7.15 (d, J = 1.6Hz, 1H), 5.32 (broad peak, 2H).
