2-Amino-6-chlorobenzothiazole

333-20-0

106-47-8

95-24-9

GENERAL METHOD: A solution of 4-chloroaniline (2 mmol) in acetonitrile (15 ml) was added to a solution of potassium thiocyanate (8 mmol) in acetonitrile (15 ml). Subsequently, 0.06 g (30 mol% BF3) of BF3/SiO2 nanoparticles was added to the mixture, which was then placed in an ice salt bath and mechanically stirred for 30 min. Next, a solution of bromine (4 mmol, 0.2 ml) in acetonitrile (3 ml) was slowly added through a dropping funnel, controlling the rate of addition to ensure that the reaction temperature did not exceed 0 °C. After the addition of bromine, the reaction mixture continued to be stirred at room temperature for 4 h, during which the progress of the reaction was monitored by TLC. Upon completion of the reaction, the mixture was poured into water and heated to 70 °C on a steam bath followed by thermal filtration to remove the catalyst. The recovered catalyst was washed with acetone and reused. The filtrate was neutralized with 10% NaOH solution and the resulting precipitate was collected by filtration, dried and recrystallized from ethanol (10 ml) to give the target product 2-amino-6-chlorobenzothiazole. All 2-aminobenzothiazole products were characterized by physical and spectroscopic data including comparison with real samples. Spectral data of selected products: 6-bromo-1,3-benzothiazol-2-amine (2e) is a yellow solid; yield = 93%; melting point = 202-204 °C (literature value mp = 203 °C); FT-IR (KBr) ν/cm1: 3315, 3012, 2835, 1580, 1476, 1261, 920, 742, 512; 1H NMR (400 MHz. CDCl3) δ ppm: 5.44 (s, 2H, NH2), 7.4-7.5 (d, 2H, Ar-H), 7.71 (s, 1H, Ar-H); 13C NMR (100MHz, DMSO-d6) δ ppm: 119, 120.9, 125.15, 126.07, 133.1, 152.15, 167.75.