General procedure for the synthesis of 7-chlorobenzo[d]thiazole-2(3H)-thione from 3-chloro-2-fluoroaniline and potassium ethylxanthate: 3-chloro-2-fluoroaniline (>3 g, 1.0 eq.) and potassium ethylxanthate (1.5-1.7 eq.) were added to a round bottom flask. The mixture was dissolved in N,N-dimethylformamide (DMF, 10 v/v), heated to 120-130 °C, and the reaction was carried out until 3-chloro-2-fluoroaniline was completely consumed (monitored by TLC, reaction time 3-14 h). After completion of the reaction, the reaction mixture was cooled to room temperature and filtered. The filtrate was diluted with deionized water (50 v/v) and the pH was adjusted to 1-2 with 2M aqueous hydrochloric acid.The precipitated solid was collected by filtration, washed with deionized water and dried to give 7-chlorobenzo[d]thiazole-2(3H)-thione in pure form.
