Synthesis of 5-methyl-2-mercaptobenzothiazole (10): 2-chloro-5-methylaniline (9, 1.00 g, 7.06 mmol) and potassium carbonate (K2CO3, 2.80 g, 28.2 mmol) were suspended in N,N-dimethylformamide (DMF, 20 mL) under protection of nitrogen. Subsequently, carbon disulfide (CS2, 0.50 mL, 8.50 mmol) was added to the suspension. The reaction mixture was heated and reacted at 150 °C for 16 hours. Upon completion of the reaction, it was cooled to room temperature, the reaction mixture was diluted with deionized water (30 mL) and acidified with 1 N hydrochloric acid (HCl) to a pH of about 1. The resulting precipitate was collected by filtration, washed several times with deionized water, and finally dried under vacuum in the presence of phosphorus pentoxide (P2O5) to afford the target product 5-methyl-2-mercaptobenzothiazole (10, 0.35 g, Yield 27%).
